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Title: The Descent of Man and Selection in Relation to Sex, Vol. I
Author: Darwin, Charles, 1809-1882
Language: English
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[_The right of Translation is reserved._]


    Edition (_Tenth Thousand_), with Additions and Corrections.
    1869. MURRAY.

    With Illustrations. 1868. MURRAY.

    numerous Woodcuts. MURRAY.

    voyage of H.M.S. ‘Beagle,’ under the command of Captain FITZROY, R.N.
    _Eleventh Thousand_. MURRAY.




  A MONOGRAPH OF THE CIRRIPEDIA. With numerous Illustrations. 2 vols.
    8vo. HARDWICKE.

    & NORGATE.



  INTRODUCTION                                                  Page 1-5





  Nature of the evidence bearing on the origin of man—Homologous
  structures in man and the lower animals—Miscellaneous points
  of correspondence—Development—Rudimentary structures,
  muscles, sense-organs, hair, bones, reproductive organs,
  &c.—The bearing of these three great classes of facts on the
  origin of man                                                     9-33



  The difference in mental power between the highest ape and the
  lowest savage, immense—Certain instincts in common—The
  Reason—Progressive improvement—Tools and weapons used by
  animals—Language—Self-consciousness—Sense of beauty—Belief
  in God, spiritual agencies, superstitions                        34-69



  The moral sense—Fundamental proposition—The qualities of
  social animals—Origin of sociability—Struggle between opposed
  instincts—Man and social animal—The more enduring social
  instincts conquer other less persistent instincts—The social
  virtues alone regarded by savages—The self-regarding virtues
  acquired at a later stage of development—The importance of the
  judgment of the members of the same community on
  conduct—Transmission of moral tendencies—Summary                70-106



  Variability of body and mind in man—Inheritance—Causes of
  variability—Laws of variation the same in man as in the lower
  animals—Direct action of the conditions of life—Effects of
  the increased use and disuse of parts—Arrested
  development—Reversion—Correlated variation—Rate of
  increase—Checks to increase—Natural selection—Man the most
  dominant animal in the world—Importance of his corporeal
  structure—The causes which have led to his becoming
  erect—Consequent changes of structure—Decrease in size of the
  canine teeth—Increased size and altered shape of the
  skull—Nakedness—Absence of a tail—Defenceless condition of
  man                                                            107-157



  The advancement of the intellectual powers through natural
  selection—Importance of imitation—Social and moral
  faculties—Their development within the limits of the same
  tribe—Natural selection as affecting civilised
  nations—Evidence that civilised nations were once barbarous    158-184



  Position of man in the animal series—The natural system
  genealogical—Adaptive characters of slight value—Various
  small points of resemblance between man and the
  Quadrumana—Rank of man in the natural system—Birthplace and
  antiquity of man—Absence of fossil connecting-links—Lower
  stages in the genealogy of man, as inferred, firstly from his
  affinities and secondly from his structure—Early androgynous
  condition of the Vertebrata—Conclusion                         185-213



  The nature and value of specific characters—Application to the
  races of man—Arguments in favour of, and opposed to, ranking
  the so-called races of man as distinct species—Sub-species—
  Monogenists and polygenists—Convergence of character—Numerous
  points of resemblance in body and mind   between the most
  distinct races of man—The state of man when he first spread
  over the earth—Each race not descended from a single
  pair—The extinction of races—The formation of races—
  The effects of crossing—Slight influence of the direct
  action of the conditions of life—Slight or no influence of
  natural selection—Sexual selection.                            214-250




  Secondary sexual characters—Sexual selection—Manner of
  action—Excess of males—Polygamy—The male alone generally
  modified through sexual selection—Eagerness of the
  male—Variability of the male—Choice exerted by the
  female—Sexual compared with natural selection—Inheritance at
  corresponding periods of life, at corresponding seasons of the
  year, and as limited by sex—Relations between the several
  forms of inheritance—Causes why one sex and the young are not
  modified through sexual selection—Supplement on the
  proportional numbers of the two sexes throughout the animal
  kingdom—On the limitation of the numbers of the two sexes
  through natural selection                                      253-320



  These characters absent in the lowest classes—Brilliant
  colours—Mollusca—Annelids—Crustacea, secondary sexual
  characters strongly developed; dimorphism; colour; characters
  not acquired before maturity—Spiders, sexual colours of;
  stridulation by the males—Myriapoda                            321-340



  Diversified structures possessed by the males for seizing the
  females—Differences between the sexes, of which the meaning is
  not understood—Difference in size between the
  sexes—Thysanura—Diptera—Hemiptera—Homoptera, musical powers
  possessed by the males alone—Orthoptera, musical instruments
  of the males, much diversified in structure; pugnacity;
  colours—Neuroptera, sexual differences in colour—Hymenoptera,
  pugnacity and colours—Coleoptera, colours; furnished with
  great horns, apparently as an ornament; battles; stridulating
  organs generally common to both sexes                          341-385



  Courtship of butterflies—Battles—Ticking noise—Colours
  common to both sexes, or more brilliant in the
  males—Examples—Not due to the direct action of the conditions
  of life—Colours adapted for protection—Colours of
  moths—Display—Perceptive powers of the
  Lepidoptera—Variability—Causes of the difference in colour
  between the males and females—Mimickry, female butterflies
  more brilliantly coloured than the males—Bright colours of
  caterpillars—Summary and concluding remarks on the secondary
  sexual characters of insects—Birds and insects compared        386-423





The nature of the following work will be best understood by a brief
account of how it came to be written. During many years I collected
notes on the origin or descent of man, without any intention of
publishing on the subject, but rather with the determination not to
publish, as I thought that I should thus only add to the prejudices
against my views. It seemed to me sufficient to indicate, in the first
edition of my ‘Origin of Species,’ that by this work “light would be
thrown on the origin of man and his history;” and this implies that man
must be included with other organic beings in any general conclusion
respecting his manner of appearance on this earth. Now the case wears a
wholly different aspect. When a naturalist like Carl Vogt ventures to
say in his address as President of the National Institution of Geneva
(1869), “personne, en Europe au moins, n’ose plus soutenir la création
indépendante et de toutes pièces, des espèces,” it is manifest that at
least a large number of naturalists must admit that species are the
modified descendants of other species; and this especially holds good
with the younger and rising naturalists. The greater number accept the
agency of natural selection; though some urge, whether with justice the
future must decide, that I have greatly overrated its importance. Of the
older and honoured chiefs in natural science, many unfortunately are
still opposed to evolution in every form.

In consequence of the views now adopted by most naturalists, and which
will ultimately, as in every other case, be followed by other men, I
have been led to put together my notes, so as to see how far the general
conclusions arrived at in my former works were applicable to man. This
seemed all the more desirable as I had never deliberately applied these
views to a species taken singly. When we confine our attention to any
one form, we are deprived of the weighty arguments derived from the
nature of the affinities which connect together whole groups of
organisms—their geographical distribution in past and present times,
and their geological succession. The homological structure,
embryological development, and rudimentary organs of a species, whether
it be man or any other animal, to which our attention may be directed,
remain to be considered; but these great classes of facts afford, as it
appears to me, ample and conclusive evidence in favour of the principle
of gradual evolution. The strong support derived from the other
arguments should, however, always be kept before the mind.

The sole object of this work is to consider, firstly, whether man, like
every other species, is descended from some pre-existing form; secondly,
the manner of his development; and thirdly, the value of the
differences between the so-called races of man. As I shall confine
myself to these points, it will not be necessary to describe in detail
the differences between the several races—an enormous subject which has
been fully discussed in many valuable works. The high antiquity of man
has recently been demonstrated by the labours of a host of eminent men,
beginning with M. Boucher de Perthes; and this is the indispensable
basis for understanding his origin. I shall, therefore, take this
conclusion for granted, and may refer my readers to the admirable
treatises of Sir Charles Lyell, Sir John Lubbock, and others. Nor shall
I have occasion to do more than to allude to the amount of difference
between man and the anthropomorphous apes; for Prof. Huxley, in the
opinion of most competent judges, has conclusively shewn that in every
single visible character man differs less from the higher apes than
these do from the lower members of the same order of Primates.

This work contains hardly any original facts in regard to man; but as
the conclusions at which I arrived, after drawing up a rough draft,
appeared to me interesting, I thought that they might interest others.
It has often and confidently been asserted, that man’s origin can never
be known: but ignorance more frequently begets confidence than does
knowledge: it is those who know little, and not those who know much, who
so positively assert that this or that problem will never be solved by
science. The conclusion that man is the co-descendant with other species
of some ancient, lower, and extinct form, is not in any degree new.
Lamarck long ago came to this conclusion, which has lately been
maintained by several eminent naturalists and philosophers; for instance
by Wallace, Huxley, Lyell, Vogt, Lubbock, Büchner, Rolle, &c.,[1] and
especially by Häckel. This last naturalist, besides his great work,
‘Generelle Morphologie’ (1866), has recently (1868, with a second edit.
in 1870), published his ‘Natürliche Schöpfungsgeschichte,’ in which he
fully discusses the genealogy of man. If this work had appeared before
my essay had been written, I should probably never have completed it.
Almost all the conclusions at which I have arrived I find confirmed by
this naturalist, whose knowledge on many points is much fuller than
mine. Wherever I have added any fact or view from Prof. Häckel’s
writings, I give his authority in the text, other statements I leave as
they originally stood in my manuscript, occasionally giving in the
foot-notes references to his works, as a confirmation of the more
doubtful or interesting points.

During many years it has seemed to me highly probable that sexual
selection has played an important part in differentiating the races of
man; but in my ‘Origin of Species’ (first edition, p. 199) I contented
myself by merely alluding to this belief. When I came to apply this view
to man, I found it indispensable to treat the whole subject in full
detail.[2] Consequently the second part of the present work, treating of
sexual selection, has extended to an inordinate length, compared with
the first part; but this could not be avoided.

I had intended adding to the present volumes an essay on the expression
of the various emotions by man and the lower animals. My attention was
called to this subject many years ago by Sir Charles Bell’s admirable
work. This illustrious anatomist maintains that man is endowed with
certain muscles solely for the sake of expressing his emotions. As this
view is obviously opposed to the belief that man is descended from some
other and lower form, it was necessary for me to consider it. I likewise
wished to ascertain how far the emotions are expressed in the same
manner by the different races of man. But owing to the length of the
present work, I have thought it better to reserve my essay, which is
partially completed, for separate publication.






  Nature of the evidence bearing on the origin of man—Homologous
  structures in man and the lower animals—Miscellaneous points
  of correspondence—Development—Rudimentary structures,
  muscles, sense-organs, hair, bones, reproductive organs,
  &c.—The bearing of these three great classes of facts on the
  origin of man.

He who wishes to decide whether man is the modified descendant of some
pre-existing form, would probably first enquire whether man varies,
however slightly, in bodily structure and in mental faculties; and if
so, whether the variations are transmitted to his offspring in
accordance with the laws which prevail with the lower animals; such as
that of the transmission of characters to the same age or sex. Again,
are the variations the result, as far as our ignorance permits us to
judge, of the same general causes, and are they governed by the same
general laws, as in the case of other organisms; for instance by
correlation, the inherited effects of use and disuse, &c.? Is man
subject to similar malconformations, the result of arrested development,
of reduplication of parts, &c., and does he display in any of his
anomalies reversion to some former and ancient type of structure? It
might also naturally be enquired whether man, like so many other
animals, has given rise to varieties and sub-races, differing but
slightly from each other, or to races differing so much that they must
be classed as doubtful species? How are such races distributed over the
world; and how, when crossed, do they react on each other, both in the
first and succeeding generations? And so with many other points.

The enquirer would next come to the important point, whether man tends
to increase at so rapid a rate, as to lead to occasional severe
struggles for existence, and consequently to beneficial variations,
whether in body or mind, being preserved, and injurious ones eliminated.
Do the races or species of men, whichever term may be applied, encroach
on and replace each other, so that some finally become extinct? We shall
see that all these questions, as indeed is obvious in respect to most of
them, must be answered in the affirmative, in the same manner as with
the lower animals. But the several considerations just referred to may
be conveniently deferred for a time; and we will first see how far the
bodily structure of man shows traces, more or less plain, of his descent
from some lower form. In the two succeeding chapters the mental powers
of man, in comparison with those of the lower animals, will be

_The Bodily Structure of Man._—It is notorious that man is constructed
on the same general type or model with other mammals. All the bones in
his skeleton can be compared with corresponding bones in a monkey, bat,
or seal. So it is with his muscles, nerves, blood-vessels and internal
viscera. The brain, the most important of all the organs, follows the
same law, as shewn by Huxley and other anatomists. Bischoff,[3] who is a
hostile witness, admits that every chief fissure and fold in the brain
of man has its analogy in that of the orang; but he adds that at no
period of development do their brains perfectly agree; nor could this be
expected, for otherwise their mental powers would have been the same.
Vulpian[4] remarks: “Les différences réelles qui existent entre
l’encéphale de l’homme et celui des singes supérieurs, sont bien
minimes. Il ne faut pas se faire d’illusions à cet égard. L’homme est
bien plus près des singes anthropomorphes par les caractères anatomiques
de son cerveau que ceux-ci ne le sont non-seulement des autres
mammifères, mais mêmes de certains quadrumanes, des guenons et des
macaques.” But it would be superfluous here to give further details on
the correspondence between man and the higher mammals in the structure
of the brain and all other parts of the body.

It may, however, be worth while to specify a few points, not directly or
obviously connected with structure, by which this correspondence or
relationship is well shewn.

Man is liable to receive from the lower animals, and to communicate to
them, certain diseases as hydrophobia, variola, the glanders, &c.; and
this fact proves the close similarity of their tissues and blood, both
in minute structure and composition, far more plainly than does their
comparison under the best microscope, or by the aid of the best chemical
analysis. Monkeys are liable to many of the same non-contagious diseases
as we are; thus Rengger,[5] who carefully observed for a long time the
_Cebus Azaræ_ in its native land, found it liable to catarrh, with the
usual symptoms, and which when often recurrent led to consumption.
These monkeys suffered also from apoplexy, inflammation of the bowels,
and cataract in the eye. The younger ones when shedding their milk-teeth
often died from fever. Medicines produced the same effect on them as on
us. Many kinds of monkeys have a strong taste for tea, coffee, and
spirituous liquors: they will also, as I have myself seen, smoke tobacco
with pleasure. Brehm asserts that the natives of north-eastern Africa
catch the wild baboons by exposing vessels with strong beer, by which
they are made drunk. He has seen some of these animals, which he kept in
confinement, in this state; and he gives a laughable account of their
behaviour and strange grimaces. On the following morning they were very
cross and dismal; they held their aching heads with both hands and wore
a most pitiable expression: when beer or wine was offered them, they
turned away with disgust, but relished the juice of lemons.[6] An
American monkey, an Ateles, after getting drunk on brandy, would never
touch it again, and thus was wiser than many men. These trifling facts
prove how similar the nerves of taste must be in monkeys and man, and
how similarly their whole nervous system is affected.

Man is infested with internal parasites, sometimes causing fatal
effects, and is plagued by external parasites, all of which belong to
the same genera or families with those infesting other mammals. Man is
subject like other mammals, birds, and even insects, to that mysterious
law, which causes certain normal processes, such as gestation, as well
as the maturation and duration of various diseases, to follow lunar
periods.[7] His wounds are repaired by the same process of healing; and
the stumps left after the amputation of his limbs occasionally possess,
especially during an early embryonic period, some power of regeneration,
as in the lowest animals.[8]

The whole process of that most important function, the reproduction of
the species, is strikingly the same in all mammals, from the first act
of courtship by the male[9] to the birth and nurturing of the young.
Monkeys are born in almost as helpless a condition as our own infants;
and in certain genera the young differ fully as much in appearance from
the adults, as do our children from their full-grown parents.[10] It has
been urged by some writers as an important distinction, that with man
the young arrive at maturity at a much later age than with any other
animal; but if we look to the races of mankind which inhabit tropical
countries the difference is not great, for the orang is believed not to
be adult till the age of from ten to fifteen years.[11] Man differs
from woman in size, bodily strength, hairyness, &c., as well as in mind,
in the same manner as do the two sexes of many mammals. It is, in short,
scarcely possible to exaggerate the close correspondence in general
structure, in the minute structure of the tissues, in chemical
composition and in constitution, between man and the higher animals,
especially the anthropomorphous apes.

_Embryonic Development._—Man is developed from an ovule, about the
125th of an inch in diameter, which differs in no respect from the
ovules of other animals. The embryo itself at a very early period can
hardly be distinguished from that of other members of the vertebrate
kingdom. At this period the arteries run in arch-like branches, as if to
carry the blood to branchiæ which are not present in the higher
vertebrata, though the slits on the sides of the neck still remain (_f_,
_g_, fig. 1), marking their former position. At a somewhat later period,
when the extremities are developed, “the feet of lizards and mammals,”
as the illustrious Von Baer remarks, “the wings and feet of birds, no
less than the hands and feet of man, all arise from the same fundamental
form.” It is, says Prof. Huxley,[12] “quite in the later stages of
development that the young human being presents marked differences from
the young ape, while the latter departs as much from the dog in its
developments, as the man does. Startling as this last assertion may
appear to be, it is demonstrably true.”

As some of my readers may never have seen a drawing of an embryo, I have
given one of man and another of a dog, at about the same early stage of
development, carefully copied from two works of undoubted accuracy.[13]

[Illustration: Fig. 1. Upper figure human embryo, from Ecker. Lower
figure that of a dog, from Bischoff.

  _a._ Fore-brain, cerebral hemispheres, &c.
  _b._ Mid-brain, corpora quadrigemina.
  _c._ Hind-brain, cerebellum, medulla oblongata.
  _d._ Eye.
  _e._ Ear.
  _f._ First visceral arch.
  _g._ Second visceral arch.
   H. Vertebral columns and muscles in process of development.
  _i._ Anterior ┐
                │ extremities.
   K. Posterior ┘
   L. Tail or os coccyx.]

After the foregoing statements made by such high authorities, it would
be superfluous on my part to give a number of borrowed details, shewing
that the embryo of man closely resembles that of other mammals. It may,
however, be added that the human embryo likewise resembles in various
points of structure certain low forms when adult. For instance, the
heart at first exists as a simple pulsating vessel; the excreta are
voided through a cloacal passage; and the os coccyx projects like a true
tail, “extending considerably beyond the rudimentary legs.”[14] In the
embryos of all air-breathing vertebrates, certain glands called the
corpora Wolffiana, correspond with and act like the kidneys of mature
fishes.[15] Even at a later embryonic period, some striking resemblances
between man and the lower animals may be observed. Bischoff says that
the convolutions of the brain in a human fœtus at the end of the
seventh month reach about the same stage of development as in a baboon
when adult.[16] The great toe, as Prof. Owen remarks,[17] “which forms
the fulcrum when standing or walking, is perhaps the most
characteristic peculiarity in the human structure;” but in an embryo,
about an inch in length, Prof. Wyman[18] found “that the great toe was
shorter than the others, and, instead of being parallel to them,
projected at an angle from the side of the foot, thus corresponding with
the permanent condition of this part in the quadrumana.” I will conclude
with a quotation from Huxley,[19] who after asking, does man originate
in a different way from a dog, bird, frog or fish? says, “the reply is
not doubtful for a moment; without question, the mode of origin and the
early stages of the development of man are identical with those of the
animals immediately below him in the scale: without a doubt in these
respects, he is far nearer to apes, than the apes are to the dog.”

_Rudiments._—This subject, though not intrinsically more important than
the two last, will for several reasons be here treated with more
fullness.[20] Not one of the higher animals can be named which does not
bear some part in a rudimentary condition; and man forms no exception to
the rule. Rudimentary organs must be distinguished from those that are
nascent; though in some cases the distinction is not easy. The former
are either absolutely useless, such as the mammæ of male quadrupeds, or
the incisor teeth of ruminants which never cut through the gums; or they
are of such slight service to their present possessors, that we cannot
suppose that they were developed under the conditions which now exist.
Organs in this latter state are not strictly rudimentary, but they are
tending in this direction. Nascent organs, on the other hand, though not
fully developed, are of high service to their possessors, and are
capable of further development. Rudimentary organs are eminently
variable; and this is partly intelligible, as they are useless or nearly
useless, and consequently are no longer subjected to natural selection.
They often become wholly suppressed. When this occurs, they are
nevertheless liable to occasional reappearance through reversion; and
this is a circumstance well worthy of attention.

Disuse at that period of life, when an organ is chiefly used, and this
is generally during maturity, together with inheritance at a
corresponding period of life, seem to have been the chief agents in
causing organs to become rudimentary. The term “disuse” does not relate
merely to the lessened action of muscles, but includes a diminished flow
of blood to a part or organ, from being subjected to fewer alternations
of pressure, or from becoming in any way less habitually active.
Rudiments, however, may occur in one sex of parts normally present in
the other sex; and such rudiments, as we shall hereafter see, have often
originated in a distinct manner. In some cases organs have been reduced
by means of natural selection, from having become injurious to the
species under changed habits of life. The process of reduction is
probably often aided through the two principles of compensation and
economy of growth; but the later stages of reduction, after disuse has
done all that can fairly be attributed to it, and when the saving to be
effected by the economy of growth would be very small,[21] are difficult
to understand. The final and complete suppression of a part, already
useless and much reduced in size, in which case neither compensation nor
economy can come into play, is perhaps intelligible by the aid of the
hypothesis of pangenesis, and apparently in no other way. But as the
whole subject of rudimentary organs has been fully discussed and
illustrated in my former works,[22] I need here say no more on this

Rudiments of various muscles have been observed in many parts of the
human body;[23] and not a few muscles, which are regularly present in
some of the lower animals can occasionally be detected in man in a
greatly reduced condition. Every one must have noticed the power which
many animals, especially horses, possess of moving or twitching their
skin; and this is effected by the panniculus carnosus. Remnants of this
muscle in an efficient state are found in various parts of our bodies;
for instance, on the forehead, by which the eyebrows are raised. The
_platysma myoides_, which is well developed on the neck, belongs to this
system, but cannot be voluntarily brought into action. Prof. Turner, of
Edinburgh, has occasionally detected, as he informs me, muscular
fasciculi in five different situations, namely in the axillæ, near the
scapulæ, &c., all of which must be referred to the system of the
panniculus. He has also shewn[24] that the _musculus sternalis_ or
_sternalis brutorum_, which is not an extension of the _rectus
abdominalis_, but is closely allied to the panniculus, occurred in the
proportion of about 3 per cent. in upwards of 600 bodies: he adds, that
this muscle affords “an excellent illustration of the statement that
occasional and rudimentary structures are especially liable to variation
in arrangement.”

Some few persons have the power of contracting the superficial muscles
on their scalps; and these muscles are in a variable and partially
rudimentary condition. M. A. de Candolle has communicated to me a
curious instance of the long-continued persistence or inheritance of
this power, as well as of its unusual development. He knows a family, in
which one member, the present head of a family, could, when a youth,
pitch several heavy books from his head by the movement of the scalp
alone; and he won wagers by performing this feat. His father, uncle,
grandfather, and all his three children possess the same power to the
same unusual degree. This family became divided eight generations ago
into two branches; so that the head of the above-mentioned branch is
cousin in the seventh degree to the head of the other branch. This
distant cousin resides in another part of France, and on being asked
whether he possessed the same faculty, immediately exhibited his power.
This case offers a good illustration how persistently an absolutely
useless faculty may be transmitted.

The extrinsic muscles which serve to move the whole external ear, and
the intrinsic muscles which move the different parts, all of which
belong to the system of the panniculus, are in a rudimentary condition
in man; they are also variable in development, or at least in function.
I have seen one man who could draw his ears forwards, and another who
could draw them backwards;[25] and from what one of these persons told
me, it is probable that most of us by often touching our ears and thus
directing our attention towards them, could by repeated trials recover
some power of movement. The faculty of erecting the ears and of
directing them to different points of the compass, is no doubt of the
highest service to many animals, as they thus perceive the point of
danger; but I have never heard of a man who possessed the least power of
erecting his ears,—the one movement which might be of use to him. The
whole external shell of the ear may be considered a rudiment, together
with the various folds and prominences (helix and anti-helix, tragus and
anti-tragus, &c.) which in the lower animals strengthen and support the
ear when erect, without adding much to its weight. Some authors,
however, suppose that the cartilage of the shell serves to transmit
vibrations to the acoustic nerve; but Mr. Toynbee,[26] after collecting
all the known evidence on this head, concludes that the external shell
is of no distinct use. The ears of the chimpanzee and orang are
curiously like those of man, and I am assured by the keepers in the
Zoological Gardens that these animals never move or erect them; so that
they are in an equally rudimentary condition, as far as function is
concerned, as in man. Why these animals, as well as the progenitors of
man, should have lost the power of erecting their ears we cannot say. It
may be, though I am not quite satisfied with this view, that owing to
their arboreal habits and great strength they were but little exposed to
danger, and so during a lengthened period moved their ears but little,
and thus gradually lost the power of moving them. This would be a
parallel case with that of those large and heavy birds, which from
inhabiting oceanic islands have not been exposed to the attacks of
beasts of prey, and have consequently lost the power of using their
wings for flight.

[Illustration: Fig. 2. Human Ear, modelled and drawn by Mr. Woolner.

_a._ The projecting point.]

The celebrated sculptor, Mr. Woolner, informs me of one little
peculiarity in the external ear, which he has often observed both in men
and women, and of which he perceived the full signification. His
attention was first called to the subject whilst at work on his figure
of Puck, to which he had given pointed ears. He was thus led to examine
the ears of various monkeys, and subsequently more carefully those of
man. The peculiarity consists in a little blunt point, projecting from
the inwardly folded margin, or helix. Mr. Woolner made an exact model of
one such case, and has sent me the accompanying drawing. (Fig. 2.) These
points not only project inwards, but often a little outwards, so that
they are visible when the head is viewed from directly in front or
behind. They are variable in size and somewhat in position, standing
either a little higher or lower; and they sometimes occur on one ear and
not on the other. Now the meaning of these projections is not, I think,
doubtful; but it may be thought that they offer too trifling a character
to be worth notice. This thought, however, is as false as it is natural.
Every character, however slight, must be the result of some definite
cause; and if it occurs in many individuals deserves consideration. The
helix obviously consists of the extreme margin of the ear folded
inwards; and this folding appears to be in some manner connected with
the whole external ear being permanently pressed backwards. In many
monkeys, which do not stand high in the order, as baboons and some
species of macacus,[27] the upper portion of the ear is slightly
pointed, and the margin is not at all folded inwards; but if the margin
were to be thus folded, a slight point would necessarily project inwards
and probably a little outwards. This could actually be observed in a
specimen of the _Ateles beelzebuth_ in the Zoological Gardens; and we
may safely conclude that it is a similar structure—a vestige of
formerly pointed ears—which occasionally reappears in man.

The nictitating membrane, or third eyelid, with its accessory muscles
and other structures, is especially well developed in birds, and is of
much functional importance to them, as it can be rapidly drawn across
the whole eye-ball. It is found in some reptiles and amphibians, and in
certain fishes, as in sharks. It is fairly well developed in the two
lower divisions of the mammalian series, namely, in the monotremata and
marsupials, and in some few of the higher mammals, as in the walrus. But
in man, the quadrumana, and most other mammals, it exists, as is
admitted by all anatomists, as a mere rudiment, called the semilunar

The sense of smell is of the highest importance to the greater number of
mammals—to some, as the ruminants, in warning them of danger; to
others, as the carnivora, in finding their prey; to others, as the wild
boar, for both purposes combined. But the sense of smell is of extremely
slight service, if any, even to savages, in whom it is generally more
highly developed than in the civilised races. It does not warn them of
danger, nor guide them to their food; nor does it prevent the Esquimaux
from sleeping in the most fetid atmosphere, nor many savages from eating
half-putrid meat. Those who believe in the principle of gradual
evolution, will not readily admit that this sense in its present state
was originally acquired by man, as he now exists. No doubt he inherits
the power in _an_ enfeebled and so far rudimentary condition, from some
early progenitor, to whom it was highly serviceable and by whom it was
continually used. We can thus perhaps understand how it is, as Dr.
Maudsley has truly remarked,[29] that the sense of smell in man “is
singularly effective in recalling vividly the ideas and images of
forgotten scenes and places;” for we see in those animals, which have
this sense highly developed, such as dogs and horses, that old
recollections of persons and places are strongly associated with their

Man differs conspicuously from all the other Primates in being almost
naked. But a few short straggling hairs are found over the greater part
of the body in the male sex, and fine down on that of the female sex, In
individuals belonging to the same race these hairs are highly variable,
not only in abundance, but likewise in position: thus the shoulders in
some Europeans are quite naked, whilst in others they bear thick tufts
of hair.[30] There can be little doubt that the hairs thus scattered
over the body are the rudiments of the uniform hairy coat of the lower
animals. This view is rendered all the more probable, as it is known
that fine, short, and pale-coloured hairs on the limbs and other parts
of the body occasionally become developed into “thickset, long, and
rather coarse dark hairs,” when abnormally nourished near old-standing
inflamed surfaces.[31]

I am informed by Mr. Paget that persons belonging to the same family
often have a few hairs in their eyebrows much longer than the others; so
that this slight peculiarity seems to be inherited. These hairs
apparently represent the vibrissæ, which are used as organs of touch by
many of the lower animals. In a young chimpanzee I observed that a few
upright, rather long, hairs, projected above the eyes, where the true
eyebrows, if present, would have stood.

The fine wool-like hair, or so-called lanugo, with which the human
fœtus during the sixth month is thickly covered, offers a more
curious case. It is first developed, during the fifth month, on the
eyebrows and face, and especially round the mouth, where it is much
longer than that on the head. A moustache of this kind was observed by
Eschricht[32] on a female fœtus; but this is not so surprising a
circumstance as it may at first appear, for the two sexes generally
resemble each other in all external characters during an early period of
growth. The direction and arrangement of the hairs on all parts of the
fœtal body are the same as in the adult, but are subject to much
variability. The whole surface, including even the forehead and ears, is
thus thickly clothed; but it is a significant fact that the palms of the
hands and the soles of the feet are quite naked, like the inferior
surfaces of all four extremities in most of the lower animals. As this
can hardly be an accidental coincidence, we must consider the woolly
covering of the fœtus to be the rudimental representative of the
first permanent coat of hair in those mammals which are born hairy. This
representation is much more complete, in accordance with the usual law
of embryological development, than that afforded by the straggling hairs
on the body of the adult.

It appears as if the posterior molar or wisdom-teeth were tending to
become rudimentary in the more civilised races of man. These teeth are
rather smaller than the other molars, as is likewise the case with the
corresponding teeth in the chimpanzee and orang; and they have only two
separate fangs. They do not cut through the gums till about the
seventeenth year, and I am assured by dentists that they are much more
liable to decay, and are earlier lost, than the other teeth. It is also
remarkable that they are much more liable to vary both in structure and
in the period of their development than the other teeth.[33] In the
Melanian races, on the other hand, the wisdom-teeth are usually
furnished with three separate fangs, and are generally sound: they also
differ from the other molars in size less than in the Caucasian
races.[34] Prof. Schaaffhausen accounts for this difference between the
races by “the posterior dental portion of the jaw being always
shortened” in those that are civilised,[35] and this shortening may, I
presume, be safely attributed to civilised men habitually feeding on
soft, cooked food, and thus using their jaws less. I am informed by Mr.
Brace that it is becoming quite a common practice in the United States
to remove some of the molar teeth of children, as the jaw does not grow
large enough for the perfect development of the normal number.

With respect to the alimentary canal I have met with an account of only
a single rudiment, namely the vermiform appendage of the cæcum. The
cæcum is a branch or diverticulum of the intestine, ending in a
cul-de-sac, and it is extremely long in many of the lower
vegetable-feeding mammals. In the marsupial koala it is actually more
than thrice as long as the whole body.[36] It is sometimes produced into
a long gradually-tapering point, and is sometimes constricted in parts.
It appears as if, in consequence of changed diet or habits, the cæcum
had become much shortened in various animals, the vermiform appendage
being left as a rudiment of the shortened part. That this appendage is a
rudiment, we may infer from its small size, and from the evidence which
Prof. Canestrini[37] has collected of its variability in man. It is
occasionally quite absent, or again is largely developed. The passage is
sometimes completely closed for half or two-thirds of its length, with
the terminal part consisting of a flattened solid expansion. In the
orang this appendage is long and convoluted: in man it arises from the
end of the short cæcum, and is commonly from four to five inches in
length, being only about the third of an inch in diameter. Not only is
it useless, but it is sometimes the cause of death, of which fact I have
lately heard two instances: this is due to small hard bodies, such as
seeds, entering the passage and causing inflammation.[38]

In the Quadrumana and some other orders of mammals, especially in the
Carnivora, there is a passage near the lower end of the humerus, called
the supra-condyloid foramen, through which the great nerve of the fore
limb passes, and often the great artery. Now in the humerus of man, as
Dr. Struthers[39] and others have shewn, there is generally a trace of
this passage, and it is sometimes fairly well developed, being formed by
a depending hook-like process of bone, completed by a band of ligament.
When present the great nerve invariably passes through it, and this
clearly indicates that it is the homologue and rudiment of the
supra-condyloid foramen of the lower animals. Prof. Turner estimates, as
he informs me, that it occurs in about one per cent. of recent
skeletons; but during ancient times it appears to have been much more
common. Mr. Busk[40] has collected the following evidence on this head:
Prof. Broca “noticed the perforation in four and a half per cent. of the
arm-bones collected in the ‘Cimetière du Sud’ at Paris; and in the
Grotto of Orrony, the contents of which are referred to the Bronze
period, as many as eight humeri out of thirty-two were perforated; but
this extraordinary proportion, he thinks, might be due to the cavern
having been a sort of ‘family vault.’ Again, M. Dupont found 30 per
cent. of perforated bones in the caves of the Valley of the Lesse,
belonging to the Reindeer period; whilst M. Leguay, in a sort of
_dolmen_ at Argenteuil, observed twenty-five per cent. to be perforated;
and M. Pruner-Bey found twenty-six per cent. in the same condition in
bones from Vauréal. Nor should it be left unnoticed that M. Pruner-Bey
states that this condition is common in Guanche skeletons.” The fact
that ancient races, in this and several other cases, more frequently
present structures which resemble those of the lower animals than do the
modern races, is interesting. One chief cause seems to be that ancient
races stand somewhat nearer than modern races in the long line of
descent to their remote animal-like progenitors.

The os coccyx in man, though functionless as a tail, plainly represents
this part in other vertebrate animals. At an early embryonic period it
is free, and, as we have seen, projects beyond the lower extremities. In
certain rare and anomalous cases it has been known, according to Isidore
Geoffroy St.-Hilaire and others,[41] to form a small external rudiment
of a tail. The os coccyx is short, usually including only four vertebræ:
and these are in a rudimental condition, for they consist, with the
exception of the basal one, of the centrum alone.[42] They are furnished
with some small muscles; one of which, as I am informed by Prof. Turner,
has been expressly described by Theile as a rudimentary repetition of
the extensor of the tail, which is so largely developed in many mammals.

The spinal cord in man extends only as far downwards as the last dorsal
or first lumbar vertebra; but a thread-like structure (the _filum
terminale_) runs down the axis of the sacral part of the spinal canal,
and even along the back of the coccygeal bones. The upper part of this
filament, as Prof. Turner informs me, is undoubtedly homologous with the
spinal cord; but the lower part apparently consists merely of the _pia
mater_, or vascular investing membrane. Even in this case the os coccyx
may be said to possess a vestige of so important a structure as the
spinal cord, though no longer enclosed within a bony canal. The
following fact, for which I am also indebted to Prof. Turner, shews how
closely the os coccyx corresponds with the true tail in the lower
animals: Luschka has recently discovered at the extremity of the
coccygeal bones a very peculiar convoluted body, which is continuous
with the middle sacral artery; and this discovery led Krause and Meyer
to examine the tail of a monkey (Macacus) and of a cat, in both of which
they found, though not at the extremity, a similarly convoluted body.

The reproductive system offers various rudimentary structures; but these
differ in one important respect from the foregoing cases. We are not
here concerned with a vestige of a part which does not belong to the
species in an efficient state; but with a part which is always present
and efficient in the one sex, being represented in the other by a mere
rudiment. Nevertheless, the occurrence of such rudiments is as difficult
to explain on the belief of the separate creation of each species, as in
the foregoing cases. Hereafter I shall have to recur to these rudiments,
and shall shew that their presence generally depends merely on
inheritance; namely, on parts acquired by one sex having been partially
transmitted to the other. Here I will only give some instances of such
rudiments. It is well known that in the males of all mammals, including
man, rudimentary mammæ exist. These in several instances have become
well developed, and have yielded a copious supply of milk. Their
essential identity in the two sexes is likewise shewn by their
occasional sympathetic enlargement in both during an attack of the
measles. The _vesicula prostatica_, which has been observed in many
male mammals, is now universally acknowledged to be the homologue of the
female uterus, together with the connected passage. It is impossible to
read Leuckart’s able description of this organ, and his reasoning,
without admitting the justness of his conclusion. This is especially
clear in the case of those mammals in which the true female uterus
bifurcates, for in the males of these the vesicula likewise
bifurcates.[43] Some additional rudimentary structures belonging to the
reproductive system might here have been adduced.[44]

The bearing of the three great classes of facts now given is
unmistakeable. But it would be superfluous here fully to recapitulate
the line of argument given in detail in my ‘Origin of Species.’ The
homological construction of the whole frame in the members of the same
class is intelligible, if we admit their descent from a common
progenitor, together with their subsequent adaptation to diversified
conditions. On any other view the similarity of pattern between the hand
of a man or monkey, the foot of a horse, the flipper of a seal, the wing
of a bat, &c., is utterly inexplicable. It is no scientific explanation
to assert that they have all been formed on the same ideal plan. With
respect to development, we can clearly understand, on the principle of
variations supervening at a rather late embryonic period, and being
inherited at a corresponding period, how it is that the embryos of
wonderfully different forms should still retain, more or less perfectly,
the structure of their common progenitor. No other explanation has ever
been given of the marvellous fact that the embryo of a man, dog, seal,
bat, reptile, &c., can at first hardly be distinguished from each other.
In order to understand the existence of rudimentary organs, we have only
to suppose that a former progenitor possessed the parts in question in a
perfect state, and that under changed habits of life they became greatly
reduced, either from simple disuse, or through the natural selection of
those individuals which were least encumbered with a superfluous part,
aided by the other means previously indicated.

Thus we can understand how it has come to pass that man and all other
vertebrate animals have been constructed on the same general model, why
they pass through the same early stages of development, and why they
retain certain rudiments in common. Consequently we ought frankly to
admit their community of descent: to take any other view, is to admit
that our own structure and that of all the animals around us, is a mere
snare laid to entrap our judgment. This conclusion is greatly
strengthened, if we look to the members of the whole animal series, and
consider the evidence derived from their affinities or classification,
their geographical distribution and geological succession. It is only
our natural prejudice, and that arrogance which made our forefathers
declare that they were descended from demi-gods, which leads us to demur
to this conclusion. But the time will before long come when it will be
thought wonderful, that naturalists, who were well acquainted with the
comparative structure and development of man and other mammals, should
have believed that each was the work of a separate act of creation.



  The difference in mental power between the highest ape and the
  lowest savage, immense—Certain instincts in common—The
  —Reason—Progressive improvement—Tools and weapons used by
  animals—Language—Self-consciousness—Sense of beauty—Belief
  in God, spiritual agencies, superstitions.

We have seen in the last chapter that man bears in his bodily structure
clear traces of his descent from some lower form; but it may be urged
that, as man differs so greatly in his mental power from all other
animals, there must be some error in this conclusion. No doubt the
difference in this respect is enormous, even if we compare the mind of
one of the lowest savages, who has no words to express any number higher
than four, and who uses no abstract terms for the commonest objects or
affections,[45] with that of the most highly organised ape. The
difference would, no doubt, still remain immense, even if one of the
higher apes had been improved or civilised as much as a dog has been in
comparison with its parent-form, the wolf or jackal. The Fuegians rank
amongst the lowest barbarians; but I was continually struck with
surprise how closely the three natives on board H.M.S. “Beagle,” who had
lived some years in England and could talk a little English, resembled
us in disposition and in most of our mental faculties. If no organic
being excepting man had possessed any mental power, or if his powers had
been of a wholly different nature from those of the lower animals, then
we should never have been able to convince ourselves that our high
faculties had been gradually developed. But it can be clearly shewn that
there is no fundamental difference of this kind. We must also admit that
there is a much wider interval in mental power between one of the lowest
fishes, as a lamprey or lancelet, and one of the higher apes, than
between an ape and man; yet this immense interval is filled up by
numberless gradations.

Nor is the difference slight in moral disposition between a barbarian,
such as the man described by the old navigator Byron, who dashed his
child on the rocks for dropping a basket of sea-urchins, and a Howard or
Clarkson; and in intellect, between a savage who does not use any
abstract terms, and a Newton or Shakspeare. Differences of this kind
between the highest men of the highest races and the lowest savages, are
connected by the finest gradations. Therefore it is possible that they
might pass and be developed into each other.

My object in this chapter is solely to shew that there is no fundamental
difference between man and the higher mammals in their mental faculties.
Each division of the subject might have been extended into a separate
essay, but must here be treated briefly. As no classification of the
mental powers has been universally accepted, I shall arrange my remarks
in the order most convenient for my purpose; and will select those facts
which have most struck me, with the hope that they may produce some
effect on the reader.

With respect to animals very low in the scale, I shall have to give some
additional facts under Sexual Selection, shewing that their mental
powers are higher than might have been expected. The variability of the
faculties in the individuals of the same species is an important point
for us, and some few illustrations will here be given. But it would be
superfluous to enter into many details on this head, for I have found on
frequent enquiry, that it is the unanimous opinion of all those who have
long attended to animals of many kinds, including birds, that the
individuals differ greatly in every mental characteristic. In what
manner the mental powers were first developed in the lowest organisms,
is as hopeless an enquiry as how life first originated. These are
problems for the distant future, if they are ever to be solved by man.

As man possesses the same senses with the lower animals, his fundamental
intuitions must be the same. Man has also some few instincts in common,
as that of self-preservation, sexual love, the love of the mother for
her new-born offspring, the power possessed by the latter of sucking,
and so forth. But man, perhaps, has somewhat fewer instincts than those
possessed by the animals which come next to him in the series. The orang
in the Eastern islands, and the chimpanzee in Africa, build platforms on
which they sleep; and, as both species follow the same habit, it might
be argued that this was due to instinct, but we cannot feel sure that it
is not the result of both animals having similar wants and possessing
similar powers of reasoning. These apes, as we may assume, avoid the
many poisonous fruits of the tropics, and man has no such knowledge; but
as our domestic animals, when taken to foreign lands and when first
turned out in the spring, often eat poisonous herbs, which they
afterwards avoid, we cannot feel sure that the apes do not learn from
their own experience or from that of their parents what fruits to
select. It is however certain, as we shall presently see, that apes
have an instinctive dread of serpents, and probably of other dangerous

The fewness and the comparative simplicity of the instincts in the
higher animals are remarkable in contrast with those of the lower
animals. Cuvier maintained that instinct and intelligence stand in an
inverse ratio to each other; and some have thought that the intellectual
faculties of the higher animals have been gradually developed from their
instincts. But Pouchet, in an interesting essay,[46] has shewn that no
such inverse ratio really exists. Those insects which possess the most
wonderful instincts are certainly the most intelligent. In the
vertebrate series, the least intelligent members, namely fishes and
amphibians, do not possess complex instincts; and amongst mammals the
animal most remarkable for its instincts, namely the beaver, is highly
intelligent, as will be admitted by every one who has read Mr. Morgan’s
excellent account of this animal.[47]

Although the first dawnings of intelligence, according to Mr. Herbert
Spencer,[48] have been developed through the multiplication and
co-ordination of reflex actions, and although many of the simpler
instincts graduate into actions of this kind and can hardly be
distinguished from them, as in the case of young animals sucking, yet
the more complex instincts seem to have originated independently of
intelligence. I am, however, far from wishing to deny that instinctive
actions may lose their fixed and untaught character, and be replaced by
others performed by the aid of the free will. On the other hand, some
intelligent actions—as when, birds on oceanic islands first learn to
avoid man—after being performed during many generations, become
converted into instincts and are inherited. They may then be said to be
degraded in character, for they are no longer performed through reason
or from experience. But the greater number of the more complex instincts
appear to have been gained in a wholly different manner, through the
natural selection of variations of simpler instinctive actions. Such
variations appear to arise from the same unknown causes acting on the
cerebral organisation, which induce slight variations or individual
differences in other parts of the body; and these variations, owing to
our ignorance, are often said to arise spontaneously. We can, I think,
come to no other conclusion with respect to the origin of the more
complex instincts, when we reflect on the marvellous instincts of
sterile worker-ants and bees, which leave no offspring to inherit the
effects of experience and of modified habits.

Although a high degree of intelligence is certainly compatible with the
existence of complex instincts, as we see in the insects just named and
in the beaver, it is not improbable that they may to a certain extent
interfere with each other’s development. Little is known about the
functions of the brain, but we can perceive that as the intellectual
powers become highly developed, the various parts of the brain must be
connected by the most intricate channels of intercommunication; and as a
consequence each separate part would perhaps tend to become less well
fitted to answer in a definite and uniform, that is instinctive, manner
to particular sensations or associations.

I have thought this digression worth giving, because we may easily
underrate the mental powers of the higher animals, and especially of
man, when we compare their actions founded on the memory of past events,
on foresight, reason, and imagination, with exactly similar actions
instinctively performed by the lower animals; in this latter case the
capacity of performing such actions having been gained, step by step,
through the variability of the mental organs and natural selection,
without any conscious intelligence on the part of the animal during each
successive generation. No doubt, as Mr. Wallace has argued,[49] much of
the intelligent work done by man is due to imitation and not to reason;
but there is this great difference between his actions and many of those
performed by the lower animals, namely, that man cannot, on his first
trial, make, for instance, a stone hatchet or a canoe, through his power
of imitation. He has to learn his work by practice; a beaver, on the
other hand, can make its dam or canal, and a bird its nest, as well, or
nearly as well, the first time it tries, as when old and experienced.

To return to our immediate subject: the lower animals, like man,
manifestly feel pleasure and pain, happiness and misery. Happiness is
never better exhibited than by young animals, such as puppies, kittens,
lambs, &c., when playing together, like our own children. Even insects
play together, as has been described by that excellent observer, P.
Huber,[50] who saw ants chasing and pretending to bite each other, like
so many puppies.

The fact that the lower animals are excited by the same emotions as
ourselves is so well established, that it will not be necessary to weary
the reader by many details. Terror acts in the same manner on them as on
us, causing the muscles to tremble, the heart to palpitate, the
sphincters to be relaxed, and the hair to stand on end. Suspicion, the
offspring of fear, is eminently characteristic of most wild animals.
Courage and timidity are extremely variable qualities in the
individuals of the same species, as is plainly seen in our dogs. Some
dogs and horses are ill-tempered and easily turn sulky; others are
good-tempered; and these qualities are certainly inherited. Every one
knows how liable animals are to furious rage, and how plainly they show
it. Many anecdotes, probably true, have been published on the
long-delayed and artful revenge of various animals. The accurate Rengger
and Brehm[51] state that the American and African monkeys which they
kept tame, certainly revenged themselves. The love of a dog for his
master is notorious; in the agony of death he has been known to caress
his master, and every one has heard of the dog suffering under
vivisection, who licked the hand of the operator; this man, unless he
had a heart of stone, must have felt remorse to the last hour of his
life. As Whewell[52] has remarked, “who that reads the touching
instances of maternal affection, related so often of the women of all
nations, and of the females of all animals, can doubt that the principle
of action is the same in the two cases?”

We see maternal affection exhibited in the most trifling details; thus
Rengger observed an American monkey (a Cebus) carefully driving away the
flies which plagued her infant; and Duvaucel saw a Hylobates washing the
faces of her young ones in a stream. So intense is the grief of female
monkeys for the loss of their young, that it invariably caused the death
of certain kinds kept under confinement by Brehm in N. Africa.
Orphan-monkeys were always adopted and carefully guarded by the other
monkeys, both males and females. One female baboon had so capacious a
heart that she not only adopted young monkeys of other species, but
stole young dogs and cats, which she continually carried about. Her
kindness, however, did not go so far as to share her food with her
adopted offspring, at which Brehm was surprised, as his monkeys always
divided everything quite fairly with their own young ones. An adopted
kitten scratched the above-mentioned affectionate baboon, who certainly
had a fine intellect, for she was much astonished at being scratched,
and immediately examined the kitten’s feet, and without more ado bit off
the claws. In the Zoological Gardens, I heard from the keeper that an
old baboon (_C. chacma_) had adopted a Rhesus monkey; but when a young
drill and mandrill were placed in the cage, she seemed to perceive that
these monkeys, though distinct species, were her nearer relatives, for
she at once rejected the Rhesus and adopted both of them. The young
Rhesus, as I saw, was greatly discontented at being thus rejected, and
it would, like a naughty child, annoy and attack the young drill and
mandrill whenever it could do so with safety; this conduct exciting
great indignation in the old baboon. Monkeys will also, according to
Brehm, defend their master when attacked by any one, as well as dogs to
whom they are attached, from the attacks of other dogs. But we here
trench on the subject of sympathy, to which I shall recur. Some of
Brehm’s monkeys took much delight in teasing, in various ingenious ways,
a certain old dog whom they disliked, as well as other animals.

Most of the more complex emotions are common to the higher animals and
ourselves. Every one has seen how jealous a dog is of his master’s
affection, if lavished on any other creature; and I have observed the
same fact with monkeys. This shews that animals not only love, but have
the desire to be loved. Animals manifestly feel emulation. They love
approbation or praise; and a dog carrying a basket for his master
exhibits in a high degree self-complacency or pride. There can, I think,
be no doubt that a dog feels shame, as distinct from fear, and something
very like modesty when begging too often for food. A great dog scorns
the snarling of a little dog, and this may be called magnanimity.
Several observers have stated that monkeys certainly dislike being
laughed at; and they sometimes invent imaginary offences. In the
Zoological Gardens I saw a baboon who always got into a furious rage
when his keeper took out a letter or book and read it aloud to him; and
his rage was so violent that, as I witnessed on one occasion, he bit his
own leg till the blood flowed.

We will now turn to the more intellectual emotions and faculties, which
are very important, as forming the basis for the development of the
higher mental powers. Animals manifestly enjoy excitement and suffer
from ennui, as may be seen with dogs, and, according to Rengger, with
monkeys. All animals feel Wonder, and many exhibit Curiosity. They
sometimes suffer from this latter quality, as when the hunter plays
antics and thus attracts them; I have witnessed this with deer, and so
it is with the wary chamois, and with some kinds of wild-ducks. Brehm
gives a curious account of the instinctive dread which his monkeys
exhibited towards snakes; but their curiosity was so great that they
could not desist from occasionally satiating their horror in a most
human fashion, by lifting up the lid of the box in which the snakes were
kept. I was so much surprised at his account, that I took a stuffed and
coiled-up snake into the monkey-house at the Zoological Gardens, and the
excitement thus caused was one of the most curious spectacles which I
ever beheld. Three species of Cercopithecus were the most alarmed; they
dashed about their cages and uttered sharp signal-cries of danger, which
were understood by the other monkeys. A few young monkeys and one old
Anubis baboon alone took no notice of the snake. I then placed the
stuffed specimen on the ground in one of the larger compartments. After
a time all the monkeys collected round it in a large circle, and staring
intently, presented a most ludicrous appearance. They became extremely
nervous; so that when a wooden ball, with which they were familiar as a
plaything, was accidently moved in the straw, under which it was partly
hidden, they all instantly started away. These monkeys behaved very
differently when a dead fish, a mouse, and some other new objects were
placed in their cages; for though at first frightened, they soon
approached, handled and examined them. I then placed a live snake in a
paper bag, with the mouth loosely closed, in one of the larger
compartments. One of the monkeys immediately approached, cautiously
opened the bag a little, peeped in, and instantly dashed away. Then I
witnessed what Brehm has described, for monkey after monkey, with head
raised high and turned on one side, could not resist taking momentary
peeps into the upright bag, at the dreadful object lying quiet at the
bottom. It would almost appear as if monkeys had some notion of
zoological affinities, for those kept by Brehm exhibited a strange,
though mistaken, instinctive dread of innocent lizards and frogs. An
orang, also, has been known to be much alarmed at the first sight of a

The principle of _Imitation_ is strong in man, and especially in man in
a barbarous state. Desor[54] has remarked that no animal voluntarily
imitates an action performed by man, until in the ascending scale we
come to monkeys, which are well-known to be ridiculous mockers. Animals,
however, sometimes imitate each others’ actions: thus two species of
wolves, which had been reared by dogs, learned to bark, as does
sometimes the jackal,[55] but whether this can be called voluntary
imitation is another question. From one account which I have read, there
is reason to believe that puppies nursed by cats sometimes learn to lick
their feet and thus to clean their faces: it is at least certain, as I
hear from a perfectly trustworthy friend, that some dogs behave in this
manner. Birds imitate the songs of their parents, and sometimes those of
other birds; and parrots are notorious imitators of any sound which they
often hear.

Hardly any faculty is more important for the intellectual progress of
man than the power of _Attention_. Animals clearly manifest this power,
as when a cat watches by a hole and prepares to spring on its prey. Wild
animals sometimes become so absorbed when thus engaged, that they may be
easily approached. Mr. Bartlett has given me a curious proof how
variable this faculty is in monkeys. A man who trains monkeys to act
used to purchase common kinds from the Zoological Society at the price
of five pounds for each; but he offered to give double the price, if he
might keep three or four of them for a few days, in order to select one.
When asked how he could possibly so soon learn whether a particular
monkey would turn out a good actor, he answered that it all depended on
their power of attention. If when he was talking and explaining anything
to a monkey, its attention was easily distracted, as by a fly on the
wall or other trifling object, the case was hopeless. If he tried by
punishment to make an inattentive monkey act, it turned sulky. On the
other hand, a monkey which carefully attended to him could always be

It is almost superfluous to state that animals have excellent _Memories_
for persons and places. A baboon at the Cape of Good Hope, as I have
been informed by Sir Andrew Smith, recognised him with joy after an
absence of nine months. I had a dog who was savage and averse to all
strangers, and I purposely tried his memory after an absence of five
years and two days. I went near the stable where he lived, and shouted
to him in my old manner; he showed no joy, but instantly followed me out
walking and obeyed me, exactly as if I had parted with him only
half-an-hour before. A train of old associations, dormant during five
years, had thus been instantaneously awakened in his mind. Even ants, as
P. Huber[56] has clearly shewn, recognised their fellow-ants belonging
to the same community after a separation of four months. Animals can
certainly by some means judge of the intervals of time between recurrent

The _Imagination_ is one of the highest prerogatives of man. By this
faculty he unites, independently of the will, former images and ideas,
and thus creates brilliant and novel results. A poet, as Jean Paul
Richter remarks,[57] “who must reflect whether he shall make a
character say yes or no—to the devil with him; he is only a stupid
corpse.” Dreaming gives us the best notion of this power; as Jean Paul
again says, “The dream is an involuntary art of poetry.” The value of
the products of our imagination depends of course on the number,
accuracy, and clearness of our impressions; on our judgment and taste in
selecting or rejecting the involuntary combinations, and to a certain
extent on our power of voluntarily combining them. As dogs, cats,
horses, and probably all the higher animals, even birds, as is stated on
good authority,[58] have vivid dreams, and this is shewn by their
movements and voice, we must admit that they possess some power of

Of all the faculties of the human mind, it will, I presume, be admitted
that _Reason_ stands at the summit. Few persons any longer dispute that
animals possess some power of reasoning. Animals may constantly be seen
to pause, deliberate, and resolve. It is a significant fact, that the
more the habits of any particular animal are studied by a naturalist,
the more he attributes to reason and the less to unlearnt instincts.[59]
In future chapters we shall see that some animals extremely low in the
scale apparently display a certain amount of reason. No doubt it is
often difficult to distinguish between the power of reason and that of
instinct. Thus Dr. Hayes, in his work on ‘The Open Polar Sea,’
repeatedly remarks that his dogs, instead of continuing to draw the
sledges in a compact body, diverged and separated when they came to thin
ice, so that their weight might be more evenly distributed. This was
often the first warning and notice which the travellers received that
the ice was becoming thin and dangerous. Now, did the dogs act thus from
the experience of each individual, or from the example of the older and
wiser dogs, or from an inherited habit, that is from an instinct? This
instinct might possibly have arisen since the time, long ago, when dogs
were first employed by the natives in drawing their sledges; or the
Arctic wolves, the parent-stock of the Esquimaux dog, may have acquired
this instinct, impelling them not to attack their prey in a close pack
when on thin ice. Questions of this kind are most difficult to answer.

So many facts have been recorded in various works shewing that animals
possess some degree of reason, that I will here give only two or three
instances, authenticated by Rengger, and relating to American monkeys,
which stand low in their order. He states that when he first gave eggs
to his monkeys, they smashed them and thus lost much of their contents;
afterwards they gently hit one end against some hard body, and picked
off the bits of shell with their fingers. After cutting themselves only
once with any sharp tool, they would not touch it again, or would handle
it with the greatest care. Lumps of sugar were often given them wrapped
up in paper; and Rengger sometimes put a live wasp in the paper, so that
in hastily unfolding it they got stung; after this had once happened,
they always first held the packet to their ears to detect any movement
within. Any one who is not convinced by such facts as these, and by what
he may observe with his own dogs, that animals can reason, would not be
convinced by anything that I could add. Nevertheless I will give one
case with respect to dogs, as it rests on two distinct observers, and
can hardly depend on the modification of any instinct.

Mr. Colquhoun[60] winged two wild-ducks, which fell on the opposite side
of a stream; his retriever tried to bring over both at once, but could
not succeed; she then, though never before known to ruffle a feather,
deliberately killed one, brought over the other, and returned for the
dead bird. Col. Hutchinson relates that two partridges were shot at
once, one being killed, the other wounded; the latter ran away, and was
caught by the retriever, who on her return came across the dead bird;
“she stopped, evidently greatly puzzled, and after one or two trials,
finding she could not take it up without permitting the escape of the
winged bird, she considered a moment, then deliberately murdered it by
giving it a severe crunch, and afterwards brought away both together.
This was the only known instance of her ever having wilfully injured any
game.” Here we have reason, though not quite perfect, for the retriever
might have brought the wounded bird first and then returned for the dead
one, as in the case of the two wild-ducks.

The muleteers in S. America say, “I will not give you the mule whose
step is easiest, but _la mas rational_,—the one that reasons best;” and
Humboldt[61] adds, “this popular expression, dictated by long
experience, combats the system of animated machines, better perhaps than
all the arguments of speculative philosophy.”

It has, I think, now been shewn that man and the higher animals,
especially the Primates, have some few instincts in common. All have the
same senses, intuitions and sensations—similar passions, affections,
and emotions, even the more complex ones; they feel wonder and
curiosity; they possess the same faculties of imitation, attention,
memory, imagination, and reason, though in very different degrees.
Nevertheless many authors have insisted that man is separated through
his mental faculties by an impassable barrier from all the lower
animals. I formerly made a collection of above a score of such
aphorisms, but they are not worth giving, as their wide difference and
number prove the difficulty, if not the impossibility, of the attempt.
It has been asserted that man alone is capable of progressive
improvement; that he alone makes use of tools or fire, domesticates
other animals, possesses property, or employs language; that no other
animal is self-conscious, comprehends itself, has the power of
abstraction, or possesses general ideas; that man alone has a sense of
beauty, is liable to caprice, has the feeling of gratitude, mystery,
&c.; believes in God, or is endowed with a conscience. I will hazard a
few remarks on the more important and interesting of these points.

Archbishop Sumner formerly maintained[62] that man alone is capable of
progressive improvement. With animals, looking first to the individual,
every one who has had any experience in setting traps knows that young
animals can be caught much more easily than old ones; and they can be
much more easily approached by an enemy. Even with respect to old
animals, it is impossible to catch many in the same place and in the
same kind of trap, or to destroy them by the same kind of poison; yet it
is improbable that all should have partaken of the poison, and
impossible that all should have been caught in the trap. They must learn
caution by seeing their brethren caught or poisoned. In North America,
where the fur-bearing animals have long been pursued, they exhibit,
according to the unanimous testimony of all observers, an almost
incredible amount of sagacity, caution, and cunning; but trapping has
been there so long carried on that inheritance may have come into play.

If we look to successive generations, or to the race, there is no doubt
that birds and other animals gradually both acquire and lose caution in
relation to man or other enemies;[63] and this caution is certainly in
chief part an inherited habit or instinct, but in part the result of
individual experience. A good observer, Leroy,[64] states that in
districts where foxes are much hunted, the young when they first leave
their burrows are incontestably much more wary than the old ones in
districts where they are not much disturbed.

Our domestic dogs are descended from wolves and jackals,[65] and though
they may not have gained in cunning, and may have lost in waryness and
suspicion, yet they have progressed in certain moral qualities, such as
in affection, trust-worthiness, temper, and probably in general
intelligence. The common rat has conquered and beaten several other
species throughout Europe, in parts of North America, New Zealand, and
recently in Formosa, as well as on the mainland of China. Mr.
Swinhoe,[66] who describes these latter cases, attributes the victory of
the common rat over the large _Mus coninga_ to its superior cunning; and
this latter quality may be attributed to the habitual exercise of all
its faculties in avoiding extirpation by man, as well as to nearly all
the less cunning or weak-minded rats having been successively destroyed
by him. To maintain, independently of any direct evidence, that no
animal during the course of ages has progressed in intellect or other
mental faculties, is to beg the question of the evolution of species.
Hereafter we shall see that, according to Lartet, existing mammals
belonging to several orders have larger brains than their ancient
tertiary prototypes.

It has often been said that no animal uses any tool; but the chimpanzee
in a state of nature cracks a native fruit, somewhat like a walnut, with
a stone.[67] Rengger[68] easily taught an American monkey thus to break
open hard palm-nuts, and afterwards of its own accord it used stones to
open other kinds of nuts, as well as boxes. It thus also removed the
soft rind of fruit that had a disagreeable flavour. Another monkey was
taught to open the lid of a large box with a stick, and afterwards it
used the stick as a lever to move heavy bodies; and I have myself seen a
young orang put a stick into a crevice, slip his hand to the other end,
and use it in the proper manner as a lever. In the cases just mentioned
stones and sticks were employed as implements; but they are likewise
used as weapons. Brehm[69] states, on the authority of the well-known
traveller Schimper, that in Abyssinia when the baboons belonging to one
species (_C. gelada_) descend in troops from the mountains to plunder
the fields, they sometimes encounter troops of another species (_C.
hamadryas_), and then a fight ensues. The Geladas roll down great
stones, which the Hamadryas try to avoid, and then, both species,
making a great uproar, rush furiously against each other. Brehm, when
accompanying the Duke of Coburg-Gotha, aided in an attack with fire-arms
on a troop of baboons in the pass of Mensa in Abyssinia. The baboons in
return rolled so many stones down the mountain, some as large as a man’s
head, that the attackers had to beat a hasty retreat; and the pass was
actually for a time closed against the caravan. It deserves notice that
these baboons thus acted in concert. Mr. Wallace[70] on three occasions
saw female orangs, accompanied by their young, “breaking off branches
and the great spiny fruit of the Durian tree, with every appearance of
rage; causing such a shower of missiles as effectually kept us from
approaching too near the tree.”

In the Zoological Gardens a monkey which had weak teeth used to break
open nuts with a stone; and I was assured by the keepers that this
animal, after using the stone, hid it in the straw, and would not let
any other monkey touch it. Here, then, we have the idea of property; but
this idea is common to every dog with a bone, and to most or all birds
with their nests.

The Duke of Argyll[71] remarks, that the fashioning of an implement for
a special purpose is absolutely peculiar to man; and he considers that
this forms an immeasurable gulf between him and the brutes. It is no
doubt a very important distinction, but there appears to me much truth
in Sir J. Lubbock’s suggestion,[72] that when primeval man first used
flint-stones for any purpose, he would have accidentally splintered
them, and would then have used the sharp fragments. From this step it
would be a small one to intentionally break the flints, and not a very
wide step to rudely fashion them. This latter advance, however, may have
taken long ages, if we may judge by the immense interval of time which
elapsed before the men of the neolithic period took to grinding and
polishing their stone tools. In breaking the flints, as Sir J. Lubbock
likewise remarks, sparks would have been emitted, and in grinding them
heat would have been evolved: “thus the two usual methods of obtaining
fire may have originated.” The nature of fire would have been known in
the many volcanic regions where lava occasionally flows through forests.
The anthropomorphous apes, guided probably by instinct, build for
themselves temporary platforms; but as many instincts are largely
controlled by reason, the simpler ones, such as this of building a
platform, might readily pass into a voluntary and conscious act. The
orang is known to cover itself at night with the leaves of the Pandanus;
and Brehm states that one of his baboons used to protect itself from the
heat of the sun by throwing a straw-mat over its head. In these latter
habits, we probably see the first steps towards some of the simpler
arts; namely rude architecture and dress, as they arose amongst the
early progenitors of man.

_Language._—This faculty has justly been considered as one of the chief
distinctions between man and the lower animals. But man, as a highly
competent judge, Archbishop Whately remarks, “is not the only animal
that can make use of language to express what is passing in his mind,
and can understand, more or less, what is so expressed by another.”[73]
In Paraguay the _Cebus Azaræ_ when excited utters at least six distinct
sounds, which excite in other monkeys similar emotions.[74] The
movements of the features and gestures of monkeys are understood by us,
and they partly understand ours, as Rengger and others declare. It is a
more remarkable fact that the dog, since being domesticated, has learnt
to bark[75] in at least four or five distinct tones. Although barking is
a new art, no doubt the wild species, the parents of the dog, expressed
their feelings by cries of various kinds. With the domesticated dog we
have the bark of eagerness, as in the chase; that of anger; the yelping
or howling bark of despair, as when shut up; that of joy, as when
starting on a walk with his master; and the very distinct one of demand
or supplication, as when wishing for a door or window to be opened.

Articulate language is, however, peculiar to man; but he uses in common
with the lower animals inarticulate cries to express his meaning, aided
by gestures and the movements of the muscles of the face.[76] This
especially holds good with the more simple and vivid feelings, which are
but little connected with our higher intelligence. Our cries of pain,
fear, surprise, anger, together with their appropriate actions, and the
murmur of a mother to her beloved child, are more expressive than any
words. It is not the mere power of articulation that distinguishes man
from other animals, for as every one knows, parrots can talk; but it is
his large power of connecting definite sounds with definite ideas; and
this obviously depends on the development of the mental faculties.

As Horne Tooke, one of the founders of the noble science of philology,
observes, language is an art, like brewing or baking; but writing would
have been a much more appropriate simile. It certainly is not a true
instinct, as every language has to be learnt. It differs, however,
widely from all ordinary arts, for man has an instinctive tendency to
speak, as we see in the babble of our young children; whilst no child
has an instinctive tendency to brew, bake, or write. Moreover, no
philologist now supposes that any language has been deliberately
invented; each has been slowly and unconsciously developed by many
steps. The sounds uttered by birds offer in several respects the nearest
analogy to language, for all the members of the same species utter the
same instinctive cries expressive of their emotions; and all the kinds
that have the power of singing exert this power instinctively; but the
actual song, and even the call-notes, are learnt from their parents or
foster-parents. These sounds, as Daines Barrington[77] has proved, “are
no more innate than language is in man.” The first attempts to sing “may
be compared to the imperfect endeavour in a child to babble.” The young
males continue practising, or, as the bird-catchers say, recording, for
ten or eleven months. Their first essays show hardly a rudiment of the
future song; but as they grow older we can perceive what they are aiming
at; and at last they are said “to sing their song round.” Nestlings
which have learnt the song of a distinct species, as with the
canary-birds educated in the Tyrol, teach and transmit their new song to
their offspring. The slight natural differences of song in the same
species inhabiting different districts may be appositely compared, as
Barrington remarks, “to provincial dialects;” and the songs of allied,
though distinct species may be compared with the languages of distinct
races of man. I have given the foregoing details to shew that an
instinctive tendency to acquire an art is not a peculiarity confined to

With respect to the origin of articulate language, after having read on
the one side the highly interesting works of Mr. Hensleigh Wedgwood, the
Rev. F. Farrar, and Prof. Schleicher,[78] and the celebrated lectures of
Prof. Max Müller on the other side, I cannot doubt that language owes
its origin to the imitation and modification, aided by signs and
gestures, of various natural sounds, the voices of other animals, and
man’s own instinctive cries. When we treat of sexual selection we shall
see that primeval man, or rather some early progenitor of man, probably
used his voice largely, as does one of the gibbon-apes at the present
day, in producing true musical cadences, that is in singing; we may
conclude from a widely-spread analogy that this power would have been
especially exerted during the courtship of the sexes, serving to express
various emotions, as love, jealousy, triumph, and serving as a challenge
to their rivals. The imitation by articulate sounds of musical cries
might have given rise to words expressive of various complex emotions.
As bearing on the subject of imitation, the strong tendency in our
nearest allies, the monkeys, in microcephalous idiots,[79] and in the
barbarous races of mankind, to imitate whatever they hear deserves
notice. As monkeys certainly understand much that is said to them by
man, and as in a state of nature they utter signal-cries of danger to
their fellows,[80] it does not appear altogether incredible, that some
unusually wise ape-like animal should have thought of imitating the
growl of a beast of prey, so as to indicate to his fellow monkeys the
nature of the expected danger. And this would have been a first step in
the formation of a language.

As the voice was used more and more, the vocal organs would have been
strengthened and perfected through the principle of the inherited
effects of use; and this would have reacted on the power of speech. But
the relation between the continued use of language and the development
of the brain has no doubt been far more important. The mental powers in
some early progenitor of man must have been more highly developed than
in any existing ape, before even the most imperfect form of speech could
have come into use; but we may confidently believe that the continued
use and advancement of this power would have reacted on the mind by
enabling and encouraging it to carry on long trains of thought. A long
and complex train of thought can no more be carried on without the aid
of words, whether spoken or silent, than a long calculation without the
use of figures or algebra. It appears, also, that even ordinary trains
of thought almost require some form of language, for the dumb, deaf, and
blind girl, Laura Bridgman, was observed to use her fingers whilst
dreaming.[81] Nevertheless a long succession of vivid and connected
ideas, may pass through the mind without the aid of any form of
language, as we may infer from the prolonged dreams of dogs. We have,
also, seen that retriever-dogs are able to reason to a certain extent;
and this they manifestly do without the aid of language. The intimate
connection between the brain, as it is now developed in us, and the
faculty of speech, is well shewn by those curious cases of
brain-disease, in which speech is specially affected, as when the power
to remember substantives is lost, whilst other words can be correctly
used.[82] There is no more improbability in the effects of the continued
use of the vocal and mental organs being inherited, than in the case of
handwriting, which depends partly on the structure of the hand and
partly on the disposition of the mind; and handwriting is certainly

Why the organs now used for speech should have been originally perfected
for this purpose, rather than any other organs, it is not difficult to
see. Ants have considerable powers of intercommunication by means of
their antennæ, as shewn by Huber, who devotes a whole chapter to their
language. We might have used our fingers as efficient instruments, for a
person with practice can report to a deaf man every word of a speech
rapidly delivered at a public meeting; but the loss of our hands, whilst
thus employed, would have been a serious inconvenience. As all the
higher mammals possess vocal organs constructed on the same general
plan with ours, and which are used as a means of communication, it was
obviously probable, if the power of communication had to be improved,
that these same organs would have been still further developed; and this
has been effected by the aid of adjoining and well-adapted parts, namely
the tongue and lips.[84] The fact of the higher apes not using their
vocal organs for speech, no doubt depends on their intelligence not
having been sufficiently advanced. The possession by them of organs,
which with long-continued practice might have been used for speech,
although not thus used, is paralleled by the case of many birds which
possess organs fitted for singing, though they never sing. Thus, the
nightingale and crow have vocal organs similarly constructed, these
being used by the former for diversified song, and by the latter merely
for croaking.[85]

The formation of different languages and of distinct species, and the
proofs that both have been developed through a gradual process, are
curiously the same.[86] But we can trace the origin of many words
further back than in the case of species, for we can perceive that they
have arisen from the imitation of various sounds, as in alliterative
poetry. We find in distinct languages striking homologies due to
community of descent, and analogies due to a similar process of
formation. The manner in which certain letters or sounds change when
others change is very like correlated growth. We have in both cases the
reduplication of parts, the effects of long-continued use, and so forth.
The frequent presence of rudiments, both in languages and in species, is
still more remarkable. The letter _m_ in the word _am_, means _I_; so
that in the expression _I am_, a superfluous and useless rudiment has
been retained. In the spelling also of words, letters often remain as
the rudiments of ancient forms of pronunciation. Languages, like organic
beings, can be classed in groups under groups; and they can be classed
either naturally according to descent, or artificially by other
characters. Dominant languages and dialects spread widely and lead to
the gradual extinction of other tongues. A language, like a species,
when once extinct, never, as Sir C. Lyell remarks, reappears. The same
language never has two birthplaces. Distinct languages may be crossed
or blended together.[87] We see variability in every tongue, and new
words are continually cropping up; but as there is a limit to the powers
of the memory, single words, like whole languages, gradually become
extinct. As Max Müller[88] has well remarked:—“A struggle for life is
constantly going on amongst the words and grammatical forms in each
language. The better, the shorter, the easier forms are constantly
gaining the upper hand, and they owe their success to their own inherent
virtue.” To these more important causes of the survival of certain
words, mere novelty may, I think, be added; for there is in the mind of
man a strong love for slight changes in all things. The survival or
preservation of certain favoured words in the struggle for existence is
natural selection.

The perfectly regular and wonderfully complex construction of the
languages of many barbarous nations has often been advanced as a proof,
either of the divine origin of these languages, or of the high art and
former civilisation of their founders. Thus F. von Schlegel writes: “In
those languages which appear to be at the lowest grade of intellectual
culture, we frequently observe a very high and elaborate degree of art
in their grammatical structure. This is especially the case with the
Basque and the Lapponian, and many of the American languages.”[89] But
it is assuredly an error to speak of any language as an art in the sense
of its having been elaborately and methodically formed. Philologists now
admit that conjugations, declensions, &c., originally existed as
distinct words, since joined together; and as such words express the
most obvious relations between objects and persons, it is not surprising
that they should have been used by the men of most races during the
earliest ages. With respect to perfection, the following illustration
will best shew how easily we may err: a Crinoid sometimes consists of no
less than 150,000 pieces of shell,[90] all arranged with perfect
symmetry in radiating lines; but a naturalist does not consider an
animal of this kind as more perfect than a bilateral one with
comparatively few parts, and with none of these alike, excepting on the
opposite sides of the body. He justly considers the differentiation and
specialisation of organs as the test of perfection. So with languages,
the most symmetrical and complex ought not to be ranked above irregular,
abbreviated, and bastardised languages, which have borrowed expressive
words and useful forms of construction from various conquering, or
conquered, or immigrant races.

From these few and imperfect remarks I conclude that the extremely
complex and regular construction of many barbarous languages, is no
proof that they owe their origin to a special act of creation.[91] Nor,
as we have seen, does the faculty of articulate speech in itself offer
any insuperable objection to the belief that man has been developed from
some lower form.

_Self-consciousness, Individuality, Abstraction, General Ideas, &c._—It
would be useless to attempt discussing these high faculties, which,
according to several recent writers, make the sole and complete
distinction between man and the brutes, for hardly two authors agree in
their definitions. Such faculties could not have been fully developed in
man until his mental powers had advanced to a high standard, and this
implies the use of a perfect language. No one supposes that one of the
lower animals reflects whence he comes or whither he goes,—what is
death or what is life, and so forth. But can we feel sure that an old
dog with an excellent memory and some power of imagination, as shewn by
his dreams, never reflects on his past pleasures in the chase? and this
would be a form of self-consciousness. On the other hand, as Büchner[92]
has remarked, how little can the hard-worked wife of a degraded
Australian savage, who uses hardly any abstract words and cannot count
above four, exert her self-consciousness, or reflect on the nature of
her own existence.

That animals retain their mental individuality is unquestionable. When
my voice awakened a train of old associations in the mind of the
above-mentioned dog, he must have retained his mental individuality,
although every atom of his brain had probably undergone change more than
once during the interval of five years. This dog might have brought
forward the argument lately advanced to crush all evolutionists, and
said, “I abide amid all mental moods and all material changes.... The
teaching that atoms leave their impressions as legacies to other atoms
falling into the places they have vacated is contradictory of the
utterance of consciousness, and is therefore false; but it is the
teaching necessitated by evolutionism, consequently the hypothesis is a
false one.”[93]

_Sense of Beauty._—This sense has been declared to be peculiar to man.
But when we behold male birds elaborately displaying their plumes and
splendid colours before the females, whilst other birds not thus
decorated make no such display, it is impossible to doubt that the
females admire the beauty of their male partners. As women everywhere
deck themselves with these plumes, the beauty of such ornaments cannot
be disputed. The Bower-birds by tastefully ornamenting their
playing-passages with gaily-coloured objects, as do certain
humming-birds their nests, offer additional evidence that they possess a
sense of beauty. So with the song of birds, the sweet strains poured
forth by the males during the season of love are certainly admired by
the females, of which fact evidence will hereafter be given. If female
birds had been incapable of appreciating the beautiful colours, the
ornaments, and voices of their male partners, all the labour and
anxiety exhibited by them in displaying their charms before the females
would have been thrown away; and this it is impossible to admit. Why
certain bright colours and certain sounds should excite pleasure, when
in harmony, cannot, I presume, be explained any more than why certain
flavours and scents are agreeable; but assuredly the same colours and
the same sounds are admired by us and by many of the lower animals.

The taste for the beautiful, at least as far as female beauty is
concerned, is not of a special nature in the human mind; for it differs
widely in the different races of man, as will hereafter be shewn, and is
not quite the same even in the different nations of the same race.
Judging from the hideous ornaments and the equally hideous music admired
by most savages, it might be urged that their æsthetic faculty was not
so highly developed as in certain animals, for instance, in birds.
Obviously no animal would be capable of admiring such scenes as the
heavens at night, a beautiful landscape, or refined music; but such high
tastes, depending as they do on culture and complex associations, are
not enjoyed by barbarians or by uneducated persons.

Many of the faculties, which have been of inestimable service to man for
his progressive advancement, such as the powers of the imagination,
wonder, curiosity, an undefined sense of beauty, a tendency to
imitation, and the love of excitement or novelty, could not fail to have
led to the most capricious changes of customs and fashions. I have
alluded to this point, because a recent writer[94] has oddly fixed on
Caprice “as one of the most remarkable and typical differences between
savages and brutes.” But not only can we perceive how it is that roan is
capricious, but the lower animals are, as we shall hereafter see,
capricious in their affections, aversions, and sense of beauty. There is
also good reason to suspect that they love novelty, for its own sake.

_Belief in God—Religion._—There is no evidence that man was
aboriginally endowed with the ennobling belief in the existence of an
Omnipotent God. On the contrary there is ample evidence, derived not
from hasty travellers, but from men who have long resided with savages,
that numerous races have existed and still exist, who have no idea of
one or more gods, and who have no words in their languages to express
such an idea.[95] The question is of course wholly distinct from that
higher one, whether there exists a Creator and Ruler of the universe;
and this has been answered in the affirmative by the highest intellects
that have ever lived.

If, however, we include under the term “religion” the belief in unseen
or spiritual agencies, the case is wholly different; for this belief
seems to be almost universal with the less civilised races. Nor is it
difficult to comprehend how it arose. As soon as the important faculties
of the imagination, wonder, and curiosity, together with some power of
reasoning, had become partially developed, man would naturally have
craved to understand what was passing around him, and have vaguely
speculated on his own existence. As Mr. M’Lennan[96] has remarked,
“Some explanation of the phenomena of life, a man must feign for
himself; and to judge from the universality of it, the simplest
hypothesis, and the first to occur to men, seems to have been that
natural phenomena are ascribable to the presence in animals, plants, and
things, and in the forces of nature, of such spirits prompting to action
as men are conscious they themselves possess.” It is probable, as Mr.
Tylor has clearly shewn, that dreams may have first given rise to the
notion of spirits; for savages do not readily distinguish between
subjective and objective impressions. When a savage dreams, the figures
which appear before him are believed to have come from a distance and to
stand over him; or “the soul of the dreamer goes out on its travels, and
comes home with a remembrance of what it has seen.”[97] But until the
above-named faculties of imagination, curiosity, reason, &c., had been
fairly well developed in the mind of man, his dreams would not have led
him to believe in spirits, any more than in the case of a dog.

The tendency in savages to imagine that natural objects and agencies
are animated by spiritual or living essences, is perhaps illustrated by
a little fact which I once noticed: my dog, a full-grown and very
sensible animal, was lying on the lawn during a hot and still day; but
at a little distance a slight breeze occasionally moved an open parasol,
which would have been wholly disregarded by the dog, had any one stood
near it. As it was, every time that the parasol slightly moved, the dog
growled fiercely and barked. He must, I think, have reasoned to himself
in a rapid and unconscious manner, that movement without any apparent
cause indicated the presence of some strange living agent, and no
stranger had a right to be on his territory.

The belief in spiritual agencies would easily pass into the belief in
the existence of one or more gods. For savages would naturally attribute
to spirits the same passions, the same love of vengeance or simplest
form of justice, and the same affections which they themselves
experienced. The Fuegians appear to be in this respect in an
intermediate condition, for when the surgeon on board the “Beagle” shot
some young ducklings as specimens, York Minster declared in the most
solemn manner, “Oh! Mr. Bynoe, much rain, much snow, blow much;” and
this was evidently a retributive punishment for wasting human food. So
again he related how, when his brother killed a “wild man,” storms long
raged, much rain and snow fell. Yet we could never discover that the
Fuegians believed in what we should call a God, or practised any
religious rites; and Jemmy Button, with justifiable pride, stoutly
maintained that there was no devil in his land. This latter assertion is
the more remarkable, as with savages the belief in bad spirits is far
more common than the belief in good spirits.

The feeling of religious devotion is a highly complex one, consisting of
love, complete submission to an exalted and mysterious superior, a
strong sense of dependence,[98] fear, reverence, gratitude, hope for the
future, and perhaps other elements. No being could experience so complex
an emotion until advanced in his intellectual and moral faculties to at
least a moderately high level. Nevertheless we see some distant approach
to this state of mind, in the deep love of a dog for his master,
associated with complete submission, some fear, and perhaps other
feelings. The behaviour of a dog when returning to his master after an
absence, and, as I may add, of a monkey to his beloved keeper, is widely
different from that towards their fellows. In the latter case the
transports of joy appear to be somewhat less, and the sense of equality
is shewn in every action. Professor Braubach[99] goes so far as to
maintain that a dog looks on his master as on a god.

The same high mental faculties which first led man to believe in unseen
spiritual agencies, then in fetishism, polytheism, and ultimately in
monotheism, would infallibly lead him, as long as his reasoning powers
remained poorly developed, to various strange superstitions and customs.
Many of these are terrible to think of—such as the sacrifice of human
beings to a blood-loving god; the trial of innocent persons by the
ordeal of poison or fire; witchcraft, &c.—yet it is well occasionally
to reflect on these superstitions, for they shew us what an infinite
debt of gratitude we owe to the improvement of our reason, to science,
and our accumulated knowledge.[100] As Sir J. Lubbock has well
observed, “it is not too much to say that the horrible dread of unknown
evil hangs like a thick cloud over savage life, and embitters every
pleasure.” These miserable and indirect consequences of our highest
faculties may be compared with the incidental and occasional mistakes of
the instincts of the lower animals.



  The moral sense—Fundamental proposition—The qualities of
  social animals—Origin of sociability—Struggle between opposed
  instincts—Man a social animal—The more enduring social
  instincts conquer other less persistent instincts—The social
  virtues alone regarded by savages—The self-regarding virtues
  acquired at a later stage of development—The importance of the
  judgment of the members of the same community on
  conduct—Transmission of moral tendencies—Summary.

I fully subscribe to the judgment of those writers[101] who maintain
that of all the differences between man and the lower animals, the moral
sense or conscience is by far the most important. This sense, as
Mackintosh[102] remarks, “has a rightful supremacy over every other
principle of human action;” it is summed up in that short but imperious
word _ought_, so full of high significance. It is the most noble of all
the attributes of man, leading him without a moment’s hesitation to risk
his life for that of a fellow-creature; or after due deliberation,
impelled simply by the deep feeling of right or duty, to sacrifice it in
some great cause. Immanuel Kant exclaims, “Duty! Wondrous thought, that
workest neither by fond insinuation, flattery, nor by any threat, but
merely by holding up thy naked law in the soul, and so extorting for
thyself always reverence, if not always obedience; before whom all
appetites are dumb, however secretly they rebel; whence thy

This great question has been discussed by many writers[104] of
consummate ability; and my sole excuse for touching on it is the
impossibility of here passing it over, and because, as far as I know, no
one has approached it exclusively from the side of natural history. The
investigation possesses, also, some independent interest, as an attempt
to see how far the study of the lower animals can throw light on one of
the highest psychical faculties of man.

The following proposition seems to me in a high degree probable—namely,
that any animal whatever, endowed with well-marked social
instincts,[105] would inevitably acquire a moral sense or conscience, as
soon as its intellectual powers had become as well developed, or nearly
as well developed, as in man. For, _firstly_, the social instincts lead
an animal to take pleasure in the society of its fellows, to feel a
certain amount of sympathy with them, and to perform various services
for them. The services may be of a definite and evidently instinctive
nature; or there may be only a wish and readiness, as with most of the
higher social animals, to aid their fellows in certain general ways. But
these feelings and services are by no means extended to all the
individuals of the same species, only to those of the same association.
_Secondly_, as soon as the mental faculties had become highly developed,
images of all past actions and motives would be incessantly passing
through the brain of each individual; and that feeling of
dissatisfaction which invariably results, as we shall hereafter see,
from any unsatisfied instinct, would arise, as often as it was perceived
that the enduring and always present social instinct had yielded to some
other instinct, at the time stronger, but neither enduring in its
nature, nor leaving behind it a very vivid impression. It is clear that
many instinctive desires, such as that of hunger, are in their nature of
short duration; and after being satisfied are not readily or vividly
recalled. _Thirdly_, after the power of language had been acquired and
the wishes of the members of the same community could be distinctly
expressed, the common opinion how each member ought to act for the
public good, would naturally become to a large extent the guide to
action. But the social instincts would still give the impulse to act for
the good of the community, this impulse being strengthened, directed,
and sometimes even deflected by public opinion, the power of which
rests, as we shall presently see, on instinctive sympathy. _Lastly_,
habit in the individual would ultimately play a very important part in
guiding the conduct of each member; for the social instincts and
impulses, like all other instincts, would be greatly strengthened by
habit, as would obedience to the wishes and judgment of the community.
These several subordinate propositions must now be discussed; and some
of them at considerable length.

It may be well first to premise that I do not wish to maintain that any
strictly social animal, if its intellectual faculties were to become as
active and as highly developed as in man, would acquire exactly the same
moral sense as ours. In the same manner as various animals have some
sense of beauty, though they admire widely different objects, so they
might have a sense of right and wrong, though led by it to follow widely
different lines of conduct. If, for instance, to take an extreme case,
men were reared under precisely the same conditions as hive-bees, there
can hardly be a doubt that our unmarried females would, like the
worker-bees, think it a sacred duty to kill their brothers, and mothers
would strive to kill their fertile daughters; and no one would think of
interfering. Nevertheless the bee, or any other social animal, would in
our supposed case gain, as it appears to me, some feeling of right and
wrong, or a conscience. For each individual would have an inward sense
of possessing certain stronger or more enduring instincts, and others
less strong or enduring; so that there would often be a struggle which
impulse should be followed; and satisfaction or dissatisfaction would be
felt, as past impressions were compared during their incessant passage
through the mind. In this case an inward monitor would tell the animal
that it would have been better to have followed the one impulse rather
than the other. The one course ought to have been followed: the one
would have been right and the other wrong; but to these terms I shall
have to recur.

_Sociability._—Animals of many kinds are social; we find even distinct
species living together, as with some American monkeys, and with the
united flocks of rooks, jackdaws, and starlings. Man shows the same
feeling in his strong love for the dog, which the dog returns with
interest. Every one must have noticed how miserable horses, dogs, sheep,
&c. are when separated from their companions; and what affection at
least the two former kinds show on their reunion. It is curious to
speculate on the feelings of a dog, who will rest peacefully for hours
in a room with his master or any of the family, without the least notice
being taken of him; but if left for a short time by himself, barks or
howls dismally. We will confine our attention to the higher social
animals, excluding insects, although these aid each other in many
important ways. The most common service which the higher animals perform
for each other, is the warning each other of danger by means of the
united senses of all. Every sportsman knows, as Dr. Jaeger remarks,[106]
how difficult it is to approach animals in a herd or troop. Wild horses
and cattle do not, I believe, make any danger-signal; but the attitude
of any one who first discovers an enemy, warns the others. Rabbits stamp
loudly on the ground with their hind-feet as a signal: sheep and chamois
do the same, but with their fore-feet, uttering likewise a whistle. Many
birds and some mammals post sentinels, which in the case of seals are
said[107] generally to be the females. The leader of a troop of monkeys
acts as the sentinel, and utters cries expressive both of danger and of
safety.[108] Social animals perform many little services for each
other: horses nibble, and cows lick each other, on any spot which
itches: monkeys search for each other’s external parasites; and Brehm
states that after a troop of the _Cercopithecus griseo-viridis_ has
rushed through a thorny brake, each monkey stretches itself on a branch,
and another monkey sitting by “conscientiously” examines its fur and
extracts every thorn or burr.

Animals also render more important services to each other: thus wolves
and some other beasts of prey hunt in packs, and aid each other in
attacking their victims. Pelicans fish in concert. The Hamadryas baboons
turn over stones to find insects, &c.; and when they come to a large
one, as many as can stand round, turn it over together and share the
booty. Social animals mutually defend each other. The males of some
ruminants come to the front when there is danger and defend the herd
with their horns. I shall also in a future chapter give cases of two
young wild bulls attacking an old one in concert, and of two stallions
together trying to drive away a third stallion from a troop of mares.
Brehm encountered in Abyssinia a great troop of baboons which were
crossing a valley: some had already ascended the opposite mountain, and
some were still in the valley: the latter were attacked by the dogs, but
the old males immediately hurried down from the rocks, and with mouths
widely opened roared so fearfully, that the dogs precipitately
retreated. They were again encouraged to the attack; but by this time
all the baboons had reascended the heights, excepting a young one, about
six months old, who, loudly calling for aid, climbed on a block of rock
and was surrounded. Now one of the largest males, a true hero, came down
again from the mountain, slowly went to the young one, coaxed him, and
triumphantly led him away—the dogs being too much astonished to make an
attack. I cannot resist giving another scene which was witnessed by this
same naturalist; an eagle seized a young Cercopithecus, which, by
clinging to a branch, was not at once carried off; it cried loudly for
assistance, upon which the other members of the troop with much uproar
rushed to the rescue, surrounded the eagle, and pulled out so many
feathers, that he no longer thought of his prey, but only how to escape.
This eagle, as Brehm remarks, assuredly would never again attack a
monkey in a troop.

It is certain that associated animals have a feeling of love for each
other which is not felt by adult and non-social animals. How far in most
cases they actually sympathise with each other’s pains and pleasures is
more doubtful, especially with respect to the latter. Mr. Buxton,
however, who had excellent means of observation,[109] states that his
macaws, which lived free in Norfolk, took “an extravagant interest” in a
pair with a nest, and whenever the female left it, she was surrounded by
a troop “screaming horrible acclamations in her honour.” It is often
difficult to judge whether animals have any feeling for each other’s
sufferings. Who can say what cows feel, when they surround and stare
intently on a dying or dead companion? That animals sometimes are far
from feeling any sympathy is too certain; for they will expel a wounded
animal from the herd, or gore or worry it to death. This is almost the
blackest fact in natural history, unless indeed the explanation which
has been suggested is true, that their instinct or reason leads them to
expel an injured companion, lest beasts of prey, including man, should
be tempted to follow the troop. In this case their conduct is not much
worse than that of the North American Indians who leave their feeble
comrades to perish on the plains, or the Feegeans, who, when their
parents get old or fall ill, bury them alive.[110]

Many animals, however, certainly sympathise with each other’s distress
or danger. This is the case even with birds; Capt. Stansbury[111] found
on a salt lake in Utah an old and completely blind pelican, which was
very fat, and must have been long and well fed by his companions. Mr.
Blyth, as he informs me, saw Indian crows feeding two or three of their
companions which were blind; and I have heard of an analogous case with
the domestic cock. We may, if we choose, call these actions instinctive;
but such cases are much too rare for the development of any special
instinct.[112] I have myself seen a dog, who never passed a great friend
of his, a cat which lay sick in a basket, without giving her a few licks
with his tongue, the surest sign of kind feeling in a dog.

It must be called sympathy that leads a courageous dog to fly at any one
who strikes his master, as he certainly will. I saw a person pretending
to beat a lady who had a very timid little dog on her lap, and the trial
had never before been made. The little creature instantly jumped away,
but after the pretended beating was over, it was really pathetic to see
how perseveringly he tried to lick his mistress’s face and comfort her.
Brehm[113] states that when a baboon in confinement was pursued to be
punished, the others tried to protect him. It must have been sympathy in
the cases above given which led the baboons and Cercopitheci to defend
their young comrades from the dogs and the eagle. I will give only one
other instance of sympathetic and heroic conduct in a little American
monkey. Several years ago a keeper at the Zoological Gardens, showed me
some deep and scarcely healed wounds on the nape of his neck, inflicted
on him whilst kneeling on the floor by a fierce baboon. The little
American monkey, who was a warm friend of this keeper, lived in the same
large compartment, and was dreadfully afraid of the great baboon.
Nevertheless, as soon as he saw his friend the keeper in peril, he
rushed to the rescue, and by screams and bites so distracted the baboon
that the man was able to escape, after running great risk, as the
surgeon who attended him thought, of his life.

Besides love and sympathy, animals exhibit other qualities which in us
would be called moral; and I agree with Agassiz[114] that dogs possess
something very like a conscience. They certainly possess some power of
self-command, and this does not appear to be wholly the result of fear.
As Braubach[115] remarks, a dog will refrain from stealing food in the
absence of his master. Dogs have long been accepted as the very type of
fidelity and obedience. All animals living in a body which defend each
other or attack their enemies in concert, must be in some degree
faithful to each other; and those that follow a leader must be in some
degree obedient. When the baboons in Abyssinia[116] plunder a garden,
they silently follow their leader; and if an imprudent young animal
makes a noise, he receives a slap from the others to teach him silence
and obedience; but as soon as they are sure that there is no danger, all
show their joy by much clamour.

With respect to the impulse which leads certain animals to associate
together, and to aid each other in many ways, we may infer that in most
cases they are impelled by the same sense of satisfaction or pleasure
which they experience in performing other instinctive actions; or by the
same sense of dissatisfaction, as in other cases of prevented
instinctive actions. We see this in innumerable instances, and it is
illustrated in a striking manner by the acquired instincts of our
domesticated animals; thus a young shepherd-dog delights in driving and
running round a flock of sheep, but not in worrying them; a young
foxhound delights in hunting a fox, whilst some other kinds of dogs as I
have witnessed, utterly disregard foxes. What a strong feeling of inward
satisfaction must impel a bird, so full of activity, to brood day after
day over her eggs. Migratory birds are miserable if prevented from
migrating, and perhaps they enjoy starting on their long flight. Some
few instincts are determined solely by painful feelings, as by fear,
which leads to self-preservation, or is specially directed against
certain enemies. No one, I presume, can analyse the sensations of
pleasure or pain. In many cases, however, it is probable that instincts
are persistently followed from the mere force of inheritance, without
the stimulus of either pleasure or pain. A young pointer, when it first
scents game, apparently cannot help pointing. A squirrel in a cage who
pats the nuts which it cannot eat, as if to bury them in the ground, can
hardly be thought to act thus either from pleasure or pain. Hence the
common assumption that men must be impelled to every action by
experiencing some pleasure or pain may be erroneous. Although a habit
may be blindly and implicitly followed, independently of any pleasure or
pain felt at the moment, yet if it be forcibly and abruptly checked, a
vague sense of dissatisfaction is generally experienced; and this is
especially true in regard to persons of feeble intellect.

It has often been assumed that animals were in the first place rendered
social, and that they feel as a consequence uncomfortable when separated
from each other, and comfortable whilst together; but it is a more
probable view that these sensations were first developed, in order that
those animals which would profit by living in society, should be induced
to live together. In the same manner as the sense of hunger and the
pleasure of eating were, no doubt, first acquired in order to induce
animals to eat. The feeling of pleasure from society is probably an
extension of the parental or filial affections; and this extension may
be in chief part attributed to natural selection, but perhaps in part to
mere habit. For with those animals which were benefited by living in
close association, the individuals which took the greatest pleasure in
society would best escape various dangers; whilst those that cared least
for their comrades and lived solitary would perish in greater numbers.
With respect to the origin of the parental and filial affections, which
apparently lie at the basis of the social affections, it is hopeless to
speculate; but we may infer that they have been to a large extent
gained through natural selection. So it has almost certainly been with
the unusual and opposite feeling of hatred between the nearest
relations, as with the worker-bees which kill their brother-drones, and
with the queen-bees which kill their daughter-queens; the desire to
destroy, instead of loving, their nearest relations having been here of
service to the community.

The all-important emotion of sympathy is distinct from that of love. A
mother may passionately love her sleeping and passive infant, but she
can then hardly be said to feel sympathy for it. The love of a man for
his dog is distinct from sympathy, and so is that of a dog for his
master. Adam Smith formerly argued, as has Mr. Bain recently, that the
basis of sympathy lies in our strong retentiveness of former states of
pain or pleasure. Hence, “the sight of another person enduring hunger,
cold, fatigue, revives in us some recollection of these states, which
are painful even in idea.” We are thus impelled to relieve the
sufferings of another, in order that our own painful feelings may be at
the same time relieved. In like manner we are led to participate in the
pleasures of others.[117] But I cannot see how this view explains the
fact that sympathy is excited in an immeasurably stronger degree by a
beloved than by an indifferent person. The mere sight of suffering,
independently of love, would suffice to call up in us vivid
recollections and associations. Sympathy may at first have originated in
the manner above suggested; but it seems now to have become an instinct,
which is especially directed towards beloved objects, in the same manner
as fear with animals is especially directed against certain enemies. As
sympathy is thus directed, the mutual love of the members of the same
community will extend its limits. No doubt a tiger or lion feels
sympathy for the sufferings of its own young, but not for any other
animal. With strictly social animals the feeling will be more or less
extended to all the associated members, as we know to be the case. With
mankind selfishness, experience, and imitation probably add, as Mr. Bain
has shewn, to the power of sympathy; for we are led by the hope of
receiving good in return to perform acts of sympathetic kindness to
others; and there can be no doubt that the feeling of sympathy is much
strengthened by habit. In however complex a manner this feeling may have
originated, as it is one of high importance to all those animals which
aid and defend each other, it will have been increased, through natural
selection; for those communities, which included the greatest number of
the most sympathetic members, would flourish best and rear the greatest
number of offspring.

In many cases it is impossible to decide whether certain social
instincts have been acquired through natural selection, or are the
indirect result of other instincts and faculties, such as sympathy,
reason, experience, and a tendency to imitation; or again, whether they
are simply the result of long-continued habit. So remarkable an instinct
as the placing sentinels to warn the community of danger, can hardly
have been the indirect result of any other faculty; it must therefore
have been directly acquired. On the other hand, the habit followed by
the males of some social animals, of defending the community and of
attacking their enemies or their prey in concert, may perhaps have
originated from mutual sympathy; but courage, and in most cases
strength, must have been previously acquired, probably through natural

Of the various instincts and habits, some are much stronger than others,
that is, some either give more pleasure in their performance and more
distress in their prevention than others; or, which is probably quite as
important, they are more persistently followed through inheritance
without exciting any special feeling of pleasure or pain. We are
ourselves conscious that some habits are much more difficult to cure or
change than others. Hence a struggle may often be observed in animals
between different instincts, or between an instinct and some habitual
disposition; as when a dog rushes after a hare, is rebuked, pauses,
hesitates, pursues again or returns ashamed to his master; or as between
the love of a female dog for her young puppies and for her master, for
she may be seen to slink away to them, as if half ashamed of not
accompanying her master. But the most curious instance known to me of
one instinct conquering another, is the migratory instinct conquering
the maternal instinct. The former is wonderfully strong; a confined bird
will at the proper season beat her breast against the wires of her cage,
until it is bare and bloody. It causes young salmon to leap out of the
fresh water, where they could still continue to live, and thus
unintentionally to commit suicide. Every one knows how strong the
maternal instinct is, leading even timid birds to face great danger,
though with hesitation and in opposition to the instinct of
self-preservation. Nevertheless the migratory instinct is so powerful
that late in the autumn swallows and house-martins frequently desert
their tender young, leaving them to perish miserably in their

We can perceive that an instinctive impulse, if it be in any way more
beneficial to a species than some other or opposed instinct, would be
rendered the more potent of the two through natural selection; for the
individuals which had it most strongly developed would survive in larger
numbers. Whether this is the case with the migratory in comparison with
the maternal instinct, may well be doubted. The great persistence or
steady action of the former at certain seasons of the year during the
whole day, may give it for a time paramount force.

_Man a social animal._—Most persons admit that man is a social being.
We see this in his dislike of solitude, and in his wish for society
beyond that of his own family. Solitary confinement is one of the
severest punishments which can be inflicted. Some authors suppose that
man primevally lived in single families; but at the present day, though
single families, or only two or three together, roam the solitudes of
some savage lands, they are always, as far as I can discover, friendly
with other families inhabiting the same district. Such families
occasionally meet in council, and they unite for their common defence.
It is no argument against savage man being a social animal, that the
tribes inhabiting adjacent districts are almost always at war with each
other; for the social instincts never extend to all the individuals of
the same species. Judging from the analogy of the greater number of the
Quadrumana, it is probable that the early ape-like progenitors of man
were likewise social; but this is not of much importance for us.
Although man, as he now exists, has few special instincts, having lost
any which his early progenitors may have possessed, this is no reason
why he should not have retained from an extremely remote period some
degree of instinctive love and sympathy for his fellows. We are indeed
all conscious that we do possess such sympathetic feelings;[119] but our
consciousness does not tell us whether they are instinctive, having
originated long ago in the same manner as with the lower animals, or
whether they have been acquired by each of us during our early years. As
man is a social animal, it is also probable that he would inherit a
tendency to be faithful to his comrades, for this quality is common to
most social animals. He would in like manner possess some capacity for
self-command, and perhaps of obedience to the leader of the community.
He would from an inherited tendency still be willing to defend, in
concert with others, his fellow-men, and would be ready to aid them in
any way which did not too greatly interfere with his own welfare or his
own strong desires.

The social animals which stand at the bottom of the scale are guided
almost exclusively, and those which stand higher in the scale are
largely guided, in the aid which they give to the members of the same
community, by special instincts; but they are likewise in part impelled
by mutual love and sympathy, assisted apparently by some amount of
reason. Although man, as just remarked, has no special instincts to tell
him how to aid his fellow-men, he still has the impulse, and with his
improved intellectual faculties would naturally be much guided in this
respect by reason and experience. Instinctive sympathy would, also,
cause him to value highly the approbation of his fellow-men; for, as Mr.
Bain has clearly shewn,[120] the love of praise and the strong feeling
of glory, and the still stronger horror of scorn and infamy, “are due to
the workings of sympathy.” Consequently man would be greatly influenced
by the wishes, approbation, and blame of his fellow-men, as expressed by
their gestures and language. Thus the social instincts, which must have
been acquired by man in a very rude state, and probably even by his
early ape-like progenitors, still give the impulse to many of his best
actions; but his actions are largely determined by the expressed wishes
and judgment of his fellow-men, and unfortunately still oftener by his
own strong, selfish desires. But as the feelings of love and sympathy
and the power of self-command become strengthened by habit, and as the
power of reasoning becomes clearer so that man can appreciate the
justice of the judgments of his fellow-men, he will feel himself
impelled, independently of any pleasure or pain felt at the moment, to
certain lines of conduct. He may then say, I am the supreme judge of my
own conduct, and in the words of Kant, I will not in my own person
violate the dignity of humanity.

_The more enduring Social Instincts conquer the less Persistent
Instincts._—We have, however, not as yet considered the main point, on
which the whole question of the moral sense hinges. Why should a man
feel that he ought to obey one instinctive desire rather than another?
Why does he bitterly regret if he has yielded to the strong sense of
self-preservation, and has not risked his life to save that of a
fellow-creature; or why does he regret having stolen food from severe

It is evident in the first place, that with mankind the instinctive
impulses have different degrees of strength; a young and timid mother
urged by the maternal instinct will, without a moment’s hesitation, run
the greatest danger for her infant, but not for a mere fellow-creature.
Many a man, or even boy, who never before risked his life for another,
but in whom courage and sympathy were well developed, has, disregarding
the instinct of self-preservation, instantaneously plunged into a
torrent to save a drowning fellow-creature. In this case man is impelled
by the same instinctive motive, which caused the heroic little American
monkey, formerly described, to attack the great and dreaded baboon, to
save his keeper. Such actions as the above appear to be the simple
result of the greater strength of the social or maternal instincts than
of any other instinct or motive; for they are performed too
instantaneously for reflection, or for the sensation of pleasure or
pain; though if prevented distress would be caused.

I am aware that some persons maintain that actions performed
impulsively, as in the above cases, do not come under the dominion of
the moral sense, and cannot be called moral. They confine this term to
actions done deliberately, after a victory over opposing desires, or to
actions prompted by some lofty motive. But it appears scarcely possible
to draw any clear line of distinction of this kind; though the
distinction may be real. As far as exalted motives are concerned, many
instances have been recorded of barbarians, destitute of any feeling of
general benevolence towards mankind, and not guided by any religious
motive, who have deliberately as prisoners sacrificed their lives,[121]
rather than betray their comrades; and surely their conduct ought to be
considered as moral. As far as deliberation and the victory over
opposing motives are concerned, animals may be seen doubting between
opposed instincts, as in rescuing their offspring or comrades from
danger; yet their actions, though done for the good of others, are not
called moral. Moreover, an action repeatedly performed by us, will at
last be done without deliberation or hesitation, and can then hardly be
distinguished from an instinct; yet surely no one will pretend that an
action thus done ceases to be moral. On the contrary, we all feel that
an act cannot be considered as perfect, or as performed in the most
noble manner, unless it be done impulsively, without deliberation or
effort, in the same manner as by a man in whom the requisite qualities
are innate. He who is forced to overcome his fear or want of sympathy
before he acts, deserves, however, in one way higher credit than the man
whose innate disposition leads him to a good act without effort. As we
cannot distinguish between motives, we rank all actions of a certain
class as moral, when they are performed by a moral being. A moral being
is one who is capable of comparing his past and future actions or
motives, and of approving or disapproving of them. We have no reason to
suppose that any of the lower animals have this capacity; therefore
when a monkey faces danger to rescue its comrade, or takes charge of an
orphan-monkey, we do not call its conduct moral. But in the case of man,
who alone can with certainty be ranked as a moral being, actions of a
certain class are called moral, whether performed deliberately after a
struggle with opposing motives, or from the effects of slowly-gained
habit, or impulsively through instinct.

But to return to our more immediate subject; although some instincts are
more powerful than others, thus leading to corresponding actions, yet it
cannot be maintained that the social instincts are ordinarily stronger
in man, or have become stronger through long-continued habit, than the
instincts, for instance, of self-preservation, hunger, lust, vengeance,
&c. Why then does man regret, even though he may endeavour to banish any
such regret, that he has followed the one natural impulse, rather than
the other; and why does he further feel that he ought to regret his
conduct? Man in this respect differs profoundly from the lower animals.
Nevertheless we can, I think, see with some degree of clearness the
reason of this difference.

Man, from the activity of his mental faculties, cannot avoid reflection:
past impressions and images are incessantly passing through his mind
with distinctness. Now with those animals which live permanently in a
body, the social instincts are ever present and persistent. Such animals
are always ready to utter the danger-signal, to defend the community,
and to give aid to their fellows in accordance with their habits; they
feel at all times, without the stimulus of any special passion or
desire, some degree of love and sympathy for them; they are unhappy if
long separated from them, and always happy to be in their company. So it
is with ourselves. A man who possessed no trace of such feelings would
be an unnatural monster. On the other hand, the desire to satisfy
hunger, or any passion, such as vengeance, is in its nature temporary,
and can for a time be fully satisfied. Nor is it easy, perhaps hardly
possible, to call up with complete vividness the feeling, for instance,
of hunger; nor indeed, as has often been remarked, of any suffering. The
instinct of self-preservation is not felt except in the presence of
danger; and many a coward has thought himself brave until he has met his
enemy face to face. The wish for another man’s property is perhaps as
persistent a desire as any that can be named; but even in this case the
satisfaction of actual possession is generally a weaker feeling than the
desire: many a thief, if not an habitual one, after success has wondered
why he stole some article.

Thus, as man cannot prevent old impressions continually repassing
through his mind, he will be compelled to compare the weaker impressions
of, for instance, past hunger, or of vengeance satisfied or danger
avoided at the cost of other men, with the instinct of sympathy and
good-will to his fellows, which is still present and ever in some degree
active in his mind. He will then feel in his imagination that a stronger
instinct has yielded to one which now seems comparatively weak; and then
that sense of dissatisfaction will inevitably be felt with which man is
endowed, like every other animal, in order that his instincts may be
obeyed. The case before given, of the swallow, affords an illustration,
though of a reversed nature, of a temporary though for the time strongly
persistent instinct conquering another instinct which is usually
dominant over all others. At the proper season these birds seem all day
long to be impressed with the desire to migrate; their habits change;
they become restless, are noisy, and congregate in flocks. Whilst the
mother-bird is feeding or brooding over her nestlings, the maternal
instinct is probably stronger than the migratory; but the instinct which
is more persistent gains the victory, and at last, at a moment when her
young ones are not in sight, she takes flight and deserts them. When
arrived at the end of her long journey, and the migratory instinct
ceases to act, what an agony of remorse each bird would feel, if, from
being endowed with great mental activity, she could not prevent the
image continually passing before her mind of her young ones perishing in
the bleak north from cold and hunger.

At the moment of action, man will no doubt be apt to follow the stronger
impulse; and though this may occasionally prompt him to the noblest
deeds, it will far more commonly lead him to gratify his own desires at
the expense of other men. But after their gratification, when past and
weaker impressions are contrasted with the ever-enduring social
instincts, retribution will surely come. Man will then feel dissatisfied
with himself, and will resolve with more or less force to act
differently for the future. This is conscience; for conscience looks
backwards and judges past actions, inducing that kind of
dissatisfaction, which if weak we call regret, and if severe remorse.

These sensations are, no doubt, different from those experienced when
other instincts or desires are left unsatisfied; but every unsatisfied
instinct has its own proper prompting sensation, as we recognise with
hunger, thirst, &c. Man thus prompted, will through long habit acquire
such perfect self-command, that his desires and passions will at last
instantly yield to his social sympathies, and there will no longer be a
struggle between them. The still hungry, or the still revengeful man
will not think of stealing food, or of wreaking his vengeance. It is
possible, or, as we shall hereafter see, even probable, that the habit
of self-command may, like other habits, be inherited. Thus at last man
comes to feel, through acquired and perhaps inherited habit, that it is
best for him to obey his more persistent instincts. The imperious word
_ought_ seems merely to imply the consciousness of the existence of a
persistent instinct, either innate or partly acquired, serving him as a
guide, though liable to be disobeyed. We hardly use the word _ought_ in
a metaphorical sense, when we say hounds ought to hunt, pointers to
point, and retrievers to retrieve their game. If they fail thus to act,
they fail in their duty and act wrongly.

If any desire or instinct, leading to an action opposed to the good of
others, still appears to a man, when recalled to mind, as strong as, or
stronger than, his social instinct, he will feel no keen regret at
having followed it; but he will be conscious that if his conduct were
known to his fellows, it would meet with their disapprobation; and few
are so destitute of sympathy as not to feel discomfort when this is
realised. If he has no such sympathy, and if his desires leading to bad
actions are at the time strong, and when recalled are not overmastered
by the persistent social instincts, then he is essentially a bad
man;[122] and the sole restraining motive left is the fear of
punishment, and the conviction that in the long run it would be best for
his own selfish interests to regard the good of others rather than his

It is obvious that every one may with an easy conscience gratify his own
desires, if they do not interfere with his social instincts, that is
with the good of others; but in order to be quite free from
self-reproach, or at least of anxiety, it is almost necessary for him to
avoid the disapprobation, whether reasonable or not, of his fellow men.
Nor must he break through the fixed habits of his life, especially if
these are supported by reason; for if he does, he will assuredly feel
dissatisfaction. He must likewise avoid the reprobation of the one God
or gods, in whom according to his knowledge or superstition he may
believe; but in this case the additional fear of divine punishment often

_The strictly Social Virtues at first alone regarded._—The above view
of the first origin and nature of the moral sense, which tells us what
we ought to do, and of the conscience which reproves us if we disobey
it, accords well with what we see of the early and undeveloped condition
of this faculty in mankind. The virtues which must be practised, at
least generally, by rude men, so that they may associate in a body, are
those which are still recognised as the most important. But they are
practised almost exclusively in relation to the men of the same tribe;
and their opposites are not regarded as crimes in relation to the men of
other tribes. No tribe could hold together if murder, robbery,
treachery, &c., were common; consequently such crimes within the limits
of the same tribe “are branded with everlasting infamy;”[123] but excite
no such sentiment beyond these limits. A North-American Indian is well
pleased with himself, and is honoured by others, when he scalps a man of
another tribe; and a Dyak cuts off the head of an unoffending person
and dries it as a trophy. The murder of infants has prevailed on the
largest scale throughout the world,[124] and has met with no reproach;
but infanticide, especially of females, has been thought to be good for
the tribe, or at least not injurious. Suicide during former times was
not generally considered as a crime,[125] but rather from the courage
displayed as an honourable act; and it is still largely practised by
some semi-civilised nations without reproach, for the loss to a nation
of a single individual is not felt: whatever the explanation may be,
suicide, as I hear from Sir J. Lubbock, is rarely practised by the
lowest barbarians. It has been recorded that an Indian Thug
conscientiously regretted that he had not strangled and robbed as many
travellers as did his father before him. In a rude state of civilisation
the robbery of strangers is, indeed, generally considered as honourable.

The great sin of Slavery has been almost universal, and slaves have
often been treated in an infamous manner. As barbarians do not regard
the opinion of their women, wives are commonly treated like slaves. Most
savages are utterly indifferent to the sufferings of strangers, or even
delight in witnessing them. It is well known that the women and children
of the North-American Indians aided in torturing their enemies. Some
savages take a horrid pleasure in cruelty to animals,[126] and humanity
with them is an unknown virtue. Nevertheless, feelings of sympathy and
kindness are common, especially during sickness, between the members of
the same tribe, and are sometimes extended beyond the limits of the
tribe. Mungo Park’s touching account of the kindness of the negro women
of the interior to him is well known. Many instances could be given of
the noble fidelity of savages towards each other, but not to strangers;
common experience justifies the maxim of the Spaniard, “Never, never
trust an Indian.” There cannot be fidelity without truth; and this
fundamental virtue is not rare between the members of the same tribe:
thus Mungo Park heard the negro women teaching their young children to
love the truth. This, again, is one of the virtues which becomes so
deeply rooted in the mind that it is sometimes practised by savages even
at a high cost, towards strangers; but to lie to your enemy has rarely
been thought a sin, as the history of modern diplomacy too plainly
shews. As soon as a tribe has a recognised leader, disobedience becomes
a crime, and even abject submission is looked at as a sacred virtue.

As during rude times no man can be useful or faithful to his tribe
without courage, this quality has universally been placed in the highest
rank; and although, in civilised countries, a good, yet timid, man may
be far more useful to the community than a brave one, we cannot help
instinctively honouring the latter above a coward, however benevolent.
Prudence, on the other hand, which does not concern the welfare of
others, though a very useful virtue, has never been highly esteemed. As
no man can practise the virtues necessary for the welfare of his tribe
without self-sacrifice, self-command, and the power of endurance, these
qualities have been at all times highly and most justly valued. The
American savage voluntarily submits without a groan to the most horrid
tortures to prove and strengthen his fortitude and courage; and we
cannot help admiring him, or even an Indian Fakir, who, from a foolish
religious motive, swings suspended by a hook buried in his flesh.

The other self-regarding virtues, which do not obviously, though they
may really, affect the welfare of the tribe, have never been esteemed by
savages, though now highly appreciated by civilised nations. The
greatest intemperance with savages is no reproach. Their utter
licentiousness, not to mention unnatural crimes, is something
astounding.[127] As soon, however, as marriage, whether polygamous or
monogamous, becomes common, jealousy will lead to the inculcation of
female virtue; and this being honoured will tend to spread to the
unmarried females. How slowly it spreads to the male sex we see at the
present day. Chastity eminently requires self-command; therefore it has
been honoured from a very early period in the moral history of civilised
man. As a consequence of this, the senseless practice of celibacy has
been ranked from a remote period as a virtue.[128] The hatred of
indecency, which appears to us so natural as to be thought innate, and
which is so valuable an aid to chastity, is a modern virtue,
appertaining exclusively, as Sir G. Staunton remarks,[129] to civilised
life. This is shewn by the ancient religious rites of various nations,
by the drawings on the walls of Pompeii, and by the practices of many

We have now seen that actions are regarded by savages, and were probably
so regarded by primeval man, as good or bad, solely as they affect in an
obvious manner the welfare of the tribe,—not that of the species, nor
that of man as an individual member of the tribe. This conclusion
agrees well with the belief that the so-called moral sense is
aboriginally derived from the social instincts, for both relate at first
exclusively to the community. The chief causes of the low morality of
savages, as judged by our standard, are, firstly, the confinement of
sympathy to the same tribe. Secondly, insufficient powers of reasoning,
so that the bearing of many virtues, especially of the self-regarding
virtues, on the general welfare of the tribe is not recognised. Savages,
for instance, fail to trace the multiplied evils consequent on a want of
temperance, chastity, &c. And, thirdly, weak power of self-command; for
this power has not been strengthened through long-continued, perhaps
inherited, habit, instruction and religion.

I have entered into the above details on the immorality of savages,[130]
because some authors have recently taken a high view of their moral
nature, or have attributed most of their crimes to mistaken
benevolence.[131] These authors appear to rest their conclusion on
savages possessing, as they undoubtedly do possess, and often in a high
degree, those virtues which are serviceable, or even necessary, for the
existence of a tribal community.

_Concluding Remarks._—Philosophers of the derivative[132] school of
morals formerly assumed that the foundation of morality lay in a form of
Selfishness; but more recently in the “Greatest Happiness principle.”
According to the view given above, the moral sense is fundamentally
identical with the social instincts; and in the case of the lower
animals it would be absurd to speak of these instincts as having been
developed from selfishness, or for the happiness of the community. They
have, however, certainly been developed for the general good of the
community. The term, general good, may be defined as the means by which
the greatest possible number of individuals can be reared in full vigour
and health, with all their faculties perfect, under the conditions to
which they are exposed. As the social instincts both of man and the
lower animals have no doubt been developed by the same steps, it would
be advisable, if found practicable, to use the same definition in both
cases, and to take as the test of morality, the general good or welfare
of the community, rather than the general happiness; but this definition
would perhaps require some limitation on account of political ethics.

When a man risks his life to save that of a fellow-creature, it seems
more appropriate to say that he acts for the general good or welfare,
rather than for the general happiness of mankind. No doubt the welfare
and the happiness of the individual usually coincide; and a contented,
happy tribe will flourish better than one that is discontented and
unhappy. We have seen that at an early period in the history of man, the
expressed wishes of the community will have naturally influenced to a
large extent the conduct of each member; and as all wish for happiness,
the “greatest happiness principle” will have become a most important
secondary guide and object; the social instincts, including sympathy,
always serving as the primary impulse and guide. Thus the reproach of
laying the foundation of the most noble part of our nature in the base
principle of selfishness is removed; unless indeed the satisfaction
which every animal feels when it follows its proper instincts, and the
dissatisfaction felt when prevented, be called selfish.

The expression of the wishes and judgment of the members of the same
community, at first by oral and afterwards by written language, serves,
as just remarked, as a most important secondary guide of conduct, in aid
of the social instincts, but sometimes in opposition to them. This
latter fact is well exemplified by the _Law of Honour_, that is the law
of the opinion of our equals, and not of all our countrymen. The breach
of this law, even when the breach is known to be strictly accordant with
true morality, has caused many a man more agony than a real crime. We
recognise the same influence in the burning sense of shame which most of
us have felt even after the interval of years, when calling to mind some
accidental breach of a trifling though fixed rule of etiquette. The
judgment of the community will generally be guided by some rude
experience of what is best in the long run for all the members; but this
judgment will not rarely err from ignorance and from weak powers of
reasoning. Hence the strangest customs and superstitions, in complete
opposition to the true welfare and happiness of mankind, have become
all-powerful throughout the world. We see this in the horror felt by a
Hindoo who breaks his caste, in the shame of a Mahometan woman who
exposes her face, and in innumerable other instances. It would be
difficult to distinguish between the remorse felt by a Hindoo who has
eaten unclean food, from that felt after committing a theft; but the
former would probably be the more severe.

How so many absurd rules of conduct, as well as so many absurd religious
beliefs, have originated we do not know; nor how it is that they have
become, in all quarters of the world, so deeply impressed on the mind
of men; but it is worthy of remark that a belief constantly inculcated
during the early years of life, whilst the brain is impressible, appears
to acquire almost the nature of an instinct; and the very essence of an
instinct is that it is followed independently of reason. Neither can we
say why certain admirable virtues, such as the love of truth, are much
more highly appreciated by some savage tribes than by others;[133] nor,
again, why similar differences prevail even amongst civilised nations.
Knowing how firmly fixed many strange customs and superstitions have
become, we need feel no surprise that the self-regarding virtues should
now appear to us so natural, supported as they are by reason, as to be
thought innate, although they were not valued by man in his early

Notwithstanding many sources of doubt, man can generally and readily
distinguish between the higher and lower moral rules. The higher are
founded on the social instincts, and relate to the welfare of others.
They are supported by the approbation of our fellow-men and by reason.
The lower rules, though some of them when implying self-sacrifice hardly
deserve to be called lower, relate chiefly to self, and owe their origin
to public opinion, when matured by experience and cultivated; for they
are not practised by rude tribes.

As man advances in civilisation, and small tribes are united into larger
communities, the simplest reason would tell each individual that he
ought to extend his social instincts and sympathies to all the members
of the same nation, though personally unknown to him. This point being
once reached, there is only an artificial barrier to prevent his
sympathies extending to the men of all nations and races. If, indeed,
such men are separated from him by great differences in appearance or
habits, experience unfortunately shews us how long it is before we look
at them as our fellow-creatures. Sympathy beyond the confines of man,
that is humanity to the lower animals, seems to be one of the latest
moral acquisitions. It is apparently unfelt by savages, except towards
their pets. How little the old Romans knew of it is shewn by their
abhorrent gladiatorial exhibitions. The very idea of humanity, as far as
I could observe, was new to most of the Gauchos of the Pampas. This
virtue, one of the noblest with which man is endowed, seems to arise
incidentally from our sympathies becoming more tender and more widely
diffused, until they are extended to all sentient beings. As soon as
this virtue is honoured and practised by some few men, it spreads
through instruction and example to the young, and eventually through
public opinion.

The highest stage in moral culture at which we can arrive, is when we
recognise that we ought to control our thoughts, and “not even in inmost
thought to think again the sins that made the past so pleasant to
us.”[134] Whatever makes any bad action familiar to the mind, renders
its performance by so much the easier. As Marcus Aurelius long ago said,
“Such as are thy habitual thoughts, such also will be the character of
thy mind; for the soul is dyed by the thoughts.”[135]

Our great philosopher, Herbert Spencer, has recently explained his views
on the moral sense. He says,[136] “I believe that the experiences of
utility organised and consolidated through all past generations of the
human race, have been producing corresponding modifications, which, by
continued transmission and accumulation, have become in us certain
faculties of moral intuition—certain emotions responding to right and
wrong conduct, which have no apparent basis in the individual
experiences of utility.” There is not the least inherent improbability,
as it seems to me, in virtuous tendencies being more or less strongly
inherited; for, not to mention the various dispositions and habits
transmitted by many of our domestic animals, I have heard of cases in
which a desire to steal and a tendency to lie appeared to run in
families of the upper ranks; and as stealing is so rare a crime in the
wealthy classes, we can hardly account by accidental coincidence for the
tendency occurring in two or three members of the same family. If bad
tendencies are transmitted, it is probable that good ones are likewise
transmitted. Excepting through the principle of the transmission of
moral tendencies, we cannot understand the differences believed to exist
in this respect between the various races of mankind. We have, however,
as yet, hardly sufficient evidence on this head.

Even the partial transmission of virtuous tendencies would be an immense
assistance to the primary impulse derived directly from the social
instincts, and indirectly from the approbation of our fellow-men.
Admitting for the moment that virtuous tendencies are inherited, it
appears probable, at least in such cases as chastity, temperance,
humanity to animals, &c., that they become first impressed on the mental
organisation through habit, instruction, and example, continued during
several generations in the same family, and in a quite subordinate
degree, or not at all, by the individuals possessing such virtues,
having succeeded best in the struggle for life. My chief source of doubt
with respect to any such inheritance, is that senseless customs,
superstitions, and tastes, such as the horror of a Hindoo for unclean
food, ought on the same principle to be transmitted. Although this in
itself is perhaps not less probable than that animals should acquire
inherited tastes for certain kinds of food or fear of certain foes, I
have not met with any evidence in support of the transmission of
superstitious customs or senseless habits.

Finally, the social instincts which no doubt were acquired by man, as by
the lower animals, for the good of the community, will from the first
have given to him some wish to aid his fellows, and some feeling of
sympathy. Such impulses will have served him at a very early period as a
rude rule of right and wrong. But as man gradually advanced in
intellectual power and was enabled to trace the more remote consequences
of his actions; as he acquired sufficient knowledge to reject baneful
customs and superstitions; as he regarded more and more not only the
welfare but the happiness of his fellow-men; as from habit, following on
beneficial experience, instruction, and example, his sympathies became
more tender and widely diffused, so as to extend to the men of all
races, to the imbecile, the maimed, and other useless members of
society, and finally to the lower animals,—so would the standard of his
morality rise higher and higher. And it is admitted by moralists of the
derivative school and by some intuitionists, that the standard of
morality has risen since an early period in the history of man.[137]

As a struggle may sometimes be seen going on between the various
instincts of the lower animals, it is not surprising that there should
be a struggle in man between his social instincts, with their derived
virtues, and his lower, though at the moment, stronger impulses or
desires. This, as Mr. Galton[138] has remarked, is all the less
surprising, as man has emerged from a state of barbarism within a
comparatively recent period. After having yielded to some temptation we
feel a sense of dissatisfaction, analogous to that felt from other
unsatisfied instincts, called in this case conscience; for we cannot
prevent past images and impressions continually passing through our
minds, and these in their weakened state we compare with the
ever-present social instincts, or with habits gained in early youth and
strengthened during our whole lives, perhaps inherited, so that they are
at last rendered almost as strong as instincts. Looking to future
generations, there is no cause to fear that the social instincts will
grow weaker, and we may expect that virtuous habits will grow stronger,
becoming perhaps fixed by inheritance. In this case the struggle between
our higher and lower impulses will be less severe, and virtue will be

_Summary of the two last Chapters._—There can be no doubt that the
difference between the mind of the lowest man and that of the highest
animal is immense. An anthropomorphous ape, if he could take a
dispassionate view of his own case, would admit that though he could
form an artful plan to plunder a garden—though he could use stones for
fighting or for breaking open nuts, yet that the thought of fashioning
a stone into a tool was quite beyond his scope. Still less, as he would
admit, could he follow out a train of metaphysical reasoning, or solve a
mathematical problem, or reflect on God, or admire a grand natural
scene. Some apes, however, would probably declare that they could and
did admire the beauty of the coloured skin and fur of their partners in
marriage. They would admit, that though they could make other apes
understand by cries some of their perceptions and simpler wants, the
notion of expressing definite ideas by definite sounds had never crossed
their minds. They might insist that they were ready to aid their
fellow-apes of the same troop in many ways, to risk their lives for
them, and to take charge of their orphans; but they would be forced to
acknowledge that disinterested love for all living creatures, the most
noble attribute of man, was quite beyond their comprehension.

Nevertheless the difference in mind between man and the higher animals,
great as it is, is certainly one of degree and not of kind. We have seen
that the senses and intuitions, the various emotions and faculties, such
as love, memory, attention, curiosity, imitation, reason, &c., of which
man boasts, may be found in an incipient, or even sometimes in a
well-developed condition, in the lower animals. They are also capable of
some inherited improvement, as we see in the domestic dog compared with
the wolf or jackal. If it be maintained that certain powers, such as
self-consciousness, abstraction, &c., are peculiar to man, it may well
be that these are the incidental results of other highly-advanced
intellectual faculties; and these again are mainly the result of the
continued use of a highly developed language. At what age does the
new-born infant possess the power of abstraction, or become
self-conscious and reflect on its own existence? We cannot answer; nor
can we answer in regard to the ascending organic scale. The half-art and
half-instinct of language still bears the stamp of its gradual
evolution. The ennobling belief in God is not universal with man; and
the belief in active spiritual agencies naturally follows from his other
mental powers. The moral sense perhaps affords the best and highest
distinction between man and the lower animals; but I need not say
anything on this head, as I have so lately endeavoured to shew
that the social instincts,—the prime principle of man’s moral
constitution[139]—with the aid of active intellectual powers and the
effects of habit, naturally lead to the golden rule, “As ye would that
men should do to you, do ye to them likewise;” and this lies at the
foundation of morality.

In a future chapter I shall make some few remarks on the probable steps
and means by which the several mental and moral faculties of man have
been gradually evolved. That this at least is possible ought not to be
denied, when we daily see their development in every infant; and when we
may trace a perfect gradation from the mind of an utter idiot, lower
than that of the lowest animal, to the mind of a Newton.



  Variability of body and mind in man—Inheritance—Causes of
  variability—Laws of variation the same in man as in the lower
  animals—Direct action of the conditions of life—Effects of
  the increased use and disuse of parts—Arrested
  development—Reversion—Correlated variation—Rate of
  increase—Checks to increase—Natural selection—Man the most
  dominant animal in the world—Importance of his corporeal
  structure—The causes which have led to his becoming
  erect—Consequent changes of structure—Decrease in size of the
  canine teeth—Increased size and altered shape of the
  skull—Nakedness—Absence of a tail—Defenceless condition of

We have seen in the first chapter that the homological structure of man,
his embryological development and the rudiments which he still retains,
all declare in the plainest manner that he is descended from some lower
form. The possession of exalted mental powers is no insuperable
objection to this conclusion. In order that an ape-like creature should
have been transformed into man, it is necessary that this early form, as
well as many successive links, should all have varied in mind and body.
It is impossible to obtain direct evidence on this head; but if it can
be shewn that man now varies—that his variations are induced by the
same general causes, and obey the same general laws, as in the case of
the lower animals—there can be little doubt that the preceding
intermediate links varied in a like manner. The variations at each
successive stage of descent must, also, have been in some manner
accumulated and fixed.

The facts and conclusions to be given in this chapter relate almost
exclusively to the probable means by which the transformation of man has
been effected, as far as his bodily structure is concerned. The
following chapter will be devoted to the development of his intellectual
and moral faculties. But the present discussion likewise bears on the
origin of the different races or species of mankind, whichever term may
be preferred.

It is manifest that man is now subject to much variability. No two
individuals of the same race are quite alike. We may compare millions of
faces, and each will be distinct. There is an equally great amount of
diversity in the proportions and dimensions of the various parts of the
body; the length of the legs being one of the most variable points.[140]
Although in some quarters of the world an elongated skull, and in other
quarters a short skull prevails, yet there is great diversity of shape
even within the limits of the same race, as with the aborigines of
America and South Australia,—the latter a race “probably as pure and
homogeneous in blood, customs, and language as any in existence”—and
even with the inhabitants of so confined an area as the Sandwich
Islands.[141] An eminent dentist assures me that there is nearly as much
diversity in the teeth, as in the features. The chief arteries so
frequently run in abnormal courses, that it has been found useful for
surgical purposes to calculate from 12,000 corpses how often each
course prevails.[142] The muscles are eminently variable: thus those of
the foot were found by Prof. Turner[143] not to be strictly alike in any
two out of fifty bodies; and in some the deviations were considerable.
Prof. Turner adds that the power of performing the appropriate movements
must have been modified in accordance with the several deviations. Mr.
J. Wood has recorded[144] the occurrence of 295 muscular variations in
thirty-six subjects, and in another set of the same number no less than
558 variations, reckoning both sides of the body as one. In the last
set, not one body out of the thirty-six was “found totally wanting in
departures from the standard descriptions of the muscular system given
in anatomical text-books.” A single body presented the extraordinary
number of twenty-five distinct abnormalities. The same muscle sometimes
varies in many ways: thus Prof. Macalister describes[145] no less than
twenty distinct variations in the _palmaris accessorius_.

The famous old anatomist, Wolff,[146] insists that the internal viscera
are more variable than the external parts: _Nulla particula est quæ non
aliter et aliter in aliis se habeat hominibus._ He has even written a
treatise on the choice of typical examples of the viscera for
representation. A discussion on the beau-ideal of the liver, lungs,
kidneys, &c., as of the human face divine, sounds strange in our ears.

The variability or diversity of the mental faculties in men of the same
race, not to mention the greater differences between the men of
distinct races, is so notorious that not a word need here be said. So it
is with the lower animals, as has been illustrated by a few examples in
the last chapter. All who have had charge of menageries admit this fact,
and we see it plainly in our dogs and other domestic animals. Brehm
especially insists that each individual monkey of those which he kept
under confinement in Africa had its own peculiar disposition and temper:
he mentions one baboon remarkable for its high intelligence; and the
keepers in the Zoological Gardens pointed out to me a monkey, belonging
to the New World division, equally remarkable for intelligence. Rengger,
also, insists on the diversity in the various mental characters of the
monkeys of the same species which he kept in Paraguay; and this
diversity, as he adds, is partly innate, and partly the result of the
manner in which they have been treated or educated.[147]

I have elsewhere[148] so fully discussed the subject of Inheritance that
I need here add hardly anything. A greater number of facts have been
collected with respect to the transmission of the most trifling, as well
as of the most important characters in man than in any of the lower
animals; though the facts are copious enough with respect to the latter.
So in regard to mental qualities, their transmission is manifest in our
dogs, horses, and other domestic animals. Besides special tastes and
habits, general intelligence, courage, bad and good temper, &c., are
certainly transmitted. With man we see similar facts in almost every
family; and we now know through the admirable labours of Mr. Galton[149]
that genius, which implies a wonderfully complex combination of high
faculties, tends to be inherited; and, on the other hand, it is too
certain that insanity and deteriorated mental powers likewise run in the
same families.

With respect to the causes of variability we are in all cases very
ignorant; but we can see that in man as in the lower animals, they stand
in some relation with the conditions to which each species has been
exposed during several generations. Domesticated animals vary more than
those in a state of nature; and this is apparently due to the
diversified and changing nature of their conditions. The different races
of man resemble in this respect domesticated animals, and so do the
individuals of the same race when inhabiting a very wide area, like that
of America. We see the influence of diversified conditions in the more
civilised nations, the members of which belong to different grades of
rank and follow different occupations, presenting a greater range of
character than the members of barbarous nations. But the uniformity of
savages has often been exaggerated, and in some cases can hardly be said
to exist.[150] It is nevertheless an error to speak of man, even if we
look only to the conditions to which he has been subjected, as “far more
domesticated”[151] than any other animal. Some savage races, such as
the Australians, are not exposed to more diversified conditions than are
many species which have very wide ranges. In another and much more
important respect, man differs widely from any strictly domesticated
animal; for his breeding has not been controlled, either through
methodical or unconscious selection. No race or body of men has been so
completely subjugated by other men, that certain individuals have been
preserved and thus unconsciously selected, from being in some way more
useful to their masters. Nor have certain male and female individuals
been intentionally picked out and matched, except in the well-known case
of the Prussian grenadiers; and in this case man obeyed, as might have
been expected, the law of methodical selection; for it is asserted that
many tall men were reared in the villages inhabited by the grenadiers
with their tall wives.

If we consider all the races of man, as forming a single species, his
range is enormous; but some separate races, as the Americans and
Polynesians, have very wide ranges. It is a well-known law that
widely-ranging species are much more variable than species with
restricted ranges; and the variability of man may with more truth be
compared with that of widely-ranging species, than with that of
domesticated animals.

Not only does variability appear to be induced in man and the lower
animals by the same general causes, but in both the same characters are
affected in a closely analogous manner. This has been proved in such
full detail by Godron and Quatrefages, that I need here only refer to
their works.[152] Monstrosities, which graduate into slight variations,
are likewise so similar in man and the lower animals, that the same
classification and the same terms can be used for both, as may be seen
in Isidore Geoffroy St.-Hilaire’s great work.[153] This is a necessary
consequence of the same laws of change prevailing throughout the animal
kingdom. In my work on the variation of domestic animals, I have
attempted to arrange in a rude fashion the laws of variation under the
following heads:—The direct and definite action of changed conditions,
as shewn by all or nearly all the individuals of the same species
varying in the same manner under the same circumstances. The effects of
the long-continued use or disuse of parts. The cohesion of homologous
parts. The variability of multiple parts. Compensation of growth; but of
this law I have found no good instances in the case of man. The effects
of the mechanical pressure of one part on another; as of the pelvis on
the cranium of the infant in the womb. Arrests of development, leading
to the diminution or suppression of parts. The reappearance of long-lost
characters through reversion. And lastly, correlated variation. All
these so-called laws apply equally to man and the lower animals; and
most of them even to plants. It would be superfluous here to discuss all
of them;[154] but several are so important for us, that they must be
treated at considerable length.

_The direct and definite action of changed conditions._—This is a most
perplexing subject. It cannot be denied that changed conditions produce
some effect, and occasionally a considerable effect, on organisms of all
kinds; and it seems at first probable that if sufficient time were
allowed this would be the invariable result. But I have failed to obtain
clear evidence in favour of this conclusion; and valid reasons may be
urged on the other side, at least as far as the innumerable structures
are concerned, which are adapted for special ends. There can, however,
be no doubt that changed conditions induce an almost indefinite amount
of fluctuating variability, by which the whole organisation is rendered
in some degree plastic.

In the United States, above 1,000,000 soldiers, who served in the late
war, were measured, and the States in which they were born and reared
recorded.[155] From this astonishing number of observations it is proved
that local influences of some kind act directly on stature; and we
further learn that “the State where the physical growth has in great
measure taken place, and the State of birth, which indicates the
ancestry, seem to exert a marked influence on the stature.” For instance
it is established, “that residence in the Western States, during the
years of growth, tends to produce increase of stature.” On the other
hand, it is certain that with sailors, their manner of life delays
growth, as shewn “by the great difference between the statures of
soldiers and sailors at the ages of 17 and 18 years.” Mr. B. A. Gould
endeavoured to ascertain the nature of the influences which thus act on
stature; but he arrived only at negative results, namely, that they did
not relate to climate, the elevation of the land, soil, nor even “in any
controlling degree” to the abundance or need of the comforts of life.
This latter conclusion is directly opposed to that arrived at by
Villermé from the statistics of the height of the conscripts in
different parts of France. When we compare the differences in stature
between the Polynesian chiefs and the lower orders within the same
islands, or between the inhabitants of the fertile volcanic and low
barren coral islands of the same ocean,[156] or again between the
Fuegians on the eastern and western shores of their country, where the
means of subsistence are very different, it is scarcely possible to
avoid the conclusion that better food and greater comfort do influence
stature. But the preceding statements shew how difficult it is to arrive
at any precise result. Dr. Beddoe has lately proved that, with the
inhabitants of Britain, residence in towns and certain occupations have
a deteriorating influence on height; and he infers that the result is to
a certain extent inherited, as is likewise the case in the United
States. Dr. Beddoe further believes that wherever a “race attains its
maximum of physical development, it rises highest in energy and moral

Whether external conditions produce any other direct effect on man is
not known. It might have been expected that differences of climate would
have had a marked influence, as the lungs and kidneys are brought into
fuller activity under a low temperature, and the liver and skin under a
high one.[158] It was formerly thought that the colour of the skin and
the character of the hair were determined by light or heat; and
although it can hardly be denied that some effect is thus produced,
almost all observers now agree that the effect has been very small, even
after exposure during many ages. But this subject will be more properly
discussed when we treat of the different races of mankind. With our
domestic animals there are grounds for believing that cold and damp
directly affect the growth of the hair; but I have not met with any
evidence on this head in the case of man.

_Effects of the increased Use and Disuse of Parts._—It is well known
that use strengthens the muscles in the individual, and complete disuse,
or the destruction of the proper nerve, weakens them. When the eye is
destroyed the optic nerve often becomes atrophied. When an artery is
tied, the lateral channels increase not only in diameter, but in the
thickness and strength of their coats. When one kidney ceases acting
from disease, the other increases in size and does double work. Bones
increase not only in thickness, but in length, from carrying a greater
weight.[159] Different occupations habitually followed lead to changed
proportions in various parts of the body. Thus it was clearly
ascertained by the United States Commission[160] that the legs of the
sailors employed in the late war were longer by 0.217 of an inch than
those of the soldiers, though the sailors were on an average shorter
men; whilst their arms were shorter by 1.09 of an inch, and therefore
out of proportion shorter in relation to their lesser height. This
shortness of the arms is apparently due to their greater use, and is an
unexpected result; but sailors chiefly use their arms in pulling and not
in supporting weights. The girth of the neck and the depth of the instep
are greater, whilst the circumference of the chest, waist, and hips is
less in sailors than in soldiers.

Whether the several foregoing modifications would become hereditary, if
the same habits of life were followed during many generations, is not
known, but is probable. Rengger[161] attributes the thin legs and thick
arms of the Payaguas Indians to successive generations having passed
nearly their whole lives in canoes, with their lower extremities
motionless. Other writers have come to a similar conclusion in other
analogous cases. According to Cranz,[162] who lived for a long time with
the Esquimaux, “the natives believe that ingenuity and dexterity in
seal-catching (their highest art and virtue) is hereditary; there is
really something in it, for the son of a celebrated seal-catcher will
distinguish himself though he lost his father in childhood.” But in this
case it is mental aptitude, quite as much as bodily structure, which
appears to be inherited. It is asserted that the hands of English
labourers are at birth larger than those of the gentry.[163] From the
correlation which exists, at least in some cases,[164] between the
development of the extremities and of the jaws, it is possible that in
those classes which do not labour much with their hands and feet, the
jaws would be reduced in size from this cause. That they are generally
smaller in refined and civilised men than in hard-working men or
savages, is certain. But with savages, as Mr. Herbert Spencer[165] has
remarked, the greater use of the jaws in chewing coarse, uncooked food,
would act in a direct manner on the masticatory muscles and on the bones
to which they are attached. In infants long before birth, the skin on
the soles of the feet is thicker than on any other part of the
body;[166] and it can hardly be doubted that this is due to the
inherited effects of pressure during a long series of generations.

It is familiar to every one that watchmakers and engravers are liable to
become short-sighted, whilst sailors and especially savages are
generally long-sighted. Short-sight and long-sight certainly tend to be
inherited.[167] The inferiority of Europeans, in comparison with
savages, in eyesight and in the other senses, is no doubt the
accumulated and transmitted effect of lessened use during many
generations; for Rengger[168] states that he has repeatedly observed
Europeans, who had been brought up and spent their whole lives with the
wild Indians, who nevertheless did not equal them in the sharpness of
their senses. The same naturalist observes that the cavities in the
skull for the reception of the several sense-organs are larger in the
American aborigines than in Europeans; and this no doubt indicates a
corresponding difference in the dimensions of the organs themselves.
Blumenbach has also remarked on the large size of the nasal cavities in
the skulls of the American aborigines, and connects this fact with their
remarkably acute power of smell. The Mongolians of the plains of
Northern Asia, according to Pallas, have wonderfully perfect senses; and
Prichard believes that the great breadth of their skulls across the
zygomas follows from their highly-developed sense-organs.[169]

The Quechua Indians inhabit the lofty plateaux of Peru, and Alcide
d’Orbigny states[170] that from continually breathing a highly rarefied
atmosphere they have acquired chests and lungs of extraordinary
dimensions. The cells, also, of the lungs are larger and more numerous
than in Europeans. These observations have been doubted; but Mr. D.
Forbes carefully measured many Aymaras, an allied race, living at the
height of between ten and fifteen thousand feet; and he informs me[171]
that they differ conspicuously from the men of all other races seen by
him, in the circumference and length of their bodies. In his table of
measurements, the stature of each man is taken at 1000, and the other
measurements are reduced to this standard. It is here seen that the
extended arms of the Aymaras are shorter than those of Europeans, and
much shorter than those of Negroes. The legs are likewise shorter, and
they present this remarkable peculiarity, that in every Aymara measured
the femur is actually shorter than the tibia. On an average the length
of the femur to that of the tibia is as 211 to 252; whilst in two
Europeans measured at the same time, the femora to the tibiæ were as
244 to 230; and in three Negroes as 258 to 241. The humerus is likewise
shorter relatively to the fore-arm. This shortening of that part of the
limb which is nearest to the body, appears to be, as suggested to me by
Mr. Forbes, a case of compensation in relation with the greatly
increased length of the trunk. The Aymaras present some other singular
points of structure, for instance, the very small projection of the

These men are so thoroughly acclimatised to their cold and lofty abode,
that when formerly carried down by the Spaniards to the low Eastern
plains, and when now tempted down by high wages to the gold-washings,
they suffer a frightful rate of mortality. Nevertheless Mr. Forbes found
a few pure families which had survived during two generations; and he
observed that they still inherited their characteristic peculiarities.
But it was manifest, even without measurement, that these peculiarities
had all decreased; and on measurement their bodies were found not to be
so much elongated as those of the men on the high plateau; whilst their
femora had become somewhat lengthened, as had their tibiæ but in a less
degree. The actual measurements may be seen by consulting Mr. Forbes’
memoir. From these valuable observations, there can, I think, be no
doubt that residence during many generations at a great elevation tends,
both directly and indirectly, to induce inherited modifications in the
proportions of the body.[172]

Although man may not have been much modified during the latter stages of
his existence through the increased or decreased use of parts, the
facts now given shew that his liability in this respect has not been
lost; and we positively know that the same law holds good with the lower
animals. Consequently we may infer, that when at a remote epoch the
progenitors of man were in a transitional state, and were changing from
quadrupeds into bipeds, natural selection would probably have been
greatly aided by the inherited effects of the increased or diminished
use of the different parts of the body.

_Arrests of Development._—Arrested development differs from arrested
growth, as parts in the former state continue to grow whilst still
retaining their early condition. Various monstrosities come under this
head, and some are known to be occasionally inherited, as a
cleft-palate. It will suffice for our purpose to refer to the arrested
brain-development of microcephalous idiots, as described in Vogt’s great
memoir.[173] Their skulls are smaller, and the convolutions of the brain
are less complex than in normal men. The frontal sinus, or the
projection over the eyebrows, is largely developed, and the jaws are
prognathous to an “_effrayant_” degree; so that these idiots somewhat
resemble the lower types of mankind. Their intelligence and most of
their mental faculties are extremely feeble. They cannot acquire the
power of speech, and are wholly incapable of prolonged attention, but
are much given to imitation. They are strong and remarkably active,
continually gamboling and jumping about, and making grimaces. They often
ascend stairs on all-fours; and are curiously fond of climbing up
furniture or trees. We are thus reminded of the delight shewn by almost
all boys in climbing trees; and this again reminds us how lambs and
kids, originally alpine animals, delight to frisk on any hillock,
however small.

_Reversion._—Many of the cases to be here given might have been
introduced under the last heading. Whenever a structure is arrested in
its development, but still continues growing until it closely resembles
a corresponding structure in some lower and adult member of the same
group, we may in one sense consider it as a case of reversion. The lower
members in a group give us some idea how the common progenitor of the
group was probably constructed; and it is hardly credible that a part
arrested at an early phase of embryonic development should be enabled to
continue growing so as ultimately to perform its proper function, unless
it had acquired this power of continued growth during some earlier state
of existence, when the present exceptional or arrested structure was
normal. The simple brain of a microcephalous idiot, in as far as it
resembles that of an ape, may in this sense be said to offer a case of
reversion. There are other cases which come more strictly under our
present heading of reversion. Certain structures, regularly occurring in
the lower members of the group to which man belongs, occasionally make
their appearance in him, though not found in the normal human embryo;
or, if present in the normal human embryo, they become developed in an
abnormal manner, though this manner of development is proper to the
lower members of the same group. These remarks will be rendered clearer
by the following illustrations.

In various mammals the uterus graduates from a double organ with two
distinct orifices and two passages, as in the marsupials, into a single
organ, showing no signs of doubleness except a slight internal fold, as
in the higher apes and man. The rodents exhibit a perfect series of
gradations between these two extreme states. In all mammals the uterus
is developed from two simple primitive tubes, the inferior portions of
which form the cornua; and it is in the words of Dr. Farre “by the
coalescence of the two cornua at their lower extremities that the body
of the uterus is formed in man; while in those animals in which no
middle portion or body exists, the cornua remain ununited. As the
development of the uterus proceeds, the two cornua become gradually
shorter, until at length they are lost, or, as it were, absorbed into
the body of the uterus.” The angles of the uterus are still produced
into cornua, even so high in the scale as in the lower apes, and their
allies the lemurs.

Now in women anomalous cases are not very infrequent, in which the
mature uterus is furnished with cornua, or is partially divided into two
organs; and such cases, according to Owen, repeat “the grade of
concentrative development,” attained by certain rodents. Here perhaps we
have an instance of a simple arrest of embryonic development, with
subsequent growth and perfect functional development, for either side of
the partially double uterus is capable of performing the proper office
of gestation. In other and rarer cases, two distinct uterine cavities
are formed, each having its proper orifice and passage.[174] No such
stage is passed through during the ordinary development of the embryo,
and it is difficult to believe, though perhaps not impossible, that the
two simple, minute, primitive tubes could know how (if such an
expression may be used) to grow into two distinct uteri, each with a
well-constructed orifice and passage, and each furnished with numerous
muscles, nerves, glands and vessels, if they had not formerly passed
through a similar course of development, as in the case of existing
marsupials. No one will pretend that so perfect a structure as the
abnormal double uterus in woman could be the result of mere chance. But
the principle of reversion, by which long-lost dormant structures are
called back into existence, might serve as the guide for the full
development of the organ, even after the lapse of an enormous interval
of time.

Professor Canestrini,[175] after discussing the foregoing and various
analogous cases, arrives at the same conclusion as that just given. He
adduces, as another instance, the malar bone, which, in some of the
Quadrumana and other mammals, normally consists of two portions. This is
its condition in the two-months-old human fœtus; and thus it
sometimes remains, through arrested development, in man when adult, more
especially in the lower prognathous races. Hence Canestrini concludes
that some ancient progenitor of man must have possessed this bone
normally divided into two portions, which subsequently became fused
together. In man the frontal bone consists of a single piece, but in the
embryo and in children, and in almost all the lower mammals, it consists
of two pieces separated by a distinct suture. This suture occasionally
persists, more or less distinctly, in man after maturity, and more
frequently in ancient than in recent crania, especially as Canestrini
has observed in those exhumed from the Drift and belonging to the
brachycephalic type. Here again he comes to the same conclusion as in
the analogous case of the malar bones. In this and other instances
presently to be given, the cause of ancient races approaching the lower
animals in certain characters more frequently than do the modern races,
appears to be that the latter stand at a somewhat greater distance in
the long line of descent from their early semi-human progenitors.

Various other anomalies in man, more or less analogous with the
foregoing, have been advanced by different authors[176] as cases of
reversion; but these seem not a little doubtful, for we have to descend
extremely low in the mammalian series before we find such structures
normally present.[177]

In man the canine teeth are perfectly efficient instruments for
mastication. But their true canine character, as Owen[178] remarks, “is
indicated by the conical form of the crown, which terminates in an
obtuse point, is convex outward and flat or sub-concave within, at the
base of which surface there is a feeble prominence. The conical form is
best expressed in the Melanian races, especially the Australian. The
canine is more deeply implanted, and by a stronger fang than the
incisors.” Nevertheless this tooth no longer serves man as a special
weapon for tearing his enemies or prey; it may, therefore, as far as its
proper function is concerned, be considered as rudimentary. In every
large collection of human skulls some may be found, as Häckel[179]
observes, with the canine teeth projecting considerably beyond the
others in the same manner, but in a less degree, as in the
anthropomorphous apes. In these cases, open spaces between the teeth in
the one jaw are left for the reception of the canines belonging to the
opposite jaw. An interspace of this kind in a Kaffir skull, figured by
Wagner, is surprisingly wide.[180] Considering how few ancient skulls
have been examined in comparison with recent skulls, it is an
interesting fact that in at least three cases the canines project
largely; and in the Naulette jaw they are spoken of as enormous.[181]

The males alone of the anthropomorphous apes have their canines fully
developed; but in the female gorilla, and in a less degree in the female
orang, these teeth project considerably beyond the others; therefore the
fact that women sometimes have, as I have been assured, considerably
projecting canines, is no serious objection to the belief that their
occasional great development in man is a case of reversion to an
ape-like progenitor. He who rejects with scorn the belief that the shape
of his own canines, and their occasional great development in other men,
are due to our early progenitors having been provided with these
formidable weapons, will probably reveal by sneering the line of his
descent. For though he no longer intends, nor has the power, to use
these teeth as weapons, he will unconsciously retract his “snarling
muscles” (thus named by Sir C. Bell)[182] so as to expose them ready for
action, like a dog prepared to fight.

Many muscles are occasionally developed in man, which are proper to the
Quadrumana or other mammals. Professor Vlacovich[183] examined forty
male subjects, and found a muscle, called by him the ischiopubic, in
nineteen of them; in three others there was a ligament which represented
this muscle; and in the remaining eighteen no trace of it. Out of thirty
female subjects this muscle was developed on both sides in only two, but
in three others the rudimentary ligament was present. This muscle,
therefore, appears to be much more common in the male than in the female
sex; and on the principle of the descent of man from some lower form,
its presence can be understood; for it has been detected in several of
the lower animals, and in all of these it serves exclusively to aid the
male in the act of reproduction.

Mr. J. Wood, in his valuable series of papers,[184] has minutely
described a vast number of muscular variations in man, which resemble
normal structures in the lower animals. Looking only to the muscles
which closely resemble those regularly present in our nearest allies,
the Quadrumana, they are too numerous to be here even specified. In a
single male subject, having a strong bodily frame and well-formed skull,
no less than seven muscular variations were observed, all of which
plainly represented muscles proper to various kinds of apes. This man,
for instance, had on both sides of his neck a true and powerful
“_levator claviculæ_,” such as is found in all kinds of apes, and which
is said to occur in about one out of sixty human subjects.[185] Again,
this man had “a special abductor of the metatarsal bone of the fifth
digit, such as Professor Huxley and Mr. Flower have shewn to exist
uniformly in the higher and lower apes.” The hands and arms of man are
eminently characteristic structures, but their muscles are extremely
liable to vary, so as to resemble the corresponding muscles in the lower
animals.[186] Such resemblances are either complete and perfect or
imperfect, yet in this latter case manifestly of a transitional nature.
Certain variations are more common in man, and others in woman, without
our being able to assign any reason. Mr. Wood, after describing numerous
cases, makes the following pregnant remark: “Notable departures from the
ordinary type of the muscular structures run in grooves or directions,
which must be taken to indicate some unknown factor, of much importance
to a comprehensive knowledge of general and scientific anatomy.”[187]

That this unknown factor is reversion to a former state of existence may
be admitted as in the highest degree probable. It is quite incredible
that a man should through mere accident abnormally resemble, in no less
than seven of his muscles, certain apes, if there had been no genetic
connection between them. On the other hand, if man is descended from
some ape-like creature, no valid reason can be assigned why certain
muscles should not suddenly reappear after an interval of many thousand
generations, in the same manner as with horses, asses, and mules,
dark-coloured stripes suddenly reappear on the legs and shoulders, after
an interval of hundreds, or more probably thousands, of generations.

These various cases of reversion are so closely related to those of
rudimentary organs given in the first chapter, that many of them might
have been indifferently introduced in either chapter. Thus a human
uterus furnished with cornua may be said to represent in a rudimentary
condition the same organ in its normal state in certain mammals. Some
parts which are rudimental in man, as the os coccyx in both sexes and
the mammæ in the male sex, are always present; whilst others, such as
the supra-condyloid foramen, only occasionally appear, and therefore
might have been introduced under the head of reversion. These several
reversionary, as well as the strictly rudimentary, structures reveal the
descent of man from some lower form in an unmistakeable manner.

_Correlated Variation._—In man, as in the lower animals, many
structures are so intimately related, that when one part varies so does
another, without our being able, in most cases, to assign any reason. We
cannot say whether the one part governs the other, or whether both are
governed by some earlier developed part. Various monstrosities, as I.
Geoffroy repeatedly insists, are thus intimately connected. Homologous
structures are particularly liable to change together, as we see on the
opposite sides of the body, and in the upper and lower extremities.
Meckel long ago remarked that when the muscles of the arm depart from
their proper type, they almost always imitate those of the leg; and so
conversely with the muscles of the legs. The organs of sight and
hearing, the teeth and hair, the colour of the skin and hair, colour and
constitution, are more or less correlated.[188] Professor Schaaffhausen
first drew attention to the relation apparently existing between a
muscular frame and strongly-pronounced supra-orbital ridges, which are
so characteristic of the lower races of man.

Besides the variations which can be grouped with more or less
probability under the foregoing heads, there is a large class of
variations which may be provisionally called spontaneous, for they
appear, owing to our ignorance, to arise without any exciting cause. It
can, however, be shewn that such variations, whether consisting of
slight individual differences, or of strongly-marked and abrupt
deviations of structure, depend much more on the constitution of the
organism than on the nature of the conditions to which it has been

_Rate of Increase._—Civilised populations have been known under
favourable conditions, as in the United States, to double their number
in twenty-five years; and according to a calculation by Euler, this
might occur in a little over twelve years.[190] At the former rate the
present population of the United States, namely, thirty millions, would
in 657 years cover the whole terraqueous globe so thickly, that four men
would have to stand on each square yard of surface. The primary or
fundamental check to the continued increase of man is the difficulty of
gaining subsistence and of living in comfort. We may infer that this is
the case from what we see, for instance, in the United States, where
subsistence is easy and there is plenty of room. If such means were
suddenly doubled in Great Britain, our number would be quickly doubled.
With civilised nations the above primary check acts chiefly by
restraining marriages. The greater death-rate of infants in the poorest
classes is also very important; as well as the greater mortality at all
ages, and from various diseases, of the inhabitants of crowded and
miserable houses. The effects of severe epidemics and wars are soon
counterbalanced, and more than counterbalanced, in nations placed under
favourable conditions. Emigration also comes in aid as a temporary
check, but not to any great extent with the extremely poor classes.

There is reason to suspect, as Malthus has remarked, that the
reproductive power is actually less in barbarous than in civilised
races. We know nothing positively on this head, for with savages no
census has been taken; but from the concurrent testimony of
missionaries, and of others who have long resided with such people, it
appears that their families are usually small, and large ones rare. This
may be partly accounted for, as it is believed, by the women suckling
their infants for a prolonged period; but it is highly probable that
savages, who often suffer much hardship, and who do not obtain so much
nutritious food as civilised men, would be actually less prolific. I
have shewn in a former work,[191] that all our domesticated quadrupeds
and birds, and all our cultivated plants, are more fertile than the
corresponding species in a state of nature. It is no valid objection to
this conclusion that animals suddenly supplied with an excess of food,
or when rendered very fat, and that most plants when suddenly removed
from very poor to very rich soil, are rendered more or less sterile. We
might, therefore, expect that civilised men, who in one sense are highly
domesticated, would be more prolific than wild men. It is also probable
that the increased fertility of civilised nations would become, as with
our domestic animals, an inherited character: it is at least known that
with mankind a tendency to produce twins runs in families.[192]

Notwithstanding that savages appear to be less prolific than civilised
people, they would no doubt rapidly increase if their numbers were not
by some means rigidly kept down. The Santali, or hill-tribes of India,
have recently afforded a good illustration of this fact; for they have
increased, as shewn by Mr. Hunter,[193] at an extraordinary rate since
vaccination has been introduced, other pestilences mitigated, and war
sternly repressed. This increase, however, would not have been possible
had not these rude people spread into the adjoining districts and worked
for hire. Savages almost always marry; yet there is some prudential
restraint, for they do not commonly marry at the earliest possible age.
The young men are often required to show that they can support a wife,
and they generally have first to earn the price with which to purchase
her from her parents. With savages the difficulty of obtaining
subsistence occasionally limits their number in a much more direct
manner than with civilised people, for all tribes periodically suffer
from severe famines. At such times savages are forced to devour much bad
food, and their health can hardly fail to be injured. Many accounts have
been published of their protruding stomachs and emaciated limbs after
and during famines. They are then, also, compelled to wander much about,
and their infants, as I was assured in Australia, perish in large
numbers. As famines are periodical, depending chiefly on extreme
seasons, all tribes must fluctuate in number. They cannot steadily and
regularly increase, as there is no artificial increase in the supply of
food. Savages when hardly pressed encroach on each other’s territories,
and war is the result; but they are indeed almost always at war with
their neighbours. They are liable to many accidents on land and water in
their search for food; and in some countries they must suffer much from
the larger beasts of prey. Even in India, districts have been
depopulated by the ravages of tigers.

Malthus has discussed these several checks, but he does not lay stress
enough on what is probably the most important of all, namely
infanticide, especially of female infants, and the habit of procuring
abortion. These practices now prevail in many quarters of the world, and
infanticide seems formerly to have prevailed, as Mr. M’Lennan[194] has
shewn, on a still more extensive scale. These practices appear to have
originated in savages recognising the difficulty, or rather the
impossibility of supporting all the infants that are born.
Licentiousness may also be added to the foregoing checks; but this does
not follow from failing means of subsistence; though there is reason to
believe that in some cases (as in Japan) it has been intentionally
encouraged as a means of keeping down the population.

If we look back to an extremely remote epoch, before man had arrived at
the dignity of manhood, he would have been guided more by instinct and
less by reason than are savages at the present time. Our early
semi-human progenitors would not have practised infanticide, for the
instincts of the lower animals are never so perverted as to lead them
regularly to destroy their own offspring. There would have been no
prudential restraint from marriage, and the sexes would have freely
united at an early age. Hence the progenitors of man would have tended
to increase rapidly, but checks of some kind, either periodical or
constant, must have kept down their numbers, even more severely than
with existing savages. What the precise nature of these checks may have
been, we cannot say, any more than with most other animals. We know that
horses and cattle, which are not highly prolific animals, when first
turned loose in South America, increased at an enormous rate. The
slowest breeder of all known animals, namely the elephant, would in a
few thousand years stock the whole world. The increase of every species
of monkey must be checked by some means; but not, as Brehm remarks, by
the attacks of beasts of prey. No one will assume that the actual power
of reproduction in the wild horses and cattle of America, was at first
in any sensible degree increased; or that, as each district became fully
stocked, this same power was diminished. No doubt in this case and in
all others, many checks concur, and different checks under different
circumstances; periodical dearths, depending on unfavourable seasons,
being probably the most important of all. So it will have been with the
early progenitors of man.

_Natural Selection._—We have now seen that man is variable in body and
mind; and that the variations are induced, either directly or
indirectly, by the same general causes, and obey the same general laws,
as with the lower animals. Man has spread widely over the face of the
earth, and must have been exposed, during his incessant migrations,[195]
to the most diversified conditions. The inhabitants of Tierra del
Fuego, the Cape of Good Hope, and Tasmania in the one hemisphere, and of
the Arctic regions in the other, must have passed through many climates
and changed their habits many times, before they reached their present
homes.[196] The early progenitors of man must also have tended, like all
other animals, to have increased beyond their means of subsistence; they
must therefore occasionally have been exposed to a struggle for
existence, and consequently to the rigid law of natural selection.
Beneficial variations of all kinds will thus, either occasionally or
habitually, have been preserved, and injurious ones eliminated. I do not
refer to strongly-marked deviations of structure, which occur only at
long intervals of time, but to mere individual differences. We know, for
instance, that the muscles of our hands and feet, which determine our
powers of movement, are liable, like those of the lower animals,[197] to
incessant variability. If then the ape-like progenitors of man which
inhabited any district, especially one undergoing some change in its
conditions, were divided into two equal bodies, the one half which
included all the individuals best adapted by their powers of movement
for gaining subsistence or for defending themselves, would on an average
survive in greater number and procreate more offspring than the other
and less well endowed half.

Man in the rudest state in which he now exists is the most dominant
animal that has ever appeared on the earth. He has spread more widely
than any other highly organised form; and all others have yielded
before him. He manifestly owes this immense superiority to his
intellectual faculties, his social habits, which lead him to aid and
defend his fellows, and to his corporeal structure. The supreme
importance of these characters has been proved by the final arbitrament
of the battle for life. Through his powers of intellect, articulate
language has been evolved; and on this his wonderful advancement has
mainly depended. He has invented and is able to use various weapons,
tools, traps, &c., with which he defends himself, kills or catches prey,
and otherwise obtains food. He has made rafts or canoes on which to fish
or cross over to neighbouring fertile islands. He has discovered the art
of making fire, by which hard and stringy roots can be rendered
digestible, and poisonous roots or herbs innocuous. This last discovery,
probably the greatest, excepting language, ever made by man, dates from
before the dawn of history. These several inventions, by which man in
the rudest state has become so preeminent, are the direct result of the
development of his powers of observation, memory, curiosity,
imagination, and reason. I cannot, therefore, understand how it is that
Mr. Wallace[198] maintains, that “natural selection could only have
endowed the savage with a brain a little superior to that of an ape.”

Although the intellectual powers and social habits of man are of
paramount importance to him, we must not underrate the importance of his
bodily structure, to which subject the remainder of this chapter will be
devoted. The development of the intellectual and social or moral
faculties will be discussed in the following chapter.

Even to hammer with precision is no easy matter, as every one who has
tried to learn carpentry will admit. To throw a stone with as true an
aim as can a Fuegian in defending himself, or in killing birds, requires
the most consummate perfection in the correlated action of the muscles
of the hand, arm, and shoulder, not to mention a fine sense of touch. In
throwing a stone or spear, and in many other actions, a man must stand
firmly on his feet; and this again demands the perfect coadaptation of
numerous muscles. To chip a flint into the rudest tool, or to form a
barbed spear or hook from a bone, demands the use of a perfect hand;
for, as a most capable judge, Mr. Schoolcraft,[199] remarks, the shaping
fragments of stone into knives, lances, or arrow-heads, shews
“extraordinary ability and long practice.” We have evidence of this in
primeval men having practised a division of labour; each man did not
manufacture his own flint tools or rude pottery; but certain individuals
appear to have devoted themselves to such work, no doubt receiving in
exchange the produce of the chase. Archæologists are convinced that an
enormous interval of time elapsed before our ancestors thought of
grinding chipped flints into smooth tools. A man-like animal who
possessed a hand and arm sufficiently perfect to throw a stone with
precision or to form a flint into a rude tool, could, it can hardly be
doubted, with sufficient practice make almost anything, as far as
mechanical skill alone is concerned, which a civilised man can make. The
structure of the hand in this respect may be compared with that of the
vocal organs, which in the apes are used for uttering various
signal-cries, or, as in one species, musical cadences; but in man
closely similar vocal organs have become adapted through the inherited
effects of use for the utterance of articulate language.

Turning now to the nearest allies of man, and therefore to the best
representatives of our early progenitors, we find that the hands in the
Quadrumana are constructed on the same general pattern as in us, but are
far less perfectly adapted for diversified uses. Their hands do not
serve so well as the feet of a dog for locomotion; as may be seen in
those monkeys which walk on the outer margins of the palms, or on the
backs of their bent fingers, as in the chimpanzee and orang.[200] Their
hands, however, are admirably adapted for climbing trees. Monkeys seize
thin branches or ropes, with the thumb on one side and the fingers and
palm on the other side, in the same manner as we do. They can thus also
carry rather large objects, such as the neck of a bottle, to their
mouths. Baboons turn over stones and scratch up roots with their hands.
They seize nuts, insects, or other small objects with the thumb in
opposition to the fingers, and no doubt they thus extract eggs and the
young from the nests of birds. American monkeys beat the wild oranges on
the branches until the rind is cracked, and then tear it off with the
fingers of the two hands. Other monkeys open mussel-shells with the two
thumbs. With their fingers they pull out thorns and burrs, and hunt for
each other’s parasites. In a state of nature they break open hard fruits
with the aid of stones. They roll down stones or throw them at their
enemies; nevertheless, they perform these various actions clumsily, and
they are quite unable, as I have myself seen, to throw a stone with

It seems to me far from true that because “objects are grasped clumsily”
by monkeys, “a much less specialised organ of prehension” would have
served them[201] as well as their present hands. On the contrary, I see
no reason to doubt that a more perfectly constructed hand would have
been an advantage to them, provided, and it is important to note this,
that their hands had not thus been rendered less well adapted for
climbing trees. We may suspect that a perfect hand would have been
disadvantageous for climbing; as the most arboreal monkeys in the world,
namely Ateles in America and Hylobates in Asia, either have their thumbs
much reduced in size and even rudimentary, or their fingers
partially coherent, so that their hands are converted into mere

As soon as some ancient member in the great series of the Primates came,
owing to a change in its manner of procuring subsistence, or to a change
in the conditions of its native country, to live somewhat less on trees
and more on the ground, its manner of progression would have been
modified; and in this case it would have had to become either more
strictly quadrupedal or bipedal. Baboons frequent hilly and rocky
districts, and only from necessity climb up high trees;[203] and they
have acquired almost the gait of a dog. Man alone has become a biped;
and we can, I think, partly see how he has come to assume his erect
attitude, which forms one of the most conspicuous differences between
him and his nearest allies. Man could not have attained his present
dominant position in the world without the use of his hands which are so
admirably adapted to act in obedience to his will. As Sir C. Bell[204]
insists “the hand supplies all instruments, and by its correspondence
with the intellect gives him universal dominion.” But the hands and arms
could hardly have become perfect enough to have manufactured weapons, or
to have hurled stones and spears with a true aim, as long as they were
habitually used for locomotion and for supporting the whole weight of
the body, or as long as they were especially well adapted, as previously
remarked, for climbing trees. Such rough treatment would also have
blunted the sense of touch, on which their delicate use largely depends.
From these causes alone it would have been an advantage to man to have
become a biped; but for many actions it is almost necessary that both
arms and the whole upper part of the body should be free; and he must
for this end stand firmly on his feet. To gain this great advantage, the
feet have been rendered flat, and the great toe peculiarly modified,
though this has entailed the loss of the power of prehension. It accords
with the principle of the division of physiological labour, which
prevails throughout the animal kingdom, that as the hands became
perfected for prehension, the feet should have become perfected for
support and locomotion. With some savages, however, the foot has not
altogether lost its prehensile power, as shewn by their manner of
climbing trees and of using them in other ways.[205]

If it be an advantage to man to have his hands and arms free and to
stand firmly on his feet, of which there can be no doubt from his
preeminent success in the battle of life, then I can see no reason why
it should not have been advantageous to the progenitors of man to have
become more and more erect or bipedal. They would thus have been better
able to have defended themselves with stones or clubs, or to have
attacked their prey, or otherwise obtained food. The best constructed
individuals would in the long run have succeeded best, and have survived
in larger numbers. If the gorilla and a few allied forms had become
extinct, it might have been argued with great force and apparent truth,
that an animal could not have been gradually converted from a quadruped
into a biped; as all the individuals in an intermediate condition would
have been miserably ill-fitted for progression. But we know (and this is
well worthy of reflection) that several kinds of apes are now actually
in this intermediate condition; and no one doubts that they are on the
whole well adapted for their conditions of life. Thus the gorilla runs
with a sidelong shambling gait, but more commonly progresses by resting
on its bent hands. The long-armed apes occasionally use their arms like
crutches, swinging their bodies forward between them, and some kinds of
Hylobates, without having been taught, can walk or run upright with
tolerable quickness; yet they move awkwardly, and much less securely
than man. We see, in short, with existing monkeys various gradations
between a form of progression strictly like that of a quadruped and that
of a biped or man.

As the progenitors of man became more and more erect, with their hands
and arms more and more modified for prehension and other purposes, with
their feet and legs at the same time modified for firm support and
progression, endless other changes of structure would have been
necessary. The pelvis would have had to be made broader, the spine
peculiarly curved and the head fixed in an altered position, and all
these changes have been attained by man. Prof. Schaaffhausen[206]
maintains that “the powerful mastoid processes of the human skull are
the result of his erect position;” and these processes are absent in the
orang, chimpanzee, &c., and are smaller in the gorilla than in man.
Various other structures might here have been specified, which appear
connected with man’s erect position. It is very difficult to decide how
far all these correlated modifications are the result of natural
selection, and how far of the inherited effects of the increased use of
certain parts, or of the action of one part on another. No doubt these
means of change act and react on each other: thus when certain muscles,
and the crests of bone to which they are attached, become enlarged by
habitual use, this shews that certain fictions are habitually performed
and must be serviceable. Hence the individuals which performed them
best, would tend to survive in greater numbers.

The free use of the arms and hands, partly the cause and partly the
result of man’s erect position, appears to have led in an indirect
manner to other modifications of structure. The early male progenitors
of man were, as previously stated, probably furnished with great canine
teeth; but as they gradually acquired the habit of using stones, clubs,
or other weapons, for fighting with their enemies, they would have used
their jaws and teeth less and less. In this case, the jaws, together
with the teeth, would have become reduced in size, as we may feel sure
from innumerable analogous cases. In a future chapter we shall meet with
a closely-parallel case, in the reduction or complete disappearance of
the canine teeth in male ruminants, apparently in relation with the
development of their horns; and in horses, in relation with their habit
of fighting with their incisor teeth and hoofs.

In the adult male anthropomorphous apes, as Rütimeyer,[207] and others
have insisted, it is precisely the effect which the jaw-muscles by their
great development have produced on the skull, that causes it to differ
so greatly in many respects from that of man, and has given to it “a
truly frightful physiognomy.” Therefore as the jaws and teeth in the
progenitors of man gradually become reduced in size, the adult skull
would have presented nearly the same characters which it offers in the
young of the anthropomorphous apes, and would thus have come to resemble
more nearly that of existing man. A great reduction of the canine teeth
in the males would almost certainly, as we shall hereafter see, have
affected through inheritance the teeth of the females.

As the various mental faculties were gradually developed, the brain
would almost certainly have become larger. No one, I presume, doubts
that the large size of the brain in man, relatively to his body, in
comparison with that of the gorilla or orang, is closely connected with
his higher mental powers. We meet with closely analogous facts with
insects, in which the cerebral ganglia are of extraordinary dimensions
in ants; these ganglia in all the Hymenoptera being many times larger
than in the less intelligent orders, such as beetles.[208] On the other
hand, no one supposes that the intellect of any two animals or of any
two men can be accurately gauged by the cubic contents of their skulls.
It is certain that there may be extraordinary mental activity with an
extremely small absolute mass of nervous matter: thus the wonderfully
diversified instincts, mental powers, and affections of ants are
generally known, yet their cerebral ganglia are not so large as the
quarter of a small pin’s head. Under this latter point of view, the
brain of an ant is one of the most marvellous atoms of matter in the
world, perhaps more marvellous than the brain of man.

The belief that there exists in man some close relation between the size
of the brain and the development of the intellectual faculties is
supported by the comparison of the skulls of savage and civilised races,
of ancient and modern people, and by the analogy of the whole
vertebrate series. Dr. J. Barnard Davis has proved[209] by many careful
measurements, that the mean internal capacity of the skull in Europeans
is 92·3 cubic inches; in Americans 87·5; in Asiatics 87·1; and in
Australians only 81·9 inches. Professor Broca[210] found that skulls
from graves in Paris of the nineteenth century, were larger than those
from vaults of the twelfth century, in the proportion of 1484 to 1426;
and Prichard is persuaded that the present inhabitants of Britain have
“much more capacious brain-cases” than the ancient inhabitants.
Nevertheless it must be admitted that some skulls of very high
antiquity, such as the famous one of Neanderthal, are well developed and
capacious. With respect to the lower animals, M. E. Lartet,[211] by
comparing the crania of tertiary and recent mammals, belonging to the
same groups, has come to the remarkable conclusion that the brain is
generally larger and the convolutions more complex in the more recent
form. On the other hand I have shewn[212] that the brains of domestic
rabbits are considerably reduced in bulk, in comparison with those of
the wild rabbit or hare; and this may be attributed to their having been
closely confined during many generations, so that they have exerted but
little their intellect, instincts, senses, and voluntary movements.

The gradually increasing weight of the brain and skull in man must have
influenced the development of the supporting spinal column, more
especially whilst he was becoming erect. As this change of position was
being brought about, the internal pressure of the brain, will, also,
have influenced the form of the skull; for many facts shew how easily
the skull is thus affected. Ethnologists believe that it is modified by
the kind of cradle in which infants sleep. Habitual spasms of the
muscles and a cicatrix from a severe burn have permanently modified the
facial bones. In young persons whose heads from disease have become
fixed either sideways or backwards, one of the eyes has changed its
position, and the bones of the skull have been modified; and this
apparently results from the brain pressing in a new direction.[213] I
have shewn that with long-eared rabbits, even so trifling a cause as the
lopping forward of one ear drags forward on that side almost every bone
of the skull; so that the bones on the opposite sides no longer strictly
correspond. Lastly, if any animal were to increase or diminish much in
general size, without any change in its mental powers; or if the mental
powers were to be much increased or diminished without any great change
in the size of the body; the shape of the skull would almost certainly
be altered. I infer this from my observations on domestic rabbits, some
kinds of which have become very much larger than the wild animal, whilst
others have retained nearly the same size, but in both cases the brain
has been much reduced relatively to the size of the body. Now I was at
first much surprised by finding that in all these rabbits the skull had
become elongated or dolichocephalic; for instance, of two skulls of
nearly equal breadth, the one from a wild rabbit and the other from a
large domestic kind, the former was only 3·15 and the latter 4·3 inches
in length.[214] One of the most marked distinctions in different races
of man is that the skull in some is elongated, and in others rounded;
and here the explanation suggested by the case of the rabbits may
partially hold good; for Welcker finds that short “men incline more to
brachycephaly, and tall men to dolichocephaly;”[215] and tall men may be
compared with the larger and longer-bodied rabbits, all of which have
elongated skulls, or are dolichocephalic.

From these several facts we can to a certain extent understand the means
through which the great size and more or less rounded form of the skull
has been acquired by man; and these are characters eminently distinctive
of him in comparison with the lower animals.

Another most conspicuous difference between man and the lower animals is
the nakedness of his skin. Whales and dolphins (Cetacea), dugongs
(Sirenia) and the hippopotamus are naked; and this may be advantageous
to them for gliding through the water; nor would it be injurious to them
from the loss of warmth, as the species which inhabit the colder regions
are protected by a thick layer of blubber, serving the same purpose as
the fur of seals and otters. Elephants and rhinoceroses are almost
hairless; and as certain extinct species which formerly lived under an
arctic climate were covered with long wool or hair, it would almost
appear as if the existing species of both genera had lost their hairy
covering from exposure to heat. This appears the more probable, as the
elephants in India which live on elevated and cool districts are more
hairy[216] than those on the lowlands. May we then infer that man became
divested of hair from having aboriginally inhabited some tropical land?
The fact of the hair being chiefly retained in the male sex on the chest
and face, and in both sexes at the junction of all four limbs with the
trunk, favours this inference, assuming that the hair was lost before
man became erect; for the parts which now retain most hair would then
have been most protected from the heat of the sun. The crown of the
head, however, offers a curious exception, for at all times it must have
been one of the most exposed parts, yet it is thickly clothed with hair.
In this respect man agrees with the great majority of quadrupeds, which
generally have their upper and exposed surfaces more thickly clothed
than the lower surface. Nevertheless, the fact that the other members of
the order of Primates, to which man belongs, although inhabiting various
hot regions, are well clothed with hair, generally thickest on the upper
surface,[217] is strongly opposed to the supposition that man became
naked through the action of the sun. I am inclined to believe, as we
shall see under sexual selection, that man, or rather primarily woman,
became divested of hair for ornamental purposes; and according to this
belief it is not surprising that man should differ so greatly in
hairiness from all his lower brethren, for characters gained through
sexual selection often differ in closely-related forms to an
extraordinary degree.

According to a popular impression, the absence of a tail is eminently
distinctive of man; but as those apes which come nearest to man are
destitute of this organ, its disappearance does not especially concern
us. Nevertheless it may be well to own that no explanation, as far as I
am aware, has ever been given of the loss of the tail by certain apes
and man. Its loss, however, is not surprising, for it sometimes differs
remarkably in length in species of the same genera: thus in some species
of Macacus the tail is longer than the whole body, consisting of
twenty-four vertebræ; in others it consists of a scarcely visible stump,
containing only three or four vertebræ. In some kinds of baboons there
are twenty-five, whilst in the mandrill there are ten very small stunted
caudal vertebræ, or, according to Cuvier,[218] sometimes only five. This
great diversity in the structure and length of the tail in animals
belonging to the same genera, and following nearly the same habits of
life, renders it probable that the tail is not of much importance to
them; and if so, we might have expected that it would sometimes have
become more or less rudimentary, in accordance with what we incessantly
see with other structures. The tail almost always tapers towards the end
whether it be long or short; and this, I presume, results from the
atrophy, through disuse, of the terminal muscles together with their
arteries and nerves, leading to the atrophy of the terminal bones. With
respect to the os coccyx, which in man and the higher apes manifestly
consists of the few basal and tapering segments of an ordinary tail, I
have heard it asked how could these have become completely embedded
within the body; but there is no difficulty in this respect, for in many
monkeys the basal segments of the true tail are thus embedded. For
instance, Mr. Murie informs me that in the skeleton of a not full-grown
_Macacus inornatus_, he counted nine or ten caudal vertebræ, which
altogether were only 1·8 inch in length. Of these the three basal ones
appeared to have been embedded; the remainder forming the free part of
the tail, which was only one inch in length, and half an inch in
diameter. Here, then, the three embedded caudal vertebræ plainly
correspond with the four coalesced vertebræ of the human os coccyx.

I have now endeavoured to shew that some of the most distinctive
characters of man have in all probability been acquired, either
directly, or more commonly indirectly, through natural selection. We
should bear in mind that modifications in structure or constitution,
which are of no service to an organism in adapting it to its habits of
life, to the food which it consumes, or passively to the surrounding
conditions, cannot have been thus acquired. We must not, however, be too
confident in deciding what modifications are of service to each being:
we should remember how little we know about the use of many parts, or
what changes in the blood or tissues may serve to fit an organism for a
new climate or some new kind of food. Nor must we forget the principle
of correlation, by which, as Isidore Geoffroy has shewn in the case of
man, many fit-range deviations of structure are tied together.
Independently of correlation, a change in one part often leads through
the increased or decreased use of other parts, to other changes of a
quite unexpected nature. It is also well to reflect on such facts, as
the wonderful growth of galls on plants caused by the poison of an
insect, and on the remarkable changes of colour in the plumage of
parrots when fed on certain fishes, or inoculated with the poison of
toads;[219] for we can thus see that the fluids of the system, if
altered for some special purpose, might induce other strange changes. We
should especially bear in mind that modifications acquired and
continually used during past ages for some useful purpose would probably
become firmly fixed and might be long inherited.

Thus a very large yet undefined extension may safely be given to the
direct and indirect results of natural selection; but I now admit, after
reading the essay by Nägeli on plants, and the remarks by various
authors with respect to animals, more especially those recently made by
Professor Broca, that in the earlier editions of my ‘Origin of Species’
I probably attributed too much to the action of natural selection or the
survival of the fittest. I have altered the fifth edition of the Origin
so as to confine my remarks to adaptive changes of structure. I had not
formerly sufficiently considered the existence of many structures which
appear to be, as far as we can judge, neither beneficial nor injurious;
and this I believe to be one of the greatest oversights as yet detected
in my work. I may be permitted to say as some excuse, that I had two
distinct objects in view, firstly, to shew that species had not been
separately created, and secondly, that natural selection had been the
chief agent of change, though largely aided by the inherited effects of
habit, and slightly by the direct action of the surrounding conditions.
Nevertheless I was not able to annul the influence of my former belief,
then widely prevalent, that each species had been purposely created; and
this led to my tacitly assuming that every detail of structure,
excepting rudiments, was of some special, though unrecognised, service.
Any one with this assumption in his mind would naturally extend the
action of natural selection, either during past or present times, too
far. Some of those who admit the principle of evolution, but reject
natural selection, seem to forget, when criticising my book, that I had
the above two objects in view; hence if I have erred in giving to
natural selection great power, which I am far from admitting, or in
having exaggerated its power, which is in itself probable, I have at
least, as I hope, done good service in aiding to overthrow the dogma of
separate creations.

That all organic beings, including man, present many modifications of
structure which are of no service to them at present, nor have been
formerly, is, as I can now see, probable. We know not what produces the
numberless slight differences between the individuals of each species,
for reversion only carries the problem a few steps backwards; but each
peculiarity must have had its own efficient cause. If these causes,
whatever they may be, were to act more uniformly and energetically
during a lengthened period (and no reason can be assigned why this
should not sometimes occur), the result would probably be not mere
slight individual differences, but well-marked, constant modifications.
Modifications which are in no way beneficial cannot have been kept
uniform through natural selection, though any which were injurious would
have been thus eliminated. Uniformity of character would, however,
naturally follow from, the assumed uniformity of the exciting causes,
and likewise from the free intercrossing of many individuals. The same
organism might acquire in this manner during successive periods
successive modifications, and these would be transmitted in a nearly
uniform state as long as the exciting causes remained the same and there
was free intercrossing. With respect to the exciting causes we can only
say, as when speaking of so-called spontaneous variations, that they
relate much more closely to the constitution of the varying organism,
than to the nature of the conditions to which it has been subjected.

_Conclusion._—In this chapter we have seen that as man at the present
day is liable, like every other animal, to multiform individual
differences or slight variations, so no doubt were the early progenitors
of man; the variations being then as now induced by the same general
causes, and governed by the same general and complex laws. As all
animals tend to multiply beyond their means of subsistence, so it must
have been with the progenitors of man; and this will inevitably have led
to a struggle for existence and to natural selection. This latter
process will have been greatly aided by the inherited effects of the
increased use of parts; these two processes incessantly reacting on each
other. It appears, also, as we shall hereafter see, that various
unimportant characters have been acquired by man through sexual
selection. An unexplained residuum of change, perhaps a large one, must
be left to the assumed uniform action of those unknown agencies, which
occasionally induce strongly-marked and abrupt deviations of structure
in our domestic productions.

Judging from the habits of savages and of the greater number of the
Quadrumana, primeval men, and even the ape-like progenitors of man,
probably lived in society. With strictly social animals, natural
selection sometimes acts indirectly on the individual, through the
preservation of variations which are beneficial only to the community. A
community including a large number of well-endowed individuals increases
in number and is victorious over other and less well-endowed
communities; although each separate member may gain no advantage over
the other members of the same community. With associated insects many
remarkable structures, which are of little or no service to the
individual or its own offspring, such as the pollen-collecting
apparatus, or the sting of the worker-bee, or the great jaws of
soldier-ants, have been thus acquired. With the higher social animals, I
am not aware that any structure has been modified solely for the good of
the community, though some are of secondary service to it. For instance,
the horns of ruminants and the great canine teeth of baboons appear to
have been acquired by the males as weapons for sexual strife, but they
are used in defence of the herd or troop. In regard to certain mental
faculties the case, as we shall see in the following chapter, is wholly
different; for these faculties have been chiefly, or even exclusively,
gained for the benefit of the community; the individuals composing the
community being at the same time indirectly benefited.

It has often been objected to such views as the foregoing, that man is
one of the most helpless and defenceless creatures in the world; and
that during his early and less well-developed condition he would have
been still more helpless. The Duke of Argyll, for instance, insists[220]
that “the human frame has diverged from the structure of brutes, in the
direction of greater physical helplessness and weakness. That is to say,
it is a divergence which of all others it is most impossible to ascribe
to mere natural selection.” He adduces the naked and unprotected state
of the body, the absence of great teeth or claws for defence, the little
strength of man, his small speed in running, and his slight power of
smell, by which to discover food or to avoid danger. To these
deficiencies there might have been added the still more serious loss of
the power of quickly climbing trees, so as to escape from enemies.
Seeing that the unclothed Fuegians can exist under their wretched
climate, the loss of hair would not have been a great injury to primeval
man, if he inhabited a warm country. When we compare defenceless man
with the apes, many of which are provided with formidable canine teeth,
we must remember that these in their fully-developed condition are
possessed by the males alone, being chiefly used by them for fighting
with their rivals; yet the females which are not thus provided, are able
to survive.

In regard to bodily size or strength, we do not know whether man is
descended from some comparatively small species, like the chimpanzee, or
from one as powerful as the gorilla; and, therefore, we cannot say
whether man has become larger and stronger, or smaller and weaker, in
comparison with his progenitors. We should, however, bear in mind that
an animal possessing great size, strength, and ferocity, and which, like
the gorilla, could defend itself from all enemies, would probably,
though not necessarily, have failed to become social; and this would
most effectually have checked the acquirement by man of his higher
mental qualities, such as sympathy and the love of his fellow-creatures.
Hence it might have been an immense advantage to man to have sprung
from some comparatively weak creature.

The slight corporeal strength of man, his little speed, his want of
natural weapons, &c., are more than counterbalanced, firstly by his
intellectual powers, through which he has, whilst still remaining in a
barbarous state, formed for himself weapons, tools, &c., and secondly by
his social qualities which lead him to give aid to his fellow-men and to
receive it in return. No country in the world abounds in a greater
degree with dangerous beasts than Southern Africa; no country presents
more fearful physical hardships than the Arctic regions; yet one of the
puniest races, namely, the Bushmen, maintain themselves in Southern
Africa, as do the dwarfed Esquimaux in the Arctic regions. The early
progenitors of man were, no doubt, inferior in intellect, and probably
in social disposition, to the lowest existing savages; but it is quite
conceivable that they might have existed, or even flourished, if, whilst
they gradually lost their brute-like powers, such as climbing trees,
&c., they at the same time advanced in intellect. But granting that the
progenitors of man were far more helpless and defenceless than any
existing savages, if they had inhabited some warm continent or large
island, such as Australia or New Guinea, or Borneo (the latter island
being now tenanted by the orang), they would not have been exposed to
any special danger. In an area as large as one of these islands, the
competition between tribe and tribe would have been sufficient, under
favourable conditions, to have raised man, through the survival of the
fittest, combined with the inherited effects of habit, to his present
high position in the organic scale.



  The advancement of the intellectual powers through natural
  selection—Importance of imitation—Social and moral
  faculties—Their development within the limits of the same
  tribe—Natural selection as affecting civilised
  nations—Evidence that civilised nations were once barbarous.

The subjects to be discussed in this chapter are of the highest
interest, but are treated by me in a most imperfect and fragmentary
manner. Mr. Wallace, in an admirable paper before referred to,[221]
argues that man after he had partially acquired those intellectual and
moral faculties which distinguish him from the lower animals, would have
been but little liable to have had his bodily structure modified through
natural selection or any other means. For man is enabled through his
mental faculties “to keep with an unchanged body in harmony with the
changing universe.” He has great power of adapting his habits to new
conditions of life. He invents weapons, tools and various stratagems, by
which he procures food and defends himself. When he migrates into a
colder climate he uses clothes, builds sheds, and makes fires; and, by
the aid of fire, cooks food otherwise indigestible. He aids his
fellow-men in many ways, and anticipates future events. Even at a remote
period he practised some subdivision of labour.

The lower animals, on the other hand, must have their bodily structure
modified in order to survive under greatly changed conditions. They must
be rendered stronger, or acquire more effective teeth or claws, in order
to defend themselves from new enemies; or they must be reduced in size
so as to escape detection and danger. When they migrate into a colder
climate they must become clothed with thicker fur, or have their
constitutions altered. If they fail to be thus modified, they will cease
to exist.

The case, however, is widely different, as Mr. Wallace has with justice
insisted, in relation to the intellectual and moral faculties of man.
These faculties are variable; and we have every reason to believe that
the variations tend to be inherited. Therefore, if they were formerly of
high importance to primeval man and to his ape-like progenitors, they
would have been perfected or advanced through natural selection. Of the
high importance of the intellectual faculties there can be no doubt, for
man mainly owes to them his preeminent position in the world. We can
see that, in the rudest state of society, the individuals who were the
most sagacious, who invented and used the best weapons or traps, and who
were best able to defend themselves, would rear the greatest number of
offspring. The tribes which included the largest number of men thus
endowed would increase in number and supplant other tribes. Numbers
depend primarily on the means of subsistence, and this, partly on the
physical nature of the country, but in a much higher degree on the arts
which are there practised. As a tribe increases and is victorious, it is
often still further increased by the absorption of other tribes.[222]
The stature and strength of the men of a tribe are likewise of some
importance for its success, and these depend in part on the nature and
amount of the food which can be obtained. In Europe the men of the
Bronze period were supplanted by a more powerful and, judging from their
sword-handles, larger-handed race;[223] but their success was probably
due in a much higher degree to their superiority in the arts.

All that we know about savages, or may infer from their traditions and
from old monuments, the history of which is quite forgotten by the
present inhabitants, shew that from the remotest times successful tribes
have supplanted other tribes. Relics of extinct or forgotten tribes have
been discovered throughout the civilised regions of the earth, on the
wild plains of America, and on the isolated islands in the Pacific
Ocean. At the present day civilised nations are everywhere supplanting
barbarous nations, excepting where the climate opposes a deadly barrier;
and they succeed mainly, though not exclusively, through their arts,
which are the products of the intellect. It is, therefore, highly
probable that with mankind the intellectual faculties have been
gradually perfected through natural selection; and this conclusion is
sufficient for our purpose. Undoubtedly it would have been very
interesting to have traced the development of each separate faculty from
the state in which it exists in the lower animals to that in which it
exists in man; but neither my ability nor knowledge permit the attempt.

It deserves notice that as soon as the progenitors of man became social
(and this probably occurred at a very early period), the advancement of
the intellectual faculties will have been aided and modified in an
important manner, of which we see only traces in the lower animals,
namely, through the principle of imitation, together with reason and
experience. Apes are much given to imitation, as are the lowest savages;
and the simple fact previously referred to, that after a time no animal
can be caught in the same place by the same sort of trap, shews that
animals learn by experience, and imitate each others’ caution. Now, if
some one man in a tribe, more sagacious than the others, invented a new
snare or weapon, or other means of attack or defence, the plainest
self-interest, without the assistance of much reasoning power, would
prompt the other members to imitate him; and all would thus profit. The
habitual practice of each new art must likewise in some slight degree
strengthen the intellect. If the new invention were an important one,
the tribe would increase in number, spread, and supplant other tribes.
In a tribe thus rendered more numerous there would always be a rather
better chance of the birth of other superior and inventive members. If
such men left children to inherit their mental superiority, the chance
of the birth of still more ingenious members would be somewhat better,
and in a very small tribe decidedly better. Even if they left no
children, the tribe would still include their blood-relations; and it
has been ascertained by agriculturists[224] that by preserving and
breeding from the family of an animal, which when slaughtered was found
to be valuable, the desired character has been obtained.

Turning now to the social and moral faculties. In order that primeval
men, or the ape-like progenitors of man, should have become social, they
must have acquired the same instinctive feelings which impel other
animals to live in a body; and they no doubt exhibited the same general
disposition. They would have felt uneasy when separated from their
comrades, for whom they would have felt some degree of love; they would
have warned each other of danger, and have given mutual aid in attack or
defence. All this implies some degree of sympathy, fidelity, and
courage. Such social qualities, the paramount importance of which to the
lower animals is disputed by no one, were no doubt acquired by the
progenitors of man in a similar manner, namely, through natural
selection, aided by inherited habit. When two tribes of primeval man,
living in the same country, came into competition, if the one tribe
included (other circumstances being equal) a greater number of
courageous, sympathetic, and faithful members, who were always ready to
warn each other of danger, to aid and defend each other, this tribe
would without doubt succeed best and conquer the other. Let it be borne
in mind how all-important, in the never-ceasing wars of savages,
fidelity and courage must be. The advantage which disciplined soldiers
have over undisciplined hordes follows chiefly from the confidence which
each man feels in his comrades. Obedience, as Mr. Bagehot has well
shewn,[225] is of the highest value, for any form of government is
better than none. Selfish and contentious people will not cohere, and
without coherence nothing can be effected. A tribe possessing the above
qualities in a high degree would spread and be victorious over other
tribes; but in the course of time it would, judging from all past
history, be in its turn overcome by some other and still more highly
endowed tribe. Thus the social and moral qualities would tend slowly to
advance and be diffused throughout the world.

But it may be asked, how within the limits of the same tribe did a large
number of members first become endowed with these social and moral
qualities, and how was the standard of excellence raised? It is
extremely doubtful whether the offspring of the more sympathetic and
benevolent parents, or of those which were the most faithful to their
comrades, would be reared in greater number than the children of selfish
and treacherous parents of the same tribe. He who was ready to sacrifice
his life, as many a savage has been, rather than betray his comrades,
would often leave no offspring to inherit his noble nature. The bravest
men, who were always willing to come to the front in war, and who freely
risked their lives for others, would on an average perish in larger
number than other men. Therefore it seems scarcely possible (bearing in
mind that we are not here speaking of one tribe being victorious over
another) that the number of men gifted with such virtues, or that the
standard of their excellence, could be increased through natural
selection, that is, by the survival of the fittest.

Although the circumstances which lead to an increase in the number of
men thus endowed within the same tribe are too complex to be clearly
followed out, we can trace some of the probable steps. In the first
place, as the reasoning powers and foresight of the members became
improved, each man would soon learn from experience that if he aided his
fellow-men, he would commonly receive aid in return. From this low
motive he might acquire the habit of aiding his fellows; and the habit
of performing benevolent actions certainly strengthens the feeling of
sympathy, which gives the first impulse to benevolent actions. Habits,
moreover, followed during many generations probably tend to be

But there is another and much more powerful stimulus to the development
of the social virtues, namely, the praise and the blame of our
fellow-men. The love of approbation and the dread of infamy, as well as
the bestowal of praise or blame, are primarily due, as we have seen in
the third chapter, to the instinct of sympathy; and this instinct no
doubt was originally acquired, like all the other social instincts,
through natural selection. At how early a period the progenitors of man,
in the course of their development, became capable of feeling and being
impelled by the praise or blame of their fellow-creatures, we cannot, of
course, say. But it appears that even dogs appreciate encouragement,
praise, and blame. The rudest savages feel the sentiment of glory, as
they clearly show by preserving the trophies of their prowess, by their
habit of excessive boasting, and even by the extreme care which they
take of their personal appearance and decorations; for unless they
regarded the opinion of their comrades, such habits would be senseless.

They certainly feel shame at the breach of some of their lesser rules;
but how far they experience remorse is doubtful. I was at first
surprised that I could not recollect any recorded instances of this
feeling in savages; and Sir J. Lubbock[226] states that he knows of
none. But if we banish from our minds all cases given in novels and
plays and in death-bed confessions made to priests, I doubt whether many
of us have actually witnessed remorse; though we may have often seen
shame and contrition for smaller offences. Remorse is a deeply hidden
feeling. It is incredible that a savage, who will sacrifice his life
rather than betray his tribe, or one who will deliver himself up as a
prisoner rather than break his parole,[227] would not feel remorse in
his inmost soul, though he might conceal it, if he had failed in a duty
which he held sacred.

We may therefore conclude that primeval man, at a very remote period,
would have been influenced by the praise and blame of his fellows. It is
obvious, that the members of the same tribe would approve of conduct
which appeared to them to be for the general good, and would reprobate
that which appeared evil. To do good unto others—to do unto others as
ye would they should do unto you,—is the foundation-stone of morality.
It is, therefore, hardly possible to exaggerate the importance during
rude times of the love of praise and the dread of blame. A man who was
not impelled by any deep, instinctive feeling, to sacrifice his life for
the good of others, yet was roused to such actions by a sense of glory,
would by his example excite the same wish for glory in other men, and
would strengthen by exercise the noble feeling of admiration. He might
thus do far more good to his tribe than by begetting offspring with a
tendency to inherit his own high character.

With increased experience and reason, man perceives the more remote
consequences of his actions, and the self-regarding virtues, such as
temperance, chastity, &c., which during early times are, as we have
before seen, utterly disregarded, come to be highly esteemed or even
held sacred. I need not, however, repeat what I have said on this head
in the third chapter. Ultimately a highly complex sentiment, having its
first origin in the social instincts, largely guided by the approbation
of our fellow-men, ruled by reason, self-interest, and in later times by
deep religious feelings, confirmed by instruction and habit, all
combined, constitute our moral sense or conscience.

It must not be forgotten that although a high standard of morality gives
but a slight or no advantage to each individual man and his children
over the other men of the same tribe, yet that an advancement in the
standard of morality and an increase in the number of well-endowed men
will certainly give an immense advantage to one tribe over another.
There can be no doubt that a tribe including many members who, from
possessing in a high degree the spirit of patriotism, fidelity,
obedience, courage, and sympathy, were always ready to give aid to each
other and to sacrifice themselves for the common good, would be
victorious over most other tribes; and this would be natural selection.
At all times throughout the world tribes have supplanted other tribes;
and as morality is one element in their success, the standard of
morality and the number of well-endowed men will thus everywhere tend to
rise and increase.

It is, however, very difficult to form any judgment why one particular
tribe and not another has been successful and has risen in the scale of
civilisation. Many savages are in the same condition as when first
discovered several centuries ago. As Mr. Bagehot has remarked, we are
apt to look at progress as the normal rule in human society; but history
refutes this. The ancients did not even entertain the idea; nor do the
oriental nations at the present day. According to another high
authority, Mr. Maine,[228] “the greatest part of mankind has never
shewn a particle of desire that its civil institutions should be
improved.” Progress seems to depend on many concurrent favourable
conditions, far too complex to be followed out. But it has often been
remarked, that a cool climate from leading to industry and the various
arts has been highly favourable, or even indispensable for this end. The
Esquimaux, pressed by hard necessity, have succeeded in many ingenious
inventions, but their climate has been too severe for continued
progress. Nomadic habits, whether over wide plains, or through the dense
forests of the tropics, or along the shores of the sea, have in every
case been highly detrimental. Whilst observing the barbarous inhabitants
of Tierra del Fuego, it struck me that the possession of some property,
a fixed abode, and the union of many families under a chief, were the
indispensable requisites for civilisation. Such habits almost
necessitate the cultivation of the ground; and the first steps in
cultivation would probably result, as I have elsewhere shewn,[229] from
some such accident as the seeds of a fruit-tree falling on a heap of
refuse and producing an unusually fine variety. The problem, however, of
the first advance of savages towards civilisation is at present much too
difficult to be solved.

_Natural Selection as affecting Civilised Nations._—In the last and
present chapters I have considered the advancement of man from a former
semi-human condition to his present state as a barbarian. But some
remarks on the agency of natural selection on civilised nations may be
here worth adding. This subject has been ably discussed by Mr. W. R.
Greg,[230] and previously by Mr. Wallace and Mr. Galton.[231] Most of
my remarks are taken from these three authors. With savages, the weak in
body or mind are soon eliminated; and those that survive commonly
exhibit a vigorous state of health. We civilised men, on the other hand,
do our utmost to check the process of elimination; we build asylums for
the imbecile, the maimed, and the sick; we institute poor-laws; and our
medical men exert their utmost skill to save the life of every one to
the last moment. There is reason to believe that vaccination has
preserved thousands, who from a weak constitution would formerly have
succumbed to small-pox. Thus the weak members of civilised societies
propagate their kind. No one who has attended to the breeding of
domestic animals will doubt that this must be highly injurious to the
race of man. It is surprising how soon a want of care, or care wrongly
directed, leads to the degeneration of a domestic race; but excepting in
the case of man himself, hardly any one is so ignorant as to allow his
worst animals to breed.

The aid which we feel impelled to give to the helpless is mainly an
incidental result of the instinct of sympathy, which was originally
acquired as part of the social instincts, but subsequently rendered, in
the manner previously indicated, more tender and more widely diffused.
Nor could we check our sympathy, if so urged by hard reason, without
deterioration in the noblest part of our nature. The surgeon may harden
himself whilst performing an operation, for he knows that he is acting
for the good of his patient; but if we were intentionally to neglect the
weak and helpless, it could only be for a contingent benefit, with a
certain and great present evil. Hence we must bear without complaining
the undoubtedly bad effects of the weak surviving and propagating their
kind; but there appears to be at least one check in steady action,
namely the weaker and inferior members of society not marrying so freely
as the sound; and this check might be indefinitely increased, though
this is more to be hoped for than expected, by the weak in body or mind
refraining from marriage.

In all civilised countries man accumulates property and bequeaths it to
his children. So that the children in the same country do not by any
means start fair in the race for success. But this is far from an
unmixed evil; for without the accumulation of capital the arts could not
progress; and it is chiefly through their power that the civilised races
have extended, and are now everywhere extending, their range, so as to
take the place of the lower races. Nor does the moderate accumulation of
wealth interfere with the process of selection. When a poor man becomes
rich, his children enter trades or professions in which there is
struggle enough, so that the able in body and mind succeed best. The
presence of a body of well-instructed men, who have not to labour for
their daily bread, is important to a degree which cannot be
over-estimated; as all high intellectual work is carried on by them, and
on such work material progress of all kinds mainly depends, not to
mention other and higher advantages. No doubt wealth when very great
tends to convert men into useless drones, but their number is never
large; and some degree of elimination here occurs, as we daily see rich
men, who happen to be fools or profligate, squandering away all their

Primogeniture with entailed estates is a more direct evil, though it may
formerly have been a great advantage by the creation of a dominant
class, and any government is better than anarchy. The eldest sons,
though they may be weak in body or mind, generally marry, whilst the
younger sons, however superior in these respects, do not so generally
marry. Nor can worthless eldest sons with entailed estates squander
their wealth. But here, as elsewhere, the relations of civilised life
are so complex that some compensatory checks intervene. The men who are
rich through primogeniture are able to select generation after
generation the more beautiful and charming women; and these must
generally be healthy in body and active in mind. The evil consequences,
such as they may be, of the continued preservation of the same line of
descent, without any selection, are checked by men of rank always
wishing to increase their wealth and power; and this they effect by
marrying heiresses. But the daughters of parents who have produced
single children, are themselves, as Mr. Galton has shewn,[232] apt to be
sterile; and thus noble families are continually cut off in the direct
line, and their wealth flows into some side channel; but unfortunately
this channel is not determined by superiority of any kind.

Although civilisation thus checks in many ways the action of natural
selection, it apparently favours, by means of improved food and the
freedom from occasional hardships, the better development of the body.
This may be inferred from civilised men having been found, wherever
compared, to be physically stronger than savages. They appear also to
have equal powers of endurance, as has been proved in many adventurous
expeditions. Even the great luxury of the rich can be but little
detrimental; for the expectation of life of our aristocracy, at all ages
and of both sexes, is very little inferior to that of healthy English
lives in the lower classes.[233]

We will now look to the intellectual faculties alone. If in each grade
of society the members were divided into two equal bodies, the one
including the intellectually superior and the other the inferior, there
can be little doubt that the former would succeed best in all
occupations and rear a greater number of children. Even in the lowest
walks of life, skill and ability must be of some advantage, though in
many occupations, owing to the great division of labour, a very small
one. Hence in civilised nations there will be some tendency to an
increase both in the number and in the standard of the intellectually
able. But I do not wish to assert that this tendency may not be more
than counterbalanced in other ways, as by the multiplication of the
reckless and improvident; but even to such as these, ability must be
some advantage.

It has often been objected to views like the foregoing, that the most
eminent men who have ever lived have left no offspring to inherit their
great intellect. Mr. Galton says,[234] “I regret I am unable to solve
the simple question whether, and how far, men and women who are
prodigies of genius are infertile. I have, however, shewn that men of
eminence are by no means so.”

Great lawgivers, the founders of beneficent religions, great
philosophers and discoverers in science, aid the progress of mankind in
a far higher degree by their works than by leaving a numerous progeny.
In the case of corporeal structures, it is the selection of the slightly
better-endowed and the elimination of the slightly less well-endowed
individuals, and not the preservation of strongly-marked and rare
anomalies, that leads to the advancement of a species.[235] So it will
be with the intellectual faculties, namely from the somewhat more able
men in each grade of society succeeding rather better than the less
able, and consequently increasing in number, if not otherwise prevented.
When in any nation the standard of intellect and the number of
intellectual men have increased, we may expect from the law of the
deviation from an average, as shewn by Mr. Galton, that prodigies of
genius will appear somewhat more frequently than before.

In regard to the moral qualities, some elimination of the worst
dispositions is always in progress even in the most civilised nations.
Malefactors are executed, or imprisoned for long periods, so that they
cannot freely transmit their bad qualities. Melancholic and insane
persons are confined, or commit suicide. Violent and quarrelsome men
often come to a bloody end. Restless men who will not follow any steady
occupation—and this relic of barbarism is a great check to
civilisation[236]—emigrate to newly-settled countries, where they prove
useful pioneers. Intemperance is so highly destructive, that the
expectation of life of the intemperate, at the age, for instance, of
thirty, is only 13.8 years; whilst for the rural labourers of England at
the same age it is 40·59 years.[237] Profligate women bear few children,
and profligate men rarely marry; both suffer from disease. In the
breeding of domestic animals, the elimination of those individuals,
though few in number, which are in any marked manner inferior, is by no
means an unimportant element towards success. This especially holds good
with injurious characters which tend to reappear through reversion, such
as blackness in sheep; and with mankind some of the worst dispositions,
which occasionally without any assignable cause make their appearance in
families, may perhaps be reversions to a savage state, from which we are
not removed by very many generations. This view seems indeed recognised
in the common expression that such men are the black sheep of the

With civilised nations, as far as an advanced standard of morality, and
an increased number of fairly well-endowed men are concerned, natural
selection apparently effects but little; though the fundamental social
instincts were originally thus gained. But I have already said enough,
whilst treating of the lower races, on the causes which lead to the
advance of morality, namely, the approbation of our fellow-men—the
strengthening of our sympathies by habit—example and imitation—
reason—experience and even self-interest—instruction during
youth, and religious feelings.

A most important obstacle in civilised countries to an increase in the
number of men of a superior class has been strongly urged by Mr. Greg
and Mr. Galton,[238] namely, the fact that the very poor and reckless,
who are often degraded by vice, almost invariably marry early, whilst
the careful and frugal, who are generally otherwise virtuous, marry late
in life, so that they may be able to support themselves and their
children in comfort. Those who marry early produce within a given period
not only a greater number of generations, but, as shewn by Dr.
Duncan,[239] they produce many more children. The children, moreover,
that are born by mothers during the prime of life are heavier and
larger, and therefore probably more vigorous, than those born at other
periods. Thus the reckless, degraded, and often vicious members of
society, tend to increase at a quicker rate than the provident and
generally virtuous members. Or as Mr. Greg puts the case: “The careless,
squalid, unaspiring Irishman multiplies like rabbits: the frugal,
foreseeing, self-respecting, ambitious Scot, stern in his morality,
spiritual in his faith, sagacious and disciplined in his intelligence,
passes his best years in struggle and in celibacy, marries late, and
leaves few behind him. Given a land originally peopled by a thousand
Saxons and a thousand Celts—and in a dozen generations five-sixths of
the population would be Celts, but five-sixths of the property, of the
power, of the intellect, would belong to the one-sixth of Saxons that
remained. In the eternal ‘struggle for existence,’ it would be the
inferior and _less_ favoured race that had prevailed—and prevailed by
virtue not of its good qualities but of its faults.”

There are, however, some checks to this downward tendency. We have seen
that the intemperate suffer from a high rate of mortality, and the
extremely profligate leave few offspring. The poorest classes crowd into
towns, and it has been proved by Dr. Stark from the statistics of ten
years in Scotland,[240] that at all ages the death-rate is higher in
towns than in rural districts, “and during the first five years of life
the town death-rate is almost exactly double that of the rural
districts.” As these returns include both the rich and the poor, no
doubt more than double the number of births would be requisite to keep
up the number of the very poor inhabitants in the towns, relatively to
those in the country. With women, marriage at too early an age is highly
injurious; for it has been found in France that, “twice as many wives
under twenty die in the year, as died out of the same number of the
unmarried.” The mortality, also, of husbands under twenty is
“excessively high,”[241] but what the cause of this may be seems
doubtful. Lastly, if the men who prudently delay marrying until they can
bring up their families in comfort, were to select, as they often do,
women in the prime of life, the rate of increase in the better class
would be only slightly lessened.

It was established from an enormous body of statistics, taken during
1853, that the unmarried men throughout France, between the ages of
twenty and eighty, die in a much larger proportion than the married: for
instance, out of every 1000 unmarried men, between the ages of twenty
and thirty, 11·3 annually died, whilst of the married only 6·5
died.[242] A similar law was proved to hold good, during the years 1863
and 1864, with the entire population above the age of twenty in
Scotland: for instance, out of every 1000 unmarried men, between the
ages of twenty and thirty, 14·97 annually died, whilst of the married
only 7·24 died, that is less than half.[243] Dr. Stark remarks on this,
“Bachelorhood is more destructive to life than the most unwholesome
trades, or than residence in an unwholesome house or district where
there has never been the most distant attempt at sanitary improvement.”
He considers that the lessened mortality is the direct result of
“marriage, and the more regular domestic habits which attend that
state.” He admits, however, that the intemperate, profligate, and
criminal classes, whose duration of life is low, do not commonly marry;
and it must likewise be admitted that men with a weak constitution,
ill health, or any great infirmity in body or mind, will often not wish
to marry, or will be rejected. Dr. Stark seems to have come to the
conclusion that marriage in itself is a main cause of prolonged life,
from finding that aged married men still have a considerable advantage
in this respect over the unmarried of the same advanced age; but every
one must have known instances of men, who with weak health during youth
did not marry, and yet have survived to old age, though remaining weak
and therefore always with a lessened chance of life. There is another
remarkable circumstance which seems to support Dr. Stark’s conclusion,
namely, that widows and widowers in France suffer in comparison with the
married a very heavy rate of mortality; but Dr. Farr attributes this to
the poverty and evil habits consequent on the disruption of the family,
and to grief. On the whole we may conclude with Dr. Farr that the lesser
mortality of married than of unmarried men, which seems to be a general
law, “is mainly due to the constant elimination of imperfect types, and
to the skilful selection of the finest individuals out of each
successive generation;” the selection relating only to the marriage
state, and acting on all corporeal, intellectual, and moral qualities.
We may, therefore, infer that sound and good men who out of prudence
remain for a time unmarried do not suffer a high rate of mortality.

If the various checks specified in the two last paragraphs, and perhaps
others as yet unknown, do not prevent the reckless, the vicious and
otherwise inferior members of society from increasing at a quicker rate
than the better class of men, the nation will retrograde, as has
occurred too often in the history of the world. We must remember that
progress is no invariable rule. It is most difficult to say why one
civilised nation rises, becomes more powerful, and spreads more widely,
than another; or why the same nation progresses more at one time than at
another. We can only say that it depends on an increase in the actual
number of the population, on the number of the men endowed with high
intellectual and moral faculties, as well as on their standard of
excellence. Corporeal structure, except so far as vigour of body leads
to vigour of mind, appears to have little influence.

It has been urged by several writers that as high intellectual powers
are advantageous to a nation, the old Greeks, who stood some grades
higher in intellect than any race that has ever existed,[244] ought to
have risen, if the power of natural selection were real, still higher
in the scale, increased in number, and stocked the whole of Europe. Here
we have the tacit assumption, so often made with respect to corporeal
structures, that there is some innate tendency towards continued
development in mind and body. But development of all kinds depends on
many concurrent favourable circumstances. Natural selection acts only in
a tentative manner. Individuals and races may have acquired certain
indisputable advantages, and yet have perished from failing in other
characters. The Greeks may have retrograded from a want of coherence
between the many small states, from the small size of their whole
country, from the practice of slavery, or from extreme sensuality; for
they did not succumb until “they were enervated and corrupt to the very
core.”[245] The western nations of Europe, who now so immeasurably
surpass their former savage progenitors and stand at the summit of
civilisation, owe little or none of their superiority to direct
inheritance from the old Greeks; though they owe much to the written
works of this wonderful people.

Who can positively say why the Spanish nation, so dominant at one time,
has been distanced in the race. The awakening of the nations of Europe
from the dark ages is a still more perplexing problem. At this early
period, as Mr. Galton[246] has remarked, almost all the men of a gentle
nature, those given to meditation or culture of the mind, had no refuge
except in the bosom of the Church which demanded celibacy; and this
could hardly fail to have had a deteriorating influence on each
successive generation. During this same period the Holy Inquisition
selected with extreme care the freest and boldest men in order to burn
or imprison them. In Spain alone some of the best men—those who doubted
and questioned, and without doubting there can be no progress—were
eliminated during three centuries at the rate of a thousand a year. The
evil which the Catholic Church has thus effected, though no doubt
counterbalanced to a certain, perhaps large extent in other ways, is
incalculable; nevertheless, Europe has progressed at an unparalleled

The remarkable success of the English as colonists over other European
nations, which is well illustrated by comparing the progress of the
Canadians of English and French extraction, has been ascribed to their
“daring and persistent energy;” but who can say how the English gained
their energy. There is apparently much truth in the belief that the
wonderful progress of the United States, as well as the character of the
people, are the results of natural selection; the more energetic,
restless, and courageous men from all parts of Europe having emigrated
during the last ten or twelve generations to that great country, and
having there succeeded best.[247] Looking to the distant future, I do
not think that the Rev. Mr. Zincke takes an exaggerated view when he
says:[248] “All other series of events—as that which resulted in the
culture of mind in Greece, and that which resulted in the empire of
Rome—only appear to have purpose and value when viewed in connection
with, or rather as subsidiary to ... the great stream of Anglo-Saxon
emigration to the west.”

Obscure as is the problem of the advance of civilisation, we can at
least see that a nation which produced during a lengthened period the
greatest number of highly intellectual, energetic, brave, patriotic, and
benevolent men, would generally prevail over less favoured nations.

Natural selection follows from the struggle for existence; and this from
a rapid rate of increase. It is impossible not bitterly to regret, but
whether wisely is another question, the rate at which man tends to
increase; for this leads in barbarous tribes to infanticide and many
other evils, and in civilised nations to abject poverty, celibacy, and
to the late marriages of the prudent. But as man suffers from the same
physical evils with the lower animals, he has no right to expect an
immunity from the evils consequent on the struggle for existence. Had he
not been subjected to natural selection, assuredly he would never have
attained to the rank of manhood. When we see in many parts of the world
enormous areas of the most fertile land peopled by a few wandering
savages, but which are capable of supporting numerous happy homes, it
might be argued that the struggle for existence had not been
sufficiently severe to force man upwards to his highest standard.
Judging from all that we know of man and the lower animals, there has
always been sufficient variability in the intellectual and moral
faculties, for their steady advancement through natural selection. No
doubt such advancement demands many favourable concurrent circumstances;
but it may well be doubted whether the most favourable would have
sufficed, had not the rate of increase been rapid, and the consequent
struggle for existence severe to an extreme degree.

_On the evidence that all civilised nations were once barbarous._—As we
have had to consider the steps by which some semi-human creature has
been gradually raised to the rank of man in his most perfect state, the
present subject cannot be quite passed over. But it has been treated in
so full and admirable a manner by Sir J. Lubbock,[249] Mr. Tylor, Mr.
M’Lennan, and others, that I need here give only the briefest summary of
their results. The arguments recently advanced by the Duke of
Argyll[250] and formerly by Archbishop Whately, in favour of the belief
that man came into the world as a civilised being and that all savages
have since undergone degradation, seem to me weak in comparison with
those advanced on the other side. Many nations, no doubt, have fallen
away in civilisation, and some may have lapsed into utter barbarism,
though on this latter head I have not met with any evidence. The
Fuegians were probably compelled by other conquering hordes to settle in
their inhospitable country, and they may have become in consequence
somewhat more degraded; but it would be difficult to prove that they
have fallen much below the Botocudos who inhabit the finest parts of

The evidence that all civilised nations are the descendants of
barbarians, consists, on the one side, of clear traces of their former
low condition in still-existing customs, beliefs, language, &c.; and on
the other side, of proofs that savages are independently able to raise
themselves a few steps in the scale of civilisation, and have actually
thus risen. The evidence on the first head is extremely curious, but
cannot be here given: I refer to such cases as that, for instance, of
the art of enumeration, which, as Mr. Tylor clearly shews by the words
still used in some places, originated in counting the fingers, first of
one hand and then of the other, and lastly of the toes. We have traces
of this in our own decimal system, and in the Roman numerals, which
after reaching to the number V., change into VI., &c., when the other
hand no doubt was used. So again, “when we speak of three-score and ten,
we are counting by the vigesimal system, each score thus ideally made,
standing for 20—for ‘one man’ as a Mexican or Carib would put it.”[251]
According to a large and increasing school of philologists, every
language bears the marks of its slow and gradual evolution. So it is
with the art of writing, as letters are rudiments of pictorial
representations. It is hardly possible to read Mr. M’Lennan’s work[252]
and not admit that almost all civilised nations still retain some traces
of such rude habits as the forcible capture of wives. What ancient
nation, as the same author asks, can be named that was originally
monogamous? The primitive idea of justice, as shewn by the law of battle
and other customs of which traces still remain, was likewise most rude.
Many existing superstitions are the remnants of former false religious
beliefs. The highest form of religion—the grand idea of God hating sin
and loving righteousness—was unknown during primeval times.

Turning to the other kind of evidence: Sir J. Lubbock has shewn that
some savages have recently improved a little in some of their simpler
arts. From the extremely curious account which he gives of the weapons,
tools, and arts, used or practised by savages in various parts of the
world, it cannot be doubted that these have nearly all been independent
discoveries, excepting perhaps the art of making fire.[253] The
Australian boomerang is a good instance of one such independent
discovery. The Tahitians when first visited had advanced in many
respects beyond the inhabitants of most of the other Polynesian islands.
There are no just grounds for the belief that the high culture of the
native Peruvians and Mexicans was derived from any foreign source;[254]
many native plants were there cultivated, and a few native animals
domesticated. We should bear in mind that a wandering crew from some
semi-civilised land, if washed to the shores of America, would not,
judging from the small influence of most missionaries, have produced any
marked effect on the natives, unless they had already become somewhat
advanced. Looking to a very remote period in the history of the world,
we find, to use Sir J. Lubbock’s well-known terms, a paleolithic and
neolithic period; and no one will pretend that the art of grinding rough
flint tools was a borrowed one. In all parts of Europe, as far east as
Greece, in Palestine, India, Japan, New Zealand, and Africa, including
Egypt, flint tools have been discovered in abundance; and of their use
the existing inhabitants retain no tradition. There is also indirect
evidence of their former use by the Chinese and ancient Jews. Hence
there can hardly be a doubt that the inhabitants of these many
countries, which include nearly the whole civilised world, were once in
a barbarous condition. To believe that man was aboriginally civilised
and then suffered utter degradation in so many regions, is to take a
pitiably low view of human nature. It is apparently a truer and more
cheerful view that progress has been much more general than
retrogression; that man has risen, though by slow and interrupted steps,
from a lowly condition to the highest standard as yet attained by him in
knowledge, morals, and religion.



  Position of man in the animal series—The natural system
  genealogical—Adaptive characters of slight value—Various
  small points of resemblance between man and the
  Quadrumana—Rank of man in the natural system—Birthplace and
  antiquity of man—Absence of fossil connecting-links—Lower
  stages in the genealogy of man, as inferred, firstly from his
  affinities and secondly from his structure—Early androgynous
  condition of the Vertebrata—Conclusion.

Even if it be granted that the difference between man and his nearest
allies is as great in corporeal structure as some naturalists maintain,
and although we must grant that the difference between them is immense
in mental power, yet the facts given in the previous chapters declare,
as it appears to me, in the plainest manner, that man is descended from
some lower form, notwithstanding that connecting-links have not hitherto
been discovered.

Man is liable to numerous, slight, and diversified variations, which are
induced by the same general causes, are governed and transmitted in
accordance with the same general laws, as in the lower animals. Man
tends to multiply at so rapid a rate that his offspring are necessarily
exposed to a struggle for existence, and consequently to natural
selection. He has given rise to many races, some of which are so
different that they have often been ranked by naturalists as distinct
species. His body is constructed on the same homological plan as that of
other mammals, independently of the uses to which the several parts may
be put. He passes through the same phases of embryological development.
He retains many rudimentary and useless structures, which no doubt were
once serviceable. Characters occasionally make their reappearance in
him, which we have every reason to believe were possessed by his early
progenitors. If the origin of man had been wholly different from that of
all other animals, these various appearances would be mere empty
deceptions; but such an admission is incredible. These appearances, on
the other hand, are intelligible, at least to a large extent, if man is
the co-descendant with other mammals of some unknown and lower form.

Some naturalists, from being deeply impressed with the mental and
spiritual powers of man, have divided the whole organic world into three
kingdoms, the Human, the Animal, and the Vegetable, thus giving to man a
separate kingdom.[255] Spiritual powers cannot be compared or classed by
the naturalist; but he may endeavour to shew, as I have done, that the
mental faculties of man and the lower animals do not differ in kind,
although immensely in degree. A difference in degree, however great,
does not justify us in placing man in a distinct kingdom, as will
perhaps be best illustrated by comparing the mental powers of two
insects, namely, a coccus or scale-insect and an ant, which undoubtedly
belong to the same class. The difference is here greater, though of a
somewhat different kind, than that between man and the highest mammal.
The female coccus, whilst young, attaches itself by its proboscis to a
plant; sucks the sap but never moves again; is fertilised and lays eggs;
and this is its whole history. On the other hand, to describe the habits
and mental powers of a female ant, would require, as Pierre Huber has
shewn, a large volume; I may, however, briefly specify a few points.
Ants communicate information to each other, and several unite for the
same work, or games of play. They recognise their fellow-ants after
months of absence. They build great edifices, keep them clean, close the
doors in the evening, and post sentries. They make roads, and even
tunnels under rivers. They collect food for the community, and when an
object, too large for entrance, is brought to the nest, they enlarge the
door, and afterwards build it up again.[256] They go out to battle in
regular bands, and freely sacrifice their lives for the common weal.
They emigrate in accordance with a preconcerted plan. They capture
slaves. They keep Aphides as milch-cows. They move the eggs of their
aphides, as well as their own eggs and cocoons, into warm parts of the
nest, in order that they may be quickly hatched; and endless similar
facts could be given. On the whole, the difference in mental power
between an ant and a coccus is immense; yet no one has ever dreamed of
placing them in distinct classes, much less in distinct kingdoms. No
doubt this interval is bridged over by the intermediate mental powers of
many other insects; and this is not the case with man and the higher
apes. But we have every reason to believe that breaks in the series are
simply the result of many forms having become extinct.

Professor Owen, relying chiefly on the structure of the brain, has
divided the mammalian series into four sub-classes. One of these he
devotes to man; in another he places both the marsupials and the
monotremata; so that he makes man as distinct from all other mammals as
are these two latter groups conjoined. This view has not been accepted,
as far as I am aware, by any naturalist capable of forming an
independent judgment, and therefore need not here be further considered.

We can understand why a classification founded on any single character
or organ—even an organ so wonderfully complex and important as the
brain—or on the high development of the mental faculties, is almost
sure to prove unsatisfactory. This principle has indeed been tried with
hymenopterous insects; but when thus classed by their habits or
instincts, the arrangement proved thoroughly artificial.[257]
Classifications may, of course, be based on any character whatever, as
on size, colour, or the element inhabited; but naturalists have long
felt a profound conviction that there is a natural system. This system,
it is now generally admitted, must be, as far as possible, genealogical
in arrangement,—that is, the co-descendants of the same form must be
kept together in one group, separate from the co-descendants of any
other form; but if the parent-forms are related, so will be their
descendants, and the two groups together will form a larger group. The
amount of difference between the several groups—that is the amount of
modification which each has undergone—will be expressed by such terms
as genera, families, orders, and classes. As we have no record of the
lines of descent, these lines can be discovered only by observing the
degrees of resemblance between the beings which are to be classed. For
this object numerous points of resemblance are of much more importance
than the amount of similarity or dissimilarity in a few points. If two
languages were found to resemble each other in a multitude of words and
points of construction, they would be universally recognised as having
sprung from a common source, notwithstanding that they differed greatly
in some few words or points of construction. But with organic beings the
points of resemblance must not consist of adaptations to similar habits
of life: two animals may, for instance, have had their whole frames
modified for living in the water, and yet they will not be brought any
nearer to each other in the natural system. Hence we can see how it is
that resemblances in unimportant structures, in useless and rudimentary
organs, and in parts not as yet fully developed or functionally active,
are by far the most serviceable for classification; for they can hardly
be due to adaptations within a late period; and thus they reveal the old
lines of descent or of true affinity.

We can further see why a great amount of modification in some one
character ought not to lead us to separate widely any two organisms. A
part which already differs much from the same part in other allied forms
has already, according to the theory of evolution, varied much;
consequently it would (as long as the organism remained exposed to the
same exciting conditions) be liable to further variations of the same
kind; and these, if beneficial, would be preserved, and thus continually
augmented. In many cases the continued development of a part, for
instance, of the beak of a bird, or of the teeth of a mammal, would not
be advantageous to the species for gaining its food, or for any other
object; but with man we can see no definite limit, as far as advantage
is concerned, to the continued development of the brain and mental
faculties. Therefore in determining the position of man in the natural
or genealogical system, the extreme development of his brain ought not
to outweigh a multitude of resemblances in other less important or
quite unimportant points.

The greater number of naturalists who have taken into consideration the
whole structure of man, including his mental faculties, have followed
Blumenbach and Cuvier, and have placed man in a separate Order, under
the title of the Bimana, and therefore on an equality with the Orders of
the Quadrumana, Carnivora, &c. Recently many of our best naturalists
have recurred to the view first propounded by Linnæus, so remarkable for
his sagacity, and have placed man in the same Order with the Quadrumana,
under the title of the Primates. The justice of this conclusion will be
admitted if, in the first place, we bear in mind the remarks just made
on the comparatively small importance for classification of the great
development of the brain in man; bearing, also, in mind that the
strongly-marked differences between the skulls of man and the Quadrumana
(lately insisted upon by Bischoff, Aeby, and others) apparently follow
from their differently developed brains. In the second place, we must
remember that nearly all the other and more important differences
between man and the Quadrumana are manifestly adaptive in their nature,
and relate chiefly to the erect position of man; such as the structure
of his hand, foot, and pelvis, the curvature of his spine, and the
position of his head. The family of seals offers a good illustration of
the small importance of adaptive characters for classification. These
animals differ from all other Carnivora in the form of their bodies and
in the structure of their limbs, far more than does man from the higher
apes; yet in every system, from that of Cuvier to the most recent one by
Mr. Flower,[258] seals are ranked as a mere family in the Order of the
Carnivora. If man had not been his own classifier, he would never have
thought of founding a separate order for his own reception.

It would be beyond my limits, and quite beyond my knowledge, even to
name the innumerable points of structure in which man agrees with the
other Primates. Our great anatomist and philosopher, Prof. Huxley, has
fully discussed this subject,[259] and has come to the conclusion that
man in all parts of his organisation differs less from the higher apes,
than these do from the lower members of the same group. Consequently
there “is no justification for placing man in a distinct order.”

In an early part of this volume I brought forward various facts, shewing
how closely man agrees in constitution with the higher mammals; and this
agreement, no doubt, depends on our close similarity in minute structure
and chemical composition. I gave, as instances, our liability to the
same diseases, and to the attacks of allied parasites; our tastes in
common for the same stimulants, and the similar effects thus produced,
as well as by various drugs; and other such facts.

As small unimportant points of resemblance between man and the higher
apes are not commonly noticed in systematic works, and as, when
numerous, they clearly reveal our relationship, I will specify a few
such points. The relative position of the features are manifestly the
same in man and the Quadrumana; and the various emotions are displayed
by nearly similar movements of the muscles and skin, chiefly above the
eyebrows and round the mouth. Some few expressions are, indeed, almost
the same, as in the weeping of certain kinds of monkeys, and in the
laughing noise made by others, during which the corners of the mouth are
drawn backwards, and the lower eyelids wrinkled. The external ears are
curiously alike. In man the nose is much more prominent than in most
monkeys; but we may trace the commencement of an aquiline curvature in
the nose of the Hoolock Gibbon; and this in the _Semnopithecus nasica_
is carried to a ridiculous extreme.

The faces of many monkeys are ornamented with beards, whiskers, or
moustaches. The hair on the head grows to a great length in some species
of Semnopithecus;[260] and in the Bonnet monkey (_Macacus radiatus_) it
radiates from a point on the crown, with a parting down the middle, as
in man. It is commonly said that the forehead gives to man his noble and
intellectual appearance; but the thick hair on the head of the Bonnet
monkey terminates abruptly downwards, and is succeeded by such short and
fine hair, or down, that at a little distance the forehead, with the
exception of the eyebrows, appears quite naked. It has been erroneously
asserted that eyebrows are not present in any monkey. In the species
just named the degree of nakedness of the forehead differs in different
individuals; and Eschricht states[261] that in our children the limit
between the hairy scalp and the naked forehead is sometimes not well
defined; so that here we seem to have a trifling case of reversion to a
progenitor, in whom the forehead had not as yet become quite naked.

It is well known that the hair on our arms tends to converge from above
and below to a point at the elbow. This curious arrangement, so unlike
that in most of the lower mammals, is common to the gorilla, chimpanzee,
orang, some species of Hylobates, and even to some few American monkeys.
But in _Hylobates agilis_ the hair on the fore-arm is directed
downwards or towards the wrist in the ordinary manner; and in _H. lar_
it is nearly erect, with only a very slight forward inclination; so that
in this latter species it is in a transitional state. It can hardly be
doubted that with most mammals the thickness of the hair and its
direction on the back is adapted to throw off the rain; even the
transverse hairs on the fore-legs of a dog may serve for this end when
he is coiled up asleep. Mr. Wallace remarks that the convergence of the
hair towards the elbow on the arms of the orang (whose habits he has so
carefully studied) serves to throw off the rain, when, as is the custom
of this animal, the arms are bent, with the hands clasped round a branch
or over its own head. We should, however, bear in mind that the attitude
of an animal may perhaps be in part determined by the direction of the
hair; and not the direction of the hair by the attitude. If the above
explanation is correct in the case of the orang, the hair on our
fore-arms offers a curious record of our former state; for no one
supposes that it is now of any use in throwing off the rain, nor in our
present erect condition is it properly directed for this purpose.

It would, however, be rash to trust too much to the principle of
adaptation in regard to the direction of the hair in man or his early
progenitors; for it is impossible to study the figures given by
Eschricht of the arrangement of the hair on the human fœtus (this
being the same as in the adult) and not agree with this excellent
observer that other and more complex causes have intervened. The points
of convergence seem to stand in some relation to those points in the
embryo which are last closed in during development. There appears, also,
to exist some relation between the arrangement of the hair on the
limbs, and the course of the medullary arteries.[262]

It must not be supposed that the resemblances between man and certain
apes in the above and many other points—such as in having a naked
forehead, long tresses on the head, &c.—are all necessarily the result
of unbroken inheritance from a common progenitor thus characterised, or
of subsequent reversion. Many of these resemblances are more probably
due to analogous variation, which follows, as I have elsewhere attempted
to shew,[263] from co-descended organisms having a similar constitution
and having been acted on by similar causes inducing variability. With
respect to the similar direction of the hair on the fore-arms of man and
certain monkeys, as this character is common to almost all the
anthropomorphous apes, it may probably be attributed to inheritance; but
not certainly so, as some very distinct American monkeys are thus
characterised. The same remark is applicable to the tailless condition
of man; for the tail is absent in all the anthropomorphous apes.
Nevertheless this character cannot with certainty be attributed to
inheritance, as the tail, though not absent, is rudimentary in several
other Old World and in some New World species, and is quite absent in
several species belonging to the allied group of Lemurs.

Although, as we have now seen, man has no just right to form a separate
Order for his own reception, he may perhaps claim a distinct Sub-order
or Family. Prof. Huxley, in his last work,[264] divides the Primates
into three Sub-orders; namely, the Anthropidæ with man alone, the
Simiadæ including monkeys of all kinds, and the Lemuridæ with the
diversified genera of lemurs. As far as differences in certain important
points of structure are concerned, man may no doubt rightly claim the
rank of a Sub-order; and this rank is too low, if we look chiefly to his
mental faculties. Nevertheless, under a genealogical point of view it
appears that this rank is too high, and that man ought to form merely a
Family, or possibly even only a Sub-family. If we imagine three lines of
descent proceeding from a common source, it is quite conceivable that
two of them might after the lapse of ages be so slightly changed as
still to remain as species of the same genus; whilst the third line
might become so greatly modified as to deserve to rank as a distinct
Sub-family, Family, or even Order. But in this case it is almost certain
that the third line would still retain through inheritance numerous
small points of resemblance with the other two lines. Here then would
occur the difficulty, at present insoluble, how much weight we ought to
assign in our classifications to strongly-marked differences in some few
points,—that is to the amount of modification undergone; and how much
to close resemblance in numerous unimportant points, as indicating the
lines of descent or genealogy. The former alternative is the most
obvious, and perhaps the safest, though the latter appears the most
correct as giving a truly natural classification.

To form a judgment on this head, with reference to man we must glance at
the classification of the Simiadæ. This family is divided by almost all
naturalists into the Catarhine group, or Old World monkeys, all of which
are characterised (as their name expresses) by the peculiar structure of
their nostrils and by having four premolars in each jaw; and into the
Platyrhine group or New World monkeys (including two very distinct
sub-groups), all of which are characterised by differently-constructed
nostrils and by having six premolars in each jaw. Some other small
differences might be mentioned. Now man unquestionably belongs in his
dentition, in the structure of his nostrils, and some other respects, to
the Catarhine or Old World division; nor does he resemble the
Platyrhines more closely than the Catarhines in any characters,
excepting in a few of not much importance and apparently of an adaptive
nature. Therefore it would be against all probability to suppose that
some ancient New World species had varied, and had thus produced a
man-like creature with all the distinctive characters proper to the Old
World division; losing at the same time all its own distinctive
characters. There can consequently hardly be a doubt that man is an
offshoot from the Old World Simian stem; and that under a genealogical
point of view, he must be classed with the Catarhine division.[265]

The anthropomorphous apes, namely the gorilla, chimpanzee, orang, and
hylobates, are separated as a distinct sub-group from the other Old
World monkeys by most naturalists. I am aware that Gratiolet, relying on
the structure of the brain, does not admit the existence of this
sub-group, and no doubt it is a broken one; thus the orang, as Mr. St.
G. Mivart remarks,[266] “is one of the most peculiar and aberrant forms
to be found in the Order.” The remaining, non-anthropomorphous, Old
World monkeys, are again divided by some naturalists into two or three
smaller sub-groups; the genus Semnopithecus, with its peculiar
sacculated stomach, being the type of one such sub-group. But it appears
from M. Gaudry’s wonderful discoveries in Attica, that during the
Miocene period a form existed there, which connected Semnopithecus and
Macacus; and this probably illustrates the manner in which the other and
higher groups were once blended together.

If the anthropomorphous apes be admitted to form a natural sub-group,
then as man agrees with them, not only in all those characters which he
possesses in common with the whole Catarhine group, but in other
peculiar characters, such as the absence of a tail and of callosities
and in general appearance, we may infer that some ancient member of the
anthropomorphous sub-group gave birth to man. It is not probable that a
member of one of the other lower sub-groups should, through the law of
analogous variation, have given rise to a man-like creature, resembling
the higher anthropomorphous apes in so many respects. No doubt man, in
comparison with most of his allies, has undergone an extraordinary
amount of modification, chiefly in consequence of his greatly developed
brain and erect position; nevertheless we should bear in mind that he
“is but one of several exceptional forms of Primates.”[267]

Every naturalist, who believes in the principle of evolution, will
grant that the two main divisions of the Simiadæ, namely the Catarhine
and Platyrhine monkeys, with their sub-groups, have all proceeded from
some one extremely ancient progenitor. The early descendants of this
progenitor, before they had diverged to any considerable extent from
each other, would still have formed a single natural group; but some of
the species or incipient genera would have already begun to indicate by
their diverging characters the future distinctive marks of the Catarhine
and Platyrhine divisions. Hence the members of this supposed ancient
group would not have been so uniform in their dentition or in the
structure of their nostrils, as are the existing Catarhine monkeys in
one way and the Platyrhines in another way, but would have resembled in
this respect the allied Lemuridæ which differ greatly from each other in
the form of their muzzles,[268] and to an extraordinary degree in their

The Catarhine and Platyrhine monkeys agree in a multitude of characters,
as is shewn by their unquestionably belonging to one and the same Order.
The many characters which they possess in common can hardly have been
independently acquired by so many distinct species; so that these
characters must have been inherited. But an ancient form which possessed
many characters common to the Catarhine and Platyrhine monkeys, and
others in an intermediate condition, and some few perhaps distinct from
those now present in either group, would undoubtedly have been ranked,
if seen by a naturalist, as an ape or monkey. And as man under a
genealogical point of view belongs to the Catarhine or Old World stock,
we must conclude, however much the conclusion may revolt our pride,
that our early progenitors would have been properly thus
designated.[269] But we must not fall into the error of supposing that
the early progenitor of the whole Simian stock, including man, was
identical with, or even closely resembled, any existing ape or monkey.

_On the Birthplace and Antiquity of Man._—We are naturally led to
enquire where was the birthplace of man at that stage of descent when
our progenitors diverged from the Catarhine stock. The fact that they
belonged to this stock clearly shews that they inhabited the Old World;
but not Australia nor any oceanic island, as we may infer from the laws
of geographical distribution. In each great region of the world the
living mammals are closely related to the extinct species of the same
region. It is therefore probable that Africa was formerly inhabited by
extinct apes closely allied to the gorilla and chimpanzee; and as these
two species are now man’s nearest allies, it is somewhat more probable
that our early progenitors lived on the African continent than
elsewhere. But it is useless to speculate on this subject, for an ape
nearly as large as a man, namely the Dryopithecus of Lartet, which was
closely allied to the anthropomorphous Hylobates, existed in Europe
during the Upper Miocene period; and since so remote a period the earth
has certainly undergone many great revolutions, and there has been ample
time for migration on the largest scale.

At the period and place, whenever and wherever it may have been, when
man first lost his hairy covering, he probably inhabited a hot country;
and this would have been favourable for a frugiferous diet, on which,
judging from analogy, he subsisted. We are far from knowing how long ago
it was when man first diverged from the Catarhine stock; but this may
have occurred at an epoch as remote as the Eocene period; for the higher
apes had diverged from the lower apes as early as the Upper Miocene
period, as shewn by the existence of the Dryopithecus. We are also quite
ignorant at how rapid a rate organisms, whether high or low in the
scale, may under favourable circumstances be modified: we know, however,
that some have retained the same form during an enormous lapse of time.
From what we see going on under domestication, we learn that within the
same period some of the co-descendants of the same species may be not at
all changed, some a little, and some greatly changed. Thus it may have
been with man, who has undergone a great amount of modification in
certain characters in comparison with the higher apes.

The great break in the organic chain between man and his nearest allies,
which cannot be bridged over by any extinct or living species, has often
been advanced as a grave objection to the belief that man is descended
from some lower form; but this objection will not appear of much weight
to those who, convinced by general reasons, believe in the general
principle of evolution. Breaks incessantly occur in all parts of the
series, some being wide, sharp and defined, others less so in various
degrees; as between the orang and its nearest allies—between the
Tarsius and the other Lemuridæ—between the elephant and in a more
striking manner between the Ornithorhynchus or Echidna, and other
mammals. But all these breaks depend merely on the number of related
forms which have become extinct. At some future period, not very distant
as measured by centuries, the civilised races of man will almost
certainly exterminate and replace throughout the world the savage races.
At the same time the anthropomorphous apes, as Professor Schaaffhausen
has remarked,[270] will no doubt be exterminated. The break will then be
rendered wider, for it will intervene between man in a more civilised
state, as we may hope, than the Caucasian, and some ape as low as a
baboon, instead of as at present between the negro or Australian and the

With respect to the absence of fossil remains, serving to connect man
with his ape-like progenitors, no one will lay much stress on this fact,
who will read Sir C. Lyell’s discussion,[271] in which he shews that in
all the vertebrate classes the discovery of fossil remains has been an
extremely slow and fortuitous process. Nor should it be forgotten that
those regions which are the most likely to afford remains connecting man
with some extinct ape-like creature, have not as yet been searched by

_Lower Stages in the Genealogy of Man._—We have seen that man appears
to have diverged from the Catarhine or Old World division of the
Simiadæ, after these had diverged from the New World division. We will
now endeavour to follow the more remote traces of his genealogy,
trusting in the first place to the mutual affinities between the various
classes and orders, with some slight aid from the periods, as far as
ascertained, of their successive appearance on the earth. The Lemuridæ
stand below and close to the Simiadæ, constituting a very distinct
family of the Primates, or, according to Häckel, a distinct Order. This
group is diversified and broken to an extraordinary degree, and includes
many aberrant forms. It has, therefore, probably suffered much
extinction. Most of the remnants survive on islands, namely in
Madagascar and in the islands of the Malayan archipelago, where they
have not been exposed to such severe competition as they would have been
on well-stocked continents. This group likewise presents many
gradations, leading, as Huxley remarks,[272] “insensibly from the crown
and summit of the animal creation down to creatures from which there is
but a step, as it seems, to the lowest, smallest, and least intelligent
of the placental mammalia.” From these various considerations it is
probable that the Simiadæ were originally developed from the progenitors
of the existing Lemuridæ; and these in their turn from forms standing
very low in the mammalian series.

The Marsupials stand in many important characters below the placental
mammals. They appeared at an earlier geological period, and their range
was formerly much more extensive than what it now is. Hence the
Placentata are generally supposed to have been derived from the
Implacentata or Marsupials; not, however, from forms closely like the
existing Marsupials, but from their early progenitors. The Monotremata
are plainly allied to the Marsupials; forming a third and still lower
division in the great mammalian series. They are represented at the
present day solely by the Ornithorhynchus and Echidna; and these two
forms may be safely considered as relics of a much larger group which
have been preserved in Australia through some favourable concurrence of
circumstances. The Monotremata are eminently interesting, as in several
important points of structure they lead towards the class of reptiles.

In attempting to trace the genealogy of the Mammalia, and therefore of
man, lower down in the series, we become involved in greater and greater
obscurity. He who wishes to see what ingenuity and knowledge can effect,
may consult Prof. Häckel’s works.[273] I will content myself with a few
general remarks. Every evolutionist will admit that the five great
vertebrate classes, namely, mammals, birds, reptiles, amphibians, and
fishes, are all descended from some one prototype; for they have much in
common, especially during their embryonic state. As the class of fishes
is the most lowly organised and appeared before the others, we may
conclude that all the members of the vertebrate kingdom are derived from
some fish-like animal, less highly organised than any as yet found in
the lowest known formations. The belief that animals so distinct as a
monkey or elephant and a humming-bird, a snake, frog, and fish, &c.,
could all have sprung from the same parents, will appear monstrous to
those who have not attended to the recent progress of natural history.
For this belief implies the former existence of links closely binding
together all these forms, now so utterly unlike.

Nevertheless it is certain that groups of animals have existed, or do
now exist, which serve to connect more or less closely the several great
vertebrate classes. We have seen that the Ornithorhynchus graduates
towards reptiles; and Prof. Huxley has made the remarkable discovery,
confirmed by Mr. Cope and others, that the old Dinosaurians are
intermediate in many important respects between certain reptiles and
certain birds—the latter consisting of the ostrich-tribe (itself
evidently a widely-diffused remnant of a larger group) and of the
Archeopteryx, that strange Secondary bird having a long tail like that
of the lizard. Again, according to Prof. Owen,[274] the
Ichthyosaurians—great sea-lizards furnished with paddles—present many
affinities with fishes, or rather, according to Huxley, with amphibians.
This latter class (including in its highest division frogs and toads) is
plainly allied to the Ganoid fishes. These latter fishes swarmed during
the earlier geological periods, and were constructed on what is called a
highly generalised type, that is they presented diversified affinities
with other groups of organisms. The amphibians and fishes are also so
closely united by the Lepidosiren, that naturalists long disputed in
which of these two classes it ought to be placed. The Lepidosiren and
some few Ganoid fishes have been preserved from utter extinction by
inhabiting our rivers, which are harbours of refuge, bearing the same
relation to the great waters of the ocean that islands bear to

Lastly, one single member of the immense and diversified class of
fishes, namely the lancelet or amphioxus, is so different from all other
fishes, that Häckel maintains that it ought to form a distinct class in
the vertebrate kingdom. This fish is remarkable for its negative
characters; it can hardly be said to possess a brain, vertebral column,
or heart, &c.; so that it was classed by the older naturalists amongst
the worms. Many years ago Prof. Goodsir perceived that the lancelet
presented some affinities with the Ascidians, which are invertebrate,
hermaphrodite, marine creatures permanently attached to a support. They
hardly appear like animals, and consist of a simple, tough, leathery
sack, with two small projecting orifices. They belong to the Molluscoida
of Huxley—a lower division of the great kingdom of the Mollusca; but
they have recently been placed by some naturalists amongst the Vermes or
worms. Their larvæ somewhat resemble tadpoles in shape,[275] and have
the power of swimming freely about. Some observations lately made by M.
Kowalevsky,[276] since confirmed by Prof. Kuppfer, will form a discovery
of extraordinary interest, if still further extended, as I hear from M.
Kowalevsky in Naples he has now effected. The discovery is that the
larvæ of Ascidians are related to the Vertebrata, in their manner of
development, in the relative position of the nervous system, and in
possessing a structure closely like the _chorda dorsalis_ of vertebrate
animals. It thus appears, if we may rely on embryology, which has always
proved the safest guide in classification, that we have at last gained a
clue to the source whence the Vertebrata have been derived. We should
thus be justified in believing that at an extremely remote period a
group of animals existed, resembling in many respects the larvæ of our
present Ascidians, which diverged into two great branches—the one
retrograding in development and producing the present class of
Ascidians, the other rising to the crown and summit of the animal
kingdom by giving birth to the Vertebrata.

We have thus far endeavoured rudely to trace the genealogy of the
Vertebrata by the aid of their mutual affinities. We will now look to
man as he exists; and we shall, I think, be able partially to restore
during successive periods, but not in due order of time, the structure
of our early progenitors. This can be effected by means of the rudiments
which man still retains, by the characters which occasionally make their
appearance in him through reversion, and by the aid of the principles of
morphology and embryology. The various facts, to which I shall here
allude, have been given in the previous chapters. The early progenitors
of man were no doubt once covered with hair, both sexes having beards;
their ears were pointed and capable of movement; and their bodies were
provided with a tail, having the proper muscles. Their limbs and bodies
were also acted on by many muscles which now only occasionally reappear,
but are normally present in the Quadrumana. The great artery and nerve
of the humerus ran through a supra-condyloid foramen. At this or some
earlier period, the intestine gave forth a much larger diverticulum or
cæcum than that now existing. The foot, judging from the condition of
the great toe in the fœtus, was then prehensile; and our progenitors,
no doubt, were arboreal in their habits, frequenting some warm,
forest-clad land. The males were provided with great canine teeth,
which served them as formidable weapons.

At a much earlier period the uterus was double; the excreta were voided
through a cloaca; and the eye was protected by a third eyelid or
nictitating membrane. At a still earlier period the progenitors of man
must have been aquatic in their habits; for morphology plainly tells us
that our lungs consist of a modified swim-bladder, which once served as
a float. The clefts on the neck in the embryo of man show where the
branchiæ once existed. At about this period the true kidneys were
replaced by the corpora Wolffiana. The heart existed as a simple
pulsating vessel; and the chorda dorsalis took the place of a vertebral
column. These early predecessors of man, thus seen in the dim recesses
of time, must have been as lowly organised as the lancelet or amphioxus,
or even still more lowly organised.

There is one other point deserving a fuller notice. It has long been
known that in the vertebrate kingdom one sex bears rudiments of various
accessory parts, appertaining to the reproductive system, which properly
belong to the opposite sex; and it has now been ascertained that at a
very early embryonic period both sexes possess true male and female
glands. Hence some extremely remote progenitor of the whole vertebrate
kingdom appears to have been hermaphrodite or androgynous.[277] But here
we encounter a singular difficulty. In the mammalian class the males
possess in their vesiculæ prostaticæ rudiments of a uterus with the
adjacent passage; they bear also rudiments of mammæ, and some male
marsupials have rudiments of a marsupial sack.[278] Other analogous
facts could be added. Are we, then, to suppose that some extremely
ancient mammal possessed organs proper to both sexes, that is, continued
androgynous after it had acquired the chief distinctions of its proper
class, and therefore after it had diverged from the lower classes of the
vertebrate kingdom? This seems improbable in the highest degree; for had
this been the case, we might have expected that some few members of the
two lower classes, namely fishes[279] and amphibians, would still have
remained androgynous. We must, on the contrary, believe that when the
five vertebrate classes diverged from their common progenitor the sexes
had already become separated. To account, however, for male mammals
possessing rudiments of the accessory female organs, and for female
mammals possessing rudiments of the masculine organs, we need not
suppose that their early progenitors were still androgynous after they
had assumed their chief mammalian characters. It is quite possible that
as the one sex gradually acquired the accessory organs proper to it,
some of the successive steps or modifications were transmitted to the
opposite sex. When we treat of sexual selection, we shall meet with
innumerable instances of this form of transmission,—as in the case of
the spurs, plumes, and brilliant colours, acquired by male birds for
battle or ornament, and transferred to the females in an imperfect or
rudimentary condition.

The possession by male mammals of functionally imperfect mammary organs
is, in some respects, especially curious. The Monotremata have the
proper milk-secreting glands with orifices, but no nipples; and as these
animals stand at the very base of the mammalian series, it is probable
that the progenitors of the class possessed, in like manner, the
milk-secreting glands, but no nipples. This conclusion is supported by
what is known of their manner of development; for Professor Turner
informs me, on the authority of Kölliker and Lauger, that in the embryo
the mammary glands can be distinctly traced before the nipples are in
the least visible; and it should be borne in mind that the development
of successive parts in the individual generally seems to represent and
accord with the development of successive beings in the same line of
descent. The Marsupials differ from the Monotremata by possessing
nipples; so that these organs were probably first acquired by the
Marsupials after they had diverged from, and risen above, the
Monotremata, and were then transmitted to the placental mammals. No one
will suppose that after the Marsupials had approximately acquired their
present structure, and therefore at a rather late period in the
development of the mammalian series, any of its members still remained
androgynous. We seem, therefore, compelled to recur to the foregoing
view, and to conclude that the nipples were first developed in the
females of some very early marsupial form, and were then, in accordance
with a common law of inheritance, transferred in a functionally
imperfect condition to the males.

Nevertheless a suspicion has sometimes crossed my mind that long after
the progenitors of the whole mammalian class had ceased to be
androgynous, both sexes might have yielded milk and thus nourished their
young; and in the case of the Marsupials, that both sexes might have
carried their young in marsupial sacks. This will not appear utterly
incredible, if we reflect that the males of syngnathous fishes receive
the eggs of the females in their abdominal pouches, hatch them, and
afterwards, as some believe, nourish the young;[280]—that certain other
male fishes hatch the eggs within their mouths or branchial
cavities;—that certain male toads take the chaplets of eggs from the
females and wind them round their own thighs, keeping them there until
the tadpoles are born;—that certain male birds undertake the whole duty
of incubation, and that male pigeons, as well as the females, feed their
nestlings with a secretion from their crops. But the above suspicion
first occurred to me from the mammary glands in male mammals being
developed so much more perfectly than the rudiments of those other
accessory reproductive parts, which are found in the one sex though
proper to the other. The mammary glands and nipples, as they exist in
male mammals, can indeed hardly be called rudimentary; they are simply
not fully developed and not functionally active. They are
sympathetically affected under the influence of certain diseases, like
the same organs in the female. At birth they often secrete a few drops
of milk; and they have been known occasionally in man and other mammals
to become well developed, and to yield a fair supply of milk. Now if we
suppose that during a former prolonged period male mammals aided the
females in nursing their offspring, and that afterwards from some cause,
as from a smaller number of young being produced, the males ceased
giving this aid, disuse of the organs during maturity would lead to
their becoming inactive; and from two well-known principles of
inheritance this state of inactivity would probably be transmitted to
the males at the corresponding age of maturity. But at all earlier ages
these organs would be left unaffected, so that they would be equally
well developed in the young of both sexes.

_Conclusion._—The best definition of advancement or progress in the
organic scale ever given, is that by Von Baer; and this rests on the
amount of differentiation and specialisation of the several parts of the
same being, when arrived, as I should be inclined to add, at maturity.
Now as organisms have become slowly adapted by means of natural
selection for diversified lines of life, their parts will have become,
from the advantage gained by the division of physiological labour, more
and more differentiated and specialised for various functions. The same
part appears often to have been modified first for one purpose, and then
long afterwards for some other and quite distinct purpose; and thus all
the parts are rendered more and more complex. But each organism will
still retain the general type of structure of the progenitor from which
it was aboriginally derived. In accordance with this view it seems, if
we turn to geological evidence, that organisation on the whole has
advanced throughout the world by slow and interrupted steps. In the
great kingdom of the Vertebrata it has culminated in man. It must not,
however, be supposed that groups of organic beings are always supplanted
and disappear as soon as they have given birth to other and more perfect
groups. The latter, though victorious over their predecessors, may not
have become better adapted for all places in the economy of nature. Some
old forms appear to have survived from inhabiting protected sites, where
they have not been exposed to very severe competition; and these often
aid us in constructing our genealogies, by giving us a fair idea of
former and lost populations. But we must not fall into the error of
looking at the existing members of any lowly-organised group as perfect
representatives of their ancient predecessors.

The most ancient progenitors in the kingdom of the Vertebrata, at which
we are able to obtain an obscure glance, apparently consisted of a group
of marine animals,[281] resembling the larvæ of existing Ascidians.
These animals probably gave rise to a group of fishes, as lowly
organised as the lancelet; and from these the Ganoids, and other fishes
like the Lepidosiren, must have been developed. From such fish a very
small advance would carry us on to the amphibians. We have seen that
birds and reptiles were once intimately connected together; and the
Monotremata now, in a slight degree, connect mammals with reptiles. But
no one can at present say by what line of descent the three higher and
related classes, namely, mammals, birds, and reptiles, were derived from
either of the two lower vertebrate classes, namely amphibians and
fishes. In the class of mammals the steps are not difficult to conceive
which led from the ancient Monotremata to the ancient Marsupials; and
from these to the early progenitors of the placental mammals. We may
thus ascend to the Lemuridæ; and the interval is not wide from these to
the Simiadæ. The Simiadæ then branched off into two great stems, the New
World and Old World monkeys; and from the latter, at a remote period,
Man, the wonder and glory of the Universe, proceeded.

Thus we have given to man a pedigree of prodigious length, but not, it
may be said, of noble quality. The world, it has often been remarked,
appears as if it had long been preparing for the advent of man; and
this, in one sense is strictly true, for he owes his birth to a long
line of progenitors. If any single link in this chain had never existed,
man would not have been exactly what he now is. Unless we wilfully close
our eyes, we may, with our present knowledge, approximately recognise
our parentage; nor need we feel ashamed of it. The most humble organism
is something much higher than the inorganic dust under our feet; and no
one with an unbiassed mind can study any living creature, however
humble, without being struck with enthusiasm at its marvellous structure
and properties.



  The nature and value of specific characters—Application to the
  races of man—Arguments in favour of, and opposed to, ranking
  the so-called races of man as distinct
  species—Sub-species—Monogenists and polygenists—Convergence
  of character—Numerous points of resemblance in body and mind
  between the most distinct races of man—The state of man when
  he first spread over the earth—Each race not descended from a
  single pair—The extinction of races—The formation of
  races—The effects of crossing—Slight influence of the direct
  action of the conditions of life—Slight or no influence of
  natural selection—Sexual selection.

It is not my intention here to describe the several so-called races of
men; but to inquire what is the value of the differences between them
under a classificatory point of view, and how they have originated. In
determining whether two or more allied forms ought to be ranked as
species or varieties, naturalists are practically guided by the
following considerations; namely, the amount of difference between them,
and whether such differences relate to few or many points of structure,
and whether they are of physiological importance; but more especially
whether they are constant. Constancy of character is what is chiefly
valued and sought for by naturalists. Whenever it can be shewn, or
rendered probable, that the forms in question have remained distinct for
a long period, this becomes an argument of much weight in favour of
treating them as species. Even a slight degree of sterility between any
two forms when first crossed, or in their offspring, is generally
considered as a decisive test of their specific distinctness; and their
continued persistence without blending within the same area, is usually
accepted as sufficient evidence, either of some degree of mutual
sterility, or in the case of animals of some repugnance to mutual

Independently of blending from intercrossing, the complete absence, in a
well-investigated region, of varieties linking together any two
closely-allied forms, is probably the most important of all the
criterions of their specific distinctness; and this is a somewhat
different consideration from mere constancy of character, for two forms
may be highly variable and yet not yield intermediate varieties.
Geographical distribution is often unconsciously and sometimes
consciously brought into play; so that forms living in two widely
separated areas, in which most of the other inhabitants are specifically
distinct, are themselves usually looked at as distinct; but in truth
this affords no aid in distinguishing geographical races from so-called
good or true species.

Now let us apply these generally-admitted principles to the races of
man, viewing him in the same spirit as a naturalist would any other
animal. In regard to the amount of difference between the races, we must
make some allowance for our nice powers of discrimination gained by the
long habit of observing ourselves. In India, as Elphinstone
remarks,[282] although a newly-arrived European cannot at first
distinguish the various native races, yet they soon appear to him
extremely dissimilar; and the Hindoo cannot at first perceive any
difference between the several European nations. Even the most distinct
races of man, with the exception of certain negro tribes, are much more
like each other in form than would at first be supposed. This is well
shewn by the French photographs in the Collection Anthropologique du
Muséum of the men belonging to various races, the greater number of
which, as many persons to whom I have shown them have remarked, might
pass for Europeans. Nevertheless, these men if seen alive would
undoubtedly appear very distinct, so that we are clearly much influenced
in our judgment by the mere colour of the skin and hair, by slight
differences in the features, and by expression.

There is, however, no doubt that the various races, when carefully
compared and measured, differ much from each other,—as in the texture
of the hair, the relative proportions of all parts of the body,[283] the
capacity of the lungs, the form and capacity of the skull, and even in
the convolutions of the brain.[284] But it would be an endless task to
specify the numerous points of structural difference. The races differ
also in constitution, in acclimatisation, and in liability to certain
diseases. Their mental characteristics are likewise very distinct;
chiefly as it would appear in their emotional, but partly in their
intellectual, faculties. Every one who has had the opportunity of
comparison, must have been struck with the contrast between the
taciturn, even morose, aborigines of S. America and the light-hearted,
talkative negroes. There is a nearly similar contrast between the Malays
and the Papuans,[285] who live under the same physical conditions, and
are separated from each other only by a narrow space of sea.

We will first consider the arguments which may be advanced in favour of
classing the races of man as distinct species, and then those on the
other side. If a naturalist, who had never before seen such beings, were
to compare a Negro, Hottentot, Australian, or Mongolian, he would at
once perceive that they differed in a multitude of characters, some of
slight and some of considerable importance. On inquiry he would find
that they were adapted to live under widely different climates, and that
they differed somewhat in bodily constitution and mental disposition. If
he were then told that hundreds of similar specimens could be brought
from the same countries, he would assuredly declare that they were as
good species as many to which he had been in the habit of affixing
specific names. This conclusion would be greatly strengthened as soon as
he had ascertained that these forms had all retained the same character
for many centuries; and that negroes, apparently identical with existing
negroes, had lived at least 4000 years ago.[286] He would also hear from
an excellent observer, Dr. Lund,[287] that the human skulls found in
the caves of Brazil, entombed with many extinct mammals, belonged to the
same type as that now prevailing throughout the American Continent.

Our naturalist would then perhaps turn to geographical distribution, and
he would probably declare that forms differing not only in appearance,
but fitted for the hottest and dampest or driest countries, as well as
for the arctic regions, must be distinct species. He might appeal to the
fact that no one species in the group next to man, namely the
Quadrumana, can resist a low temperature or any considerable change of
climate; and that those species which come nearest to man have never
been reared to maturity, even under the temperate climate of Europe. He
would be deeply impressed with the fact, first noticed by Agassiz,[288]
that the different races of man are distributed over the world in the
same zoological provinces, as those inhabited by undoubtedly distinct
species and genera of mammals. This is manifestly the case with the
Australian, Mongolian, and Negro races of man; in a less well-marked
manner with the Hottentots; but plainly with the Papuans and Malays, who
are separated, as Mr. Wallace has shewn, by nearly the same line which
divides the great Malayan and Australian zoological provinces. The
aborigines of America range throughout the Continent; and this at first
appears opposed to the above rule, for most of the productions of the
Southern and Northern halves differ widely; yet some few living forms,
as the opossum, range from the one into the other, as did formerly some
of the gigantic Edentata. The Esquimaux, like other Arctic animals,
extend round the whole polar regions. It should be observed that the
mammalian forms which inhabit the several zoological provinces, do not
differ from each other in the same degree; so that it can hardly be
considered as an anomaly that the Negro differs more, and the American
much less, from the other races of man than do the mammals of the same
continents from those of the other provinces. Man, it may be added, does
not appear to have aboriginally inhabited any oceanic island; and in
this respect he resembles the other members of his class.

In determining whether the varieties of the same kind of domestic animal
should be ranked as specifically distinct, that is, whether any of them
are descended from distinct wild species, every naturalist would lay
much stress on the fact, if established, of their external parasites
being specifically distinct. All the more stress would be laid on this
fact, as it would be an exceptional one, for I am informed by Mr. Denny
that the most different kinds of dogs, fowls, and pigeons, in England,
are infested by the same species of Pediculi or lice. Now Mr. A. Murray
has carefully examined the Pediculi collected in different countries
from the different races of man;[289] and he finds that they differ, not
only in colour, but in the structure of their claws and limbs. In every
case in which numerous specimens were obtained the differences were
constant. The surgeon of a whaling ship in the Pacific assured me that
when the Pediculi, with which some Sandwich Islanders on board swarmed,
strayed on to the bodies of the English sailors, they died in the course
of three or four days. These Pediculi were darker coloured and appeared
different from those proper to the natives of Chiloe in South America,
of which he gave me specimens. These, again, appeared larger and much
softer than European lice. Mr. Murray procured four kinds from Africa,
namely from the Negroes of the Eastern and Western coasts, from the
Hottentots and Caffres; two kinds from the natives of Australia; two
from North, and two from South America. In these latter cases it may be
presumed that the Pediculi came from natives inhabiting different
districts. With insects slight structural differences, if constant, are
generally esteemed of specific value: and the fact of the races of man
being infested by parasites, which appear to be specifically distinct,
might fairly be urged as an argument that the races themselves ought to
be classed as distinct species.

Our supposed naturalist having proceeded thus far in his investigation,
would next inquire whether the races of men, when crossed, were in any
degree sterile. He might consult the work[290] of a cautious and
philosophical observer, Professor Broca; and in this he would find good,
evidence that some races were quite fertile together; but evidence of an
opposite nature in regard to other races. Thus it has been asserted that
the native women of Australia and Tasmania rarely produce children to
European men; the evidence, however, on this head has now been shewn to
be almost valueless. The half-castes are killed by the pure blacks; and
an account has lately been published of eleven half-caste youths
murdered and burnt at the same time, whose remains were found by the
police.[291] Again, it has often been said that when mulattoes
intermarry they produce few children; on the other hand, Dr. Bachman of
Charlestown[292] positively asserts that he has known mulatto families
which have intermarried for several generations, and have continued on
an average as fertile as either pure whites or pure blacks. Inquiries
formerly made by Sir C. Lyell on this subject led him, as he informs me,
to the same conclusion. In the United States the census for the year
1854 included, according to Dr. Bachman, 405,751 mulattoes; and this
number, considering all the circumstances of the case, seems small; but
it may partly be accounted for by the degraded and anomalous position of
the class, and by the profligacy of the women. A certain amount of
absorption of mulattoes into negroes must always be in progress; and
this would lead to an apparent diminution of the former. The inferior
vitality of mulattoes is spoken of in a trustworthy work[293] as a
well-known phenomenon; but this is a different consideration from their
lessened fertility; and can hardly be advanced as a proof of the
specific distinctness of the parent races. No doubt both animal and
vegetable hybrids, when produced from extremely distinct species, are
liable to premature death; but the parents of mulattoes cannot be put
under the category of extremely distinct species. The common Mule, so
notorious for long life and vigour, and yet so sterile, shews how little
necessary connection there is in hybrids between lessened fertility and
vitality: other analogous cases could be added.

Even if it should hereafter be proved that all the races of men were
perfectly fertile together, he who was inclined from other reasons to
rank them as distinct species, might with justice argue that fertility
and sterility are not safe criterions of specific distinctness. We know
that these qualities are easily affected by changed conditions of life
or by close inter-breeding, and that they are governed by highly complex
laws, for instance that of the unequal fertility of reciprocal crosses
between the same two species. With forms which must be ranked as
undoubted species, a perfect series exists from those which are
absolutely sterile when crossed, to those which are almost or quite
fertile. The degrees of sterility do not coincide strictly with the
degrees of difference in external structure or habits of life. Man in
many respects may be compared with those animals which have long been
domesticated, and a large body of evidence can be advanced in favour of
the Pallasian doctrine[294] that domestication tends to eliminate the
sterility which is so general a result of the crossing of species in a
state of nature. From these several considerations, it may be justly
urged that the perfect fertility of the intercrossed races of man, if
established, would not absolutely preclude us from ranking them as
distinct species.

Independently of fertility, the character of the offspring from a cross
has sometimes been thought to afford evidence whether the parent-forms
ought to be ranked as species or varieties; but after carefully studying
the evidence, I have come to the conclusion that no general rules of
this kind can be trusted. Thus with mankind the offspring of distinct
races resemble in all respects the offspring of true species and of
varieties. This is shewn, for instance, by the manner in which the
characters of both parents are blended, and by one form absorbing
another through repeated crosses. In this latter case the progeny both
of crossed species and varieties retain for a long period a tendency to
revert to their ancestors, especially to that one which is prepotent in
transmission. When any character has suddenly appeared in a race or
species as the result of a single act of variation, as is general with
monstrosities,[295] and this race is crossed with another not thus
characterised, the characters in question do not commonly appear in a
blended condition in the young, but are transmitted to them either
perfectly developed or not at all. As with the crossed races of man
cases of this kind rarely or never occur, this may be used as an
argument against the view suggested by some ethnologists, namely that
certain characters, for instance the blackness of the negro, first
appeared as a sudden variation or sport. Had this occurred, it is
probable that mulattoes would often have been born, either completely
black or completely white.

We have now seen that a naturalist might feel himself fully justified in
ranking the races of man as distinct species; for he has found that they
are distinguished by many differences in structure and constitution,
some being of importance. These differences have, also, remained nearly
constant for very long periods of time. He will have been in some degree
influenced by the enormous range of man, which is a great anomaly in the
class of mammals, if mankind be viewed as a single species. He will have
been struck with the distribution of the several so-called races, in
accordance with that of other undoubtedly distinct species of mammals.
Finally he might urge that the mutual fertility of all the races has not
as yet been fully proved; and even if proved would not be an absolute
proof of their specific identity.

On the other side of the question, if our supposed naturalist were to
enquire whether the forms of man kept distinct like ordinary species,
when mingled together in large numbers in the same country, he would
immediately discover that this was by no means the case. In Brazil he
would behold an immense mongrel population of Negroes and Portuguese; in
Chiloe and other parts of South America, he would behold the whole
population consisting of Indians and Spaniards blended in various
degrees.[296] In many parts of the same continent he would meet with the
most complex crosses between Negroes, Indians, and Europeans; and such
triple crosses afford the severest test, judging from the vegetable
kingdom, of the mutual fertility of the parent-forms. In one island of
the Pacific he would find a small population of mingled Polynesian and
English blood; and in the Viti Archipelago a population of Polynesians
and Negritos crossed in all degrees. Many analogous cases could be
added, for instance, in South Africa. Hence the races of man are not
sufficiently distinct to co-exist without fusion; and this it is, which
in all ordinary cases affords the usual test of specific distinctness.

Our naturalist would likewise be much disturbed as soon as he perceived
that the distinctive characters of every race of man were highly
variable. This strikes every one when he first beholds the negro-slaves
in Brazil, who have been imported from all parts of Africa. The same
remark holds good with the Polynesians, and with many other races. It
may be doubted whether any character can be named which is distinctive
of a race and is constant. Savages, even within the limits of the same
tribe, are not nearly so uniform in character, as has often been said.
Hottentot women offer certain peculiarities, more strongly marked than
those occurring in any other race, but these are known not to be of
constant occurrence. In the several American tribes, colour and
hairyness differ considerably; as does colour to a certain degree, and
the shape of the features greatly, in the Negroes of Africa. The shape
of the skull varies much in some races;[297] and so it is with every
other character. Now all naturalists have learnt by dearly-bought
experience, how rash it is to attempt to define species by the aid of
inconstant characters.

But the most weighty of all the arguments against treating the races of
man as distinct species, is that they graduate into each other,
independently in many cases, as far as we can judge, of their having
intercrossed. Man has been studied more carefully than any other organic
being, and yet there is the greatest possible diversity amongst capable
judges whether he should be classed as a single species or race, or as
two (Virey), as three (Jacquinot), as four (Kant), five (Blumenbach),
six (Buffon), seven (Hunter), eight (Agassiz), eleven (Pickering),
fifteen (Bory St. Vincent), sixteen (Desmoulins), twenty-two (Morton),
sixty (Crawfurd), or as sixty-three, according to Burke.[298] This
diversity of judgment does not prove that the races ought not to be
ranked as species, but it shews that they graduate into each other, and
that it is hardly possible to discover clear distinctive characters
between them.

Every naturalist who has had the misfortune to undertake the
description of a group of highly varying organisms, has encountered
cases (I speak after experience) precisely like that of man; and if of a
cautious disposition, he will end by uniting all the forms which
graduate into each other as a single species; for he will say to himself
that he has no right to give names to objects which he cannot define.
Cases of this kind occur in the Order which includes man, namely in
certain genera of monkeys; whilst in other genera, as in Cercopithecus,
most of the species can be determined with certainty. In the American
genus Cebus, the various forms are ranked by some naturalists as
species, by others as mere geographical races. Now if numerous specimens
of Cebus were collected from all parts of South America, and those forms
which at present appear to be specifically distinct, were found to
graduate into each other by close steps, they would be ranked by most
naturalists as mere varieties or races; and thus the greater number of
naturalists have acted with respect to the races of man. Nevertheless it
must be confessed that there are forms, at least in the vegetable
kingdom,[299] which we cannot avoid naming as species, but which are
connected together, independently of intercrossing, by numberless

Some naturalists have lately employed the term “sub-species” to
designate forms which possess many of the characteristics of true
species, but which hardly deserve so high a rank. Now if we reflect on
the weighty arguments, above given, for raising the races of man to the
dignity of species, and the insuperable difficulties on the other side
in defining them, the term “sub-species” might here be used with much
propriety. But from long habit the term “race” will perhaps always be
employed. The choice of terms is only so far important as it is highly
desirable to use, as far as that may be possible, the same terms for the
same degrees of difference. Unfortunately this is rarely possible; for
within the same family the larger genera generally include
closely-allied forms, which can be distinguished only with much
difficulty, whilst the smaller genera include forms that are perfectly
distinct; yet all must equally be ranked as species. So again the
species within the same large genus by no means resemble each other to
the same degree: on the contrary, in most cases some of them can be
arranged in little groups round other species, like satellites round

The question whether mankind consists of one or several species has of
late years been much agitated by anthropologists, who are divided into
two schools of monogenists and polygenists. Those who do not admit the
principle of evolution, must look at species either as separate
creations or as in some manner distinct entities; and they must decide
what forms to rank as species by the analogy of other organic beings
which are commonly thus received. But it is a hopeless endeavour to
decide this point on sound grounds, until some definition of the term
“species” is generally accepted; and the definition must not include an
element which cannot possibly be ascertained, such as an act of
creation. We might as well attempt without any definition to decide
whether a certain number of houses should be called a village, or town,
or city. We have a practical illustration of the difficulty in the
never-ending doubts whether many closely-allied mammals, birds,
insects, and plants, which represent each other in North America and
Europe, should be ranked species or geographical races; and so it is
with the productions of many islands situated at some little distance
from the nearest continent.

Those naturalists, on the other hand, who admit the principle of
evolution, and this is now admitted by the greater number of rising men,
will feel no doubt that all the races of man are descended from a single
primitive stock; whether or not they think fit to designate them as
distinct species, for the sake of expressing their amount of
difference.[301] With our domestic animals the question whether the
various races have arisen from one or more species is different.
Although all such races, as well as all the natural species within the
same genus, have undoubtedly sprung from the same primitive stock, yet
it is a fit subject for discussion, whether, for instance, all the
domestic races of the dog have acquired their present differences since
some one species was first domesticated and bred by man; or whether they
owe some of their characters to inheritance from distinct species, which
had already been modified in a state of nature. With mankind no such
question can arise, for he cannot be said to have been domesticated at
any particular period.

When the races of man diverged at an extremely remote epoch from their
common progenitor, they will have differed but little from each other,
and been few in number; consequently they will then, as far as their
distinguishing characters are concerned, have had less claim to rank as
distinct species, than the existing so-called races. Nevertheless such
early races would perhaps have been ranked by some naturalists as
distinct species, so arbitrary is the term, if their differences,
although extremely slight, had been more constant than at present, and
had not graduated into each other.

It is, however, possible, though far from probable, that the early
progenitors of man might at first have diverged much in character, until
they became more unlike each other than are any existing races; but that
subsequently, as suggested by Vogt,[302] they converged in character.
When man selects for the same object the offspring of two distinct
species, he sometimes induces, as far as general appearance is
concerned, a considerable amount of convergence. This is the case, as
shewn by Von Nathusius,[303] with the improved breeds of pigs, which are
descended from two distinct species; and in a less well-marked manner
with the improved breeds of cattle. A great anatomist, Gratiolet,
maintains that the anthropomorphous apes do not form a natural
sub-group; but that the orang is a highly developed gibbon or
semnopithecus; the chimpanzee a highly developed macacus; and the
gorilla a highly developed mandrill. If this conclusion, which rests
almost exclusively on brain-characters, be admitted, we should have a
case of convergence at least in external characters, for the
anthropomorphous apes are certainly more like each other in many points
than they are to other apes. All analogical resemblances, as of a whale
to a fish, may indeed be said to be cases of convergence; but this term
has never been applied to superficial and adaptive resemblances. It
would be extremely rash in most cases to attribute to convergence close
similarity in many points of structure in beings which had once been
widely different. The form of a crystal is determined solely by the
molecular forces, and it is not surprising that dissimilar substances
should sometimes assume the same form; but with organic beings we should
bear in mind that the form of each depends on an infinitude of complex
relations, namely on the variations which have arisen, these being due
to causes far too intricate to be followed out,—on the nature of the
variations which have been preserved, and this depends on the
surrounding physical conditions, and in a still higher degree on the
surrounding organisms with which each has come into competition,—and
lastly, on inheritance (in itself a fluctuating element) from
innumerable progenitors, all of which have had their forms determined
through equally complex relations. It appears utterly incredible that
two organisms, if differing in a marked manner, should ever afterwards
converge so closely as to lead to a near approach to identity throughout
their whole organisation. In the case of the convergent pigs above
referred to, evidence of their descent from two primitive stocks is
still plainly retained, according to Von Nathusius, in certain bones of
their skulls. If the races of man were descended, as supposed by some
naturalists, from two or more distinct species, which had differed as
much, or nearly as much, from each other, as the orang differs from the
gorilla, it can hardly be doubted that marked differences in the
structure of certain bones would still have been discoverable in man as
he now exists.

Although the existing races of man differ in many respects, as in
colour, hair, shape of skull, proportions of the body, &c., yet if their
whole organisation be taken into consideration they are found to
resemble each other closely in a multitude of points. Many of these
points are of so unimportant or of so singular a nature, that it is
extremely improbable that they should have been independently acquired
by aboriginally distinct species or races. The same remark holds good
with equal or greater force with respect to the numerous points of
mental similarity between the most distinct races of man. The American
aborigines, Negroes and Europeans differ as much from each other in mind
as any three races that can be named; yet I was incessantly struck,
whilst living with the Fuegians on board the “Beagle,” with the many
little traits of character, shewing how similar their minds were to
ours; and so it was with a full-blooded negro with whom I happened once
to be intimate.

He who will carefully read Mr. Tylor’s and Sir J. Lubbock’s interesting
works[304] can hardly fail to be deeply impressed with the close
similarity between the men of all races in tastes, dispositions and
habits. This is shewn by the pleasure which they all take in dancing,
rude music, acting, painting, tattooing, and otherwise decorating
themselves,—in their mutual comprehension of gesture-language—and, as
I shall be able to shew in a future essay, by the same expression in
their features, and by the same inarticulate cries, when they are
excited by various emotions. This similarity, or rather identity, is
striking, when contrasted with the different expressions which may be
observed in distinct species of monkeys. There is good evidence that the
art of shooting with bows and arrows has not been handed down from any
common progenitor of mankind, yet the stone arrow-heads, brought from
the most distant parts of the world and manufactured at the most remote
periods, are, as Nilsson has shewn,[305] almost identical; and this fact
can only be accounted for by the various races having similar inventive
or mental powers. The same observation has been made by
archæologists[306] with respect to certain widely-prevalent ornaments,
such as zigzags, &c.; and with respect to various simple beliefs and
customs, such as the burying of the dead under megalithic structures. I
remember observing in South America,[307] that there, as in so many
other parts of the world, man has generally chosen the summits of lofty
hills, on which to throw up piles of stones, either for the sake of
recording some remarkable event, or for burying his dead.

Now when naturalists observe a close agreement in numerous small details
of habits, tastes and dispositions between two or more domestic races,
or between nearly-allied natural forms, they use this fact as an
argument that all are descended from a common progenitor who was thus
endowed; and consequently that all should be classed under the same
species. The same argument may be applied with much force to the races
of man.

As it is improbable that the numerous and unimportant points of
resemblance between the several races of man in bodily structure and
mental faculties (I do not here refer to similar customs) should all
have been independently acquired, they must have been inherited from
progenitors who were thus characterised. We thus gain some insight into
the early state of man, before he had spread step by step over the face
of the earth. The spreading of man to regions widely separated by the
sea, no doubt, preceded any considerable amount of divergence of
character in the several races; for otherwise we should sometimes meet
with the same race in distinct continents; and this is never the case.
Sir J. Lubbock, after comparing the arts now practised by savages in all
parts of the world, specifies those which man could not have known, when
he first wandered from his original birthplace; for if once learnt they
would never have been forgotten.[308] He thus shews that “the spear,
which is but a development of the knife-point, and the club, which is
but a long hammer, are the only things left.” He admits, however, that
the art of making fire probably had already been discovered, for it is
common to all the races now existing, and was known to the ancient
cave-inhabitants of Europe. Perhaps the art of making rude canoes or
rafts was likewise known; but as man existed at a remote epoch, when the
land in many places stood at a very different level, he would have been
able, without the aid of canoes, to have spread widely. Sir J. Lubbock
further remarks how improbable it is that our earliest ancestors could
have “counted as high as ten, considering that so many races now in
existence cannot get beyond four.” Nevertheless, at this early period,
the intellectual and social faculties of man could hardly have been
inferior in any extreme degree to those now possessed by the lowest
savages; otherwise primeval man could not have been so eminently
successful in the struggle for life, as proved by his early and wide

From the fundamental differences between certain languages, some
philologists have inferred that when man first became widely diffused he
was not a speaking animal; but it may be suspected that languages, far
less perfect than any now spoken, aided by gestures, might have been
used, and yet have left no traces on subsequent and more
highly-developed tongues. Without the use of some language, however
imperfect, it appears doubtful whether man’s intellect could have risen
to the standard implied by his dominant position at an early period.

Whether primeval man, when he possessed very few arts of the rudest
kind, and when his power of language was extremely imperfect, would have
deserved to be called man, must depend on the definition which we
employ. In a series of forms graduating insensibly from some ape-like
creature to man as he now exists, it would be impossible to fix on any
definite point when the term “man” ought to be used. But this is a
matter of very little importance. So again it is almost a matter of
indifference whether the so-called races of man are thus designated, or
are ranked as species or sub-species; but the latter term appears the
most appropriate. Finally, we may conclude that when the principles of
evolution are generally accepted, as they surely will be before long,
the dispute between the monogenists and the polygenists will die a
silent and unobserved death.

One other question ought not to be passed over without notice, namely,
whether, as is sometimes assumed, each sub-species or race of man has
sprung from a single pair of progenitors. With our domestic animals a
new race can readily be formed from a single pair possessing some new
character, or even from a single individual thus characterised, by
carefully matching the varying offspring; but most of our races have
been formed, not intentionally from a selected pair, but unconsciously
by the preservation of many individuals which have varied, however
slightly, in some useful or desired manner. If in one country stronger
and heavier horses, and in another country lighter and fleeter horses,
were habitually preferred, we may feel sure that two distinct sub-breeds
would, in the course of time, be produced, without any particular pairs
or individuals having been separated and bred from in either country.
Many races have been thus formed, and their manner of formation is
closely analogous with that of natural species. We know, also, that the
horses which have been brought to the Falkland Islands have become,
during successive generations, smaller and weaker, whilst those which
have run wild on the Pampas have acquired larger and coarser heads; and
such changes are manifestly due, not to any one pair, but to all the
individuals having been subjected to the same conditions, aided,
perhaps, by the principle of reversion. The new sub-breeds in none of
these cases are descended from any single pair, but from many
individuals which have varied in different degrees, but in the same
general manner; and we may conclude that the races of man have been
similarly produced, the modifications being either the direct result of
exposure to different conditions, or the indirect result of some form of
selection. But to this latter subject we shall presently return.

_On the Extinction of the Races of Man._—The partial and complete
extinction of many races and sub-races of man are historically known
events. Humboldt saw in South America a parrot which was the sole living
creature that could speak the language of a lost tribe. Ancient
monuments and stone implements found in all parts of the world, of which
no tradition is preserved by the present inhabitants, indicate much
extinction. Some small and broken tribes, remnants of former races,
still survive in isolated and generally mountainous districts. In Europe
the ancient races were all, according to Schaaffhausen,[309] “lower in
the scale than the rudest living savages;” they must therefore have
differed, to a certain extent, from any existing race. The remains
described by Professor Broca[310] from Les Eyzies, though they
unfortunately appear to have belonged to a single family, indicate a
race with a most singular combination of low or simious and high
characteristics, and is “entirely different from any other race, ancient
or modern, that we have ever heard of.” It differed, therefore, from the
quaternary race of the caverns of Belgium.

Unfavourable physical conditions appear to have had but little effect in
the extinction of races.[311] Man has long lived in the extreme regions
of the North, with no wood wherewith to make his canoes or other
implements, and with blubber alone for burning and giving him warmth,
but more especially for melting the snow. In the Southern extremity of
America the Fuegians survive without the protection of clothes, or of
any building worthy to be called a hovel. In South Africa the aborigines
wander over the most arid plains, where dangerous beasts abound. Man can
withstand the deadly influence of the Terai at the foot of the Himalaya,
and the pestilential shores of tropical Africa.

Extinction follows chiefly from the competition of tribe with tribe,
and race with race. Various checks are always in action, as specified in
a former chapter, which serve to keep down the numbers of each savage
tribe,—such as periodical famines, the wandering of the parents and the
consequent deaths of infants, prolonged suckling, the stealing of women,
wars, accidents, sickness, licentiousness, especially infanticide, and,
perhaps, lessened fertility from less nutritious food, and many
hardships. If from any cause any one of these checks is lessened, even
in a slight degree, the tribe thus favoured will tend to increase; and
when one of two adjoining tribes becomes more numerous and powerful than
the other, the contest is soon settled by war, slaughter, cannibalism,
slavery, and absorption. Even when a weaker tribe is not thus abruptly
swept away, if it once begins to decrease, it generally goes on
decreasing until it is extinct.[312]

When civilised nations come into contact with barbarians the struggle is
short, except where a deadly climate gives its aid to the native race.
Of the causes which lead to the victory of civilised nations, some are
plain and some very obscure. We can see that the cultivation of the land
will be fatal in many ways to savages, for they cannot, or will not,
change their habits. New diseases and vices are highly destructive; and
it appears that in every nation a new disease causes much death, until
those who are most susceptible to its destructive influence are
gradually weeded out;[313] and so it may be with the evil effects from
spirituous liquors, as well as with the unconquerably strong taste for
them shewn by so many savages. It further appears, mysterious as is the
fact, that the first meeting of distinct and separated people generates
disease.[314] Mr. Sproat, who in Vancouver Island closely attended to
the subject of extinction, believes that changed habits of life, which
always follow from the advent of Europeans, induces much ill-health. He
lays, also, great stress on so trifling a cause as that the natives
become “bewildered and dull by the new life around them; they lose the
motives for exertion, and get no new ones in their place.”[315]

The grade of civilisation seems a most important element in the success
of nations which come in competition. A few centuries ago Europe feared
the inroads of Eastern barbarians; now, any such fear would be
ridiculous. It is a more curious fact, that savages did not formerly
waste away, as Mr. Bagehot has remarked, before the classical nations,
as they now do before modern civilised nations; had they done so, the
old moralists would have mused over the event; but there is no lament in
any writer of that period over the perishing barbarians.[316]

Although the gradual decrease and final extinction of the races of man
is an obscure problem, we can see that it depends on many causes,
differing in different places and at different times. It is the same
difficult problem as that presented by the extinction of one of the
higher animals—of the fossil horse, for instance, which disappeared
from South America, soon afterwards to be replaced, within the same
districts, by countless troops of the Spanish horse. The New Zealander
seems conscious of this parallelism, for he compares his future fate
with that of the native rat almost exterminated by the European rat. The
difficulty, though great to our imagination, and really great if we wish
to ascertain the precise causes, ought not to be so to our reason, as
long as we keep steadily in mind that the increase of each species and
each race is constantly hindered by various checks; so that if any new
check, or cause of destruction, even a slight one, be superadded, the
race will surely decrease in number; and as it has everywhere been
observed that savages are much opposed to any change of habits, by which
means injurious checks could be counterbalanced, decreasing numbers will
sooner or later lead to extinction; the end, in most cases, being
promptly determined by the inroads of increasing and conquering tribes.

_On the Formation of the Races of Man._—It may be premised that when we
find the same race, though broken up into distinct tribes, ranging over
a great area, as over America, we may attribute their general
resemblance to descent from a common stock. In some cases the crossing
of races already, distinct has led to the formation of new races. The
singular fact that Europeans and Hindoos, who belong to the same Aryan
stock and speak a language fundamentally the same, differ widely in
appearance, whilst Europeans differ but little from Jews, who belong to
the Semitic stock and speak quite another language, has been accounted
for by Broca[317] through the Aryan branches having been largely crossed
during their wide diffusion by various indigenous tribes. When two races
in close contact cross, the first result is a heterogeneous mixture:
thus Mr. Hunter, in describing the Santali or hill-tribes of India, says
that hundreds of imperceptible gradations may be traced “from the black,
squat tribes of the mountains to the tall olive-coloured Brahman, with
his intellectual brow, calm eyes, and high but narrow head;” so that it
is necessary in courts of justice to ask the witnesses whether they are
Santalis or Hindoos.[318] Whether a heterogeneous people, such as the
inhabitants of some of the Polynesian islands, formed by the crossing of
two distinct races, with few or no pure members left, would ever become
homogeneous, is not known from direct evidence. But as with our
domesticated animals, a crossed breed can certainly, in the course of a
few generations, be fixed and made uniform by careful selection,[319] we
may infer that the free and prolonged intercrossing during many
generations of a heterogeneous mixture would supply the place of
selection, and overcome any tendency to reversion, so that a crossed
race would ultimately become homogeneous, though it might not partake in
an equal degree of the characters of the two parent-races.

Of all the differences between the races of man, the colour of the skin
is the most conspicuous and one of the best marked. Differences of this
kind, it was formerly thought, could be accounted for by long exposure
under different climates; but Pallas first shewed that this view is not
tenable, and he has been followed by almost all anthropologists.[320]
The view has been rejected chiefly because the distribution of the
variously coloured races, most of whom must have long inhabited their
present homes, does not coincide with corresponding differences of
climate. Weight must also be given to such cases as that of the Dutch
families, who, as we hear on excellent authority,[321] have not
undergone the least change of colour, after residing for three centuries
in South Africa. The uniform appearance in various parts of the world of
gypsies and Jews, though the uniformity of the latter has been somewhat
exaggerated,[322] is likewise an argument on the same side. A very damp
or a very dry atmosphere has been supposed to be more influential in
modifying the colour of the skin than mere heat; but as D’Orbigny in
South America, and Livingstone in Africa, arrived at diametrically
opposite conclusions with respect to dampness and dryness, any
conclusion on this head must be considered as very doubtful.[323]

Various facts, which I have elsewhere given, prove that the colour of
the skin and hair is sometimes correlated in a surprising manner with a
complete immunity from the action of certain vegetable poisons and from
the attacks of certain parasites. Hence it occurred to me, that negroes
and other dark races might have acquired their dark tints by the darker
individuals escaping during a long series of generations from the deadly
influence of the miasmas of their native countries.

I afterwards found that the same idea had long ago occurred to Dr.
Wells.[324] That negroes, and even mulattoes, are almost completely
exempt from the yellow-fever, which is so destructive in tropical
America, has long been known.[325] They likewise escape to a large
extent the fatal intermittent fevers that prevail along, at least, 2600
miles of the shores of Africa, and which annually cause one-fifth of the
white settlers to die, and another fifth to return home invalided.[326]
This immunity in the negro seems to be partly inherent, depending on
some unknown peculiarity of constitution, and partly the result of
acclimatisation. Pouchet[327] states that the negro regiments, borrowed
from the Viceroy of Egypt for the Mexican war, which had been recruited
near the Soudan, escaped the yellow-fever almost equally well with the
negroes originally brought from various parts of Africa, and accustomed
to the climate of the West Indies. That acclimatisation plays a part is
shewn by the many cases in which negroes, after having resided for some
time in a colder climate, have become to a certain extent liable to
tropical fevers.[328] The nature of the climate under which the white
races have long resided, likewise has some influence on them; for during
the fearful epidemic of yellow-fever in Demerara during 1837, Dr. Blair
found that the death-rate of the immigrants was proportional to the
latitude of the country whence they had come. With the negro the
immunity, as far as it is the result of acclimatisation, implies
exposure during a prodigious length of time; for the aborigines of
tropical America, who have resided there from time immemorial, are not
exempt from yellow-fever; and the Rev. B. Tristram states, that there
are districts in Northern Africa which the native inhabitants are
compelled annually to leave, though the negroes can remain with safety.

That the immunity of the negro is in any degree correlated with the
colour of his skin is a mere conjecture: it may be correlated with some
difference in his blood, nervous system, or other tissues. Nevertheless,
from the facts above alluded to, and from some connection apparently
existing between complexion and a tendency to consumption, the
conjecture seemed to me not improbable. Consequently I endeavoured, with
but little success,[329] to ascertain how far it held good. The late
Dr. Daniell, who had long lived on the West Coast of Africa, told me
that he did not believe in any such relation. He was himself unusually
fair, and had withstood the climate in a wonderful manner. When he first
arrived as a boy on the coast, an old and experienced negro chief
predicted from his appearance that this would prove the case. Dr.
Nicholson, of Antigua, after having attended to this subject, wrote to
me that he did not think that dark-coloured Europeans escaped the
yellow-fever better than those that were light-coloured. Mr. J. M.
Harris altogether denies[330] that Europeans with dark hair withstand a
hot climate better than other men; on the contrary, experience has
taught him in making a selection of men for service on the coast of
Africa, to choose those with red hair. As far, therefore, as these
slight indications serve, there seems no foundation for the hypothesis,
which has been accepted by several writers, that the colour of the black
races may have resulted from darker and darker individuals having
survived in greater numbers, during their exposure to the
fever-generating miasmas of their native countries.

Although with our present knowledge we cannot account for the
strongly-marked differences in colour between the races of man, either
through correlation with constitutional peculiarities, or through the
direct action of climate; yet we must not quite ignore the latter
agency, for there is good reason to believe that some inherited effect
is thus produced.[331]

We have seen in our third chapter that the conditions of life, such as
abundant food and general comfort, affect in a direct manner the
development of the bodily frame, the effects being transmitted. Through
the combined influences of climate and changed habits of life, European
settlers, in the United States undergo, as is generally admitted, a
slight but extraordinarily rapid change of appearance. There is, also, a
considerable body of evidence shewing that in the Southern States the
house-slaves of the third generation present a markedly different
appearance from the field-slaves.[332]

If, however, we look to the races of man, as distributed over the world,
we must infer that their characteristic differences cannot be accounted
for by the direct action of different conditions of life, even after
exposure to them for an enormous period of time. The Esquimaux live
exclusively on animal food; they are clothed in thick fur, and are
exposed to intense cold and to prolonged darkness; yet they do not
differ in any extreme degree from the inhabitants of Southern China, who
live entirely on vegetable food and are exposed almost naked to a hot,
glaring climate. The unclothed Fuegians live on the marine productions
of their inhospitable shores; the Botocudos of Brazil wander about the
hot forests of the interior and live chiefly on vegetable productions;
yet these tribes resemble each other so closely that the Fuegians on
board the “Beagle” were mistaken by some Brazilians for Botocudos. The
Botocudos again, as well as the other inhabitants of tropical America,
are wholly different from the Negroes who inhabit the opposite shores of
the Atlantic, are exposed to a nearly similar climate, and follow nearly
the same habits of life.

Nor can the differences between the races of man be accounted for,
except to a quite insignificant degree, by the inherited effects of the
increased or decreased use of parts. Men who habitually live in canoes,
may have their legs somewhat stunted; those who inhabit lofty regions
have their chests enlarged; and those who constantly use certain
sense-organs have the cavities in which they are lodged somewhat
increased in size, and their features consequently a little modified.
With civilised nations, the reduced size of the jaws from lessened use,
the habitual play of different muscles serving to express different
emotions, and the increased size of the brain from greater intellectual
activity, have together produced a considerable effect on their general
appearance in comparison with savages.[333] It is also possible that
increased bodily stature, with no corresponding increase in the size of
the brain, may have given to some races (judging from the previously
adduced cases of the rabbits) an elongated skull of the dolichocephalic

Lastly, the little-understood principle of correlation will almost
certainly have come into action, as in the case of great muscular
development and strongly projecting supra-orbital ridges. It is not
improbable that the texture of the hair, which differs much in the
different races, may stand in some kind of correlation with the
structure of the skin; for the colour of the hair and skin are certainly
correlated, as is its colour and texture with the Mandans.[334] The
colour of the skin and the odour emitted by it are likewise in some
manner connected. With the breeds of sheep the number of hairs within a
given space and the number of the excretory pores stand in some relation
to each other.[335] If we may judge from the analogy of our domesticated
animals, many modifications of structure in man probably come under this
principle of correlated growth.

We have now seen that the characteristic differences between the races
of man cannot be accounted for in a satisfactory manner by the direct
action of the conditions of life, nor by the effects of the continued
use of parts, nor through the principle of correlation. We are therefore
led to inquire whether slight individual differences, to which man is
eminently liable, may not have been preserved and augmented during a
long series of generations through natural selection. But here we are at
once met by the objection that beneficial variations alone can be thus
preserved; and as far as we are enabled to judge (although always liable
to error on this head) not one of the external differences between the
races of man are of any direct or special service to him. The
intellectual and moral or social faculties must of course be excepted
from this remark; but differences in these faculties can have had little
or no influence on external characters. The variability of all the
characteristic differences between the races, before referred to,
likewise indicates that these differences cannot be of much importance;
for, had they been important, they would long ago have been either fixed
and preserved, or eliminated. In this respect man resembles those forms,
called by naturalists protean or polymorphic, which have remained
extremely variable, owing, as it seems, to their variations being of an
indifferent nature, and consequently to their having escaped the action
of natural selection.

We have thus far been baffled in all our attempts to account for the
differences between the races of man; but there remains one important
agency, namely Sexual Selection, which appears to have acted as
powerfully on man, as on many other animals. I do not intend to assert
that sexual selection will account for all the differences between the
races. An unexplained residuum is left, about which we can in our
ignorance only say, that as individuals are continually born with, for
instance, heads a little rounder or narrower, and with noses a little
longer or shorter, such slight differences might become fixed and
uniform, if the unknown agencies which induced them were to act in a
more constant manner, aided by long-continued intercrossing. Such
modifications come under the provisional class, alluded to in our fourth
chapter, which for the want of a better term have been called
spontaneous variations. Nor do I pretend that the effects of sexual
selection can be indicated with scientific precision; but it can be
shewn that it would be an inexplicable fact if man had not been modified
by this agency, which has acted so powerfully on innumerable animals,
both high and low in the scale. It can further be shewn that the
differences between the races of man, as in colour, hairyness, form of
features, &c., are of the nature which it might have been expected would
have been acted on by sexual selection. But in order to treat this
subject in a fitting manner, I have found it necessary to pass the whole
animal kingdom in review; I have therefore devoted to it the Second Part
of this work. At the close I shall return to man, and, after attempting
to shew how far he has been modified through sexual selection, will give
a brief summary of the chapters in this First Part.




  Secondary sexual characters—Sexual selection—Manner of
  action—Excess of males—Polygamy—The male alone generally
  modified through sexual selection—Eagerness of the
  male—Variability of the male—Choice exerted by the
  female—Sexual compared with natural selection—Inheritance, at
  corresponding periods of life, at corresponding seasons of the
  year, and as limited by sex—Relations between the several
  forms of inheritance—Causes why one sex and the young are not
  modified through sexual selection—Supplement on the
  proportional numbers of the two sexes throughout the animal
  kingdom—On the limitation of the numbers of the two sexes
  through natural selection.

With animals which have their sexes separated, the males necessarily
differ from the females in their organs of reproduction; and these
afford the primary sexual characters. But the sexes often differ in what
Hunter has called secondary sexual characters, which are not directly
connected with the act of reproduction; for instance, in the male
possessing certain organs of sense or locomotion, of which the female is
quite destitute, or in having them more highly-developed, in order that
he may readily find or reach her; or again, in the male having special
organs of prehension so as to hold her securely. These latter organs of
infinitely diversified kinds graduate into, and in some cases can hardly
be distinguished from, those which are commonly ranked as primary, such
as the complex appendages at the apex of the abdomen in male insects.
Unless indeed we confine the term “primary” to the reproductive glands,
it is scarcely possible to decide, as far as the organs of prehension
are concerned, which ought to be called primary and which secondary.

The female often differs from the male in having organs for the
nourishment or protection of her young, as the mammary glands of
mammals, and the abdominal sacks of the marsupials. The male, also, in
some few cases differs from the female in possessing analogous organs,
as the receptacles for the ova possessed by the males of certain fishes,
and those temporarily developed in certain male frogs. Female bees have
a special apparatus for collecting and carrying pollen, and their
ovipositor is modified into a sting for the defence of their larvæ and
the community. In the females of many insects the ovipositor is modified
in the most complex manner for the safe placing of the eggs. Numerous
similar cases could be given, but they do not here concern us. There
are, however, other sexual differences quite disconnected with the
primary organs with which we are more especially concerned—such as the
greater size, strength, and pugnacity of the male, his weapons of
offence or means of defence against rivals, his gaudy colouring and
various ornaments, his power of song, and other such characters.

Besides the foregoing primary and secondary sexual differences, the male
and female sometimes differ in structures connected with different
habits of life, and not at all, or only indirectly, related to the
reproductive functions. Thus the females of certain flies (Culicidæ and
Tabanidæ) are blood-suckers, whilst the males live on flowers and have
their mouths destitute of mandibles.[336] The males alone of certain
moths and of some crustaceans (_e.g._ Tanais) have imperfect, closed
mouths, and cannot feed. The Complemental males of certain cirripedes
live like epiphytic plants either on the female or hermaphrodite form,
and are destitute of a mouth and prehensile limbs. In these cases it is
the male which has been modified and has lost certain important organs,
which the other members of the same group possess. In other cases it is
the female which has lost such parts; for instance, the female glow-worm
is destitute of wings, as are many female moths, some of which never
leave their cocoons. Many female parasitic crustaceans have lost their
natatory legs. In some weevil-beetles (Curculionidæ) there is a great
difference between the male and female in the length of the rostrum or
snout;[337] but the meaning of this and of many analogous differences,
is not at all understood. Differences of structure between the two sexes
in relation to different habits of life are generally confined to the
lower animals; but with some few birds the beak of the male differs from
that of the female. No doubt in most, but apparently not in all these
cases, the differences are indirectly connected with the propagation of
the species: thus a female which has to nourish a multitude of ova will
require more food than the male, and consequently will require special
means for procuring it. A male animal which lived for a very short time
might without detriment lose through disuse its organs for procuring
food; but he would retain his locomotive organs in a perfect state, so
that he might reach the female. The female, on the other hand, might
safely lose her organs for flying, swimming, or walking, if she
gradually acquired habits which rendered such powers useless.

We are, however, here concerned only with that kind of selection, which
I have called sexual selection. This depends on the advantage which
certain individuals have over other individuals of the same sex and
species, in exclusive relation to reproduction. When the two sexes
differ in structure in relation to different habits of life, as in the
cases above mentioned, they have no doubt been modified through natural
selection, accompanied by inheritance limited to one and the same sex.
So again the primary sexual organs, and those for nourishing or
protecting the young, come under this same head; for those individuals
which generated or nourished their offspring best, would leave, _cæteris
paribus_, the greatest number to inherit their superiority; whilst those
which generated or nourished their offspring badly, would leave but few
to inherit their weaker powers. As the male has to search for the
female, he requires for this purpose organs of sense and locomotion, but
if these organs are necessary for the other purposes of life, as is
generally the case, they will have been developed through natural
selection. When the male has found the female he sometimes absolutely
requires prehensile organs to hold her; thus Dr. Wallace informs me that
the males of certain moths cannot unite with the females if their tarsi
or feet are broken. The males of many oceanic crustaceans have their
legs and antennæ modified in an extraordinary manner for the prehension
of the female; hence we may suspect that owing to these animals being
washed about by the waves of the open sea, they absolutely require these
organs in order to propagate their kind, and if so their development
will have been the result of ordinary or natural selection.

When the two sexes follow exactly the same habits of life, and the male
has more highly developed sense or locomotive organs than the female, it
may be that these in their perfected state are indispensable to the male
for finding the female; but in the vast majority of cases, they serve
only to give one male an advantage over another, for the less
well-endowed males, if time were allowed them, would succeed in pairing
with the females; and they would in all other respects, judging from the
structure of the female, be equally well adapted for their ordinary
habits of life. In such cases sexual selection must have come into
action, for the males have acquired their present structure, not from
being better fitted to survive in the struggle for existence, but from
having gained an advantage over other males, and from having transmitted
this advantage to their male offspring alone. It was the importance of
this distinction which led me to designate this form of selection as
sexual selection. So again, if the chief service rendered to the male by
his prehensile organs is to prevent the escape of the female before the
arrival of other males, or when assaulted by them, these organs will
have been perfected through sexual selection, that is by the advantage
acquired by certain males over their rivals. But in most cases it is
scarcely possible to distinguish between the effects of natural and
sexual selection. Whole chapters could easily be filled with details on
the differences between the sexes in their sensory, locomotive, and
prehensile organs. As, however, these structures are not more
interesting than others adapted for the ordinary purposes of life, I
shall almost pass them over, giving only a few instances under each

There are many other structures and instincts which must have been
developed through sexual selection—such as the weapons of offence and
the means of defence possessed by the males for fighting with and
driving away their rivals—their courage and pugnacity—their ornaments
of many kinds—their organs for producing vocal or instrumental
music—and their glands for emitting odours; most of these latter
structures serving only to allure or excite the female. That these
characters are the result of sexual and not of ordinary selection is
clear, as unarmed, unornamented, or unattractive males would succeed
equally well in the battle for life and in leaving a numerous progeny,
if better endowed males were not present. We may infer that this would
be the case, for the females, which are unarmed and unornamented, are
able to survive and procreate their kind. Secondary sexual characters of
the kind just referred to, will be fully discussed in the following
chapters, as they are in many respects interesting, but more especially
as they depend on the will, choice, and rivalry of the individuals of
either sex. When we behold two males fighting for the possession of the
female, or several male birds displaying their gorgeous plumage, and
performing the strangest antics before an assembled body of females, we
cannot doubt that, though led by instinct, they know what they are
about, and consciously exert their mental and bodily powers.

In the same manner as man can improve the breed of his game-cocks by the
selection of those birds which are victorious in the cockpit, so it
appears that the strongest and most vigorous males, or those provided
with the best weapons, have prevailed under nature, and have led to the
improvement of the natural breed or species. Through repeated deadly
contests, a slight degree of variability, if it led to some advantage,
however slight, would suffice for the work of sexual selection; and it
is certain that secondary sexual characters are eminently variable. In
the same manner as man can give beauty, according to his standard of
taste, to his male poultry—can give to the Sebright bantam a new and
elegant plumage, an erect and peculiar carriage—so it appears that in a
state of nature female birds, by having long selected the more
attractive males, have added to their beauty. No doubt this implies
powers of discrimination and taste on the part of the female which will
at first appear extremely improbable; but I hope hereafter to shew that
this is not the case.

From our ignorance on several points, the precise manner in which sexual
selection acts is to a certain extent uncertain. Nevertheless if those
naturalists who already believe in the mutability of species, will read
the following chapters, they will, I think, agree with me that sexual
selection has played an important part in the history of the organic
world. It is certain that with almost all animals there is a struggle
between the males for the possession of the female. This fact is so
notorious that it would be superfluous to give instances. Hence the
females, supposing that their mental capacity sufficed for the exertion
of a choice, could select one out of several males. But in numerous
cases it appears as if it had been specially arranged that there should
be a struggle between many males. Thus with migratory birds, the males
generally arrive before the females at their place of breeding, so that
many males are ready to contend for each female. The bird-catchers
assert that this is invariably the case with the nightingale and
blackcap, as I am informed by Mr. Jenner Weir, who confirms the
statement with respect to the latter species.

Mr. Swaysland of Brighton, who has been in the habit, during the last
forty years, of catching our migratory birds on their first arrival,
writes to me that he has never known the females of any species to
arrive before their males. During one spring he shot thirty-nine males
of Ray’s wagtail (_Budytes Raii_) before he saw a single female. Mr.
Gould has ascertained by dissection, as he informs me, that male snipes
arrive in this country before the females. In the case of fish, at the
period when the salmon ascend our rivers, the males in large numbers are
ready to breed before the females. So it apparently is with frogs and
toads. Throughout the great class of insects the males almost always
emerge from the pupal state before the other sex, so that they generally
swarm for a time before any females can be seen.[338] The cause of this
difference between the males and females in their periods of arrival and
maturity is sufficiently obvious. Those males which annually first
migrated into any country, or which in the spring were first ready to
breed, or were the most eager, would leave the largest number of
offspring; and these would tend to inherit similar instincts and
constitutions. On the whole there can be no doubt that with almost all
animals, in which the sexes are separate, there is a constantly
recurrent struggle between the males for the possession of the females.

Our difficulty in regard to sexual selection lies in understanding how
it is that the males which conquer other males, or those which prove the
most attractive to the females, leave a greater number of offspring to
inherit their superiority than the beaten and less attractive males.
Unless this result followed, the characters which gave to certain males
an advantage over others, could not be perfected and augmented through
sexual selection. When the sexes exist in exactly equal numbers, the
worst-endowed males will ultimately find females (excepting where
polygamy prevails), and leave as many offspring, equally well fitted for
their general habits of life, as the best-endowed males. From various
facts and considerations, I formerly inferred that with most animals, in
which secondary sexual characters were well developed, the males
considerably exceeded the females in number; and this does hold good in
some few cases. If the males were to the females as two to one, or as
three to two, or even in a somewhat lower ratio, the whole affair would
be simple; for the better-armed or more attractive males would leave the
largest number of offspring. But after investigating, as far as
possible, the numerical proportions of the sexes, I do not believe that
any great inequality in number commonly exists. In most cases sexual
selection appears to have been effective in the following manner.

Let us take any species, a bird for instance, and divide the females
inhabiting a district into two equal bodies: the one consisting of the
more vigorous and better-nourished individuals, and the other of the
less vigorous and healthy. The former, there can be little doubt, would
be ready to breed in the spring before the others; and this is the
opinion of Mr. Jenner Weir, who has during many years carefully attended
to the habits of birds. There can also be no doubt that the most
vigorous, healthy, and best-nourished females would on an average
succeed in rearing the largest number of offspring. The males, as we
have seen, are generally ready to breed before the females; of the males
the strongest, and with some species the best armed, drive away the
weaker males; and the former would then unite with the more vigorous and
best-nourished females, as these are the first to breed. Such vigorous
pairs would surely rear a larger number of offspring than the retarded
females, which would be compelled, supposing the sexes to be numerically
equal, to unite with the conquered and less powerful males; and this is
all that is wanted to add, in the course of successive generations, to
the size, strength and courage of the males, or to improve their

But in a multitude of cases the males which conquer other males, do not
obtain possession of the females, independently of choice on the part of
the latter. The courtship of animals is by no means so simple and short
an affair as might be thought. The females are most excited by, or
prefer pairing with, the more ornamented males, or those which are the
best songsters, or play the best antics; but it is obviously probable,
as has been actually observed in some cases, that they would at the same
time prefer the more vigorous and lively males.[339] Thus the more
vigorous females, which are the first to breed, will have the choice of
many males; and though they may not always select the strongest or best
armed, they will select those which are vigorous and well armed, and in
other respects the most attractive. Such early pairs would have the same
advantage in rearing offspring on the female side as above explained,
and nearly the same advantage on the male side. And this apparently has
sufficed during a long course of generations to add not only to the
strength and fighting-powers of the males, but likewise to their
various ornaments or other attractions.

In the converse and much rarer case of the males selecting particular
females, it is plain that those which were the most vigorous and had
conquered others, would have the freest choice; and it is almost certain
that they would select vigorous as well as attractive females. Such
pairs would have an advantage in rearing offspring, more especially if
the male had the power to defend the female during the pairing-season,
as occurs with some of the higher animals, or aided in providing for the
young. The same principles would apply if both sexes mutually preferred
and selected certain individuals of the opposite sex; supposing that
they selected not only the more attractive, but likewise the more
vigorous individuals.

_Numerical Proportion of the Two Sexes._—I have remarked that sexual
selection would be a simple affair if the males considerably exceeded in
number the females. Hence I was led to investigate, as far as I could,
the proportions between the two sexes of as many animals as possible;
but the materials are scanty. I will here give only a brief abstract of
the results, retaining the details for a supplementary discussion, so as
not to interfere with the course of my argument. Domesticated animals
alone afford the opportunity of ascertaining the proportional numbers at
birth; but no records have been specially kept for this purpose. By
indirect means, however, I have collected a considerable body of
statistical data, from which it appears that with most of our domestic
animals the sexes are nearly equal at birth. Thus with race-horses,
25,560 births have been recorded during twenty-one years, and the male
births have been to the female births as 99·7 to 100. With greyhounds
the inequality is greater than with any other animal, for during twelve
years, out of 6878 births, the male births have been as 110·1 to 100
female births. It is, however, in some degree doubtful whether it is
safe to infer that the same proportional numbers would hold good under
natural conditions as under domestication; for slight and unknown
differences in the conditions affect to a certain extent the proportion
of the sexes. Thus with mankind, the male births in England are as
104·5, in Russia as 108·9, and with the Jews of Livornia as 120 _to_ 100
females. The proportion is also mysteriously affected by the
circumstance of the births being legitimate or illegitimate.

For our present purpose we are concerned with the proportion of the
sexes, not at birth, but at maturity, and this adds another element of
doubt; for it is a well ascertained fact that with man a considerably
larger proportion of males than of females die before or during birth,
and during the first few years of infancy. So it almost certainly is
with male lambs, and so it may be with the males of other animals. The
males of some animals kill each other by fighting; or they drive each
other about until they become greatly emaciated. They must, also, whilst
wandering about in eager search for the females, be often exposed to
various dangers. With many kinds of fish the males are much smaller than
the females, and they are believed often to be devoured by the latter or
by other fishes. With some birds the females appear to die in larger
proportion than the males: they are also liable to be destroyed on their
nests, or whilst in charge of their young. With insects the female larvæ
are often larger than those of the males, and would consequently be more
likely to be devoured: in some cases the mature females are less active
and less rapid in their movements than the males, and would not be so
well able to escape from danger. Hence, with animals in a state of
nature, in order to judge of the proportions of the sexes at maturity,
we must rely on mere estimation; and this, except perhaps when the
inequality is strongly marked, is but little trustworthy. Nevertheless,
as far as a judgment can be formed, we may conclude from the facts given
in the supplement, that the males of some few mammals, of many birds, of
some fish and insects, considerably exceed in number the females.

The proportion between the sexes fluctuates slightly during successive
years: thus with race-horses, for every 100 females born, the males
varied from 107.1 in one year to 92.6 in another year, and with
greyhounds from 116.3 to 95.3. But had larger numbers been tabulated
throughout a more extensive area than England, these fluctuations would
probably have disappeared; and such as they are, they would hardly
suffice to lead under a state of nature to the effective action of
sexual selection. Nevertheless with some few wild animals, the
proportions seem, as shewn in the supplement, to fluctuate either during
different seasons or in different localities in a sufficient degree to
lead to such action. For it should be observed that any advantage gained
during certain years or in certain localities by those males which were
able to conquer other males, or were the most attractive to the females,
would probably be transmitted to the offspring and would not
subsequently be eliminated. During the succeeding seasons, when from the
equality of the sexes every male was everywhere able to procure a
female, the stronger or more attractive males previously produced would
still have at least as good a chance of leaving offspring as the less
strong or less attractive.

_Polygamy._—The practice of polygamy leads to the same results as
would follow from an actual inequality in the number of the sexes; for
if each male secures two or more females, many males will not be able to
pair; and the latter assuredly will be the weaker or less attractive
individuals. Many mammals and some few birds are polygamous, but with
animals belonging to the lower classes I have found no evidence of this
habit. The intellectual powers of such animals are, perhaps, not
sufficient to lead them to collect and guard a harem of females. That
some relation exists between polygamy and the development of secondary
sexual characters, appears nearly certain; and this supports the view
that a numerical preponderance of males would be eminently favourable to
the action of sexual selection. Nevertheless many animals, especially
birds, which are strictly monogamous, display strongly-marked secondary
sexual characters; whilst some few animals, which are polygamous, are
not thus characterised.

We will first briefly run through the class of mammals, and then turn to
birds. The gorilla seems to be a polygamist, and the male differs
considerably from the female; so it is with some baboons which live in
herds containing twice as many adult females as males. In South America
the _Mycetes caraya_ presents well-marked sexual differences in colour,
beard, and vocal organs, and the male generally lives with two or three
wives: the male of the _Cebus capucinus_ differs somewhat from the
female, and appears to be polygamous.[340] Little is known on this head
with respect to most other monkeys, but some species are strictly
monogamous. The ruminants are eminently polygamous, and they more
frequently present sexual differences than almost any other group of
mammals, especially in their weapons, but likewise in other characters.
Most deer, cattle, and sheep are polygamous; as are most antelopes,
though some of the latter are monogamous. Sir Andrew Smith, in speaking
of the antelopes of South Africa, says that in herds of about a dozen
there was rarely more than one mature male. The Asiatic _Antilope saiga_
appears to be the most inordinate polygamist in the world; for
Pallas[341] states that the male drives away all rivals, and collects a
herd of about a hundred, consisting of females and kids: the female is
hornless and has softer hair, but does not otherwise differ much from
the male. The horse is polygamous, but, except in his greater size and
in the proportions of his body, differs but little from the mare. The
wild boar, in his great tusks and some other characters, presents
well-marked sexual characters; in Europe and in India he leads a
solitary life, except during the breeding-season; but at this season he
consorts in India with several females, as Sir W. Elliot, who has had
large experience in observing this animal, believes: whether this holds
good in Europe is doubtful, but is supported by some statements. The
adult male Indian elephant, like the boar, passes much of his time in
solitude; but when associating with others, “it is rare to find,” as Dr.
Campbell states, “more than one male with a whole herd of females.” The
larger males expel or kill the smaller and weaker ones. The male differs
from the female by his immense tusks and greater size, strength, and
endurance; so great is the difference in these latter respects, that
the males when caught are valued at twenty per cent. above the
females.[342] With other pachydermatous animals the sexes differ very
little or not at all, and they are not, as far as known, polygamists.
Hardly a single species amongst the Cheiroptera and Edentata, or in the
great Orders of the Rodents and Insectivora, presents well-developed
secondary sexual differences; and I can find no account of any species
being polygamous, excepting, perhaps, the common rat, the males of
which, as some rat-catchers affirm, live with several females.

The lion in South Africa, as I hear from Sir Andrew Smith, sometimes
lives with a single female, but generally with more than one, and, in
one case, was found with as many as five females, so that he is
polygamous. He is, as far as I can discover, the sole polygamist in the
whole group of the terrestrial Carnivora, and he alone presents
well-marked sexual characters. If, however, we turn to the marine
Carnivora, the case is widely different; for many species of seals
offer, as we shall hereafter see, extraordinary sexual differences, and
they are eminently polygamous. Thus the male sea-elephant of the
Southern Ocean, always possesses, according to Péron, several females,
and the sea-lion of Forster is said to be surrounded by from twenty to
thirty females. In the North, the male sea-bear of Steller is
accompanied by even a greater number of females.

With respect to birds, many species, the sexes of which differ greatly
from each other, are certainly monogamous. In Great Britain we see
well-marked sexual differences in, for instance, the wild-duck which
pairs with a single female, with the common blackbird, and with the
bullfinch which is said to pair for life. So it is, as I am informed by
Mr. Wallace, with the Chatterers or Cotingidæ of South America, and
numerous other birds. In several groups I have not been able to discover
whether the species are polygamous or monogamous. Lesson says that birds
of paradise, so remarkable for their sexual differences, are polygamous,
but Mr. Wallace doubts whether he had sufficient evidence. Mr. Salvin
informs me that he has been led to believe that humming-birds are
polygamous. The male widow-bird; remarkable for his caudal plumes,
certainly seems to be a polygamist.[343] I have been assured by Mr.
Jenner Weir and by others, that three starlings not rarely frequent the
same nest; but whether this is a case of polygamy or polyandry has not
been ascertained.

The Gallinaceæ present almost as strongly marked sexual differences as
birds of paradise or humming-birds, and many of the species are, as is
well known, polygamous; others being strictly monogamous. What a
contrast is presented between the sexes by the polygamous peacock or
pheasant, and the monogamous guinea-fowl or partridge! Many similar
cases could be given, as in the grouse tribe, in which the males of the
polygamous capercailzie and black-cock differ greatly from the females;
whilst the sexes of the monogamous red grouse and ptarmigan differ very
little. Amongst the Cursores, no great number of species offer
strongly-marked sexual differences, except the bustards, and the great
bustard (_Otis tarda_), is said to be polygamous. With the Grallatores,
extremely few species differ sexually, but the ruff (_Machetes pugnax_)
affords a strong exception, and this species is believed by Montagu to
be a polygamist. Hence it appears that with birds there often exists a
close relation between polygamy and the development of strongly-marked
sexual differences. On asking Mr. Bartlett, at the Zoological Gardens,
who has had such large experience with birds, whether the male tragopan
(one of the Gallinaceæ) was polygamous, I was struck by his answering,
“I do not know, but should think so from his splendid colours.”

It deserves notice that the instinct of pairing with a single female is
easily lost under domestication. The wild-duck is strictly monogamous,
the domestic-duck highly polygamous. The Rev. W. D. Fox informs me that
with some half-tamed wild-ducks, kept on a large pond in his
neighbourhood, so many mallards were shot by the gamekeeper that only
one was left for every seven or eight females; yet unusually large
broods were reared. The guinea-fowl is strictly monogamous; but Mr. Fox
finds that his birds succeed best when he keeps one cock to two or three
hens.[344] Canary-birds pair in a state of nature, but the breeders in
England successfully put one male to four or five females; nevertheless
the first female, as Mr. Fox has been assured, is alone treated as the
wife, she and her young ones being fed by him; the others are treated as
concubines. I have noticed these cases, as it renders it in some degree
probable that monogamous species, in a state of nature, might readily
become either temporarily or permanently polygamous.

With respect to reptiles and fishes, too little is known of their habits
to enable us to speak of their marriage arrangements. The stickle-back
Gasterosteus, however, is said to be a polygamist;[345] and the male
during the breeding-season differs conspicuously from the female.

To sum up on the means through which, as far as we can judge, sexual
selection has led to the development of secondary sexual characters. It
has been shewn that the largest number of vigorous offspring will be
reared from the pairing of the strongest and best-armed males, which
have conquered other males, with the most vigorous and best-nourished
females, which are the first to breed in the spring. Such females, if
they select the more attractive, and at the same time vigorous, males,
will rear a larger number of offspring than the retarded females, which
must pair with the less vigorous and less attractive males. So it will
be if the more vigorous males select the more attractive and at the same
time healthy and vigorous females; and this will especially hold good if
the male defends the female, and aids in providing food for the young.
The advantage thus gained by the more vigorous pairs in rearing a larger
number of offspring has apparently sufficed to render sexual selection
efficient. But a large preponderance in number of the males over the
females would be still more efficient; whether the preponderance was
only occasional and local, or permanent; whether it occurred at birth,
or subsequently from the greater destruction of the females; or whether
it indirectly followed from the practice of polygamy.

_The Male generally more modified than the Female._—Throughout the
animal kingdom, when the sexes differ from each other in external
appearance, it is the male which, with rare exceptions, has been chiefly
modified; for the female still remains more like the young of her own
species, and more like the other members of the same group. The cause of
this seems to lie in the males of almost all animals having stronger
passions than the females. Hence it is the males that fight together and
sedulously display their charms before the females; and those which are
victorious transmit their superiority to their male offspring. Why the
males do not transmit their characters to both sexes will hereafter be
considered. That the males of all mammals eagerly pursue the females is
notorious to every one. So it is with birds; but many male birds do not
so much pursue the female, as display their plumage, perform strange
antics, and pour forth their song, in her presence. With the few fish
which have been observed, the male seems much more eager than the
female; and so it is with alligators, and apparently with Batrachians.
Throughout the enormous class of insects, as Kirby remarks,[346] “the
law is, that the male shall seek the female.” With spiders and
crustaceans, as I hear from two great authorities, Mr. Blackwall and Mr.
C. Spence Bate, the males are more active and more erratic in their
habits than the females. With insects and crustaceans, when the organs
of sense or locomotion are present in the one sex and absent in the
other, or when, as is frequently the case, they are more highly
developed in the one than the other, it is almost invariably the male,
as far as I can discover, which retains such organs, or has them most
developed; and this shews that the male is the more active member in the
courtship of the sexes.[347]

The female, on the other hand, with the rarest exception, is less eager
than the male. As the illustrious Hunter[348] long ago observed, she
generally “requires to be courted;” she is coy, and may often be seen
endeavouring for a long time to escape from the male. Every one who has
attended to the habits of animals will be able to call to mind instances
of this kind. Judging from various facts, hereafter to be given, and
from the results which may fairly be attributed to sexual selection, the
female, though comparatively passive, generally exerts some choice and
accepts one male in preference to others. Or she may accept, as
appearances would sometimes lead us to believe, not the male which is
the most attractive to her, but the one which is the least distasteful.
The exertion of some choice on the part of the female seems almost as
general a law as the eagerness of the male.

We are naturally led to enquire why the male in so many and such widely
distinct classes has been rendered more eager than the female, so that
he searches for her and plays the more active part in courtship. It
would be no advantage and some loss of power if both sexes were mutually
to search for each other; but why should the male almost always be the
seeker? With plants, the ovules after fertilisation have to be nourished
for a time; hence the pollen is necessarily brought to the female
organs—being placed on the stigma, through the agency of insects or of
the wind, or by the spontaneous movements of the stamens; and with the
Algæ, &c., by the locomotive power of the antherozooids. With
lowly-organised animals permanently affixed to the same spot and having
their sexes separate, the male element is invariably brought to the
female; and we can see the reason; for the ova, even if detached before
being fertilised and not requiring subsequent nourishment or protection,
would be, from their larger relative size, less easily transported than
the male element. Hence plants[349] and many of the lower animals are,
in this respect, analogous. In the case of animals not affixed to the
same spot, but enclosed within a shell with no power of protruding any
part of their bodies, and in the case of animals having little power of
locomotion, the males must trust the fertilising element to the risk of
at least a short transit through the waters of the sea. It would,
therefore, be a great advantage to such animals, as their organisation
became perfected, if the males when ready to emit the fertilising
element, were to acquire the habit of approaching the female as closely
as possible. The males of various lowly-organised animals having thus
aboriginally acquired the habit of approaching and seeking the females,
the same habit would naturally be transmitted to their more highly
developed male descendants; and in order that they should become
efficient seekers, they would have to be endowed with strong passions.
The acquirement of such passions would naturally follow from the more
eager males leaving a larger number of offspring than the less eager.

The great eagerness of the male has thus indirectly led to the much
more frequent development of secondary sexual characters in the male
than in the female. But the development of such characters will have
been much aided, if the conclusion at which I arrived after studying
domesticated animals, can be trusted, namely, that the male is more
liable to vary than the female. I am aware how difficult it is to verify
a conclusion of this kind. Some slight evidence, however, can be gained
by comparing the two sexes in mankind, as man has been more carefully
observed than any other animal. During the Novara Expedition[350] a vast
number of measurements of various parts of the body in different races
were made, and the men were found in almost every case to present a
greater range of variation than the women; but I shall have to recur to
this subject in a future chapter. Mr. J. Wood,[351] who has carefully
attended to the variation of the muscles in man, puts in italics the
conclusion that “the greatest number of abnormalities in each subject is
found in the males.” He had previously remarked that “altogether in 102
subjects the varieties of redundancy were found to be half as many again
as in females, contrasting widely with the greater frequency of
deficiency in females before described.” Professor Macalister like wise
remarks[352] that variations in the muscles “are probably more common in
males than females.” Certain muscles which are not normally present in
mankind are also more frequently developed in the male than in the
female sex, although exceptions to this rule are said to occur. Dr.
Burt Wilder[353] has tabulated the cases of 152 individuals with
supernumerary digits, of which 86 were males, and 39, or less than half,
females; the remaining 27 being of unknown sex. It should not, however,
be overlooked that women would more frequently endeavour to conceal a
deformity of this kind than men. Whether the large proportional number
of deaths of the male offspring of man and apparently of sheep, compared
with the female offspring, before, during, and shortly after birth (see
supplement), has any relation to a stronger tendency in the organs of
the male to vary and thus to become abnormal in structure or function, I
will not pretend to conjecture.

In various classes of animals a few exceptional cases occur, in which
the female instead of the male has acquired well pronounced secondary
sexual characters, such as brighter colours, greater size, strength, or
pugnacity. With birds, as we shall hereafter see, there has sometimes
been a complete transposition of the ordinary characters proper to each
sex; the females having become the more eager in courtship, the males
remaining comparatively passive, but apparently selecting, as we may
infer from the results, the more attractive females. Certain female
birds have thus been rendered more highly coloured or otherwise
ornamented, as well as more powerful and pugnacious than the males,
these characters being transmitted to the female offspring alone.

It may be suggested that in some cases a double process of selection has
been carried on; the males having selected the more attractive females,
and the latter the more attractive males. This process however, though
it might lead to the modification of both sexes, would not make the one
sex different from the other, unless indeed their taste for the
beautiful differed; but this is a supposition too improbable in the case
of any animal, excepting man, to be worth considering. There are,
however, many animals, in which the sexes resemble each other, both
being furnished with the same ornaments, which analogy would lead us to
attribute to the agency of sexual selection. In such cases it may be
suggested with more plausibility, that there has been a double or mutual
process of sexual selection; the more vigorous and precocious females
having selected the more attractive and vigorous males, the latter
having rejected all except the more attractive females. But from what we
know of the habits of animals, this view is hardly probable, the male
being generally eager to pair with any female. It is more probable that
the ornaments common to both sexes were acquired by one sex, generally
the male, and then transmitted to the offspring of both sexes. If,
indeed, during a lengthened period the males of any species were greatly
to exceed the females in number, and then during another lengthened
period under different conditions the reverse were to occur, a double,
but not simultaneous, process of sexual selection might easily be
carried on, by which the two sexes might be rendered widely different.

We shall hereafter see that many animals exist, of which neither sex is
brilliantly coloured or provided with special ornaments, and yet the
members of both sexes or of one alone have probably been modified
through sexual selection. The absence of bright tints or other ornaments
may be the result of variations of the right kind never having occurred,
or of the animals themselves preferring simple colours, such as plain
black or white. Obscure colours have often been acquired through natural
selection for the sake of protection, and the acquirement through
sexual selection of conspicuous colours, may have been checked from the
danger thus incurred. But in other cases the males have probably
struggled together during long ages, through brute force, or by the
display of their charms, or by both means combined, and yet no effect
will have been produced unless a larger number of offspring were left by
the more successful males to inherit their superiority, than by the less
successful males; and this, as previously shewn, depends on various
complex contingencies.

Sexual selection acts in a less rigorous manner than natural selection.
The latter produces its effects by the life or death at all ages of the
more or less successful individuals. Death, indeed, not rarely ensues
from the conflicts of rival males. But generally the less successful
male merely fails to obtain a female, or obtains later in the season a
retarded and less vigorous female, or, if polygamous, obtains fewer
females; so that they leave fewer, or less vigorous, or no offspring. In
regard to structures acquired through ordinary or natural selection,
there is in most cases, as long as the conditions of life remain the
same, a limit to the amount of advantageous modification in relation to
certain special ends; but in regard to structures adapted to make one
male victorious over another, either in fighting or in charming the
female, there is no definite limit to the amount of advantageous
modification; so that as long as the proper variations arise the work of
sexual selection will go on. This circumstance may partly account for
the frequent and extraordinary amount of variability presented by
secondary sexual characters. Nevertheless, natural selection will
determine that characters of this kind shall not be acquired by the
victorious males, which would be injurious to them in any high degree,
either by expending too much of their vital powers, or by exposing them
to any great danger. The development, however, of certain structures—of
the horns, for instance, in certain stags—has been carried to a
wonderful extreme; and in some instances to an extreme which, as far as
the general conditions of life are concerned, must be slightly injurious
to the male. From this fact we learn that the advantages which favoured
males have derived from conquering other males in battle or courtship,
and thus leaving a numerous progeny, have been in the long run greater
than those derived from rather more perfect adaptation to the external
conditions of life. We shall further see, and this could never have been
anticipated, that the power to charm the female has been in some few
instances more important than the power to conquer other males in


In order to understand how sexual selection has acted, and in the course
of ages has produced conspicuous results with many animals of many
classes, it is necessary to bear in mind the laws of inheritance, as far
as they are known. Two distinct elements are included under the term
“inheritance,” namely the transmission and the development of
characters; but as these generally go together, the distinction is often
overlooked. We see this distinction in those characters which are
transmitted through the early years of life, but are developed only at
maturity or during old age. We see the same distinction more clearly
with secondary sexual characters, for these are transmitted through both
sexes, though developed in one alone. That they are present in both
sexes, is manifest when two species, having strongly-marked sexual
characters, are crossed, for each transmits the characters proper to
its own male and female sex to the hybrid offspring of both sexes. The
same fact is likewise manifest, when characters proper to the male are
occasionally developed in the female when she grows old or becomes
diseased; and so conversely with the male. Again, characters
occasionally appear, as if transferred from the male to the female, as
when, in certain breeds of the fowl, spurs regularly appear in the young
and healthy females; but in truth they are simply developed in the
female; for in every breed each detail in the structure of the spur is
transmitted through the female to her male offspring. In all cases of
reversion, characters are transmitted through two, three, or many
generations, and are then under certain unknown favourable conditions
developed. This important distinction between transmission and
development will be easiest kept in mind by the aid of the hypothesis of
pangenesis, whether or not it be accepted as true. According to this
hypothesis, every unit or cell of the body throws off gemmules or
undeveloped atoms, which are transmitted to the offspring of both sexes,
and are multiplied by self-division. They may remain undeveloped during
the early years of life or during successive generations; their
development into units or cells, like those from which they were
derived, depending on their affinity for, and union with, other units or
cells previously developed in the due order of growth.

_Inheritance at Corresponding Periods of Life._—This tendency is well
established. If a new character appears in an animal whilst young,
whether it endures throughout life or lasts only for a time, it will
reappear, as a general rule, at the same age and in the same manner in
the offspring. If, on the other hand, a new character appears at
maturity, or even during old age, it tends to reappear in the offspring
at the same advanced age. When deviations from this rule occur, the
transmitted characters much oftener appear before than after the
corresponding age. As I have discussed this subject at sufficient length
in another work,[354] I will here merely give two or three instances,
for the sake of recalling the subject to the reader’s mind. In several
breeds of the Fowl, the chickens whilst covered with down, in their
first true plumage, and in their adult plumage, differ greatly from each
other, as well as from their common parent-form, the _Gallus bankiva_;
and these characters are faithfully transmitted by each breed to their
offspring at the corresponding period of life. For instance, the
chickens of spangled Hamburghs, whilst covered with down, have a few
dark spots on the head and rump, but are not longitudinally striped, as
in many other breeds; in their first true plumage, “they are beautifully
pencilled,” that is each feather is transversely marked by numerous dark
bars; but in their second plumage the feathers all become spangled or
tipped with a dark round spot.[355] Hence in this breed variations have
occurred and have been transmitted at three distinct periods of life.
The Pigeon offers a more remarkable case, because the aboriginal
parent-species does not undergo with advancing age any change of
plumage, excepting that at maturity the breast becomes more iridescent;
yet there are breeds which do not acquire their characteristic colours
until they have moulted two, three, or four times; and these
modifications of plumage are regularly transmitted.

_Inheritance at Corresponding Seasons of the Year._—With animals in a
state of nature innumerable instances occur of characters periodically
appearing at different seasons. We see this with the horns of the stag,
and with the fur of arctic animals which becomes thick and white during
the winter. Numerous birds acquire bright colours and other decorations
during the breeding-season alone. I can throw but little light on this
form of inheritance from facts observed under domestication. Pallas
states,[356] that in Siberia domestic cattle and horses periodically
become lighter-coloured during the winter; and I have observed a similar
marked change of colour in certain ponies in England. Although I do not
know that this tendency to assume a differently coloured coat during
different seasons of the year is transmitted, yet it probably is so, as
all shades of colour are strongly inherited by the horse. Nor is this
form of inheritance, as limited by season, more remarkable than
inheritance as limited by age or sex.

_Inheritance as Limited by Sex._—The equal transmission of characters
to both, sexes is the commonest form of inheritance, at least with those
animals which do not present strongly-marked sexual differences, and
indeed with many of these. But characters are not rarely transferred
exclusively to that sex, in which they first appeared. Ample evidence on
this head has been advanced in my work on Variation under
Domestication; but a few instances may here be given. There are breeds
of the sheep and goat, in which the horns of the male differ greatly in
shape from those of the female; and these differences, acquired under
domestication, are regularly transmitted to the same sex. With
tortoise-shell cats the females alone, as a general rule, are thus
coloured, the males being rusty-red. With most breeds of the fowl, the
characters proper to each sex are transmitted to the same sex alone. So
general is this form of transmission that it is an anomaly when we see
in certain breeds variations transmitted equally to both sexes. There
are also certain sub-breeds of the fowl in which the males can hardly be
distinguished from each other, whilst the females differ considerably in
colour. With the pigeon the sexes of the parent-species do not differ in
any external character; nevertheless in certain domesticated breeds the
male is differently coloured from the female.[357] The wattle in the
English Carrier pigeon and the crop in the Pouter are more highly
developed in the male than in the female; and although these characters
have been gained through long-continued selection by man, the difference
between the two sexes is wholly due to the form of inheritance which has
prevailed; for it has arisen, not from, but rather in opposition to, the
wishes of the breeder.

Most of our domestic races have been formed by the accumulation of many
slight variations; and as some of the successive steps have been
transmitted to one sex alone, and some to both sexes, we find in the
different breeds of the same species all gradations between great sexual
dissimilarity and complete similarity. Instances have already been
given with the breeds of the fowl and pigeon; and under nature analogous
cases are of frequent occurrence. With animals under domestication, but
whether under nature I will not venture to say, one sex may lose
characters proper to it, and may thus come to resemble to a certain
extent the opposite sex; for instance, the males of some breeds of the
fowl have lost their masculine plumes and hackles. On the other hand the
differences between the sexes may be increased under domestication, as
with merino sheep, in which the ewes have lost their horns. Again,
characters proper to one sex may suddenly appear in the other sex; as
with those sub-breeds of the fowl in which the hens whilst young acquire
spurs; or, as in certain Polish sub-breeds, in which the females, as
there is reason to believe, originally acquired a crest, and
subsequently transferred it to the males. All these cases are
intelligible on the hypothesis of pangenesis; for they depend on the
gemmules of certain units of the body, although present in both sexes,
becoming through the influence of domestication dormant in the one sex;
or if naturally dormant, becoming developed.

There is one difficult question which it will be convenient to defer to
a future chapter; namely, whether a character at first developed in both
sexes, can be rendered through selection limited in its development to
one sex alone. If, for instance, a breeder observed that some of his
pigeons (in which species characters are usually transferred in an equal
degree to both sexes) varied into pale blue; could he by long-continued
selection make a breed, in which the males alone should be of this tint,
whilst the females remained unchanged? I will here only say, that this,
though perhaps not impossible, would be extremely difficult; for the
natural result of breeding from the pale-blue males would be to change
his whole stock, including both sexes, into this tint. If, however,
variations of the desired tint appeared, which were from the first
limited in their development to the male sex, there would not be the
least difficulty in making a breed characterised by the two sexes being
of a different colour, as indeed has been effected with a Belgian breed,
in which the males alone are streaked with black. In a similar manner,
if any variation appeared in a female pigeon, which was from the first
sexually limited in its development, it would be easy to make a breed
with the females alone thus characterised; but if the variation was not
thus originally limited, the process would be extremely difficult,
perhaps impossible.

_On the Relation between the period of Development of a Character and
its transmission to one sex or to both sexes._—Why certain characters
should be inherited by both sexes, and other characters by one sex
alone, namely by that sex in which the character first appeared, is in
most cases quite unknown. We cannot even conjecture why with certain
sub-breeds of the pigeon, black striæ, though transmitted through the
female, should be developed in the male alone, whilst every other
character is equally transferred to both sexes. Why, again, with cats,
the tortoise-shell colour should, with rare exceptions, be developed in
the female alone. The very same characters, such as deficient or
supernumerary digits, colour-blindness, &c., may with mankind be
inherited by the males alone of one family, and in another family by the
females alone, though in both cases transmitted through the opposite as
well as the same sex.[358] Although we are thus ignorant, two rules
often hold good, namely that variations which, first appear in either
sex at a late period of life, tend to be developed in the same sex
alone; whilst variations which first appear early in life in either sex
tend to be developed in both sexes. I am, however, far from supposing
that this is the sole determining cause. As I have not elsewhere
discussed this subject, and as it has an important bearing on sexual
selection, I must here enter into lengthy and somewhat intricate

It is in itself probable that any character appearing at an early age
would tend to be inherited equally by both sexes, for the sexes do not
differ much in constitution, before the power of reproduction is gained.
On the other hand, after this power has been gained and the sexes have
come to differ in constitution, the gemmules (if I may again use the
language of pangenesis) which are cast off from each varying part in the
one sex would be much more likely to possess the proper affinities for
uniting with the tissues of the same sex, and thus becoming developed,
than with those of the opposite sex.

I was first led to infer that a relation of this kind exists, from the
fact that whenever and in whatever manner the adult male has come to
differ from the adult female, he differs in the same manner from the
young of both sexes. The generality of this fact is quite remarkable: it
holds good with almost all mammals, birds, amphibians, and fishes; also
with many crustaceans, spiders and some few insects, namely certain
orthoptera and libellulæ. In all these cases the variations, through the
accumulation of which the male acquired his proper masculine characters,
must have occurred at a somewhat late period of life; otherwise the
young males would have been similarly characterised; and conformably
with our rule, they are transmitted to and developed in the adult males
alone. When, on the other hand, the adult male closely resembles the
young of both sexes (these, with rare exceptions, being alike), he
generally resembles the adult female; and in most of these cases the
variations through which the young and old acquired their present
characters, probably occurred in conformity with our rule during youth.
But there is here room for doubt, as characters are sometimes
transferred to the offspring at an earlier age than that at which they
first appeared in the parents, so that the parents may have varied when
adult, and have transferred their characters to their offspring whilst
young. There are, moreover, many animals, in which the two sexes closely
resemble each other, and yet both differ from their young; and here the
characters of the adults must have been acquired late in life;
nevertheless, these characters in apparent contradiction to our rule,
are transferred to both sexes. We must not, however, overlook the
possibility or even probability of successive variations of the same
nature sometimes occurring, under exposure to similar conditions,
simultaneously in both sexes at a rather late period of life; and in
this case the variations would be transferred to the offspring of both
sexes at a corresponding late age; and there would be no real
contradiction to our rule of the variations which occur late in life
being transferred exclusively to the sex in which they first appeared.
This latter rule seems to hold true more generally than the second rule,
namely, that variations which occur in either sex early in life tend to
be transferred to both sexes. As it was obviously impossible even to
estimate in how large a number of cases throughout the animal kingdom
these two propositions hold good, it occurred to me to investigate some
striking or crucial instances, and to rely on the result.

An excellent case for investigation is afforded by the Deer Family. In
all the species, excepting one, the horns are developed in the male
alone, though certainly transmitted through the female, and capable of
occasional abnormal development in her. In the reindeer, on the other
hand, the female is provided with horns; so that in this species, the
horns ought, according to our rule, to appear early in life, long before
the two sexes had arrived at maturity and had come to differ much in
constitution. In all the other species of deer the horns ought to appear
later in life, leading to their development in that sex alone, in which
they first appeared in the progenitor of the whole Family. Now in seven
species, belonging to distinct sections of the family and inhabiting
different regions, in which the stags alone bear horns, I find that the
horns first appear at periods varying from nine months after birth in
the roebuck to ten or twelve or even more months in the stags of the six
other larger species.[359] But with the reindeer the case is widely
different, for as I hear from Prof. Nilsson, who kindly made special
enquiries for me in Lapland, the horns appear in the young animals
within four or five weeks after birth, and at the same time in both
sexes. So that here we have a structure, developed at a most unusually
early age in one species of the family, and common to both sexes in this
one species.

In several kinds of antelopes the males alone are provided with horns,
whilst in the greater number both sexes have horns. With respect to the
period of development, Mr. Blyth informs me that there lived at one time
in the Zoological Gardens a young koodoo (_Ant. strepsiceros_), in which
species the males alone are horned, and the young of a closely-allied
species, viz. the eland (_Ant. oreas_), in which both sexes are horned.
Now in strict conformity with our rule, in the young male koodoo,
although arrived at the age of ten months, the horns were remarkably
small considering the size ultimately attained by them: whilst in the
young male eland, although only three months old, the horns were already
very much larger than in the koodoo. It is also worth notice that in the
prong-horned antelope,[360] in which species the horns, though present
in both sexes, are almost rudimentary in the female, they do not appear
until about five or six months after birth. With sheep, goats, and
cattle, in which the horns are well developed in both sexes, though not
quite equal in size, they can be felt, or even seen, at birth or soon
afterwards.[361] Our rule, however, fails in regard to some breeds of
sheep, for instance merinos, in which the rams alone are horned; for I
cannot find on enquiry,[362] that the horns are developed later in life
in this breed than in ordinary sheep in which both sexes are horned. But
with domesticated sheep the presence or absence of horns is not a firmly
fixed character; a certain proportion of the merino ewes bearing small
horns, and some of the rams being hornless; whilst with ordinary sheep
hornless ewes are occasionally produced.

In most of the species of the splendid family of the Pheasants, the
males differ conspicuously from the females, and they acquire their
ornaments at a rather late period of life. The eared pheasant
(_Crossoptilon auritum_), however, offers a remarkable exception, for
both sexes possess the fine caudal plumes, the large ear-tufts and the
crimson velvet about the head; and I find on enquiry in the Zoological
Gardens that all these characters, in accordance with our rule, appear
very early in life. The adult male can, however, be distinguished from
the adult female by one character, namely by the presence of spurs; and
conformably with our rule, these do not begin to be developed, as I am
assured by Mr. Bartlett, before the age of six months, and even at this
age, can hardly be distinguished in the two sexes.[363] The male and
female Peacock differ conspicuously from each other in almost every
part of their plumage, except in the elegant head-crest, which is common
to both sexes; and this is developed very early in life, long before the
other ornaments which are confined to the male. The wild-duck offers an
analogous case, for the beautiful green speculum on the wings is common
to both sexes, though duller and somewhat smaller in the female, and it
is developed early in life, whilst the curled tail-feathers and other
ornaments peculiar to the male are developed later.[364] Between such
extreme cases of close sexual resemblance and wide dissimilarity, as
those of the Crossoptilon and peacock, many intermediate ones could be
given, in which the characters follow in their order of development our
two rules.

As most insects emerge from their pupal state in a mature condition, it
is doubtful whether the period of development determines the
transference of their characters to one or both sexes. But we do not
know that the coloured scales, for instance, in two species of
butterflies, in one of which the sexes differ in colour, whilst in the
other they are alike, are developed at the same relative age in the
cocoon. Nor do we know whether all the scales are simultaneously
developed on the wings of the same species of butterfly, in which
certain coloured marks are confined to one sex, whilst other marks are
common to both sexes. A difference of this kind in the period of
development is not so improbable as it may at first appear; for with the
Orthoptera, which assume their adult state, not by a single
metamorphosis, but by a succession of moults, the young males of some
species at first resemble the females, and acquire their distinctive
masculine characters only during a later moult. Strictly analogous cases
occur during the successive moults of certain male crustaceans.

We have as yet only considered the transference of characters,
relatively to their period of development, with species in a natural
state; we will now turn to domesticated animals; first touching on
monstrosities and diseases. The presence of supernumerary digits, and
the absence of certain phalanges, must be determined at an early
embryonic period—the tendency to profuse bleeding is at least
congenital, as is probably colour-blindness—yet these peculiarities,
and other similar ones, are often limited in their transmission to one
sex; so that the rule that characters which are developed at an early
period tend to be transmitted to both sexes, here wholly fails. But this
rule, as before remarked, does not appear to be nearly so generally true
as the converse proposition, namely, that characters which appear late
in life in one sex are transmitted exclusively to the same sex. From the
fact of the above abnormal peculiarities becoming attached to one sex,
long before the sexual functions are active, we may infer that there
must be a difference of some kind between the sexes at an extremely
early age. With respect to sexually-limited diseases, we know too little
of the period at which they originate, to draw any fair conclusion.
Gout, however, seems to fall under our rule; for it is generally caused
by intemperance after early youth, and is transmitted from the father to
his sons in a much more marked manner than to his daughters.

In the various domestic breeds of sheep, goats, and cattle, the males
differ from their respective females in the shape or development of
their horns, forehead, mane, dewlap, tail, and hump on the shoulders;
and these peculiarities, in accordance with our rule, are not fully
developed until rather late in life. With dogs, the sexes do not differ,
except that in certain breeds, especially in the Scotch deer-hound, the
male is much larger and heavier than the female; and as we shall see in
a future chapter, the male goes on increasing in size to an unusually
late period of life, which will account, according to our rule, for his
increased size being transmitted to his male offspring alone. On the
other hand, the tortoise-shell colour of the hair, which is confined to
female cats, is quite distinct at birth, and this case violates our
rule. There is a breed of pigeons in which the males alone are streaked
with black, and the streaks can be detected even in the nestlings; but
they become more conspicuous at each successive moult, so that this case
partly opposes and partly supports the rule. With the English Carrier
and Pouter pigeon the full development of the wattle and the crop occurs
rather late in life, and these characters, conformably with our rule,
are transmitted in full perfection to the males alone. The following
cases perhaps come within the class previously alluded to, in which the
two sexes have varied in the same manner at a rather late period of
life, and have consequently transferred their new characters to both
sexes at a corresponding late period; and if so, such cases are not
opposed to our rule. Thus there are sub-breeds of the pigeon, described
by Neumeister,[365] both sexes of which change colour after moulting
twice or thrice, as does likewise the Almond Tumbler; nevertheless these
changes, though occurring rather late in life, are common to both sexes.
One variety of the Canary-bird, namely the London Prize, offers a nearly
analogous case.

With the breeds of the Fowl the inheritance of various characters by one
sex or by both sexes, seems generally determined by the period at which
such characters are developed. Thus in all the many breeds in which the
adult male differs greatly in colour from the female and from the adult
male parent-species, he differs from the young male, so that the newly
acquired characters must have appeared at a rather late period of life.
On the other hand with most of the breeds in which the two sexes
resemble each other, the young are coloured in nearly the same manner as
their parents, and this renders it probable that their colours first
appeared early in life. We have instances of this fact in all black and
white breeds, in which the young and old of both sexes are alike; nor
can it be maintained that there is something peculiar in a black or
white plumage, leading to its transference to both sexes; for the males
alone of many natural species are either black or white, the females
being very differently coloured. With the so-called Cuckoo sub-breeds of
the fowl, in which the feathers are transversely pencilled with dark
stripes, both sexes and the chickens are coloured in nearly the same
manner. The laced plumage of the Sebright bantam is the same in both
sexes, and in the chickens the feathers are tipped with black, which
makes a near approach to lacing. Spangled Hamburghs, however, offer a
partial exception, for the two sexes, though not quite alike, resemble
each other more closely than do the sexes of the aboriginal
parent-species, yet they acquire their characteristic plumage late in
life, for the chickens are distinctly pencilled. Turning to other
characters besides colour: the males alone of the wild parent-species
and of most domestic breeds possess a fairly well developed comb, but in
the young of the Spanish fowl it is largely developed at a very early
age, and apparently in consequence of this it is of unusual size in the
adult females. In the Game breeds pugnacity is developed at a
wonderfully early age, of which curious proofs could be given; and this
character is transmitted to both sexes, so that the hens, from their
extreme pugnacity, are now generally exhibited in separate pens. With
the Polish breeds the bony protuberance of the skull which supports the
crest is partially developed even before the chickens are hatched, and
the crest itself soon begins to grow, though at first feebly;[366] and
in this breed a great bony protuberance and an immense crest
characterise the adults of both sexes.

Finally, from what we have now seen of the relation which exists in many
natural species and domesticated races, between the period of the
development of their characters and the manner of their
transmission—for example the striking fact of the early growth of the
horns in the reindeer, in which both sexes have horns, in comparison
with their much later growth in the other species in which the male
alone bears horns—we may conclude that one cause, though not the sole
cause, of characters being exclusively inherited by one sex, is their
development at a late age. And secondly, that one, though apparently a
less efficient, cause of characters being inherited by both sexes is
their development at an early age, whilst the sexes differ but little in
constitution. It appears, however, that some difference must exist
between the sexes even during an early embryonic period, for characters
developed at this age not rarely become attached to one sex.

_Summary and concluding remarks._—From the foregoing discussion on the
various laws of inheritance, we learn that characters often or even
generally tend to become developed in the same sex, at the same age, and
periodically at the same season of the year, in which they first
appeared in the parents. But these laws, from unknown causes, are very
liable to change. Hence the successive steps in the modification of a
species might readily be transmitted in different ways; some of the
steps being transmitted to one sex, and some to both; some to the
offspring at one age, and some at all ages. Not only are the laws of
inheritance extremely complex, but so are the causes which induce and
govern variability. The variations thus caused are preserved and
accumulated by sexual selection, which is in itself an extremely complex
affair, depending, as it does, on ardour in love, courage, and the
rivalry of the males, and on the powers of perception, taste, and will
of the female. Sexual selection will also be dominated by natural
selection for the general welfare of the species. Hence the manner in
which the individuals of either sex or of both sexes are affected
through sexual selection cannot fail to be complex in the highest

When variations occur late in life in one sex, and are transmitted to
the same sex at the same age, the other sex and the young are
necessarily left unmodified. When they occur late in life, but are
transmitted to both sexes at the same age, the young alone are left
unmodified. Variations, however, may occur at any period of life in one
sex or in both, and be transmitted to both sexes at all ages, and then
all the individuals of the species will be similarly modified. In the
following chapters it will be seen that all these cases frequently occur
under nature.

Sexual selection can never act on any animal whilst young, before the
age for reproduction has arrived. From the great eagerness of the male
it has generally acted on this sex and not on the females. The males
have thus become provided with weapons for fighting with their rivals,
or with organs for discovering and securely holding the female, or for
exciting and charming her. When the sexes differ in these respects, it
is also, as we have seen, an extremely general law that the adult male
differs more or less from the young male; and we may conclude from this
fact that the successive variations, by which the adult male became
modified, cannot have occurred much before the age for reproduction. How
then are we to account for this general and remarkable coincidence
between the period of variability and that of sexual selection,—
principles which are quite independent of each other? I
think we can see the cause: it is not that the males have never varied
at an early age, but that such variations have commonly been lost,
whilst those occurring at a later age have been preserved.

All animals produce more offspring than can survive to maturity; and we
have every reason to believe that death falls heavily on the weak and
inexperienced young. If then a certain proportion of the offspring were
to vary at birth or soon afterwards, in some manner which at this age
was of no service to them, the chance of the preservation of such
variations would be small. We have good evidence under domestication how
soon variations of all kinds are lost, if not selected. But variations
which occurred at or near maturity, and which were of immediate service
to either sex, would probably be preserved; as would similar variations
occurring at an earlier period in any individuals which happened to
survive. As this principle has an important bearing on sexual selection,
it may be advisable to give an imaginary illustration. We will take a
pair of animals, neither very fertile nor the reverse, and assume that
after arriving at maturity they live on an average for five years,
producing each year five young. They would thus produce 25 offspring;
and it would not, I think, be an unfair estimate to assume that 18 or 20
out of the 25 would perish before maturity, whilst still young and
inexperienced; the remaining seven or five sufficing to keep up the
stock of mature individuals. If so, we can see that variations which
occurred during youth, for instance in brightness, and which were not of
the least service to the young, would run a good chance of being utterly
lost. Whilst similar variations, which occurring at or near maturity in
the comparatively few individuals surviving to this age, and which
immediately gave an advantage to certain males, by rendering them more
attractive to the females, would be likely to be preserved. No doubt
some of the variations in brightness which occurred at an earlier age
would by chance be preserved, and eventually give to the male the same
advantage as those which appeared later; and this will account for the
young males commonly partaking to a certain extent (as may be observed
with many birds) of the bright colours of their adult male parents. If
only a few of the successive variations in brightness were to occur at a
late age, the adult male would be only a little brighter than the young
male; and such cases are common.

In this illustration I have assumed that the young varied in a manner
which was of no service to them; but many characters proper to the adult
male would be actually injurious to the young,—as bright colours from
making them conspicuous, or horns of large size from expending much
vital force. Such variations in the young would promptly be eliminated
through natural selection. With the adult and experienced males, on the
other hand, the advantage thus derived in their rivalry with other males
would often more than counterbalance exposure to some degree of danger.
Thus we can understand how it is that variations which must originally
have appeared rather late in life have alone or in chief part been
preserved for the development of secondary sexual characters; and the
remarkable coincidence between the periods of variability and of sexual
selection is intelligible.

As variations which give to the male an advantage in lighting with other
males, or in finding, securing, or charming the female, would be of no
use to the female, they will not have been preserved in this sex either
during youth or maturity. Consequently such variations would be
extremely liable to be lost; and the female, as far as these characters
are concerned, would be left unmodified, excepting in so far as she may
have received them by transference from the male. No doubt if the female
varied and transferred serviceable characters to her male offspring,
these would be favoured through sexual selection; and then both sexes
would thus far be modified in the same manner. But I shall hereafter
have to recur to these more intricate contingencies.

In the following chapters, I shall treat of the secondary sexual
characters in animals of all classes, and shall endeavour in each case
to apply the principles explained in the present chapter. The lowest
classes will detain us for a very short time, but the higher animals,
especially birds, must be treated at considerable length. It should be
borne in mind that for reasons already assigned, I intend to give only a
few illustrative instances of the innumerable structures by the aid of
which the male finds the female, or, when found, holds her. On the other
hand, all structures and instincts by which the male conquers other
males, and by which he allures or excites the female, will be fully
discussed, as these are in many ways the most interesting.

_Supplement on the proportional numbers of the two sexes in animals
belonging to various classes._

As no one, as far as I can discover, has paid attention to the relative
numbers of the two sexes throughout the animal kingdom, I will here give
such materials as I have been able to collect, although they are
extremely imperfect. They consist in only a few instances of actual
enumeration, and the numbers are not very large. As the proportions are
known with certainty on a large scale in the case of man alone, I will
first give them, as a standard of comparison.

_Man._—In England during ten years (from 1857 to 1866) 707,120 children
on an annual average have been born alive, in the proportion of 104.5
males to 100 females. But in 1857 the male births throughout England
were as 105.2, and in 1865 as 104.0 to 100. Looking to separate
districts, in Buckinghamshire (where on an average 5000 children are
annually born) the _mean_ proportion of male to female births, during
the whole period of the above ten years, was as 102.8 to 100; whilst in
N. Wales (where the average annual births are 12,873) it was as high as
106.2 to 100. Taking a still smaller district, viz., Rutlandshire (where
the annual births average only 739), in 1864 the male births were as
114.6, and in 1862 as 97.0 to 100; but even in this small district the
average of the 7385 births during the whole ten years was as 104.5 to
100; that is in the same ratio as throughout England.[367] The
proportions are sometimes slightly disturbed by unknown causes; thus
Prof. Faye states “that in some districts of Norway there has been
during a decennial period a steady deficiency of boys, whilst in others
the opposite condition has existed.” In France during forty-four years
the male to the female births have been as 106.2 to 100; but during this
period it has occurred five times in one department, and six times in
another, that the female births have exceeded the males. In Russia the
average proportion is as high as 108.9 to 100.[368] It is a singular
fact that with Jews the proportion of male births is decidedly larger
than with Christians: thus in Prussia the proportion is as 113, in
Breslau as 114, and in Livonia as 120 to 100; the Christian births in
these countries being the same as usual, for instance, in Livonia as 104
to 100.[369] It is a still more singular fact that in different nations,
under different conditions and climates, in Naples, Prussia, Westphalia,
France and England, the excess of male over female births is less when
they are illegitimate than when legitimate.[370]

In various parts of Europe, according to Prof. Faye and other authors,
“a still greater preponderance of males would be met with, if death
struck both sexes in equal proportion in the womb and during birth. But
the fact is, that for every 100 still-born females, we have in several
countries from 134.6 to 144.9 still-born males.” Moreover during the
first four or five years of life more male children die than females;
“for example in England, during the first year, 126 boys die
for every 100 girls,—a proportion which in France is still more
unfavourable.”[371] As a consequence of this excess in the death-rate of
male children, and of the exposure of men when adult to various dangers,
and of their tendency to emigrate, the females in all old-settled
countries, where statistical records have been kept,[372] are found to
preponderate considerably over the males.

It has often been supposed that the relative ages of the parents
determine the sex of the offspring; and Prof. Leuckart[373] has advanced
what he considers sufficient evidence, with respect to man and certain
domesticated animals, to shew that this is one important factor in the
result. So again the period of impregnation has been thought to be the
efficient cause; but recent observations discountenance this belief.
Again, with mankind polygamy has been supposed to lead to the birth of a
greater proportion of female infants; but Dr. J. Campbell[374] carefully
attended to this subject in the harems of Siam, and he concludes that
the proportion of male to female births is the same as from monogamous
unions. Hardly any animal has been rendered so highly polygamous as our
English race-horses, and we shall immediately see that their male and
female offspring are almost exactly equal in number.

  _Horses._—Mr. Tegetmeier has been so kind as to tabulate for
  me from the ‘Racing Calendar’ the births of race-horses during
  a period of twenty-one years, viz. from 1846 to 1867; 1849
  being omitted, as no returns were that year published. The
  total births have been 25,560,[375] consisting of 12,763 males
  and 12,797 females, or in the proportion of 99.7 males to 100
  females. As these numbers are tolerably large, and as they are
  drawn from all parts of England, during several years, we may
  with much confidence conclude that with the domestic horse, or
  at least with the race-horse, the two sexes are produced in
  almost equal numbers. The fluctuations in the proportions
  during successive years are closely like those which occur with
  mankind, when a small and thinly-populated area is considered:
  thus in 1856 the male horses were as 107.1, and in 1867 as only
  92.6 to 100 females. In the tabulated returns the proportions
  vary in cycles, for the males exceeded the females during six
  successive years; and the females exceeded the males during two
  periods each of four years: this, however, may be accidental;
  at least I can detect nothing of the kind with man in the
  decennial table in the Registrar’s Report for 1866. I may add
  that certain, mares, and this holds good with certain cows and
  with women, tend to produce more of one sex than of the other;
  Mr. Wright of Yeldersley House, informs me that one of his Arab
  mares, though put seven times to different horses, produced
  seven fillies.

  _Dogs._—During a period of twelve years, from 1857 to 1868,
  the births of a large number of greyhounds, throughout England,
  have been sent to the ‘Field’ newspaper; and I am again
  indebted to Mr. Tegetmeier for carefully tabulating the
  results. The recorded, births have been 6878, consisting of
  3605 males and 3273 females, that is, in the proportion of
  110.1 males to 100 females. The greatest fluctuations occurred
  in 1864, when the proportion was as 95.3 males, and in 1867, as
  116.3 males to 100 females. The above average proportion of
  110.1 to 100 is probably nearly correct in the case of the
  greyhound, but whether it would hold with other domesticated
  breeds is in some degree doubtful. Mr. Cupples has enquired
  from several great breeders of dogs, and finds that all without
  exception believe that females are produced in excess; he
  suggests that this belief may have arisen from females being
  less valued and the consequent disappointment producing a
  stronger impression on the mind.

  _Sheep._—The sexes of sheep are not ascertained by
  agriculturists until several months after birth, at the period
  when the males are castrated; so that the following returns do
  not give the proportions at birth. Moreover, I find that
  several great breeders in Scotland, who annually raise some
  thousand sheep, are firmly convinced that a larger proportion
  of males than of females die during the first one or two years;
  therefore the proportion of males would be somewhat greater at
  birth than at the age of castration. This is a remarkable
  coincidence with what occurs, as we have seen, with mankind,
  and both cases probably depend on some common cause. I have
  received returns from four gentlemen in England who have bred
  lowland sheep, chiefly Leicesters, during the last ten or
  sixteen years; they amount altogether to 8965 births,
  consisting of 4407 males and 4558 females; that is in the
  proportion of 96.7 males to 100 females. With respect to
  Cheviot and black-faced sheep bred in Scotland, I have received
  returns from six breeders, two of them on a large scale,
  chiefly for the years 1867-1869, but some of the returns
  extending back to 1862. The total number recorded amounts to
  50,685, consisting of 25,071 males and 25,614 females, or in
  the proportion of 97.9 males to 100 females. If we take the
  English and Scotch returns together, the total number amounts
  to 59,650, consisting of 29,478 males and 30,172 females, or
  as 97·7 to 100. So that with sheep at the age of castration the
  females are certainly in excess of the males; but whether this
  would hold good at birth is doubtful, owing to the greater
  liability in the males to early death.[376]

  Of _Cattle_ I have received returns from nine gentlemen of 982
  births, too few to be trusted; these consisted of 477
  bull-calves and 505 cow-calves; _i.e._ in the proportion of
  94·4 males to 100 females. The Rev. W. D. Fox informs me that
  in 1867 out of 34 calves born on a farm in Derbyshire only one
  was a bull. Mr. Harrison Weir writes to me that he has enquired
  from several breeders of _Pigs_, and most of them estimate the
  male to the female births as about 7 to 6. This same gentleman
  has bred _Rabbits_ for many years, and has noticed that a far
  greater number of bucks are produced than does.

  Of mammalia in a state of nature I have been able to learn very
  little. In regard to the common rat, I have received
  conflicting statements. Mr. R. Elliot of Laighwood, informs me
  that a rat-catcher assured him that he had always found the
  males in great excess, even with the young in the nest. In
  consequence of this, Mr. Elliot himself subsequently examined
  some hundred old ones, and found the statement true. Mr. F.
  Buckland has bred a large number of white rats, and he also
  believes that the males greatly exceed the females. In regard
  to Moles, it is said that “the males are much more numerous
  than the females;”[377] and as the catching of these animals is
  a special occupation, the statement may perhaps be trusted. Sir
  A. Smith, in describing an antelope of S. Africa[378] (_Kobus
  ellipsiprymnus_), remarks, that in the herds of this and other
  species, the males are few in number compared with the females:
  the natives believe that they are born in this proportion;
  others believe that the younger males are expelled from the
  herds, and Sir A. Smith says, that though he has himself never
  seen herds consisting of young males alone, others affirm that
  this does occur. It appears probable that the young males when
  expelled from the herd, would be likely to fell a prey to the
  many beasts of prey of the country.


  With respect to the _Fowl_, I have received only one account,
  namely, that out of 1001 chickens of a highly-bred stock of
  Cochins, reared during eight years by Mr. Stretch, 487 proved
  males and 514 females: _i.e._ as 94.7 to 100. In regard to
  domestic pigeons there is good evidence that the males are
  produced in excess, or that their lives are longer; for these
  birds invariably pair, and single males, as Mr. Tegetmeier
  informs me, can always be purchased cheaper than females.
  Usually the two birds reared from the two eggs laid in the same
  nest consist of a male and female; but Mr. Harrison Weir, who
  has been so large a breeder, says that he has often bred two
  cocks from the same nest, and seldom two hens; moreover the hen
  is generally the weaker of the two, and more liable to perish.

  With respect to birds in a state of nature, Mr. Gould and
  others[379] are convinced that the males are generally the more
  numerous; and as the young males of many species resemble the
  females, the latter would naturally appear to be the most
  numerous. Large numbers of pheasants are reared by Mr. Baker of
  Leadenhall from eggs laid by wild birds, and he informs Mr.
  Jenner Weir that four or five males to one female are generally
  produced. An experienced observer remarks[380] that in
  Scandinavia the broods of the capercailzie and black-cock
  contain more males than females; and that with the Dal-ripa (a
  kind of ptarmigan) more males than females attend the _leks_ or
  places of courtship; but this latter circumstance is accounted
  for by some observers by a greater number of hen birds being
  killed by vermin. From various facts given by White of
  Selbourne,[381] it seems clear that the males of the partridge
  must be in considerable excess in the south of England; and I
  have been assured that this is the case in Scotland. Mr. Weir
  on enquiring from the dealers who receive at certain seasons
  large numbers of ruffs (_Machetes pugnax_) was told that the
  males are much the most numerous. This same naturalist has also
  enquired for me from the bird-catchers, who annually catch an
  astonishing number of various small species alive for the
  London market, and he was unhesitatingly answered by an old and
  trustworthy man, that with the chaffinch the males are in large
  excess; he thought as high as 2 males to 1 female, or at least
  as high as 5 to 3.[382] The males of the blackbird, he likewise
  maintained, were by far the most numerous, whether caught by
  traps or by netting at night. These statements may apparently
  be trusted, because the same man said that the sexes are about
  equal with the lark, the twite (_Linaria montana_), and
  goldfinch. On the other hand he is certain that with the common
  linnet, the females preponderate greatly, but unequally during
  different years; during some years he has found the females to
  the males as four to one. It should, however, be borne in mind,
  that the chief season for catching birds does not begin till
  September, so that with some species partial migrations may
  have begun, and the flocks at this period often consist of hens
  alone. Mr. Salvin paid particular attention to the sexes of the
  humming-birds in Central America, and he is convinced that with
  most of the species the males are in excess; thus one year he
  procured 204 specimens belonging to ten species, and these
  consisted of 166 males and of 38 females. With two other
  species the females were in excess: but the proportions
  apparently vary either during different seasons or in different
  localities; for on one occasion the males of _Campylopterus
  hemileucurus_ were to the females as five to two, and on
  another occasion[383] in exactly the reversed ratio. As bearing
  on this latter point, I may add, that Mr. Powys found in Corfu
  and Epirus the sexes of the chaffinch keeping apart, and “the
  females by far the most numerous;” whilst in Palestine Mr.
  Tristram found “the male flocks appearing greatly to exceed the
  female in number.”[384] So again with the _Quiscalus major_,
  Mr. G. Taylor[385] says, that in Florida there were “very few
  females in proportion to the males,” whilst in Honduras the
  proportion was the other way, the species there having the
  character of a polygamist.


  With Fish the proportional numbers of the sexes can be
  ascertained only by catching them in the adult or nearly adult
  state; and there are many difficulties in arriving at any just
  conclusion.[386] Infertile females might readily be mistaken
  for males, as Dr. Günther has remarked to me in regard to
  trout. With some species the males are believed to die soon
  after fertilising the ova. With many species the males are of
  much smaller size than the females, so that a large number of
  males would escape from the same net by which the females were
  caught. M. Carbonnier,[387] who has especially attended to the
  natural history of the pike (_Esox lucius_) states that many
  males, owing to their small size, are devoured by the larger
  females; and he believes that the males of almost all fish are
  exposed from the same cause to greater danger than the females.
  Nevertheless in the few cases in which the proportional numbers
  have been actually observed, the males appear to be largely in
  excess. Thus Mr. R. Buist, the superintendent of the
  Stormontfield experiments, says that in 1865, out of 70 salmon
  first landed for the purpose of obtaining the ova, upwards of
  60 were males. In 1867 he again “calls attention to the vast
  disproportion of the males to the females. We had at the outset
  at least ten males to one female.” Afterwards sufficient
  females for obtaining ova were procured. He adds, “from the
  great proportion of the males, they are constantly fighting and
  tearing each other on the spawning-beds.”[388] This
  disproportion, no doubt, can be accounted for in part, but
  whether wholly is very doubtful, by the males ascending the
  rivers before the females. Mr. F. Buckland remarks in regard to
  trout, that “it is a curious fact that the males preponderate
  very largely in number over the females. It _invariably_
  happens that when the first rush of fish is made to the net,
  there will be at least seven or eight males to one female found
  captive. I cannot quite account for this; either the males are
  more numerous than the females, or the latter seek safety by
  concealment rather than flight.” He then adds, that by
  carefully searching the banks, sufficient females for obtaining
  ova can be found.[389] Mr. H. Lee informs me that out of 212
  trout, taken for this purpose in Lord Portsmouth’s park, 150
  were males and 62 females.

  With the Cyprinidæ the males likewise seem to be in excess; but
  several members of this Family, viz., the carp, tench, bream
  and minnow, appear regularly to follow the practice, rare in
  the animal kingdom, of polyandry; for the female whilst
  spawning is always attended by two males, one on each side, and
  in the case of the bream by three or four males. This fact is
  so well known, that it is always recommended to stock a pond
  with two male tenches to one female, or at least with three
  males to two females. With the minnow, an excellent observer
  states, that on the spawning-beds the males are ten times as
  numerous as the females; when a female comes amongst the males,
  “she is immediately pressed closely by a male on each side; and
  when they have been in that situation for a time, are
  superseded by other two males.”[390]


  In this class, the Lepidoptera alone afford the means of
  judging of the proportional numbers of the sexes; for they have
  been collected with special care by many good observers, and
  have been largely bred from the egg or caterpillar state. I had
  hoped that some breeders of silk-moths might have kept an exact
  record, but after writing to France and Italy, and consulting
  various treatises, I cannot find that this has ever been done.
  The general opinion appears to be that the sexes are nearly
  equal, but in Italy as I hear from Professor Canestrini, many
  breeders are convinced that the females are produced in excess.
  The same naturalist, however, informs me, that in the two
  yearly broods of the Ailanthus silk-moth (_Bombyx cynthia_),
  the males greatly preponderate in the first, whilst in the
  second the two sexes are nearly equal, or the females rather in

  In regard to Butterflies in a state of nature, several
  observers have been much struck by the apparently enormous
  preponderance of the males.[391] Thus Mr. Bates,[392] in
  speaking of the species, no less than about a hundred in
  number, which inhabit the Upper Amazons, says that the males
  are much more numerous than the females, even in the proportion
  of a hundred to one. In North America, Edwards, who had great
  experience, estimates in the genus Papilio the males to the
  females as four to one; and Mr. Walsh, who informed me of this
  statement, says that with _P. turnus_ this is certainly the
  case. In South Africa, Mr. R. Trimen found the males in excess
  in 19 species;[393] and in one of these, which swarms in open
  places, he estimated the number of males as fifty to one
  female. With another species, in which the males are numerous
  in certain localities, he collected during seven years only
  five females. In the island of Bourbon, M. Maillard states that
  the males of one species of Papilio are twenty times as
  numerous as the females.[394] Mr. Trimen informs me that as far
  as he has himself seen, or heard from others, it is rare for
  the females of any butterfly to exceed in number the males; but
  this is perhaps the case with three South African species. Mr.
  Wallace[395] states that the females of _Ornithoptera
  crœsus_, in the Malay archipelago, are more common and more
  easily caught than the males; but this is a rare butterfly. I
  may here add, that in Hyperythra, a genus of moths, Guenée
  says, that from four to five females are sent in collections
  from India for one male.

  When this subject of the proportional numbers of the sexes of
  insects was brought before the Entomological Society,[396] it
  was generally admitted that the males of most Lepidoptera, in
  the adult or imago state, are caught in greater numbers than
  the females; but this fact was attributed by various observers
  to the more retiring habits of the females, and to the males
  emerging earlier from the cocoon. This latter circumstance is
  well known to occur with most Lepidoptera, as well as with
  other insects. So that, as M. Personnat remarks, the males of
  the domesticated _Bombyx yamamai_, are lost at the beginning of
  the season, and the females at the end, from the want of
  mates.[397] I cannot however persuade myself that these causes
  suffice to explain the great excess of males in the cases,
  above given, of butterflies which are extremely common in their
  native countries. Mr. Stainton, who has paid such close
  attention during many years to the smaller moths, informs me
  that when he collected them in the imago state, he thought that
  the males were ten times as numerous as the females, but that
  since he has reared them on a large scale from the caterpillar
  state, he is convinced that the females are the most numerous.
  Several entomologists concur in this view. Mr. Doubleday,
  however, and some others, take an opposite view, and are
  convinced that they have reared from the egg and caterpillar
  states a larger proportion of males than of females.

  Besides the more active habits of the males, their earlier
  emergence from the cocoon, and their frequenting in some cases
  more open stations, other causes may be assigned for an
  apparent or real difference in the proportional numbers of the
  sexes of Lepidoptera, when captured in the imago state, and
  when reared from the egg or caterpillar state. It is believed
  by many breeders in Italy, as I hear from Professor Canestrini,
  that the female caterpillar of the silk-moth suffers more from
  the recent disease than the male; and Dr. Staudinger informs me
  that in rearing Lepidoptera more females die in the cocoon than
  males. With many species the female caterpillar is larger than
  the male, and a collector would naturally choose the finest
  specimens, and thus unintentionally collect a larger number of
  females. Three collectors have told me that this was their
  practice; but Dr. Wallace is sure that most collectors take all
  the specimens which they can find of the rarer kinds, which
  alone are worth the trouble of rearing. Birds when surrounded
  by caterpillars would probably devour the largest; and
  Professor Canestrini informs me that in Italy some breeders
  believe, though on insufficient evidence, that in the first
  brood of the Ailanthus silk-moth, the wasps destroy a larger
  number of the female than of the male caterpillars. Dr. Wallace
  further remarks that female caterpillars, from being larger
  than the males, require more time for their development and
  consume more food and moisture; and thus they would be exposed
  during a longer time to danger from ichneumons, birds, &c., and
  in times of scarcity would perish in greater numbers. Hence it
  appears quite possible that, in a state of nature, fewer female
  Lepidoptera may reach maturity than males; and for our special
  object we are concerned with the numbers at maturity, when the
  sexes are ready to propagate their kind.

  The manner in which the males of certain moths congregate in
  extraordinary numbers round a single female, apparently
  indicates a great excess of males, though this fact may perhaps
  be accounted for by the earlier emergence of the males from
  their cocoons. Mr. Stainton informs me that from twelve to
  twenty males may often be seen congregated round a female
  _Elachista rufocinerea_. It is well known that if a virgin
  _Lasiocampa quercus_ or _Saturnia carpini_ be exposed in a
  cage, vast numbers of males collect round her, and if confined
  in a room will even come down the chimney to her. Mr.
  Doubleday believes that he has seen from fifty to a hundred
  males of both these species attracted in the course of a single
  day by a female under confinement. Mr. Trimen exposed in the
  Isle of Wight a box in which a female of the Lasiocampa had
  been confined on the previous day, and five males soon
  endeavoured to gain admittance. M. Verreaux, in Australia,
  having placed the female of a small Bombyx in a box in his
  pocket, was followed by a crowd of males, so that about 200
  entered the house with him.[398]

  Mr. Doubleday has called my attention to Dr. Staudinger’s[399]
  list of Lepidoptera, which gives the prices of the males and
  females of 300 species or well-marked varieties of
  (Rhopalocera) butterflies. The prices for both sexes of the
  very common species are of course the same; but with 114 of the
  rarer species they differ; the males being in all cases,
  excepting one, the cheapest. On an average of the prices of the
  113 species, the price of the male to that of the female is as
  100 to 149; and this apparently indicates that inversely the
  males exceed the females in number in the same proportion.
  About 2000 species or varieties of moths (Heterocera) are
  catalogued, those with wingless females being here excluded on
  account of the difference in habits of the two sexes: of these
  2000 species, 141 differ in price according to sex, the males
  of 130 being cheaper, and the males of only 11 being dearer
  than the females. The average price of the males of the 130
  species, to that of the females, is as 100 to 143. With respect
  to the butterflies in this priced list, Mr. Doubleday thinks
  (and no man in England has had more experience), that there is
  nothing in the habits of the species which can account for the
  difference in the prices of the two sexes, and that it can be
  accounted for only by an excess in the numbers of the males.
  But I am bound to add that Dr. Staudinger himself, as he
  informs me, is of a different opinion. He thinks that the less
  active habits of the females and the earlier emergence of the
  males will account for his collectors securing a larger number
  of males than of females, and consequently for the lower prices
  of the former With respect to specimens reared from the
  caterpillar-state, Dr. Staudinger believes, as previously
  stated, that a greater number of females than of males die
  under confinement in the cocoons. He adds that with certain
  species one sex seems to preponderate over the other during
  certain years.

  Of direct observations on the sexes of Lepidoptera, reared
  either from eggs or caterpillars, I have received only the few
  following cases:—

                                                    Males. | Females.
  The Rev. J. Hellins[400] of Exeter reared, during        |
    1868, imagos of 73 species, which consisted of   153   |   137
  Mr. Albert Jones of Eltham reared, during 1868,          |
    imagos of 9 species, which, consisted of         159   |   126
  During 1869 he reared imagos from 4 species,             |
    consisting of                                    114   |   112
  Mr. Buckler of Emsworth, Hants, during 1869,             |
    reared imagos from 74 species, consisting of     180   |   169
  Dr. Wallace of Colchester reared from one brood          |
    of Bombyx cynthia                                 52   |    48
  Dr. Wallace raised, from cocoons of Bombyx               |
    Pernyi sent from China, during 1869              224   |   123
  Dr. Wallace raised, during 1868 and 1869,                |
    from two lots of cocoons of Bombyx yamamai        52   |    46
                        Total                        934   |   761

  So that in these eight lots of cocoons and eggs, males were
  produced in excess. Taken together the proportion of males is
  as 122.7 to 100 females. But the numbers are hardly large
  enough to be trustworthy.

  On the whole, from the above various sources of evidence, all
  pointing to the same direction, I infer that with most species
  of Lepidoptera, the males in the imago state generally exceed
  the females in number, whatever the proportions may be at their
  first emergence from the egg.

  With reference to the other Orders of insects, I have been able
  to collect very little reliable information. With the
  stag-beetle (_Lucanus cervus_) “the males appear to be much
  more numerous than the females;” but when, as Cornelius
  remarked during 1867, an unusual number of these beetles
  appeared in one part of Germany, the females appeared to exceed
  the males as six so one. With one of the Elateridæ, the males
  are said to be much more numerous than the females, and “two or
  three are often found united with one female;”[401] so that here
  polyandry seems to prevail. With Siagonium (Staphylinidæ), in
  which the males are furnished with horns, “the females are far
  more numerous than the opposite sex.” Mr. Janson stated at the
  Entomological Society that the females of the bark-feeding
  _Tomicus villosus_ are so common as to be a plague, whilst the
  males are so rare as to be hardly known. In other Orders, from
  unknown causes, but apparently in some instances owing to
  parthenogenesis, the males of certain species have never been
  discovered or are excessively rare, as with several of the
  Cynipidæ.[402] In all the gall-making Cynipidæ known to Mr.
  Walsh, the females are four or five times as numerous as the
  males; and so it is, as he informs me, with the gall-making
  Cecidomyiiæ (Diptera). With some common species of Saw-flies
  (Tenthredinæ) Mr. F. Smith has reared hundreds of specimens
  from larvæ of all sizes, but has never reared a single male: on
  the other hand Curtis says,[403] that with certain species
  (Athalia), bred by him, the males to the females were as six to
  one; whilst exactly the reverse occurred with the mature
  insects of the same species caught in the fields. With the
  Neuroptera, Mr. Walsh states that in many, but by no means in
  all, the species of the Odonatous groups (Ephemerina), there is
  a great overplus of males: in the genus Hetærina, also, the
  males are generally at least four times as numerous as the
  females. In certain species in the genus Gomphus the males are
  equally numerous, whilst in two other species, the females are
  twice or thrice as numerous as the males. In some European
  species of Psocus thousands of females may be collected without
  a single male, whilst with other species of the same genus both
  sexes are common.[404] In England, Mr. MacLachlan has captured
  hundreds of the female _Apatania muliebris_, but has never seen
  the male; and of _Boreus hyemalis_ only four or five males have
  been here seen.[405] With most of these species (excepting, as
  I have heard, with the Tenthredinæ) there is no reason to
  suppose that the females are subject to parthenogenesis; and
  thus we see how ignorant we are on the causes of the apparent
  discrepancy in the proportional numbers of the two sexes.

  In the other Classes of the Articulata I have been able to
  collect still less information. With Spiders, Mr. Blackwall,
  who has carefully attended to this class during many years,
  writes to me that the males from their more erratic habits are
  more commonly seen, and therefore appear to be the more
  numerous. This is actually the case with a few species; but he
  mentions several species in six genera, in which the females
  appear to be much more numerous than the males.[406] The small
  size of the males in comparison with the females, which is
  sometimes carried to an extreme degree, and their widely
  different appearance, may account in some instances for their
  rarity in collections.[407]

  Some of the lower Crustaceans are able to propagate their kind
  asexually, and this will account for the extreme rarity of the
  males. With some other forms (as with Tanais and Cypris) there
  is reason to believe, as Fritz Müller informs me, that the male
  is much shorter-lived than the female, which, supposing the two
  sexes to be at first equal in number, would explain the
  scarcity of the males. On the other hand this same naturalist
  has invariably taken, on the shores of Brazil, far more males
  than females of the Diastylidæ and of Cypridina; thus with a
  species in the latter genus, 63 specimens caught the same day,
  included 57 males; but he suggests that this preponderance may
  be due to some unknown difference in the habits of the two
  sexes. With one of the higher Brazilian crabs, namely a
  Gelasimus, Fritz Müller found the males to be more numerous
  than the females. The reverse seems to be the case, according
  to the large experience of Mr. C. Spence Bate, with six common
  British crabs, the names of which he has given me.

_On the Power of Natural Selection to regulate the proportional Numbers
of the Sexes, and General Fertility._—In some peculiar cases, an excess
in the number of one sex over the other might be a great advantage to a
species, as with the sterile females of social insects, or with those
animals in which more than one male is requisite to fertilise the
female, as with certain cirripedes and perhaps certain fishes. An
inequality between the sexes in these cases might have been acquired
through natural selection, but from their rarity they need not here be
further considered. In all ordinary cases an inequality would be no
advantage or disadvantage to certain individuals more than to others;
and therefore it could hardly have resulted from natural selection. We
must attribute the inequality to the direct action of those unknown
conditions, which with mankind lead to the males being born in a
somewhat larger excess in certain countries than in others, or which
cause the proportion between the sexes to differ slightly in legitimate
and illegitimate births.

Let us now take the case of a species producing from the unknown causes
just alluded to, an excess of one sex—we will say of males—these being
superfluous and useless, or nearly useless. Could the sexes be equalised
through natural selection? We may feel sure, from all characters being
variable, that certain pairs would produce a somewhat less excess of
males over females than other pairs. The former, supposing the actual
number of the offspring to remain constant, would necessarily produce
more females, and would therefore be more productive. On the doctrine of
chances a greater number of the offspring of the more productive pairs
would survive; and these would inherit a tendency to procreate fewer
males and more females. Thus a tendency towards the equalisation of the
sexes would be brought about. But our supposed species would by this
process be rendered, as just remarked, more productive; and this would
in many cases be far from an advantage; for whenever the limit to the
numbers which exist, depends, not on destruction by enemies, but on the
amount of food, increased fertility will lead to severer competition and
to most of the survivors being badly fed. In this case, if the sexes
were equalised by an increase in the number of the females, a
simultaneous decrease in the total number of the offspring would be
beneficial, or even necessary, for the existence of the species; and
this, I believe, could be effected through natural selection in the
manner hereafter to be described. The same train of reasoning is
applicable in the above, as well as in the following case, if we assume
that females instead of males are produced in excess, for such females
from not uniting with males would be superfluous and useless. So it
would be with polygamous species, if we assume the excess of females to
be inordinately great.

An excess of either sex, we will again say of the males, could, however,
apparently be eliminated through natural selection in another and
indirect manner, namely by an actual diminution of the males, without
any increase of the females, and consequently without any increase in
the productiveness of the species. From the variability of all
characters, we may feel assured that some pairs, inhabiting any
locality, would produce a rather smaller excess of superfluous males,
but an equal number of productive females. When the offspring from the
more and the less male-productive parents were all mingled together,
none would have any direct advantage over the others; but those that
produced few superfluous males would have one great indirect advantage,
namely that their ova or embryos would probably be larger and finer, or
their young better nurtured in the womb and afterwards. We see this
principle illustrated with plants; as those which bear a vast number of
seed produce small ones; whilst those which bear comparatively few
seeds, often produce large ones well-stocked with nutriment for the use
of the seedlings.[408] Hence the offspring of the parents which had
wasted least force in producing superfluous males would be the most
likely to survive, and would inherit the same tendency not to produce
superfluous males, whilst retaining their full fertility in the
production of females. So it would be with the converse case of the
female sex. Any slight excess, however, of either sex could hardly be
checked in so indirect a manner. Nor indeed has a considerable
inequality between the sexes been always prevented, as we have seen in
some of the cases given in the previous discussion. In these cases the
unknown causes which determine the sex of the embryo, and which under
certain conditions lead to the production of one sex in excess over the
other, have not been mastered by the survival of those varieties which
were subjected to the least waste of organised matter and force by the
production of superfluous individuals of either sex. Nevertheless we may
conclude that natural selection will always tend, though sometimes
inefficiently, to equalise the relative numbers of the two sexes.

Having said this much on the equalisation of the sexes, it may be well
to add a few remarks on the regulation through natural selection of the
ordinary fertility of species. Mr. Herbert Spencer has shewn in an able
discussion[409] that with all organisms a ratio exists between what he
calls individuation and genesis; whence it follows that beings which
consume much matter or force in their growth, complicated structure or
activity, or which produce ova and embryos of large size, or which
expend much energy in nurturing their young, cannot be so productive as
beings of an opposite nature. Mr. Spencer further shews that minor
differences in fertility will be regulated through natural selection.
Thus the fertility of each species will tend to increase, from the more
fertile pairs producing a larger number of offspring, and these from
their mere number will have the best chance of surviving, and will
transmit their tendency to greater fertility. The only check to a
continued augmentation of fertility in each organism seems to be either
the expenditure of more power and the greater risks run by the parents
that produce a more numerous progeny, or the contingency of very
numerous eggs and young being produced of smaller size, or less
vigorous, or subsequently not so well nurtured. To strike a balance in
any case between the disadvantages which follow from the production of a
numerous progeny, and the advantages (such as the escape of at least
some individuals from various dangers) is quite beyond our power of

When an organism has once been rendered extremely fertile, how its
fertility can be reduced through natural selection is not so clear as
how this capacity was first acquired. Yet it is obvious that if
individuals of a species, from a decrease of their natural enemies, were
habitually reared in larger numbers than could be supported, all the
members would suffer. Nevertheless the offspring from the less fertile
parents would have no direct advantage over the offspring from the more
fertile parents, when all were mingled together in the same district.
All the individuals would mutually tend to starve each other. The
offspring indeed of the less fertile parents would lie under one great
disadvantage, for from the simple fact of being produced in smaller
numbers, they would be the most liable to extermination. Indirectly,
however, they would partake of one great advantage; for under the
supposed condition of severe competition, when all were pressed for
food, it is extremely probable that those individuals which from some
variation in their constitution produced fewer eggs or young, would
produce them of greater size or vigour; and the adults reared from such
eggs or young would manifestly have the best chance of surviving, and
would inherit a tendency towards lessened fertility. The parents,
moreover, which had to nourish or provide for fewer offspring would
themselves be exposed to a less severe strain in the struggle for
existence, and would have a better chance of surviving. By these steps,
and by no others as far as I can see, natural selection under the above
conditions of severe competition for food, would lead to the formation
of a new race less fertile, but better adapted for survival, than the



  These characters absent in the lowest classes—Brilliant
  colours—Mollusca—Annelids—Crustacea, secondary sexual
  characters strongly developed; dimorphism; colour; characters
  not acquired before maturity—Spiders, sexual colours of;
  stridulation by the males—Myriapoda.

In the lowest classes the two sexes are not rarely united in the same
individual, and therefore secondary sexual characters cannot be
developed. In many cases in which the two sexes are separate, both are
permanently attached to some support, and the one cannot search or
struggle for the other. Moreover it is almost certain that these animals
have too imperfect senses and much too low mental powers to feel mutual
rivalry, or to appreciate each other’s beauty or other attractions.

Hence in these classes, such as the Protozoa, Cœlenterata,
Echinodermata, Scolecida, true secondary sexual characters do not occur;
and this fact agrees with the belief that such characters in the higher
classes have been acquired through sexual selection, which depends on
the will, desires, and choice of either sex. Nevertheless some few
apparent exceptions occur; thus, as I hear from Dr. Baird, the males of
certain Entozoa, or internal parasitic worms, differ slightly in colour
from the females; but we have no reason to suppose that such differences
have been augmented through sexual selection.

Many of the lower animals, whether hermaphrodites or with the sexes
separate, are ornamented with the most brilliant tints, or are shaded
and striped in an elegant manner. This is the case with many corals and
sea-anemonies (Actiniæ), with some jelly-fish (Medusæ, Porpita, &c.),
with some Planariæ, Ascidians, numerous Star-fishes, Echini, &c.; but we
may conclude from the reasons already indicated, namely the union of the
two sexes in some of these animals, the permanently affixed condition of
others, and the low mental powers of all, that such colours do not serve
as a sexual attraction, and have not been acquired through sexual
selection. With the higher animals the case is very different; for with
them when one sex is much more brilliantly or conspicuously coloured
than the other, and there is no difference in the habits of the two
sexes which will account for this difference, we have reason to believe
in the influence of sexual selection; and this belief is strongly
confirmed when the more ornamented individuals, which are almost always
the males, display their attractions before the other sex. We may also
extend this conclusion to both sexes, when coloured alike, if their
colours are plainly analogous to those of one sex alone in certain other
species of the same group.

How, then, are we to account for the beautiful or even gorgeous colours
of many animals in the lowest classes? It appears very doubtful whether
such colours usually serve as a protection; but we are extremely liable
to err in regard to characters of all kinds in relation to protection,
as will be admitted by every one who has read Mr. Wallace’s excellent
essay on this subject. It would not, for instance, at first occur to any
one that the perfect transparency of the Medusæ, or jelly-fishes, was of
the highest service to them as a protection; but when we are reminded
by Häckel that not only the medusæ but many floating mollusca,
crustaceans, and even small oceanic fishes partake of this same
glass-like structure, we can hardly doubt that they thus escape the
notice of pelagic birds and other enemies.

Notwithstanding our ignorance how far colour in many cases serves as a
protection, the most probable view in regard to the splendid tints of
many of the lowest animals seems to be that their colours are the direct
result either of the chemical nature or the minute structure of their
tissues, independently of any benefit thus derived. Hardly any colour is
finer than that of arterial blood; but there is no reason to suppose
that the colour of the blood is in itself any advantage; and though it
adds to the beauty of the maiden’s cheek, no one will pretend that it
has been acquired for this purpose. So again with many animals,
especially the lower ones, the bile is richly coloured; thus the extreme
beauty of the Eolidæ (naked sea-slugs) is chiefly due, as I am informed
by Mr. Hancock, to the biliary glands seen through the translucent
integuments; this beauty being probably of no service to these animals.
The tints of the decaying leaves in an American forest are described by
every one as gorgeous; yet no one supposes that these tints are of the
least advantage to the trees. Bearing in mind how many substances
closely analogous to natural organic compounds have been recently formed
by chemists, and which exhibit the most splendid colours, it would have
been a strange fact if substances similarly coloured had not often
originated, independently of any useful end being thus gained, in the
complex laboratory of living organisms.

_The sub-kingdom of the Mollusca._—Throughout this great division
(taken in its largest acceptation) of the animal kingdom, secondary
sexual characters, such as we are here considering, never, as far as I
can discover, occur. Nor could they be expected in the three lowest
classes, namely in the Ascidians, Polyzoa, and Brachiopods (constituting
the Molluscoida of Huxley), for most of these animals are permanently
affixed to a support or have their sexes united in the same individual.
In the Lamellibranchiata, or bivalve shells, hermaphroditism is not
rare. In the next higher class of the Gasteropoda, or marine univalve
shells, the sexes are either united or separate. But in this latter case
the males never possess special organs for finding, securing, or
charming the females, or for fighting with other males. The sole
external difference between the sexes consists, as I am informed by Mr.
Gwyn Jeffreys, in the shell sometimes differing a little in form; for
instance, the shell of the male periwinkle (_Littorina littorea_) is
narrower and has a more elongated spire than that of the female. But
differences of this nature, it may be presumed, are directly connected
with the act of reproduction or with the development of the ova.

The Gasteropoda, though capable of locomotion and furnished with
imperfect eyes, do not appear to be endowed with sufficient mental
powers for the members of the same sex to struggle together in rivalry,
and thus to acquire secondary sexual characters. Nevertheless with the
pulmoniferous gasteropods, or land-snails, the pairing is preceded by
courtship; for these animals, though hermaphrodites, are compelled by
their structure to pair together. Agassiz remarks,[410] “Quiconque a eu
l’occasion d’observer les amours des limaçons, ne saurait mettre en
doute la séduction déployée dans les mouvements et les allures qui
préparent et accomplissent le double embrassement de ces
hermaphrodites.” These animals appear also susceptible of some degree of
permanent attachment: an accurate observer, Mr. Lonsdale, informs me
that he placed a pair of land-shells (_Helix pomatia_), one of which was
weakly, into a small and ill-provided garden. After a short time the
strong and healthy individual disappeared, and was traced by its track
of slime over a wall into an adjoining well-stocked garden. Mr. Lonsdale
concluded that it had deserted its sickly mate; but after an absence of
twenty-four hours it returned, and apparently communicated the result of
its successful exploration, for both then started along the same track
and disappeared over the wall.

Even in the highest class of the Mollusca, namely the Cephalopoda or
cuttle-fishes, in which the sexes are separate, secondary sexual
characters of the kind which we are here considering, do not, as far as
I can discover, occur. This is a surprising circumstance, as these
animals possess highly-developed sense-organs and have considerable
mental powers, as will be admitted by every one who has watched their
artful endeavours to escape from an enemy.[411] Certain Cephalopoda,
however, are characterised by one extraordinary sexual character,
namely, that the male element collects within one of the arms or
tentacles, which is then cast off, and, clinging by its sucking-discs to
the female, lives for a time an independent life. So completely does the
cast-off arm resemble a separate animal, that it was described by Cuvier
as a parasitic worm under the name of Hectocotyle. But this marvellous
structure may be classed as a primary rather than as a secondary sexual

Although with the Mollusca sexual selection does not seem to have come
into play; yet many univalve and bivalve shells, such as volutes, cones,
scallops, &c., are beautifully coloured and shaped. The colours do not
appear in most cases to be of any use as a protection; they are probably
the direct result, as in the lowest classes, of the nature of the
tissues; the patterns and the sculpture of the shell depending on its
manner of growth. The amount of light seems to a certain extent to be
influential; for although, as repeatedly stated by Mr. Gwyn Jeffreys,
the shells of some species living at a profound depth are brightly
coloured, yet we generally see the lower surfaces and the parts covered
by the mantle less highly coloured than the upper and exposed
surfaces.[412] In some cases, as with shells living amongst corals or
brightly-tinted sea-weeds, the bright colours may serve as a protection.
But many of the nudibranch mollusca, or sea-slugs, are as beautifully
coloured as any shells, as may be seen in Messrs. Alder and Hancock’s
magnificent work; and from information kindly given me by Mr. Hancock,
it is extremely doubtful whether these colours usually serve as a
protection. With some species this may be the case, as with one which
lives on the green leaves of algæ, and is itself bright-green. But many
brightly-coloured, white or otherwise conspicuous species, do not seek
concealment; whilst again some equally conspicuous species, as well as
other dull-coloured kinds, live under stones and in dark recesses. So
that with these nudibranch molluscs, colour apparently does not stand in
any close relation to the nature of the places which they inhabit.

These naked sea-slugs are hermaphrodites, yet they pair together, as do
land-snails, many of which have extremely pretty shells. It is
conceivable that two hermaphrodites, attracted by each others’ greater
beauty, might unite and leave offspring which would inherit their
parents’ greater beauty. But with such lowly-organised creatures this is
extremely improbable. Nor is it at all obvious how the offspring from
the more beautiful pairs of hermaphrodites would have any advantage, so
as to increase in numbers, over the offspring of the less beautiful,
unless indeed vigour and beauty generally coincided. We have not here a
number of males becoming mature before the females, and the more
beautiful ones selected by the more vigorous females. If, indeed,
brilliant colours were beneficial to an hermaphrodite animal in relation
to its general habits of life, the more brightly-tinted individuals
would succeed best and would increase in number; but this would be a
case of natural and not of sexual selection.

_Sub-kingdom of the Vermes or Annulosa_: Class, _Annelida (or
Sea-worms)_.—In this class, although the sexes (when separate)
sometimes differ from each other in characters of such importance that
they have been placed under distinct genera or even families, yet the
differences do not seem of the kind which can be safely attributed to
sexual selection. These animals, like those in the preceding classes,
apparently stand too low in the scale, for the individuals of either sex
to exert any choice in selecting a partner, or for the individuals of
the same sex to struggle together in rivalry.

_Sub-kingdom of the Arthropoda_: Class, _Crustacea_.—In this great
class we first meet with undoubted secondary sexual characters, often
developed in a remarkable manner. Unfortunately the habits of
crustaceans are very imperfectly known, and we cannot explain the uses
of many structures peculiar to one sex. With the lower parasitic species
the males are of small size, and they alone are furnished with perfect
swimming-legs, antennæ and sense-organs; the females being destitute of
these organs, with their bodies often consisting of a mere distorted
mass. But these extraordinary differences between the two sexes are no
doubt related to their widely different habits of life, and consequently
do not concern us. In various crustaceans, belonging to distinct
families, the anterior antennæ are furnished with peculiar thread-like
bodies, which are believed to act as smelling-organs, and these are much
more numerous in the males than in the females. As the males, without
any unusual development of their olfactory organs, would almost
certainly be able sooner or later to find the females, the increased
number of the smelling-threads has probably been acquired through sexual
selection, by the better provided males having been the most successful
in finding partners and in leaving offspring. Fritz Müller has described
a remarkable dimorphic species of Tanais, in which the male is
represented by two distinct forms, never graduating into each other. In
the one form the male is furnished with more numerous smelling-threads,
and in the other form with more powerful and more elongated chelæ or
pincers which serve to hold the female. Fritz Müller suggests that these
differences between the two male forms of the same species must have
originated in certain individuals having varied in the number of the
smelling-threads, whilst other individuals varied in the shape and size
of their chelæ; so that of the former, those which were best able to
find the female, and of the latter, those which were best able to hold
her when found, have left the greater number of progeny to inherit their
respective advantages.[413]

[Illustration: Fig. 3. Labidocera Darwinii, (from Lubbock).

_a._ Part of right-hand anterior antenna of male, forming a prehensile

_b._ Posterior pair of thoracic legs of male.

_c._ Ditto of female.]

In some of the lower crustaceans, the right-hand anterior antenna of the
male differs greatly in structure from the left-hand one, the latter
resembling in its simple tapering joints the antennæ of the female. In
the male the modified antenna is either swollen in the middle or
angularly bent, or converted (fig. 3) into an elegant, and sometimes
wonderfully complex, prehensile organ.[414] It serves, as I hear from
Sir J. Lubbock, to hold the female, and for this same purpose one of the
two posterior legs (_b_) on the same side of the body is converted into
a forceps. In another family the inferior or posterior antennæ are
“curiously zigzagged” in the males alone.

[Illustration: Fig. 4. Anterior part of body of Callianassa (from
Milne-Edwards), showing the unequal and differently-constructed right
and left-hand chelæ of the male.

N.B.—The artist by mistake has reversed the drawing, and made the
left-hand chela the largest.]

[Illustration: Fig. 5. Second leg of male Orchestia Tucuratinga (from
Fritz Müller).]

[Illustration: Fig. 6. Ditto of female.]

In the higher crustaceans the anterior legs form a pair of chelæ or
pincers, and these are generally larger in the male than in the female.
In many species the chelæ on the opposite sides of the body are of
unequal size, the right-hand one being, as I am informed by Mr. C.
Spence Bate, generally, though not invariably, the largest. This
inequality is often much greater in the male than in the female. The two
chelæ also often differ in structure (figs. 4, 5, and 6), the smaller one
resembling those of the female. What advantage is gained by their
inequality in size on the opposite sides of the body, and by the
inequality being much greater in the male than in the female; and why,
when they are of equal size, both are often much larger in the male than
in the female, is not known. The chelæ are sometimes of such length and
size that they cannot possibly be used, as I hear from Mr. Spence Bate,
for carrying food to the mouth. In the males of certain freshwater
prawns (Palæmon) the right leg is actually longer than the whole
body.[415] It is probable that the great size of one leg with its chelæ
may aid the male in fighting with his rivals; but this use will not
account for their inequality in the female on the opposite sides
of the body. In Gelasimus, according to a statement quoted by
Milne-Edwards,[416] the male and female live in the same burrow, which
is worth notice, as shewing that they pair, and the male closes the
mouth of the burrow with one of its chelæ, which is enormously
developed; so that here it indirectly serves as a means of defence.
Their main use, however, probably is to seize and to secure the female,
and this in some instances, as with Gammarus, is known to be the case.
The sexes, however, of the common shore-crab (_Carcinus mænas_), as Mr.
Spence Bate informs me, unite directly after the female has moulted her
hard shell, and when she is so soft that she would be injured if seized
by the strong pincers of the male; but as she is caught and carried
about by the male previously to the act of moulting, she could then be
seized with impunity.

Fritz Müller states that certain species of Melita are distinguished
from all other amphipods by the females having “the coxal lamellæ of the
penultimate pair of feet produced into hook-like processes, of which the
males lay hold with the hands of the first pair.” The development of
these hook-like processes probably resulted from those females which
were the most securely held during the act of reproduction, having left
the largest number of offspring. Another Brazilian amphipod (_Orchestia
Darwinii_, fig. 7) is described by Fritz Müller, as presenting a case of
dimorphism, like that of Tanais; for there are two male forms, which
differ in the structure of their chelæ.[417] As chelæ of either shape
would certainly have sufficed to hold the female, for both are now used
for this purpose, the two male forms probably originated, by some having
varied in one manner and some in another; both forms having derived
certain special, but nearly equal advantages, from their differently
shaped organs.

It is not known that male crustaceans fight together for the possession
of the females, but this is probable; for with most animals when the
male is larger than the female, he seems to have acquired his greater
size by having conquered during many generations other males. Now Mr.
Spence Bate informs me that in most of the crustacean orders, especially
in the highest or the Brachyura, the male is larger than the female; the
parasitic genera, however, in which the sexes follow different habits of
life, and most of the Entomostraca must be excepted. The chelæ of many
crustaceans are weapons well adapted for fighting. Thus a Devil-crab
(_Portunus puber_) was seen by a son of Mr. Bate fighting with a
_Carcinus mænas_, and the latter was soon thrown on its back, and had
every limb torn from its body. When several males of a Brazilian
Gelasimus, a species furnished with immense pincers, were placed
together by Fritz Müller in a glass vessel, they mutilated and killed
each other. Mr. Bate put a large male _Carcinus mænas_ into a pan of
water, inhabited by a female paired with a smaller male; the latter was
soon dispossessed, but, as Mr. Bate adds, “if they fought, the victory
was a bloodless one, for I saw no wounds.” This same naturalist
separated a male sand-skipper (so common on our sea-shores), _Gammarus
marinus_, from its female, both of which were imprisoned in the same
vessel with many individuals of the same species. The female being thus
divorced joined her comrades. After an interval the male was again put
into the same vessel and he then, after swimming about for a time,
dashed into the crowd, and without any fighting at once took away his
wife. This fact shews that in the Amphipoda, an order low in the scale,
the males and females recognise each other, and are mutually attached.

[Illustration: Fig. 7. Orchestia Darwinii (from Fritz Müller), showing
the differently-constructed chelæ of the two male forms.]

The mental powers of the Crustacea are probably higher than might have
been expected. Any one who has tried to catch one of the shore-crabs, so
numerous on many tropical coasts, will have perceived how wary and alert
they are. There is a large crab (_Birgus latro_), found on coral
islands, which makes at the bottom of a deep burrow a thick bed of the
picked fibres of the cocoa-nut. It feeds on the fallen fruit of this
tree by tearing off the husk, fibre by fibre; and it always begins at
that end where the three eye-like depressions are situated. It then
breaks through one of these eyes by hammering with its heavy front
pincers, and turning round, extracts the albuminous core with its narrow
posterior pincers. But these actions are probably instinctive, so that
they would be performed as well by a young as by an old animal. The
following case, however, can hardly be so considered: a trustworthy
naturalist, Mr. Gardner,[418] whilst watching a shore-crab (Gelasimus)
making its burrow, threw some shells towards the hole. One rolled in,
and three other shells remained within a few inches of the mouth. In
about five minutes the crab brought out the shell which had fallen in,
and carried it away to the distance of a foot; it then saw the three
other shells lying near, and evidently thinking that they might likewise
roll in, carried them to the spot where it had laid the first. It would,
I think, be difficult to distinguish this act from one performed by man
by the aid of reason.

With respect to colour which so often differs in the two sexes of
animals belonging to the higher classes, Mr. Spence Bate does not know
of any well-marked instances with our British crustaceans. In some
cases, however, the male and female differ slightly in tint, but Mr.
Bate thinks not more than may be accounted for by their different habits
of life, such as by the male wandering more about and being thus more
exposed to the light. In a curious Bornean crab, which inhabits sponges,
Mr. Bate could always distinguish the sexes by the male not having the
epidermis so much rubbed off. Dr. Power tried to distinguish by colour
the sexes of the species which inhabit the Mauritius, but always failed,
except with one species of Squilla, probably the _S. stylifera_, the
male of which is described as being “of a beautiful blueish-green,” with
some of the appendages cherry-red, whilst the female is clouded with
brown and grey, “with the red about her much less vivid than in the
male.”[419] In this case, we may suspect the agency of sexual selection.
With Saphirina (an oceanic genus of Entomostraca, and therefore low in
the scale) the males are furnished with minute shields or cell-like
bodies, which exhibit beautiful changing colours; these being absent in
the females, and in the case of one species in both sexes.[420] It
would, however, be extremely rash to conclude that these curious organs
serve merely to attract the females. In the female of a Brazilian
species of Gelasimus, the whole body, as I am informed by Fritz Müller,
is of a nearly uniform greyish-brown. In the male the posterior part of
the cephalo-thorax is pure white, with the anterior part of a rich
green, shading into dark brown; and it is remarkable that these colours
are liable to change in the course of a few minutes—the white becoming
dirty grey or even black, the green “losing much of its brilliancy.” The
males apparently are much more numerous than the females. It deserves
especial notice that they do not acquire their bright colours until they
become mature. They differ also from the females in the larger size of
their chelæ. In some species of the genus, probably in all, the sexes
pair and inhabit the same burrow. They are also, as we have seen, highly
intelligent animals. From these various considerations it seems highly
probable that the male in this species has become gaily ornamented in
order to attract or excite the female.

It has just been stated that the male Gelasimus does not acquire his
conspicuous colours until mature and nearly ready to breed. This seems
the general rule in the whole class with the many remarkable differences
in structure between the two sexes. We shall hereafter find the same law
prevailing throughout the great sub-kingdom of the Vertebrata, and in
all cases it is eminently distinctive of characters which have been
acquired through sexual selection. Fritz Müller[421] gives some
striking instances of this law; thus the male sand-hopper (Orchestia)
does not acquire his large claspers, which are very differently
constructed from those of the female, until nearly full-grown; whilst
young his claspers resemble those of the female. Thus, again, the male
Brachyscelus possesses, like all other amphipods, a pair of posterior
antennæ; the female, and this is a most extraordinary circumstance, is
destitute of them, and so is the male as long as he remains immature.

Class, _Arachnida_ (Spiders).—The males are often darker, but sometimes
lighter than the females, as may be seen in Mr. Blackwall’s magnificent
work.[422] In some species the sexes differ conspicuously from each
other in colour; thus the female of _Sparassus smaragdulus_ is
dullish-green; whilst the adult male has the abdomen of a fine yellow,
with three longitudinal stripes of rich red. In some species of Thomisus
the two sexes closely resemble each other; in others they differ much;
thus in _T. citreus_ the legs and body of the female are pale-yellow or
green, whilst the front legs of the male are reddish-brown: in _T.
floricolens_, the legs of the female are pale-green, those of the male
being ringed in a conspicuous manner with various tints. Numerous
analogous cases could be given in the genera Epeira, Nephila,
Philodromus, Theridion, Linyphia, &c. It is often difficult to say which
of the two sexes departs most from the ordinary coloration of the genus
to which the species belong; but Mr. Blackwall thinks that, as a
general rule, it is the male. Both sexes whilst young, as I am informed
by the same author, usually resemble each other; and both often undergo
great changes in colour during their successive moults before arriving
at maturity. In other cases the male alone appears to change colour.
Thus the male of the above-mentioned brightly-coloured Sparassus at
first resembles the female and acquires his peculiar tints only when
nearly adult. Spiders are possessed of acute senses, and exhibit much
intelligence. The females often shew, as is well known, the strongest
affection for their eggs, which they carry about enveloped in a silken
web. On the whole it appears probable that well-marked differences in
colour between the sexes have generally resulted from sexual selection,
either on the male or female side. But doubts may be entertained on this
head from the extreme variability in colour of some species, for
instance of _Theridion lineatum_, the sexes of which differ when adult;
this great variability indicates that their colours have not been
subjected to any form of selection.

Mr. Blackwall does not remember to have seen the males of any species
fighting together for the possession of the female. Nor, judging from
analogy, is this probable; for the males are generally much smaller than
the females, sometimes to an extraordinary degree.[423] Had the males
been in the habit of fighting together, they would, it is probable, have
gradually acquired greater size and strength. Mr. Blackwall has
sometimes seen two or more males on the same web with a single female;
but their courtship is too tedious and prolonged an affair to be easily
observed. The male is extremely cautious in making his advances, as the
female carries her coyness to a dangerous pitch. De Geer saw a male that
“in the midst of his preparatory caresses was seized by the object of
his attentions, enveloped by her in a web and then devoured, a sight
which, as he adds, filled him with horror and indignation.”[424]

Westring has made the interesting discovery that the males of several
species of Theridion[425] have the power of making a stridulating sound
(like that made by many beetles and other insects, but feebler), whilst
the females are quite mute. The apparatus consists of a serrated ridge
at the base of the abdomen, against which the hard hinder part of the
thorax is rubbed; and of this structure not a trace could be detected in
the females. From the analogy of the Orthoptera and Homoptera, to be
described in the next chapter, we may feel almost sure that the
stridulation serves, as Westring remarks, either to call or to excite
the female; and this is the first case in the ascending scale of the
animal kingdom, known to me, of sounds emitted for this purpose.

Class, _Myriapoda_.—In neither of the two orders in this class,
including the millipedes and centipedes, can I find any well-marked
instances of sexual differences such as more particularly concern us. In
_Glomeris limbata_, however, and perhaps in some few other species, the
males differ slightly in colour from the females; but this Glomeris is a
highly variable species. In the males of the Diplopoda, the legs
belonging to one of the anterior segments of the body, or to the
posterior segment, are modified into prehensile hooks which serve to
secure the female. In some species of Iulus the tarsi of the male are
furnished with membranous suckers for the same purpose. It is a much
more unusual circumstance, as we shall see when we treat of Insects,
that it is the female in Lithobius which is furnished with prehensile
appendages at the extremity of the body for holding the male.[426]



  Diversified structures possessed by the males for seizing the
  females—Differences between the sexes, of which the meaning is
  not understood—Difference in size between the
  sexes—Thysanura—Diptera—Hemiptera—Homoptera, musical powers
  possessed by the males alone—Orthoptera, musical instruments
  of the males, much diversified in structure; pugnacity;
  colours—Neuroptera, sexual differences in colour—Hymenoptera,
  pugnacity and colours—Coleoptera, colours; furnished with
  great horns, apparently as an ornament; battles; stridulating
  organs generally common to both sexes.

In the immense class of insects the sexes sometimes differ in their
organs for locomotion, and often in their sense-organs, as in the
pectinated and beautifully plumose antennæ of the males of many species.
In one of the Ephemeræ, namely Chloëon, the male has great pillared
eyes, of which the female is entirely destitute.[427] The ocelli are
absent in the females of certain other insects, as in the Mutillidæ,
which are likewise destitute of wings. But we are chiefly concerned with
structures by which one male is enabled to conquer another, either in
battle or courtship, through his strength, pugnacity, ornaments, or
music. The innumerable contrivances, therefore, by which the male is
able to seize the female, may be briefly passed over. Besides the
complex structures at the apex of the abdomen, which ought perhaps to be
ranked as primary organs,[428] “it is astonishing,” as Mr. B. D.
Walsh[429] has remarked, “how many different organs are worked in by
nature, for the seemingly insignificant object of enabling the male to
grasp the female firmly.” The mandibles or jaws are sometimes used for
this purpose; thus the male _Corydalis cornutus_ (a neuropterous insect
in some degree allied to the Dragon-flies, &c.) has immense curved jaws,
many times longer than those of the female; and they are smooth instead
of being toothed, by which means he is enabled to seize her without
injury.[430] One of the stag-beetles of North America (_Lucanus
elaphus_) uses his jaws, which are much larger than those of the female,
for the same purpose, but probably likewise for fighting. In one of the
sand-wasps (_Ammophila_) the jaws in the two sexes are closely alike,
but are used for widely different purposes; the males, as Professor
Westwood observes, “are exceedingly ardent, seizing their partners round
the neck with their sickle-shaped jaws;”[431] whilst the females use
these organs for burrowing in sand-banks and making their nests.

[Illustration: Fig. 8. Crabro cribrarius. Upper figure, male: lower
figure, female.]

The tarsi of the front-legs are dilated in many male beetles, or are
furnished with broad cushions of hairs; and in many genera of
water-beetles they are armed with a round flat sucker, so that the male
may adhere to the slippery body of the female. It is a much more unusual
circumstance that the females of some water-beetles (Dytiscus) have
their elytra deeply grooved, and in _Acilius sulcatus_ thickly set with
hairs, as an aid to the male. The females of some other water-beetles
(Hydroporus) have their elytra punctured for the same object.[432] In
the male of _Crabro cribrarius_ (fig. 8.), it is the tibia which is
dilated into a broad horny plate, with minute membraneous dots, giving
to it a singular appearance like that of a riddle.[433] In the male of
Penthe (a genus of beetles) a few of the middle joints of the antennæ
are dilated and furnished on the inferior surface with cushions of
hair, exactly like those on the tarsi of the Carabidæ, “and obviously
for the same end.” In male dragon-flies, “the appendages at the tip of
the tail are modified in an almost infinite variety of curious patterns
to enable them to embrace the neck of the female.” Lastly in the males
of many insects, the legs are furnished with peculiar spines, knobs or
spurs; or the whole leg is bowed or thickened, but this is by no means
invariably a sexual character; or one pair, or all three pairs are
elongated, sometimes to an extravagant length.[434]

[Illustration: Fig. 9. Taphroderes distortus (much enlarged). Upper
figure, male; lower figure, female.]

In all the orders, the sexes of many species present differences, of
which the meaning is not understood. One curious case is that of a
beetle (fig. 9), the male of which has the left mandible much enlarged;
so that the mouth is greatly distorted. In another Carabidous beetle,
the Eurygnathus,[435] we have the unique case, as far as known to Mr.
Wollaston, of the head of the female being much broader and larger,
though in a variable degree, than that of the male. Any number of such
cases could be given. They abound in the Lepidoptera: one of the most
extraordinary is that certain male butterflies have their fore-legs more
or less atrophied, with the tibiæ and tarsi reduced to mere rudimentary
knobs. The wings, also, in the two sexes often differ in neuration,[436]
and sometimes considerably in outline, as in the _Aricoris epitus_,
which was shown to me in the British Museum by Mr. A. Butler. The males
of certain South American butterflies have tufts of hair on the margins
of the wings, and horny excrescences on the discs of the posterior
pair.[437] In several British butterflies, the males alone, as shewn by
Mr. Wonfor, are in parts clothed with peculiar scales.

The purpose of the luminosity in the female glow-worm is likewise not
understood; for it is very doubtful whether the primary use of the light
is to guide the male to the female. It is no serious objection to this
latter belief that the males emit a feeble light; for secondary sexual
characters proper to one sex are often developed in a slight degree in
the other sex. It is a more valid objection that the larvæ shine, and in
some species brilliantly: Fritz Müller informs me that the most luminous
insect which he ever beheld in Brazil, was the larva of some beetle.
Both sexes of certain luminous species of Elater emit light. Kirby and
Spence suspect that the phosphorescence serves to frighten and drive
away enemies.

_Difference in Size between the Sexes._—With insects of all kinds the
males are commonly smaller than the females;[438] and this difference
can often be detected even in the larval state. So considerable is the
difference between the male and female cocoons of the silk-moth
(_Bombyx mori_), that in France they are separated by a particular mode
of weighing.[439] In the lower classes of the animal kingdom, the
greater size of the females seems generally to depend on their
developing an enormous number of ova; and this may to a certain extent
hold good with insects. But Dr. Wallace has suggested a much more
probable explanation. He finds, after carefully attending to the
development of the caterpillars of _Bombyx cynthia_ and _yamamai_, and
especially of some dwarfed caterpillars reared from a second brood on
unnatural food, “that in proportion as the individual moth is finer, so
is the time required for its metamorphosis longer; and for this reason
the female, which is the larger and heavier insect, from having to carry
her numerous eggs, will be preceded by the male, which is smaller and
has less to mature.”[440] Now as most insects are short-lived, and as
they are exposed to many dangers, it would manifestly be advantageous to
the female to be impregnated as soon as possible. This end would be
gained by the males being first matured in large numbers ready for the
advent of the females; and this again would naturally follow, as Mr. A.
E. Wallace has remarked,[441] through natural selection; for the smaller
males would be first matured, and thus would procreate a large number of
offspring which would inherit the reduced size of their male parents,
whilst the larger males from being matured later would leave fewer

There are, however, exceptions to the rule of male insects being smaller
than the females; and some of these exceptions are intelligible. Size
and strength would be an advantage to the males, which fight for the
possession of the female; and in these cases the males, as with the
stag-beetle (Lucanus), are larger than the females. There are, however,
other beetles which are not known to fight together, of which the males
exceed the females in size; and the meaning of this fact is not known;
but in some of these cases, as with the huge Dynastes and Megasoma, we
can at least see that there would be no necessity for the males to be
smaller than the females, in order to be matured before them, for these
beetles are not short-lived, and there would be ample time for the
pairing of the sexes. So, again, male dragon-flies (Libellulidæ) are
sometimes sensibly larger, and never smaller, than the females;[442] and
they do not, as Mr. MacLachlan believes, generally pair with the
females, until a week or fortnight has elapsed, and until they have
assumed their proper masculine colours. But the most curious case,
shewing on what complex and easily-overlooked relations, so trifling a
character as a difference in size between the sexes may depend, is that
of the aculeate Hymenoptera; for Mr. F. Smith informs me that throughout
nearly the whole of this large group the males, in accordance with the
general rule, are smaller than the females and emerge about a week
before them; but amongst the Bees, the males of _Apis mellifica_,
_Anthidium manicatum_ and _Anthophora acervorum_, and amongst the
Fossores, the males of the _Methoca ichneumonides_, are larger than the
females. The explanation of this anomaly is that a marriage-flight is
absolutely necessary with these species, and the males require great
strength and size in order to carry the females through the air.
Increased size has here been acquired in opposition to the usual
relation between size and the period of development, for the males,
though larger, emerge before the smaller females.

We will now review the several Orders, selecting such facts as more
particularly concern us. The Lepidoptera (Butterflies and Moths) will be
retained for a separate chapter.

Order, _Thysanura_.—The members of this Order are lowly organised for
their class. They are wingless, dull-coloured, minute insects, with
ugly, almost misshapen heads and bodies. The sexes do not differ; but
they offer one interesting fact, by showing that the males pay sedulous
court to their females even low down in the animal scale. Sir J.
Lubbock[443] in describing the _Smynthurus luteus_, says: “it is very
amusing to see these little creatures coquetting together. The male,
which is much smaller than the female, runs round her, and they butt one
another, standing face to face, and moving backward and forward like two
playful lambs. Then the female pretends to run away and the male runs
after her with a queer appearance of anger, gets in front and stands
facing her again; then she turns coyly round, but he, quicker and more
active, scuttles round too, and seems to whip her with his antennæ; then
for a bit they stand face to face, play with their antennæ, and seem to
be all in all to one another.”

Order, _Diptera_ (Flies).—The sexes differ little in colour. The
greatest difference, known to Mr. F. Walker, is in the genus Bibio, in
which the males are blackish or quite black, and the females obscure
brownish-orange. The genus Elaphomyia, discovered by Mr. Wallace[444] in
New Guinea, is highly remarkable, as the males are furnished with horns,
of which the females are quite destitute. The horns spring from beneath
the eyes, and curiously resemble those of stags, being either branched
or palmated. They equal in length the whole of the body in one of the
species. They might be thought to serve for fighting, but as in one
species they are of a beautiful pink colour, edged with black, with a
pale central stripe, and as these insects have altogether a very elegant
appearance, it is perhaps more probable that the horns serve as
ornaments. That the males of some Diptera fight together is certain; for
Prof. Westwood[445] has several times seen this with some species of
Tipula or Harry-long-legs. Many observers believe that when gnats
(Culicidæ) dance in the air in a body, alternately rising and falling,
the males are courting the females. The mental faculties of the Diptera
are probably fairly well developed, for their nervous system is more
highly developed than in most other Orders of insects.[446]

Order, _Hemiptera_ (Field-Bugs).—Mr. J. W. Douglas, who has
particularly attended to the British species, has kindly given me an
account of their sexual differences. The males of some species are
furnished with wings, whilst the females are wingless; the sexes differ
in the form of the body and elytra; in the second joints of their
antennæ and in their tarsi; but as the signification of these
differences is quite unknown, they may be here passed over. The females
are generally larger and more robust than the males. With British, and,
as far as Mr. Douglas knows, with exotic species, the sexes do not
commonly differ much in colour; but in about six British species the
male is considerably darker than the female, and in about four other
species the female is darker than the male. Both sexes of some species
are beautifully marked with vermilion and black. It is doubtful whether
these colours serve as a protection. If in any species the males had
differed from the females in an analogous manner, we might have been
justified in attributing such conspicuous colours to sexual selection
with transference to both sexes.

Some species of Reduvidæ make a stridulating noise; and, in the case of
_Pirates stridulus_, this is said[447] to be effected by the movement of
the neck within the pro-thoracic cavity. According to Westring,
_Reduvius personatus_ also stridulates. But I have not been able to
learn any particulars about these insects; nor have I any reason to
suppose that they differ sexually in this respect.

Order, _Homoptera._—Every one who has wandered in a tropical forest
must have been astonished at the din made by the male Cicadæ. The
females are mute; as the Grecian poet Xenarchus says, “Happy the Cicadas
live, since they all have voiceless wives.” The noise thus made could be
plainly heard on board the “Beagle,” when anchored at a quarter of a
mile from the shore of Brazil; and Captain Hancock says it can be heard
at the distance of a mile. The Greeks formerly kept, and the Chinese now
keep, these insects in cages for the sake of their song, so that it
must be pleasing to the ears of some men.[448] The Cicadidæ usually sing
during the day; whilst the Fulgoridæ appear to be night-songsters. The
sound, according to Landois,[449] who has recently studied the subject,
is produced by the vibration of the lips of the spiracles, which are set
into motion by a current of air emitted from the tracheæ. It is
increased by a wonderfully complex resounding apparatus, consisting of
two cavities covered by scales. Hence the sound may truly be called a
voice. In the female the musical apparatus is present, but very much
less developed than in the male, and is never used for producing sound.

With respect to the object of the music, Dr. Hartman in speaking of the
_Cicada septemdecim_ of the United States, says,[450] “the drums are now
(June 6th and 7th, 1851) heard in all directions. This I believe to be
the marital summons from the males. Standing in thick chestnut sprouts
about as high as my head, where hundreds were around me, I observed the
females coming around the drumming males.” He adds, “this season (Aug.
1868) a dwarf pear-tree in my garden produced about fifty larvæ of _Cic.
pruinosa_; and I several times noticed the females to alight near a male
while he was uttering his clanging notes.” Fritz Müller writes to me
from S. Brazil that he has often listened to a musical contest between
two or three males of a Cicada, having a particularly loud voice, and
seated at a considerable distance from each other. As soon as the first
had finished his song, a second immediately began; and after he had
concluded, another began, and so on. As there is so much rivalry between
the males, it is probable that the females not only discover them by the
sounds emitted, but that, like female birds, they are excited or allured
by the male with the most attractive voice.

I have not found any well-marked cases of ornamental differences between
the sexes of the Homoptera. Mr. Douglas informs me that there are three
British species, in which the male is black or marked with black bands,
whilst the females are pale-coloured or obscure.

Order, _Orthoptera_.—The males in the three saltatorial families
belonging to this Order are remarkable for their musical powers, namely
the Achetidæ or crickets, the Locustidæ for which there is no exact
equivalent name in English, and the Acridiidæ or grasshoppers. The
stridulation produced by some of the Locustidæ is so loud that it can be
heard during the night at the distance of a mile;[451] and that made by
certain species is not unmusical even to the human ear, so that the
Indians on the Amazons keep them in wicker cages. All observers agree
that the sounds serve either to call or excite the mute females. But it
has been noticed[452] that the male migratory locust of Russia (one of
the Acridiidæ) whilst coupled with the female, stridulates from anger or
jealousy when approached by another male. The house-cricket when
surprised at night uses its voice to warn its fellows.[453] In North
America the Katy-did (_Platyphyllum concavum_, one of the Locustidæ) is
described[454] as mounting on the upper branches of a tree, and in the
evening beginning “his noisy babble, while rival notes issue from the
neighbouring trees, and the groves resound with the call of
_Katy-did-she-did_, the live-long night.” Mr. Bates, in speaking of the
European field-cricket (one of the Achetidæ), says, “the male has been
observed to place itself in the evening at the entrance of its burrow,
and stridulate until a female approaches, when the louder notes are
succeeded by a more subdued tone, whilst the successful musician
caresses with his antennæ the mate he has won.”[455] Dr. Scudder was
able to excite one of these insects to answer him, by rubbing on a file
with a quill.[456] In both sexes a remarkable auditory apparatus has
been discovered by Von Siebold, situated in the front legs.[457]

[Illustration: Fig. 10. Gryllus campestris (from Landois).

Right-hand figure, under side of part of the wing-nervure, much
magnified, showing the teeth, _st_.

Left-hand figure, upper surface of wing-cover, with the projecting,
smooth nervure, _r._, across which the teeth (_st_) are scraped.]

In the three Families the sounds are differently produced. In the males
Of the Achetidæ both wing-covers have the same structure; and this in
the field-cricket (_Gryllus campestris_, fig. 10) consists, as
described by Landois,[458] of from 131 to 138 sharp, transverse ridges
or teeth (_st_) on the under side of one of the nervures of the
wing-cover. This toothed nervure is rapidly scraped across a projecting,
smooth, hard nervure (_r_) on the upper surface of the opposite wing.
First one wing is rubbed over the other, and then the movement is
reversed. Both wings are raised a little at the same time, so as to
increase the resonance. In some species the wing-covers of the males are
furnished at the base with a talc-like plate.[459] I have here given a
drawing (fig. 11) of the teeth on the under side of the nervure of
another species of Gryllus, viz. _G. domesticus_.

[Illustration: Fig. 11. Teeth of Nervure of Gryllus domesticus (from

In the Locustidæ the opposite wing-covers differ in structure (fig. 12),
and cannot, as in the last family, be indifferently used in a reversed
manner. The left wing, which acts as the bow of the fiddle, lies over
the right wing which serves as the fiddle itself. One of the nervures
(_a_) on the under surface of the former is finely serrated, and is
scraped across the prominent nervures on the upper surface of the
opposite or right wing. In our British _Phasgonura viridissima_ it
appeared to me that the serrated nervure is rubbed against the rounded
hind corner of the opposite wing, the edge of which is thickened,
coloured brown, and very sharp. In the right wing, but not in the left,
there is a little plate, as transparent as talc, surrounded by nervures,
and called the speculum. In _Ephippiger vitium_, a member of this same
family, we have a curious subordinate modification; for the wing-covers
are greatly reduced in size, but “the posterior part of the pro-thorax
is elevated into a kind of dome over the wing-covers, and which has
probably the effect of increasing the sound.”[460]

[Illustration: Fig. 12. Chlorocœlus Tanana (from Bates). _a_, _b_.
Lobes of opposite wing-covers.]

We thus see that the musical apparatus is more differentiated or
specialised in the Locustidæ, which includes I believe the most powerful
performers in the Order, than in the Achetidæ, in which both wing-covers
have the same structure and the same function.[461] Landois, however,
detected in one of the Locustidæ, namely in Decticus, a short and narrow
row of small teeth, mere rudiments, on the inferior surface of the
right wing-cover, which underlies the other and is never used as the
bow. I observed the same rudimentary structure on the under side of the
right wing-cover in _Phasgonura viridissima_. Hence we may with
confidence infer that the Locustidæ are descended from a form, in which,
as in the existing Achetidæ, both wing-covers had serrated nervures on
the under surface, and could be indifferently used as the bow; but that
in the Locustidæ the two wing-covers gradually became differentiated and
perfected, on the principle of the division of labour, the one to act
exclusively as the bow and the other as the fiddle. By what steps the
more simple apparatus in the Achetidæ originated, we do not know, but it
is probable that the basal portions of the wing-covers overlapped each
other formerly as at present, and that the friction of the nervures
produced a grating sound, as I find is now the case with the wing-covers
of the females.[462] A grating sound thus occasionally and accidentally
made by the males, if it served them ever so little as a love-call to
the females, might readily have been intensified through sexual
selection by fitting variations in the roughness of the nervures having
been continually preserved.

[Illustration: Fig. 13, Hind-leg of Stenobothrus pratorum: _r_, the
stridulating ridge; lower figure, the teeth, forming the ridge, much
magnified (from Landois).]

In the last and third Family, namely the Acridiidæ or grasshoppers, the
stridulation is produced in a very different manner, and is not so
shrill, according to Dr. Scudder, as in the preceding Families. The
inner surface of the femur (fig. 13, _r_) is furnished with a
longitudinal row of minute, elegant, lancet-shaped, elastic teeth, from
85 to 93 in number;[463] and these are scraped across the sharp,
projecting nervures on the wing-covers, which, are thus made to vibrate
and resound. Harris[464] says that when one of the males begins to play,
he first “bends the shank of the hind-leg beneath, the thigh, where it
is lodged in a furrow designed to receive it, and then draws the leg
briskly up and down. He does not play both fiddles together, but
alternately first upon one and then on the other.” In many species, the
base of the abdomen is hollowed out into a great cavity which is
believed to act as a resounding board. In Pneumora (fig. 14), a S.
African genus belonging to this same family, we meet with a new and
remarkable modification: in the males a small notched ridge projects
obliquely from each side of the abdomen, against which the hind femora
are rubbed.[465] As the male is furnished with wings, the female being
wingless, it is remarkable that the thighs are not rubbed in the usual
manner against the wing-covers; but this may perhaps be accounted for by
the unusually small size of the hind-legs. I have not been able to
examine the inner surface of the thighs, which, judging from analogy,
would be finely serrated. The species of Pneumora have been more
profoundly modified for the sake of stridulation than any other
orthopterous insect; for in the male the whole body has been converted
into a musical instrument, being distended with air, like a great
pellucid bladder, so as to increase the resonance. Mr. Trimen informs me
that at the Cape of Good Hope these insects make a wonderful noise
during the night There is one exception to the rule that the females in
these three Families are destitute of an efficient musical apparatus;
for both sexes of Ephippiger (Locustidæ) are said[466] to be thus
provided. This case may be compared with that of the reindeer, in which
species alone both sexes possess horns. Although the female orthoptera
are thus almost invariably mute, yet Landois[467] found rudiments of the
stridulating organs on the femora of the female Acridiidæ, and similar
rudiments on the under surface of the wing-covers of the female
Achetidæ; but he failed to find any rudiments in the females of
Decticus, one of the Locustidæ. In the Homoptera the mute females of
Cicada, have the proper musical apparatus in an undeveloped state; and
we shall hereafter meet in other divisions of the animal kingdom with
innumerable instances of structures proper to the male being present in
a rudimentary condition in the female. Such cases appear at first sight
to indicate that both sexes were primordially constructed in the same
manner, but that certain organs were subsequently lost by the females.
It is, however, a more probable view, as previously explained, that the
organs in question were acquired by the males and partially transferred
to the females.

[Illustration: Fig. 14. Pneumora (from specimens in the British Museum).
Upper figure, male; lower figure, female.]

Landois has observed another interesting fact, namely that in the
females of the Acridiidæ, the stridulating teeth on the femora remain
throughout life in the same condition in which they first appear in both
sexes during the larval state. In the males, on the other hand, they
become fully developed and acquire their perfect structure at the last
moult, when the insect is mature and ready to breed.

From the facts now given, we see that the means by which the males
produce their sounds are extremely diversified in the Orthoptera, and
are altogether different from those employed by the Homoptera. But
throughout the animal kingdom we incessantly find the same object
gained by the most diversified means; this being due to the whole
organisation undergoing in the course of ages multifarious changes; and
as part after part varies, different variations are taken advantage of
for the same general purpose. The diversification of the means for
producing sound in the three families of the Orthoptera and in the
Homoptera, impresses the mind with the high importance of these
structures to the males, for the sake of calling or alluring the
females. We need feel no surprise at the amount of modification which
the Orthoptera have undergone in this respect, as we now know, from Dr.
Scudder’s remarkable discovery,[468] that there has been more than ample
time. This naturalist has lately found a fossil insect in the Devonian
formation of New Brunswick, which is furnished with “the well-known
tympanum or stridulating apparatus of the male Locustidæ.” This insect,
though in most respects related to the Neuroptera, appears to connect,
as is so often the case with very ancient forms, the two Orders of the
Neuroptera and Orthoptera which are now generally ranked as quite

I have but little more to say on the Orthoptera. Some of the species are
very pugnacious: when two male field-crickets (_Gryllus campestris_) are
confined together, they fight till one kills the other; and the species
of Mantis are described as manœuvring with their sword-like
front-limbs, like hussars with their sabres. The Chinese keep these
insects in little bamboo cages and match them like game-cocks.[469] With
respect to colour, some exotic locusts are beautifully ornamented; the
posterior wings being marked with red, blue, and black; but as
throughout the Order the two sexes rarely differ much in colour, it is
doubtful whether they owe these bright tints to sexual selection.
Conspicuous colours may be of use to these insects as a protection, on
the principle to be explained in the next chapter, by giving notice to
their enemies that they are unpalatable. Thus it has been observed[470]
that an Indian brightly-coloured locust was invariably rejected when
offered to birds and lizards. Some cases, however, of sexual differences
in colour in this Order are known. The male of an American cricket[471]
is described as being as white as ivory, whilst the female varies from
almost white to greenish-yellow or dusky. Mr. Walsh informs me that the
adult male of _Spectrum femoratum_ (one of the Phasmidæ) “is of a
shining brownish-yellow colour; the adult female being of a dull,
opaque, cinereous-brown; the young of both sexes being green.” Lastly, I
may mention that the male of one curious kind of cricket[472] is
furnished with “a long membranous appendage, which falls over the face
like a veil;” but whether this serves as an ornament is not known.

Order, _Neuroptera_.—Little need here be said, except in regard to
colour. In the Ephemeridæ the sexes often differ slightly in their
obscure tints;[473] but it is not probable that the males are thus
rendered attractive to the females. The Libellulidæ or dragon-flies are
ornamented with splendid green, blue, yellow, and vermilion metallic
tints; and the sexes often differ. Thus, the males of some of the
Agrionidæ, as Prof. Westwood remarks[474] “are of a rich blue with black
wings, whilst the females are fine green with colourless wings.” But in
_Agrion Ramburii_ these colours are exactly reversed in the two
sexes.[475] In the extensive N. American genus of Hetærina, the males
alone have a beautiful carmine spot at the base of each wing. In _Anax
junius_ the basal part of the abdomen in the male is a vivid
ultra-marine blue, and in the female grass-green. In the allied genus
Gomphus, on the other hand, and in some other genera, the sexes differ
but little in colour. Throughout the animal kingdom, similar cases of
the sexes of closely-allied forms either differing greatly, or very
little, or not at all, are of frequent occurrence. Although with many
Libellulidæ there is so wide a difference in colour between the sexes,
it is often difficult to say which is the most brilliant; and the
ordinary coloration of the two sexes is exactly reversed, as we have
just seen, in one species of Agrion. It is not probable that their
colours in any case have been gained as a protection. As Mr. MacLachlan,
who has closely attended to this family, writes to me, dragon-flies—the
tyrants of the insect-world—are the least liable of any insect to be
attacked by birds or other enemies. He believes that their bright
colours serve as a sexual attraction. It deserves notice, as bearing on
this subject, that certain dragon-flies appear to be attracted by
particular colours: Mr. Patterson observed[476] that the species of
Agrionidæ, of which the males are blue, settled in numbers on the blue
float of a fishing line; whilst two other species were attracted by
shining white colours.

It is an interesting fact, first observed by Schelver, that the males,
in several genera belonging to two sub-families, when they first emerge
from the pupal state are coloured exactly like the females; but that
their bodies in a short time assume a conspicuous milky-blue tint, owing
to the exudation of a kind of oil, soluble in ether and alcohol. Mr.
MacLachlan believes that in the male of _Libellula depressa_ this change
of colour does not occur until nearly a fortnight after the
metamorphosis, when the sexes are ready to pair.

Certain species of Neurothemis present, according to Brauer[477] a
curious case of dimorphism, some of the females having their wings
netted in the usual manner; whilst other females have them “very richly
netted as in the males of the same species.” Brauer “explains the
phenomenon on Darwinian principles by the supposition that the close
netting of the veins is a secondary sexual character in the males.” This
latter character is generally developed in the males alone, but being,
like every other masculine character, latent in the female, is
occasionally developed in them. We have here an illustration of the
manner in which the two sexes of many animals have probably come to
resemble each other, namely by variations first appearing in the males,
being preserved in them, and then transmitted to and developed in the
females; but in this particular genus a complete transference is
occasionally and abruptly effected. Mr. MacLachlan informs me of another
case of dimorphism occurring in several species of Agrion in which a
certain number of individuals are found of an orange colour, and these
are invariably females. This is probably a case of reversion, for in
the true Libellulæ, when the sexes differ in colour, the females are
always orange or yellow, so that supposing Agrion to be descended from
some primordial form having the characteristic sexual colours of the
typical Libellulæ, it would not be surprising that a tendency to vary in
this manner should occur in the females alone.

Although many dragon-flies are such large, powerful, and fierce insects,
the males have not been observed by Mr. MacLachlan to fight together,
except, as he believes, in the case of some of the smaller species of
Agrion. In another very distinct group in this Order, namely in the
Termites or white ants, both sexes at the time of swarming may be seen
running about, “the male after the female, sometimes two chasing one
female, and contending with great eagerness who shall win the

Order, _Hymenoptera_.—That inimitable observer, M. Fabre,[479] in
describing the habits of Cerceris, a wasp-like insect, remarks that
“fights frequently ensue between the males for the possession of some
particular female, who sits an apparently unconcerned beholder of the
struggle for supremacy, and when the victory is decided, quietly flies
away in company with the conqueror.” Westwood[480] says that the males
of one of the saw-flies (Tenthredinæ) “have been found fighting
together, with their mandibles locked.” As M. Fabre speaks of the males
of Cerceris striving to obtain a particular female, it may be well to
bear in mind that insects belonging to this Order have the power of
recognising each other after long intervals of time, and are deeply
attached. For instance, Pierre Huber, whose accuracy no one doubts,
separated some ants, and when after an interval of four months they met
others which had formerly belonged to the same community, they mutually
recognised and caressed each other with their antennæ. Had they been
strangers they would have fought together. Again, when two communities
engage in a battle, the ants on the same side in the general confusion
sometimes attack each other, but they soon perceive their mistake, and
the one ant soothes the other.[481]

In this Order slight differences in colour, according to sex, are
common, but conspicuous differences are rare except in the family of
Bees; yet both sexes of certain groups are so brilliantly coloured—for
instance in Chrysis, in which vermilion and metallic greens
prevail—that we are tempted to attribute the result to sexual
selection. In the Ichneumonidæ, according to Mr. Walsh,[482] the males
are almost universally lighter coloured than the females. On the other
hand, in the Tenthredinidæ the males are generally darker than the
females. In the Siricidæ the sexes frequently differ; thus the male of
_Sirex juvencus_ is banded with orange, whilst the female is dark
purple; but it is difficult to say which sex is the most ornamented. In
_Tremex columbæ_ the female is much brighter coloured than the male.
With ants, as I am informed by Mr. F. Smith, the males of several
species are black, the females being testaceous. In the family of Bees,
especially in the solitary species, as I hear from the same
distinguished entomologist, the sexes often differ in colour. The males
are generally the brightest, and in Bombus as well as in Apathus, much
more variable in colour than the females. In _Anthophora retusa_ the
male is of a rich fulvous-brown, whilst the female is quite black: so
are the females of several species of Xylocopa, the males being bright
yellow. In an Australian bee (_Lestis bombylans_), the female is of an
extremely brilliant steel-blue, sometimes tinted with vivid green; the
male being of a bright brassy colour clothed with rich fulvous
pubescence. As in this group the females are provided with excellent
defensive weapons in their stings, it is not probable that they have
come to differ in colour from the males for the sake of protection.

_Mutilla Europæa_ emits a stridulating noise; and according to
Goureau[483] both sexes have this power. He attributes the sound to the
friction of the third and preceding abdominal segments; and I find that
these surfaces are marked with very fine concentric ridges, but so is
the projecting thoracic collar, on which the head articulates; and this
collar, when scratched with the point of a needle, emits the proper
sound. It is rather surprising that both sexes should have the power of
stridulating, as the male is winged and the female wingless. It is
notorious that Bees express certain emotions, as of anger, by the tone
of their humming, as do some dipterous insects; but I have not referred
to these sounds, as they are not known to be in any way connected with
the act of courtship.

Order, _Coleoptera_ (Beetles).—Many beetles are coloured so as to
resemble the surfaces which they habitually frequent. Other species are
ornamented with gorgeous metallic tints,—for instance, many Carabidæ,
which live on the ground and have the power of defending themselves by
an intensely acrid secretion,—the splendid diamond-beetles which are
protected by an extremely hard covering,—many species of Chrysomela,
such as _C. cerealis_, a large species beautifully striped with various
colours, and in Britain confined to the bare summit of Snowdon,—and a
host of other species. These splendid colours, which are often arranged
in stripes, spots, crosses and other elegant patterns, can hardly be
beneficial, as a protection, except in the case of some flower-feeding
species; and we cannot believe that they are purposeless. Hence the
suspicion arises, that they serve as a sexual attraction; but we have no
evidence on this head, for the sexes rarely differ in colour. Blind
beetles, which cannot of course behold each other’s beauty, never
exhibit, as I hear from Mr. Waterhouse, jun., bright colours, though
they often have polished coats: but the explanation of their obscurity
may be that blind insects inhabit caves and other obscure stations.

Some Longicorns, however, especially certain Prionidæ, offer an
exception to the common rule that the sexes of beetles do not differ in
colour. Most of these insects are large and splendidly coloured. The
males in the genus Pyrodes,[484] as I saw in Mr. Bates’ collection, are
generally redder but rather duller than the females, the latter being
coloured of a more or less splendid golden green. On the other hand, in
one species the male is golden-green, the female being richly tinted
with red and purple. In the genus Esmeralda the sexes differ so greatly
in colour that they have been ranked as distinct species: in one species
both are of a beautiful shining green, but the male has a red thorax. On
the whole, as far as I could judge, the females of those Prionidæ, in
which the sexes differ, are coloured more richly than the males; and
this does not accord with the common rule in regard to colour when
acquired through sexual selection.

[Illustration: Fig. 15. Chalcosoma atlas. Upper figure, male (reduced);
lower figure, female (nat. size).]

[Illustration: Fig. 16. Copris isidis. (Left-hand figures, males.)]

[Illustration: Fig. 17. Phanæus faunus.]

[Illustration: Fig. 18. Dipelicus cantori.]

[Illustration: Fig. 19. Onthophagus rangifer, enlarged.]

A most remarkable distinction between the sexes of many beetles is
presented by the great horns which rise from the head, thorax, or
clypeus of the males; and in some few cases from the under surface of
the body. These horns, in the great family of the Lamellicorns, resemble
those of various quadrupeds, such as stags, rhinoceroses, &c., and are
wonderful both from their size and diversified shapes. Instead of
describing them, I have given figures of the males and females of some
of the more remarkable forms. (Figs. 15 to 19.) The females generally
exhibit rudiments of the horns in the form of small knobs or ridges; but
some are destitute of even a rudiment. On the other hand, the horns are
nearly as well developed in the female as in the male of _Phanæus
lancifer_; and only a little less well developed in the females of some
other species of the same genus and of Copris. In the several
subdivisions of the family, the differences in structure of the horns do
not run parallel, as I am informed by Mr. Bates, with their more
important and characteristic differences; thus within the same natural
section of the genus Onthophagus, there are species which have either a
single cephalic horn, or two distinct horns.

In almost all cases, the horns are remarkable from their excessive
variability; so that a graduated series can be formed, from the most
highly developed males to others so degenerate that they can barely be
distinguished from the females. Mr. Walsh[485] found that in _Phanæus
carnifex_ the horns were thrice as long in some males as in others. Mr.
Bates, after examining above a hundred males of _Onthophagus rangifer_
(fig. 19), thought that he had at last discovered a species in which
the horns did not vary; but further research proved the contrary.

The extraordinary size of the horns, and their widely different
structure in closely-allied forms, indicate that they have been formed
for some important purpose; but their excessive variability in the males
of the same species leads to the inference that this purpose cannot be
of a definite nature. The horns do not show marks of friction, as if
used for any ordinary work. Some authors suppose[486] that as the males
wander much more than the females, they require horns as a defence
against their enemies; but in many cases the horns do not seem well
adapted for defence, as they are not sharp. The most obvious conjecture
is that they are used by the males for fighting together; but they have
never been observed to fight; nor could Mr. Bates, after a careful
examination of numerous species, find any sufficient evidence in their
mutilated or broken condition of their having been thus used. If the
males had been habitual fighters, their size would probably have been
increased through sexual selection, so as to have exceeded that of the
female; but Mr. Bates, after comparing the two sexes in above a hundred
species of the Copridæ, does not find in well-developed individuals any
marked difference in this respect. There is, moreover, one beetle,
belonging to the same great division of the Lamellicorns, namely
Lethrus, the males of which are known to fight, but they are not
provided with horns, though their mandibles are much larger than those
of the female.

The conclusion, which best agrees with the fact of the horns having been
so immensely yet not fixedly developed,—as shewn by their extreme
variability in the same species and by their extreme diversity in
closely-allied species—is that they have been acquired as ornaments.
This view will at first appear extremely improbable; but we shall
hereafter find with many animals, standing much higher in the scale,
namely fishes, amphibians, reptiles and birds, that various kinds of
crests, knobs, horns and combs have been developed apparently for this
sole purpose.

[Illustration: Fig. 20. Onitis furcifer, male, viewed from beneath.]

[Illustration: Fig. 21. Left-hand figure, male of Onitis furcifer,
viewed laterally. Right-hand figure, female. _a._ Rudiment of cephalic
horn. _b._ Trace of thoracic horn or crest.]

The males of _Onitis furcifer_ (fig. 20) are furnished with singular
projections on their anterior femora, and with a great fork or pair of
horns on the lower surface of the thorax. This situation seems extremely
ill adapted for the display of these projections, and they may be of
some real service; but no use can at present be assigned to them. It is
a highly remarkable fact, that although the males do not exhibit even a
trace of horns on the upper surface of the body, yet in the females a
rudiment of a single horn on the head (fig. 21, _a_), and of a crest
(_b_) on the thorax, are plainly visible. That the slight thoracic crest
in the female is a rudiment of a projection proper to the male, though
entirely absent in the male of this particular species, is clear: for
the female of _Bubas bison_ (a form which comes next to _Onitis_) has a
similar slight crest on the thorax, and the male has in the same
situation a great projection. So again there can be no doubt that the
little point (_a_) on the head of the female _Onitis furcifer_, as well
of the females of two or three allied species, is a rudimentary
representative of the cephalic horn, which is common to the males of so
many lamellicorn beetles, as in Phanæus, fig. 17. The males indeed of
some unnamed beetles in the British Museum, which are believed actually
to belong to the genus Onitis, are furnished with a similar horn. The
remarkable nature of this case will be best perceived by an
illustration: the Ruminant quadrupeds run parallel with the lamellicorn
beetles, in some females possessing horns as large as those of the male,
in others having them much smaller, or existing as mere rudiments
(though this is as rare with ruminants as it is common with
Lamellicorns), or in having none at all. Now if a new species of deer or
sheep were discovered with the female bearing distinct rudiments of
horns, whilst the head of the male was absolutely smooth, we should have
a case like that of _Onitis furcifer_.

In this case the old belief of rudiments having been created to complete
the scheme of nature is so far from holding good, that all ordinary
rules are completely broken through. The view which seems the most
probable is that some early progenitor of Onitis acquired, like other
Lamellicorns, horns on the head and thorax, and then transferred them,
in a rudimentary condition, as with so many existing species, to the
female, by whom they have ever since been retained. The subsequent loss
of the horns by the male may have resulted through the principle of
compensation from the development of the projections on the lower
surface, whilst the female has not been thus affected, as she is not
furnished with these projections, and consequently has retained the
rudiments of the horns on the upper surface. Although this view is
supported by the case of Bledius immediately to be given, yet the
projections on the lower surface differ greatly in structure and
development in the males of the several species of Onitis, and are even
rudimentary in some; nevertheless the upper surface in all these species
is quite destitute of horns. As secondary sexual characters are so
eminently variable, it is possible that the projections on the lower
surface may have been first acquired by some progenitor of Onitis and
produced their effect through compensation, and then have been in
certain cases almost completely lost.

[Illustration: Fig. 22. Bledius taurus, magnified. Left-hand figure,
male; right-hand figure, female.]

All the cases hitherto given refer to the Lamellicorns, but the males of
some few other beetles, belonging to two widely distinct groups, namely,
the Curculionidæ and Staphylinidæ, are furnished with horns,—in the
former on the lower surface of the body,[487] in the latter on the upper
surface of the head and thorax. In the Staphylinidæ the horns of the
males in the same species are extraordinarily variable, just as we have
seen with the Lamellicorns. In Siagonium we have a case of dimorphism,
for the males can be divided into two sets, differing greatly in the
size of their bodies, and in the development of their horns, without any
intermediate gradations. In a species of Bledius (fig. 22), also
belonging to the Staphylinidæ, male specimens can be found in the same
locality, as Professor Westwood states, “in which the central horn of
the thorax is very large, but the horns of the head quite rudimental;
and others, in which the thoracic horn is much shorter, whilst the
protuberances on the head are long.”[488] Here, then, we apparently have
an instance of compensation of growth, which throws light on the curious
case just given of the loss of the upper horns by the males of _Onitis

_Law of Battle._—Some male beetles, which seem ill fitted for fighting,
nevertheless engage in conflicts for the possession of the females. Mr.
Wallace[489] saw two males of _Leptorhynchus angustatus_, a linear
beetle with a much elongated rostrum, “fighting for a female, who stood
close by busy at her boring. They pushed at each other with their
rostra, and clawed and thumped, apparently in the greatest rage.” The
smaller male, however, “soon ran away, acknowledging himself
vanquished.” In some few cases the males are well adapted for fighting,
by possessing great toothed mandibles, much larger than those of the
females. This is the case with the common stag-beetle (_Lucanus
cervus_), the males of which emerge from the pupal state about a week
before the other sex, so that several may often be seen pursuing the
same female. At this period they engage in fierce conflicts. When Mr. A.
H. Davis[490] enclosed two males with one female in a box, the larger
male severely pinched the smaller one, until he resigned his
pretensions. A friend informs me that when a boy he often put the males
together to see them fight, and he noticed that they were much bolder
and fiercer than the females, as is well known to be the case with the
higher animals. The males would seize hold of his finger, if held in
front, but not so the females. With many of the Lucanidæ, as well as
with the above-mentioned Leptorhynchus, the males are larger and more
powerful insects than the females. The two sexes of _Lethrus cephalotes_
(one of the Lamellicorns) inhabit the same burrow; and the male has
larger mandibles than the female. If, during the breeding-season, a
strange male attempts to enter the burrow, he is attacked; the female
does not remain passive, but closes the mouth of the burrow, and
encourages her mate by continually pushing him on from behind. The
action does not cease until the aggressor is killed or runs away.[491]
The two sexes of another lamellicorn beetle, the _Ateuchus cicatricosus_
live in pairs, and seem much attached to each other; the male excites
the female to roll the balls of dung in which the ova are deposited; and
if she is removed, he becomes much agitated. If the male is removed, the
female ceases all work, and as M. Brulerie[492] believes, would remain
on the spot until she died.

The great mandibles of the male Lucanidæ are extremely variable both in
size and structure, and in this respect resemble the horns on the head
and thorax of many male Lamellicorns and Staphylinidæ. A perfect series
can be formed from the best-provided to the worst-provided or degenerate
males. Although the mandibles of the common stag-beetle, and probably of
many other species, are used as efficient weapons for fighting, it is
doubtful whether their great size can thus be accounted for. We have
seen that with the _Lucanus elaphus_ of N. America they are used for
seizing the female. As they are so conspicuous and so elegantly
branched, the suspicion has sometimes crossed my mind that they may be
serviceable to the males as an ornament, in the same manner as the horns
on the head and thorax of the various above described species. The male
_Chiasognathus grantii_ of S. Chile—a splendid beetle belonging to the
same family—has enormously-developed mandibles (fig. 23); he is bold
and pugnacious; when threatened on any side he faces round, opening his
great jaws, and at the same time stridulating loudly; but the mandibles
were not strong enough to pinch my finger so as to cause actual pain.

[Illustration: Fig. 23. Chiasognathus grantii, reduced. Upper figure,
male; lower figure, female.]

Sexual selection, which implies the possession of considerable
perceptive powers and of strong passions, seems to have been more
effective with the Lamellicorns than with any other family of the
Coleoptera or beetles. With some species the males are provided with
weapons for fighting; some live in pairs and show mutual affection;
many have the power of stridulating when excited; many are furnished
with the most extraordinary horns, apparently for the sake of ornament;
some which are diurnal in their habits are gorgeously coloured; and,
lastly, several of the largest beetles in the world belong to this
family, which was placed by Linnæus and Fabricius at the head of the
Order of the Coleoptera.[493]

_Stridulating organs._—Beetles belonging to many and widely distinct
families possess these organs. The sound can sometimes be heard at the
distance of several feet or even yards,[494] but is not comparable with
that produced by the Orthoptera. The part which may be called the rasp
generally consists of a narrow slightly-raised surface, crossed by very
fine, parallel ribs, sometimes so fine as to cause iridescent colours,
and having a very elegant appearance under the microscope. In some
cases, for instance, with Typhæus, it could be plainly seen that
extremely minute, bristly, scale-like prominences, which cover the whole
surrounding surface in approximately parallel lines, give rise to the
ribs of the rasp by becoming confluent and straight, and at the same
time more prominent and smooth. A hard ridge on any adjoining part of
the body, which in some cases is specially modified for the purpose,
serves as the scraper for the rasp. The scraper is rapidly moved across
the rasp, or conversely the rasp across the scraper.

[Illustration: Fig. 24. Necrophorus (from Landois). _r._ The two rasps.
Left-hand figure, part of the rasp highly magnified.]

These organs are situated in widely different positions. In the
carrion-beetles (Necrophorus) two parallel rasps (_r_, fig. 24) stand on
the dorsal surface of the fifth abdominal segment, each rasp being
crossed, as described by Landois,[495] by from 126 to 140 fine ribs.
These ribs are scraped by the posterior margins of the elytra, a small
portion of which projects beyond the general outline. In many
Crioceridæ, and in _Clythra 4-punctata_ (one of the Chrysomelidæ), and
in some Tenebrionidæ, &c.,[496] the rasp is seated on the dorsal apex of
the abdomen, on the pygidium or pro-pygidium, and is scraped as above by
the elytra. In Heterocerus, which belongs to another family, the rasps
are placed on the sides of the first abdominal segment, and are scraped
by ridges on the femora.[497] In certain Curculionidæ and Carabidæ,[498]
the parts are completely reversed in position, for the rasps are seated
on the inferior surface of the elytra, near their apices, or along their
outer margins, and the edges of the abdominal segments serve as the
scrapers. In _Pelobius hermanni_ (one of Dytiscidæ or water-beetles) a
strong ridge runs parallel and near to the sutural margin of the elytra,
and is crossed by ribs, coarse in the middle part, but becoming
gradually finer at both ends, especially at the upper end; when this
insect is held under water or in the air, a stridulating noise is
produced by scraping the extreme horny margin of the abdomen against the
rasp. In a great number of long-horned beetles (Longicornia) the organs
are altogether differently situated, the rasp being on the meso-thorax,
which is rubbed against the pro-thorax; Landois counted 238 very fine
ribs on the rasp of _Cerambyx heros_.

[Illustration: Fig. 25. Hind-leg of Geotrupes stercorarius (from
Landois). _r._ Rasp. _c._ Coxa. _f._ Femur. _t._ Tibia. _tr._ Tarsi.]

Many Lamellicorns have the power of stridulating, and the organs differ
greatly in position. Some species stridulate very loudly, so that when
Mr. F. Smith caught a _Trox sabulosus_, a gamekeeper who stood by
thought that he had caught a mouse; but I failed to discover the proper
organs in this beetle. In Geotrupes and Typhæus a narrow ridge runs
obliquely across (_r_, fig. 25) the coxa of each hind-leg, having in
_G. stercorarius_ 84 ribs, which are scraped by a specially-projecting
part of one of the abdominal segments. In the nearly allied _Copris
lunaris_, an excessively narrow fine rasp runs along the sutural margin
of the elytra, with another short rasp near the basal outer margin; but
in some other Coprini the rasp is seated, according to Leconte,[499] on
the dorsal surface of the abdomen. In Oryctes it is seated on the
pro-pygidium, and in some other Dynastini, according to the same
entomologist, on the under surface of the elytra. Lastly, Westring
states that in _Omaloplia brunnea_ the rasp is placed on the
pro-sternum, and the scraper on the meta-sternum, the parts thus
occupying the under surface of the body, instead of the upper surface as
in the Longicorns.

We thus see that the stridulating organs in the different coleopterous
families are wonderfully diversified in position, but not much in
structure. Within the same family some species are provided with these
organs, and some are quite destitute of them. This diversity is
intelligible, if we suppose that originally various species made a
shuffling or hissing noise by the rubbing together of the hard and rough
parts of their bodies which were in contact; and that from the noise
thus produced being in some way useful, the rough surfaces were
gradually developed into regular stridulating organs. Some beetles as
they move, now produce, either intentionally or unintentionally, a
shuffling noise, without possessing any proper organs for the purpose.
Mr. Wallace informs me that the _Euchirus longimanus_ (a Lamellicorn,
with the anterior legs wonderfully elongated in the male) “makes, whilst
moving, a low hissing sound by the protrusion and contraction of the
abdomen; and when seized it produces a grating sound by rubbing its
hind-legs against the edges of the elytra.” The hissing sound is clearly
due to a narrow rasp running along the sutural margin of each elytron;
and I could likewise make the grating sound by rubbing the shagreened
surface of the femur against the granulated margin of the corresponding
elytron; but I could not here detect any proper rasp; nor is it likely
that I could have overlooked it in so large an insect. After examining
Cychrus and reading what Westring has written in his two papers about
this beetle, it seems very doubtful whether it possesses any true rasp,
though it has the power of emitting a sound.

From the analogy of the Orthoptera and Homoptera, I expected to find
that the stridulating organs in the Coleoptera differed according to
sex; but Landois, who has carefully examined several species, observed
no such difference; nor did Westring; nor did Mr. G. R. Crotch in
preparing the numerous specimens which he had the kindness to send me
for examination. Any slight sexual difference, however, would be
difficult to detect, on account of the great variability of these
organs. Thus in the first pair of the _Necrophorus humator_ and of the
_Pelobius_ which I examined, the rasp was considerably larger in the
male than in the female; but not so with succeeding specimens. In
_Geotrupes stercorarius_ the rasp appeared to me thicker, opaquer, and
more prominent in three males than in the same number of females;
consequently my son, Mr. F. Darwin, in order to discover whether the
sexes differed in their power of stridulating, collected 57 living
specimens, which he separated into two lots, according as they made,
when held in the same manner, a greater or lesser noise. He then
examined their sexes, but found that the males were very nearly in the
same proportion to the females in both lots. Mr. F. Smith has kept alive
numerous specimens of _Mononychus pseudacori_ (Curculionidæ), and is
satisfied that both sexes stridulate, and apparently in an equal degree.

Nevertheless the power of stridulating is certainly a sexual character
in some few Coleoptera. Mr. Crotch has discovered that the males alone
of two species of Heliopathes (Tenebrionidæ) possess stridulating
organs. I examined five males of _H. gibbus_, and in all these there was
a well-developed rasp, partially divided into two, on the dorsal surface
of the terminal abdominal segment; whilst in the same number of females
there was not even a rudiment of the rasp, the membrane of this segment
being transparent and much thinner than in the male. In _H.
cribratostriatus_ the male has a similar rasp, excepting that it is not
partially divided into two portions, and the female is completely
destitute of this organ; but in addition the male has on the apical
margins of the elytra, on each side of the suture, three or four short
longitudinal ridges, which are crossed by extremely fine ribs, parallel
to and resembling those on the abdominal rasp; whether these ridges
serve as an independent rasp, or as a scraper for the abdominal rasp, I
could not decide: the female exhibits no trace of this latter structure.

Again, in three species of the Lamellicorn genus Oryctes, we have a
nearly parallel case. In the females of _O. gryphus_ and _nasicornis_
the ribs on the rasp of the pro-pygidium are less continuous and less
distinct than in the males; but the chief difference is that the whole
upper surface of this segment, when held in the proper light, is seen to
be clothed with hairs, which are absent or are represented by
excessively fine down in the males. It should be noticed that in all
Coleoptera the effective part of the rasp is destitute of hairs. In _O.
senegalensis_ the difference between the sexes is more strongly marked,
and this is best seen when the proper segment is cleaned and viewed as a
transparent object. In the female the whole surface is covered with
little separate crests, bearing spines; whilst in the male these crests
become, in proceeding towards the apex, more and more confluent,
regular, and naked; so that three-fourths of the segment is covered with
extremely fine parallel ribs, which are quite absent in the female. In
the females, however, of all three species of Oryctes, when the abdomen
of a softened specimen is pushed backwards and forwards, a slight
grating or stridulating sound can be produced.

In the case of the Heliopathes and Oryctes there can hardly be a doubt
that the males stridulate in order to call or to excite the females; but
with most beetles the stridulation apparently serves both sexes as a
mutual call. This view is not rendered improbable from beetles
stridulating under various emotions; we know that birds use their voices
for many purposes besides singing to their mates. The great
Chiasognathus stridulates in anger or defiance; many species do the same
from distress or fear, when held so that they cannot escape; Messrs.
Wollaston and Crotch were able, by striking the hollow stems of trees in
the Canary Islands, to discover the presence of beetles belonging to the
genus Acalles by their stridulation. Lastly the male Ateuchus
stridulates to encourage the female in her work, and from distress when
she is removed.[500] Some naturalists believe that beetles make this
noise to frighten away their enemies; but I cannot think that the
quadrupeds and birds which are able to devour the larger beetles with
their extremely hard coats, would be frightened by so slight a grating
sound. The belief that the stridulation serves as a sexual call is
supported by the fact that death-ticks (_Anobium tessellatum_) are well
known to answer each other’s ticking, or, as I have myself observed, a
tapping noise artificially made; and Mr. Doubleday informs me that he
has twice or thrice observed a female ticking,[501] and in the course of
an hour or two has found her united with a male, and on one occasion
surrounded by several males. Finally, it seems probable that the two
sexes of many kinds of beetles were at first enabled to find each other
by the slight shuffling noise produced by the rubbing together of the
adjoining parts of their hard bodies; and that as the males or females
which made the greatest noise succeeded best in finding partners, the
rugosities on various parts of their bodies were gradually developed by
means of sexual selection into true stridulating organs.



  Courtship of butterflies—Battles—Ticking noise—Colours
  common to both sexes, or more brilliant in the
  males—Examples—Not due to the direct action of the conditions
  of life—Colours adapted for protection—Colours of
  moths—Display—Perceptive powers of the
  Lepidoptera—Variability—Causes of the difference in colour
  between the males and females—Mimickry, female butterflies
  more brilliantly coloured than the males—Bright colours of
  caterpillars—Summary and concluding remarks on the secondary
  sexual characters of insects—Birds and insects compared.

In this great Order the most interesting point for us is the difference
in colour between the sexes of the same species, and between the
distinct species of the same genus. Nearly the whole of the following
chapter will be devoted to this subject; but I will first make a few
remarks on one or two other points. Several males may often be seen
pursuing and crowding round the same female. Their courtship appears to
be a prolonged affair, for I have frequently watched one or more males
pirouetting round a female until I became tired, without seeing the end
of the courtship. Although butterflies are such weak and fragile
creatures, they are pugnacious, and an Emperor butterfly[502] has been
captured with the tips of its wings broken from a conflict with another
male. Mr. Collingwood in speaking of the frequent battles between the
butterflies of Borneo says, “They whirl round each other with the
greatest rapidity, and appear to be incited by the greatest ferocity.”
One case is known of a butterfly, namely the _Ageronia feronia_, which
makes a noise like that produced by a toothed wheel passing under a
spring catch, and which could be heard at the distance of several yards.
At Rio de Janeiro this sound was noticed by me, only when two were
chasing each other in an irregular course, so that it is probably made
during the courtship of the sexes; but I neglected to attend to this

Every one has admired the extreme beauty of many butterflies and of some
moths; and we are led to ask, how has this beauty been acquired? Have
their colours and diversified patterns simply resulted from the direct
action of the physical conditions to which these insects have been
exposed, without any benefit being thus derived? Or have successive
variations been accumulated and determined either as a protection or for
some unknown purpose, or that one sex might be rendered attractive to
the other? And, again, what is the meaning of the colours being widely
different in the males and females of certain species, and alike in the
two sexes of other species? Before attempting to answer these questions
a body of facts must be given.

With most of our English butterflies, both those which are beautiful,
such as the admiral, peacock, and painted lady (Vanessæ), and those
which are plain-coloured, such as the meadow-browns (Hipparchiæ), the
sexes are alike. This is also the case with the magnificent Heliconidæ
and Danaidæ of the tropics. But in certain other tropical groups, and
with some of our English butterflies, as the purple emperor, orange-tip,
&c. (_Apatura Iris_ and _Anthocharis cardamines_), the sexes differ
either greatly or slightly in colour. No language suffices to describe
the splendour of the males of some tropical species. Even within the
same genus we often find species presenting an extraordinary difference
between the sexes, whilst others have their sexes closely alike. Thus in
the South American genus Epicalia, Mr. Bates, to whom I am much indebted
for most of the following facts and for looking over this whole
discussion, informs me that he knows twelve species, the two sexes of
which haunt the same stations (and this is not always the case with
butterflies), and therefore cannot have been differently affected by
external conditions[504]. In nine of these species the males rank
amongst the most brilliant of all butterflies, and differ so greatly
from the comparatively plain females that they were formerly placed in
distinct genera. The females of these nine species resemble each other
in their general type of coloration, and likewise resemble both sexes in
several allied genera, found in various parts of the world. Hence in
accordance with the descent-theory we may infer that these nine species,
and probably all the others of the genus, are descended from an
ancestral form which was coloured in nearly the same manner. In the
tenth species the female still retains the same general colouring, but
the male resembles her, so that he is coloured in a much less gaudy and
contrasted manner than the males of the previous species. In the
eleventh and twelfth species, the females depart from the type of
colouring which is usual with their sex in this genus, for they are
gaily decorated in nearly the same manner as the males, but in a
somewhat less degree. Hence in these two species the bright colours of
the males seem to have been transferred to the females; whilst the male
of the tenth species has either retained or recovered the plain colours
of the female as well as of the parent-form of the genus; the two sexes
being thus rendered in both cases, though in an opposite manner, nearly
alike. In the allied genus Eubagis, both sexes of some of the species
are plain-coloured and nearly alike; whilst with the greater number the
males are decorated with beautiful metallic tints, in a diversified
manner, and differ much from their females. The females throughout the
genus retain the same general style of colouring, so that they commonly
resemble each other much more closely than they resemble their own
proper males.

In the genus Papilio, all the species of the Æneas group are remarkable
for their conspicuous and strongly contrasted colours, and they
illustrate the frequent tendency to gradation in the amount of
difference between the sexes. In a few species, for instance in _P.
ascanius_, the males and females are alike; in others the males are a
little or very much more superbly coloured than the females. The genus
Junonia allied to our Vanessæ offers a nearly parallel case, for
although the sexes of most of the species resemble each other and are
destitute of rich colours, yet in certain species, as in _J. œnone_,
the male is rather more brightly coloured than the female, and in a few
(for instance _J. andremiaja_) the male is so different from the female
that he might be mistaken for an entirely distinct species.

Another striking case was pointed out to me in the British museum by Mr.
A. Butler, namely one of the Tropical American Theclæ, in which both
sexes are nearly alike and wonderfully splendid; in another, the male
is coloured in a similarly gorgeous manner, whilst the whole upper
surface of the female is of a dull uniform brown. Our common little
English blue butterflies of the genus Lycæna, illustrate the various
differences in colour between the sexes, almost as well, though not in
so striking a manner, as the above exotic genera. In _Lycæna agestis_
both sexes have wings of a brown colour, bordered with small ocellated
orange spots, and are consequently alike. In _L. œgon_ the wings of
the male are of a fine blue, bordered with black; whilst the wings of
the female are brown, with a similar border, and closely resemble those
of _L. agestis_. Lastly, in _L. arion_ both sexes are of a blue colour
and nearly alike, though in the female the edges of the wings are rather
duskier, with the black spots plainer; and in a bright blue Indian
species both sexes are still more closely alike.

I have given the foregoing cases in some detail in order to shew, in the
first place, that when the sexes of butterflies differ, the male as a
general rule is the most beautiful, and departs most from the usual type
of colouring of the group to which the species belongs. Hence in most
groups the females of the several species resemble each other much more
closely than do the males. In some exceptional cases, however, to which
I shall hereafter allude, the females are coloured more splendidly than
the males. In the second place these cases have been given to bring
clearly before the mind that within the same genus, the two sexes
frequently present every gradation from no difference in colour to so
great a difference that it was long before the two were placed by
entomologists in the same genus. In the third place, we have seen that
when the sexes nearly resemble each other, this apparently may be due
either to the male having transferred his colours to the female, or to
the male having retained, or perhaps recovered, the primordial colours
of the genus to which the species belongs. It also deserves notice that
in those groups in which the sexes present any difference of colour, the
females usually resemble the males to a certain extent, so that when the
males are beautiful to an extraordinary degree, the females almost
invariably exhibit some degree of beauty. From the numerous cases of
gradation in the amount of difference between the sexes, and from the
prevalence of the same general type of coloration throughout the whole
of the same group, we may conclude that the causes, whatever they may
be, which have determined the brilliant colouring of the males alone of
some species, and of both sexes in a more or less equal degree of other
species, have generally been the same.

As so many gorgeous butterflies inhabit the tropics, it has often been
supposed that they owe their colours to the great heat and moisture of
these zones; but Mr. Bates[505] has shewn by the comparison of various
closely-allied groups of insects from the temperate and tropical
regions, that this view cannot be maintained; and the evidence becomes
conclusive when brilliantly-coloured males and plain-coloured females of
the same species inhabit the same district, feed on the same food, and
follow exactly the same habits of life. Even when the sexes resemble
each other, we can hardly believe that their brilliant and
beautifully-arranged colours are the purposeless result of the nature of
the tissues, and the action of the surrounding conditions.

With animals of all kinds, whenever colour has been modified for some
special purpose, this has been, as far as we can judge, either for
protection or as an attraction between the sexes. With many species of
butterflies the upper surfaces of the wings are obscurely coloured, and
this in all probability leads to their escaping observation and danger.
But butterflies when at rest would be particularly liable to be attacked
by their enemies; and almost all the kinds when resting raise their
wings vertically over their backs, so that the lower sides alone are
exposed to view. Hence it is this side which in many cases is obviously
coloured so as to imitate the surfaces on which these insects commonly
rest. Dr. Rössler, I believe, first noticed the similarity of the closed
wings of certain Vanessæ and other butterflies to the bark of trees.
Many analogous and striking facts could be given. The most interesting
one is that recorded by Mr. Wallace[506] of a common Indian and Sumatran
butterfly (Kallima), which disappears like magic when it settles in a
bush; for it hides its head and antennæ between its closed wings, and
these in form, colour, and veining cannot be distinguished from a
withered leaf together with the footstalk. In some other cases the lower
surfaces of the wings are brilliantly coloured, and yet are protective;
thus in _Thecla rubi_ the wings when closed are of an emerald green and
resemble the young leaves of the bramble, on which this butterfly in the
spring may often be seen seated.

Although the obscure tints of the upper or under surface of many
butterflies no doubt serve to conceal them, yet we cannot possibly
extend this view to the brilliant and conspicuous colours of many kinds,
such as our admiral and peacock Vanessæ, our white cabbage-butterflies
(Pieris), or the great swallow-tail Papilio which haunts the open
fens—for these butterflies are thus rendered visible to every living
creature. With these species both sexes are alike; but in the common
brimstone butterfly (_Gonepteryx rhamni_), the male is of an intense
yellow, whilst the female is much paler; and in the orange-tip
(_Anthocharis cardamines_) the males alone have the bright orange tips
to their wings. In these cases the males and females are equally
conspicuous, and it is not credible that their difference in colour
stands in any relation to ordinary protection. Nevertheless it is
possible that the conspicuous colours of many species may be in an
indirect manner beneficial, as will hereafter be explained, by leading
their enemies at once to recognise them as unpalatable. Even in this
case it does not certainly follow that their bright colours and
beautiful patterns were acquired for this special purpose. In some other
remarkable cases, beauty has been gained for the sake of protection,
through the imitation of other beautiful species, which inhabit the same
district and enjoy an immunity from attack by being in some way
offensive to their enemies.

The female of our orange-tip butterfly, above referred to, and of an
American species (_Anth. genutia_) probably shew us, as Mr. Walsh has
remarked to me, the primordial colours of the parent-species of the
genus; for both sexes of four or five widely-distributed species are
coloured in nearly the same manner. We may infer here, as in several
previous cases, that it is the males of _Anth. cardamines_ and _genutia_
which have departed from the usual type of colouring of their genus. In
the _Anth. sara_ from California, the orange-tips have become partially
developed in the female; for her wings are tipped with reddish-orange,
but paler than in the male, and slightly different in some other
respects. In an allied Indian form, the _Iphias glaucippe_, the
orange-tips are fully developed in both sexes. In this Iphias the under
surface of the wings marvellously resembles, as pointed out to me by Mr.
A. Butler, a pale-coloured leaf; and in our English orange-tip, the
under surface resembles the flower-head of the wild parsley, on which it
may be seen going to rest at night.[507] The same reasoning power which
compels us to believe that the lower surfaces have here been coloured
for the sake of protection, leads us to deny that the wings have been
tipped, especially when this character is confined to the males, with
bright orange for the same purpose.

Turning now to Moths: most of these rest motionless with their wings
depressed during the whole or greater part of the day; and the upper
surfaces of their wings are often shaded and coloured in an admirable
manner, as Mr. Wallace has remarked, for escaping detection. With most
of the Bombycidæ and Noctuidæ,[508] when at rest, the front-wings
overlap and conceal the hind-wings; so that the latter might be brightly
coloured without much risk; and they are thus coloured in many species
of both families. During the act of flight, moths would often be able to
escape from their enemies; nevertheless, as the hind-wings are then
fully exposed to view, their bright colours must generally have been
acquired at the cost of some little risk. But the following fact shews
us how cautious we ought to be in drawing conclusions on this head. The
common yellow under-wings (Triphaena) often fly about during the day or
early evening, and are then conspicuous from the colour of their
hind-wings. It would naturally be thought that this would be a source of
danger; but Mr. J. Jenner Weir believes that it actually serves them as
a means of escape, for birds strike at these brightly coloured and
fragile surfaces, instead of at the body. For instance, Mr. Weir turned
into his aviary a vigorous specimen of _Triphaena pronuba_, which was
instantly pursued by a robin; but the bird’s attention being caught by
the coloured wings, the moth was not captured until after about fifty
attempts, and small portions of the wings were repeatedly broken off. He
tried the same experiment, in the open air, with a _T. fimbria_ and
swallow; but the large size of this moth probably interfered with its
capture.[509] We are thus reminded of a statement made by Mr.
Wallace,[510] namely, that in the Brazilian forests and Malayan islands,
many common and highly-decorated butterflies are weak flyers, though
furnished with a broad expanse of wings; and they “are often captured
with pierced and broken wings, as if they had been seized by birds, from
which they had escaped: if the wings had been much smaller in proportion
to the body, it seems probable that the insect would more frequently
have been struck or pierced in a vital part, and thus the increased
expanse of the wings may have been indirectly beneficial.”

_Display._—The bright colours of butterflies and of some moths are
specially arranged for display, whether or not they serve in addition as
a protection. Bright colours would not be visible during the night; and
there can be no doubt that moths, taken as a body, are much less gaily
decorated than butterflies, all of which are diurnal in their habits.
But the moths in certain families, such as the Zygænidæ, various
Sphingidæ, Uraniidæ, some Arctiidæ and Saturniidæ, fly about during the
day or early evening, and many of these are extremely beautiful, being
far more brightly coloured than the strictly nocturnal kinds. A few
exceptional cases, however, of brightly-coloured nocturnal species have
been recorded.[511]

There is evidence of another kind in regard to display. Butterflies, as
before remarked, elevate their wings when at rest, and whilst basking in
the sunshine often alternately raise and depress them, thus exposing to
full view both surfaces; and although the lower surface is often
coloured in an obscure manner as a protection, yet in many species it is
as highly coloured as the upper surface, and sometimes in a very
different manner. In some tropical species the lower surface is even
more brilliantly coloured than the upper.[512] In one English
fritillary, the _Argynnis aglaia_, the lower surface alone is ornamented
with shining silver discs. Nevertheless, as a general rule, the upper
surface, which is probably the most fully exposed, is coloured more
brightly and in a more diversified manner than the lower. Hence the
lower surface generally affords to entomologists the most useful
character for detecting the affinities of the various species.

Now if we turn to the enormous group of moths, which do not habitually
expose to full view the under surface of their wings, this side is very
rarely, as I hear from Mr. Stainton, coloured more brightly than the
upper side, or even with equal brightness. Some exceptions to the rule,
either real or apparent, must be noticed, as that of Hypopyra, specified
by Mr. Wormald.[513] Mr. R. Trimen informs me that in Guenée’s great
work, three moths are figured, in which the under surface is much the
most brilliant. For instance, in the Australian Gastrophora the upper
surface of the fore-wing is pale greyish-ochreous, while the lower
surface is magnificently ornamented by an ocellus of cobalt-blue, placed
in the midst of a black mark, surrounded by orange-yellow, and this by
bluish-white. But the habits of these three moths are unknown; so that
no explanation can be given of their unusual style of colouring. Mr.
Trimen also informs me that the lower surface of the wings in certain
other Geometræ[514] and quadrifid Noctuæ are either more variegated or
more brightly-coloured than the upper surface; but some of these species
have the habit of “holding their wings quite erect over their backs,
retaining them in this position for a considerable time,” and thus
exposing to view the under surface. Other species when settled on the
ground or herbage have the habit of now and then suddenly and slightly
lifting up their wings. Hence the lower surface of the wings being more
brightly-coloured than the upper surface in certain moths is not so
anomalous a circumstance as it at first appears. The Saturniidæ include
some of the most beautiful of all moths, their wings being decorated, as
in our British Emperor moth, with fine ocelli; and Mr. T. W. Wood[515]
observes that they resemble butterflies in some of their movements; “for
instance, in the gentle waving up and down of the wings, as if for
display, which is more characteristic of diurnal than of nocturnal

It is a singular fact that no British moths, nor as far as I can
discover hardly any foreign species, which are brilliantly coloured,
differ much in colour according to sex; though this is the case with
many brilliant butterflies. The male, however, of one American moth, the
_Saturnia Io_, is described as having its fore-wings deep yellow,
curiously marked with purplish-red spots; whilst the wings of the female
are purple-brown, marked with grey lines.[516] The British moths which
differ sexually in colour are all brown, or various tints of dull
yellow, or nearly white. In several species the males are much darker
than the females,[517] and these belong to groups which generally fly
about during the afternoon. On the other hand, in many genera, as Mr.
Stainton informs me, the males have the hind-wings whiter than those of
the female—of which, fact _Agrotis exclamationis_ offers a good
instance. The males are thus rendered more conspicuous than the females,
whilst flying about in the dusk. In the Ghost Moth (_Hepialus humuli_)
the difference is more strongly marked; the males being white and the
females yellow with darker markings. It is difficult to conjecture what
the meaning can be of these differences between the sexes in the shades
of darkness or lightness; but we can hardly suppose that they are the
result of mere variability with sexually-limited inheritance,
independently of any benefit thus derived.

From the foregoing statements it is impossible to admit that the
brilliant colours of butterflies and of some few moths, have commonly
been acquired for the sake of protection. We have seen that their
colours and elegant patterns are arranged and exhibited as if for
display. Hence I am led to suppose that the females generally prefer, or
are most excited by the more brilliant males; for on any other
supposition the males would be ornamented, as far as we can see, for no
purpose. We know that ants and certain lamellicorn beetles are capable
of feeling an attachment for each other, and that ants recognise their
fellows after an interval of several months. Hence there is no abstract
improbability in the Lepidoptera, which probably stand nearly or quite
as high in the scale as these insects, having sufficient mental capacity
to admire bright colours. They certainly discover flowers by colour,
and, as I have elsewhere shewn, the plants which are fertilised
exclusively by the wind never have a conspicuously-coloured corolla. The
Humming-bird Sphinx may often be seen to swoop down from a distance on a
bunch of flowers in the midst of green foliage; and I have been assured
by a friend, that these moths repeatedly visited flowers painted on the
walls of a room in the South of France. The common white butterfly, as I
hear from Mr. Doubleday, often flies down to a bit of paper on the
ground, no doubt mistaking it for one of its own species. Mr.
Collingwood[518] in speaking of the difficulty of collecting certain
butterflies in the Malay Archipelago, states that “a dead specimen
pinned upon a conspicuous twig will often arrest an insect of the same
species in its headlong flight, and bring it down within easy reach of
the net, especially if it be of the opposite sex.”

The courtship of butterflies is a prolonged affair. The males sometimes
fight together in rivalry; and many may be seen pursuing or crowding
round the same female. If, then, the females do not prefer one male to
another, the pairing must be left to mere chance, and this does not
appear to me a probable event. If, on the other hand, the females
habitually, or even occasionally, prefer the more beautiful males, the
colours of the latter will have been rendered brighter by degrees, and
will have been transmitted to both sexes or to one sex, according to
which law of inheritance prevailed. The process of sexual selection will
have been much facilitated, if the conclusions arrived at from various
kinds of evidence in the supplement to the ninth chapter can be trusted;
namely that the males of many Lepidoptera, at least in the imago state,
greatly exceed in number the females.

Some facts, however, are opposed to the belief that female butterflies
prefer the more beautiful males; thus, as I have been assured by several
observers, fresh females may frequently be seen paired with battered,
faded or dingy males; but this is a circumstance which could hardly
fail often to follow from the males emerging from their cocoons earlier
than the females. With moths of the family of the Bombycidæ, the sexes
pair immediately after assuming the imago state; for they cannot feed,
owing to the rudimentary condition of their mouths. The females, as
several entomologists have remarked to me, lie in an almost torpid
state, and appear not to evince the least choice in regard to their
partners, This is the case with the common silk-moth (_B. mori_), as I
have been told by some continental and English breeders. Dr. Wallace,
who has had such immense experience in breeding _Bombyx cynthia_, is
convinced that the females evince no choice or preference. He has kept
above 300 of these moths living together, and has often found the most
vigorous females mated with stunted males. The reverse apparently seldom
occurs; for, as he believes, the more vigorous males pass over the
weakly females, being attracted by those endowed with most vitality.
Although we have been indirectly induced to believe that the females of
many species prefer the more beautiful males, I have no reason to
suspect, either with moths or butterflies, that the males are attracted
by the beauty of the females. If the more beautiful females had been
continually preferred, it is almost certain, from the colours of
butterflies being so frequently transmitted to one sex alone, that the
females would often have been rendered more beautiful than their male
partners. But this does not occur except in a few instances; and these
can be explained, as we shall presently see, on the principle of
mimickry and protection.

As sexual selection primarily depends on variability, a few words must
be added on this subject. In respect to colour there is no difficulty,
as any number of highly variable Lepidoptera could be named. One good
instance will suffice. Mr. Bates shewed me a whole series of specimens
of _Papilio sesostris_ and _childrenæ_; in the latter the males varied
much in the extent of the beautifully enamelled green patch on the
fore-wings, and in the size of the white mark, as well as of the
splendid crimson stripe on the hind-wings; so that there was a great
contrast between the most and least gaudy males. The male of _Papilio
sesostris_, though a beautiful insect, is much less so than _P.
childrenæ_. It likewise varies a little in the size of the green patch
on the fore-wings, and in the occasional appearance of a small crimson
stripe on the hind-wings, borrowed, as it would seem, from its own
female; for the females of this and of many other species in the Æneas
group possess this crimson stripe. Hence between the brightest specimens
of _P. sesostris_ and the least bright of _P. childrenæ_, there was but
a small interval; and it was evident that as far as mere variability is
concerned, there would be no difficulty in permanently increasing by
means of selection the beauty of either species. The variability is here
almost confined to the male sex; but Mr. Wallace and Mr. Bates have
shewn[519] that the females of some other species are extremely
variable, the males being nearly constant. As I have before mentioned
the Ghost Moth (_Hepialus humuli_) as one of the best instances in
Britain of a difference in colour between the sexes of moths, it may be
worth adding[520] that in the Shetland Islands, males are frequently
found which closely resemble the females. In a future chapter I shall
have occasion to shew that the beautiful eye-like spots or ocelli, so
common on the wings of many Lepidoptera, are eminently variable.

On the whole, although many serious objections may be urged, it seems
probable that most of the species of Lepidoptera which are brilliantly
coloured, owe their colours to sexual selection, excepting in certain
cases, presently to be mentioned, in which conspicuous colours are
beneficial as a protection. From the ardour of the male throughout the
animal kingdom, he is generally willing to accept any female; and it is
the female which usually exerts a choice. Hence if sexual selection has
here acted, the male, when the sexes differ, ought to be the most
brilliantly coloured; and this undoubtedly is the ordinary rule. When
the sexes are brilliantly coloured and resemble each other, the
characters acquired by the males appear to have been transmitted to both
sexes. But will this explanation of the similarity and dissimilarity in
colour between the sexes suffice?

The males and females of the same species of butterfly are known[521] in
several cases to inhabit different stations, the former commonly basking
in the sunshine, the latter haunting gloomy forests. It is therefore
possible that different conditions of life may have acted directly on
the two sexes; but this is not probable,[522] as in the adult state they
are exposed during a very short period to different conditions; and the
larvæ of both are exposed to the same conditions. Mr. Wallace believes
that the less brilliant colours of the female have been specially
gained in all or almost all cases for the sake of protection. On the
contrary it seems to me more probable that the males alone, in the large
majority of cases, have acquired their bright colours through sexual
selection, the females having been but little modified. Consequently the
females of distinct but allied species ought to resemble each other much
more closely than do the males of the same species; and this is the
general rule. The females thus approximately show us the primordial
colouring of the parent-species of the group to which they belong. They
have, however, almost always been modified to a certain extent by some
of the successive steps of variation, through the accumulation of which
the males were rendered beautiful, having been transferred to them. The
males and females of allied though distinct species will also generally
have been exposed during their prolonged larval state to different
conditions, and may have been thus indirectly affected; though with the
males any slight change of colour thus caused will often have been
completely masked by the brilliant tints gained through sexual
selection. When we treat of Birds, I shall have to discuss the whole
question whether the differences in colour between the males and females
have been in part specially gained by the latter as a protection; so
that I will here only give unavoidable details.

In all cases when the more common form of equal inheritance by both
sexes has prevailed, the selection of bright-coloured males would tend
to make the females bright-coloured; and the selection of dull-coloured
females would tend to make the males dull. If both processes were
carried on simultaneously, they would tend to neutralise each other. As
far as I can see, it would be extremely difficult to change through
selection the one form of inheritance into the other. But by the
selection of successive variations, which were from the first sexually
limited in their transmission, there would not be the slightest
difficulty in giving bright colours to the males alone, and at the same
time or subsequently, dull colours to the females alone. In this latter
manner female butterflies and moths may, as I fully admit, have been
rendered inconspicuous for the sake of protection, and widely different
from their males.

Mr. Wallace[523] has argued with much force in favour of his view that
when the sexes differ, the female has been specially modified for the
sake of protection; and that this has been effected by one form of
inheritance, namely, the transmission of characters to both sexes,
having been changed through the agency of natural selection into the
other form, namely, transmission to one sex. I was at first strongly
inclined to accept this view; but the more I have studied the various
classes throughout the animal kingdom, the less probable it has
appeared. Mr. Wallace urges that both sexes of the _Heliconidæ_,
_Danaidæ_, _Acroeidæ_ are equally brilliant because both are protected
from the attacks of birds and other enemies, by their offensive odour;
but that in other groups, which do not possess this immunity, the
females have been rendered inconspicuous, from having more need of
protection than the males. This supposed difference in the “need of
protection by the two sexes” is rather deceptive, and requires some
discussion. It is obvious that brightly-coloured individuals, whether
males or females, would equally attract, and obscurely-coloured
individuals equally escape, the attention of their enemies. But we are
concerned with the effects of the destruction or preservation of certain
individuals of either sex, on the character of the race. With insects,
after the male has fertilised the female, and after the latter has laid
her eggs, the greater or less immunity from danger of either sex could
not possibly have any effect on the offspring. Before the sexes have
performed their proper functions, if they existed in equal numbers and
if they strictly paired (all other circumstances being the same), the
preservation of the males and females would be equally important for the
existence of the species and for the character of the offspring. But
with most animals, as is known to be the case with the domestic
silk-moth, the male can fertilise two or three females; so that the
destruction of the males would not be so injurious to the species as
that of the females. On the other hand, Dr. Wallace believes that with
moths the progeny from a second or third fertilisation is apt to be
weakly, and therefore would not have so good chance of surviving. When
the males exist in much greater numbers than the females, no doubt many
males might be destroyed with impunity to the species; but I cannot see
that the results of ordinary selection for the sake of protection would
be influenced by the sexes existing in unequal numbers; for the same
proportion of the more conspicuous individuals, whether males or
females, would probably be destroyed. If indeed the males presented a
greater range of variation in colour, the result would be different; but
we need not here follow out such complex details. On the whole I cannot
perceive that an inequality in the numbers of the two sexes would
influence in any marked manner the effects of ordinary selection on the
character of the offspring.

Female Lepidoptera require, as Mr. Wallace insists, some days to
deposit their fertilised ova and to search for a proper place; during
this period (whilst the life of the male was of no importance) the
brighter-coloured females would be exposed to danger and would be liable
to be destroyed. The duller-coloured females on the other hand would
survive, and thus would influence, it might be thought, in a marked
manner the character of the species,—either of both sexes or of one
sex, according to which form of inheritance prevailed. But it must not
be forgotten that the males emerge from the cocoon-state some days
before the females, and during this period, whilst the unborn females
were safe, the brighter-coloured males would be exposed to danger; so
that ultimately both sexes would probably be exposed during a nearly
equal length of time to danger, and the elimination of conspicuous
colours would not be much more effective in the one than the other sex.

It is a more important consideration that female Lepidoptera, as Mr.
Wallace remarks, and as is known to every collector, are generally
slower flyers than the males. Consequently the latter, if exposed to
greater danger from being conspicuously coloured, might be able to
escape from their enemies, whilst the similarly-coloured females would
be destroyed; and thus the females would have the most influence in
modifying the colour of their progeny.

There is one other consideration: bright colours, as far as sexual
selection is concerned, are commonly of no service to the females; so
that if the latter varied in brightness, and the variations were
sexually limited in their transmission, it would depend on mere chance
whether the females had their bright colours increased; and this would
tend throughout the Order to diminish the number of species with
brightly-coloured females in comparison with the species having
brightly-coloured males. On the other hand, as bright colours are
supposed to be highly serviceable to the males in their love-struggles,
the brighter males (as we shall see in the chapter on Birds) although
exposed to rather greater danger, would on an average procreate a
greater number of offspring than the duller males. In this case, if the
variations were limited in their transmission to the male sex, the males
alone would be rendered more brilliantly coloured; but if the variations
were not thus limited, the preservation and augmentation of such
variations would depend on whether more evil was caused to the species
by the females being rendered conspicuous, than good to the males by
certain individuals being successful over their rivals.

As there can hardly be a doubt that both sexes of many butterflies and
moths have been rendered dull-coloured for the sake of protection, so
it may have been with the females alone of some species in which
successive variations towards dullness first appeared in the female sex
and were from the first limited in their transmission to the same sex.
If not thus limited, both sexes would become dull-coloured. We shall
immediately see, when we treat of mimickry, that the females alone of
certain butterflies have been rendered extremely beautiful for the sake
of protection, without any of the successive protective variations
having been transferred to the male, to whom they could not possibly
have been in the least degree injurious, and therefore could not have
been eliminated through natural selection. Whether in each particular
species, in which the sexes differ in colour, it is the female which has
been specially modified for the sake of protection; or whether it is the
male which has been specially modified for the sake of sexual
attraction, the female having retained her primordial colouring only
slightly changed through the agencies before alluded to; or whether
again both sexes have been modified, the female for protection and the
male for sexual attraction, can only be definitely decided when we know
the life-history of each species.

Without distinct evidence, I am unwilling to admit that a double process
of selection has long been going on with a multitude of species,—the
males having been rendered more brilliant by beating their rivals; and
the females more dull-coloured by having escaped from their enemies. We
may take as an instance the common brimstone butterfly (Gonepteryx),
which appears early in the spring before any other kind. The male of
this species is of a far more intense yellow than the female, though she
is almost equally conspicuous; and in this case it does not seem
probable that she specially acquired her pale tints as a protection,
though it is probable that the male acquired his bright colours as a
sexual attraction. The female of _Anthocharis cardamines_ does not
possess the beautiful orange tips to her wings with which the male is
ornamented; consequently she closely resembles the white butterflies
(Pieris) so common in our gardens; but we have no evidence that this
resemblance is beneficial. On the contrary, as she resembles both sexes
of several species of the same genus inhabiting various quarters of the
world, it is more probable that she has simply retained to a large
extent her primordial colours.

Various facts support the conclusion that with the greater number of
brilliantly-coloured Lepidoptera, it is the male which has been
modified; the two sexes having come to differ from each other, or to
resemble each other, according to which form of inheritance has
prevailed. Inheritance is governed by so many unknown laws or
conditions, that they seem to us to be most capricious in their
action;[524] and we can so far understand how it is that with
closely-allied species the sexes of some differ to an astonishing
degree, whilst the sexes of others are identical in colour. As the
successive steps in the process of variation are necessarily all
transmitted through the female, a greater or less number of such steps
might readily become developed in her; and thus we can understand the
frequent gradations from an extreme difference to no difference at all
between the sexes of the species within the same group. These cases of
gradation are much too common to favour the supposition that we here see
females actually undergoing the process of transition and losing their
brightness for the sake of protection; for we have every reason to
conclude that at any one time the greater number of species are in a
fixed condition. With respect to the differences between the females of
the species in the same genus or family, we can perceive that they
depend, at least in part, on the females partaking of the colours of
their respective males. This is well illustrated in those groups in
which the males are ornamented to an extraordinary degree; for the
females in these groups generally partake to a certain extent of the
splendour of their male partners. Lastly, we continually find, as
already remarked, that the females of almost all the species in the same
genus, or even family, resemble each other much more closely in colour
than do the males; and this indicates that the males have undergone a
greater amount of modification than the females.

_Mimickry._—This principle was first made clear in an admirable paper
by Mr. Bates,[525] who thus threw a flood of light on many obscure
problems. It had previously been observed that certain butterflies in S.
America belonging to quite distinct families, resembled the Heliconidæ
so closely in every stripe and shade of colour that they could not be
distinguished except by an experienced entomologist. As the Heliconidæ
are coloured in their usual manner, whilst the others depart from the
usual colouring of the groups to which they belong, it is clear that the
latter are the imitators, and the Heliconidæ the imitated. Mr. Bates
further observed that the imitating species are comparatively rare,
whilst the imitated swarm in large numbers; the two sets living mingled
together. From the fact of the Heliconidæ being conspicuous and
beautiful insects, yet so numerous in individuals and species, he
concluded that they must be protected from the attacks of birds by some
secretion or odour; and this hypothesis has now been confirmed by a
considerable body of curious evidence.[526] From these considerations
Mr. Bates inferred that the butterflies which imitate the protected
species had acquired their present marvellously deceptive appearance,
through variation and natural selection, in order to be mistaken for the
protected kinds and thus to escape being devoured. No explanation is
here attempted of the brilliant colours of the imitated, but only of the
imitating butterflies. We must account for the colours of the former in
the same general manner, as in the cases previously discussed in this
chapter. Since the publication of Mr. Bates’ paper, similar and equally
striking facts have been observed by Mr. Wallace[527] in the Malayan
region, and by Mr. Trimen in South Africa.

As some writers[528] have felt much difficulty in understanding how the
first steps in the process of mimickry could have been effected through
natural selection, it may be well to remark that the process probably
has never commenced with forms widely dissimilar in colour. But with two
species moderately like each other, the closest resemblance if
beneficial to either form could readily be thus gained; and if the
imitated form was subsequently and gradually modified through sexual
selection or any other means, the imitating form would be led along the
same track, and thus be modified to almost any extent, so that it might
ultimately assume an appearance or colouring wholly unlike that of the
other members of the group to which it belonged. As extremely slight
variations in colour would not in many cases suffice to render a species
so like another protected species as to lead to its preservation, it
should be remembered that many species of Lepidoptera are liable to
considerable and abrupt variations in colour. A few instances have been
given in this chapter; but under this point of view Mr. Bates’ original
paper on mimickry, as well as Mr. Wallace’s papers, should be consulted.

In the foregoing cases both sexes of the imitating species
resemble the imitated; but occasionally the female alone mocks a
brilliantly-coloured and protected species inhabiting the same district.
Consequently the female differs in colour from her own male, and, which
is a rare and anomalous circumstance, is the more brightly-coloured of
the two. In all the few species of Pieridæ, in which the female is more
conspicuously coloured than the male, she imitates, as I am informed by
Mr. Wallace, some protected species inhabiting the same region. The
female of _Diadema anomala_ is rich purple-brown with almost the whole
surface glossed with satiny blue, and she closely imitates the
_Euplœa midamus_, “one of the commonest butterflies of the East;”
whilst the male is bronzy or olive-brown, with only a slight blue gloss
on the outer parts of the wings.[529] Both sexes of this Diadema and of
_D. bolina_ follow the same habits of life, so that the differences in
colour between the sexes cannot be accounted for by exposure to
different conditions;[530] even if this explanation were admissible in
other instances.[531]

The above cases of female butterflies which are more brightly-coloured
than the males, shew us, firstly, that variations have arisen in a state
of nature in the female sex, and have been transmitted exclusively, or
almost exclusively, to the same sex; and, secondly, that this form of
inheritance has not been determined through natural selection. For if we
assume that the females, before they became brightly coloured in
imitation of some protected kind, were exposed during each season for a
longer period to danger than the males; or if we assume that they could
not escape so swiftly from their enemies, we can understand how they
alone might originally have acquired through natural selection and
sexually-limited inheritance their present protective colours. But
except on the principle of these variations having been transmitted
exclusively to the female offspring, we cannot understand why the males
should have remained dull-coloured; for it would surely not have been in
any way injurious to each individual male to have partaken by
inheritance of the protective colours of the female, and thus to have
had a better chance of escaping destruction. In a group in which
brilliant colours are so common as with butterflies, it cannot be
supposed that the males have been kept dull-coloured through sexual
selection by the females rejecting the individuals which were rendered
as beautiful as themselves. We may, therefore, conclude that in these
cases inheritance by one sex is not due to the modification through
natural selection of a tendency to equal inheritance by both sexes.

It may be well here to give an analogous case in another Order, of
characters acquired only by the female, though not in the least
injurious, as far as we can judge, to the male. Amongst the Phasmidæ, or
spectre-insects, Mr. Wallace states that “it is often the females alone
that so strikingly resemble leaves, while the males show only a rude
approximation.” Now, whatever may be the habits of these insects, it is
highly improbable that it could be disadvantageous to the males to
escape detection by resembling leaves.[532] Hence we may conclude that
the females alone in this latter as in the previous cases originally
varied in certain characters; these characters having been preserved and
augmented through ordinary selection for the sake of protection and from
the first transmitted to the female offspring alone.

_Bright Colours of Caterpillars._—Whilst reflecting on the beauty of
many butterflies, it occurred to me that some caterpillars were
splendidly coloured, and as sexual selection could not possibly have
here acted, it appeared rash to attribute the beauty of the mature
insect to this agency, unless the bright colours of their larvæ could
be in some manner explained. In the first place it may be observed that
the colours of caterpillars do not stand in any close correlation with
those of the mature insect. Secondly, their bright colours do not serve
in any ordinary manner as a protection. As an instance of this, Mr.
Bates informs me that the most conspicuous caterpillar which he ever
beheld (that of a Sphinx) lived on the large green leaves of a tree on
the open llanos of South America; it was about four inches in length,
transversely banded with black and yellow, and with its head, legs, and
tail of a bright red. Hence it caught the eye of any man who passed by
at the distance of many yards, and no doubt of every passing bird.

I then applied to Mr. Wallace, who has an innate genius for solving
difficulties. After some consideration he replied: “Most caterpillars
require protection, as may be inferred from some kinds being furnished
with spines or irritating hairs, and from many being coloured green like
the leaves on which they feed, or curiously like the twigs of the trees
on which they live.” I may add as another instance of protection, that
there is a caterpillar of a moth, as I am informed by Mr. J. Mansel
Weale, which lives on the mimosas in South Africa, and fabricates for
itself a case, quite undistinguishable from the surrounding thorns. From
such considerations Mr. Wallace thought it probable that
conspicuously-coloured caterpillars were protected by having a nauseous
taste; but as their skin is extremely tender, and as their intestines
readily protrude from a wound, a slight peck from the beak of a bird
would be as fatal to them as if they had been devoured. Hence, as Mr.
Wallace remarks, “distastefulness alone would be insufficient to protect
a caterpillar unless some outward sign indicated to its would-be
destroyer that its prey was a disgusting morsel.” Under these
circumstances it would be highly advantageous to a caterpillar to be
instantaneously and certainly recognised as unpalatable by all birds and
other animals. Thus the most gaudy colours would be serviceable, and
might have been gained by variation and the survival of the most
easily-recognised individuals.

This hypothesis appears at first sight very bold; but when it was
brought before the Entomological Society[533] it was supported by
various statements; and Mr. J. Jenner Weir, who keeps a large number of
birds in an aviary, has made, as he informs me, numerous trials, and
finds no exception to the rule, that all caterpillars of nocturnal and
retiring habits with smooth skins, all of a green colour, and all which
imitate twigs, are greedily devoured by his birds. The hairy and spinose
kinds are invariably rejected, as were four conspicuously-coloured
species. When the birds rejected a caterpillar, they plainly shewed, by
shaking their heads and cleansing their beaks, that they were disgusted
by the taste.[534] Three conspicuous kinds of caterpillars and moths
were also given by Mr. A. Butler to some lizards and frogs, and were
rejected; though other kinds were eagerly eaten. Thus the probable truth
of Mr. Wallace’s view is confirmed, namely, that certain caterpillars
have been made conspicuous for their own good, so as to be easily
recognised by their enemies, on nearly the same principle that certain
poisons are coloured by druggists for the good of man. This view will,
it is probable, be hereafter extended to many animals, which are
coloured in a conspicuous manner.

_Summary and Concluding Remarks on Insects._—Looking back to the
several Orders, we have seen that the sexes often differ in various
characters, the meaning of which is not understood. The sexes, also,
often differ in their organs of sense or locomotion, so that the males
may quickly discover or reach the females, and still oftener in the
males possessing diversified contrivances for retaining the females when
found. But we are not here much concerned with sexual differences of
these kinds.

In almost all the Orders, the males of some species, even of weak and
delicate kinds, are known to be highly pugnacious; and some few are
furnished with special weapons for fighting with their rivals. But the
law of battle does not prevail nearly so widely with insects as with the
higher animals. Hence probably it is that the males have not often been
rendered larger and stronger than the females. On the contrary they are
usually smaller, in order that they may be developed within a shorter
time, so as to be ready in large numbers for the emergence of the

In two families of the Homoptera the males alone possess, in an
efficient state, organs which may be called vocal; and in three families
of the Orthoptera the males alone possess stridulating organs. In both
cases these organs are incessantly used during the breeding-season, not
only for calling the females, but for charming or exciting them in
rivalry with other males. No one who admits the agency of natural
selection, will dispute that these musical instruments have been
acquired through sexual selection. In four other Orders the members of
one sex, or more commonly of both sexes, are provided with organs for
producing various sounds, which apparently serve merely as call-notes.
Even when both sexes are thus provided, the individuals which were able
to make the loudest or most continuous noise would gain partners before
those which were less noisy, so that their organs have probably been
gained through sexual selection. It is instructive to reflect on the
wonderful diversity of the means for producing sound, possessed by the
males alone or by both sexes in no less than six Orders, and which were
possessed by at least one insect at an extremely remote geological
epoch. We thus learn how effectual sexual selection has been in leading
to modifications of structure, which sometimes, as with the Homoptera,
are of an important nature.

From the reasons assigned in the last chapter, it is probable that the
great horns of the males of many lamellicorn, and some other beetles,
have been acquired as ornaments. So perhaps it may be with certain other
peculiarities confined to the male sex. From the small size of insects,
we are apt to undervalue their appearance. If we could imagine a male
Chalcosoma (fig. 15) with its polished, bronzed coat of mail, and vast
complex horns, magnified to the size of a horse or even of a dog, it
would be one of the most imposing animals in the world.

The colouring of insects is a complex and obscure subject. When the male
differs slightly from the female, and neither are brilliantly coloured,
it is probable that the two sexes have varied in a slightly different
manner, with the variations transmitted to the same sex, without any
benefit having been thus derived or evil suffered. When the male is
brilliantly coloured and differs conspicuously from the female, as with
some dragon-flies and many butterflies, it is probable that he alone has
been modified, and that he owes his colours to sexual selection; whilst
the female has retained a primordial or very ancient type of colouring,
slightly modified by the agencies before explained, and has therefore
not been rendered obscure, at least in most cases, for the sake of
protection. But the female alone has sometimes been coloured
brilliantly so as to imitate other protected species inhabiting the same
district. When the sexes resemble each other and both are obscurely
coloured, there is no doubt that they have been in a multitude of cases
coloured for the sake of protection. So it is in some instances when
both are brightly coloured, causing them to resemble surrounding objects
such as flowers, or other protected species, or indirectly by giving
notice to their enemies that they are of an unpalatable nature. In many
other cases in which the sexes resemble each other and are brilliantly
coloured, especially when the colours are arranged for display, we may
conclude that they have been gained by the male sex as an attraction,
and have been transferred to both sexes. We are more especially led to
this conclusion whenever the same type of coloration prevails throughout
a group, and we find that the males of some species differ widely in
colour from the females, whilst both sexes of other species are quite
alike, with intermediate gradations connecting these extreme states.

In the same manner as bright colours have often been partially
transferred from the males to the females, so it has been with the
extraordinary horns of many lamellicorn and some other beetles. So,
again, the vocal or instrumental organs proper to the males of the
Homoptera and Orthoptera have generally been transferred in a
rudimentary, or even in a nearly perfect condition to the females; yet
not sufficiently perfect to be used for producing sound. It is also an
interesting fact, as bearing on sexual selection, that the stridulating
organs of certain male Orthoptera are not fully developed until the last
moult; and that the colours of certain male dragon-flies are not fully
developed until some little time after their emergence from the pupal
state, and when they are ready to breed.

Sexual selection implies that the more attractive individuals are
preferred by the opposite sex; and as with insects, when the sexes
differ, it is the male which, with rare exceptions, is the most
ornamented and departs most from the type to which the species
belongs;—and as it is the male which searches eagerly for the female,
we must suppose that the females habitually or occasionally prefer the
more beautiful males, and that these have thus acquired their beauty.
That in most or all the orders the females have the power of rejecting
any particular male, we may safely infer from the many singular
contrivances possessed by the males, such as great jaws, adhesive
cushions, spines, elongated legs, &c., for seizing the female; for these
contrivances shew that there is some difficulty in the act. In the case
of unions between distinct species, of which many instances have been
recorded, the female must have been a consenting party. Judging from
what we know of the perceptive powers and affections of various insects,
there is no antecedent improbability in sexual selection having come
largely into action; but we have as yet no direct evidence on this head,
and some facts are opposed to the belief. Nevertheless, when we see many
males pursuing the same female, we can hardly believe that the pairing
is left to blind chance—that the female exerts no choice, and is not
influenced by the gorgeous colours or other ornaments, with which the
male alone is decorated.

If we admit that the females of the Homoptera and Orthoptera appreciate
the musical tones emitted by their male partners, and that the various
instruments for this purpose have been perfected through sexual
selection, there is little improbability in the females of other insects
appreciating beauty in form or colour, and consequently in such
characters having been thus gained by the males. But from the
circumstance of colour being so variable, and from its having been so
often modified for the sake of protection, it is extremely difficult to
decide in how large a proportion of cases sexual selection has come into
play. This is more especially difficult in those Orders, such as the
Orthoptera, Hymenoptera, and Coleoptera, in which the two sexes rarely
differ much in colour; for we are thus cut off from our best evidence of
some relation between the reproduction of the species and colour. With
the Coleoptera, however, as before remarked, it is in the great
lamellicorn group, placed by some authors at the head of the Order, and
in which we sometimes see a mutual attachment between the sexes, that we
find the males of some species possessing weapons for sexual strife,
others furnished with wonderful horns, many with stridulating organs,
and others ornamented with splendid metallic tints. Hence it seems
probable that all these characters have been gained through the same
means, namely sexual selection.

When we treat of Birds, we shall see that they present in their
secondary sexual characters the closest analogy with insects. Thus, many
male birds are highly pugnacious, and some are furnished with special
weapons for fighting with their rivals. They possess organs which are
used during the breeding-season for producing vocal and instrumental
music. They are frequently ornamented with combs, horns, wattles and
plumes of the most diversified kinds, and are decorated with beautiful
colours, all evidently for the sake of display. We shall find that, as
with insects, both sexes, in certain groups, are equally beautiful, and
are equally provided with ornaments which are usually confined to the
male sex. In other groups both sexes are equally plain-coloured and
unornamented. Lastly, in some few anomalous cases, the females are more
beautiful than the males. We shall often find, in the same group of
birds, every gradation from no difference between the sexes, to an
extreme difference. In the latter case we shall see that the females,
like female insects, often possess more or less plain traces of the
characters which properly belong to the males. The analogy, indeed, in
all these respects between birds and insects, is curiously close.
Whatever explanation applies to the one class probably applies to the
other; and this explanation, as we shall hereafter attempt to shew, is
almost certainly sexual selection.


  [1] As the works of the first-named authors are so well known,
  I need not give the titles; but as those of the latter are less
  well known in England, I will give them:—‘Sechs Vorlesungen
  über die Darwin’sche Theorie:’ zweite Auflage, 1868, von Dr. L.
  Büchner; translated into French under the title ‘Conférences
  sur la Théorie Darwinienne,’ 1869. ‘Der Mensch, im Lichte der
  Darwin’sche Lehre,’ 1865, von Dr. F. Rolle. I will not attempt
  to give references to all the authors who have taken the same
  side of the question. Thus G. Canestrini has published
  (‘Annuario della Soc. d. Nat.,’ Modena, 1867, p. 81) a very
  curious paper on rudimentary characters, as bearing on the
  origin of man. Another work has (1869) been published by Dr.
  Barrago Francesco, bearing in Italian the title of “Man, made
  in the image of God, was also made in the image of the ape.”

  [2] Prof. Häckel is the sole author who, since the publication
  of the ‘Origin,’ has discussed, in his various works, in a very
  able manner, the subject of sexual selection, and has seen its
  full importance.

  [3] ‘Grosshirnwindungen des Menschen,’ 1868, s. 96.

  [4] ‘Leç. sur la Phys.’ 1866, p. 890, as quoted by M. Dally,
  ‘L’Ordre des Primates et le Transformisme,’ 1868, p. 29.

  [5] ‘Naturgeschichte der Säugethiere von Paraguay,’ 1830, s.

  [6] Brehm, ‘Thierleben,’ B. i. 1864, s. 75, 86. On the Ateles,
  s. 105. For other analogous statements, see s. 25, 107.

  [7] With respect to insects see Dr. Laycock ‘On a General Law
  of Vital Periodicity,’ British Association, 1842. Dr.
  Macculloch, ‘Silliman’s North American Journal of Science,’
  vol. xvii. p. 305, has seen a dog suffering from tertian ague.

  [8] I have given the evidence on this head in my ‘Variation of
  Animals and Plants under Domestication,’ vol. ii. p. 15.

  [9] “Mares e diversis generibus Quadrumanorum sine dubio
  dignoscunt feminas humanas a maribus. Primum, credo, odoratu,
  postea aspectu. Mr. Youatt, qui diu in Hortis Zoologicis
  (Bestiariis) medicus animalium erat, vir in rebus observandis
  cautus et sagax, hoc mihi certissime probavit, et curatores
  ejusdem loci et alii e ministris confirmaverunt. Sir Andrew
  Smith et Brehm notabant idem in Cynocephalo. Illustrissimus
  Cuvier etiam narrat multa de hac re quâ ut opinor nihil turpius
  potest indicari inter omnia hominibus et Quadrumanis communia.
  Narrat enim Cynocephalum quendam in furorem incidere aspectu
  feminarum aliquarum, sed nequaquam accendi tanto furore ab
  omnibus. Semper eligebat juniores, et dignoscebat in turba, et
  advocabat voce gestuque.”

  [10] This remark is made with respect to Cynocephalus and the
  anthropomorphous apes by Geoffroy Saint-Hilaire and F. Cuvier,
  ‘Hist. Nat. des Mammifères,’ tom. i. 1824.

  [11] Huxley, ‘Man’s Place in Nature,’ 1863, p. 34.

  [12] ‘Man’s Place in Nature,’ 1863, p. 67.

  [13] The human embryo (upper fig.) is from Ecker, ‘Icones
  Phys.,’ 1851-1859, tab. xxx. fig. 2. This embryo was ten lines
  in length, so that the drawing is much magnified. The embryo of
  the dog is from Bischoff, ‘Entwicklungsgeschichte des
  Hunde-Eies,’ 1845, tab. xi. fig. 42 B. This drawing is five
  times magnified, the embryo being 25 days old. The internal
  viscera have been omitted, and the uterine appendages in both
  drawings removed. I was directed to these figures by Prof.
  Huxley, from whose work, ‘Man’s Place in Nature.’ the idea of
  giving them was taken. Häckel has also given analogous drawings
  in his ‘Schöpfungsgeschichte.’

  [14] Prof. Wyman in ‘Proc. of American Acad. of Sciences,’ vol.
  iv. 1860, p. 17.

  [15] Owen, ‘Anatomy of Vertebrates,’ vol. i. p. 533.

  [16] ‘Die Grosshirnwindungen des Menschen,’ 1868, s. 95.

  [17] ‘Anatomy of Vertebrates,’ vol. ii. p. 553.

  [18] ‘Proc. Soc. Nat. Hist.’ Boston, 1863, vol. ix. p. 185.

  [19] ‘Man’s Place in Nature,’ p. 65.

  [20] I had written a rough copy of this chapter before reading
  a valuable paper, “Caratteri rudimentali in ordine all’origine
  del uomo” (‘Annuario della Soc. d. Nat.,’ Modena, 1867, p. 81),
  by G. Canestrini, to which paper I am considerably indebted.
  Häckel has given admirable discussions on this whole subject,
  under the title of Dysteleology, in his ‘Generelle Morphologie’
  and ‘Schöpfungsgeschichte.’

  [21] Some good criticisms on this subject have been given by
  Messrs. Murie and Mivart, in ‘Transact. Zoolog. Soc.’ 1869,
  vol. vii. p. 92.

  [22] ‘Variation of Animals and Plants under Domestication,’
  vol. ii. pp. 317 and 397. See also ‘Origin of Species,’ 5th
  edit. p. 535.

  [23] For instance M. Richard (‘Annales des Sciences Nat.’ 3rd
  series, Zoolog. 1852, tom. xviii. p. 13) describes and figures
  rudiments of what he calls the “muscle pédieux de la main,”
  which he says is sometimes “infiniment petit.” Another muscle,
  called “le tibial postérieur,” is generally quite absent in the
  hand, but appears from time to time in a more or less
  rudimentary condition.

  [24] Prof. W. Turner, ‘Proc. Royal Soc. Edinburgh,’ 1866-67, p.

  [25] Canestrini quotes Hyrt. (‘Annuario della Soc. dei
  Naturalisti,’ Modena, 1867, p. 97) to the same effect.

  [26] ‘The Diseases of the Ear,’ by J. Toynbee, F.R.S., 1860, p.

  [27] See also some remarks, and the drawings of the ears of the
  Lemuroidea, in Messrs. Murie and Mivart’s excellent paper in
  ‘Transact. Zoolog. Soc.’ vol. vii. 1869, pp. 6 and 90.

  [28] Müller’s ‘Elements of Physiology,’ Eng. translat., 1842,
  vol. ii. p. 1117. Owen, ‘Anatomy of Vertebrates,’ vol. iii. p.
  260; ibid. on the Walrus, ‘Proc. Zoolog. Soc.’ November 8th,
  1854. See also R. Knox, ‘Great Artists and Anatomists,’ p. 106.
  This rudiment apparently is somewhat larger in Negroes and
  Australians than in Europeans, see Carl Vogt, ‘Lectures on
  Man,’ Eng. translat. p. 129.

  [29] ‘The Physiology and Pathology of Mind,’ 2nd edit. 1868, p.

  [30] Eschricht, Ueber die Richtung der Haare am menschlichen
  Körper ‘Müllers Archiv für Anat. und Phys.’ 1837, s. 47. I
  shall often have to refer to this very curious paper.

  [31] Paget, ‘Lectures on Surgical Pathology,’ 1853, vol. i. p.

  [32] Eschricht, ibid. s. 40, 47.

  [33] Dr. Webb, ‘Teeth in Man and the Anthropoid Apes,’ as
  quoted by Dr. C. Carter Blake in ‘Anthropological Review,’
  July, 1867, p. 299.

  [34] Owen, ‘Anatomy of Vertebrates,’ vol. iii. pp. 320, 321,
  and 325.

  [35] ‘On the Primitive Form of the Skull,’ Eng. translat. in
  ‘Anthropological Review,’ Oct. 1868, p. 426.

  [36] Owen, ‘Anatomy of Vertebrates,’ vol. iii. pp. 416, 434,

  [37] ‘Annuario della Soc. d. Nat.’ Modena, 1867, p. 94.

  [38] M. C. Martins (“De l’Unité Organique,” in ‘Revue des Deux
  Mondes,’ June 15, 1862, p. 16), and Häckel (‘Generelle
  Morphologie,’ B. ii. s. 278), have both remarked on the
  singular fact of this rudiment sometimes causing death.

  [39] ‘The Lancet,’ Jan. 24, 1863, p. 83. Dr. Knox, ‘Great
  Artists and Anatomists,’ p. 63. See also an important memoir on
  this process by Dr. Grube, in the ‘Bulletin de l’Acad. Imp. de
  St. Pétersbourg,’ tom. xii. 1867, p. 448.

  [40] “On the Caves of Gibraltar,” ‘Transact. Internat. Congress
  of Prehist. Arch.’ Third Session, 1869, p. 54.

  [41] Quatrefages has lately collected the evidence on this
  subject. ‘Revue des Cours Scientifiques,’ 1867-1868, p. 625.

  [42] Owen, ‘On the Nature of Limbs,’ 1849, p. 114.

  [43] Leuckart, in Todd’s ‘Cyclop. of Anat.’ 1849-52, vol. iv.
  p. 1415. In man this organ is only from three to six lines in
  length, but, like so many other rudimentary parts, it is
  variable in development as well as in other characters.

  [44] See, on this subject, Owen, ‘Anatomy of Vertebrates,’ vol.
  iii. pp. 675, 676, 706.

  [45] See the evidence on these points, as given by Lubbock,
  ‘Prehistoric Times,’ p. 354, &c.

  [46] ‘L’Instinct chez les Insectes.’ ‘Revue des Deux Mondes,’
  Feb. 1870, p. 690.

  [47] ‘The American Beaver and his Works,’ 1868.

  [48] ‘The Principles of Psychology,’ 2nd edit. 1870, pp.

  [49] ‘Contributions to the Theory of Natural Selection,’ 1870,
  p. 212

  [50] ‘Recherches sur les Mœurs des Fourmis,’ 1810, p. 173.

  [51] All the following statements, given on the authority of
  these two naturalists, are taken from Rengger’s ‘Naturges. der
  Säugethiere von Paraguay,’ 1830, s. 41-57, and from Brehm’s
  ‘Thierleben,’ B. i. s. 10-87.

  [52] ‘Bridgewater Treatise,’ p. 263.

  [53] W. C. L. Martin, ‘Nat. Hist. of Mammalia,’ 1841, p. 405.

  [54] Quoted by Vogt, ‘Mémoire sur les Microcéphales,’ 1867, p.

  [55] ‘The Variation of Animals and Plants under Domestication,’
  vol. i. p. 27.

  [56] ‘Les Mœurs des Fourmis,’ 1810, p. 150.

  [57] Quoted in Dr. Maudsley’s ‘Physiology and Pathology of
  Mind,’ 1868, pp. 19, 220.

  [58] Dr. Jerdon, ‘Birds of India,’ vol. i. 1862, p. xxi.

  [59] Mr. L. H. Morgan’s work on ‘The American Beaver,’ 1868,
  offers a good illustration of this remark. I cannot, however,
  avoid thinking that he goes too far in underrating the power of

  [60] ‘The Moor and the Loch,’ p. 45. Col. Hutchinson on ‘Dog
  Breaking,’ 1850, p. 46.

  [61] ‘Personal Narrative,’ Eng. translat., vol. iii. p. 106.

  [62] Quoted by Sir C. Lyell, ‘Antiquity of Man,’ p. 497.

  [63] ‘Journal of Researches during the Voyage of the “Beagle,”’
  1845, p. 398. ‘Origin of Species,’ 5th edit. p. 260.

  [64] ‘Lettres Phil. sur l’Intelligence des Animaux,’ nouvelle
  edit. 1802, p. 86.

  [65] See the evidence on this head in chap. i. vol. i. ‘On the
  Variation of Animals and Plants under Domestication.’

  [66] ‘Proc. Zoolog. Soc.’ 1864, p. 186.

  [67] Savage and Wyman in ‘Boston Journal of Nat. Hist.’ vol.
  iv. 1843-44, p. 383.

  [68] ‘Säugethiere von Paraguay,’ 1830, s. 51-56.

  [69] ‘Thierleben,’ B. i. s. 79, 82.

  [70] ‘The Malay Archipelago,’ vol. i. 1869, p. 87.

  [71] ‘Primeval Man,’ 1869, pp. 145, 147.

  [72] ‘Prehistoric Times,’ 1865, p. 473, &c.

  [73] Quoted in ‘Anthropological Review,’ 1864, p. 158.

  [74] Rengger, ibid. s. 45.

  [75] See my ‘Variation of Animals and Plants under
  Domestication,’ vol. i. p. 27.

  [76] See a discussion on this subject in Mr. E. B. Tylor’s very
  interesting work, ‘Researches into the Early History of
  Mankind,’ 1865, chaps. ii. to iv.

  [77] Hon. Daines Barrington in ‘Philosoph. Transactions,’ 1773,
  p. 262. See also Dureau de la Malle, in ‘Ann. des Sc. Nat.’ 3rd
  series, Zoolog. tom. x. p. 119.

  [78] ‘On the Origin of Language,’ by H. Wedgwood, 1866.
  ‘Chapters on Language,’ by the Rev. F. W. Farrar, 1865. These
  works are most interesting. See also ‘De la Phys. et de
  Parole,’ par Albert Lemoine, 1865, p. 190. The work on this
  subject, by the late Prof. Aug. Schleicher, has been translated
  by Dr. Bikkers into English, under the title of ‘Darwinism
  tested by the Science of Language,’ 1869.

  [79] Vogt, ‘Mémoire sur les Microcéphales,’ 1867, p. 169. With
  respect to savages, I have given some facts in my ‘Journal of
  Researches,’ &c., 1845, p. 206.

  [80] See clear evidence on this head in the two works so often
  quoted, by Brehm and Rengger.

  [81] See remarks on this head by Dr. Maudsley, ‘The Physiology
  and Pathology of Mind,’ 2nd edit. 1868, p. 199.

  [82] Many curious cases have been recorded. See, for instance,
  ‘Inquiries Concerning the Intellectual Powers,’ by Dr.
  Abercrombie, 1838, p. 150.

  [83] ‘The Variation of Animals and Plants under Domestication,’
  vol. ii. p. 6.

  [84] See some good remarks to this effect by Dr. Maudsley, ‘The
  Physiology and Pathology of Mind,’ 1808, p. 199.

  [85] Macgillivray, ‘Hist. of British Birds,’ vol. ii. 1839, p.
  29. An excellent observer, Mr. Blackwall, remarks that the
  magpie learns to pronounce single words, and even short
  sentences, more readily than almost any other British bird;
  yet, as he adds, after long and closely investigating its
  habits, he has never known it, in a state of nature, display
  any unusual capacity for imitation. ‘Researches in Zoology,’
  1834, p. 158.

  [86] See the very interesting parallelism between the
  development of species and languages, given by Sir C. Lyell in
  ‘The Geolog. Evidences of the Antiquity of Man,’ 1863, chap.

  [87] See remarks to this effect by the Rev. F. W. Farrar, in an
  interesting article, entitled “Philology and Darwinism” in
  ‘Nature,’ March 24th, 1870, p. 528.

  [88] ‘Nature,’ Jan. 6th, 1870, p. 257.

  [89] Quoted by C. S. Wake, ‘Chapters on Man,’ 1868, p. 101.

  [90] Buckland, ‘Bridgewater Treatise,’ p. 411.

  [91] See some good remarks on the simplification of languages,
  by Sir J. Lubbock, ‘Origin of Civilisation,’ 1870, p. 278.

  [92] ‘Conférences sur la Théorie Darwinienne,’ French
  translat., 1869, p. 132.

  [93] The Rev. Dr. J. M’Cann, ‘Anti-Darwinism,’ 1869, p. 13.

  [94] ‘The Spectator,’ Dec. 4th, 1869, p. 1430.

  [95] See an excellent article on this subject by the Rev. F. W.
  Farrar, in the ‘Anthropological Review,’ Aug. 1864, p. ccxvii.
  For further facts see Sir J. Lubbock, ‘Prehistoric Times,’ 2nd
  edit. 1869. p. 564; and especially the chapters on Religion in
  his ‘Origin of Civilisation,’ 1870.

  [96] The Worship of Animals and Plants, in the ‘Fortnightly
  Review,’ Oct. 1, 1869, p. 422.

  [97] Tylor, ‘Early History of Mankind,’ 1865, p. 6. See also
  the three striking chapters on the Development of Religion, in
  Lubbock’s ‘Origin of Civilisation,’ 1870. In a like manner Mr.
  Herbert Spencer, in his ingenious essay in the ‘Fortnightly
  Review’ (May 1st, 1870, p. 535), accounts for the earliest
  forms of religious belief throughout the world, by man being
  led through dreams, shadows, and other causes, to look at
  himself as a double essence, corporeal and spiritual. As the
  spiritual being is supposed to exist after death and to be
  powerful, it is propitiated by various gifts and ceremonies,
  and its aid invoked. He then further shews that names or
  nicknames given from some animal or other object to the early
  progenitors or founders of a tribe, are supposed after a long
  interval to represent the real progenitor of the tribe; and
  such animal or object is then naturally believed still to exist
  as a spirit, is held sacred, and worshipped as a god.
  Nevertheless I cannot but suspect that there is a still earlier
  and ruder stage, when anything which manifests power or
  movement is thought to be endowed with some form of life, and
  with mental faculties analogous to our own.

  [98] See an able article on the Psychical Elements of Religion,
  by Mr. L. Owen Pike, in ‘Anthropolog. Review,’ April, 1870, p.

  [99] ‘Religion, Moral, &c., der Darwin’schen Art-Lehre,’ 1869,
  s. 53.

  [100] ‘Prehistoric Times,’ 2nd edit. p. 571. In this work (at
  p. 553) there will be found an excellent account of the many
  strange and capricious customs of savages.

  [101] See, for instance, on this subject, Quatrefages, ‘Unité
  de l’Espèce Humaine,’ 1861, p. 21, &c.

  [102] ‘Dissertation on Ethical Philosophy,’ 1837, p. 231, &c.

  [103] ‘Metaphysics of Ethics,’ translated by J. W. Semple,
  Edinburgh, 1836, p. 136.

  [104] Mr. Bain gives a list (‘Mental and Moral Science,’ 1868,
  p. 543-725) of twenty-six British authors who have written on
  this subject, and whose names are familiar to every reader; to
  these, Mr. Bain’s own name, and those of Mr. Lecky, Mr.
  Shadworth Hodgson, and Sir J. Lubbock, as well as of others,
  may be added.

  [105] Sir B. Brodie, after observing that man is a social
  animal (‘Psychological Enquiries,’ 1854, p. 192), asks the
  pregnant question, “ought not this to settle the disputed
  question as to the existence of a moral sense?” Similar ideas
  have probably occurred to many persons, as they did long ago to
  Marcus Aurelius. Mr. J. S. Mill speaks, in his celebrated work,
  ‘Utilitarianism,’ (1864, p. 46), of the social feelings as a
  “powerful natural sentiment,” and as “the natural basis of
  sentiment for utilitarian morality;” but on the previous page
  he says, “if, as is my own belief, the moral feelings are not
  innate, but acquired, they are not for that reason less
  natural.” It is with hesitation that I venture to differ from
  so profound a thinker, but it can hardly be disputed that the
  social feelings are instinctive or innate in the lower animals;
  and why should they not be so in man? Mr. Bain (see, for
  instance, ‘The Emotions and the Will,’ 1865, p. 481) and others
  believe that the moral sense is acquired by each individual
  during his lifetime. On the general theory of evolution this is
  at least extremely improbable.

  [106] ‘Die Darwin’sche Theorie,’ s. 101.

  [107] Mr. R. Brown in ‘Proc. Zoolog. Soc.’ 1868, p. 409.

  [108] Brehm, ‘Thierleben,’ B. i. 1864, s. 52, 79. For the case
  of the monkeys extracting thorns from each other, see s. 54.
  With respect to the Hamadryas turning over stones, the fact is
  given (s. 76) on the evidence of Alvarez, whose observations
  Brehm thinks quite trustworthy. For the cases of the old male
  baboons attacking the dogs, see s. 79; and with respect to the
  eagle, s. 56.

  [109] ‘Annals and Mag. of Nat. Hist.’ November, 1868, p. 382.

  [110] Sir J. Lubbock, ‘Prehistoric Times,’ 2nd edit. p. 446.

  [111] As quoted by Mr. L. H. Morgan, ‘The American Beaver,’
  1868, p. 272. Capt. Stansbury also gives an interesting account
  of the manner in which a very young pelican, carried away by a
  strong stream, was guided and encouraged in its attempts to
  reach the shore by half a dozen old birds.

  [112] As Mr. Bain states, “effective aid to a sufferer springs
  from sympathy proper:” ‘Mental and Moral Science,’ 1868, p.

  [113] ‘Thierleben,’ B. i. s. 85.

  [114] ‘De l’Espèce et de la Class.’ 1869, p. 97.

  [115] ‘Der Darwin’schen Art-Lehre,’ 1869, s. 54.

  [116] Brehm, ‘Thierleben,’ B. i. s. 76.

  [117] See the first and striking chapter in Adam Smith’s
  ‘Theory of Moral Sentiments.’ Also Mr. Bain’s ‘Mental and Moral
  Science,’ 1868, p. 244, and 275-282. Mr. Bain states, that
  “sympathy is, indirectly, a source of pleasure to the
  sympathiser;” and he accounts for this through reciprocity. He
  remarks that “the person benefited, or others in his stead, may
  make up, by sympathy and good offices returned, for all the
  sacrifice.” But if, as appears to be the case, sympathy is
  strictly an instinct, its exercise would give direct pleasure,
  in the same manner as the exercise, as before remarked, of
  almost every other instinct.

  [118] This fact, the Rev. L. Jenyns states (see his edition of
  ‘White’s Nat. Hist. of Selborne,’ 1853, p. 204) was first
  recorded by the illustrious Jenner, in ‘Phil. Transact.’ 1824,
  and has since been confirmed by several observers, especially
  by Mr. Blackwall. This latter careful observer examined, late
  in the autumn, during two years, thirty-six nests; he found
  that twelve contained young dead birds, five contained eggs on
  the point of being hatched, and three eggs not nearly hatched.
  Many birds not yet old enough for a prolonged flight are
  likewise deserted and left behind. See Blackwall, ‘Researches
  in Zoology,’ 1834, pp. 108, 118. For some additional evidence,
  although this is not wanted, see Leroy, ‘Lettres Phil.’ 1802,
  p. 217.

  [119] Hume remarks (‘An Enquiry Concerning the Principles of
  Morals,’ edit. of 1751, p. 132), “there seems a necessity for
  confessing that the happiness and misery of others are not
  spectacles altogether indifferent to us, but that the view of
  the former ... communicates a secret joy; the appearance of the
  latter ... throws a melancholy damp over the imagination.”

  [120] ‘Mental and Moral Science,’ 1868, p. 254.

  [121] I have given one such case, namely of three Patagonian
  Indians who preferred being shot, one after the other, to
  betraying the plans of their companions in war (‘Journal of
  Researches,’ 1845, p. 103).

  [122] Dr. Prosper Despine, in his ‘Psychologie Naturelle,’ 1868
  (tom. i. p. 243; tom ii. p. 169) gives many curious cases of
  the worst criminals, who apparently have been entirely
  destitute of conscience.

  [123] See an able article in the ‘North British Review,’ 1867,
  p. 395. See also Mr. W. Bagehot’s articles on the Importance of
  Obedience and Coherence to Primitive Man, in the ‘Fortnightly
  Review,’ 1867, p. 529, and 1868, p. 457, &c.

  [124] The fullest account which I have met with is by Dr.
  Gerland, in his ‘Ueber das Aussterben der Naturvölker,’ 1868;
  but I shall have to recur to the subject of infanticide in a
  future chapter.

  [125] See the very interesting discussion on Suicide in Lecky’s
  ‘History of European Morals,’ vol. i. 1869, p. 223.

  [126] See, for instance, Mr. Hamilton’s account of the Kaffirs,
  ‘Anthropological Review,’ 1870, p. xv.

  [127] Mr. M’Lennan has given ‘Primitive Marriage,’ 1865, p.
  176, a good collection of facts on this head.

  [128] Lecky, ‘History of European Morals,’ vol. i. 1869, p.

  [129] ‘Embassy to China,’ vol. ii. p. 348.

  [130] See on this subject copious evidence in Chap. vii. of Sir
  J. Lubbock, ‘Origin of Civilisation,’ 1870.

  [131] For instance Lecky, ‘Hist. European Morals,’ vol. i. p.

  [132] This term is used in an able article in the ‘Westminster
  Review,’ Oct. 1869, p. 498. For the Greatest Happiness
  principle, see J. S. Mill, ‘Utilitarianism,’ p. 17.

  [133] Good instances are given by Mr. Wallace in ‘Scientific
  Opinion,’ Sept. 15, 1869; and more fully in his ‘Contributions
  to the Theory of Natural Selection,’ 1870, p. 353.

  [134] Tennyson, ‘Idylls of the King,’ p. 244.

  [135] ‘The Thoughts of the Emperor M. Aurelius Antoninus,’ Eng.
  translat., 2nd edit., 1869, p. 112. Marcus Aurelius was born
  A.D. 121.

  [136] Letter to Mr. Mill in Bain’s ‘Mental and Moral Science,’
  1868, p. 722.

  [137] A writer in the ‘North British Review’ (July, 1869, p.
  531), well capable of forming a sound judgment, expresses
  himself strongly to this effect. Mr. Lecky (‘Hist. of Morals,’
  vol. i. p. 143) seems to a certain extent to coincide.

  [138] See his remarkable work on ‘Hereditary Genius,’ 1869, p.
  349. The Duke of Argyll (‘Primeval Man,’ 1869, p. 188) has some
  good remarks on the contest in man’s nature between right and

  [139] ‘The Thoughts of Marcus Aurelius,’ &c., p. 139.

  [140] ‘Investigations in Military and Anthropolog. Statistics
  of American Soldiers,’ by B. A. Gould, 1869, p. 256.

  [141] With respect to the “Cranial forms of the American
  aborigines,” see Dr. Aitken Meigs in ‘Proc. Acad. Nat. Sci.’
  Philadelphia, May, 1866. On the Australians, see Huxley, in
  Lyell’s ‘Antiquity of Man,’ 1863, p. 87. On the Sandwich
  Islanders, Prof. J. Wyman, ‘Observations on Crania,’ Boston,
  1868, p. 18.

  [142] ‘Anatomy of the Arteries,’ by R. Quain.

  [143] ‘Transact. Royal Soc.’ Edinburgh, vol. xxiv. p. 175, 189.

  [144] ‘Proc. Royal Soc.’ 1867, p. 544; also 1868, p. 483, 524.
  There is a previous paper, 1866, p. 229.

  [145] ‘Proc. R. Irish Academy,’ vol. x. 1868, p. 141.

  [146] ‘Act. Acad.,’ St. Petersburg, 1778, part ii. p. 217.

  [147] Brehm, ‘Thierleben,’ B. i. s. 58, 87. Rengger,
  ‘Säugethiere von Paraguay,’ s. 57.

  [148] ‘Variation of Animals and Plants under Domestication,’
  vol. ii. chap. xii.

  [149] ‘Hereditary Genius: an Inquiry into its Laws and
  Consequences,’ 1869.

  [150] Mr. Bates remarks (‘The Naturalist on the Amazons,’ 1863,
  vol. ii. p. 159), with respect to the Indians of the same S.
  American tribe, “no two of them were at all similar in the
  shape of the head; one man had an oval visage with fine
  features, and another was quite Mongolian in breadth and
  prominence of cheek, spread of nostrils, and obliquity of

  [151] Blumenbach, ‘Treatises on Anthropolog.’ Eng. translat.,
  1865, p. 205.

  [152] Godron, ‘De l’Espèce,’ 1859, tom. ii. livre 3.
  Quatrefages, ‘Unité de l’Espèce Humaine,’ 1861. Also Lectures
  on Anthropology, given in the ‘Revue des Cours Scientifiques,’

  [153] ‘Hist. Gen. et Part. des Anomalies de l’Organisation,’ in
  three volumes, tom. i. 1832.

  [154] I have fully discussed these laws in my ‘Variation of
  Animals and Plants under Domestication,’ vol. ii. chap. xxii.
  and xxiii. M. J. P. Durand has lately 1868; published a
  valuable essay ‘De l’Influence des Milieux, &c.’ He lays much
  stress on the nature of the soil.

  [155] ‘Investigations in Military and Anthrop. Statistics,’ &c.
  1869, by B. A. Gould, p. 93, 107, 126, 131, 134.

  [156] For the Polynesians, see Prichard’s ‘Physical Hist. of
  Mankind,’ vol. v. 1847, p. 145, 283. Also Godron, ‘De
  l’Espèce,’ tom. ii. p. 289. There is also a remarkable
  difference in appearance between the closely-allied Hindoos
  inhabiting the Upper Ganges and Bengal; see Elphinstone’s
  ‘History of India,’ vol. i. p. 324.

  [157] ‘Memoirs, Anthropolog. Soc.’ vol. iii. 1867-69, p. 561,
  565, 567.

  [158] Dr. Brakenridge, ‘Theory of Diathesis,’ ‘Medical Times,’
  June 19 and July 17, 1869.

  [159] I have given authorities for these several statements in
  my ‘Variation of Animals under Domestication,’ vol. ii. p.
  297-300. Dr. Jaeger, “Ueber das Längenwachsthum der Knochen,”
  ‘Jenaischen Zeitschrift,’ B. v. Heft i.

  [160] ‘Investigations,’ &c. By B. A. Gould, 1869, p. 288.

  [161] ‘Säugethiere von Paraguay,’ 1830, s. 4.

  [162] ‘History of Greenland,’ Eng. translat. 1767, vol. i. p.

  [163] ‘Intermarriage.’ By Alex. Walker, 1838. p. 377.

  [164] ‘The Variation of Animals under Domestication,’ vol. i.
  p. 173.

  [165] ‘Principles of Biology,’ vol. i. p. 455.

  [166] Paget, ‘Lectures on Surgical Pathology,’ vol. i. 1853, p.

  [167] ‘The Variation of Animals under Domestication,’ vol. ii.
  p. 8.

  [168] ‘Säugethiere von Paraguay,’ s. 8, 10. I have had good
  opportunities for observing the extraordinary power of eyesight
  in the Fuegians.’ See also Lawrence (‘Lectures on Physiology,’
  &c., 1822, p. 404) on this same subject. M. Giraud-Teulon has
  recently collected (‘Revue des Cours Scientifiques,’ 1870, p.
  625) a large and valuable body of evidence proving that the
  cause of short-sight, “_C’est le travail assidu, de près._”

  [169] Prichard, ‘Phys. Hist. of Mankind,’ on the authority of
  Blumenbach, vol. i. 1851, p. 311; for the statement by Pallas,
  vol. iv. 1844, p. 407.

  [170] Quoted by Prichard, ‘Researches into the Phys. Hist. of
  Mankind,’ vol. v. p. 463.

  [171] Mr. Forbes’ valuable paper is now published in the
  ‘Journal of the Ethnological Soc. of London,’ new series, vol.
  ii. 1870, p. 193.

  [172] Dr. Wilckens (‘Landwirthschaft. Wochenblatt,’ No. 10,
  1869) has lately published an interesting essay shewing how
  domestic animals, which live in mountainous regions, have their
  frames modified.

  [173] ‘Mémoire sur les Microcéphales,’ 1867, p. 50, 125, 169,
  171, 184-198.

  [174] See Dr. A. Farre’s well-known article in the ‘Cyclop. of
  Anat. and Phys.’ vol. v. 1859, p. 642. Owen ‘Anatomy of
  Vertebrates,’ vol. iii. 1868, p. 687. Prof. Turner in
  ‘Edinburgh Medical Journal,’ Feb. 1865.

  [175] ‘Annuario della Soc. dei Naturalisti in Modena,’ 1867, p.
  83. Prof. Canestrini gives extracts on this subject from
  various authorities. Laurillard remarks, that as he has found a
  complete similarity in the form, proportions, and connexion of
  the two malar bones in several human subjects and in certain
  apes, he cannot consider this disposition of the parts as
  simply accidental.

  [176] A whole series of cases is given by Isid. Geoffroy
  St.-Hilaire, ‘Hist. des Anomalies,’ tom. iii. p. 437.

  [177] In my ‘Variation of Animals under Domestication’ (vol.
  ii. p. 57) I attributed the not very rare cases of
  supernumerary mammæ in women to reversion. I was led to this as
  a _probable_ conclusion, by the additional mammæ being
  generally placed symmetrically on the breast, and more
  especially from one case, in which a single efficient mamma
  occurred in the inguinal region of a woman, the daughter of
  another woman with supernumerary mammæ. But Prof. Preyer (‘Der
  Kampf um das Dasein,’ 1869, s. 45) states that _mammæ erraticæ_
  have been known to occur in other situations, even on the back;
  so that the force of my argument is greatly weakened or perhaps
  quite destroyed.

  With much hesitation I, in the same work (vol. ii. p. 12),
  attributed the frequent cases of polydactylism in men to
  reversion. I was partly led to this through Prof. Owen’s
  statement, that some of the Ichthyopterygia possess more than
  five digits, and therefore, as I supposed, had retained a
  primordial condition; but after reading Prof. Gegenbaur’s paper
  (‘Jenaischen Zeitschrift,’ B. v. Heft 3, s. 341), who is the
  highest authority in Europe on such a point, and who disputes
  Owen’s conclusion, I see that it is extremely doubtful whether
  supernumerary digits can thus be accounted for. It was the fact
  that such digits not only frequently occur and are strongly
  inherited, but have the power of regrowth after amputation,
  like the normal digits of the lower vertebrata, that chiefly
  led me to the above conclusion. This extraordinary fact of
  their regrowth remains inexplicable, if the belief in reversion
  to some extremely remote progenitor must be rejected. I cannot,
  however, follow Prof. Gegenbaur in supposing that additional
  digits could not reappear through reversion, without at the
  same time other parts of the skeleton being simultaneously and
  similarly modified; for single characters often reappear
  through reversion.

  [178] ‘Anatomy of Vertebrates,’ vol. iii. 1868, p. 323.

  [179] ‘Generelle Morphologie,’ 1866, B. ii. s. clv.

  [180] Carl Vogt’s ‘Lectures on Man,’ Eng. translat. 1864, p.

  [181] C. Carter Blake, on a jaw from La Naulette, ‘Anthropolog.
  Review,’ 1867, p. 295. Schaaffhausen, ibid. 1868, p. 426.

  [182] ‘The Anatomy of Expression,’ 1844, p. 110, 131.

  [183] Quoted by Prof. Canestrini in the ‘Annuario,’ &c., 1867,
  p. 90.

  [184] These papers deserve careful study by any one who desires
  to learn how frequently our muscles vary, and in varying come
  to resemble those of the Quadrumana. The following references
  relate to the few points touched on in my text: Proc. Royal
  Soc. vol. xiv. 1865, p. 379-384; vol. xv. 1866, p. 241, 242;
  vol. xv. 1867, p. 544; vol. xvi. 1868, p. 524. I may here add
  that Dr. Murie and Mr. St. George Mivart have shewn in their
  Memoir on the Lemuroidea (‘Transact. Zoolog. Soc.’ vol. vii.
  1869, p. 96), how extraordinarily variable some of the muscles
  are in these animals, the lowest members of the Primates.
  Gradations, also, in the muscles leading to structures found in
  animals still lower in the scale, are numerous in the

  [185] Prof. Macalister in ‘Proc. R. Irish Academy,’ vol. x.
  1868, p. 124.

  [186] Prof. Macalister (ibid. p. 121) has tabulated his
  observations, and finds that muscular abnormalities are most
  frequent in the fore-arms, secondly in the face, thirdly in the
  foot, &c.

  [187] The Rev. Dr. Haughton, after giving (‘Proc. R. Irish
  Academy,’ June 27, 1864, p. 715) a remarkable case of variation
  in the human _flexor pollicis longus_, adds, “This remarkable
  example shews that man may sometimes possess the arrangement of
  tendons of thumb and fingers characteristic of the macaque; but
  whether such a case should be regarded as a macaque passing
  upwards into a man, or a man passing downwards into a macaque,
  or as a congenital freak of nature, I cannot undertake to say.”
  It is satisfactory to hear so capable an anatomist, and so
  embittered an opponent of evolutionism, admitting even the
  possibility of either of his first propositions. Prof.
  Macalister has also described (‘Proc. R. Irish Acad.’ vol. x.
  1864, p. 138) variations in the _flexor pollicis longus_,
  remarkable from their relations to the same muscle in the

  [188] The authorities for these several statements are given in
  my ‘Variation of Animals under Domestication,’ vol. ii. p.

  [189] This whole subject has been discussed in chap. xxiii.
  vol. ii. of my ‘Variation of Animals and Plants under

  [190] See the ever memorable ‘Essay on the Principle of
  Population,’ by the Rev. T. Malthus, vol. i. 1826, p. 6, 517.

  [191] ‘Variation of Animals and Plants under Domestication,’
  vol. ii. p. 111-113, 163.

  [192] Mr. Sedgwick, ‘British and Foreign Medico-Chirurg.
  Review,’ July, 1863, p. 170.

  [193] ‘The Annals of Rural Bengal,’ by W. W. Hunter, 1868, p.

  [194] ‘Primitive Marriage,’ 1865.

  [195] See some good remarks to this effect by W. Stanley
  Jevons, “A Deduction from Darwin’s Theory,” ‘Nature,’ 1869, p.

  [196] Latham, ‘Man and his Migrations,’ 1851, p. 135.

  [197] Messrs. Murie and Mivart in their “Anatomy of the
  Lemuroidea” (‘Transact. Zoolog. Soc.’ vol. vii. 1869, p. 96-98)
  say, “some muscles are so irregular in their distribution that
  they cannot be well classed in any of the above groups.” These
  muscles differ even on the opposite sides of the same

  [198] ‘Quarterly Review,’ April, 1869, p. 392. This subject is
  more fully discussed in Mr. Wallace’s ‘Contributions to the
  Theory of Natural Selection,’ 1870, in which all the essays
  referred to in this work are republished. The ‘Essay on Man’
  has been ably criticised by Prof. Claparède, one of the most
  distinguished zoologists in Europe, in an article published in
  the ‘Bibliothèque Universelle,’ June, 1870. The remark quoted
  in my text will surprise every one who has read Mr. Wallace’s
  celebrated paper on ‘The Origin of Human Races deduced from the
  Theory of Natural Selection,’ originally published in the
  ‘Anthropological Review,’ May, 1864, p. clviii. I cannot here
  resist quoting a most just remark by Sir J. Lubbock
  (‘Prehistoric Times,’ 1865, p. 479) in reference to this paper,
  namely, that Mr. Wallace, “with characteristic unselfishness,
  ascribes it (_i.e._ the idea of natural selection) unreservedly
  to Mr. Darwin, although, as is well known, he struck out the
  idea independently, and published it, though not with the same
  elaboration, at the same time.”

  [199] Quoted by Mr. Lawson Tait in his “Law of Natural
  Selection,”—‘Dublin Quarterly Journal of Medical Science,’
  Feb. 1869. Dr. Keller is likewise quoted to the same effect.

  [200] Owen, ‘Anatomy of Vertebrates,’ vol. iii. p. 71.

  [201] ‘Quarterly Review,’ April, 1869, p. 392.

  [202] In _Hylobates syndactylus_, as the name expresses, two of
  the digits regularly cohere; and this, as Mr. Blyth informs me,
  is occasionally the case with the digits of _H. agilis_, _lar_,
  and _leuciscus_.

  [203] Brehm, ‘Thierleben,’ B. i. s. 80.

  [204] “The Hand, its mechanism,” &c. ‘Bridgewater Treatise,’
  1833, p. 38.

  [205] Häckel has an excellent discussion on the steps by which
  man became a biped: ‘Natürliche Schöpfungsgeschichte,’ 1868, s.
  507. Dr. Büchner (‘Conférences sur la Théorie Darwinienne,’
  1869, p. 135) has given good cases of the use of the foot as a
  prehensile organ by man; also on the manner of progression of
  the higher apes to which I allude in the following paragraph:
  see also Owen (‘Anatomy of Vertebrates,’ vol. iii. p. 71) on
  this latter subject.

  [206] “On the Primitive Form of the Skull,” translated in
  ‘Anthropological Review,’ Oct. 1868, p. 428. Owen (‘Anatomy of
  Vertebrates,’ vol. ii. 1866, p. 551) on the mastoid processes
  in the higher apes.

  [207] ‘Die Grenzen der Thierwelt, eine Betrachtung zu Darwin’s
  Lehre,’ 1868, s. 51.

  [208] Dujardin, ‘Annales des Sc. Nat.’ 3rd series, Zoolog. tom.
  xiv. 1850, p. 203. See also Mr. Lowne, ‘Anatomy and Phys. of
  the _Musca vomitoria_,’ 1870, p. 14. My son, Mr. F. Darwin,
  dissected for me the cerebral ganglia of the _Formica rufa_.

  [209] ‘Philosophical Transactions,’ 1869, p. 513.

  [210] Quoted in C. Vogt’s ‘Lectures on Man,’ Eng. translat.
  1864, p. 88, 90. Prichard, ‘Phys. Hist. of Mankind,’ vol. i.
  1838, p. 305.

  [211] ‘Comptes Rendus des Séances,’ &c. June 1, 1868.

  [212] ‘The Variation of Animals and Plants under
  Domestication,’ vol. ii. p. 124-129.

  [213] Schaaffhausen gives from Blumenbach and Busch, the cases
  of the spasms and cicatrix, in ‘Anthropolog. Review,’ Oct.
  1868, p. 420. Dr. Jarrold (‘Anthropologia,’ 1808, p. 115, 116)
  adduces from Camper and from his own observations, cases of the
  modification of the skull from the head being fixed in an
  unnatural position. He believes that certain trades, such as
  that of a shoemaker, by causing the head to be habitually held
  forward, makes the forehead more rounded and prominent.

  [214] ‘Variation of Animals,’ &c., vol. i. p. 117 on the
  elongation of the skull; p. 119, on the effect of the lopping
  of one ear.

  [215] Quoted by Schaaffhausen, in ‘Anthropolog. Review,’ Oct.
  1868, p. 419.

  [216] Owen, ‘Anatomy of Vertebrates,’ vol. iii. p. 619.

  [217] Isidore Geoffroy St.-Hilaire remarks (‘Hist. Nat.
  Générale,’ tom. ii. 1859, p. 215-217) on the head of man being
  covered with long hair; also on the upper surfaces of monkeys
  and of other mammals being more thickly clothed than the lower
  surfaces. This has likewise been observed by various authors.
  Prof. P. Gervais (‘Hist. Nat. des Mammifères,’ tom. i. 1854, p.
  28), however, states that in the Gorilla the hair is thinner on
  the back, where it is partly rubbed off, than on the lower

  [218] Mr. St. George Mivart, ‘Proc. Zoolog. Soc.’ 1865, p. 562,
  583. Dr. J. E. Gray, ‘Cat. Brit. Mus.: Skeletons.’ Owen,
  ‘Anatomy of Vertebrates,’ vol. ii. p. 517. Isidore Geoffroy,
  ‘Hist. Nat. Gén.’ tom. ii. p. 244.

  [219] ‘The Variation of Animals and Plants under
  Domestication,’ vol. ii. p. 280, 282.

  [220] ‘Primeval Man,’ 1869, p. 66.

  [221] ‘Anthropological Review,’ May, 1864, p. clviii.

  [222] After a time the members or tribes which are absorbed
  into another tribe assume, as Mr. Maine remarks (‘Ancient Law,’
  1861, p. 131), that they are the co-descendants of the same

  [223] Morlot, ‘Soc. Vaud. Sc. Nat.’ 1860, p. 294.

  [224] I have given instances in my ‘Variation of Animals under
  Domestication,’ vol. ii. p. 196.

  [225] See a remarkable series of articles on Physics and
  Politics in the ‘Fortnightly Review,’ Nov. 1867; April 1, 1868;
  July 1, 1869.

  [226] ‘Origin of Civilisation,’ 1870, p. 265.

  [227] Mr. Wallace gives cases in his ‘Contributions to the
  Theory of Natural Selection,’ 1870, p. 354.

  [228] ‘Ancient Law,’ 1861, p. 22. For Mr. Bagehot’s remarks,
  ‘Fortnightly Review,’ April 1, 1868, p. 452.

  [229] ‘The Variation of Animals and Plants under
  Domestication,’ vol. i. p. 309.

  [230] ‘Fraser’s Magazine,’ Sept. 1868, p. 353. This article
  seems to have struck many persons, and has given rise to two
  remarkable essays and a rejoinder in the ‘Spectator,’ Oct. 3rd
  and 17th 1868. It has also been discussed in the ‘Q. Journal of
  Science,’ 1869, p. 152, and by Mr. Lawson Tait in the ‘Dublin
  Q. Journal of Medical Science,’ Feb. 1869, and by Mr. E. Ray
  Lankester in his ‘Comparative Longevity,’ 1870, p. 128. Similar
  views appeared previously in the ‘Australasian,’ July 13, 1867.
  I have borrowed ideas from several of these writers.

  [231] For Mr. Wallace, see ‘Anthropolog. Review,’ as before
  cited. Mr. Galton in ‘Macmillan’s Magazine,’ Aug. 1865, p. 318;
  also his great work, ‘Hereditary Genius,’ 1870.

  [232] ‘Hereditary Genius,’ 1870, p. 132-140.

  [233] See the fifth and sixth columns, compiled from good
  authorities, in the table given in Mr. E. R. Lankester’s
  ‘Comparative Longevity,’ 1870, p. 115.

  [234] ‘Hereditary Genius,’ 1870, p. 330.

  [235] ‘Origin of Species’ (fifth edition, 1869), p. 104.

  [236] ‘Hereditary Genius,’ 1870, p. 347.

  [237] E. Ray Lankester, ‘Comparative Longevity,’ 1870, p. 115.
  The table of the intemperate is from Nelson’s ‘Vital
  Statistics.’ In regard to profligacy, see Dr. Farr, “Influence
  of Marriage on Mortality,” ‘Nat. Assoc. for the Promotion of
  Social Science,’ 1858.

  [238] ‘Fraser’s Magazine,’ Sept. 1868, p. 353. ‘Macmillan’s
  Magazine,’ Aug. 1865, p. 318. The Rev. F. W. Farrar (‘Fraser’s
  Mag.,’ Aug. 1870, p. 264) takes a different view.

  [239] “On the Laws of the Fertility of Women,” in ‘Transact.
  Royal Soc.’ Edinburgh, vol. xxiv. p. 287. See, also, Mr.
  Galton, ‘Hereditary Genius,’ p. 352-357, for observations to
  the above effect.

  [240] ‘Tenth Annual Report of Births, Deaths, &c., in
  Scotland,’ 1867, p. xxix.

  [241] These quotations are taken from our highest authority on
  such questions, namely, Dr. Farr, in his paper “On the
  Influence of Marriage on the Mortality of the French People,”
  read before the Nat. Assoc. for the Promotion of Social
  Science, 1858.

  [242] Dr. Farr, ibid. The quotations given below are extracted
  from the same striking paper.

  [243] I have taken the mean of the quinquennial means, given in
  ‘The Tenth Annual Report of Births, Deaths, &c., in Scotland,’
  1867. The quotation from Dr. Stark is copied from an article in
  the ‘Daily News,’ Oct. 17th, 1868, which Dr. Farr considers
  very carefully written.

  [244] See the ingenious and original argument on this subject
  by Mr. Galton, ‘Hereditary Genius,’ p. 340-342.

  [245] Mr. Greg, ‘Fraser’s Magazine,’ Sept. 1868, p. 357.

  [246] ‘Hereditary Genius,’ 1870, p. 357-359. The Rev. F. H.
  Farrar (‘Fraser’s Mag.’ , Aug. 1870, p. 257) advances arguments
  on the other side. Sir C. Lyell had already (‘Principles of
  Geology,’ vol. ii. 1868, p. 489) called attention, in a
  striking passage, to the evil influence of the Holy Inquisition
  in having lowered, through selection, the general standard of
  intelligence in Europe.

  [247] Mr. Galton, ‘Macmillan’s Magazine,’ August, 1865, p. 325.
  See, also, ‘Nature,’ “On Darwinism and National Life,” Dec.
  1869, p. 184.

  [248] ‘Last Winter in the United States,’ 1868, p. 29.

  [249] ‘On the Origin of Civilisation,’ ‘Proc. Ethnological
  Soc.’ Nov. 26, 1867.

  [250] ‘Primeval Man,’ 1869.

  [251] ‘Royal Institution of Great Britain,’ March 15, 1867.
  Also, ‘Researches into the Early History of Mankind,’ 1865.

  [252] ‘Primitive Marriage,’ 1865. See, likewise, an excellent
  article, evidently by the same author, in the ‘North British
  Review,’ July, 1869. Also, Mr. L. H. Morgan, “A Conjectural
  Solution of the Origin of the Class. System of Relationship,”
  in ‘Proc. American Acad. of Sciences,’ vol. vii. Feb. 1868.
  Prof. Schaaffhausen (‘Anthropolog. Review,’ Oct. 1869, p. 373)
  remarks on “the vestiges of human sacrifices found both in
  Homer and the Old Testament.”

  [253] Sir J. Lubbock, ‘Prehistoric Times,’ 2nd edit. 1869,
  chap. xv. and xvi. _et passim_.

  [254] Dr. F. Müller has made some good remarks to this effect
  in the ‘Reise der Novara: Anthropolog. Theil,’ Abtheil. iii.
  1868, s. 127.

  [255] Isidore Geoffroy St.-Hilaire gives a detailed account of
  the position assigned to man by various naturalists in their
  classifications: ‘Hist. Nat. Gén.’ tom. ii. 1859, p. 170-189.

  [256] See the very interesting article, “L’Instinct chez les
  Insectes,” by M. George Pouchet, ‘Revue des Deux Mondes,’ Feb.
  1870, p. 682.

  [257] Westwood, ‘Modern Class. of Insects,’ vol. ii. 1840, p.

  [258] ‘Proc. Zoolog. Soc.’ 1869, p. 4.

  [259] ‘Evidence as to Man’s Place in Nature,’ 1863, p. 70, _et

  [260] Isid. Geoffroy, ‘Hist. Nat. Gén.’ tom. ii. 1859, p. 217.

  [261] “Ueber die Richtung der Haare,” &c., Müller’s ‘Archiv für
  Anat. und Phys.’ 1837, s. 51.

  [262] On the hair in Hylobates, see ‘Nat. Hist. of Mammals,’ by
  C. L. Martin, 1841, p. 415. Also, Isid. Geoffroy on the
  American monkeys and other kinds, ‘Hist. Nat. Gén.’ vol. ii.
  1859, p. 216, 243. Eschricht, ibid., s. 46, 55, 61. Owen, ‘Anat.
  of Vertebrates,’ vol. iii. p. 619. Wallace, ‘Contributions to
  the Theory of Natural Selection,’ 1870. p. 344.

  [263] ‘Origin of Species,’ 5th edit. 1869, p. 194. ‘The
  Variation of Animals and Plants under Domestication,’ vol. ii.
  1868, p. 348.

  [264] ‘An Introduction to the Classification of Animals,’ 1869,
  p. 99.

  [265] This is nearly the same classification as that
  provisionally adopted by Mr. St. George Mivart (‘Transact.
  Philosoph. Soc.’ 1867, p. 300), who, after separating the
  Lemuridæ, divides the remainder of the Primates into the
  Hominidæ, the Simiadæ answering to the Catarhines, the Cebidæ,
  and the Hapalidæ,—these two latter groups answering to the

  [266] ‘Transact. Zoolog. Soc.’ vol. vi. 1867, p. 214.

  [267] Mr. St. G. Mivart, ‘Transact. Phil. Soc.’ 1867, p. 410.

  [268] Messrs. Murie and Mivart on the Lemuroidea. ‘Transact.
  Zoolog. Soc.’ vol. vii. 1869, p. 5.

  [269] Häckel has come to this same conclusion. See ‘Ueber die
  Entstehung des Menschengeschlechts,’ in Virchow’s ‘Sammlung.
  gemein. wissen. Vorträge,’ 1868, s. 61. Also his ‘Natürliche
  Schöpfungsgeschichte,’ 1868, in which he gives in detail his
  views on the genealogy of man.

  [270] ‘Anthropological Review,’ April, 1867, p. 236.

  [271] ‘Elements of Geology,’ 1865, p. 583-585. ‘Antiquity of
  Man’, 1863; p. 145.

  [272] ‘Man’s Place in Nature,’ p. 105.

  [273] Elaborate tables are given in his ‘Generelle Morphologie’
  (B. ii. s. cliii. and s. 425); and with more especial reference
  to man in his ‘Natürliche Schöpfungsgeschichte,’ 1868. Prof.
  Huxley, in reviewing this latter work (‘The Academy,’ 1869, p.
  42) says, that he considers the phylum or lines of descent of
  the Vertebrata to be admirably discussed by Häckel, although he
  differs on some points. He expresses, also, his high estimate
  of the value of the general tenor and spirit of the whole work.

  [274] ‘Palæontology,’ 1860, p. 199.

  [275] I had the satisfaction of seeing, at the Falkland
  Islands, in April, 1833, and therefore some years before any
  other naturalist, the locomotive larvæ of a compound Ascidian,
  closely allied to, but apparently generically distinct from,
  Synoicum. The tail was about five times as long as the oblong
  head, and terminated in a very fine filament. It was plainly
  divided, as sketched by me under a simple microscope, by
  transverse opaque partitions, which I presume represent the
  great cells figured by Kowalevsky. At an early stage of
  development the tail was closely coiled round the head of the

  [276] ‘Mémoires de l’Acad. des Sciences de St. Pétersbourg,’
  tom. x. No. 15, 1866.

  [277] This is the conclusion of one of the highest authorities
  in comparative anatomy, namely, Prof. Gegenbaur: ‘Grundzüge der
  vergleich. Anat.’ 1870, s. 876. The result has been arrived at
  chiefly from the study of the Amphibia; but it appears from the
  researches of Waldeyer (as quoted in Humphry’s ‘Journal of
  Anat. and Phys.’ 1869, p. 161), that the sexual organs of even
  “the higher vertebrata are, in their early condition,
  hermaphrodite.” Similar views have long been held by some
  authors, though until recently not well based.

  [278] The male Thylacinus offers the best instance. Owen,
  ‘Anatomy of Vertebrates,’ vol. iii. p. 771.

  [279] Serranus is well known often to be in an hermaphrodite
  condition; but Dr. Günther informs me that he is convinced that
  this is not its normal state. Descent from an ancient
  androgynous prototype would, however, naturally favour and
  explain, to a certain extent, the recurrence of this condition
  in these fishes.

  [280] Mr. Lockwood believes (as quoted in ‘Quart. Journal of
  Science,’ April, 1868, p. 269), from what he has observed of
  the development of Hippocampus, that the walls of the abdominal
  pouch of the male in some way afford nourishment. On male
  fishes hatching the ova in their mouths, see a very interesting
  paper by Prof. Wyman, in ‘Proc. Boston Soc. of Nat. Hist.’
  Sept. 15, 1857; also Prof. Turner, in ‘Journal of Anat. and
  Phys.’ Nov. 1, 1866, p. 78. Dr. Günther has likewise described
  similar cases.

  [281] All vital functions tend to run their course in fixed and
  recurrent periods, and with tidal animals the periods would
  probably be lunar; for such animals must have been left dry or
  covered deep with water,—supplied with copious food or
  stinted,—during endless generations, at regular lunar
  intervals. If then the Vertebrata are descended from an animal
  allied to the existing tidal Ascidians, the mysterious fact,
  that with the higher and now terrestrial Vertebrata, not to
  mention other classes, many normal and abnormal vital processes
  run their course according to lunar periods, is rendered
  intelligible. A recurrent period, if approximately of the right
  duration, when once gained, would not, as far as we can judge,
  be liable to be changed; consequently it might be thus
  transmitted during almost any number of generations. This
  conclusion, if it could be proved sound, would be curious; for
  we should then see that the period of gestation in each mammal,
  and the hatching of each bird’s eggs, and many other vital
  processes, still betrayed the primordial birthplace of these

  [282] ‘History of India,’ 1841, vol. i. p. 323. Father Ripa
  makes exactly the same remark with respect to the Chinese.

  [283] A vast number of measurements of Whites, Blacks, and
  Indians, are given in the ‘Investigations in the Military and
  Anthropolog. Statistics of American Soldiers,’ by B. A. Gould,
  1869, p. 298-358; on the capacity of the lungs, p. 471. See
  also the numerous and valuable tables, by Dr. Weisbach, from
  the observations of Dr. Scherzer and Dr. Schwarz, in the ‘Reise
  der Novara: Anthropolog. Theil,’ 1867.

  [284] See, for instance, Mr. Marshall’s account of the brain of
  a Bush-woman, in ‘Phil. Transact.’ 1864, p. 519.

  [285] Wallace, ‘The Malay Archipelago,’ vol. ii. 1869, p. 178.

  [286] With respect to the figures in the famous Egyptian caves
  of Abou-Simbel, M. Pouchet says (‘The Plurality of the Human
  Races,’ Eng. translat. 1864, p. 50), that he was far from
  finding recognisable representations of the dozen or more
  nations which some authors believe that they can recognise.
  Even some of the most strongly-marked races cannot be
  identified with that degree of unanimity which might have been
  expected from what has been written on the subject. Thus
  Messrs. Nott and Gliddon (‘Types of Mankind,’ p. 148) state
  that Rameses II., or the Great, has features superbly European;
  whereas Knox, another firm believer in the specific distinction
  of the races of man (‘Races of Man,’ 1850, p. 201), speaking of
  young Memnon (the same person with Rameses II., as I am
  informed by Mr. Birch) insists in the strongest manner that he
  is identical in character with the Jews of Antwerp. Again,
  whilst looking in the British Museum with two competent judges,
  officers of the establishment, at the statue of Amunoph III.,
  we agreed that he had a strongly negro cast of features; but
  Messrs. Nott and Gliddon (ibid. p. 146, fig. 53) describe him
  as “a hybrid, but not of negro intermixture.”

  [287] As quoted by Nott and Gliddon, ‘Types of Mankind,’ 1854,
  p. 439. They give also corroborative evidence; but C. Vogt
  thinks that the subject requires further investigation.

  [288] “Diversity of Origin of the Human Races,” in the
  ‘Christian Examiner,’ July, 1850.

  [289] ‘Transact. B. Soc. of Edinburgh,’ vol. xxii. 1861, p.

  [290] ‘On the Phenomena of Hybridity in the Genus Homo,’ Eng.
  translat. 1864.

  [291] See the interesting letter by Mr. T. A. Murray, in the
  ‘Anthropolog. Review,’ April, 1868, p. liii. In this letter
  Count Strzelecki’s statement, that Australian women who have
  borne children to a white man are afterwards sterile with their
  own race, is disproved. M. A. de Quatrefages has also collected
  (‘Revue des Cours Scientifiques,’ March, 1869, p. 239) much
  evidence that Australians and Europeans are not sterile when

  [292] ‘An Examination of Prof. Agassiz’s Sketch of the Nat.
  Provinces of the Animal World,’ Charleston, 1855, p. 44.

  [293] ‘Military and Anthropolog. Statistics of American
  Soldiers,’ by B. A. Gould, 1869, p. 319.

  [294] ‘The Variation of Animals and Plants under
  Domestication,’ vol. ii. p. 109. I may here remind the reader
  that the sterility of species when crossed is not a
  specially-acquired quality; but, like the incapacity of certain
  trees to be grafted together, is incidental on other acquired
  differences. The nature of these differences is unknown, but
  they relate more especially to the reproductive system, and
  much less to external structure or to ordinary differences in
  constitution. One important element in the sterility of crossed
  species apparently lies in one or both having been long
  habituated to fixed conditions; for we know that changed
  conditions have a special influence on the reproductive system,
  and we have good reason to believe (as before remarked) that
  the fluctuating conditions of domestication tend to eliminate
  that sterility which is so general with species in a natural
  state when crossed. It has elsewhere been shewn by me (ibid.
  vol. ii. p. 185, and ‘Origin of Species,’ 5th edit. p. 317)
  that the sterility of crossed species has not been acquired
  through natural selection: we can see that when two forms have
  already been rendered very sterile, it is scarcely possible
  that their sterility should be augmented by the preservation or
  survival of the more and more sterile individuals; for as the
  sterility increases fewer and fewer offspring will be produced
  from which to breed, and at last only single individuals will
  be produced, at the rarest intervals. But there is even a
  higher grade of sterility than this. Both Gärtner and Kölreuter
  have proved that in genera of plants including numerous
  species, a series can be formed from species which when crossed
  yield fewer and fewer seeds, to species which never produce a
  single seed, but yet are affected by the pollen of the other
  species, for the germen swells. It is here manifestly
  impossible to select the more sterile individuals, which have
  already ceased to yield seeds; so that the acme of sterility,
  when the germen alone is affected, cannot be gained through
  selection. This acme, and no doubt the other grades of
  sterility, are the incidental results of certain unknown
  differences in the constitution of the reproductive system of
  the species which are crossed.

  [295] ‘The Variation of Animals,’ &c., vol. ii. p. 92.

  [296] M. de Quatrefages has given (‘Anthropolog. Review,’ Jan.
  1869, p. 22) an interesting account of the success and energy
  of the Paulistas in Brazil, who are a much crossed race of
  Portuguese and Indians, with a mixture of the blood of other

  [297] For instance with the aborigines of America and
  Australia. Prof. Huxley says (‘Transact. Internat. Congress of
  Prehist. Arch.’ 1868. p. 105) that the skulls of many South
  Germans and Swiss are “as short and as broad as those of the
  Tartars,” &c.

  [298] See a good discussion on this subject in Waitz,
  ‘Introduct. to Anthropology,’ Eng. translat. 1863, p. 198-208,
  227. I have taken some of the above statements from H. Tuttle’s
  ‘Origin and Antiquity of Physical Man,’ Boston, 1866, p. 35.

  [299] Prof. Nägeli has carefully described several striking
  cases in his ‘Botanische Mittheilungen,’ B. ii. 1866, s.
  294-369. Prof. Asa Gray has made analogous remarks on some
  intermediate forms in the Compositæ of N. America.

  [300] ‘Origin of Species,’ 5th edit. p. 68.

  [301] See Prof. Huxley to this effect in the ‘Fortnightly
  Review,’ 1865, p. 275.

  [302] ‘Lectures on Man,’ Eng. translat. 1864, p. 468.

  [303] ‘Die Racen des Schweines,’ 1860, s. 46. ‘Vorstudien für
  Geschichte, &c., Schweineschädel,’ 1864, s. 104. With respect
  to cattle, see M. de Quatrefages, ‘Unité de l’Espèce Humaine,’
  1861, p. 119.

  [304] Tylor’s ‘Early History of Mankind,’ 1865; for the
  evidence with respect to gesture-language, see p. 54. Lubbock’s
  ‘Prehistoric Times,’ 2nd edit. 1869.

  [305] ‘The Primitive Inhabitants of Scandinavia,’ Eng.
  translat. edited by Sir J. Lubbock, 1868, p. 104.

  [306] Hodder M. Westropp, on Cromlechs, &c., ‘Journal of
  Ethnological Soc.’ as given in ‘Scientific Opinion,’ June 2nd.
  1869, p. 3.

  [307] ‘Journal of Researches: Voyage of the “Beagle,”’ p. 46.

  [308] ‘Prehistoric Times,’ 1869, p. 574.

  [309] Translation in ‘Anthropological Review,’ Oct. 1868, p.

  [310] ‘Transact. Internat. Congress of Prehistoric Arch.’ 1868,
  p. 172-175. See also Broca (translation) in ‘Anthropological
  Review,’ Oct. 1868, p. 410.

  [311] Dr. Gerland, ‘Ueber das Aussterben der Naturvölker,’
  1868, s. 82.

  [312] Gerland (ibid. s. 12) gives facts in support of this

  [313] See remarks to this effect in Sir H. Holland’s ‘Medical
  Notes and Reflections,’ 1839, p. 390.

  [314] I have collected (‘Journal of Researches, Voyage of the
  “Beagle,”’ p. 435) a good many cases bearing on this subject:
  see also Gerland, ibid. s. 8. Poeppig speaks of the “breath of
  civilisation as poisonous to savages.”

  [315] Sproat, ‘Scenes and Studies of Savage Life,’ 1868, p.

  [316] Bagehot, “Physics and Politics,” ‘Fortnightly Review,’
  April 1, 1868, p. 455.

  [317] “On Anthropology,” translation, ‘Anthropolog. Review,’
  Jan. 1868, p. 38.

  [318] ‘The Annals of Rural Bengal,’ 1868, p. 134.

  [319] ‘The Variation of Animals and Plants under
  Domestication,’ vol. ii. p. 95.

  [320] Pallas, ‘Act. Acad. St. Petersburgh,’ 1780, part ii. p.
  69. He was followed by Rudolphi, in his ‘Beyträge zur
  Anthropologie,’ 1812. An excellent summary of the evidence is
  given by Godron, ‘De l’Espèce,’ 1859, vol. ii. p. 246, &c.

  [321] Sir Andrew Smith, as quoted by Knox, ‘Races of Man,’
  1850, p. 473.

  [322] See De Quatrefages on this head, ‘Revue des Cours
  Scientifiques,’ Oct. 17, 1868, p. 731.

  [323] Livingstone’s ‘Travels and Researches in S. Africa,’
  1857, p. 338, 329. D’Orbigny, as quoted by Godron, ‘De
  l’Espèce,’ vol. ii. p. 266.

  [324] See a paper read before the Royal Soc. in 1813, and
  published in his Essays in 1818. I have given an account of Dr.
  Wells’ views in the Historical Sketch (p. xvi) to my ‘Origin of
  Species.’ Various cases of colour correlated with
  constitutional peculiarities are given in my ‘Variation of
  Animals under Domestication,’ vol. ii. p. 227, 335.

  [325] See, for instance, Nott and Gliddon, ‘Types of Mankind,’
  p. 68.

  [326] Major Tulloch, in a paper read before the Statistical
  Society, April 20th, 1840, and given in the ‘Athenæum,’ 1840,
  p. 353.

  [327] ‘The Plurality of the Human Race’ (translat.), 1864, p.

  [328] Quatrefages, ‘Unité de l’Espèce Humaine,’ 1861, p. 205.
  Waitz, ‘Introduct. to Anthropology,’ translat. vol. i. 1863, p.
  124. Livingstone gives analogous cases in his ‘Travels.’

  [329] In the spring of 1862 I obtained permission from the
  Director-General of the Medical department of the Army, to
  transmit to the surgeons of the various regiments on foreign
  service a blank table, with the following appended remarks, but
  I have received no returns. “As several well-marked cases have
  been recorded with our domestic animals of a relation between
  the colour of the dermal appendages and the constitution; and
  it being notorious that there is some limited degree of
  relation between the colour of the races of man and the climate
  inhabited by them; the following investigation seems worth
  consideration. Namely, whether there is any relation in
  Europeans between the colour of their hair, and their liability
  to the diseases of tropical countries. If the surgeons of the
  several regiments, when stationed in unhealthy tropical
  districts, would be so good as first to count, as a standard of
  comparison, how many men, in the force whence the sick are
  drawn, have dark and light-coloured hair, and hair of
  intermediate or doubtful tints; and if a similar account were
  kept by the same medical gentlemen, of all the men who suffered
  from malarious and yellow fevers, or from dysentery, it would
  soon be apparent, after some thousand cases had been tabulated,
  whether there exists any relation between the colour of the
  hair and constitutional liability to tropical diseases. Perhaps
  no such relation would be discovered, but the investigation is
  well worth making. In case any positive result were obtained,
  it might be of some practical use in selecting men for any
  particular service. Theoretically the result would be of high
  interest, as indicating one means by which a race of men
  inhabiting from a remote period an unhealthy tropical climate,
  might have become dark-coloured by the better preservation of
  dark-haired or dark-complexioned individuals during a long
  succession of generations.”

  [330] ‘Anthropological Review,’ Jan. 1866, p. xxi.

  [331] See, for instance, Quatrefages (‘Revue des Cours
  Scientifiques,’ Oct. 10, 1868, p. 724) on the effects of
  residence in Abyssinia and Arabia, and other analogous cases.
  Dr. Rolle (‘Der Mensch, seine Abstammung,’ &c., 1865, s. 99)
  states, on the authority of Khanikof, that the greater number
  of German families settled in Georgia, have acquired in the
  course of two generations dark hair and eyes. Mr. D. Forbes
  informs me that the Quichuas in the Andes vary greatly in
  colour, according to the position of the valleys inhabited by

  [332] Harlan, ‘Medical Researches,’ p. 532. Quatrefages (‘Unité
  de l’Espèce Humaine,’ 1861, p. 128) has collected much evidence
  on this head.

  [333] See Prof. Schaaffhausen, translat. in ‘Anthropological
  Review,’ Oct. 1868, p. 429.

  [334] Mr. Catlin states (‘N. American Indians,’ 3rd edit. 1842,
  vol. i. p. 49) that in the whole tribe of the Mandans, about
  one in ten or twelve of the members of all ages and both sexes
  have bright silvery grey hair, which is hereditary. Now this
  hair is as coarse and harsh as that of a horse’s mane, whilst
  the hair of other colours is fine and soft.

  [335] On the odour of the skin, Godron, ‘Sur l’Espèce,’ tom.
  ii. p. 217. On the pores in the skin, Dr. Wilckens, ‘Die
  Aufgaben der landwirth. Zootechnik,’ 1869, s. 7.

  [336] Westwood, ‘Modern Class. of Insects,’ vol. ii. 1810, p.
  541. In regard to the statement about Tanais, mentioned below,
  I am indebted to Fritz Müller.

  [337] Kirby and Spence, ‘Introduction to Entomology,’ vol. iii.
  1826, p. 309.

  [338] Even with those of plants in which the sexes are
  separate, the male flowers are generally mature before the
  female. Many hermaphrodite plants are, as first shewn by C. K.
  Sprengel, dichogamous; that is, their male and female organs
  are not ready at the same time, so that they cannot be
  self-fertilised. Now with such plants the pollen is generally
  mature in the same flower before the stigma, though there are
  some exceptional species in which the female organs are mature
  before the male.

  [339] I have received information, hereafter to be given, to
  this effect with respect to poultry. Even with birds, such as
  pigeons, which pair for life, the female, as I hear from Mr.
  Jenner Weir, will desert her mate if he is injured or grows

  [340] On the Gorilla, Savage and Wyman, ‘Boston Journal of Nat.
  Hist.’ vol. v. 1845-47, p. 423. On Cynocephalus, Brehm,
  ‘Illust. Thierleben,’ B. i. 1864, s. 77. On Mycetes, Rengger,
  ‘Naturgesch.: Säugethiere von Paraguay,’ 1830, s. 14, 20. On
  Cebus, Brehm, ibid. s. 108.

  [341] Pallas, ‘Spicilegia Zoolog.’ Fasc. xii. 1777, p. 29. Sir
  Andrew Smith, ‘Illustrations of the Zoology of S. Africa,’
  1849, pl. 29, on the Kobus. Owen, in his ‘Anatomy of
  Vertebrates’ (vol. iii. 1868, p. 633) gives a table
  incidentally showing which species of Antelopes pair and which
  are gregarious.

  [342] Dr. Campbell, in ‘Proc. Zoolog. Soc.’ 1869, p. 138. See
  also an interesting paper, by Lieut. Johnstone, in ‘Proc.
  Asiatic Soc. of Bengal,’ May, 1868.

  [343] ‘The Ibis,’ vol. iii. 1861, p. 133, on the Progne
  Widow-bird. See also on the Vidua axillaris, ibid. vol. ii.
  1860, p. 211. On the polygamy of the Capercailzie and Great
  Bustard, see L. Lloyd, ‘Game Birds of Sweden,’ 1867, p. 19, and
  182. Montagu and Selby speak of the Black Grouse as polygamous
  and of the Red Grouse as monogamous.

  [344] The Rev. E. S. Dixon, however, speaks positively
  (‘Ornamental Poultry,’ 1848, p. 76) about the eggs of the
  guinea-fowl being infertile when more than one female is kept
  with the same male.

  [345] Noel Humphreys, ‘River Gardens,’ 1857.

  [346] Kirby and Spence, ‘Introduction to Entomology,’ vol. iii.
  1826, p. 342.

  [347] One parasitic Hymenopterous insect (Westwood, ‘Modern
  Class. of Insects,’ vol. ii, p. 160) forms an exception to the
  rule, as the male has rudimentary wings, and never quits the
  cell in which it is born, whilst the female has well-developed
  wings. Audouin believes that the females are impregnated by the
  males which are born in the same cells with them; but it is
  much more probable that the females visit other cells, and thus
  avoid close inter-breeding. We shall hereafter meet with a few
  exceptional cases, in various classes, in which the female,
  instead of the male, is the seeker and wooer.

  [348] ‘Essays and Observations,’ edited by Owen, vol. i. 1861,
  p. 194.

  [349] Prof. Sachs (‘Lehrbuch der Botanik,’ 1870, s. 633) in
  speaking of the male and female reproductive cells, remarks,
  “verhält sich die eine bei der Vereinigung activ, ... die
  andere erscheint bei der Vereinigung passiv.”

  [350] ‘Reise der Novara: Anthropolog. Theil,’ 1867, s. 216-269.
  The results were calculated by Dr. Weisbach from measurements
  made by Drs. K. Scherzer and Schwarz. On the greater
  variability of the males of domesticated animals, see my
  ‘Variation of Animals and Plants under Domestication,’ vol. ii.
  1868, p. 75.

  [351] ‘Proceedings Royal Soc.’ vol. xvi. July, 1868, p. 519 and

  [352] ‘Proc. Royal Irish Academy,’ vol. x. 1868, p. 123.

  [353] ‘Massachusetts Medical Soc.’ vol. ii. No. 3, 1808, p. 9.

  [354] ‘The Variation of Animals and Plants under
  Domestication,’ vol. ii. 1868, p. 75. In the last chapter but
  one, the provisional hypothesis of pangenesis, above alluded
  to, is fully explained.

  [355] These facts are given on the high authority of a great
  breeder, Mr. Teebay, in Tegetmeier’s ‘Poultry Book,’ 1868, p.
  158. On the characters of chickens of different breeds, and on
  the breeds of the pigeon, alluded to in the above paragraph,
  see ‘Variation of Animals,’ &c., vol. i. p. 160, 249; vol. ii.
  p. 77.

  [356] ‘Novæ species Quadrupedum e Glirium ordine,’ 1778, p. 7.
  On the transmission of colour by the horse, see ‘Variation of
  Animals, &c. under Domestication,’ vol. i. p. 21. Also vol. ii.
  p. 71, for a general discussion on Inheritance as limited by

  [357] Dr. Chapuis, ‘Le Pigeon Voyageur Belge,’ 1865, p. 87.
  Boitard et Corbié, ‘Les Pigeons de Volière,’ &c., 1824, p. 173.

  [358] References are given in my ‘Variation of Animals under
  Domestication,’ vol. ii. p. 72.

  [359] I am much obliged to Mr. Cupples for having made
  enquiries for me in regard to the Roebuck and Red Deer of
  Scotland from Mr. Robertson, the experienced head-forester to
  the Marquis of Breadalbane. In regard to Fallow-deer, I am
  obliged to Mr. Eyton and others for information. For the
  _Cervus alces_ of N. America, see ‘Land and Water,’ 1868, p.
  221 and 254; and for the _C. Virginianus_ and _strongyloceros_
  of the same continent, see J. D. Caton, in ‘Ottawa Acad. of
  Nat. Sc.’ 1868, p. 13. For _Cervus Eldi_ of Pegu, see Lieut.
  Beavan, ‘Proc. Zoolog. Soc.’ 1867, p. 762.

  [360] _Antilocapra Americana._ Owen, ‘Anatomy of Vertebrates,’
  vol. iii. p. 627.

  [361] I have been assured that the horns of the sheep in North
  Wales can always be felt, and are sometimes even an inch in
  length, at birth. With cattle Youatt says (‘Cattle,’ 1834, p.
  277) that the prominence of the frontal bone penetrates the
  cutis at birth, and that the horny matter is soon formed over

  [362] I am greatly indebted to Prof. Victor Carus for having
  made inquiries for me, from the highest authorities, with
  respect to the merino sheep of Saxony. On the Guinea coast of
  Africa there is a breed of sheep in which, as with merinos, the
  rams alone bear horns; and Mr. Winwood Reade informs me that in
  the one case observed, a young ram born on Feb. 10th first
  showed horns on March 6th, so that in this instance the
  development of the horns occurred at a later period of life,
  conformably with our rule, than in the Welsh sheep, in which
  both sexes are horned.

  [363] In the common peacock (_Pavo cristatus_) the male alone
  possesses spurs, whilst both sexes of the Java peacock (_P.
  muticus_) offer the unusual case of being furnished with spurs.
  Hence I fully expected that in the latter species they would
  have been developed earlier in life than in the common peacock;
  but M. Hegt of Amsterdam informs me, that with young birds of
  the previous year, belonging to both species, compared on April
  23rd, 1869, there was no difference in the development of the
  spurs. The spurs, however, were as yet represented merely by
  slight knobs or elevations. I presume that I should have been
  informed if any difference in the rate of development had
  subsequently been observed.

  [364] In some other species of the Duck Family the speculum in
  the two sexes differs in a greater degree; but I have not been
  able to discover whether its full development occurs later in
  life in the males of such species, than in the male of the
  common duck, as ought to be the case according to our rule.
  With the allied _Mergus cucullatus_ we have, however, a case of
  this kind: the two sexes differ conspicuously in general
  plumage, and to a considerable degree in the speculum, which is
  pure white in the male and greyish-white in the female. Now the
  young males at first resemble, in all respects, the female, and
  have a greyish-white speculum, but this becomes pure white at
  an earlier age than that at which the adult male acquires his
  other more strongly-marked sexual differences in plumage: see
  Audubon, ‘Ornithological Biography,’ vol. iii. 1835, p.

  [365] ‘Das Ganze der Taubenzucht,’ 1837, s. 21, 24. For the
  case of the streaked pigeons, see Dr. Chapuis, ‘Le Pigeon
  Voyageur Belge.’ 1865, p. 87.

  [366] For full particulars and references on all these points
  respecting the several breeds of the Fowl, see ‘Variation of
  Animals and Plants under Domestication,’ vol. i. p. 250, 256.
  In regard to the higher animals, the sexual differences which
  have arisen under domestication are described in the same work
  under the head of each species.

  [367] ‘Twenty-ninth Annual Report of the Registrar-General for
  1866.’ In this report (p. xii) a special decennial table is

  [368] For Norway and Russia, see abstract of Prof. Faye’s
  researches, in ‘British and Foreign Medico-Chirurg. Review,’
  April, 1867, p. 343, 345. For France, the ‘Annuaire pour l’An
  1867.’ p. 213.

  [369] In regard to the Jews, see M. Thury, ‘La Loi de
  Production des Sexes,’ 1863, p. 25.

  [370] Babbage, ‘Edinburgh Journal of Science,’ 1829, vol. i. p.
  88; also p. 90, on still-born children. On illegitimate
  children in England, see ‘Report of Registrar-General for
  1866,’ p. xv.

  [371] ‘British and Foreign Medico-Chirurg. Review,’ April,
  1867, p. 343. Dr. Stark also remarks (‘Tenth Annual Report of
  Births, Deaths, &c., in Scotland,’ 1867, p. xxviii) that “These
  examples may suffice to shew that, at almost every stage of
  life, the males in Scotland have a greater liability to death
  and a higher death-rate than the females. The fact, however, of
  this peculiarity being most strongly developed at that
  infantile period of life when the dress, food, and general
  treatment of both sexes are alike, seems to prove that the
  higher male death-rate is an impressed, natural, and
  constitutional peculiarity due to sex alone.”

  [372] With the savage Guaranys of Paraguay, according to the
  accurate Azara (‘Voyages dans l’Amérique mérid.’ tom. ii. 1809,
  p. 60, 179), the women in proportion to the men are as 14 to

  [373] Leuckart in Wagner, ‘Handwörterbuch der Phys.’ B. iv.
  1853, s. 774.

  [374] Anthropological Review, April, 1870, p. cviii.

  [375] During the last eleven years a record has been kept of
  the number of mares which have proved barren or prematurely
  slipped their foals; and it deserves notice, as shewing how
  infertile these highly-nurtured and rather closely-interbred
  animals have become, that not far from one-third of the mares
  failed to produce living foals. Thus during 1866, 809 male
  colts and 816 female colts were born, and 743 mares failed to
  produce offspring. During 1867, 836 males and 902 females were
  born, and 794 mares failed.

  [376] I am much indebted to Mr. Cupples for having procured for
  me the above returns from Scotland, as well as some of the
  following returns on cattle. Mr. R. Elliot, of Laighwood, first
  called my attention to the premature deaths of the males,—a
  statement subsequently confirmed by Mr. Aitchison and others.
  To this latter gentleman, and to Mr. Payan, I owe my thanks for
  the larger returns on sheep.

  [377] Bell, ‘History of British Quadrupeds,’ p. 100.

  [378] ‘Illustrations of the Zoology of S. Africa,’ 1849, pl.

  [379] Brehm (‘Illust. Thierleben,’ B. iv. s. 990) comes to the
  same conclusion.

  [380] On the authority of L. Lloyd, ‘Game Birds of Sweden,’
  1867, p. 12, 132.

  [381] ‘Nat. Hist. of Selbourne,’ letter xxix. edit. of 1825,
  vol. i. p. 139.

  [382] Mr. Jenner Weir received similar information, on making
  enquiries during the following year. To shew the number of
  chaffinches caught, I may mention that in 1869 there was a
  match between two experts; and one man caught in a day 62, and
  another 40, male chaffinches. The greatest number ever caught
  by one man in a single day was 70.

  [383] ‘Ibis,’ vol. ii. p. 260, as quoted in Gould’s
  ‘Trochilidæ,’ 1861, p. 52. For the foregoing proportions, I am
  indebted to Mr. Salvin for a table of his results.

  [384] ‘Ibis,’ 1860, p. 137; and 1867, p. 369.

  [385] ‘Ibis,’ 1862, p. 137.

  [386] Leuckart quotes Bloch (Wagner, ‘Handwörterbuch der Phys.’
  B. iv. 1853, s. 775), that with fish there are twice as many
  males as females.

  [387] Quoted in the ‘Farmer,’ March 18, 1869, p. 369.

  [388] ‘The Stormontfield Piscicultural Experiments,’ 1866, p.
  23. The ‘Field’ newspaper, June 29th, 1867.

  [389] ‘Land and Water,’ 1868, p. 41.

  [390] Yarrell, ‘Hist. British Fishes,’ vol. i. 1836, p. 307; on
  the _Cyprinus carpio_, p. 331; on the _Tinca vulgaris_, p. 331;
  on the _Abramis brama_, p. 336. See, for the minnow (_Leuciscus
  phoxinus_), ‘Loudon’s Mag. of Nat. Hist.’ vol. v. 1832, p. 682.

  [391] Leuckart quotes Meinecke (Wagner, ‘Handwörterbuch der
  Phys.’ B. iv. 1853, s. 775) that with Butterflies the males are
  three or four times as numerous as the females.

  [392] ‘The Naturalist on the Amazons,’ vol. ii. 1863, p. 228,

  [393] Four of these cases are given by Mr. Trimen in his
  ‘Rhopalocera Africæ Australis.’

  [394] Quoted by Trimen, ‘Transact. Ent. Soc.’ vol. v. part iv.
  1866, p. 330.

  [395] ‘Transact. Linn. Soc.’ vol. xxv. p. 37.

  [396] ‘Proc. Entomolog. Soc.’ Feb. 17th, 1868.

  [397] Quoted by Dr. Wallace in ‘Proc. Ent. Soc.’ 3rd series,
  vol. v. 1867, p. 487.

  [398] Blanchard, ‘Metamorphoses, Mœurs des Insectes,’ 1868, p.

  [399] ‘Lepidopteren-Doubblettren Liste,’ Berlin, No. x. 1866.

  [400] This naturalist has been so kind as to send me some
  results from former years, in which the females seemed to
  preponderate; but so many of the figures were estimates, that I
  found it impossible to tabulate them.

  [401] Günther’s ‘Record of Zoological Literature,’ 1867, p.
  260. On the excess of female Lucanus, ibid. p. 250. On the
  males of Lucanus in England, Westwood, ‘Modern Class. of
  Insects,’ vol. i. p. 187. On the Siagonium, ibid. p. 172.

  [402] Walsh, in ‘The American Entomologist,’ vol. i. 1869, p.
  103. F. Smith, ‘Record of Zoological Literature,’ 1867, p. 328.

  [403] ‘Farm Insects,’ p. 45-46.

  [404] ‘Observations on N. American Neuroptera,’ by H. Hagen and
  B. D. Walsh, ‘Proc. Ent. Soc. Philadelphia,’ Oct. 1863, p. 168,
  223, 239.

  [405] ‘Proc. Ent. Soc. London,’ Feb. 17, 1868.

  [406] Another great authority in this class, Prof. Thorell of
  Upsala (‘On European Spiders,’ 1869-70, part i. p. 205) speaks
  as if female spiders were generally commoner than the males.

  [407] See, on this subject, Mr. Pickard-Cambridge, as quoted in
  ‘Quarterly Journal of Science,’ 1868, p. 429.

  [408] I have often been struck with the fact, that in several
  species of Primula the seeds in the capsules which contained
  only a few were very much larger than the numerous seeds in the
  more productive capsules.

  [409] ‘Principles of Biology,’ vol. ii. 1867, chaps. ii.-xi.

  [410] ‘De l’Espèce et de la Class.’ &c., 1869, p. 106.

  [411] See, for instance, the account which I have given in my
  ‘Journal of Researches,’ 1845, p. 7.

  [412] I have given (‘Geolog. Observations on Volcanic Islands,’
  1844, p. 53) a curious instance of the influence of light on
  the colours of a frondescent incrustation, deposited by the
  surf on the coast-rocks of Ascension, and formed by the
  solution of triturated sea-shells.

  [413] ‘Facts and Arguments for Darwin,’ English translat. 1869,
  p. 20. See the previous discussion on the olfactory threads.
  Sars has described a somewhat analogous case (as quoted in
  ‘Nature,’ 1870, p. 455) in a Norwegian crustacean, the
  _Pontoporeia affinis_.

  [414] See Sir J. Lubbock in ‘Annals. and Mag. of Nat. Hist.’
  vol. xi. 1853, pl. i. and x.; and vol. xii. (1853) pl. vii. See
  also Lubbock in ‘Transact. Ent. Soc.’ vol. iv. new series,
  1856-1858, p. 8. With respect to the zigzagged antennæ
  mentioned below, see Fritz Müller, ‘Facts and Arguments for
  Darwin’ 1869, p. 40, foot-note.

  [415] See a paper by Mr. C. Spence Bate, with figures, in
  ‘Proc. Zoolog. Soc.’ 1868, p. 363; and on the nomenclature of
  the genus, ibid. p. 585. I am greatly indebted to Mr. Spence
  Bate for nearly all the above statements with respect to the
  chelæ of the higher crustaceans.

  [416] ‘Hist. Nat. des Crust.’ tom. ii. 1837, p. 50.

  [417] Fritz Müller, ‘Facts and Arguments for Darwin,’ 1869, p.

  [418] ‘Travels in the Interior of Brazil,’ 1846, p. 111. I have
  given, in my ‘Journal of Researches,’ p. 463, an account of the
  habits of the Birgos.

  [419] Mr. Ch. Fraser, in ‘Proc. Zoolog. Soc.’ 1869, p. 3. I am
  indebted to Mr. Bate for the statement from Dr. Power.

  [420] Claus, ‘Die freilebenden Copepoden,’ 1863, s. 35.

  [421] ‘Facts and Arguments,’ &c., p. 79.

  [422] ‘A History of the Spiders of Great Britain,’ 1861-64. For
  the following facts, see p. 102, 77, 88.

  [423] Aug. Vinson (‘Aranéides des Iles de la Réunion,’ pl. vi.
  figs. 1 and 2) gives a good instance of the small size of the
  male in _Epeira nigra_. In this species, as I may add, the male
  is testaceous and the female black with legs banded with red.
  Other even more striking cases of inequality in size between
  the sexes have been recorded (‘Quarterly Journal of Science,’
  1868, July, p. 429); but I have not seen the original accounts.

  [424] Kirby and Spence, ‘Introduction to Entomology,’ vol. i.
  1818, p. 280.

  [425] Theridion (Asagena, Sund.) serratipes, 4-punctatum et
  guttatum; see Westring, in Kroyer, ‘Naturhist. Tidskrift,’ vol.
  iv. 1842-1843, p. 349; and vol. ii. 1846-1849, p. 342. See,
  also, for other species, ‘Araneæ Svecicæ,’ p. 184.

  [426] Walckenaer et P. Gervais, ‘Hist. Nat. des Insectes:
  Aptères,’ tom. iv. 1847, p. 17, 19, 68.

  [427] Sir J. Lubbock, ‘Transact. Linnean Soc.’ vol. xxv. 1866,
  p. 484. With respect to the Mutillidæ see Westwood, ‘Modern
  Class. of Insects,’ vol. ii. p. 213.

  [428] These organs in the male often differ in closely-allied
  species, and afford excellent specific characters. But their
  importance, under a functional point of view, as Mr. E.
  MacLachlan has remarked to me, has probably been overrated. It
  has been suggested, that slight differences in these organs
  would suffice to prevent the intercrossing of well-marked
  varieties or incipient species, and would thus aid in their
  development. That this can hardly be the case, we may infer
  from the many recorded cases (see for instance, Bronn,
  ‘Geschichte der Natur,’ B. ii. 1843, s. 164; and Westwood,
  ‘Transact. Ent. Soc.’ vol. iii. 1842, p. 195) of distinct
  species having been observed in union. Mr. MacLachlan informs
  me (vide ‘Stett. Ent. Zeitung,’ 1867, s. 155) that when several
  species of Phryganidæ, which present strongly-pronounced
  differences of this kind, were confined together by Dr. Aug.
  Meyer, _they coupled_, and one pair produced fertile ova.

  [429] ‘The Practical Entomologist,’ Philadelphia, vol. ii. May,
  1867, p. 88.

  [430] Mr. Walsh, ibid. p. 107.

  [431] ‘Modern Classification of Insects,’ vol. ii. 1840, p.
  206, 205. Mr. Walsh, who called my attention to this double use
  of the jaws, says that he has repeatedly observed this fact.

  [432] We have here a curious and inexplicable case of
  dimorphism, for some of the females of four European species of
  Dytiscus, and of certain species of Hydroporus, have their
  elytra smooth; and no intermediate gradations between sulcated
  or punctured and quite smooth elytra have been observed. See
  Dr. H. Schaum, as quoted in the ‘Zoologist,’ vol. v.-vi.
  1847-48, p. 1896. Also Kirby and Spence, ‘Introduction to
  Entomology,’ vol. iii. 1826, p. 305.

  [433] Westwood, ‘Modern Class.’ vol. ii. p. 193. The following
  statement about Penthe, and others in inverted commas, are
  taken from Mr. Walsh, ‘Practical Entomologist,’ Philadelphia,
  vol. ii. p. 88.

  [434] Kirby and Spence, ‘Introduct.’ &c., vol. iii. p. 332-336.

  [435] ‘Insecta Maderensia,’ 1854, p. 20.

  [436] E. Doubleday, ‘Annals and Mag. of Nat. Hist.’ vol. i.
  1848, p. 379. I may add that the wings in certain Hymenoptera
  (see Shuckard, ‘Fossorial Hymenop.’ 1837, p. 39-43) differ in
  neuration according to sex.

  [437] H. W. Bates, in ‘Journal of Proc. Linn. Soc.’ vol. vi.
  1862, p. 74. Mr. Wonfor’s observations are quoted in ‘Popular
  Science Review,’ 1868, p. 343.

  [438] Kirby and Spence, ‘Introduction to Entomology,’ vol. iii.
  p. 299.

  [439] Robinet, ‘Vers à Soie,’ 1848, p. 207.

  [440] ‘Transact. Ent. Soc.’ 3rd series, vol. v. p. 486.

  [441] ‘Journal of Proc. Ent. Soc.’ Feb. 4th, 1867, p. lxxi.

  [442] For this and other statements on the size of the sexes,
  see Kirby and Spence, ibid. vol. iii. p. 300; on the duration
  of life in insects, see p. 344.

  [443] ‘Transact. Linnean Soc.’ vol. xxvi. 1868, p. 296.

  [444] ‘The Malay Archipelago,’ vol. ii. 1869, p. 313.

  [445] ‘Modern Classification of Insects,’ vol. ii. 1840, p.

  [446] See Mr. B. T. Lowne’s very interesting work, ‘On the
  Anatomy of the Blow-Fly, Musca vomitoria,’ 1870, p. 14.

  [447] Westwood, ‘Modern Class. of Insects,’ vol. ii. p. 473.

  [448] These particulars are taken from Westwood’s ‘Modern
  Class. of Insects,’ vol. ii. 1840, p. 422. See, also, on the
  Fulgoridæ, Kirby and Spence, ‘Introduct.’ vol. ii. p. 401.

  [449] ‘Zeitschrift für wissenschaft. Zoolog.’ B. xvii. 1867, s.

  [450] I am indebted to Mr. Walsh for having sent me this
  extract from a ‘Journal of the Doings of Cicada septemdecim,’
  by Dr. Hartman.

  [451] L. Guilding, ‘Transact. Linn. Soc.’ vol. xv. p. 154.

  [452] Köppen, as quoted in the ‘Zoological Record,’ for 1867,
  p. 460.

  [453] Gilbert White, ‘Nat. Hist. of Selborne,’ vol. ii. 1825,
  p. 262.

  [454] Harris, ‘Insects of New England,’ 1842, p. 128.

  [455] ‘The Naturalist on the Amazons,’ vol. i. 1863, p. 252.
  Mr. Bates gives a very interesting discussion on the gradations
  in the musical apparatus of the three families. See also
  Westwood, ‘Modern Class.’ vol. ii. p. 445 and 453.

  [456] ‘Proc. Boston Soc. of Nat. Hist.’ vol. xi. April, 1868.

  [457] ‘Nouveau Manuel d’Anat. Comp.’ (French translat.), tom.
  i. 1850 p. 567.

  [458] ‘Zeitschrift für wissenschaft. Zoolog.’ B. xvii. 1867, s.

  [459] Westwood, ‘Modern Class. of Insects,’ vol. i. p. 440.

  [460] Westwood, ‘Modern Class. of Insects,’ vol. i. p. 453.

  [461] Landois, ibid. s. 121, 122.

  [462] Mr. Walsh also informs me that he has noticed that the
  female of the _Platyphyllum concavum_, “when captured makes a
  feeble grating noise by shuffling her wing-covers together.”

  [463] Landois, ibid. s. 113.

  [464] ‘Insects of New England,’ 1842, p. 133.

  [465] Westwood, ‘Modern Classification,’ vol. i. p. 462.

  [466] Westwood, ibid. vol. i. p. 453.

  [467] Landois, ibid. s. 115, 116, 120, 122.

  [468] ‘Transact. Ent. Soc.’ 3rd series, vol. ii. (‘Journal of
  Proceedings, p. 117.)

  [469] Westwood, ‘Modern Class. of Insects,’ vol. i. p. 427; for
  crickets, p. 445.

  [470] Mr. Ch. Horne, in ‘Proc. Ent. Soc.’ May 3, 1869, p. xii.

  [471] The _Oecanthus nivalis_, Harris, ‘Insects of New
  England,’ 1842, p. 124.

  [472] Platyblemnus: Westwood, ‘Modern. Class.’ vol. i. p. 447.

  [473] B. D. Walsh, the Pseudo-neuroptera of Illinois, in ‘Proc.
  Ent. Soc. of Philadelphia,’ 1862, p. 361.

  [474] ‘Modern Class.’ vol. ii. p. 37.

  [475] Walsh, ibid. p. 381. I am indebted to this naturalist for
  the following facts on Hetærina, Anax, and Gomphus.

  [476] ‘Transact. Ent. Soc’ vol. i. 1836, p. lxxxi.

  [477] See abstract in the ‘Zoological Record’ for 1867, p. 450.

  [478] Kirby and Spence, ‘Introduct. to Entomology,’ vol. ii.
  1818, p. 35.

  [479] See an interesting article, “The Writings of Fabre,” in
  ‘Nat. Hist. Review,’ April, 1862, p. 122.

  [480] ‘Journal of Proc. of Entomolog. Soc.’ Sept. 7th, 1863,
  p. 169.

  [481] P. Huber, ‘Recherches sur les Mœurs des Fourmis,’ 1810,
  p. 150, 165.

  [482] ‘Proc. Entomolog. Soc. of Philadelphia,’ 1866, p.

  [483] Quoted by Westwood, ‘Modern Class. of Insects,’ vol. ii.
  p. 214.

  [484] Pyrodes pulcherrimus, in which the sexes differ
  conspicuously, has been described by Mr. Bates in ‘Transact.
  Ent. Soc.’ 1869, p. 50. I will specify the few other cases in
  which I have heard of a difference in colour between the sexes
  of beetles. Kirby and Spence (‘Introduct. to Entomology,’ vol.
  iii. p. 301) mention a Cantharis, Meloe, Rhagium, and the
  _Leptura testacea_; the male of the latter being testaceous,
  with a black thorax, and the female of a dull red all over.
  These two latter beetles belong to the Order of Longicorns.
  Messrs. R. Trimen and Waterhouse, junr., inform me of two
  Lamellicorns, viz., a Peritrichia and Trichius, the male of the
  latter being more obscurely coloured than the female. In
  _Tillus elongatus_ the male is black, and the female always, as
  it is believed, of a dark blue colour with a red thorax. The
  male, also, of _Orsodacna atra_, as I hear from Mr. Walsh, is
  black, the female (the so-called _O. ruficollis_) having a
  rufous thorax.

  [485] ‘Proc. Entomolog. Soc. of Philadelphia,’ 1864, p. 228.

  [486] Kirby and Spence, ‘Introduct. Entomolog.’ vol. iii. p.

  [487] Kirby and Spence, ibid. vol. iii. p. 329.

  [488] ‘Modern Classification of Insects,’ vol. i. p. 172. On
  the same page there is an account of Siagonium. In the British
  Museum I noticed one male specimen of Siagonium in an
  intermediate condition, so that the dimorphism is not strict.

  [489] ‘The Malay Archipelago,’ vol. ii. 1869, p. 276.

  [490] ‘Entomological Magazine,’ vol. i. 1833, p. 82. See also
  on the conflicts of this species, Kirby and Spence, ibid. vol.
  iii. p. 314; and Westwood, ibid. vol. i. p. 187.

  [491] Quoted from Fischer, in ‘Dict. Class. d’Hist. Nat.’ tom.
  x. p. 324.

  [492] ‘Ann. Soc. Entomolog. France,’ 1866, as quoted in
  ‘Journal of Travel,’ by A. Murray, 1868, p. 135.

  [493] Westwood, ‘Modern Class.’ vol. i. p. 184.

  [494] Wollaston, On certain musical Curculionidæ, ‘Annals and
  Mag. of Nat. Hist.’ vol. vi. 1860, p. 14.

  [495] ‘Zeitschrift für wiss. Zoolog.’ B. xvii. 1867, s. 127.

  [496] I am greatly indebted to Mr. G. R. Crotch for having sent
  me numerous prepared specimens of various beetles belonging to
  these three families and others, as well as for valuable
  information of all kinds. He believes that the power of
  stridulation in the Clythra has not been previously observed. I
  am also much indebted to Mr. E. W. Janson, for information and
  specimens. I may add that my son, Mr. F. Darwin, finds that
  _Dermestes murinus_ stridulates, but he searched in vain for
  the apparatus. Scolytus has lately been described by Mr. Algen
  as a stridulator, in the ‘Edinburgh Monthly Magazine,’ 1869,
  Nov., p. 130.

  [497] Schiödte, translated in ‘Annals and Mag. of Nat. Hist.’
  vol. xx. 1867, p. 37.

  [498] Westring has described (Kroyer, ‘Naturhist. Tidskrift,’
  B. ii. 1848-49, p. 334) the stridulating organs in these two,
  as well as in other families. In the Carabidæ I have examined
  _Elaphrus uliginosus_ and _Blethisa multipunctata_, sent to me
  by Mr. Crotch. In Blethisa the transverse ridges on the
  furrowed border of the abdominal segment do not come into play,
  as far as I could judge, in scraping the rasps on the elytra.

  [499] I am indebted to Mr. Walsh, of Illinois, for having sent
  me extracts from Leconte’s ‘Introduction to Entomology,’ p.
  101, 143.

  [500] M. P. de la Brulerie, as quoted in ‘Journal of Travel,’
  A. Murray, vol. i. 1868, p. 135.

  [501] Mr. Doubleday informs me that “the noise is produced by
  the insect raising itself on its legs as high as it can, and
  then sinking its thorax five or six times, in rapid succession,
  against the substance upon which it is sitting.” For references
  on this subject see Landois, ‘Zeitschrift für wissen. Zoolog.’
  B. xvii. s. 131. Olivier says (as quoted by Kirby and Spence,
  ‘Introduct.’ vol. ii. p. 395) that the female of _Pimelia
  striata_ produces a rather loud sound by striking her abdomen
  against any hard substance, “and that the male, obedient to
  this call, soon attends her and they pair.”

  [502] Apatura Iris: ‘The Entomologist’s Weekly Intelligencer,’
  1859, p. 139. For the Bornean Butterflies see C. Collingwood,
  ‘Rambles of a Naturalist,’ 1868, p. 183.

  [503] See my ‘Journal of Researches,’ 1845, p. 33. Mr.
  Doubleday has detected (‘Proc. Ent. Soc.’ March 3rd, 1845, p.
  123) a peculiar membranous sac at the base of the front wings,
  which is probably connected with the production of the sound.

  [504] See also Mr. Bates’ paper in ‘Proc. Ent. Soc. of
  Philadelphia,’ 1865, p. 206. Also Mr. Wallace on the same
  subject, in regard to Diadema, in ‘Transact. Entomolog. Soc. of
  London,’ 1869, p. 278.

  [505] ‘The Naturalist on the Amazons,’ vol. i. 1863, p. 19.

  [506] See the interesting article in the ‘Westminster Review,’
  July, 1867, p. 10. A woodcut of the Kallima is given by Mr.
  Wallace in Hardwicke’s ‘Science Gossip,’ Sept. 1867, p. 196.

  [507] See the interesting observations by Mr. T. W. Wood, ‘The
  Student,’ Sept. 1868, p. 81.

  [508] Mr. Wallace in ‘Hardwicke’s Science Gossip,’ Sept. 1867,
  p. 193.

  [509] See also, on this subject, Mr. Weir’s paper in ‘Transact.
  Ent. Soc.’ 1869, p. 23.

  [510] ‘Westminster Review,’ July, 1867, p. 16.

  [511] For instance, Lithosia; but Prof. Westwood (‘Modern
  Class. of Insects,’ vol. ii. p. 390) seems surprised at this
  case. On the relative colours of diurnal and nocturnal
  Lepidoptera, see ibid. p. 333 and 392; also Harris, ‘Treatise
  on the Insects of New England,’ 1842, p. 315.

  [512] Such differences between the upper and lower surfaces of
  the wings of several species of Papilio, may be seen in the
  beautiful plates to Mr. Wallace’s Memoir on the Papilionidæ of
  the Malayan Region, in ‘Transact. Linn. Soc.’ vol. xxv. part i.

  [513] ‘Proc. Ent. Soc.’ March 2nd, 1868.

  [514] See also an account of the S. American genus Erateina
  (one of the Geometræ) in ‘Transact. Ent. Soc.’ new series, vol.
  v. pl. xv. and xvi.

  [515] ‘Proc. Ent. Soc. of London,’ July 6, 1868, p. xxvii.

  [516] Harris, ‘Treatise,’ &c., edited by Flint, 1862, p. 395.

  [517] For instance, I observe in my son’s cabinet that the
  males are darker than the females in the _Lasiocampa quercus_,
  _Odonestis potatoria_, _Hypogymna dispar_, _Dasychira
  pudibunda_, and _Cycnia mendica_. In this latter species the
  difference in colour between the two sexes is strongly marked;
  and Mr. Wallace informs me that we here have, as he believes,
  an instance of protective mimickry confined to one sex, as will
  hereafter be more fully explained. The white female of the
  Cycnia resembles the very common _Spilosoma menthrasti_, both
  sexes of which are white; and Mr. Stainton observed that this
  latter moth was rejected with utter disgust by a whole brood of
  young turkeys, which were fond of eating other moths; so that
  if the Cycnia was commonly mistaken by British birds for the
  Spilosoma, it would escape being devoured, and its white
  deceptive colour would thus be highly beneficial.

  [518] ‘Rambles of a Naturalist in the Chinese Seas,’ 1868, p.

  [519] Wallace on the Papilionidæ of the Malayan Region, in
  ‘Transact. Linn. Soc.’ vol. xxv. 1865, p. 8, 36. A striking case
  of a rare variety, strictly intermediate between two other
  well-marked female varieties, is given by Mr. Wallace. See also
  Mr. Bates, in ‘Proc. Entomolog. Soc.’ Nov. 19th, 1866, p. xl.

  [520] Mr. R. MacLachlan, ‘Transact. Ent. Soc.’ vol. ii. part
  6th, 3rd series, 1866, p. 459.

  [521] H. W. Bates, ‘The Naturalist on the Amazons,’ vol. ii.
  1863, p. 228. A. R. Wallace, in ‘Transact. Linn. Soc.’ vol. xxv.
  1865, p. 10.

  [522] On this whole subject see ‘The Variation of Animals and
  Plants under Domestication,’ vol. ii. 1868, chap. xxiii.

  [523] A. R. Wallace, in ‘The Journal of Travel,’ vol. i. 1868,
  p. 88. ‘Westminster Review,’ July, 1857, p. 37. See also
  Messrs. Wallace and Bates in ‘Proc. Ent. Soc.’ Nov. 19th, 1866,
  p. xxxix.

  [524] ‘The Variation of Animals and Plants under
  Domestication,’ vol. ii. chap. xii. p. 17.

  [525] ‘Transact. Linn. Soc.’ vol. xxiii. 1862, p. 495.

  [526] ‘Proc. Ent. Soc.’ Dec. 3rd, 1866, p. xlv.

  [527] ‘Transact. Linn. Soc.’ vol. xxv. 1865, p. 1; also
  ‘Transact. Ent. Soc.’ vol. iv. (3rd series), 1867, p. 301.

  [528] See an ingenious article entitled, “Difficulties of the
  Theory of Natural Selection,” in the ‘Month,’ 1869. The writer
  strangely supposes that I attribute the variations in colour of
  the Lepidoptera, by which certain species belonging to distinct
  families have come to resemble others, to reversion to a common
  progenitor; but there is no more reason to attribute these
  variations to reversion than in the case of any ordinary

  [529] Wallace, “Notes on Eastern Butterflies,” ‘Transact. Ent.
  Soc.’ 1869, p. 287.

  [530] Wallace, in ‘Westminster Review,’ July, 1867, p. 37; and
  in ‘Journal of Travel and Nat. Hist.’ vol. i. 1868, p. 88.

  [531] See remarks by Messrs. Bates and Wallace, in ‘Proc. Ent.
  Soc.’ Nov. 19, 1866, p. xxxix.

  [532] See Mr. Wallace in ‘Westminster Review,’ July, 1867, p.
  11 and 37. The male of no butterfly, as Mr. Wallace informs me,
  is known to differ in colour, as a protection, from the female;
  and he asks me how I can explain this fact on the principle
  that one sex alone has varied and has transmitted its
  variations exclusively to the same sex, without the aid of
  selection to check the variations being inherited by the other
  sex. No doubt if it could be shewn that the females of very
  many species had been rendered beautiful through protective
  mimickry, but that this has never occurred with the males, it
  would be a serious difficulty. But the number of cases as yet
  known hardly suffices for a fair judgment. We can see that the
  males, from having the power of flying more swiftly, and thus
  escaping danger, would not be so likely as the females to have
  had their colours modified for the sake of protection; but this
  would not in the least have interfered with their receiving
  protective colours through inheritance from the females. In the
  second place, it is probable that sexual selection would
  actually tend to prevent a beautiful male from becoming
  obscure, for the less brilliant individuals would be less
  attractive to the females. Supposing that the beauty of the
  male of any species had been mainly acquired through sexual
  selection, yet if this beauty likewise served as a protection,
  the acquisition would have been aided by natural selection. But
  it would be quite beyond our power to distinguish between the
  two processes of sexual and ordinary selection. Hence it is not
  likely that we should be able to adduce cases of the males
  having been rendered brilliant exclusively through protective
  mimickry, though this is comparatively easy with the females,
  which have rarely or never been rendered beautiful, as far as
  we can judge, for the sake of sexual attraction, although they
  have often received beauty through inheritance from their male

  [533] ‘Proc. Entomolog. Soc.’ Dec. 3rd, 1866, p. xlv., and
  March 4th, 1867, p. lxxx.

  [534] See Mr. J. Jenner Weir’s paper on insects and
  insectivorous birds, in ‘Transact. Ent. Soc.’ 1869, p. 21; also
  Mr. Butler’s paper, ibid. p. 27.




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Footnote 292 spells the city Charleston but the text has it as
Charlestown. This is as in the original book.

Inconsistent spelling of St. Petersburg/Petersburgh as in the original

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