| By Author | [ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | Other Symbols ] |
| By Title | [ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | Other Symbols ] |
| By Language |
|
Download this book: [ ASCII ] Look for this book on Amazon Tweet |
Title: Darwinism stated by Darwin himself: Characteristic passages from the writings of Charles Darwin
Author: Darwin, Charles
Language: English
As this book started as an ASCII text book there are no pictures available.
*** Start of this LibraryBlog Digital Book "Darwinism stated by Darwin himself: Characteristic passages from the writings of Charles Darwin" ***
HIMSELF ***
Transcriber’s Note: Sidenotes are shown enclosed in square brackets,
above the paragraphs to which they apply. Italic text is enclosed in
_underscores_.
DARWINISM
STATED BY DARWIN HIMSELF.
_CHARACTERISTIC PASSAGES
FROM THE WRITINGS OF CHARLES DARWIN._
SELECTED AND ARRANGED
BY
NATHAN SHEPPARD,
AUTHOR OF
“SHUT UP IN PARIS,” EDITOR OF “THE DICKENS READER,” “CHARACTER
READINGS FROM GEORGE ELIOT,” AND “GEORGE ELIOT’S ESSAYS.”
“There is grandeur in this view of life, with its several powers,
having been originally breathed by the Creator into a few forms or
into one; and that, while this planet has gone cycling on according
to the fixed law of gravity, from so simple a beginning endless
forms most beautiful and most wonderful have been and are being
evolved.”--_The Origin of Species_, page 429.
NEW YORK:
D. APPLETON AND COMPANY,
1, 3, AND 5 BOND STREET.
1884.
COPYRIGHT, 1884,
BY D. APPLETON AND COMPANY.
PREFACE.
While these selections can not but be useful to those who are perfectly
familiar with the writings of Darwin, they are designed especially
for those who know little, or nothing, about his line of research and
argument, and yet would like to obtain a general idea of it in a form
which shall be at once authentic, brief, and inexpensive.
This volume contains, of course, only an outline of the contents of
the twelve volumes from which it is compiled, and for which it is by
no means intended as a substitute. It will, on the contrary, we should
hope, create an appetite which can be satisfied only by a careful
reading of the works themselves.
Darwin’s repetitions, necessitated by his method of investigation
and publication, and his unexampled candor in controversy, have been
something of an embarrassment in the classification of these passages;
so that we have been obliged in some instances to sacrifice continuity
to perspicuity. But, as one object of this book is to correct
misrepresentations by giving Darwin’s views in his own language, some
of his own repetitions must be given also, in order to leave no doubt
as to precisely what he said and did not say. It will probably be a
long while before the dispute over the theory that he advocated will
cease, but there is certainly no excuse for a difference of opinion
with regard to the language that he used, and the meaning he attached
to it. That language and that meaning will be found in these pages.
Darwinism stated by its opponents is one thing, Darwinism stated by
Darwin himself will be found to be quite another thing, for, to use his
own exclamation, “great is the power of steady misrepresentation!”
The order followed in the arrangement of these extracts is not that
of the books, but the one naturally suggested by our plan, which is
designed to conduct the reader through the vegetable up to the animal
kingdom, and up from the lowest to the highest animal, man, “the wonder
and glory of the universe.”
The references are to the American edition of Darwin’s works published
by D. Appleton & Co., New York.
It is no part of our purpose to discuss the theory expounded here, but
we can not refrain from joining in the general expression of admiration
for its illustrious expounder. Lord Derby says, “He was one of half
a dozen men of this century who will be remembered a century hence”;
and yet his friends were “more impressed with the dignified simplicity
of his nature than by the great work he had done.” Professor Huxley
compares him to Socrates in wisdom and humility; and there could be no
better authority than Mr. A. R. Wallace for the statement that “there
are none to stand beside him as equals in the whole domain of science.”
He has been extolled, since his death, by a host of religious leaders
in press and pulpit (some of whose utterances will be found on another
page), and we concur with them in the opinion that science never had a
champion whose temper and behavior were more nearly in accord with the
practical injunctions of the Christian religion. Whatever we or any one
may think of Darwin’s scientific theories, no one can gainsay the value
of his personal example, and few can be so prejudiced as to resist the
fascination that will always be felt at the mention of his name.
NEW YORK, _February 1, 1884_.
INTRODUCTORY PASSAGES QUOTED BY DARWIN IN HIS “ORIGIN OF SPECIES.”
“But with regard to the material world, we can at least go so far as
this--we can perceive that events are brought about not by insulated
interpositions of divine power, exerted in each particular case, but by
the establishment of general laws.”--WHEWELL: _Bridgewater Treatise_.
“The only distinct meaning of the word ‘natural’ is _stated_, _fixed_,
or _settled_; since what is natural as much requires and presupposes an
intelligent agent to render it so, i. e., to effect it continually or
at stated times, as what is supernatural or miraculous does to effect
it for once.”--BUTLER: _Analogy of Revealed Religion_.
“To conclude, therefore, let no man out of a weak conceit of sobriety,
or an ill-applied moderation, think or maintain, that a man can
search too far or be too well studied in the book of God’s word, or
in the book of God’s works; divinity or philosophy; but rather let
men endeavor an endless progress or proficience in both.”--BACON:
_Advancement of Learning_.
DARWIN AND HIS THEORIES FROM A RELIGIOUS POINT OF VIEW.
“Surely in such a man lived that true charity which is the very essence
of the true spirit of Christ.”--Canon PROTHERO.
“The moral lesson of his life is perhaps even more valuable than is the
grand discovery which he has stamped on the world’s history.”--_The
Observer_ (London).
“Darwin’s writings may be searched in vain for an irreverent or
unbelieving word.”--_The Church Review._
“The doctrine of evolution with which Darwin’s name would always be
associated lent itself at least as readily to the old promise of God as
to more modern but less complete explanations of the universe.”--Canon
BARRY.
“The fundamental doctrine of the theist is left precisely as it was.
The belief in the great Creator and Ruler of the Universe is, as we
have seen, confessed by the author of these doctrines. The grounds
remain untouched of faith in the personal Deity who is in intimate
relation with individual souls, who is their guide and helper in life,
and who can be trusted in regard to the great hereafter.”--_The Church
Quarterly Review._
“It appears impossible to overrate the gain we have won in the
stupendous majesty of this (Darwin’s) idea of the Creator and
creation.”--_Sunday-School Chronicle._
“It is certain that Mr. Darwin’s books contain a marvelous store of
patiently accumulated and most interesting facts. Those facts seem
to point in the direction of the belief that the Great Spirit of
the Universe has wrought slowly and with infinite patience, through
innumerable ages, rather than by abrupt intervention and by means of
great catastrophes, in the production of the results, in the animate
and inanimate world, which now offer to the student of nature boundless
scope for observation and inquiry.”--_The Christian World._
“Let us see, in the funeral honors paid within these holy precincts to
our greatest naturalist, a happy trophy of the reconciliation between
faith and science.”--_The Guardian._
“That there is some truth in the theory of evolution, however, most
scientists, including those of Christian faith, believe, and Mr. Darwin
certainly has done much to make the facts plain; but no scientific
principle established by him ever has undermined any truth of the
Gospel.”--_The Congregationalist._
“Christian believers are found among the ranks of evolutionists
without apparent prejudice to their faith. Professor Mivart, the
zoölogist; Professor Asa Gray, the botanist; Professor Le Conte and
Professor Winchell, the geologists, may be named as among these.”--_The
Presbyterian._
“In all his simple and noble life Mr. Darwin was influenced by the
profoundly religious conviction that nothing was beneath the earnest
study of man which had been worthy of the mighty hand of God.”--Canon
FARRAR.
“He has not one word to say against religion; ... by-and-by it may be
seen that he has done much to put religious faith as well as scientific
knowledge on a higher plane.”--_Independent._
“A celebrated author and divine has written to me that ‘he has
gradually learned to see that it is just as noble a conception of
the Deity to believe that he created a few original forms capable of
self-development into other and needful forms, as to believe that he
required a fresh act of creation to supply the voids caused by the
action of his laws.’”--_Origin of Species_, page 422.
“I am at the head of a college where to declare against it [evolution]
would perplex my best students. They would ask me which to give up,
science or the Bible.... It is but the evolution of Genesis when each
‘brings forth after its kind.’ Science tells the same story. But what
is the limit of the fixedness of the law? I believe that the evolution
of new species is a question in science, and not of religion. It should
be left to scientific men.”--President MCCOSH.
CONTENTS.
I.
PAGE
THE MOVEMENTS AND HABITS OF PLANTS.
The Movement of Plants in Relation to their Wants 2
The Power of Movement in Animal and Plant compared 4
Advantages of Cross-Fertilization 6
Potency of the Sexual Elements in Plants 6
Experiments in Crossing 8
The Struggle for Existence among Seeds 9
Practical Application of these Views 9
Marriages of First Cousins 11
Development of the Two Sexes in Plants 12
Why the Sexes have been reseparated 14
Comparative Fertility of Male and Female Plants 15
Effect of Climate on Reproduction 16
Causes of Sterility among Plants 17
An “Ideal Type” or Inevitable Modification 18
Special Adaptations to a Changing Purpose 19
An Illustration 21
As interesting on the Theory of Development as on that of Direct
Interposition 22
The Sleep of the Plants 24
Self-Protection during Sleep 25
Influence of Light upon Plants 28
Influence of Gravitation upon Plants 29
The Power of Digestion in Plants 31
Diverse Means by which Plants gain their Subsistence 34
How a Plant preys upon Animals 35
II.
THE PART PLAYED BY WORMS IN THE HISTORY OF THIS PLANET.
They preserve Valuable Ruins 42
They prepare the Ground for Seed 43
Intelligence of Worms 45
III.
THE LAWS OF VARIABILITY WITH RESPECT TO ANIMALS AND PLANTS.
Inherited Effect of Changed Habits 48
Effects of the Use and Disuse of Parts 50
Vague Origin of our Domestic Animals 52
Descent of the Domestic Pigeon 53
Origin of the Dog 55
Origin of the Horse 57
Causes of Modifications in the Horse 58
“Making the Works of God a mere Mockery” 59
Variability of Cultivated Plants 61
Savage Wisdom in the Cultivation of Plants 62
Unknown Laws of Inheritance 64
Laws of Inheritance that are fairly well established 66
Inherited Peculiarities in Man 67
Inherited Diseases 68
Causes of Non-Inheritance 69
Steps by which Domestic Races have been produced 71
Unconscious Selection 73
Adaptation of Animals to the Fancies of Man 74
Doubtful Species 75
Species an Arbitrary Term 77
The True Plan of Creation 79
IV.
THE STRUGGLE FOR EXISTENCE.
Death inevitable in the Fight for Life 82
“Inexplicable on the Theory of Creation” 84
Obscure Checks to Increase 85
Climate as a Check to Increase 86
Influence of Insects in the Struggle for Existence 88
No such Thing as Change in the Result of the Struggle 90
V.
NATURAL SELECTION; OR, THE SURVIVAL OF THE FITTEST.
An Invented Hypothesis 93
How far the Theory may be extended 94
Is there any Limit to what Selection can effect? 96
Has Organization advanced? 97
A Higher Workmanship than Man’s 99
Why Habits and Structure are not in Agreement 102
No Modification in one Species designed for the Good of Another 103
Illustrations of the Action of Natural Selection 106
Divergence of Character 108
Evolution of the Human Eye 110
VI.
GEOGRAPHICAL DISTRIBUTION OF ORGANIC BEINGS.
Isolated Continents never were united 115
Means of Dispersal 116
These Means of Transport not accidental 118
Dispersal during the Glacial Period 119
The Theory of Creation inadequate 122
Causes of a Glacial Climate 123
Difficulties not yet removed 124
Identity of the Species of Islands with those of the Mainland
explained only by this Theory 125
VII.
EVIDENCE OF THE DESCENT OF MAN FROM SOME LOWER FORM.
Points of Correspondence between Man and the other Animals 129
The facts of Embryology and the Theory of Development 131
Two Principles that explain the Facts 134
Embryology against Abrupt Changes 135
Rudimentary Organs only to be explained on the Theory of
Development 137
“No other Explanation has ever been given” 139
Unity of Type explained by Relationship 140
Inexplicable on the Ordinary View of Creation 142
Descent with Modification the only Explanation 143
The History of Life on the Theory of Descent with Modification 144
Letters retained in the Spelling but Useless in Pronunciation 146
Man’s Deficiency in Tail 147
Points of Resemblance between Man and Monkey 149
Variability of Man 152
Causes of Variability in Domesticated Man 153
Action of Changed Conditions 155
The Inherited Effects of the Increased and Diminished Use of
Parts 156
Reversion as a Factor in the Development of Man 158
Reversion in the Human Family 160
Prepotence in the Transmission of Character 162
Natural Selection in the Development of Man 163
How Man became upright 165
The Brain enlarges as the Mental Faculties develop 167
Nakedness of the Skin 169
Is Man the most helpless of the Animals? 171
VIII.
MENTAL POWERS OF MAN AND THE LOWER ANIMALS COMPARED.
Fundamental Intuitions the same in Man and the other Animals 175
Man and the Lower Animals excited by the same Emotions 177
All Animals possess some Power of Reasoning 179
The Power of Association in Dog and Savage 181
The Lower Animals progress in Intelligence 182
The Power of Abstraction 183
The Evolution of Language 185
Development of Languages and Species compared 188
The Sense of Beauty 191
Development of the Ear for Music 192
IX.
DEVELOPMENT OF THE MORAL SENSE.
From the Social Instincts to the Moral Sense 195
Human Sympathy among Animals 197
The Love of Approbation 199
Fellow-Feeling for our Fellow-Animals 200
Development of the Golden Rule 201
Regret peculiar to Man, and why 202
Remorse explained 204
Development of Self-Control 205
Variability of Conscience 207
Progress not an Invariable Rule 209
All Civilized Nations are the Descendants of Barbarians 210
“The Ennobling Belief in God” 213
X.
THE GENEALOGY OF MAN.
Man a Sub-Order 218
The Birthplace of Man 221
Origin of the Vertebrata 224
From no Bone to Backbone 226
Does Mankind consist of Several Species? 228
The Races graduate into each other 229
Was the First Man a Speaking Animal? 231
The Theory of a Single Pair 231
Civilized out of Existence 233
XI.
SEXUAL SELECTION AS AN AGENCY TO ACCOUNT FOR THE DIFFERENCES
BETWEEN THE RACES OF MAN.
Struggle of the Males for the Possession of the Females 236
Courtship among the Lower Animals 237
Why the Male plays the more Active Part in Courting 239
Transmission of Sexual Characteristics 240
An Objection answered 242
Difference between the Sexes created by Sexual Selection 243
How Woman could be made to reach the Standard of Man 246
“Characteristic Selfishness of Man” 247
No Universal Standard of Beauty among Mankind 248
Development of the Beard 249
Development of the Marriage-Tie 250
Unnatural Selection in Marriage 252
Modifying Influences in Both Sexes 254
“Grounds that will never be shaken” 256
XII.
THE EXPRESSION OF THE EMOTIONS IN MAN AND OTHER ANIMALS.
The Principle of Associated Habit 258
The Principle of Antithesis 261
Origin of the Principle of Antithesis 263
The Principle of the Action of the Excited Nervous System on the
Body 265
XIII.
MEANS OF THE EXPRESSION OF THE EMOTIONS.
Vocal Organs 268
Erection of the Hair 269
Erection of the Ears 270
A Startled Horse 271
Monkey-Shines 271
Weeping of Man and Brute 272
The Grief-Muscles 275
Voluntary Power over the Grief-Muscles 276
“Down in the Mouth” 278
Laughter 279
Expression of the Devout Emotions 282
Frowning 284
Pouting 285
Decision at the Mouth 287
Anger 287
Sneering 288
Disgust 289
Shrugging the Shoulders 290
Blushing 291
Blushing not necessarily an Expression of Guilt 293
Blushing accounted for 294
A New Argument for a Single Parent-Stock 296
XIV.
THE PROVISIONAL HYPOTHESIS OF PANGENESIS.
Functional Independence of the Units of the Body 299
Necessary Assumptions 302
Two Objections answered 305
Effect of Morbid Action 306
Transmission limited 307
XV.
OBJECTIONS TO THE THEORY OF DESCENT WITH MODIFICATION CONSIDERED.
Misrepresentations corrected 310
Lapse of Time and Extent of Area 311
Why the Higher Forms have not supplanted the Lower 313
The Amount of Life must have a Limit 316
The Broken Branches of the Tree of Life 317
Why we do not find Transitional Forms 319
How could the Transitional Form have subsisted? 322
Why Nature takes no Sudden Leaps 323
Imperfect Contrivances of Nature accounted for 324
Instincts as a Difficulty 325
Some Instincts acquired and some lost 327
Innumerable Links necessarily lost 329
Plenty of Time for the Necessary Gradations 331
Wide Intervals of Time between the Geological Formations 334
Sudden Appearance of Groups of Allied Species 336
How little we know of Former Inhabitants of the World 337
The Extinction of Species involved in Mystery 338
Dead Links between Living Species 340
Living Descendants of Fossil Species 342
Unnecessary to explain the Cause of each Individual Difference 343
“Face to Face with an Insoluble Difficulty” 344
Why distasteful? 346
“Accords better with what we know of the Creator’s Laws” 347
The Grandeur of this View of Life 348
Not incompatible with the Belief in Immortality 349
DARWINISM
STATED BY DARWIN HIMSELF.
I.
THE MOVEMENTS AND HABITS OF PLANTS.
[The Power
of Movement
in Plants,
page 1.]
The most widely prevalent movement is essentially of the same nature
as that of the stem of a climbing plant, which bends successively to
all points of the compass, so that the tip revolves. This movement has
been called by Sachs “revolving nutation”; but we have found it much
more convenient to use the terms _circumnutation_ and _circumnutate_.
As we shall have to say much about this movement, it will be useful
here briefly to describe its nature. If we observe a circumnutating
stem, which happens at the time to be bent, we will say toward the
north, it will be found gradually to bend more and more easterly, until
it faces the east; and so onward to the south, then to the west, and
back again to the north. If the movement had been quite regular, the
apex would have described a circle, or rather, as the stem is always
growing upward, a circular spiral. But it generally describes irregular
elliptical or oval figures; for the apex, after pointing in any one
direction, commonly moves back to the opposite side, not, however,
returning along the same line. Afterward other irregular ellipses or
ovals are successively described, with their longer axes directed to
different points of the compass. While describing such figures, the
apex often travels in a zigzag line, or makes small subordinate loops
or triangles. In the case of leaves the ellipses are generally narrow.
[Page 3.]
Even the stems of seedlings before they have broken through the ground,
as well as their buried radicles, circumnutate, as far as the pressure
of the surrounding earth permits. In this universally present movement
we have the basis or groundwork for the acquirement, according to the
requirements of the plant, of the most diversified movements.
THE MOVEMENT OF PLANTS IN RELATION TO THEIR WANTS.
[The Movements
and Habits
of Climbing
Plants,
page 202.]
The most interesting point in the natural history of climbing plants
is the various kinds of movement which they display in manifest
relation to their wants. The most different organs--stems, branches,
flower-peduncles, petioles, mid-ribs of the leaf and leaflets, and
apparently aërial roots--all possess this power.
1. The first action of a tendril is to place itself in a proper
position. For instance, the tendril of _Cobæa_ first rises vertically
up, with its branches divergent and with the terminal hooks turned
outward; the young shoot at the extremity of the stem is at the same
time bent to one side, so as to be out of the way. The young leaves of
clematis, on the other hand, prepare for action by temporarily curving
themselves downward, so as to serve as grapnels.
2. If a twining plant or a tendril gets by any accident into an
inclined position, it soon bends upward, though secluded from the
light. The guiding stimulus no doubt is the attraction of gravity, as
Andrew Knight showed to be the case with germinating plants. If a shoot
of any ordinary plant be placed in an inclined position in a glass of
water in the dark, the extremity will, in a few hours, bend upward;
and, if the position of the shoot be then reversed, the downward-bent
shoot reverses its curvature; but if the stolon of a strawberry, which
has no tendency to grow upward, be thus treated, it will curve downward
in the direction of, instead of in opposition to, the force of gravity.
As with the strawberry, so it is generally with the twining shoots of
the _Hibbertia dentata_, which climbs laterally from bush to bush; for
these shoots, if placed in a position inclined downward, show little
and sometimes no tendency to curve upward.
3. Climbing plants, like other plants, bend toward the light by a
movement closely analogous to the incurvation which causes them to
revolve, so that their revolving movement is often accelerated or
retarded in traveling to or from the light. On the other hand, in a few
instances tendrils bend toward the dark.
4. We have the spontaneous revolving movement which is independent of
any outward stimulus, but is contingent on the youth of the part, and
on vigorous health; and this again, of course, depends on a proper
temperature and other favorable conditions of life.
5. Tendrils, whatever their homological nature may be, and the petioles
or tips of the leaves of leaf-climbers, and apparently certain roots,
all have the power of movement when touched, and bend quickly toward
the touched side. Extremely slight pressure often suffices. If the
pressure be not permanent, the part in question straightens itself and
is again ready to bend on being touched.
6. Tendrils, soon after clasping a support, but not after a mere
temporary curvature, contract spirally. If they have not come into
contact with any object, they ultimately contract spirally, after
ceasing to revolve; but in this case the movement is useless, and
occurs only after a considerable lapse of time.
With respect to the means by which these various movements are
effected, there can be little doubt, from the researches of Sachs and
H. de Vries, that they are due to unequal growth; but, from the reasons
already assigned, I can not believe that this explanation applies to
the rapid movements from a delicate touch.
Finally, climbing plants are sufficiently numerous to form a
conspicuous feature in the vegetable kingdom, more especially in
tropical forests. America, which so abounds with arboreal animals,
as Mr. Bates remarks, likewise abounds, according to Mohl and Palm,
with climbing plants; and, of the tendril-bearing plants examined by
me, the highest developed kinds are natives of this grand continent,
namely, the several species of _Bignonia_, _Eccremocarpus_, _Cobæa_,
and _Ampelopsis_. But even in the thickets of our temperate regions the
number of climbing species and individuals is considerable, as will be
found by counting them.
THE POWER OF MOVEMENT IN ANIMAL AND PLANT COMPARED.
[Page 206.]
It has often been vaguely asserted that plants are distinguished from
animals by not having the power of movement. It should rather be said
that plants acquire and display this power only when it is of some
advantage to them; this being of comparatively rare occurrence, as
they are affixed to the ground, and food is brought to them by the air
and rain. We see how high in the scale of organization a plant may
rise, when we look at one of the more perfect tendril-bearers. It
first places its tendrils ready for action, as a polypus places its
tentacula. If the tendril be displaced, it is acted on by the force
of gravity and rights itself. It is acted on by the light, and bends
toward or from it, or disregards it, whichever maybe most advantageous.
During several days the tendrils or internodes, or both, spontaneously
revolve with a steady motion. The tendril strikes some object, and
quickly curls round and firmly grasps it. In the course of some hours
it contracts into a spire, dragging up the stem, and forming an
excellent spring. All movements now cease. By growth the tissues soon
become wonderfully strong and durable. The tendril has done its work,
and has done it in an admirable manner.
* * * * *
[The Power
of Movement
in Plants,
page 571.]
It is impossible not to be struck with the resemblance between the
foregoing movements of plants and many of the actions performed
unconsciously by the lower animals. With plants an astonishingly
small stimulus suffices; and even with allied plants one may be
highly sensitive to the slightest continued pressure, and another
highly sensitive to a slight momentary touch. The habit of moving at
certain periods is inherited both by plants and animals; and several
other points of similitude have been specified. But the most striking
resemblance is the localization of their sensitiveness, and the
transmission of an influence from the excited part to another which
consequently moves. Yet plants do not, of course, possess nerves or
a central nervous system; and we may infer that with animals such
structures serve only for the more perfect transmission of impressions,
and for the more complete intercommunication of the several parts.
ADVANTAGES OF CROSS-FERTILIZATION.
[The Effects
of Cross
and Self
Fertilization
in the
Vegetable
Kingdom,
page 443.]
There are two important conclusions which may be deduced from my
observations: 1. That the advantages of cross-fertilization do not
follow from some mysterious virtue in the mere union of two distinct
individuals, but from such individuals having been subjected during
previous generations to different conditions, or to their having
varied in a manner commonly called spontaneous, so that in either case
their sexual elements have been in some degree differentiated; and, 2.
That the injury from self-fertilization follows from the want of such
differentiation in the sexual elements. These two propositions are
fully established by my experiments. Thus, when plants of the _Ipomœa_
and of the _Mimulus_, which had been self-fertilized for the seven
previous generations, and had been kept all the time under the same
conditions, were intercrossed one with another, the offspring did not
profit in the least by the cross.
* * * * *
[Page 451.]
The curious cases of plants which can fertilize and be fertilized by
any other individual of the same species, but are altogether sterile
with their own pollen, become intelligible, if the view here propounded
is correct, namely, that the individuals of the same species growing in
a state of nature near together have not really been subjected during
several previous generations to quite the same conditions.
POTENCY OF THE SEXUAL ELEMENTS IN PLANTS.
[Page 446.]
It is obvious that the exposure of two sets of plants during several
generations to different conditions can lead to no beneficial results,
as far as crossing is concerned, unless their sexual elements are
thus affected. That every organism is acted on to a certain extent by
a change in its environment will not, I presume, be disputed. It is
hardly necessary to advance evidence on this head; we can perceive the
difference between individual plants of the same species which have
grown in somewhat more shady or sunny, dry or damp places. Plants which
have been propagated for some generations under different climates or
at different seasons of the year transmit different constitutions to
their seedlings. Under such circumstances, the chemical constitution
of their fluids and the nature of their tissues are often modified.
Many other such facts could be adduced. In short, every alteration in
the function of a part is probably connected with some corresponding,
though often quite imperceptible, change in structure or composition.
Whatever affects an organism in any way, likewise tends to act on its
sexual elements. We see this in the inheritance of newly acquired
modifications, such as those from the increased use or disuse of
a part, and even from mutilations if followed by disease. We have
abundant evidence how susceptible the reproductive system is to changed
conditions, in the many instances of animals rendered sterile by
confinement; so that they will not unite, or, if they unite, do not
produce offspring, though the confinement may be far from close; and
of plants rendered sterile by cultivation. But hardly any cases afford
more striking evidence how powerfully a change in the conditions of
life acts on the sexual elements than those already given, of plants
which are completely self-sterile in one country, and, when brought
to another, yield, even in the first generation, a fair supply of
self-fertilized seeds.
But it may be said, granting that changed conditions act on the sexual
elements, How can two or more plants growing close together, either in
their native country or in a garden, be differently acted on, inasmuch
as they appear to be exposed to exactly the same conditions?
EXPERIMENTS IN CROSSING.
[Page 447.]
In my experiments with _Digitalis purpurea_, some flowers on a wild
plant were self-fertilized, and others were crossed with pollen from
another plant growing within two or three feet distance. The crossed
and self-fertilized plants raised from the seeds thus obtained
produced flower-stems in number as 100 to 47, and in average height
as 100 to 70. Therefore, the cross between these two plants was
highly beneficial; but how could their sexual elements have been
differentiated by exposure to different conditions? If the progenitors
of the two plants had lived on the same spot during the last score
of generations, and had never been crossed with any plant beyond the
distance of a few feet, in all probability their offspring would
have been reduced to the same state as some of the plants in my
experiments--such as the intercrossed plants of the ninth generation
of _Ipomœa_, or the self-fertilized plants of the eighth generation of
_Mimulus_, or the offspring from flowers on the same plant; and in this
case a cross between the two plants of _Digitalis_ would have done no
good. But seeds are often widely dispersed by natural means, and one
of the above two plants, or one of their ancestors, may have come from
a distance, from a more shady or sunny, dry or moist place, or from
a different kind of soil containing other organic seeds or inorganic
matter.
THE STRUGGLE FOR EXISTENCE AMONG SEEDS.
[Page 449.]
Seeds often lie dormant for several years in the ground, and germinate
when brought near the surface by any means, as by burrowing animals.
They would probably be affected by the mere circumstance of having
long lain dormant; for gardeners believe that the production of double
flowers, and of fruit, is thus influenced. Seeds, moreover, which were
matured during different seasons will have been subjected during the
whole course of their development to different degrees of heat and
moisture.
It has been shown that pollen is often carried by insects to a
considerable distance from plant to plant. Therefore, one of the
parents or ancestors of our two plants of _Digitalis_ may have been
crossed by a distant plant growing under somewhat different conditions.
Plants thus crossed often produce an unusually large number of seeds;
a striking instance of this fact is afforded by the _Bignonia_, which
was fertilized by Fritz Müller with pollen from some adjoining plants
and set hardly any seed, but, when fertilized with pollen from a
distant plant, was highly fertile. Seedlings from a cross of this kind
grow with great vigor, and transmit their vigor to their descendants.
These, therefore, in the struggle for life, will generally beat and
exterminate the seedlings from plants which have long grown near
together under the same conditions, and will thus tend to spread.
PRACTICAL APPLICATION OF THESE VIEWS.
[Page 458.]
Under a practical point of view, agriculturists and horticulturists
may learn something from the conclusions at which we have arrived.
Firstly, we see that the injury from the close breeding of animals
and from the self-fertilization of plants does not necessarily
depend on any tendency to disease or weakness of constitution common
to the related parents, and only indirectly on their relationship,
in so far as they are apt to resemble each other in all respects,
including their sexual nature. And, secondly, that the advantages
of cross-fertilization depend on the sexual elements of the parents
having become in some degree differentiated by the exposure of their
progenitors to different conditions, or from their having intercrossed
with individuals thus exposed; or, lastly, from what we call in
our ignorance spontaneous variation. He therefore who wishes to
pair closely related animals ought to keep them under conditions as
different as possible.
* * * * *
[Page 459.]
As some kinds of plants suffer much more from self-fertilization than
do others, so it probably is with animals from too close interbreeding.
The effects of close interbreeding on animals, judging again from
plants, would be deterioration in general vigor, including fertility,
with no necessary loss of excellence of form; and this seems to be the
usual result.
It is a common practice with horticulturists to obtain seeds from
another place having a very different soil, so as to avoid raising
plants for a long succession of generations under the same conditions;
but, with all the species which freely intercross by the aid of insects
or the wind, it would be an incomparably better plan to obtain seeds
of the required variety, which had been raised for some generations
under as different conditions as possible, and sow them in alternate
rows with seeds matured in the old garden. The two stocks would then
intercross, with a thorough blending of their whole organizations, and
with no loss of purity to the variety; and this would yield far more
favorable results than a mere exchange of seeds. We have seen in my
experiments how wonderfully the offspring profited in height, weight,
hardiness, and fertility, by crosses of this kind. For instance,
plants of _Ipomœa_ thus crossed were to the intercrossed plants of
the same stock, with which they grew in competition, as 100 to 78 in
height, and as 100 to 51 in fertility; and plants of _Eschscholtzia_
similarly compared were as 100 to 45 in fertility. In comparison
with self-fertilized plants the results are still more striking;
thus cabbages derived from a cross with a fresh stock were to the
self-fertilized as 100 to 22 in weight.
Florists may learn, from the four cases which have been fully
described, that they have the power of fixing each fleeting variety
of color, if they will fertilize the flowers of the desired kind with
their own pollen for half a dozen generations, and grow the seedlings
under the same conditions. But a cross with any other individual of the
same variety must be carefully prevented, as each has its own peculiar
constitution. After a dozen generations of self-fertilization, it is
probable that the new variety would remain constant even if grown
under somewhat different conditions; and there would no longer be any
necessity to guard against intercrosses between the individuals of the
same variety.
MARRIAGES OF FIRST COUSINS.
[Page 460.]
With respect to mankind, my son George has endeavored to discover by
a statistical investigation whether the marriages of first cousins
are at all injurious, although this is a degree of relationship which
would not be objected to in our domestic animals; and he has come to
the conclusion from his own researches, and those of Dr. Mitchell,
that the evidence as to any evil thus caused is conflicting, but on
the whole points to its being very small. From the facts given in this
volume we may infer that with mankind the marriages of nearly related
persons, some of whose parents and ancestors had lived under very
different conditions, would be much less injurious than that of persons
who had always lived in the same place and followed the same habits of
life. Nor can I see reason to doubt that the widely different habits of
life of men and women in civilized nations, especially among the upper
classes, would tend to counterbalance any evil from marriages between
healthy and somewhat closely related persons.
DEVELOPMENT OF THE TWO SEXES IN PLANTS.
[Page 461.]
Under a theoretical point of view it is some gain to science to know
that numberless structures in hermaphrodite plants, and probably
in hermaphrodite animals, are special adaptations for securing an
occasional cross between two individuals; and that the advantages from
such a cross depend altogether on the beings which are united, or their
progenitors, having had their sexual elements somewhat differentiated,
so that the embryo is benefited in the same manner as is a mature plant
or animal by a slight change in its conditions of life, although in a
much higher degree.
Another and more important result may be deduced from my observations.
Eggs and seeds are highly serviceable as a means of dissemination,
but we now know that fertile eggs can be produced without the aid of
the male. There are also many other methods by which organisms can be
propagated asexually. Why then have the two sexes been developed, and
why do males exist which can not themselves produce offspring? The
answer lies, as I can hardly doubt, in the great good which is derived
from the fusion of two somewhat differentiated individuals; and with
the exception of the lowest organisms this is possible only by means
of the sexual elements, these consisting of cells separated from the
body, containing the germs of every part, and capable of being fused
completely together.
It has been shown in the present volume that the offspring from the
union of two distinct individuals, especially if their progenitors
have been subjected to very different conditions, have an immense
advantage in height, weight, constitutional vigor and fertility over
the self-fertilized offspring from one of the same parents. And this
fact is amply sufficient to account for the development of the sexual
elements, that is, for the genesis of the two sexes.
It is a different question why the two sexes are sometimes combined
in the same individual, and are sometimes separated. As with many of
the lowest plants and animals the conjugation of two individuals,
which are either quite similar or in some degree different is a common
phenomenon, it seems probable, as remarked in the last chapter, that
the sexes were primordially separate. The individual which receives
the contents of the other, may be called the female; and the other,
which is often smaller and more locomotive, may be called the male;
though these sexual names ought hardly to be applied as long as the
whole contents of the two forms are blended into one. The object
gained by the two sexes becoming united in the same hermaphrodite form
probably is to allow of occasional or frequent self-fertilization,
so as to insure the propagation of the species, more especially in
the case of organisms affixed for life to the same spot. There does
not seem to be any great difficulty in understanding how an organism,
formed by the conjugation of two individuals which represented the two
incipient sexes, might have given rise by budding first to a monœcious
and then to an hermaphrodite form; and in the case of animals even
without budding to an hermaphrodite form, for the bilateral structure
of animals perhaps indicates that they were aboriginally formed by the
fusion of two individuals.
WHY THE SEXES HAVE BEEN RESEPARATED.
[Page 463.]
It is a more difficult problem why some plants, and apparently all
the higher animals, after becoming hermaphrodites, have since had
their sexes reseparated. This separation has been attributed by
some naturalists to the advantages which follow from a division of
physiological labor. The principle is intelligible when the same organ
has to perform at the same time diverse functions; but it is not
obvious why the male and female glands, when placed in different parts
of the same compound or simple individual, should not perform their
functions equally well as when placed in two distinct individuals. In
some instances the sexes may have been reseparated for the sake of
preventing too frequent self-fertilization; but this explanation does
not seem probable, as the same end might have been gained by other and
simpler means, for instance, dichogamy. It may be that the production
of the male and female reproductive elements and the maturation of
the ovules was too great a strain and expenditure of vital force for
a single individual to withstand, if endowed with a highly complex
organization; and that at the same time there was no need for all the
individuals to produce young, and consequently that no injury, on the
contrary, good, resulted from half of them, or the males, failing to
produce offspring.
COMPARATIVE FERTILITY OF MALE AND FEMALE PLANTS.
[The Different
Forms of
Flowers,
page 290.]
Thirteen bushes (of the spindle-tree) growing near one another in a
hedge consisted of eight females quite destitute of pollen, and of five
hermaphrodites with well-developed anthers. In the autumn the eight
females were well covered with fruit, excepting one which bore only a
moderate number. Of the five hermaphrodites, one bore a dozen or two
fruits, and the remaining four bushes several dozen; but their number
was as nothing compared with those on the female bushes, for a single
branch, between two and three feet in length, from one of the latter,
yielded more than any one of the hermaphrodite bushes. The difference
in the amount of fruit produced by the two sets of bushes is all the
more striking, as from the sketches above given it is obvious that the
stigmas of the polleniferous flowers can hardly fail to receive their
own pollen; while the fertilization of the female flowers depends on
pollen being brought to them by flies and the smaller _Hymenoptera_,
which are far from being such efficient carriers as bees.
I now determined to observe more carefully during successive seasons
some bushes growing in another place about a mile distant. As the
female bushes were so highly productive, I marked only two of them with
the letters A and B, and five polleniferous bushes with the letters C
to G. I may premise that the year 1865 was highly favorable for the
fruiting of all the bushes, especially for the polleniferous ones, some
of which were quite barren, except under such favorable conditions.
The season of 1864 was unfavorable. In 1863 the female A produced “some
fruit”; in 1864 only nine; and in 1865 ninety-seven fruit. The female
B in 1863 was “covered with fruit”; in 1864 it bore twenty-eight; and
in 1865 “innumerable very fine fruits.” I may add that three other
female trees growing close by were observed, but only during 1863, and
they then bore abundantly. With respect to the polleniferous bushes,
the one marked C did not bear a single fruit during the years 1863
and 1864, but during 1865 it produced no less than ninety-two fruit,
which, however, were very poor. I selected one of the finest branches
with fifteen fruit, and these contained twenty seeds, or on an average
1·33 per fruit. I then took by hazard fifteen fruit from an adjoining
female bush, and these contained forty-three seeds; that is, more than
twice as many, or on an average 2·86 per fruit. Many of the fruits
from the female bushes included four seeds, and only one had a single
seed; whereas, not one fruit from the polleniferous bushes contained
four seeds. Moreover, when the two lots of seeds were compared, it was
manifest that those from the female bushes were the larger. The second
polleniferous bush, D, bore in 1863 about two dozen fruit, in 1864 only
three very poor fruit, each containing a single seed; and in 1865,
twenty equally poor fruit. Lastly, the three polleniferous bushes, E,
F, and G, did not produce a single fruit during the three years 1863,
1864, and 1865.
EFFECT OF CLIMATE ON REPRODUCTION.
[Page 293.]
A tendency to the separation of the sexes in the cultivated strawberry
seems to be much more strongly marked in the United States than in
Europe; and this appears to be the result of the direct action of
climate on the reproductive organs. In the best account which I have
seen, it is stated that many of the varieties in the United States
consist of three forms, namely, females, which produce a heavy crop
of fruit; of hermaphrodites, which “seldom produce other than a very
scanty crop of inferior and imperfect berries”; and of males, which
produce none. The most skillful cultivators plant “seven rows of female
plants, then one row of hermaphrodites, and so on throughout the
field.” The males bear large, the hermaphrodites mid-sized, and the
females small flowers. The latter plants produce few runners, while the
two other forms produce many; consequently, as has been observed both
in England and in the United States, the polleniferous forms increase
rapidly and tend to supplant the females. We may therefore infer that
much more vital force is expended in the production of ovules and fruit
than in the production of pollen.
CAUSES OF STERILITY AMONG PLANTS.
[The Different
Forms of
Flower,
page 345.]
If the sexual elements belonging to the same form are united, the
union is an illegitimate one, and more or less sterile. With dimorphic
species two illegitimate unions, and with trimorphic species twelve are
possible. There is reason to believe that the sterility of these unions
has not been specially acquired, but follows as an incidental result
from the sexual elements of the two or three forms having been adapted
to act on one another in a particular manner, so that any other kind
of union is inefficient, like that between distinct species. Another
and still more remarkable incidental result is that the seedlings from
an illegitimate union are often dwarfed and more or less completely
barren, like hybrids from the union of two widely distinct species.
AN “IDEAL TYPE” OR INEVITABLE MODIFICATION?
[Fertilization
of Orchids
by Insects,
page 245.]
It is interesting to look at one of the magnificent exotic species
(orchids), or, indeed, at one of our humblest forms, and observe
how profoundly it has been modified, as compared with all ordinary
flowers--with its great labellum, formed of one petal and two petaloid
stamens; with its singular pollen-masses, hereafter to be referred to;
with its column formed of seven cohering organs, of which three alone
perform their proper function, namely, one anther and two generally
confluent stigmas; with the third stigma modified into the rostellum
and incapable of being fertilized; and with three of the anthers no
longer functionally active, but serving either to protect the pollen
of the fertile anther or to strengthen the column, or existing as mere
rudiments, or entirely suppressed. What an amount of modification,
cohesion, abortion, and change of function do we here see! Yet hidden
in that column, with its surrounding petals and sepals, we know that
there are fifteen groups of vessels, arranged three within three, in
alternate order, which probably have been preserved to the present
time from being developed at a very early period of growth, before the
shape or existence of any part of the flower is of importance for the
well-being of the plant.
Can we feel satisfied by saying that each orchid was created, exactly
as we now see it, on a certain “ideal type”; that the omnipotent
Creator, having fixed on one plan for the whole order, did not depart
from this plan; that he, therefore, made the same organ to perform
diverse functions--often of trifling importance compared with
their proper function--converted other organs into mere purposeless
rudiments, and arranged all as if they had to stand separate, and then
made them cohere? Is it not a more simple and intelligible view that
all the _Orchideæ_ owe what they have in common to descent from some
monocotyledonous plant, which, like so many other plants of the same
class, possessed fifteen organs, arranged alternately, three within
three, in five whorls; and that the now wonderfully changed structure
of the flower is due to a long course of slow modification--each
modification having been preserved which was useful to the plant,
during the incessant changes to which the organic and inorganic world
has been exposed?
SPECIAL ADAPTATIONS TO A CHANGING PURPOSE.
[Fertilization
of Orchids,
page 282.]
It has, I think, been shown that the _Orchideæ_ exhibit an almost
endless diversity of beautiful adaptations. When this or that part has
been spoken of as adapted for some special purpose, it must not be
supposed that it was originally always formed for this sole purpose.
The regular course of events seems to be, that a part which originally
served for one purpose becomes adapted by slow changes for widely
different purposes. To give an instance: in all the _Ophreæ_, the long
and nearly rigid caudicle manifestly serves for the application of
the pollen-grains to the stigma, when the pollinia are transported by
insects to another flower; and the anther opens widely in order that
the pollinium should be easily withdrawn; but, in the _Bee ophrys_, the
caudicle, by a slight increase in length and decrease in its thickness,
and by the anther opening a little more widely, becomes specially
adapted for the very different purpose of self-fertilization, through
the combined aid of the weight of the pollen-mass and the vibration
of the flower when moved by the wind. Every gradation between these
two states is possible--of which we have a partial instance in _O.
aranifera_.
Again, the elasticity of the pedicel of the pollinium in some _Vandeæ_
is adapted to free the pollen-masses from their anther-cases; but, by
a further slight modification, the elasticity of the pedicel becomes
specially adapted to shoot out the pollinium with considerable force,
so as to strike the body of the visiting insect. The great cavity in
the labellum of many _Vandeæ_ is gnawed by insects, and thus attracts
them; but in _Mormodes ignea_ it is greatly reduced in size, and serves
in chief part to keep the labellum in its new position on the summit
of the column. From the analogy of many plants we may infer that a
long, spur-like nectary is primarily adapted to secrete and hold a
store of nectar; but in many orchids it has so far lost this function
that it contains fluid only in the intercellular spaces. In those
orchids in which the nectary contains both free nectar and fluid in the
intercellular spaces, we can see how a transition from the one state
to the other could be effected, namely, by less and less nectar being
secreted from the inner membrane, with more and more retained within
the intercellular spaces. Other analogous cases could be given.
Although an organ may not have been originally formed for some special
purpose, if it now serves for this end, we are justified in saying that
it is specially adapted for it. On the same principle, if a man were to
make a machine for some special purpose, but were to use old wheels,
springs, and pulleys, only slightly altered, the whole machine, with
all its parts, might be said to be specially contrived for its present
purpose. Thus throughout nature almost every part of each living being
has probably served, in a slightly modified condition, for diverse
purposes, and has acted in the living machinery of many ancient and
distinct specific forms.
In my examination of orchids, hardly any fact has struck me so much as
the endless diversities of structure--the prodigality of resources--for
gaining the very same end, namely, the fertilization of one flower by
pollen from another plant. This fact is to a large extent intelligible
on the principle of natural selection. As all the parts of a flower are
co-ordinated, if slight variations in any one part were preserved from
being beneficial to the plant, then the other parts would generally
have to be modified in some corresponding manner. But these latter
parts might not vary at all, or they might not vary in a fitting
manner, and these other variations, whatever their nature might be,
which tended to bring all the parts into more harmonious action with
one another, would be preserved by natural selection.
AN ILLUSTRATION.
[Page 284.]
To give a simple illustration: in many orchids the ovarium (but
sometimes the foot-stalk) becomes for a period twisted, causing the
labellum to assume the position of a lower petal, so that insects can
easily visit the flower; but from slow changes in the form or position
of the petals, or from new sorts of insects visiting the flowers, it
might be advantageous to the plant that the labellum should resume
its normal position on the upper side of the flower, as is actually
the case with _Malaxis paludosa_, and some species of _Catasetum_,
etc. This change, it is obvious, might be simply effected by the
continued selection of varieties which had their ovaria less and less
twisted; but, if the plant only afforded varieties with the ovarium
more twisted, the same end could be attained by the selection of such
variations, until the flower was turned completely round on its axis.
This seems to have actually occurred with _Malaxis paludosa_, for the
labellum has acquired its present upward position by the ovarium being
twisted twice as much as is usual.
Again, we have seen that in most _Vandeæ_ there is a plain relation
between the depth of the stigmatic chamber and the length of the
pedicel, by which the pollen-masses are inserted; now, if the chamber
became slightly less deep from any change in the form of the column, or
other unknown cause, the mere shortening of the pedicel would be the
simplest corresponding change; but, if the pedicel did not happen to
vary in shortness, the slightest tendency to its becoming bowed from
elasticity, as in _Phalænopsis_, or to a backward hygrometric movement,
as in one of the _Maxillarias_, would be preserved, and the tendency
would be continually augmented by selection; thus the pedicel, as far
as its action is concerned, would be modified in the same manner as if
it had been shortened. Such processes carried on during many thousand
generations in various ways, would create an endless diversity of
co-adapted structures in the several parts of the flower for the same
general purpose. This view affords, I believe, the key which partly
solves the problem of the vast diversity of structure adapted for
closely analogous ends in many large groups of organic beings.
AS INTERESTING ON THE THEORY OF DEVELOPMENT AS ON THAT OF DIRECT
INTERPOSITION.
[Page 285.]
The more I study nature, the more I become impressed, with
ever-increasing force, that the contrivances and beautiful adaptations
slowly acquired through each part occasionally varying in a slight
degree but in many ways, with the preservation of those variations
which were beneficial to the organism under complex and ever-varying
conditions of life, transcend in an incomparable manner the
contrivances and adaptations which the most fertile imagination of man
could invent.
The use of each trifling detail of structure is far from a barren
search to those who believe in natural selection. When a naturalist
casually takes up the study of an organic being, and does not
investigate its whole life (imperfect though that study will ever be),
he naturally doubts whether each trifling point can be of any use, or,
indeed, whether it be due to any general law. Some naturalists believe
that numberless structures have been created for the sake of mere
variety and beauty--much as a workman would make different patterns.
I, for one, have often and often doubted whether this or that detail
of structure in many of the _Orchideæ_ and other plants could be of
any service; yet, if of no good, these structures could not have
been modeled by the natural preservation of useful variations; such
details can only be vaguely accounted for by the direct action of the
conditions of life, or the mysterious laws of correlated growth.
[Fertilization
of Orchids,
page 2.]
This treatise affords me also an opportunity of attempting to show that
the study of organic beings may be as interesting to an observer who is
fully convinced that the structure of each is due to secondary laws as
to one who views every trifling detail of structure as the result of
the direct interposition of the Creator.
THE SLEEP OF THE PLANTS.
[The Power
of Movement
in Plants,
page 280.]
The so-called sleep of leaves is so conspicuous a phenomenon that it
was observed as early as the time of Pliny; and since Linnæus published
his famous essay, “Somnus Plantarum,” it has been the subject of
several memoirs. Many flowers close at night, and these are likewise
said to sleep; but we are not here concerned with their movements,
for although effected by the same mechanism as in the case of young
leaves, namely, unequal growth on the opposite sides (as first proved
by Pfeffer), yet they differ essentially in being excited chiefly by
changes of temperature instead of light; and in being effected, as far
as we can judge, for a different purpose. Hardly any one supposes that
there is any real analogy between the sleep of animals and that of
plants, whether of leaves or flowers. It seems, therefore, advisable
to give a distinct name to the so-called sleep-movements of plants.
These have also generally been confounded, under the term “periodic,”
with the slight daily rise and fall of leaves, as described in the
fourth chapter; and this makes it all the more desirable to give some
distinct name to sleep-movements. Nyctitropism and nyctitropic, i. e.,
night-turning, may be applied both to leaves and flowers, and will be
occasionally used by us; but it would be best to confine the term to
leaves.
* * * * *
[Page 281.]
Leaves, when they go to sleep, move either upward or downward, or, in
the case of the leaflets of compound leaves, forward, that is, toward
the apex of the leaf, or backward, that is, toward its base; or,
again, they may rotate on their own axis without moving either upward
or downward. But in almost every case the plane of the blade is so
placed as to stand nearly or quite vertically at night. Therefore the
apex, or the base, or either lateral edge, may be directed toward the
zenith. Moreover, the upper surface of each leaf, and more especially
of each leaflet, is often brought into close contact with that of the
opposite one; and this is sometimes effected by singularly complicated
movements. This fact suggests that the upper surface requires more
protection than the lower one. For instance, the terminal leaflet in
trifolium, after turning up at night so as to stand vertically, often
continues to bend over until the upper surface is directed downward,
while the lower surface is fully exposed to the sky; and an arched roof
is thus formed over the two lateral leaflets, which have their upper
surfaces pressed closely together. Here we have the unusual case of one
of the leaflets not standing vertically, or almost vertically, at night.
Considering that leaves in assuming their nyctitropic positions often
move through an angle of 90°; that the movement is rapid in the
evening; that in some cases it is extraordinarily complicated; that
with certain seedlings, old enough to bear true leaves, the cotyledons
move vertically upward at night, while at the same time the leaflets
move vertically downward; and that in the same genus the leaves or
cotyledons of some species move upward, while those of other species
move downward--from these and other such facts, it is hardly possible
to doubt that plants must derive some great advantage from such
remarkable powers of movement.
SELF-PROTECTION DURING SLEEP.
[Page 284.]
The fact that the leaves of many plants place themselves at night in
widely different positions from what they hold during the day, but
with the one point in common, that their upper surfaces avoid facing
the zenith, often with the additional fact that they come into close
contact with opposite leaves or leaflets, clearly indicates, as it
seems to us, that the object gained is the protection of the upper
surfaces from being chilled at night by radiation. There is nothing
improbable in the upper surface needing protection more than the lower,
as the two differ in function and structure. All gardeners know that
plants suffer from radiation. It is this, and not cold winds, which
the peasants of Southern Europe fear for their olives. Seedlings are
often protected from radiation by a very thin covering of straw; and
fruit-trees on walls by a few fir-branches, or even by a fishing-net,
suspended over them. There is a variety of the gooseberry, the flowers
of which, from being produced before the leaves, are not protected by
them from radiation, and consequently often fail to yield fruit. An
excellent observer has remarked that one variety of the cherry has
the petals of its flowers much curled backward, and after a severe
frost all the stigmas were killed; while, at the same time, in another
variety with incurved petals, the stigmas were not in the least injured.
* * * * *
[Page 285.]
We are far from doubting that an additional advantage may be thus
gained; and we have observed with several plants, for instance,
_Desmodium gyrans_, that while the blade of the leaf sinks vertically
down at night, the petiole rises, so that the blade has to move through
a greater angle in order to assume its vertical position than would
otherwise have been necessary; but with the result that all the leaves
on the same plant are crowded together, as if for mutual protection.
We doubted at first whether radiation would affect in any important
manner objects so thin as are many cotyledons and leaves, and more
especially affect differently their upper and lower surfaces; for,
although the temperature of their upper surfaces would undoubtedly fall
when freely exposed to a clear sky, yet we thought that they would so
quickly acquire by conduction the temperature of the surrounding air,
that it could hardly make any sensible difference to them whether they
stood horizontally, and radiated into the open sky, or vertically, and
radiated chiefly in a lateral direction toward neighboring plants and
other objects. We endeavored, therefore, to ascertain something on
this head, by preventing the leaves of several plants from going to
sleep, and by exposing to a clear sky, when the temperature was beneath
the freezing-point, these as well as the other leaves on the same
plants, which had already assumed their nocturnal vertical position.
Our experiments show that leaves thus compelled to remain horizontal
at night suffered much more injury from frost than those which were
allowed to assume their normal vertical position. It may, however, be
said that conclusions drawn from such observations are not applicable
to sleeping plants, the inhabitants of countries where frosts do not
occur. But in every country, and at all seasons, leaves must be exposed
to nocturnal chills through radiation, which might be in some degree
injurious to them, and which they would escape by assuming a vertical
position.
* * * * *
[The Power
of Movement
in Plants,
page 403.]
Any one who had never observed continuously a sleeping plant would
naturally suppose that the leaves moved only in the evening when going
to sleep, and in the morning when awaking; but he would be quite
mistaken, for we have found no exception to the rule that leaves which
sleep continue to move during the whole twenty-four hours; they move,
however, more quickly when going to sleep and when awaking than at
other times.
INFLUENCE OF LIGHT UPON PLANTS.
[The Power
of Movement
in Plants,
page 565.]
The extreme sensitiveness of certain seedlings to light is highly
remarkable. The cotyledons of _Phalaris_ became curved toward a distant
lamp, which emitted so little light that a pencil held vertically close
to the plants did not cast any shadow which the eye could perceive on a
white card. These cotyledons, therefore, were affected by a difference
in the amount of light on their two sides, which the eye could not
distinguish. The degree of their curvature within a given time toward
a lateral light did not correspond at all strictly with the amount of
light which they received; the light not being at any time in excess.
They continued for nearly half an hour to bend toward a lateral light,
after it had been extinguished. They bend with remarkable precision
toward it, and this depends on the illumination of one whole side, or
on the obscuration of the whole opposite side. The difference in the
amount of light which plants at any time receive in comparison with
what they have shortly before received seems in all cases to be the
chief exciting cause of those movements which are influenced by light.
Thus seedlings brought out of darkness bend toward a dim lateral light,
sooner than others which had previously been exposed to daylight. We
have seen several analogous cases with the nyctitropic movements of
leaves. A striking instance was observed in the case of the periodic
movements of the cotyledons of a cassia: in the morning a pot was
placed in an obscure part of a room, and all the cotyledons rose up
closed; another pot had stood in the sunlight, and the cotyledons of
course remained expanded; both pots were now placed close together in
the middle of the room, and the cotyledons which had been exposed to
the sun immediately began to close, while the others opened; so that
the cotyledons in the two pots moved in exactly opposite directions
while exposed to the same degree of light.
We found that if seedlings, kept in a dark place, were laterally
illuminated by a small wax-taper for only two or three minutes at
intervals of about three quarters of an hour, they all became bowed
to the point where the taper had been held. We felt much surprised at
this fact, and, until we had read Wiesner’s observations, we attributed
it to the after-effects of the light; but he has shown that the same
degree of curvature in a plant may be induced in the course of an hour
by several interrupted illuminations lasting altogether for twenty
minutes as by a continuous illumination of sixty minutes. We believe
that this case, as well as our own, may be explained by the excitement
from light being due not so much to its actual amount, as to the
difference in amount from that previously received; and in our case
there were repeated alternations from complete darkness to light. In
this and in several of the above-specified respects, light seems to act
on the tissues of plants almost in the same manner as it does on the
nervous system of animals.
INFLUENCE OF GRAVITATION UPON PLANTS.
[Page 567.]
Gravitation excites plants to bend away from the center of the earth,
or toward it, or to place themselves in a transverse position with
respect to it. Although it is impossible to modify in any direct
manner the attraction of gravity, yet its influence could be moderated
indirectly, in the several ways described in the tenth chapter; and
under such circumstances the same kind of evidence as that given in the
chapter on heliotropism showed in the plainest manner that apogeotropic
and geotropic, and probably diageotropic movements, are all modified
forms of circumnutation.
Different parts of the same plant and different species are affected by
gravitation in widely different degrees and manners. Some plants and
organs exhibit hardly a trace of its action. Young seedlings, which,
as we know, circumnutate rapidly, are eminently sensitive; and we have
seen the hypocotyl of _Beta_ bending upward through 109° in three hours
and eight minutes. The after-effects of apogeotropism last for above
half an hour; and horizontally-laid hypocotyls are sometimes thus
carried temporarily beyond an upright position. The benefits derived
from geotropism, apogeotropism, and diageotropism, are generally so
manifest that they need not be specified. With the flower-peduncles
of _Oxalis_, epinasty causes them to bend down, so that the ripening
pods may be protected by the calyx from the rain. Afterward they are
carried upward by apogeotropism in combination with hyponasty, and are
thus enabled to scatter their seeds over a wider space. The capsules
and flower-heads of some plants are bowed downward through geotropism,
and they then bury themselves in the earth for the protection and slow
maturation of the seeds. This burying process is much facilitated by
the rocking movement due to circumnutation.
In the case of the radicles of several, probably of all seedling
plants, sensitiveness to gravitation is confined to the tip, which
transmits an influence to the adjoining upper part, causing it to bend
toward the center of the earth. That there is transmission of this
kind was proved in an interesting manner when horizontally extended
radicles of the bean were exposed to the attraction of gravity for an
hour or an hour and a half, and their tips were then amputated. Within
this time no trace of curvature was exhibited, and the radicles were
now placed pointing vertically downward; but an influence had already
been transmitted from the tip to the adjoining part, for it soon became
bent to one side, in the same manner as would have occurred had the
radicle remained horizontal and been still acted on by geotropism.
Radicles thus treated continued to grow out horizontally for two or
three days, until a new tip was reformed; and this was then acted on by
geotropism, and the radicle became curved perpendicularly downward.
THE POWER OF DIGESTION IN PLANTS.
[Insectivorous
Plants,
page 85.]
As we have seen that nitrogenous fluids act very differently on the
leaves of _Drosera_ from non-nitrogenous fluids, and as the leaves
remain clasped for a much longer time over various organic bodies than
over inorganic bodies, such as bits of glass, cinder, wood, etc., it
becomes an interesting inquiry whether they can only absorb matter
already in solution, or render it soluble; that is, have the power
of digestion. We shall immediately see that they certainly have this
power, and that they act on albuminous compounds in exactly the same
manner as does the gastric juice of mammals; the digested matter being
afterward absorbed. This fact, which will be clearly proved, is a
wonderful one in the physiology of plants.
* * * * *
[Page 86.]
It may be well to premise, for the sake of any reader who knows
nothing about the digestion of albuminous compounds by animals, that
this is effected by means of a ferment, pepsin, together with weak
hydrochloric acid, though almost any acid will serve. Yet neither
pepsin nor an acid by itself has any such power. We have seen that
when the glands of the disk are excited by the contact of any object,
especially of one containing nitrogenous matter, the outer tentacles
and often the blade become inflected; the leaf being thus converted
into a temporary cup or stomach. At the same time the discal glands
secrete more copiously, and the secretion becomes acid. Moreover,
they transmit some influence to the glands of the exterior tentacles,
causing them to pour forth a more copious secretion, which also becomes
acid or more acid than it was before.
As this result is an important one, I will give the evidence. The
secretion of many glands on thirty leaves, which had not been in
any way excited, was tested with litmus-paper; and the secretion of
twenty-two of these leaves did not in the least affect the color,
whereas that of eight caused an exceedingly feeble and sometimes
doubtful tinge of red. Two other old leaves, however, which appeared
to have been inflected several times, acted much more decidedly on
the paper. Particles of clean glass were then placed on five of the
leaves, cubes of albumen on six, and bits of raw meat on three, on none
of which was the secretion at this time in the least acid. After an
interval of twenty-four hours, when almost all the tentacles on these
fourteen leaves had become more or less inflected, I again tested the
secretion, selecting glands which had not as yet reached the center or
touched any object, and it was now plainly acid. The degree of acidity
of the secretion varied somewhat on the glands of the same leaf. On
some leaves a few tentacles did not, from some unknown cause, become
inflected, as often happens; and in five instances their secretion
was found not to be in the least acid; while the secretion of the
adjoining and inflected tentacles on the same leaf was decidedly acid.
With leaves excited by particles of glass placed on the central glands,
the secretion which collects on the disk beneath them was much more
strongly acid than that poured forth from the exterior tentacles, which
were as yet only moderately inflected. When bits of albumen (and this
is naturally alkaline) or bits of meat were placed on the disk, the
secretion collected beneath them was likewise strongly acid. As raw
meat moistened with water is slightly acid, I compared its action on
litmus-paper before it was placed on the leaves, and afterward when
bathed in the secretion; and there could not be the least doubt that
the latter was very much more acid. I have indeed tried hundreds of
times the state of the secretion on the disks of leaves which were
inflected over various objects, and never failed to find it acid. We
may, therefore, conclude that the secretion from unexcited leaves,
though extremely viscid, is not acid or only slightly so, but that it
becomes acid, or much more strongly so, after the tentacles have begun
to bend over any inorganic or organic object; and still more strongly
acid after the tentacles have remained for some time closely clasped
over any object.
I may here remind the reader that the secretion appears to be to a
certain extent antiseptic, as it checks the appearance of mold and
infusoria, thus preventing for a time the discoloration and decay of
such substances as the white of an egg, cheese, etc. It therefore acts
like the gastric juice of the higher animals, which is known to arrest
putrefaction by destroying the microzymes.
* * * * *
[Page 98.]
Cubes of about one twentieth of an inch (1·27 millimetre) of moderately
roasted meat were placed on five leaves, which became in twelve hours
closely inflected. After forty-eight hours I gently opened one leaf,
and the meat now consisted of a minute central sphere, partially
digested, and surrounded by a thick envelope of transparent viscid
fluid. The whole, without being much disturbed, was removed and placed
under the microscope. In the central part the transverse striæ on the
muscular fibers were quite distinct; and it was interesting to observe
how gradually they disappeared, when the same fiber was traced into
the surrounding fluid. They disappeared by the striæ being replaced by
transverse lines formed of excessively minute dark points, which toward
the exterior could be seen only under a very high power; and ultimately
these points were lost.
* * * * *
[Page 134.]
Finally, the experiments recorded in this chapter show us that there
is a remarkable accordance in the power of digestion between the
gastric juice of animals, with its pepsin and hydrochloric acid, and
the secretion of _Drosera_ with its ferment and acid belonging to the
acetic series. We can, therefore, hardly doubt that the ferment in both
cases is closely similar.
DIVERSE MEANS BY WHICH PLANTS GAIN THEIR SUBSISTENCE.
[Insectivorous
Plants,
page 452.]
Ordinary plants of the higher classes procure the requisite inorganic
elements from the soil by means of their roots, and absorb carbonic
acid from the atmosphere by means of their leaves and stems. But we
have seen in a previous part of this work that there is a class of
plants which digest and afterward absorb animal matter, namely, all
the _Droseraceæ_, _Pinguicula_, and, as discovered by Dr. Hooker,
_Nepenthes_, and to this class other species will almost certainly soon
be added. These plants can dissolve matter out of certain vegetable
substances, such as pollen, seeds, and bits of leaves. No doubt their
glands likewise absorb the salts of ammonia brought to them by the
rain. It has also been shown that some other plants can absorb ammonia
by their glandular hairs; and these will profit by that brought to them
by the rain. There is a second class of plants which, as we have just
seen, can not digest, but absorb, the products of the decay of the
animals which they capture, namely, _Utricularia_ and its close allies;
and, from the excellent observations of Dr. Mellichamp and Dr. Canby,
there can scarcely be a doubt that _Sarracenia_ and _Darlingtonia_ may
be added to this class, though the fact can hardly be considered as yet
fully proved. There is a third class of plants which feed, as is now
generally admitted, on the products of the decay of vegetable matter,
such as the bird’s-nest orchid (_Neottia_), etc. Lastly, there is the
well-known fourth class of parasites (such as the mistletoe), which
are nourished by the juices of living plants. Most, however, of the
plants belonging to these four classes obtain part of their carbon,
like ordinary species, from the atmosphere. Such are the diversified
means, as far as at present known, by which higher plants gain their
subsistence.
HOW A PLANT PREYS UPON ANIMALS.
_The genus described is Genlisea ornata._
[Insectivorous
Plants,
page 446.]
The utricle is formed by a slight enlargement of the narrow blade of
the leaf. A hollow neck, no less than fifteen times as long as the
utricle itself, forms a passage from the transverse slit-like orifice
into the cavity of the utricle. A utricle which measured 1/36 of an
inch (·795 millimetre) in its longer diameter had a neck 15/36 (10·583
millimetres) in length, and 1/100 of an inch (·254 millimetre) in
breadth. On each side of the orifice there is a long spiral arm, or
tube; the structure of which will be best understood by the following
illustration: Take a narrow ribbon and wind it spirally round a thin
cylinder, so that the edges come into contact along its whole length;
then pinch up the two edges so as to form a little crest, which will,
of course, wind spirally round the cylinder, like a thread round a
screw. If the cylinder is now removed, we shall have a tube like one of
the spiral arms. The two projecting edges are not actually united, and
a needle can be pushed in easily between them. They are indeed in many
places a little separated, forming narrow entrances into the tube; but
this may be the result of the drying of the specimens. The lamina of
which the tube is formed seems to be a lateral prolongation of the lip
of the orifice; and the spiral line between the two projecting edges
is continuous with the corner of the orifice. If a fine bristle is
pushed down one of the arms, it passes into the top of the hollow neck.
Whether the arms are open or closed at their extremities could not be
determined, as all the specimens were broken; nor does it appear that
Dr. Warming ascertained this point.
So much for the external structure. Internally the lower part of
the utricle is covered with spherical papillæ, formed of four cells
(sometimes eight, according to Dr. Warming), which evidently answer
to the quadrifid processes within the bladders of _Utricularia_.
These papillæ extend a little way up the dorsal and ventral surfaces
of the utricle; and a few, according to Warming may be found in the
upper part. This upper region is covered by many transverse rows,
one above the other, of short, closely approximate hairs, pointing
downward. These hairs have broad bases, and their tips are formed by a
separate cell. They are absent in the lower part of the utricle where
the papillæ abound. The neck is likewise lined throughout its whole
length with transverse rows of long, thin, transparent hairs, having
broad bulbous bases, with similarly constructed sharp points. They
arise from little projecting ridges, formed of rectangular epidermic
cells. The hairs vary a little in length, but their points generally
extend down to the row next below; so that, if the neck is split open
and laid flat, the inner surface resembles a paper of pins--the hairs
representing the pins, and the little transverse ridges representing
the folds of paper through which the pins are thrust. These rows of
hairs are indicated in the previous figure by numerous transverse lines
crossing the neck. The inside of the neck is also studded with papillæ;
those in the lower part are spherical and formed of four cells, as
in the lower part of the utricle; those in the upper part are formed
of two cells, which are much elongated downward beneath their points
of attachment. These two-celled papillæ apparently correspond with
the bifid process in the upper part of the bladders of _Utricularia_.
The narrow transverse orifice is situated between the bases of the
two spiral arms. No valve could be detected here, nor was any such
structure seen by Dr. Warming. The lips of the orifice are armed with
many short, thick, sharply pointed, somewhat incurved hairs or teeth.
The two projecting edges of the spirally-wound lamina, forming the
arms, are provided with short incurved hairs or teeth, exactly like
those on the lips. These project inward at right angles to the spiral
line of junction between the two edges. The inner surface of the lamina
supports two-celled, elongated papillæ, resembling those in the upper
part of the neck, but differing slightly from them, according to
Warming, in their footstalks being formed by prolongations of large
epidermic cells; whereas the papillæ within the neck rest on small
cells sunk amid the larger ones. These spiral arms form a conspicuous
difference between the present genus and _Utricularia_.
Lastly, there is a bundle of spiral vessels which, running up the lower
part of the linear leaf, divides close beneath the utricle. One branch
extends up the dorsal and the other up the ventral side of both the
utricle and neck. Of these two branches, one enters one spiral arm, and
the other branch the other arm.
The utricles contained much _débris_, or dirty matter, which seemed
organic, though no distinct organisms could be recognized. It is,
indeed, scarcely possible that any object could enter the small orifice
and pass down the long, narrow neck, except a living creature. Within
the necks, however, of some specimens, a worm, with retracted horny
jaws, the abdomen of some articulate animal, and specks of dirt,
probably the remnants of other minute creatures, were found. Many of
the papillæ within both the utricles and necks were discolored, as if
they had absorbed matter.
From this description it is sufficiently obvious how genlisea
secures its prey. Small animals entering the narrow orifice--but
what induces them to enter is not known any more than in the case of
_Utricularia_--would find their egress rendered difficult by the sharp
incurved hairs on the lips, and, as soon as they passed some way down
the neck, it would be scarcely possible for them to return, owing to
the many transverse rows of long, straight, downward-pointing hairs,
together with the ridges from which these project. Such creatures
would, therefore, perish either within the neck or utricle; and the
quadrifid and bifid papillæ would absorb matter from their decayed
remains. The transverse rows of hairs are so numerous that they seem
superfluous merely for the sake of preventing the escape of prey,
and, as they are thin and delicate, they probably serve as additional
absorbents, in the same manner as the flexible bristles on the infolded
margins of the leaves of aldrovanda. The spiral arms, no doubt, act as
accessory traps. Until fresh leaves are examined, it can not be told
whether the line of junction of the spirally-wound lamina is a little
open along its whole course or only in parts, but a small creature
which forced its way into the tube at any point would be prevented from
escaping by the incurved hairs, and would find an open path down the
tube into the neck, and so into the utricle. If the creature perished
within the spiral arms, its decaying remains would be absorbed and
utilized by the bifid papillæ. We thus see that animals are captured
by genlisea, not by means of an elastic valve, as with the foregoing
species, but by a contrivance resembling an eel-trap, though more
complex.
II.
THE PART PLAYED BY WORMS IN THE HISTORY OF THIS PLANET.
[The Formation
of Vegetable
Mold through
the Action of
Earthworms,
page 305.]
Worms have played a more important part in the history of the world
than most persons would at first suppose. In almost all humid countries
they are extraordinarily numerous, and for their size possess great
muscular power. In many parts of England a weight of more than ten
tons (10,516 kilogrammes) of dry earth annually passes through their
bodies and is brought to the surface on each acre of land; so that the
whole superficial bed of vegetable mold passes through their bodies
in the course of every few years. From the collapsing of the old
burrows the mold is in constant though slow movement, and the particles
composing it are thus rubbed together. By these means fresh surfaces
are continually exposed to the action of the carbonic acid in the
soil, and of the humus-acids which appear to be still more efficient
in the decomposition of rocks. The generation of the humus-acids
is probably hastened during the digestion of the many half-decayed
leaves which worms consume. Thus the particles of earth, forming the
superficial mold, are subjected to conditions eminently favorable for
their decomposition and disintegration. Moreover, the particles of
the softer rocks suffer some amount of mechanical trituration in the
muscular gizzards of worms, in which small stones serve as mill-stones.
The finely levigated castings, when brought to the surface in a moist
condition, flow during rainy weather down any moderate slope; and the
smaller particles are washed far down even a gently inclined surface.
Castings when dry often crumble into small pellets, and these are apt
to roll down any sloping surface. Where the land is quite level and
is covered with herbage, and where the climate is humid so that much
dust can not be blown away, it appears at first sight impossible that
there should be any appreciable amount of subaërial denudation; but
worm-castings are blown, especially while moist and viscid, in one
uniform direction by the prevalent winds which are accompanied by
rain. By these several means the superficial mold is prevented from
accumulating to a great thickness; and a thick bed of mold checks in
many ways the disintegration of the underlying rocks and fragments of
rock.
The removal of worm-castings by the above means leads to results which
are far from insignificant. It has been shown that a layer of earth,
·2 of an inch in thickness, is in many places annually brought to the
surface per acre; and if a small part of this amount flows, or rolls,
or is washed, even for a short distance down every inclined surface, or
is repeatedly blown in one direction, a great effect will be produced
in the course of ages. It was found by measurements and calculations
that on a surface with a mean inclination of 9° 26’, 2·4 cubic inches
of earth which had been ejected by worms crossed, in the course of a
year, a horizontal line one yard in length; so that 240 cubic inches
would cross a line a hundred yards in length. This latter amount in a
damp state would weigh eleven and a half pounds. Thus a considerable
weight of earth is continually moving down each side of every valley,
and will in time reach its bed. Finally, this earth will be transported
by the streams flowing in the valleys into the ocean, the great
receptacle for all matter denuded from the land. It is known from the
amount of sediment annually delivered into the sea by the Mississippi,
that its enormous drainage-area must on an average be lowered ·00263 of
an inch each year; and this would suffice in four and a half million
years to lower the whole drainage-area to the level of the sea-shore.
So that, if a small fraction of the layer of fine earth, ·2 of an
inch in thickness, which is annually brought to the surface by worms,
is carried away, a great result can not fail to be produced within a
period which no geologist considers extremely long.
THEY PRESERVE VALUABLE RUINS.
[Page 308.]
Archæologists ought to be grateful to worms, as they protect and
preserve for an indefinitely long period every object, not liable to
decay, which is dropped on the surface of the land, by burying it
beneath their castings. Thus, also, many elegant and curious tesselated
pavements and other ancient remains have been preserved; though no
doubt the worms have in these cases been largely aided by earth washed
and blown from the adjoining land, especially when cultivated. The old
tesselated pavements have, however, often suffered by having subsided
unequally from being unequally undermined by the worms. Even old
massive walls may be undermined and subside; and no building is in this
respect safe, unless the foundations lie six or seven feet beneath the
surface, at a depth at which worms can not work. It is probable that
many monoliths and some old walls have fallen down from having been
undermined by worms.
THEY PREPARE THE GROUND FOR SEED.
[Page 309.]
Worms prepare the ground in an excellent manner for the growth of
fibrous-rooted plants and for seedlings of all kinds. They periodically
expose the mold to the air, and sift it so that no stones larger than
the particles which they can swallow are left in it. They mingle the
whole intimately together, like a gardener who prepares fine soil for
his choicest plants. In this state it is well fitted to retain moisture
and to absorb all soluble substances, as well as for the process of
nitrification. The bones of dead animals, the harder parts of insects,
the shells of land-mollusks, leaves, twigs, etc., are before long all
buried beneath the accumulating castings of worms, and are thus brought
in a more or less decayed state within reach of the roots of plants.
Worms likewise drag an infinite number of dead leaves and other parts
of plants into their burrows, partly for the sake of plugging them up
and partly as food.
The leaves which are dragged into the burrows as food, after being torn
into the finest shreds, partially digested, and saturated with the
intestinal and urinary secretions, are commingled with much earth. This
earth forms the dark-colored, rich humus which almost everywhere covers
the surface of the land with a fairly well-defined layer or mantle.
Von Hensen placed two worms in a vessel eighteen inches in diameter,
which was filled with sand, on which fallen leaves were strewed; and
these were soon dragged into their burrows to a depth of three inches.
After about six weeks an almost uniform layer of sand, a centimetre
(·4 inch) in thickness, was converted into humus by having passed
through the alimentary canals of these two worms. It is believed by
some persons that worm-burrows, which often penetrate the ground almost
perpendicularly to a depth of five or six feet, materially aid in its
drainage; notwithstanding that the viscid castings piled over the
mouths of the burrows prevent or check the rain-water directly entering
them. They allow the air to penetrate deeply into the ground. They also
greatly facilitate the downward passage of roots of moderate size; and
these will be nourished by the humus with which the burrows are lined.
Many seeds owe their germination to having been covered by castings;
and others buried to a considerable depth beneath accumulated castings
lie dormant, until at some future time they are accidentally uncovered
and germinate.
* * * * *
[Page 313.]
When we behold a wide, turf-covered expanse, we should remember that
its smoothness, on which so much of its beauty depends, is mainly due
to all the inequalities having been slowly leveled by worms. It is
a marvelous reflection that the whole of the superficial mold over
any such expanse has passed, and will again pass, every few years
through the bodies of worms. The plow is one of the most ancient and
most valuable of man’s inventions; but long before he existed the
land was in fact regularly plowed, and still continues to be thus
plowed, by earth-worms. It may be doubted whether there are many other
animals which have played so important a part in the history of the
world as have these lowly organized creatures. Some other animals,
however, still more lowly organized, namely corals, have done far more
conspicuous work in having constructed innumerable reefs and islands in
the great oceans; but these are almost confined to the tropical zones.
INTELLIGENCE OF WORMS.
[Page 91.]
We can hardly escape from the conclusion that worms show some degree
of intelligence in their manner of plugging up their burrows. Each
particular object is seized in too uniform a manner, and from causes
which we can generally understand, for the result to be attributed to
mere chance. That every object has not been drawn in by its pointed
end, may be accounted for by labor having been saved through some being
inserted by their broader or thicker ends. No doubt worms are led by
instinct to plug up their burrows; and it might have been expected that
they would have been led by instinct how best to act in each particular
case, independently of intelligence. We see how difficult it is to
judge whether intelligence comes into play, for even plants might
sometimes be thought to be thus directed; for instance, when displaced
leaves redirect their upper surfaces toward the light by extremely
complicated movements and by the shortest course. With animals, actions
appearing due to intelligence may be performed through inherited habit
without any intelligence, although aboriginally thus acquired. Or the
habit may have been acquired through the preservation and inheritance
of beneficial variations of some other habit; and in this case the
new habit will have been acquired independently of intelligence
throughout the whole course of its development. There is no _a priori_
improbability in worms having acquired special instincts through
either of these two latter means. Nevertheless, it is incredible that
instincts should have been developed in reference to objects, such
as the leaves or petioles of foreign plants, wholly unknown to the
progenitors of the worms which act in the described manner. Nor are
their actions so unvarying or inevitable as are most true instincts.
As worms are not guided by special instincts in each particular case,
though possessing a general instinct to plug up their burrows, and, as
chance is excluded, the next most probable conclusion seems to be that
they try in many different ways to draw in objects, and at last succeed
in some one way. But it is surprising that an animal so low in the
scale as a worm should have the capacity for acting in this manner, as
many higher animals have no such capacity.
* * * * *
[Page 95.]
Mr. Romanes, who has specially studied the minds of animals, believes
that we can safely infer intelligence only when we see an individual
profiting by its own experience. Now, if worms try to drag objects into
their burrows first in one way and then in another, until they at last
succeed, they profit at least in each particular instance by experience.
* * * * *
[Page 98.]
One alternative alone is left, namely, that worms, although standing
low in the scale of organization, possess some degree of intelligence.
This will strike every one as very improbable; but it may be doubted
whether we know enough about the nervous system of the lower animals to
justify our natural distrust of such a conclusion. With respect to the
small size of the cerebral ganglia, we should remember what a mass of
inherited knowledge, with some power of adapting means to an end, is
crowded into the minute brain of a worker-ant.
III.
THE LAWS OF VARIABILITY WITH RESPECT TO ANIMALS AND PLANTS.
[The Variation
of Animals and
Plants under
Domestication,
vol. i,
page 3.]
I shall in this volume treat, as fully as my materials permit, the
whole subject of variation under domestication. We may thus hope to
obtain some light, little though it be, on the causes of variability,
on the laws which govern it--such as the direct action of climate and
food, the effects of use and disuse, and of correlation of growth--and
on the amount of change to which domesticated organisms are liable.
* * * * *
Although man does not cause variability and can not even prevent it,
he can select, preserve, and accumulate the variations given to him
by the hand of Nature almost in any way which he chooses; and thus he
can certainly produce a great result. Selection may be followed either
methodically and intentionally, or unconsciously and unintentionally.
Man may select and preserve each successive variation, with the
distinct intention of improving and altering a breed, in accordance
with a preconceived idea; and by thus adding up variations, often so
slight as to be imperceptible by an uneducated eye, he has effected
wonderful changes and improvements. It can, also, be clearly shown
that man, without any intention or thought of improving the breed,
by preserving in each successive generation the individuals which he
prizes most, and by destroying the worthless individuals, slowly,
though surely, induces great changes. As the will of man thus comes
into play, we can understand how it is that domesticated breeds show
adaptation to his wants and pleasures. We can further understand how it
is that domestic races of animals and cultivated races of plants often
exhibit an abnormal character, as compared with natural species; for
they have been modified not for their own benefit, but for that of man.
INHERITED EFFECT OF CHANGED HABITS.
[Origin of
Species,
page 5.]
When we compare the individuals of the same variety or subvariety of
our older cultivated plants and animals, one of the first points which
strikes us is, that they generally differ more from each other than do
the individuals of any one species or variety in a state of nature. And
if we reflect on the vast diversity of the plants and animals which
have been cultivated, and which have varied during all ages under
the most different climates and treatment, we are driven to conclude
that this great variability is due to our domestic productions having
been raised under conditions of life not so uniform as, and somewhat
different from, those to which the parent species had been exposed
under nature.
* * * * *
[Page 8.]
Changed habits produce an inherited effect, as in the period of the
flowering of plants when transported from one climate to another. With
animals the increased use or disuse of parts has had a more marked
influence; thus I find in the domestic duck that the bones of the wing
weigh less and the bones of the leg more, in proportion to the whole
skeleton, than do the same bones in the wild-duck; and this change may
be safely attributed to the domestic duck flying much less, and walking
more, than its wild parents. The great and inherited development of
the udders in cows and goats in countries where they are habitually
milked, in comparison with these organs in other countries, is probably
another instance of the effects of use. Not one of our domestic animals
can be named which has not in some country drooping ears; and the view
which has been suggested that the drooping is due to the disease of the
muscles of the ear, from the animals being seldom much alarmed, seems
probable.
* * * * *
[Page 9.]
From facts collected by Heusinger, it appears that white sheep and pigs
are injured by certain plants, while dark-colored individuals escape,
Professor Wyman has recently communicated to me a good illustration
of this fact: on asking some farmers in Virginia how it was that
all their pigs were black, they informed him that the pigs ate the
paint-root (_Lachnanthes_), which colored their bones pink, and which
caused the hoofs of all but the black varieties to drop off; and one
of the “crackers” (i. e., Virginia squatters) added, “We select the
black members of a litter for raising, as they alone have a good
chance of living.” Hairless dogs have imperfect teeth; long-haired and
coarse-haired animals are apt to have, as is asserted, long or many
horns; pigeons with feathered feet have skin between their outer toes;
pigeons with short beaks have small feet, and those with long beaks
large feet. Hence, if man goes on selecting, and thus augmenting, any
peculiarity, he will almost certainly modify unintentionally other
parts of the structure, owing to the mysterious laws of correlation.
EFFECTS OF THE USE AND DISUSE OF PARTS.
[Origin of
Species,
page 108.]
From the facts alluded to in the first chapter, I think there can be no
doubt that use in our domestic animals has strengthened and enlarged
certain parts, and disuse diminished them, and that such modifications
are inherited. Under free nature we have no standard of comparison by
which to judge of the effects of long-continued use or disuse, for we
know not the parent forms; but many animals possess structures which
can be best explained by the effects of disuse. As Professor Owen has
remarked, there is no greater anomaly in nature than a bird that can
not fly; yet there are several in this state. The logger-headed duck of
South America can only flap along the surface of the water, and has its
wings in nearly the same condition as the domestic Aylesbury duck: it
is a remarkable fact that the young birds, according to Mr. Cunningham,
can fly, while the adults have lost this power. As the larger
ground-feeding birds seldom take flight, except to escape danger, it
is probable that the nearly wingless condition of several birds, now
inhabiting or which lately inhabited several oceanic islands, tenanted
by no beast of prey, has been caused by disuse. The ostrich, indeed,
inhabits continents, and is exposed to danger from which it can not
escape by flight, but it can defend itself by kicking its enemies as
efficiently as many quadrupeds. We may believe that the progenitor
of the ostrich genus had habits like those of the bustard, and that,
as the size and weight of its body were increased during successive
generations, its legs were used more, and its wings less, until they
became incapable of flight.
* * * * *
[Page 109.]
The insects in Madeira which are not ground-feeders, and which, as
certain flower-feeding _Coleoptera_ and _Lepidoptera_, must habitually
use their wings to gain their subsistence, have, as Mr. Wollaston
suspects, their wings not at all reduced, but even enlarged. This is
quite compatible with the action of natural selection. For, when a new
insect first arrived on the island, the tendency of natural selection
to enlarge or to reduce the wings would depend on whether a greater
number of individuals were saved by successfully battling with the
winds, or by giving up the attempt and rarely or never flying. As with
mariners shipwrecked near a coast, it would have been better for the
good swimmers if they had been able to swim still farther, whereas it
would have been better for the bad swimmers if they had not been able
to swim at all and had stuck to the wreck.
The eyes of moles and of some burrowing rodents are rudimentary in
size, and in some cases are quite covered by skin and fur. This state
of the eyes is probably due to gradual reduction from disuse, but
aided, perhaps, by natural selection. In South America a burrowing
rodent--the tuco-tuco, or ctenomys--is even more subterranean in its
habits than the mole; and I was assured by a Spaniard, who had often
caught them, that they were frequently blind. One which I kept alive
was certainly in this condition, the cause, as appeared on dissection,
having been inflammation of the nictitating membrane. As frequent
inflammation of the eyes must be injurious to any animal, and as eyes
are certainly not necessary to animals having subterranean habits, a
reduction in their size, with the adhesion of the eyelids and growth of
fur over them, might in such case be an advantage; and, if so, natural
selection would aid the effects of disuse.
VAGUE ORIGIN OF OUR DOMESTIC ANIMALS.
[Origin of
Species,
page 13.]
In the case of most of our anciently domesticated animals and plants,
it is not possible to come to any definite conclusion whether they
are descended from one or several wild species. The argument mainly
relied on by those who believe in the multiple origin of our domestic
animals is, that we find in the most ancient times, on the monuments
of Egypt, and in the lake-habitations of Switzerland, much diversity
in the breeds; and that some of these ancient breeds closely resemble
or are even identical with, those still existing. But this only throws
far backward the history of civilization, and shows that animals were
domesticated at a much earlier period than has hitherto been supposed.
The lake-inhabitants of Switzerland cultivated several kinds of wheat
and barley, the pea, the poppy for oil, and flax; and they possessed
several domesticated animals. They also carried on commerce with other
nations. All this clearly shows, as Heer has remarked, that they had at
this early age progressed considerably in civilization; and this again
implies a long-continued previous period of less advanced civilization,
during which the domesticated animals, kept by different tribes in
different districts, might have varied and given rise to distinct
races. Since the discovery of flint tools in the superficial formations
of many parts of the world, all geologists believe that barbarian man
existed at an enormously remote period; and we know that at the present
day there is hardly a tribe so barbarous as not to have domesticated at
least the dog.
* * * * *
The origin of most of our domestic animals will probably forever remain
vague.
* * * * *
[Page 12.]
In attempting to estimate the amount of structural difference
between allied domestic races, we are soon involved in doubt, from
not knowing whether they are descended from one or several parent
species. This point, if it could be cleared up, would be interesting;
if, for instance, it could be shown that the greyhound, bloodhound,
terrier, spaniel, and bull-dog, which we all know propagate their
kind truly, were the offspring of any single species. Then such facts
would have great weight in making us doubt about the immutability of
the many closely allied natural species--for instance, of the many
foxes--inhabiting different quarters of the world.
DESCENT OF THE DOMESTIC PIGEON.
[Origin of
Species,
page 17.]
Great as are the differences between the breeds of the pigeon, I am
fully convinced that the common opinion of naturalists is correct,
namely, that all are descended from the rock-pigeon (_Columba livia_),
including under this term several geographical races or sub-species,
which differ from each other in the most trifling respects. As several
of the reasons which have led me to this belief are in some degree
applicable in other cases, I will here briefly give them. If the
several breeds are not varieties, and have not proceeded from the
rock-pigeon, they must have descended from at least seven or eight
aboriginal stocks; for it is impossible to make the present domestic
breeds by the crossing of any lesser number: how, for instance,
could a pouter be produced by crossing two breeds unless one of the
parent-stocks possessed the characteristic enormous crop? The supposed
aboriginal stocks must all have been rock-pigeons--that is, they did
not breed or willingly perch on trees. But besides _C. livia_, with
its geographical sub-species, only two or three other species of
rock-pigeons are known, and these have not any of the characters of the
domestic breeds. Hence the supposed aboriginal stocks must either still
exist in the countries where they were originally domesticated, and yet
be unknown to ornithologists--and this, considering their size, habits,
and remarkable characters, seems improbable--or they must have become
extinct in the wild state. But birds breeding on precipices, and good
fliers, are unlikely to be exterminated; and the common rock-pigeon,
which has the same habits with the domestic breeds, has not been
exterminated even on several of the smaller British islets, or on the
shores of the Mediterranean. Hence the supposed extermination of so
many species having similar habits with the rock-pigeon seems a very
rash assumption. Moreover, the several above-named domesticated breeds
have been transported to all parts of the world, and therefore some of
them must have been carried back again into their native country; but
not one has become wild or feral, though the dovecot-pigeon, which is
the rock-pigeon in a very slightly altered state, has become feral in
several places. Again, all recent experience shows that it is difficult
to get wild animals to breed freely under domestication; yet, on the
hypothesis of the multiple origin of our pigeons, it must be assumed
that at least seven or eight species were so thoroughly domesticated
in ancient times by half-civilized man as to be quite prolific under
confinement.
An argument of great weight, and applicable in several other cases,
is, that the above-specified breeds, though agreeing generally with
the wild rock-pigeon in constitution, habits, voice, coloring, and
in most parts of their structure, yet are certainly highly abnormal
in other parts; we may look in vain through the whole great family
of _Columbidæ_ for a beak like that of the English carrier, or
that of the short-faced tumbler, or barb; for reversed feathers
like those of the Jacobin; for a crop like that of the pouter; for
tail-feathers like those of the fantail. Hence it must be assumed not
only that half-civilized man succeeded in thoroughly domesticating
several species, but that he intentionally or by chance picked out
extraordinarily abnormal species; and, further, that these very species
have since all become extinct or unknown. So many strange contingencies
are improbable in the highest degree.
ORIGIN OF THE DOG.
[Animals and
Plants under
Domestication,
vol. i,
page 15.]
The first and chief point of interest in this chapter is, whether
the numerous domesticated varieties of the dog have descended from a
single wild species, or from several. Some authors believe that all
have descended from the wolf, or from the jackal, or from an unknown
and extinct species. Others again believe, and this of late has been
the favorite tenet, that they have descended from several species,
extinct and recent, more or less commingled together. We shall probably
never be able to ascertain their origin with certainty. Paleontology
does not throw much light on the question, owing, on the one hand, to
the close similarity of the skulls of extinct as well as living wolves
and jackals, and owing, on the other hand, to the great dissimilarity
of the skulls of the several breeds of the domestic dogs. It seems,
however, that remains have been found in the later tertiary deposits
more like those of a large dog than of a wolf, which favors the belief
of De Blainville that our dogs are the descendants of a single extinct
species. On the other hand, some authors go so far as to assert that
every chief domestic breed must have had its wild prototype. This
latter view is extremely improbable: it allows nothing for variation;
it passes over the almost monstrous character of some of the breeds;
and it almost necessarily assumes that a large number of species have
become extinct since man domesticated the dog; whereas we plainly see
that wild members of the dog-family are extirpated by human agency with
much difficulty; even so recently as 1710 the wolf existed in so small
an island as Ireland.
* * * * *
[Page 18.]
At a period between four and five thousand years ago, various
breeds--viz., pariah dogs, greyhounds, common hounds, mastiffs,
house-dogs, lap-dogs, and turnspits--existed, more or less closely
resembling our present breeds. But there is not sufficient evidence
that any of these ancient dogs belonged to the same identical
sub-varieties with our present dogs. As long as man was believed to
have existed on this earth only about six thousand years, this fact of
the great diversity of the breeds at so early a period was an argument
of much weight that they had proceeded from several wild sources, for
there would not have been sufficient time for their divergence and
modification. But now that we know, from the discovery of flint tools
imbedded with the remains of extinct animals, in districts which have
since undergone great geographical changes, that man has existed for an
incomparably longer period, and bearing in mind that the most barbarous
nations possess domestic dogs, the argument from insufficient time
falls away greatly in value.
[Page 26.]
From this resemblance of the half-domesticated dogs in several
countries to the wild species still living there--from the facility
with which they can often be crossed together--from even half-tamed
animals being so much valued by savages--and from the other
circumstances previously remarked on which favor their domestication,
it is highly probable that the domestic dogs of the world are descended
from two well-defined species of wolf (viz., _C. lupus_ and _C.
latrans_), and from two or three other doubtful species (namely, the
European, Indian, and North African wolves); from at least one or two
South American canine species; from several races or species of jackal;
and perhaps from one or more extinct species.
ORIGIN OF THE HORSE.
[Animals and
Plants under
Domestication,
vol. i,
page 51.]
The history of the horse is lost in antiquity. Remains of this
animal in a domesticated condition have been found in the Swiss
lake-dwellings, belonging to the Neolithic period. At the present
time the number of breeds is great, as may be seen by consulting any
treatise on the horse. Looking only to the native ponies of Great
Britain, those of the Shetland Isles, Wales, the New Forest, and
Devonshire are distinguishable; and so it is, among other instances,
with each separate island in the great Malay Archipelago. Some of the
breeds present great differences in size, shape of ears, length of
mane, proportions of the body, form of the withers and hind-quarters,
and especially in the head. Compare the race-horse, dray-horse, and a
Shetland pony in size, configuration, and disposition; and see how much
greater the difference is than between the seven or eight other living
species of the genus _Equus_.
* * * * *
[Page 52.]
Horses have often been observed, according to M. Gaudry, to possess
a trapezium and a rudiment of a fifth metacarpal bone, so that “one
sees appearing by monstrosity, in the foot of the horse, structures
which normally exist in the foot of the hipparion”--an allied and
extinct animal. In various countries horn-like projections have been
observed on the frontal bones of the horse: in one case described by
Mr. Percival they arose about two inches above the orbital processes,
and were “very like those in a calf from five to six months old,” being
from half to three quarters of an inch in length.
CAUSES OF MODIFICATIONS IN THE HORSE.
[Page 54.]
With respect to the causes of the modifications which horses have
undergone, the conditions of life seem to produce a considerable direct
effect. Mr. D. Forbes, who has had excellent opportunities of comparing
the horses of Spain with those of South America, informs me that the
horses of Chili, which have lived under nearly the same conditions as
their progenitors in Andalusia, remain unaltered, while the Pampas
horses and the Puno ponies are considerably modified. There can be
no doubt that horses become greatly reduced in size and altered in
appearance by living on mountains and islands; and this apparently is
due to want of nutritious or varied food. Every one knows how small and
rugged the ponies are on the northern islands and on the mountains of
Europe. Corsica and Sardinia have their native ponies; and there were,
or still are, on some islands on the coast of Virginia, ponies like
those of the Shetland Islands, which are believed to have originated
through exposure to unfavorable conditions. The Puno ponies, which
inhabit the lofty regions of the Cordillera, are, as I hear from
Mr. D. Forbes, strange little creatures, very unlike their Spanish
progenitors. Farther south, in the Falkland Islands, the offspring of
the horses imported in 1764 have already so much deteriorated in size
and strength, that they are unfitted for catching wild cattle with the
lasso; so that fresh horses have to be brought for this purpose from
La Plata at a great expense. The reduced size of the horses bred on
both southern and northern islands, and on several mountain-chains,
can hardly have been caused by the cold, as a similar reduction has
occurred on the Virginian and Mediterranean islands.
* * * * *
[Page 56.]
It is scarcely possible to doubt that the long-continued selection of
qualities serviceable to man has been the chief agent in the formation
of the several breeds of the horse. Look at a dray-horse, and see how
well adapted he is to draw heavy weights, and how unlike in appearance
to any allied wild animal. The English race-horse is known to be
derived from the commingled blood of Arabs, Turks, and Barbs; but
selection, which was carried on during very early times in England,
together with training, have made him a very different animal from his
parent stocks.
“MAKING THE WORKS OF GOD A MERE MOCKERY.”
[Origin of
Species,
page 130.]
We see several distinct species of the horse-genus becoming, by
simple variation, striped on the legs like a zebra, or striped on
the shoulders like an ass. In the horse we see this tendency strong
whenever a dun tint appears--a tint that approaches to that of the
general coloring of the other species of the genus. The appearance of
the stripes is not accompanied by any change of form or by any other
new character. We see this tendency to become striped most strongly
displayed in hybrids from between several of the most distinct
species. Now observe the case of the several breeds of pigeons: they
are descended from a pigeon (including two or three sub-species or
geographical races) of a bluish color, with certain bars and other
marks; and, when any breed assumes by simple variation a bluish tint,
these bars and other marks invariably reappear; but without any other
change of form or character. When the oldest and truest breeds of
various colors are crossed, we see a strong tendency for the blue tint
and bars and marks to reappear in the mongrels. I have stated that
the most probable hypothesis to account for the reappearance of very
ancient characters is--that there is a _tendency_ in the young of each
successive generation to produce the long-lost character, and that this
tendency, from unknown causes, sometimes prevails. And we have just
seen that in several species of the horse-genus the stripes are either
plainer or appear more commonly in the young than in the old. Call the
breeds of pigeons, some of which have bred true for centuries, species;
and how exactly parallel is the case with that of the species of the
horse-genus! For myself, I venture confidently to look back thousands
on thousands of generations, and I see an animal striped like a zebra,
but perhaps otherwise very differently constructed, the common parent
of our domestic horse (whether or not it be descended from one or more
wild stocks), of the ass, the hemionus, quagga, and zebra.
He who believes that each equine species was independently created,
will, I presume, assert that each species has been created with a
tendency to vary, both under nature and under domestication, in this
particular manner, so as often to become striped like the other species
of the genus; and that each has been created with a strong tendency,
when crossed with species inhabiting distant quarters of the world, to
produce hybrids resembling in their stripes, not their own parents,
but other species of the genus. To admit this view is, as it seems to
me, to reject a real for an unreal, or at least for an unknown, cause.
It makes the works of God a mere mockery and deception; I would almost
as soon believe with the old and ignorant cosmogonists, that fossil
shells had never lived, but had been created in stone so as to mock the
shells living on the sea-shore.
VARIABILITY OF CULTIVATED PLANTS.
[Animals and
Plants, vol.
i, page 322.]
I shall not enter into so much detail on the variability of cultivated
plants as in the case of domesticated animals. The subject is
involved in much difficulty. Botanists have generally neglected
cultivated varieties, as beneath their notice. In several cases the
wild prototype is unknown or doubtfully known; and in other cases
it is hardly possible to distinguish between escaped seedlings and
truly wild plants, so that there is no safe standard of comparison by
which to judge of any supposed amount of change. Not a few botanists
believe that several of our anciently cultivated plants have become
so profoundly modified that it is not possible now to recognize their
aboriginal parent-forms. Equally perplexing are the doubts whether some
of them are descended from one species, or from several inextricably
commingled by crossing and variation. Variations often pass into, and
can not be distinguished from, monstrosities; and monstrosities are
of little significance for our purpose. Many varieties are propagated
solely by grafts, buds, layers, bulbs, etc., and frequently it is
not known how far their peculiarities can be transmitted by seminal
generation.
* * * * *
[Page 325.]
From innumerable experiments made through dire necessity by the
savages of every land, with the results handed down by tradition,
the nutritious, stimulating, and medicinal properties of the most
unpromising plants were probably first discovered. It appears, for
instance, at first an inexplicable fact that untutored man, in three
distant quarters of the world, should have discovered, among a host
of native plants, that the leaves of the tea-plant and mattee, and
the berries of the coffee, all included a stimulating and nutritious
essence, now known to be chemically the same. We can also see that
savages suffering from severe constipation would naturally observe
whether any of the roots which they devoured acted as aperients. We
probably owe our knowledge of the uses of almost all plants to man
having originally existed in a barbarous state, and having been often
compelled by severe want to try as food almost everything which he
could chew and swallow.
SAVAGE WISDOM IN THE CULTIVATION OF PLANTS.
[Page 326.]
The savage inhabitants of each land, having found out by many and
hard trials what plants were useful, or could be rendered useful by
various cooking processes, would after a time take the first step in
cultivation by planting them near their usual abodes. Livingstone
states that the savage Batokas sometimes left wild fruit-trees standing
in their gardens, and occasionally even planted them, “a practice
seen nowhere else among the natives.” But Du Chaillu saw a palm and
some other wild fruit-trees which had been planted; and these trees
were considered private property. The next step in cultivation, and
this would require but little forethought, would be to sow the seeds
of useful plants; and, as the soil near the hovels of the natives
would often be in some degree manured, improved varieties would sooner
or later arise. Or a wild and unusually good variety of a native
plant might attract the attention of some wise old savage; and he
would transplant it, or sow its seed. That superior varieties of wild
fruit-trees occasionally are found is certain, as in the case of the
American species of hawthorns, plums, cherries, grapes, and hickories,
specified by Professor Asa Gray.
* * * * *
[Page 336.]
We now know that man was sufficiently civilized to cultivate the ground
at an immensely remote period; so that wheat might have been improved
long ago up to that standard of excellence which was possible under the
then existing state of agriculture. One small class of facts supports
this view of the slow and gradual improvement of our cereals. In the
most ancient lake-habitations of Switzerland, when men employed only
flint-tools, the most extensively cultivated wheat was a peculiar kind,
with remarkably small ears and grains. “While the grains of the modern
forms are in section from seven to eight millimetres in length, the
larger grains from the lake-habitations are six, seldom seven, and
the smaller ones only four. The ear is thus much narrower, and the
spikelets stand out more horizontally, than in our present forms.” So
again with barley, the most ancient and most extensively cultivated
kind had small ears, and the grains were “smaller, shorter, and nearer
to each other, than in that now grown; without the husk they were two
and one half lines long, and scarcely one and one half broad, while
those now grown have a length of three lines, and almost the same
in breadth.” These small-grained varieties of wheat and barley are
believed by Heer to be the parent-forms of certain existing allied
varieties, which have supplanted their early progenitors.
UNKNOWN LAWS OF INHERITANCE.
[Origin of
Species,
page 10.]
The laws governing inheritance are for the most part unknown. No one
can say why the same peculiarity in different individuals of the same
species, or in different species, is sometimes inherited and sometimes
not so; why the child often reverts in certain characters to its
grandfather or grandmother or more remote ancestor; why a peculiarity
is often transmitted from one sex to both sexes, or to one sex alone,
more commonly but not exclusively to the like sex. It is a fact of
some importance to us that peculiarities appearing in the males of our
domestic breeds are often transmitted either exclusively, or in a much
greater degree, to the males alone. A much more important rule, which I
think may be trusted, is that, at whatever period of life a peculiarity
first appears, it tends to reappear in the offspring at a corresponding
age, though sometimes earlier. In many cases this could not be
otherwise: thus the inherited peculiarities in the horns of cattle
could appear only in the offspring when nearly mature; peculiarities
in the silk-worm are known to appear at the corresponding caterpillar
or cocoon stage. But hereditary diseases and some other facts make me
believe that the rule has a wider extension, and that, when there is no
apparent reason why a peculiarity should appear at any particular age,
yet that it does tend to appear in the offspring at the same period at
which it first appeared in the parent. I believe this rule to be of the
highest importance in explaining the laws of embryology. These remarks
are, of course, confined to the first _appearance_ of the peculiarity,
and not to the primary cause which may have acted on the ovules or on
the male element; in nearly the same manner as the increased length of
the horns in the offspring from a short-horned cow by a long-horned
bull, though appearing late in life, is clearly due to the male element.
* * * * *
[Variation of
Animals and
Plants, vol.
i, page 445.]
If animals and plants had never been domesticated, and wild ones alone
had been observed, we should probably never have heard the saying that
“like begets like.” The proposition would have been as self-evident
as that all the buds on the same tree are alike, though neither
proposition is strictly true. For, as has often been remarked, probably
no two individuals are identically the same. All wild animals recognize
each other, which shows that there is some difference between them;
and, when the eye is well practiced, the shepherd knows each sheep, and
man can distinguish a fellow-man out of millions on millions of other
men.
* * * * *
[Page 446.]
The subject of inheritance is wonderful. When a new character arises,
whatever its nature may be, it generally tends to be inherited, at
least in a temporary and sometimes in a most persistent manner.
What can be more wonderful than that some trifling peculiarity, not
primordially attached to the species, should be transmitted through the
male or female sexual cells, which are so minute as not to be visible
to the naked eye, and afterward through the incessant changes of a long
course of development, undergone either in the womb or in the egg, and
ultimately appear in the offspring when mature, or even when quite
old, as in the case of certain diseases? Or, again, what can be more
wonderful than the well-ascertained fact that the minute ovule of a
good milking-cow will produce a male, from whom a cell, in union with
an ovule, will produce a female, and she, when mature, will have large
mammary glands, yielding an abundant supply of milk, and even milk of
a particular quality? Nevertheless, the real subject of surprise is,
as Sir H. Holland has well remarked, not that a character should be
inherited, but that any should ever fail to be inherited.
LAWS OF INHERITANCE THAT ARE FAIRLY WELL ESTABLISHED.
[Animals and
Plants, vol.
ii, page 61.]
Though much remains obscure with respect to inheritance, we may look
at the following laws as fairly well established: Firstly, a tendency
in every character, new and old, to be transmitted by seminal and bud
generation, though often counteracted by various known and unknown
causes. Secondly, reversion or atavism, which depends on transmission
and development being distinct powers: it acts in various degrees and
manners through both seminal and bud generation. Thirdly, prepotency of
transmission, which may be confined to one sex, or be common to both
sexes. Fourthly, transmission, as limited by sex, generally to the same
sex in which the inherited character first appeared; and this in many,
probably most cases, depends on the new character having first appeared
at a rather late period of life. Fifthly, inheritance at corresponding
periods of life, with some tendency to the earlier development of the
inherited character. In these laws of inheritance, as displayed under
domestication, we see an ample provision for the production, through
variability and natural selection, of new specific forms.
INHERITED PECULIARITIES IN MAN.
[Animals and
Plants, vol.
i, page 450.]
Gait, gestures, voice, and general bearing, are all inherited, as
the illustrious Hunter and Sir A. Carlisle have insisted. My father
communicated to me some striking instances, in one of which a man died
during the early infancy of his son, and my father, who did not see
this son until grown up and out of health, declared that it seemed to
him as if his old friend had risen from the grave, with all his highly
peculiar habits and manners. Peculiar manners pass into tricks, and
several instances could be given of their inheritance; as in the case,
often quoted, of the father who generally slept on his back, with his
right leg crossed over the left, and whose daughter, while an infant in
the cradle, followed exactly the same habit, though an attempt was made
to cure her. I will give one instance which has fallen under my own
observation, and which is curious from being a trick associated with
a peculiar state of mind, namely, pleasurable emotion. A boy had the
singular habit, when pleased, of rapidly moving his fingers parallel
to each other, and, when much excited, of raising both hands, with the
fingers still moving, to the sides of his face on a level with the
eyes: when this boy was almost an old man, he could still hardly resist
this trick when much pleased, but from its absurdity concealed it. He
had eight children. Of these, a girl, when pleased, at the age of four
and a half years, moved her fingers in exactly the same way, and, what
is still odder, when much excited, she raised both her hands, with her
fingers still moving, to the sides of her face, in exactly the same
manner as her father had done, and sometimes even still continued to do
so when alone. I never heard of any one, excepting this one man and his
little daughter, who had this strange habit; and certainly imitation
was in this instance out of the question.
INHERITED DISEASES.
[Animals and
Plants, vol.
ii, page 54.]
Large classes of diseases usually appear at certain ages, such as St.
Vitus’s dance in youth, consumption in early mid-life, gout later,
and apoplexy still later; and these are naturally inherited at the
same period. But, even in diseases of this class, instances have been
recorded, as with St. Vitus’s dance, showing that an unusually early
or late tendency to the disease is inheritable. In most cases the
appearance of any inherited disease is largely determined by certain
critical periods in each person’s life, as well as by unfavorable
conditions. There are many other diseases, which are not attached to
any particular period, but which certainly tend to appear in the child
at about the same age at which the parent was first attacked. An array
of high authorities, ancient and modern, could be given in support of
this proposition. The illustrious Hunter believed in it; and Piorry
cautions the physician to look closely to the child at the period when
any grave inheritable disease attacked the parent. Dr. Prosper Lucas,
after collecting facts from every source, asserts that affections of
all kinds, though not related to any particular period of life, tend
to reappear in the offspring at whatever period of life they first
appeared in the progenitor.
* * * * *
[Page 55.]
Esquirol gives several striking instances of insanity coming on at
the same age as that of a grandfather, father, and son, who all
committed suicide near their fiftieth year. Many other cases could
be given, as of a whole family who became insane at the age of
forty. Other cerebral affections sometimes follow the same rule--for
instance, epilepsy and apoplexy. A woman died of the latter disease
when sixty-three years old; one of her daughters at forty-three, and
the other at sixty-seven: the latter had twelve children, who all
died from tubercular meningitis. I mention this latter case because
it illustrates a frequent occurrence, namely, a change in the precise
nature of an inherited disease, though still affecting the same organ.
* * * * *
Two brothers, their father, their paternal uncles, seven cousins,
and their paternal grandfather, were all similarly affected by a
skin-disease, called pityriasis versicolor; “the disease, strictly
limited to the males of the family (though transmitted through the
females), usually appeared at puberty, and disappeared at about the
age of forty or forty-five years.” The second case is that of four
brothers, who, when about twelve years old, suffered almost every week
from severe headaches, which were relieved only by a recumbent position
in a dark room. Their father, paternal uncles, paternal grandfather,
and grand-uncles all suffered in the same way from headaches, which
ceased at the age of fifty-four or fifty-five in all those who lived so
long. None of the females of the family were affected.
CAUSES OF NON-INHERITANCE.
[Animals and
Plants, vol.
i, page 470.]
A large number of cases of non-inheritance are intelligible on the
principle that a strong tendency to inheritance does exist, but that it
is overborne by hostile or unfavorable conditions of life. No one would
expect that our improved pigs, if forced during several generations
to travel about and root in the ground for their own subsistence,
would transmit, as truly as they now do, their short muzzles and legs,
and their tendency to fatten. Dray-horses assuredly would not long
transmit their great size and massive limbs, if compelled to live
in a cold, damp, mountainous region; we have, indeed, evidence of
such deterioration in the horses which have run wild on the Falkland
Islands. European dogs in India often fail to transmit their true
character. Our sheep in tropical countries lose their wool in a few
generations. There seems also to be a close relation between certain
peculiar pastures and the inheritance of an enlarged tail in fat-tailed
sheep, which form one of the most ancient breeds in the world. With
plants, we have seen that tropical varieties of maize lose their proper
character in the course of two or three generations, when cultivated
in Europe; and conversely so it is with European varieties cultivated
in Brazil. Our cabbages, which here come so true by seed, can not form
heads in hot countries. According to Carrière, the purple-leafed beech
and barberry transmit their character by seed far less truly in certain
districts than in others. Under changed circumstances, periodical
habits of life soon fail to be transmitted, as the period of maturity
in summer and winter wheat, barley, and vetches. So it is with animals:
for instance, a person, whose statement I can trust, procured eggs of
Aylesbury ducks from that town, where they are kept in houses, and are
reared as early as possible for the London market; the ducks bred from
these eggs in a distant part of England, hatched their first brood on
January 24th, while common ducks, kept in the same yard and treated in
the same manner, did not hatch till the end of March; and this shows
that the period of hatching was inherited. But the grandchildren of
these Aylesbury ducks completely lost their habit of early incubation,
and hatched their eggs at the same time with the common ducks of the
same place.
Many cases of non-inheritance apparently result from the conditions of
life continually inducing fresh variability. We have seen that when the
seeds of pears, plums, apples, etc., are sown, the seedlings generally
inherit some degree of family likeness. Mingled with these seedlings,
a few, and sometimes many, worthless, wild-looking plants commonly
appear, and their appearance may be attributed to the principle of
reversion. But scarcely a single seedling will be found perfectly to
resemble the parent-form; and this may be accounted for by constantly
recurring variability induced by the conditions of life.
STEPS BY WHICH DOMESTIC RACES HAVE BEEN PRODUCED.
[Origin of
Species,
page 22.]
Some effect may be attributed to the direct and definite action of the
external conditions of life, and some to habit; but he would be a bold
man who would account by such agencies for the differences between a
dray and race horse, a greyhound and blood-hound, a carrier and tumbler
pigeon. One of the most remarkable features in our domesticated races
is that we see in them adaptation, not, indeed, to the animal’s or
plant’s own good, but to man’s use or fancy. Some variations useful to
him have probably arisen suddenly, or by one step; many botanists, for
instance, believe that the fuller’s teasel, with its hooks, which can
not be rivaled by any mechanical contrivance, is only a variety of the
wild _Dipsacus_; and this amount of change may have suddenly arisen in
a seedling. So it has probably been with the turnspit-dog; and this is
known to have been the case with the ancon sheep. But when we compare
the dray-horse and race-horse, the dromedary and camel, the various
breeds of sheep fitted either for cultivated land or mountain-pasture,
with the wool of one breed good for one purpose, and that of another
breed for another purpose; when we compare the many breeds of dogs,
each good for man in different ways; when we compare the game-cock, so
pertinacious in battle, with other breeds so little quarrelsome, with
“everlasting layers” which never desire to sit, and with the bantam, so
small and elegant; when we compare the host of agricultural, culinary,
orchard, and flower-garden races of plants, most useful to man at
different seasons and for different purposes, or so beautiful in his
eyes--we must, I think, look further than to mere variability. We can
not suppose that all the breeds were suddenly produced as perfect and
as useful as we now see them; indeed, in many cases, we know that this
has not been their history. The key is man’s power of accumulative
selection: Nature gives successive variations; man adds them up in
certain directions useful to him. In this sense he may be said to have
made for himself useful breeds.
* * * * *
[Page 23.]
If selection consisted merely in separating some very distinct variety,
and breeding from it, the principle would be so obvious as hardly to be
worth notice; but its importance consists in the great effect produced
by the accumulation in one direction, during successive generations, of
differences absolutely inappreciable by an uneducated eye--differences
which I for one have vainly attempted to appreciate. Not one man in
a thousand has accuracy of eye and judgment sufficient to become an
eminent breeder. If gifted with these qualities, and he studies his
subject for years, and devotes his lifetime to it with indomitable
perseverance, he will succeed, and may make great improvements; if
he wants any of these qualities, he will assuredly fail. Few would
readily believe in the natural capacity and years of practice requisite
to become even a skillful pigeon-fancier.
UNCONSCIOUS SELECTION.
[Origin of
Species,
page 25.]
A man who intends keeping pointers naturally tries to get as good dogs
as he can, and afterward breeds from his own best dogs, but he has no
wish or expectation of permanently altering the breed. Nevertheless,
we may infer that this process, continued during centuries, would
improve and modify any breed, in the same way as Bakewell, Collins,
etc., by this very same process, only carried on more methodically, did
greatly modify, even during their lifetimes, the forms and qualities
of their cattle. Slow and insensible changes of this kind can never be
recognized unless actual measurements or careful drawings of the breeds
in question have been made long ago, which may serve for comparison.
In some cases, however, unchanged or but little changed individuals
of the same breed exist in less civilized districts, where the breed
has been less improved. There is reason to believe that King Charles’s
spaniel has been unconsciously modified to a large extent since the
time of that monarch. Some highly competent authorities are convinced
that the setter is directly derived from the spaniel, and has probably
been slowly altered from it. It is known that the English pointer has
been greatly changed within the last century, and in this case the
change has, it is believed, been chiefly effected by crosses with the
fox-hound; but what concerns us is, that the change has been effected
unconsciously and gradually, and yet so effectually, that, though the
old Spanish pointer certainly came from Spain, Mr. Borrow has not
seen, as I am informed by him, any native dog in Spain like our pointer.
By a similar process of selection, and by careful training, English
race-horses have come to surpass in fleetness and size the parent
Arabs, so that the latter, by the regulations for the Goodwood races,
are favored in the weights which they carry. Lord Spencer and others
have shown how the cattle of England have increased in weight and in
early maturity, compared with the stock formerly kept in this country.
* * * * *
[Page 26.]
If there exist savages so barbarous as never to think of the inherited
character of the offspring of their domestic animals, yet any one
animal particularly useful to them, for any special purpose, would
be carefully preserved during famines and other accidents, to which
savages are so liable, and such choice animals would thus generally
leave more offspring than the inferior ones; so that in this case there
would be a kind of unconscious selection going on. We see the value set
on animals even by the barbarians of Tierra del Fuego, by their killing
and devouring their old women, in times of dearth, as of less value
than their dogs.
ADAPTATION OF ANIMALS TO THE FANCIES OF MAN.
[Page 28.]
On the view here given of the important part which selection by man has
played, it becomes at once obvious how it is that our domestic races
show adaptation in their structure or in their habits to man’s wants or
fancies. We can, I think, further understand the frequently abnormal
character of our domestic races, and likewise their differences being
so great in external characters, and relatively so slight in internal
parts or organs. Man can hardly select, or only with much difficulty,
any deviation of structure excepting such as is externally visible;
and, indeed, he rarely cares for what is internal. He can never act
by selection, excepting on variations which are first given to him in
some slight degree by nature. No man would ever try to make a fantail
till he saw a pigeon with a tail developed in some slight degree in
an unusual manner, or a pouter till he saw a pigeon with a crop of
somewhat unusual size; and the more abnormal or unusual any character
was when it first appeared, the more likely it would be to catch his
attention. But to use such an expression as trying to make a fantail
is, I have no doubt, in most cases, utterly incorrect. The man who
first selected a pigeon with a slightly larger tail, never dreamed what
the descendants of that pigeon would become through long-continued,
partly unconscious and partly methodical, selection. Perhaps the
parent-bird of all fantails had only fourteen tail-feathers somewhat
expanded, like the present Java fantail, or like individuals of other
and distinct breeds, in which as many as seventeen tail-feathers have
been counted. Perhaps the first pouter-pigeon did not inflate its crop
much more than the turbit now does the upper part of its œsophagus--a
habit which is disregarded by all fanciers, as it is not one of the
points of the breed.
DOUBTFUL SPECIES.
[Origin of
Species,
page 36.]
The forms which possess in some considerable degree the character of
species, but which are so closely similar to other forms, or are so
closely linked to them by intermediate gradations, that naturalists
do not like to rank them as distinct species, are in several respects
the most important for us. We have every reason to believe that many
of these doubtful and closely allied forms have permanently retained
their characters for a long time; for as long, as far as we know, as
have good and true species. Practically, when a naturalist can unite
by means of intermediate links any two forms, he treats the one as a
variety of the other; ranking the most common, but sometimes the one
first described, as the species, and the other as the variety. But
cases of great difficulty, which I will not here enumerate, sometimes
arise in deciding whether or not to rank one form as a variety of
another, even when they are closely connected by intermediate links;
nor will the commonly-assumed hybrid nature of the intermediate forms
always remove the difficulty. In very many cases, however, one form is
ranked as a variety of another, not because the intermediate links have
actually been found, but because analogy leads the observer to suppose
either that they do now somewhere exist, or may formerly have existed;
and here a wide door for the entry of doubt and conjecture is opened.
Hence, in determining whether a form should be ranked as a species or
a variety, the opinion of naturalists having sound judgment and wide
experience seems the only guide to follow. We must, however, in many
cases, decide by a majority of naturalists, for few well-marked and
well-known varieties can be named which have not been ranked as species
by at least some competent judges.
That varieties of this doubtful nature are far from uncommon can not
be disputed. Compare the several floras of Great Britain, of France,
or of the United States, drawn up by different botanists, and see what
a surprising number of forms have been ranked by one botanist as good
species, and by another as mere varieties. Mr. H. C. Watson, to whom
I lie under deep obligation for assistance of all kinds, has marked
for me one hundred and eighty-two British plants, which are generally
considered as varieties, but which have all been ranked by botanists
as species; and in making this list he has omitted many trifling
varieties, but which nevertheless have been ranked by some botanists as
species, and he has entirely omitted several highly polymorphic genera.
Under genera, including the most polymorphic forms, Mr. Babington gives
two hundred and fifty-one species, whereas Mr. Bentham gives only
one hundred and twelve--a difference of one hundred and thirty-nine
doubtful forms!
SPECIES AN ARBITRARY TERM.
[Page 41.]
Certainly no clear line of demarkation has as yet been drawn between
species and sub-species--that is, the forms which in the opinion
of some naturalists come very near to, but do not quite arrive at,
the rank of species; or, again, between sub-species and well-marked
varieties, or between lesser varieties and individual differences.
These differences blend into each other by an insensible series; and a
series impresses the mind with the idea of an actual passage.
Hence I look at individual differences, though of small interest to
the systematist, as of the highest importance for us, as being the
first steps toward such slight varieties as are barely thought worth
recording in works on natural history. And I look at varieties which
are in any degree more distinct and permanent as steps toward more
strongly-marked and permanent varieties; and at the latter, as leading
to sub-species, and then to species. The passage from one stage of
difference to another may, in many cases, be the simple result of the
nature of the organism, and of the different physical conditions to
which it has long been exposed; but with respect to the more important
and adaptive characters, the passage from one stage of difference to
another may be safely attributed to the cumulative action of natural
selection, hereafter to be explained, and to the effects of the
increased use or disuse of parts. A well-marked variety may therefore
be called an incipient species; but whether this belief is justifiable
must be judged by the weight of the various facts and considerations to
be given throughout this work.
It need not be supposed that all varieties or incipient species attain
the rank of species. They may become extinct, or they may endure as
varieties for very long periods, as has been shown to be the case by
Mr. Wollaston with the varieties of certain fossil land-shells in
Madeira, and with plants by Gaston de Saporta. If a variety were to
flourish so as to exceed in numbers the parent species, it would then
rank as the species, and the species as the variety; or it might come
to supplant and exterminate the parent species; or both might coexist,
and both rank as independent species. But we shall hereafter return to
this subject.
From these remarks it will be seen that I look at the term species
as one arbitrarily given, for the sake of convenience, to a set
of individuals closely resembling each other, and that it does
not essentially differ from the term variety, which is given to
less distinct and more fluctuating forms. The term variety, again,
in comparison with mere individual differences, is also applied
arbitrarily, for convenience’ sake.
THE TRUE PLAN OF CREATION.
[Origin of
Species,
page 425.]
When the views advanced by me in this volume, and by Mr. Wallace, or
when analogous views on the origin of species are generally admitted,
we can dimly foresee that there will be a considerable revolution in
natural history. Systematists will be able to pursue their labors as at
present; but they will not be incessantly haunted by the shadowy doubt
whether this or that form be a true species.
* * * * *
[Page 426.]
Hereafter we shall be compelled to acknowledge that the only
distinction between species and well-marked varieties is, that the
latter are known, or believed, to be connected at the present day by
intermediate gradations, whereas species were formerly thus connected.
Hence, without rejecting the consideration of the present existence
of intermediate gradations between any two forms, we shall be led
to weigh more carefully and to value higher the actual amount of
difference between them. It is quite possible that forms now generally
acknowledged to be merely varieties may hereafter be thought worthy of
specific names; and in this case scientific and common language will
come into accordance. In short, we shall have to treat species in the
same manner as those naturalists treat genera who admit that genera are
merely artificial combinations made for convenience. This may not be a
cheering prospect; but we shall at least be freed from the vain search
for the undiscovered and undiscoverable essence of the term species.
The other and more general departments of natural history will rise
greatly in interest. The terms used by naturalists, of affinity,
relationship, community of type, paternity, morphology, adaptive
characters, rudimentary and aborted organs, etc., will cease to be
metaphorical, and will have a plain signification. When we no longer
look at an organic being as a savage looks at a ship, as something
wholly beyond his comprehension; when we regard every production of
nature as one which has had a long history; when we contemplate every
complex structure and instinct as the summing up of many contrivances,
each useful to the possessor, in the same way as any great mechanical
invention is the summing up of the labor, the experience, the reason,
and even the blunders of numerous workmen; when we thus view each
organic being, how far more interesting--I speak from experience--does
the study of natural history become!
A grand and almost untrodden field of inquiry will be opened, on the
causes and laws of variation, on correlation, on the effects of use
and disuse, on the direct action of external conditions, and so forth.
The study of domestic productions will rise immensely in value. A new
variety raised by man will be a more important and interesting subject
for study than one more species added to the infinitude of already
recorded species. Our classifications will come to be, as far as they
can be so made, genealogies, and will then truly give what may be
called the plan of creation.
IV.
THE STRUGGLE FOR EXISTENCE.
[Origin of
Species,
page 50.]
A struggle for existence inevitably follows from the high rate at
which all organic beings tend to increase. Every being, which during
its natural lifetime produces several eggs or seeds, must suffer
destruction during some period of its life, and during some season or
occasional year, otherwise, on the principle of geometrical increase,
its numbers would quickly become so inordinately great that no country
could support the product. Hence, as more individuals are produced
than can possibly survive, there must in every case be a struggle for
existence, either one individual with another of the same species,
or with the individuals of distinct species, or with the physical
conditions of life. It is the doctrine of Malthus applied with
manifold force to the whole animal and vegetable kingdoms; for in this
case there can be no artificial increase of food, and no prudential
restraint from marriage. Although some species may be now increasing,
more or less rapidly, in numbers, all can not do so, for the world
would not hold them.
There is no exception to the rule that every organic being naturally
increases at so high a rate, that, if not destroyed, the earth would
soon be covered with the progeny of a single pair. Even slow-breeding
man has doubled in twenty-five years, and at this rate, in less than
a thousand years, there would literally not be standing-room for his
progeny. Linnæus has calculated that if an annual plant produced only
two seeds--and there is no plant so unproductive as this--and their
seedlings next year produced two, and so on, then in twenty years there
would be a million plants. The elephant is reckoned the slowest breeder
of all known animals, and I have taken some pains to estimate its
probable minimum rate of natural increase; it will be safest to assume
that it begins breeding when thirty years old, and goes on breeding
till ninety years old, bringing forth six young in the interval, and
surviving till one hundred years old; if this be so, after a period of
from seven hundred and forty to seven hundred and fifty years, there
would be nearly nineteen million elephants alive, descended from the
first pair.
DEATH INEVITABLE IN THE FIGHT FOR LIFE.
[Page 52.]
In a state of nature almost every full-grown plant annually produces
seed, and among animals there are very few which do not annually pair.
Hence we may confidently assert that all plants and animals are tending
to increase at a geometrical ratio, that all would rapidly stock every
station in which they could anyhow exist, and that this geometrical
tendency to increase must be checked by destruction at some period of
life. Our familiarity with the larger domestic animals tends, I think,
to mislead us: we see no great destruction falling on them, but we do
not keep in mind that thousands are annually slaughtered for food, and
that in a state of nature an equal number would have somehow to be
disposed of.
The only difference between organisms which annually produce eggs or
seeds by the thousand and those which produce extremely few is, that
the slow breeders would require a few more years to people, under
favorable conditions, a whole district, let it be ever so large. The
condor lays a couple of eggs and the ostrich a score, and yet in the
same country the condor may be the more numerous of the two; the Fulmar
petrel lays but one egg, yet it is believed to be the most numerous
bird in the world. One fly deposits hundreds of eggs, and another, like
the _Hippobosca_, a single one; but this difference does not determine
how many individuals of the two species can be supported in a district.
A large number of eggs is of some importance to those species which
depend on a fluctuating amount of food, for it allows them rapidly to
increase in number. But the real importance of a large number of eggs
or seeds is to make up for much destruction at some period of life;
and this period in the great majority of cases is an early one. If an
animal can in any way protect its own eggs or young, a small number may
be produced, and yet the average stock be fully kept up; but, if many
eggs or young are destroyed, many must be produced, or the species will
become extinct. It would suffice to keep up the full number of a tree,
which lived on an average for a thousand years, if a single seed were
produced once in a thousand years, supposing that this seed were never
destroyed, and could be insured to germinate in a fitting place. So
that, in all cases, the average number of any animal or plant depends
only indirectly on the number of its eggs or seeds.
In looking at Nature, it is most necessary to keep the foregoing
considerations always in mind--never to forget that every single
organic being may be said to be striving to the utmost to increase in
numbers; that each lives by a struggle at some period of its life;
that heavy destruction inevitably falls either on the young or old
during each generation or at recurrent intervals. Lighten any check,
mitigate the destruction ever so little, and the number of the species
will almost instantaneously increase to any amount.
“INEXPLICABLE ON THE THEORY OF CREATION.”
[Origin of
Species,
page 413.]
As each species tends by its geometrical rate of reproduction to
increase inordinately in number, and as the modified descendants of
each species will be enabled to increase by as much as they become more
diversified in habits and structure, so as to be able to seize on many
and widely different places in the economy of nature, there will be a
constant tendency in natural selection to preserve the most divergent
offspring of any one species. Hence, during a long-continued course
of modification, the slight differences characteristic of varieties
of the same species tend to be augmented into the greater differences
characteristic of the species of the same genus. New and improved
varieties will inevitably supplant and exterminate the older, less
improved, and intermediate varieties; and thus species are rendered
to a large extent defined and distinct objects. Dominant species
belonging to the larger groups within each class tend to give birth
to new and dominant forms; so that each large group tends to become
still larger, and at the same time more divergent in character. But,
as all groups can not thus go on increasing in size, for the world
would not hold them, the more dominant groups beat the less dominant.
This tendency in the large groups to go on increasing in size and
diverging in character, together with the inevitable contingency of
much extinction, explains the arrangement of all the forms of life in
groups subordinate to groups, all within a few great classes, which
has prevailed throughout all time. This grand fact of the grouping of
all organic beings under what is called the Natural System is utterly
inexplicable on the theory of creation.
OBSCURE CHECKS TO INCREASE.
[Origin of
Species,
page 53.]
The causes which check the natural tendency of each species to increase
are most obscure. Look at the most vigorous species; by as much as it
swarms in numbers, by so much will it tend to increase still further.
We know not exactly what the checks are even in a single instance. Nor
will this surprise any one who reflects how ignorant we are on this
head, even in regard to mankind, although so incomparably better known
than any other animal.
* * * * *
Eggs or very young animals seem generally to suffer most, but this is
not invariably the case. With plants there is a vast destruction of
seeds, but, from some observations which I have made it appears that
the seedlings suffer most from germinating in ground already thickly
stocked with other plants. Seedlings, also, are destroyed in vast
numbers by various enemies; for instance, on a piece of ground three
feet long and two wide, dug and cleared, and where there could be no
choking from other plants, I marked all the seedlings of our native
weeds as they came up, and out of 357 no less than 295 were destroyed,
chiefly by slugs and insects. If turf which has long been mown, and the
case would be the same with turf closely browsed by quadrupeds, be let
to grow, the more vigorous plants gradually kill the less vigorous,
though fully grown plants; thus out of twenty species growing on a
little plot of mown turf (three feet by four) nine species perished,
from the other species being allowed to grow up freely.
The amount of food for each species, of course, gives the extreme limit
to which each can increase; but very frequently it is not the obtaining
food, but the serving as prey to other animals, which determines the
average number of a species. Thus, there seems to be little doubt that
the stock of partridges, grouse, and hares on any large estate depends
chiefly on the destruction of vermin. If not one head of game were shot
during the next twenty years in England, and, at the same time, if no
vermin were destroyed, there would, in all probability, be less game
than at present, although hundreds of thousands of game animals are now
annually shot. On the other hand, in some cases, as with the elephant,
none are destroyed by beasts of prey; for even the tiger in India most
rarely dares to attack a young elephant protected by its dam.
CLIMATE AS A CHECK TO INCREASE.
[Page 54.]
Climate plays an important part in determining the average numbers of
a species, and periodical seasons of extreme cold or drought seem to
be the most effective of all checks. I estimated (chiefly from the
greatly reduced numbers of nests in the spring) that the winter of
1854–’55 destroyed four fifths of the birds in my own grounds; and this
is a tremendous destruction, when we remember that ten per cent is an
extraordinarily severe mortality from epidemics with man. The action of
climate seems at first sight to be quite independent of the struggle
for existence; but, in so far as climate chiefly acts in reducing
food, it brings on the most severe struggle between the individuals,
whether of the same or of distinct species, which subsist on the same
kind of food. Even when climate--for instance, extreme cold--acts
directly, it will be the least vigorous individuals, or those which
have got least food through the advancing winter, which will suffer
most. When we travel from south to north, or from a damp region to a
dry, we invariably see some species gradually getting rarer and rarer,
and finally disappearing; and, the change of climate being conspicuous,
we are tempted to attribute the whole effect to its direct action. But
this is a false view: we forget that each species, even where it most
abounds, is constantly suffering enormous destruction at some period
of its life, from enemies or from competitors for the same place and
food; and, if these enemies or competitors be in the least degree
favored by any slight change of climate, they will increase in numbers;
and, as each area is already fully stocked with inhabitants, the other
species must decrease. When we travel southward and see a species
decreasing in numbers, we may feel sure that the cause lies quite as
much in other species being favored as in this one being hurt. So it
is when we travel northward, but in a somewhat lesser degree, for the
number of species of all kinds, and therefore of competitors, decreases
northward; hence, in going northward, or in ascending a mountain, we
far oftener meet with stunted forms, due to the _directly_ injurious
action of climate, than we do in proceeding southward or in descending
a mountain. When we reach the Arctic regions, or snow-capped summits,
or absolute deserts, the struggle for life is almost exclusively with
the elements.
INFLUENCE OF INSECTS IN THE STRUGGLE FOR EXISTENCE.
[Page 56.]
In several parts of the world insects determine the existence of
cattle. Perhaps Paraguay offers the most curious instance of this; for
here neither cattle nor horses nor dogs have ever run wild, though they
swarm southward and northward in a feral state; and Azara and Rengger
have shown that this is caused by the greater number in Paraguay of
a certain fly, which lays its eggs in the navels of these animals
when first born. The increase of these flies, numerous as they are,
must be habitually checked by some means, probably by other parasitic
insects. Hence, if certain insectivorous birds were to decrease in
Paraguay, the parasitic insects would probably increase; and this
would lessen the number of the navel-frequenting flies; then cattle
and horses would become feral, and this would certainly greatly alter
(as indeed I have observed in parts of South America) the vegetation:
this again would largely affect the insects, and this, as we have
just seen in Staffordshire, the insectivorous birds, and so onward
in ever-increasing circles of complexity. Not that under nature the
relations will ever be as simple as this. Battle within battle must be
continually recurring with varying success; and yet in the long run
the forces are so nicely balanced that the face of Nature remains for
long periods of time uniform, though assuredly the merest trifle would
give the victory to one organic being over another. Nevertheless, so
profound is our ignorance, and so high our presumption, that we marvel
when we hear of the extinction of an organic being; and, as we do not
see the cause, we invoke cataclysms to desolate the world, or invent
laws on the duration of the forms of life!
* * * * *
[Page 57.]
Nearly all our orchidaceous plants absolutely require the visits of
insects to remove their pollen-masses and thus to fertilize them. I
find from experiments that humble-bees are almost indispensable to
the fertilization of the heart’s-ease (_Viola tricolor_), for other
bees do not visit this flower. I have also found that the visits of
bees are necessary for the fertilization of some kinds of clover: for
instance, 20 heads of Dutch clover (_Trifolium repens_) yielded 2,290
seeds, but 20 other heads protected from bees produced not one. Again,
100 heads of red clover (_T. pratense_) produced 2,700 seeds, but the
same number of protected heads produced not a single seed. Humble-bees
alone visit red clover, as other bees can not reach the nectar. It
has been suggested that moths may fertilize the clovers; but I doubt
whether they could do so in the case of the red clover, from their
weight not being sufficient to depress the wing-petals. Hence we may
infer as highly probable that, if the whole genus of humble-bees became
extinct or very rare in England, the heart’s-ease and red clover would
become very rare, or wholly disappear. The number of humble-bees in
any district depends in a great measure on the number of field-mice,
which destroy their combs and nests; and Colonel Newman, who has long
attended to the habits of humble-bees, believes that “more than two
thirds of them are thus destroyed all over England.” Now, the number
of mice is largely dependent, as every one knows, on the number of
cats; and Colonel Newman says, “Near villages and small towns I have
found the nests of humble-bees more numerous than elsewhere, which I
attribute to the number of cats that destroy the mice.” Hence it is
quite credible that the presence of a feline animal in large numbers in
a district might determine, through the intervention first of mice and
then of bees, the frequency of certain flowers in that district!
NO SUCH THING AS CHANCE IN THE RESULT OF THE STRUGGLE.
[Page 58.]
When we look at the plants and bushes clothing an entangled bank, we
are tempted to attribute their proportional numbers and kinds to what
we call chance. But how false a view is this! Every one has heard
that, when an American forest is cut down, a very different vegetation
springs up; but it has been observed that ancient Indian ruins in
the Southern United States, which must formerly have been cleared of
trees, now display the same beautiful diversity and proportion of
kinds as in the surrounding virgin forest. What a struggle must have
gone on during long centuries between the several kinds of trees, each
annually scattering its seeds by the thousand; what war between insect
and insect--between insects, snails, and other animals with birds and
beasts of prey--all striving to increase, all feeding on each other, or
on the trees, their seeds and seedlings, or on the other plants which
first clothed the ground and thus checked the growth of the trees!
Throw up a handful of feathers, and all fall to the ground according
to definite laws; but how simple is the problem where each shall fall
compared to that of the action and reaction of the innumerable plants
and animals which have determined, in the course of centuries, the
proportional numbers and kinds of trees now growing on the old Indian
ruins!
* * * * *
[Page 61.]
It is good thus to try in imagination to give to any one species an
advantage over another. Probably in no single instance should we know
what to do. This ought to convince us of our ignorance on the mutual
relations of all organic beings--a conviction as necessary as it is
difficult to acquire. All that we can do is to keep steadily in mind
that each organic being is striving to increase in a geometrical ratio;
that each at some period of its life, during some season of the year,
during each generation or at intervals, has to struggle for life and
to suffer great destruction. When we reflect on this struggle, we may
console ourselves with the full belief that the war of nature is not
incessant, that no fear is felt, that death is generally prompt, and
that the vigorous, the healthy, and the happy survive and multiply.
V.
NATURAL SELECTION: OR, THE SURVIVAL OF THE FITTEST.
[Variation of
Animals and
Plants under
Domestication,
vol. i,
page 6.]
The preservation, during the battle for life, of varieties which
possess any advantage in structure, constitution, or instinct, I
have called Natural Selection; and Mr. Herbert Spencer has well
expressed the same idea by the Survival of the Fittest. The term
“natural selection” is in some respects a bad one, as it seems to
imply conscious choice; but this will be disregarded after a little
familiarity. No one objects to chemists speaking of “elective
affinity”; and certainly an acid has no more choice in combining with a
base than the conditions of life have in determining whether or not a
new form be selected or preserved. The term is so far a good one as it
brings into connection the production of domestic races by man’s power
of selection and the natural preservation of varieties and species
in a state of nature. For brevity sake I sometimes speak of natural
selection as an intelligent power; in the same way as astronomers speak
of the attraction of gravity as ruling the movements of the planets, or
as agriculturists speak of man making domestic races by his power of
selection. In the one case, as in the other, selection does nothing
without variability, and this depends in some manner on the action of
the surrounding circumstances in the organism. I have, also, often
personified the word Nature; for I have found it difficult to avoid
this ambiguity; but I mean by nature only the aggregate action and
product of many natural laws, and by laws only the ascertained sequence
of events.
AN INVENTED HYPOTHESIS.
[Animals and
Plants, vol.
i, page 9.]
In scientific investigations it is permitted to invent any hypothesis,
and if it explains various large and independent classes of facts it
rises to the rank of a well-grounded theory. The undulations of the
ether and even its existence are hypothetical, yet every one now admits
the undulatory theory of light. The principle of natural selection
may be looked at as a mere hypothesis, but rendered in some degree
probable by what we positively know of the variability of organic
beings in a state of nature--by what we positively know of the struggle
for existence, and the consequent almost inevitable preservation of
favorable variations--and from the analogical formation of domestic
races. Now, this hypothesis may be tested--and this seems to me the
only fair and legitimate manner of considering the whole question--by
trying whether it explains several large and independent classes of
facts; such as the geological succession of organic beings, their
distribution in past and present times, and their mutual affinities
and homologies. If the principle of natural selection does explain
these and other large bodies of facts, it ought to be received. On the
ordinary view of each species having been independently created, we
gain no scientific explanation of any one of these facts. We can only
say that it has so pleased the Creator to command that the past and
present inhabitants of the world should appear in a certain order and
in certain areas; that he has impressed on them the most extraordinary
resemblances, and has classed them in groups subordinate to groups. But
by such statements we gain no new knowledge; we do not connect together
facts and laws; we explain nothing.
* * * * *
[Page 12.]
These facts have as yet received no explanation on the theory of
independent creation; they can not be grouped together under one point
of view, but each has to be considered as an ultimate fact. As the
first origin of life on this earth, as well as the continued life of
each individual, is at present quite beyond the scope of science, I
do not wish to lay much stress on the greater simplicity of the view
of a few forms or of only one form having been originally created,
instead of innumerable miraculous creations having been necessary at
innumerable periods; though this more simple view accords well with
Maupertuis’s philosophical axiom of “least action.”
HOW FAR THE THEORY MAY BE EXTENDED.
[Page 13.]
In considering how far the theory of natural selection may be
extended--that is, in determining from how many progenitors the
inhabitants of the world have descended--we may conclude that at
least all the members of the same class have descended from a single
ancestor. A number of organic beings are included in the same class,
because they present, independently of their habits of life, the same
fundamental type of structure, and because they graduate into each
other. Moreover, members of the same class can in most cases be shown
to be closely alike at an early embryonic age. These facts can be
explained on the belief of their descent from a common form; therefore
it may be safely admitted that all the members of the same class are
descended from one progenitor. But as the members of quite distinct
classes have something in common in structure and much in common in
constitution, analogy would lead us one step further, and to infer
as probable that all living creatures are descended from a single
prototype.
* * * * *
[Descent of
Man, part I.,
page 61.]
Thus a 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 perhaps 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;
but I am convinced, from the light gained during even the last few
years, that very many structures which now appear to us useless will
hereafter be proved to be useful, and will therefore come within the
range of natural selection. Nevertheless, I did not formerly consider
sufficiently the existence of structures, which, as far as we can at
present judge, are 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 show 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. I
was not, however, able to annul the influence of my former belief,
then almost universal, that each species had been purposely created;
and this led to my tacit assumption that every detail of structure,
excepting rudiments, was of some special, though unrecognized, service.
Any one with this assumption in his mind would naturally extend too far
the action of natural selection, either during past or present times.
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 very 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.
IS THERE ANY LIMIT TO WHAT SELECTION CAN EFFECT?
[Animals and
Plants, vol.
ii, page 228.]
The foregoing discussion naturally leads to the question, What is the
limit to the possible amount of variation in any part or quality, and,
consequently, is there any limit to what selection can effect? Will a
race-horse ever be reared fleeter than Eclipse? Can our prize cattle
and sheep be still further improved? Will a gooseberry ever weigh more
than that produced by “London” in 1852? Will the beet-root in France
yield a greater percentage of sugar? Will future varieties of wheat and
other grain produce heavier crops than our present varieties? These
questions can not be positively answered; but it is certain that we
ought to be cautious in answering them by a negative. In some lines of
variation the limit has probably been reached. Youatt believes that
the reduction of bone in some of our sheep has already been carried so
far that it entails great delicacy of constitution.
* * * * *
[Page 229.]
No doubt there is a limit beyond which the organization can not
be modified compatibly with health or life. The extreme degree of
fleetness, for instance, of which a terrestrial animal is capable, may
have been acquired by our present race-horses; but, as Mr. Wallace
has well remarked, the question that interests us “is not whether
indefinite and unlimited change in any or all directions is possible,
but whether such differences as do occur in nature could have been
produced by the accumulation of varieties by selection.” And in the
case of our domestic productions, there can be no doubt that many parts
of the organization, to which man has attended, have been thus modified
to a greater degree than the corresponding parts in the natural species
of the same genera or even families. We see this in the form and size
of our light and heavy dogs or horses, in the beak and many other
characters of our pigeons, in the size and quality of many fruits, in
comparison with the species belonging to the same natural groups.
HAS ORGANIZATION ADVANCED?
[Origin of
Species,
page 308.]
The problem whether organization on the whole has advanced is in
many ways excessively intricate. The geological record, at all times
imperfect, does not extend far enough back to show with unmistakable
clearness that within the known history of the world organization has
largely advanced. Even at the present day, looking to members of the
same class, naturalists are not unanimous which forms ought to be
ranked as highest: thus, some look at the selaceans or sharks, from
their approach in some important points of structure to reptiles, as
the highest fish; others look at the teleosteans as the highest. The
ganoids stand intermediate between the selaceans and teleosteans;
the latter at the present day are largely preponderant in number;
but formerly selaceans and ganoids alone existed; and in this case,
according to the standard of highness chosen, so will it be said
that fishes have advanced or retrograded in organization. To attempt
to compare members of distinct types in the scale of highness seems
hopeless; who will decide whether a cuttle-fish be higher than a
bee--that insect which the great Von Baer believed to be “in fact
more highly organized than a fish, although upon another type”? In
the complex struggle for life it is quite credible that crustaceans,
not very high in their own class, might beat cephalopods, the highest
mollusks; and such crustaceans, though not highly developed, would
stand very high in the scale of invertebrate animals, if judged by
the most decisive of all trials--the law of battle. Besides these
inherent difficulties in deciding which forms are the most advanced
in organization, we ought not solely to compare the highest members
of a class at any two periods--though undoubtedly this is one and
perhaps the most important element in striking a balance--but we ought
to compare all the members, high and low, at the two periods. At an
ancient epoch the highest and lowest molluscoidal animals, namely,
cephalopods and brachiopods, swarmed in numbers; at the present
time both groups are greatly reduced, while others, intermediate in
organization, have largely increased; consequently some naturalists
maintain that mollusks were formerly more highly developed than at
present; but a stronger case can be made out on the opposite side, by
considering the vast reduction of brachiopods, and the fact that our
existing cephalopods, though few in number, are more highly organized
than their ancient representatives. We ought also to compare the
relative proportional numbers at any two periods of the high and low
classes throughout the world; if, for instance, at the present day
fifty thousand kinds of vertebrate animals exist, and if we knew that
at some former period only ten thousand kinds existed, we ought to look
at this increase in number in the highest class, which implies a great
displacement of lower forms, as a decided advance in the organization
of the world. We thus see how hopelessly difficult it is to compare
with perfect fairness, under such extremely complex relations, the
standard of organization of the imperfectly-known faunas of successive
periods.
* * * * *
[Origin of
Species,
page 121.]
There may truly be said to be a constant struggle going on between, on
the one hand, the tendency to reversion to a less perfect state, as
well as an innate tendency to new variations, and, on the other hand,
the power of steady selection to keep the breed true. In the long run
selection gains the day, and we do not expect to fail so completely
as to breed bird as coarse as a common tumbler-pigeon from a good
short-faced strain. But, as long as selection is rapidly going on, much
variability in the parts undergoing modification may always be expected.
A HIGHER WORKMANSHIP THAN MAN’S.
[Origin of
Species,
page 65.]
As man can produce, and certainly has produced, a great result by his
methodical and unconscious means of selection, what may not natural
selection affect? Man can act only on external and visible characters:
Nature, if I may be allowed to personify the natural preservation or
survival of the fittest, cares nothing for appearances, except in so
far as they are useful to any being. She can act on every internal
organ, on every shade of constitutional difference, on the whole
machinery of life. Man selects only for his own good: Nature only for
that of the being which she tends. Every selected character is fully
exercised by her, as is implied by the fact of their selection. Man
keeps the natives of many climates in the same country; he seldom
exercises each selected character in some peculiar and fitting manner;
he feeds a long and a short beaked pigeon on the same food; he does
not exercise a long-backed or long-legged quadruped in any peculiar
manner; he exposes sheep with long and short wool to the same climate.
He does not allow the most vigorous males to struggle for the females.
He does not rigidly destroy all inferior animals, but protects during
each varying season, as far as lies in his power, all his productions.
He often begins his selection by some half-monstrous form; or at
least by some modification prominent enough to catch the eye or to
be plainly useful to him. Under nature, the slightest differences of
structure or constitution may well turn the nicely-balanced scale in
the struggle for life, and so be preserved. How fleeting are the wishes
and efforts of man! how short his time! and consequently how poor will
be his results, compared with those accumulated by Nature during whole
geological periods! Can we wonder, then, that Nature’s productions
should be far “truer” in character than man’s productions; that they
should be infinitely better adapted to the most complex conditions of
life, and should plainly bear the stamp of far higher workmanship?
It may metaphorically be said that natural selection is daily and
hourly scrutinizing, throughout the world, the slightest variations:
rejecting those that are bad, preserving and adding up all that
are good; silently and insensibly working, _whenever and wherever
opportunity offers_, at the improvement of each organic being in
relation to its organic and inorganic conditions of life. We see
nothing of these slow changes in progress, until the hand of Time
has marked the lapse of ages, and then so imperfect is our view into
long-past geological ages that we see only that the forms of life are
now different from what they formerly were.
* * * * *
[Page 66.]
Although natural selection can act only through and for the good
of each being, yet characters and structures, which we are apt to
consider as of very trifling importance, may thus be acted on. When
we see leaf-eating insects green and bark-feeders mottled-gray, the
Alpine ptarmigan white in winter, the red-grouse the color of heather,
we must believe that these tints are of service to these birds and
insects in preserving them from danger. Grouse, if not destroyed at
some period of their lives, would increase in countless numbers; they
are known to suffer largely from birds of prey; and hawks are guided
by eye-sight to their prey--so much so, that on parts of the Continent
persons are warned not to keep white pigeons, as being the most liable
to destruction. Hence natural selection might be effective in giving
the proper color to each kind of grouse, and in keeping that color,
when once acquired, true and constant. Nor ought we to think that the
occasional destruction of an animal of any particular color would
produce little effect: we should remember how essential it is in a
flock of white sheep to destroy a lamb with the faintest trace of black.
WHY HABITS AND STRUCTURE ARE NOT IN AGREEMENT.
[Origin of
Species,
page 142.]
He who believes that each being has been created as we now see it must
occasionally have felt surprise when he has met with an animal having
habits and structure not in agreement. What can be plainer than that
the webbed feet of ducks and geese are formed for swimming? Yet there
are upland geese with webbed feet which rarely go near the water; and
no one except Audubon has seen the frigate-bird, which has all its four
toes webbed, alight on the surface of the ocean. On the other hand,
grebes and coots are eminently aquatic, although their toes are only
bordered by membrane. What seems plainer than that the long toes, not
furnished with membrane, of the _Grallatores_, are formed for walking
over swamps and floating plants?--the water-hen and land-rail are
members of this order, yet the first is nearly as aquatic as the coot,
and the second nearly as terrestrial as the quail or partridge. In such
cases, and many others could be given, habits have changed without a
corresponding change of structure. The webbed feet of the upland goose
may be said to have become almost rudimentary in function, though not
in structure. In the frigate-bird, the deeply-scooped membrane between
the toes shows that structure has begun to change.
He who believes in separate and innumerable acts of creation may
say that in these cases it has pleased the Creator to cause a being
of one type to take the place of one belonging to another type; but
this seems to me only restating the fact in dignified language. He
who believes in the struggle for existence and in the principle
of natural selection, will acknowledge that every organic being is
constantly endeavoring to increase in numbers; and that if any one
being varies ever so little, either in habits or structure, and thus
gains an advantage over some other inhabitant of the same country, it
will seize on the place of that inhabitant, however different that may
be from its own place. Hence it will cause him no surprise that there
should be geese and frigate-birds with webbed feet, living on the dry
land and rarely alighting on the water; that there should be long-toed
corn-crakes, living in meadows instead of in swamps; that there should
be woodpeckers where hardly a tree grows; that there should be diving
thrushes and diving _Hymenoptera_, and petrels with the habits of auks.
NO MODIFICATION IN ONE SPECIES DESIGNED FOR THE GOOD OF ANOTHER.
[Origin of
Species,
page 162.]
Natural selection can not possibly produce any modification in a
species exclusively for the good of another species; though throughout
nature one species incessantly takes advantage of, and profits by, the
structures of others. But natural selection can and does often produce
structures for the direct injury of other animals, as we see in the
fang of the adder, and in the ovipositor of the ichneumon, by which its
eggs are deposited in the living bodies of other insects. If it could
be proved that any part of the structure of any one species had been
formed for the exclusive good of another species, it would annihilate
my theory, for such could not have been produced through natural
selection. Although many statements may be found in works on natural
history to this effect, I can not find even one which seems to me of
any weight. It is admitted that the rattlesnake has a poison-fang for
its own defense, and for the destruction of its prey; but some authors
suppose that at the same time it is furnished with a rattle for its
own injury, namely, to warn its prey. I would almost as soon believe
that the cat curls the end of its tail when preparing to spring, in
order to warn the doomed mouse. It is a much more probable view that
the rattlesnake uses its rattle, the cobra expands its frill, and the
puff-adder swells while hissing so loudly and harshly, in order to
alarm the many birds and beasts which are known to attack even the
most venomous species. Snakes act on the same principle which makes
the hen ruffle her feathers and expand her wings when a dog approaches
her chickens; but I have not space here to enlarge on the many ways by
which animals endeavor to frighten away their enemies.
Natural selection will never produce in a being any structure more
injurious than beneficial to that being, for natural selection acts
solely by and for the good of each. No organ will be formed, as Paley
has remarked, for the purpose of causing pain or for doing an injury to
its possessor. If a fair balance be struck between the good and evil
caused by each part, each will be found on the whole advantageous.
After the lapse of time, under changing conditions of life, if any part
comes to be injurious, it will be modified; or, if it be not so, the
being will become extinct as myriads have become extinct.
Natural selection tends only to make each organic being as perfect
as, or slightly more perfect than, the other inhabitants of the same
country with which it comes into competition. And we see that this
is the standard of perfection attained under nature. The endemic
productions of New Zealand, for instance, are perfect one compared
with another; but they are now rapidly yielding before the advancing
legions of plants and animals introduced from Europe. Natural selection
will not produce absolute perfection, nor do we always meet, as far as
we can judge, with this high standard under nature. The correction for
the aberration of light is said by Müller not to be perfect even in
that most perfect organ, the human eye.
* * * * *
[Page 67.]
Natural selection will modify the structure of the young in relation
to the parent, and of the parent in relation to the young. In social
animals it will adapt the structure of each individual for the benefit
of the whole community, if the community profits by the selected
change. What natural selection can not do is, to modify the structure
of one species, without giving it any advantage, for the good of
another species; and, though statements to this effect may be found
in works of natural history, I can not find one case which will bear
investigation. A structure used only once in an animal’s life, if of
high importance to it, might be modified to any extent by natural
selection; for instance, the great jaws possessed by certain insects,
used exclusively for opening the cocoon, or the hard tip to the beak of
unhatched birds, used for breaking the egg. It has been asserted that,
of the best short-beaked tumbler-pigeons, a greater number perish in
the egg than are able to get out of it, so that fanciers assist in the
act of hatching. Now, if Nature had to make the beak of a full-grown
pigeon very short for the bird’s own advantage, the process of
modification would be very slow, and there would be simultaneously the
most rigorous selection of all the young birds within the egg, which
had the most powerful and hardest beaks, for all with weak beaks would
inevitably perish; or, more delicate and more easily broken shells
might be selected, the thickness of the shell being known to vary like
every other structure.
ILLUSTRATIONS OF THE ACTION OF NATURAL SELECTION.
[Origin of
Species,
page 70.]
In order to make it clear how, as I believe, natural selection acts, I
must beg permission to give one or two imaginary illustrations. Let us
take the case of a wolf, which preys on various animals, securing some
by craft, some by strength, and some by fleetness; and let us suppose
that the fleetest prey, a deer for instance, had from any change in
the country increased in numbers, or that other prey had decreased
in numbers, during that season of the year when the wolf was hardest
pressed for food. Under such circumstances the swiftest and slimmest
wolves would have the best chance of surviving, and so be preserved or
selected--provided always that they retained strength to master their
prey at this or some other period of the year, when they were compelled
to prey on other animals. I can see no more reason to doubt that this
would be the result, than that man should be able to improve the
fleetness of his greyhounds by careful and methodical selection, or by
that kind of unconscious selection which follows from each man trying
to keep the best dogs without any thought of modifying the breed. I
may add that, according to Mr. Pierce, there are two varieties of the
wolf inhabiting the Catskill Mountains in the United States, one with
a light greyhound-like form, which pursues deer, and the other more
bulky, with shorter legs, which more frequently attacks the shepherd’s
flocks.
* * * * *
[Page 73.]
Certain plants excrete sweet juice, apparently for the sake of
eliminating something injurious from the sap: this is effected, for
instance, by glands at the base of the stipules in some _Leguminosæ_,
and at the backs of the leaves of the common laurel. This juice, though
small in quantity, is greedily sought by insects; but their visits do
not in any way benefit the plant. Now, let us suppose that the juice
or nectar was excreted from the inside of the flowers of a certain
number of plants of any species. Insects in seeking the nectar would
get dusted with pollen, and would often transport it from one flower to
another. The flowers of two distinct individuals of the same species
would thus get crossed; and the act of crossing, as can be fully
proved, gives rise to vigorous seedlings, which consequently would
have the best chance of flourishing and surviving. The plants which
produced flowers with the largest glands or nectaries, excreting most
nectar, would oftenest be visited by insects, and would oftenest be
crossed; and so in the long run would gain the upper hand and form a
local variety. The flowers, also, which had their stamens and pistils
placed, in relation to the size and habits of the particular insect
which visited them, so as to favor in any degree the transportal of
the pollen, would likewise be favored. We might have taken the case of
insects visiting flowers for the sake of collecting pollen instead of
nectar; and, as pollen is formed for the sole purpose of fertilization,
its destruction appears to be a simple loss to the plant; yet if a
little pollen were carried, at first occasionally and then habitually,
by the pollen-devouring insects from flower to flower, and a cross
thus effected, although nine tenths of the pollen were destroyed,
it might still be a great gain to the plant to be thus robbed; and
the individuals which produced more and more pollen, and had larger
anthers, would be selected.
When our plant, by the above process long continued, had been rendered
highly attractive to insects, they would, unintentionally on their
part, regularly carry pollen from flower to flower.
DIVERGENCE OF CHARACTER.
[Page 86.]
According to my view, varieties are species in the process of
formation, or are, as I have called them, incipient species. How, then,
does the lesser difference between varieties become augmented into the
greater difference between species? That this does habitually happen,
we must infer from most of the innumerable species throughout nature
presenting well-marked differences; whereas varieties, the supposed
prototypes and parents of future well-marked species, present slight
and ill-defined differences. Mere chance, as we may call it, might
cause one variety to differ in some character from its parents, and
the offspring of this variety again to differ from its parent in the
very same character and in a greater degree; but this alone would
never account for so habitual and large a degree of difference as that
between the species of the same genus.
As has always been my practice, I have sought light on this head from
our domestic productions. We shall here find something analogous.
It will be admitted that the production of races so different as
short-horn and Hereford cattle, race and cart horses, the several
breeds of pigeons, etc., could never have been effected by the mere
chance accumulation of similar variations during many successive
generations. In practice, a fancier is, for instance, struck by a
pigeon having a slightly shorter beak; another fancier is struck by a
pigeon having a rather longer beak; and, on the acknowledged principle
that “fanciers do not and will not admire a medium standard, but
like extremes,” they both go on (as has actually occurred with the
sub-breeds of the tumbler-pigeon) choosing and breeding from birds
with longer and longer beaks, or with shorter and shorter beaks.
Again, we may suppose that, at an early period of history, the men
of one nation or district required swifter horses, while those of
another required stronger and bulkier horses. The early differences
would be very slight; but, in the course of time, from the continued
selection of swifter horses in the one case, and of stronger ones in
the other, the differences would become greater, and would be noted
as forming two sub-breeds. Ultimately, after the lapse of centuries,
these sub-breeds would become converted into two well-established
and distinct breeds. As the differences became greater, the inferior
animals with intermediate characters, being neither very swift nor
very strong, would not have been used for breeding, and will thus have
tended to disappear. Here, then, we see in man’s productions the action
of what may be called the principle of divergence, causing differences,
at first barely appreciable, steadily to increase, and the breeds to
diverge in character, both from each other and from their common parent.
But how, it may be asked, can any analogous principle apply in nature?
I believe it can and does apply most efficiently (though it was a long
time before I saw how), from the simple circumstance that the more
diversified the descendants from any one species become in structure,
constitution, and habits, by so much will they be better enabled to
seize on many and widely diversified places in the polity of nature,
and so be enabled to increase in numbers.
* * * * *
[Page 89.]
The advantage of diversification of structure in the inhabitants of the
same region is, in fact, the same as that of the physiological division
of labor in the organs of the same individual body--a subject so well
elucidated by Milne-Edwards. No physiologist doubts that a stomach
adapted to digest vegetable matter alone, or flesh alone, draws most
nutriment from these substances. So in the general economy of any land,
the more widely and perfectly the animals and plants are diversified
for different habits of life, so will a greater number of individuals
be capable of there supporting themselves. A set of animals, with
their organization but little diversified, could hardly compete with
a set more perfectly diversified in structure. It may be doubted, for
instance, whether the Australian marsupials, which are divided into
groups differing but little from each other, and feebly representing,
as Mr. Waterhouse and others have remarked, our carnivorous,
ruminant, and rodent mammals, could successfully compete with these
well-developed orders. In the Australian mammals, we see the process of
diversification in an early and incomplete stage of development.
EVOLUTION OF THE HUMAN EYE.
[Origin of
Species,
page 143.]
To suppose that the eye with all its inimitable contrivances for
adjusting the focus to different distances, for admitting different
amounts of light, and for the correction of spherical and chromatic
aberration, could have been formed by natural selection, seems, I
freely confess, absurd in the highest degree. When it was first said
that the sun stood still and the world turned round, the common sense
of mankind declared the doctrine false; but the old saying of _Vox
populi vox Dei_, as every philosopher knows, can not be trusted in
science.
* * * * *
[Page 145.]
Within the highest division of the animal kingdom, namely, the
_Vertebrata_, we can start from an eye so simple that it consists, as
in the lancelet, of a little sac of transparent skin, furnished with
a nerve and lined with pigment, but destitute of any other apparatus.
In fishes and reptiles, as Owen has remarked, “the range of gradations
of dioptric structures is very great.” It is a significant fact that
even in man, according to the high authority of Virchow, the beautiful
crystalline lens is formed in the embryo by an accumulation of
epidermic cells, lying in a sac-like fold of the skin; and the vitreous
body is formed from embryonic subcutaneous tissue. To arrive, however,
at a just conclusion regarding the formation of the eye, with all its
marvelous yet not absolutely perfect characters, it is indispensable
that the reason should conquer the imagination; but I have felt the
difficulty far too keenly to be surprised at others hesitating to
extend the principle of natural selection to so startling a length.
It is scarcely possible to avoid comparing the eye with a telescope.
We know that this instrument has been perfected by the long-continued
efforts of the highest human intellects; and we naturally infer that
the eye has been formed by a somewhat analogous process. But may not
this inference be presumptuous? Have we any right to assume that the
Creator works by intellectual powers like those of man? If we must
compare the eye to an optical instrument, we ought in imagination to
take a thick layer of transparent tissue, with spaces filled with
fluid, and with a nerve sensitive to light beneath, and then suppose
every part of this layer to be continually changing slowly in density,
so as to separate into layers of different densities and thicknesses,
placed at different distances from each other, and with the surfaces
of each layer slowly changing in form. Further, we must suppose that
there is a power, represented by natural selection or the survival
of the fittest, always intently watching each slight alteration in
the transparent layers; and carefully preserving each which, under
varied circumstances, in any way or in any degree, tends to produce
a distincter image. We must suppose each new state of the instrument
to be multiplied by the million; each to be preserved until a better
one is produced, and then the old ones to be all destroyed. In living
bodies, variation will cause the slight alterations, generation will
multiply them almost infinitely, and natural selection will pick out
with unerring skill each improvement. Let this process go on for
millions of years; and during each year on millions of individuals of
many kinds; and may we not believe that a living optical instrument
might thus be formed as superior to one of glass as the works of the
Creator are to those of man?
VI.
GEOGRAPHICAL DISTRIBUTION OF ORGANIC BEINGS.
[Origin of
Species,
page 320.]
We are thus brought to the question which has been largely discussed
by naturalists, namely, whether species have been created at one or
more points of the earth’s surface. Undoubtedly there are many cases of
extreme difficulty in understanding how the same species could possibly
have migrated from some one point to the several distant and isolated
points where now found. Nevertheless the simplicity of the view that
each species was first produced within a single region captivates the
mind. He who rejects it rejects the _vera causa_ of ordinary generation
with subsequent migration, and calls in the agency of a miracle. It is
universally admitted that in most cases the area inhabited by a species
is continuous; and that, when a plant or animal inhabits two points so
distant from each other, or with an interval of such a nature, that the
space could not have been easily passed over by migration, the fact
is given as something remarkable and exceptional. The incapacity of
migrating across a wide sea is more clear in the case of terrestrial
mammals than perhaps with any other organic beings; and, accordingly,
we find no inexplicable instances of the same mammals inhabiting
distant points of the world. No geologist feels any difficulty in
Great Britain possessing the same quadrupeds with the rest of Europe,
for they were no doubt once united. But, if the same species can be
produced at two separate points, why do we not find a single mammal
common to Europe and Australia or South America? The conditions of
life are nearly the same, so that a multitude of European animals and
plants have become naturalized in America and Australia; and some of
the aboriginal plants are identically the same at these distant points
of the northern and southern hemispheres. The answer, as I believe,
is, that mammals have not been able to migrate, whereas some plants,
from their varied means of dispersal, have migrated across the wide
and broken interspaces. The great and striking influence of barriers
of all kinds is intelligible only on the view that the great majority
of species have been produced on one side, and have not been able to
migrate to the opposite side. Some few families, many sub-families,
very many genera, and a still greater number of sections of genera,
are confined to a single region: and it has been observed by several
naturalists that the most natural genera, or those genera in which the
species are most closely related to each other, are generally confined
to the same country, or, if they have a wide range, that their range is
continuous. What a strange anomaly it would be, if a directly opposite
rule were to prevail, when we go down one step lower in the series,
namely, to the individuals of the same species, and these had not been,
at least at first, confined to some one region!
Hence it seems to me, as it has to many other naturalists, that the
view of each species having been produced in one area alone, and
having subsequently migrated from that area as far as its powers of
migration and subsistence under past and present conditions permitted,
is the most probable. Undoubtedly many cases occur, in which we can
not explain how the same species could have passed from one point
to the other. But the geographical and climatal changes, which have
certainly occurred within recent geological times, must have rendered
discontinuous the formerly continuous range of many species. So that we
are reduced to consider whether the exceptions to continuity of range
are so numerous and of so grave a nature that we ought to give up the
belief, rendered probable by general considerations, that each species
has been produced within one area, and has migrated thence as far as it
could.
ISOLATED CONTINENTS NEVER WERE UNITED.
[Origin of
Species,
page 324.]
Whenever it is fully admitted, as it will some day be, that each
species has proceeded from a single birthplace, and when in the course
of time we know something definite about the means of distribution, we
shall be enabled to speculate with security on the former extension
of the land. But I do not believe that it will ever be proved that
within the recent period most of our continents which now stand quite
separate have been continuously, or almost continuously, united with
each other, and with the many existing oceanic islands. Several facts
in distribution, such as the great difference in the marine faunas on
the opposite sides of almost every continent, the close relation of the
tertiary inhabitants of several lands and even seas to their present
inhabitants, the degree of affinity between the mammals inhabiting
islands with those of the nearest continent, being in part determined
(as we shall hereafter see) by the depth of the intervening ocean,
these and other such facts are opposed to the admission of such
prodigious geographical revolutions within the recent period as are
necessary on the view advanced by Forbes and admitted by his followers.
The nature and relative proportions of the inhabitants of oceanic
islands are likewise opposed to the belief of their former continuity
with continents. Nor does the almost universally volcanic composition
of such islands favor the admission that they are the wrecks of
sunken continents; if they had originally existed as continental
mountain-ranges, some at least of the islands would have been formed,
like other mountain-summits, of granite, metamorphic schists, old
fossiliferous and other rocks, instead of consisting of mere piles of
volcanic matter.
MEANS OF DISPERSAL.
[Page 326.]
Living birds can hardly fail to be highly effective agents in the
transportation of seeds. I could give many facts showing how frequently
birds of many kinds are blown by gales to vast distances across the
ocean. We may safely assume that under such circumstances their rate
of flight would often be thirty-five miles an hour; and some authors
have given a far higher estimate. I have never seen an instance of
nutritious seeds passing through the intestines of a bird; but hard
seeds of fruit pass uninjured through even the digestive organs of a
turkey. In the course of two months I picked up in my garden twelve
kinds of seeds out of the excrement of small birds, and these seemed
perfect, and some of them, which were tried, germinated. But the
following fact is more important: the crops of birds do not secrete
gastric juice, and do not, as I know by trial, injure in the least the
germination of seeds; now, after a bird has found and devoured a large
supply of food, it is positively asserted that all the grains do not
pass into the gizzard for twelve or even eighteen hours. A bird in this
interval might easily be blown to the distance of five hundred miles,
and hawks are known to look out for tired birds, and the contents of
their torn crops might thus readily get scattered. Some hawks and owls
bolt their prey whole, and, after an interval of from twelve to twenty
hours, disgorge pellets, which, as I know from experiments made in the
Zoölogical Gardens, include seeds capable of germination. Some seeds
of the oat, wheat, millet, canary, hemp, clover, and beet germinated
after having been from twelve to twenty-one hours in the stomachs of
different birds of prey; and two seeds of beet grew after having been
thus retained for two days and fourteen hours. Fresh-water fish, I
find, eat seeds of many land and water plants: fish are frequently
devoured by birds, and thus the seeds might be transported from place
to place. I forced many kinds of seeds into the stomachs of dead fish,
and then gave their bodies to fishing-eagles, storks, and pelicans;
these birds, after an interval of many hours, either rejected the seeds
in pellets or passed them in their excrement; and several of these
seeds retained the power of germination. Certain seeds, however, were
always killed by this process.
Locusts are sometimes blown to great distances from the land; I myself
caught one three hundred and seventy miles from the coast of Africa,
and have heard of others caught at greater distances.
* * * * *
[Page 328.]
As icebergs are known to be sometimes loaded with earth and stones, and
have even carried brushwood, bones, and the nest of a land-bird, it can
hardly be doubted that they must occasionally, as suggested by Lyell,
have transported seeds from one part to another of the Arctic and
Antarctic regions, and during the Glacial period from one part of the
now temperate regions to another. In the Azores, from the large number
of plants common to Europe, in comparison with the species on the other
islands of the Atlantic, which stand nearer to the mainland, and (as
remarked by Mr. H. C. Watson) from their somewhat northern character in
comparison with the latitude, I suspected that these islands had been
partly stocked by ice-borne seeds during the Glacial epoch.
THESE MEANS OF TRANSPORT NOT ACCIDENTAL.
[Page 329.]
These means of transport are sometimes called accidental, but this is
not strictly correct; the currents of the sea are not accidental, nor
is the direction of prevalent gales of wind. It should be observed
that scarcely any means of transport would carry seeds for very great
distances: for seeds do not retain their vitality when exposed for
a great length of time to the action of sea-water; nor could they
be long carried in the crops or intestines of birds. These means,
however, would suffice for occasional transport across tracts of sea
some hundred miles in breadth, or from island to island, or from a
continent to a neighboring island, but not from one distant continent
to another. The floras of distant continents would not by such means
become mingled; but would remain as distinct as they now are. The
currents, from their course, would never bring seeds from North
America to Britain, though they might and do bring seeds from the West
Indies to our western shores, where, if not killed by their very long
immersion in salt-water, they could not endure our climate. Almost
every year, one or two land-birds are blown across the whole Atlantic
Ocean, from North America to the western shores of Ireland and England;
but seeds could be transported by these rare wanderers only by one
means, namely, by dirt adhering to their feet or beaks, which is in
itself a rare accident. Even in this case, how small would be the
chance of a seed falling on favorable soil and coming to maturity! But
it would be a great error to argue that, because a well-stocked island,
like Great Britain, has not, as far as is known (and it would be very
difficult to prove this), received within the last few centuries,
through occasional means of transport, immigrants from Europe or any
other continent, a poorly-stocked island, though standing more remote
from the mainland, would not receive colonists by similar means. Out of
a hundred kinds of seeds or animals transported to an island, even if
far less well-stocked than Britain, perhaps not more than one would be
so well fitted to its new home as to become naturalized. But this is
no valid argument against what would be effected by occasional means
of transport, during the long lapse of geological time, while the
island was being upheaved, and before it had become fully stocked with
inhabitants. On almost bare land, with few or no destructive insects
or birds living there, nearly every seed which chanced to arrive, if
fitted for the climate, would germinate and survive.
DISPERSAL DURING THE GLACIAL PERIOD.
[Page 434.]
The Glacial period is defined “as a period of great cold and of
enormous extension of ice upon the surface of the earth. It is believed
that glacial periods have occurred repeatedly during the geological
history of the earth, but the term is generally applied to the close of
the Tertiary epoch, when nearly the whole of Europe was subjected to an
Arctic climate.”
* * * * *
[Origin of
Species,
page 330.]
The identity of many plants and animals, on mountain-summits, separated
from each other by hundreds of miles of lowlands, where Alpine species
could not possibly exist, is one of the most striking cases known
of the same species living at distant points, without the apparent
possibility of their having migrated from one point to the other. It
is indeed a remarkable fact to see so many plants of the same species
living on the snowy regions of the Alps or Pyrenees, and in the extreme
northern parts of Europe; but it is far more remarkable that the plants
on the White Mountains, in the United States of America, are all the
same with those of Labrador, and nearly all the same, as we hear from
Asa Gray, with those on the loftiest mountains of Europe. Even as long
ago as 1747 such facts led Gmelin to conclude that the same species
must have been independently created at many distinct points; and we
might have remained in this same belief, had not Agassiz and others
called vivid attention to the Glacial period, which, as we shall
immediately see, affords a simple explanation of these facts. We have
evidence of almost every conceivable kind, organic and inorganic,
that, within a very recent geological period, Central Europe and North
America suffered under an Arctic climate. The ruins of a house burned
by fire do not tell their tale more plainly than do the mountains of
Scotland and Wales, with their scored flanks, polished surfaces, and
perched bowlders, of the icy streams with which their valleys were
lately filled. So greatly has the climate of Europe changed, that in
Northern Italy gigantic moraines, left by old glaciers, are now clothed
by the vine and maize. Throughout a large part of the United States
erratic bowlders and scored rocks plainly reveal a former cold period.
The former influence of the glacial climate on the distribution of the
inhabitants of Europe, as explained by Edward Forbes, is substantially
as follows. But we shall follow the changes more readily by supposing a
new glacial period slowly to come on, and then pass away, as formerly
occurred. As the cold came on, and as each more southern zone became
fitted for the inhabitants of the north, these would take the places
of the former inhabitants of the temperate regions. The latter, at the
same time, would travel farther and farther southward, unless they were
stopped by barriers, in which case they would perish. The mountains
would become covered with snow and ice, and their former Alpine
inhabitants would descend to the plains. By the time that the cold had
reached its maximum, we should have an Arctic fauna and flora, covering
the central parts of Europe, as far south as the Alps and Pyrenees, and
even stretching into Spain. The now temperate regions of the United
States would likewise be covered by Arctic plants and animals, and
these would be nearly the same with those of Europe; for the present
circumpolar inhabitants, which we suppose to have everywhere traveled
southward, are remarkably uniform round the world.
As the warmth returned, the Arctic forms would retreat northward,
closely followed up in their retreat by the productions of the more
temperate regions. And, as the snow melted from the bases of the
mountains, the Arctic forms would seize on the cleared and thawed
ground, always ascending, as the warmth increased and the snow still
further disappeared, higher and higher, while their brethren were
pursuing their northern journey. Hence, when the warmth had fully
returned, the same species, which had lately lived together on the
European and North American lowlands, would again be found in the
Arctic regions of the Old and New Worlds, and on many isolated
mountain-summits far distant from each other.
Thus we can understand the identity of many plants at points so
immensely remote as the mountains of the United States and those of
Europe.
THE THEORY OF CREATION INADEQUATE.
[Page 334.]
As on the land, so in the waters of the sea, a slow southern migration
of a marine fauna, which, during the Pliocene or even a somewhat
earlier period, was nearly uniform along the continuous shores of the
Polar Circle, will account, on the theory of modification, for many
closely allied forms now living in marine areas completely sundered.
Thus, I think, we can understand the presence of some closely allied,
still existing and extinct tertiary forms on the eastern and western
shores of temperate North America; and the still more striking fact
of many closely allied crustaceans (as described in Dana’s admirable
work), some fish and other marine animals, inhabiting the Mediterranean
and the seas of Japan--these two areas being now completely separated
by the breadth of a whole continent and by wide spaces of ocean.
These cases of close relationship in species either now or formerly
inhabiting the seas on the eastern and western shores of North America,
the Mediterranean and Japan, and the temperate lands of North America
and Europe, are inexplicable on the theory of creation. We can not
maintain that such species have been created alike, in correspondence
with the nearly similar physical conditions of the areas; for, if we
compare, for instance, certain parts of South America with parts of
South Africa or Australia, we see countries closely similar in all
their physical conditions, with their inhabitants utterly dissimilar.
CAUSES OF A GLACIAL CLIMATE.
[Page 336.]
Mr. Croll, in a series of admirable memoirs, has attempted to show
that a glacial condition of climate is the result of various physical
causes, brought into operation by an increase in the eccentricity of
the earth’s orbit. All these causes tend toward the same end; but the
most powerful appears to be the indirect influence of the eccentricity
of the orbit upon oceanic currents. According to Mr. Croll, cold
periods regularly recur every ten to fifteen thousand years; and these
at long intervals are extremely severe, owing to certain contingencies,
of which the most important, as Sir C. Lyell has shown, is the relative
position of the land and water. Mr. Croll believes that the last great
Glacial period occurred about two hundred and forty thousand years ago,
and endured with slight alterations of climate for about one hundred
and sixty thousand years. With respect to more ancient Glacial periods,
several geologists are convinced from direct evidence that such
occurred during the Miocene and Eocene formations, not to mention still
more ancient formations. But the most important result for us, arrived
at by Mr. Croll, is that, whenever the northern hemisphere passes
through a cold period, the temperature of the southern hemisphere is
actually raised, with the winters rendered much milder, chiefly through
changes in the direction of the ocean-currents. So conversely it will
be with the northern hemisphere, while the southern passes through a
glacial period. This conclusion throws so much light on geographical
distribution that I am strongly inclined to trust in it.
DIFFICULTIES NOT YET REMOVED.
[Page 341.]
I am far from supposing that all the difficulties in regard to the
distribution and affinities of the identical and allied species, which
now live so widely separated in the north and south, and sometimes on
the intermediate mountain-ranges, are removed on the views above given.
The exact lines of migration can not be indicated. We can not say why
certain species and not others have migrated; why certain species have
been modified and have given rise to new forms, while others have
remained unaltered. We can not hope to explain such facts, until we can
say why one species and not another becomes naturalized by man’s agency
in a foreign land; why one species ranges twice or thrice as far, and
is twice or thrice as common, as another species within their own homes.
Various special difficulties also remain to be solved; for instance,
the occurrence, as shown by Dr. Hooker, of the same plants at points
so enormously remote as Kerguelen Land, New Zealand, and Fuegia; but
icebergs, as suggested by Lyell, may have been concerned in their
dispersal. The existence at these and other distant points of the
southern hemisphere of species which, though distinct, belong to genera
exclusively confined to the south, is a more remarkable case. Some of
these species are so distinct that we can not suppose that there has
been time since the commencement of the last Glacial period for their
migration and subsequent modification to the necessary degree. The
facts seem to indicate that distinct species belonging to the same
genera have migrated in radiating lines from a common center; and I am
inclined to look in the southern, as in the northern hemisphere, to a
former and warmer period, before the commencement of the last Glacial
period, when the Antarctic lands, now covered with ice, supported a
highly peculiar and isolated flora. It may be suspected that, before
this flora was exterminated during the last Glacial epoch, a few forms
had been already widely dispersed to various points of the southern
hemisphere by occasional means of transport, and by the aid, as
halting-places, of now sunken islands. Thus the southern shores of
America, Australia, and New Zealand, may have become slightly tinted by
the same peculiar forms of life.
IDENTITY OF THE SPECIES OF ISLANDS WITH THOSE OF THE MAINLAND EXPLAINED
ONLY BY THIS THEORY.
[Origin of
Species,
page 353.]
The most striking and important fact for us is the affinity of the
species which inhabit islands to those of the nearest mainland,
without being actually the same. Numerous instances could be given.
The Galapagos Archipelago, situated under the equator, lies at the
distance of between five hundred and six hundred miles from the shores
of South America. Here almost every product of the land and of the
water bears the unmistakable stamp of the American Continent. There are
twenty-six land-birds; of these, twenty-one or perhaps twenty-three
are ranked as distinct species, and would commonly be assumed to have
been here created; yet the close affinity of most of these birds to
American species is manifest in every character, in their habits,
gestures, and tones of voice. So it is with the other animals, and
with a large proportion of the plants, as shown by Dr. Hooker in
his admirable Flora of this archipelago. The naturalist, looking at
the inhabitants of these volcanic islands in the Pacific, distant
several hundred miles from the continent, feels that he is standing
on American land. Why should this be so? why should the species
which are supposed to have been created in the Galapagos Archipelago,
and nowhere else, bear so plainly the stamp of affinity to those
created in America? There is nothing in the conditions of life, in the
geological nature of the islands, in their height or climate, or in
the proportions in which the several classes are associated together,
which closely resembles the conditions of the South American coast;
in fact, there is a considerable dissimilarity in all these respects.
On the other hand, there is a considerable degree of resemblance in
the volcanic nature of the soil, in the climate, height, and size of
the islands, between the Galapagos and Cape de Verd Archipelagos;
but what an entire and absolute difference in their inhabitants! The
inhabitants of the Cape de Verd Islands are related to those of Africa,
like those of the Galapagos to America. Facts such as these admit of
no sort of explanation on the ordinary view of independent creation;
whereas, on the view here maintained, it is obvious that the Galapagos
Islands would be likely to receive colonists from America, whether
by occasional means of transport or (though I do not believe in this
doctrine) by formerly continuous land, and the Cape de Verd Islands
from Africa; such colonists would be liable to modification, the
principle of inheritance still betraying their original birthplace.
Many analogous facts could be given: indeed, it is an almost universal
rule that the endemic productions of islands are related to those of
the nearest continent, or of the nearest large island. The exceptions
are few, and most of them can be explained. Thus, although Kerguelen
Land stands nearer to Africa than to America, the plants are related,
and that very closely, as we know from Dr. Hooker’s account, to those
of America: but, on the view that this island has been mainly stocked
by seeds brought with earth and stones on icebergs, drifted by the
prevailing currents, this anomaly disappears. New Zealand in its
endemic plants is much more closely related to Australia, the nearest
mainland, than to any other region: and this is what might have been
expected; but it is also plainly related to South America, which,
although the next nearest continent, is so enormously remote that the
fact becomes an anomaly. But this difficulty partially disappears on
the view that New Zealand, South America, and the other southern lands
have been stocked in part from a nearly intermediate though distant
point, namely, from the Antarctic islands, when they were clothed with
vegetation, during a warmer tertiary period, before the commencement
of the last Glacial period. The affinity, which, though feeble, I am
assured by Dr. Hooker is real, between the flora of the southwestern
corner of Australia and of the Cape of Good Hope, is a far more
remarkable case; but this affinity is confined to the plants, and will,
no doubt, some day be explained.
VII.
EVIDENCE OF THE DESCENT OF MAN FROM SOME LOWER FORM.
[The Descent
of Man,
page 5.]
He who wishes to decide whether man is the modified descendant of some
pre-existing form would probably first inquire 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. 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, etc.? Is
man subject to similar malconformations, the result of arrested
development, of reduplication of parts, etc., and does he display
in any of his anomalies reversion to some former and ancient type
of structure? It might also naturally be inquired 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 in the first and succeeding generations? And so with many
other points.
The inquirer 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 one another, 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.
POINTS OF CORRESPONDENCE BETWEEN MAN AND THE OTHER ANIMALS.
[The Descent
of Man,
page 6.]
It is notorious that man is constructed on the same general type or
model as 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 shown by
Huxley and other anatomists. Bischoff, 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 perfect agreement be expected,
for otherwise their mental powers would have been the same.
* * * * *
Man is liable to receive from the lower animals, and to communicate
to them, certain diseases, as hydrophobia, variola, the glanders,
syphilis, cholera, herpes, etc.; 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, 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 Northeastern 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
behavior 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. 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 as those infesting other mammals, and in
the case of scabies to the same species. 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. His wounds
are repaired by the same process of healing; and the stumps left after
the amputation of his limbs, especially during an early embryonic
period, occasionally possess some power of regeneration, as in the
lowest animals.
* * * * *
[Page 9.]
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 side of the neck still remain, 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 Professor Huxley, “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.”
THE FACTS OF EMBRYOLOGY AND THE THEORY OF DEVELOPMENT.
[Origin of
Species,
page 386.]
This is one of the most important subjects (embryology) in the whole
round of natural history. The metamorphoses of insects, with which
every one is familiar, are generally effected abruptly by a few
stages; but the transformations are in reality numerous and gradual,
though concealed. A certain ephemerous insect (_Chlöeon_), during its
development, molts, as shown by Sir J. Lubbock, above twenty times,
and each time undergoes a certain amount of change; and in this case
we see the act of metamorphosis performed in a primary and gradual
manner. Many insects, and especially certain crustaceans, show us what
wonderful changes of structure can be effected during development.
Such changes, however, reach their climax in the so-called alternate
generations of some of the lower animals. It is, for instance, an
astonishing fact that a delicate branching coralline, studded with
polypi and attached to a submarine rock, should produce, first by
budding and then by transverse division, a host of huge floating
jelly-fishes; and that these should produce eggs, from which are
hatched swimming animalcules, which attach themselves to rocks, and
become developed into branching corallines; and so on in an endless
cycle. The belief in the essential identity of the process of alternate
generation and of ordinary metamorphosis has been greatly strengthened
by Wagner’s discovery of the larva or maggot of a fly, namely, the
_Cecidomyia_, producing asexually other larvæ, and these others, which
finally are developed into mature males and females, propagating their
kind in the ordinary manner by eggs.
* * * * *
[Page 387.]
It has been already stated that various parts in the same individual,
which are exactly alike during an early embryonic period, become widely
different and serve for widely different purposes in the adult state.
So, again, it has been shown that generally the embryos of the most
distinct species belonging to the same class are closely similar, but
become, when fully developed, widely dissimilar. A better proof of
this latter fact can not be given than the statement by Von Baer that
“the embryos of mammalia, of birds, lizards, and snakes, probably also
of chelonia, are in their earliest states exceedingly like one another,
both as a whole and in the mode of development of their parts; so much
so, in fact, that we can often distinguish the embryos only by their
size. In my possession are two little embryos in spirit, whose names
I have omitted to attach, and at present I am quite unable to say to
what class they belong. They may be lizards or small birds, or very
young mammalia, so complete is the similarity in the mode of formation
of the head and trunk in these animals. The extremities, however, are
still absent in these embryos. But, even if they had existed in the
earliest stage of their development, we should learn nothing, for the
feet of lizards and mammals, the wings and feet of birds, no less than
the hands and feet of man, all arise from the same fundamental form.”
The larvæ of most crustaceans, at corresponding stages of development,
closely resemble each other, however different the adults may become;
and so it is with very many other animals. A trace of the law of
embryonic resemblance occasionally lasts till a rather late age: thus
birds of the same genus, and of allied genera, often resemble each
other in their immature plumage; as we see in the spotted feathers in
the young of the thrush group. In the cat tribe, most of the species
when adult are striped or spotted in lines; and stripes or spots can
be plainly distinguished in the whelp of the lion and the puma. We
occasionally though rarely see something of the same kind in plants;
thus the first leaves of the ulex or furze, and the first leaves of the
phyllodineous acacias, are pinnate or divided like the ordinary leaves
of the _Leguminosæ_.
TWO PRINCIPLES THAT EXPLAIN THE FACTS.
[Page 390.]
How, then, can we explain these several facts in embryology--namely,
the very general, though not universal, difference in structure between
the embryo and the adult; the various parts in the same individual
embryo, which ultimately become very unlike and serve for diverse
purposes, being at an early period of growth alike; the common, but
not invariable, resemblance between the embryos or larvæ of the most
distinct species in the same class; the embryo often retaining, while
within the egg or womb, structures which are of no service to it,
either at that or at a later period of life; on the other hand, larvæ,
which have to provide for their own wants, being perfectly adapted to
the surrounding conditions; and, lastly, the fact of certain larvæ
standing higher in the scale of organization than the mature animal
into which they are developed? I believe that all these facts can be
explained as follows:
It is commonly assumed, perhaps from monstrosities affecting the
embryo at a very early period, that slight variations or individual
differences necessarily appear at an equally early period. We have
little evidence on this head, but what we have certainly points the
other way; for it is notorious that breeders of cattle, horses, and
various fancy animals, can not positively tell, until some time after
birth, what will be the merits or demerits of their young animals.
We see this plainly in our own children; we can not tell whether
a child will be tall or short, or what its precise features will
be. The question is not, at what period of life each variation may
have been caused, but at what period the effects are displayed. The
cause may have acted, and I believe often has acted, on one or both
parents before the act of generation. It deserves notice that it is
of no importance to a very young animal, as long as it remains in
its mother’s womb or in the egg, or as long as it is nourished and
protected by its parent, whether most of its characters are acquired a
little earlier or later in life. It would not signify, for instance, to
a bird which obtained its food by having a much-curved beak whether or
not while young it possessed a beak of this shape, as long as it was
fed by its parents.
I have stated in the first chapter that at whatever age a variation
first appears in the parent, it tends to reappear at a corresponding
age in the offspring. Certain variations can only appear at
corresponding ages; for instance, peculiarities in the caterpillar,
cocoon, or imago states of the silk-moth; or, again, in the full-grown
horns of cattle. But variations, which, for all that we can see, might
have first appeared either earlier or later in life, likewise tend to
reappear at a corresponding age in the offspring and parent. I am far
from meaning that this is invariably the case, and I could give several
exceptional cases of variations (taking the word in the largest sense)
which have supervened at an earlier age in the child than in the parent.
These two principles, namely, that slight variations generally
appear at a not very early period of life, and are inherited at a
corresponding not early period, explain, as I believe, all the above
specified leading facts in embryology.
EMBRYOLOGY AGAINST ABRUPT CHANGES.
[Origin of
Species,
page 203.]
Unless we admit transformations as prodigious as those advocated by
Mr. Mivart, such as the sudden development of the wings of birds or
bats, or the sudden conversion of a Hipparion into a horse, hardly any
light is thrown by the belief in abrupt modifications on the deficiency
of connecting links in our geological formations. But against the
belief in such abrupt changes embryology enters a strong protest. It
is notorious that the wings of birds and bats, and the legs of horses
or other quadrupeds, are undistinguishable at an early embryonic
period, and that they become differentiated by insensibly fine steps.
Embryological resemblances of all kinds can be accounted for, as we
shall hereafter see, by the progenitors of our existing species having
varied after early youth, and having transmitted their newly acquired
characters to their offspring at a corresponding age. The embryo
is thus left almost unaffected, and serves as a record of the past
condition of the species. Hence it is that existing species during
the early stages of their development so often resemble ancient and
extinct forms belonging to the same class. On this view of the meaning
of embryological resemblances, and indeed on any view, it is incredible
that an animal should have undergone such momentous and abrupt
transformations as those above indicated, and yet should not bear even
a trace in its embryonic condition of any sudden modification, every
detail in its structure being developed by insensibly fine steps.
He who believes that some ancient form was transformed suddenly through
an internal force or tendency into, for instance, one furnished with
wings, will be almost compelled to assume, in opposition to all
analogy, that many individuals varied simultaneously. It can not be
denied that such abrupt and great changes of structure are widely
different from those which most species apparently have undergone. He
will further be compelled to believe that many structures beautifully
adapted to all the other parts of the same creature and to the
surrounding conditions, have been suddenly produced; and of such
complex and wonderful coadaptations he will not be able to assign a
shadow of an explanation. He will be forced to admit that these great
and sudden transformations have left no trace of their action on the
embryo. To admit all this is, as it seems to me, to enter into the
realms of miracle, and to leave those of science.
RUDIMENTARY ORGANS ONLY TO BE EXPLAINED ON THE THEORY OF DEVELOPMENT.
[Descent of
Man, page 11.]
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
can hardly 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--a circumstance well worthy of attention.
* * * * *
[Page 12.]
Rudiments of various muscles have been observed in many parts of the
human body; 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, the muscle on the forehead, by which the eyebrows are
raised.
* * * * *
[Page 13.]
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 the 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 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 persistent may be the transmission
of an absolutely useless faculty, probably derived from our remote
semi-human progenitors, since many monkeys have, and frequently use,
the power of largely moving their scalps up and down.
* * * * *
[Page 23.]
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 shown by their occasional
sympathetic enlargement in both during an attack of the measles.
“NO OTHER EXPLANATION HAS EVER BEEN GIVEN.”
[Page 24.]
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, etc., 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 marvelous fact that the
embryos of a man, dog, seal, bat, reptile, etc., 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.
UNITY OF TYPE EXPLAINED BY RELATIONSHIP.
[Origin of
Species,
page 382.]
We have seen that the members of the same class, independently of
their habits of life, resemble each other in the general plan of their
organization. This resemblance is often expressed by the term “unity
of type”; or by saying that the several parts and organs in the
different species of the class are homologous. The whole subject is
included under the general term of Morphology. This is one of the most
interesting departments of natural history, and may almost be said to
be its very soul. What can be more curious than that the hand of a man,
formed for grasping, that of a mole for digging, the leg of the horse,
the paddle of the porpoise, and the wing of the bat, should all be
constructed on the same pattern, and should include similar bones, in
the same relative positions? How curious it is, to give a subordinate
though striking instance, that the hind-feet of the kangaroo, which
are so well fitted for bounding over the open plains, those of the
climbing, leaf-eating koala, equally well fitted for grasping the
branches of trees, those of the ground-dwelling, insect or root eating,
bandicoots, and those of some other Australian marsupials, should all
be constructed on the same extraordinary type, namely, with the bones
of the second and third digits extremely slender and enveloped within
the same skin, so that they appear like a single toe furnished with
two claws! Notwithstanding this similarity of pattern, it is obvious
that the hind-feet of these several animals are used for as widely
different purposes as it is possible to conceive. The case is rendered
all the more striking by the American opossums, which follow nearly
the same habits of life as some of their Australian relatives, having
feet constructed on the ordinary plan. Professor Flower, from whom
these statements are taken, remarks in conclusion, “We may call this
conformity to type, without getting much nearer to an explanation of
the phenomenon”; and he then adds, “but is it not powerfully suggestive
of true relationship, of inheritance from a common ancestor?”
INEXPLICABLE ON THE ORDINARY VIEW OF CREATION.
[Page 384.]
How inexplicable are the cases of serial homologies on the ordinary
view of creation! Why should the brain be inclosed in a box composed
of such numerous and such extraordinarily shaped pieces of bone,
apparently representing vertebræ? As Owen has remarked, the benefit
derived from the yielding of the separate pieces in the act of
parturition by mammals will by no means explain the same construction
in the skulls of birds and reptiles. Why should similar bones have been
created to form the wing and the leg of a bat, used as they are for
such totally different purposes, namely, flying and walking? Why should
one crustacean, which has an extremely complex mouth formed of many
parts, consequently always have fewer legs; or conversely, those with
many legs have simpler mouths? Why should the sepals, petals, stamens,
and pistils, in each flower, though fitted for such distinct purposes,
be all constructed on the same pattern?
On the theory of natural selection, we can, to a certain extent,
answer these questions. We need not here consider how the bodies of
some animals first became divided into a series of segments, or how
they became divided into right and left sides, with corresponding
organs, for such questions are almost beyond investigation. It is,
however, probable that some serial structures are the result of cells
multiplying by division, entailing the multiplication of the parts
developed from such cells. It must suffice for our purpose to bear
in mind that an indefinite repetition of the same part or organ is
the common characteristic, as Owen has remarked, of all low or little
specialized forms; therefore the unknown progenitor of the Vertebrata
probably possessed many vertebræ; the unknown progenitor of the
Articulata, many segments; and the unknown progenitor of flowering
plants, many leaves arranged in one or more spires. We have also
formerly seen that parts many times repeated are eminently liable to
vary, not only in number, but in form. Consequently such parts being
already present in considerable numbers, and being highly variable,
would naturally afford the materials for adaptation to the most
different purposes; yet they would generally retain, through the
force of inheritance, plain traces of their original or fundamental
resemblance. They would retain this resemblance all the more, as the
variations, which afforded the basis for their subsequent modification
through natural selection, would tend from the first to be similar, the
parts being at an early stage of growth alike, and being subjected to
nearly the same conditions. Such parts, whether more or less modified,
unless their common origin became wholly obscured, would be serially
homologous.
DESCENT WITH MODIFICATION THE ONLY EXPLANATION.
[Origin of
Species,
page 400.]
In works on natural history, rudimentary organs are generally said
to have been created “for the sake of symmetry,” or in order “to
complete the scheme of Nature.” But this is not an explanation, merely
a restatement of the fact. Nor is it consistent with itself: thus the
boa-constrictor has rudiments of hind-limbs and of a pelvis, and if it
be said that these bones have been retained “to complete the scheme of
Nature,” why, as Professor Weismann asks, have they not been retained
by other snakes, which do not possess even a vestige of these same
bones? What would be thought of an astronomer who maintained that the
satellites revolve in elliptic courses round their planets “for the
sake of symmetry,” because the planets thus revolve round the sun? An
eminent physiologist accounts for the presence of rudimentary organs,
by supposing that they serve to excrete matter in excess, or matter
injurious to the system; but can we suppose that the minute papilla,
which often represents the pistil in male flowers, and which is formed
of mere cellular tissue, can thus act? Can we suppose that rudimentary
teeth, which are subsequently absorbed, are beneficial to the rapidly
growing embryonic calf by removing matter so precious as phosphate of
lime? When a man’s fingers have been amputated, imperfect nails have
been known to appear on the stumps, and I could as soon believe that
these vestiges of nails are developed in order to excrete horny matter,
as that the rudimentary nails on the fin of the manatee have been
developed for this same purpose.
On the view of descent with modification, the origin of rudimentary
organs is comparatively simple; and we can understand to a large extent
the laws governing their imperfect development.
THE HISTORY OF LIFE ON THE THEORY OF DESCENT WITH MODIFICATION.
[Origin of
Species,
page 424.]
Organs in a rudimentary condition plainly show that an early progenitor
had the organ in a fully-developed condition; and this in some cases
implies an enormous amount of modification in the descendants.
Throughout whole classes various structures are formed on the same
pattern, and at a very early age the embryos closely resemble each
other. Therefore I can not doubt that the theory of descent with
modification embraces all the members of the same great class or
kingdom. I believe that animals are descended from at most only four
or five progenitors, and plants from an equal or lesser number.
Analogy would lead me one step further, namely, to the belief that all
animals and plants are descended from some one prototype. But analogy
may be a deceitful guide. Nevertheless, all living things have much
in common, in their chemical composition, their cellular structure,
their laws of growth, and their liability to injurious influences.
We see this even in so trifling a fact as that the same poison often
similarly affects plants and animals; or that the poison secreted by
the gall-fly produces monstrous growths on the wild-rose or oak-tree.
With all organic beings, excepting, perhaps, some of the very lowest,
sexual reproduction seems to be essentially similar. With all, as far
as is at present known, the germinal vesicle is the same; so that
all organisms start from a common origin. If we look even to the two
main divisions--namely, to the animal and vegetable kingdoms--certain
low forms are so far intermediate in character that naturalists have
disputed to which kingdom they should be referred. As Professor Asa
Gray has remarked, “the spores and other reproductive bodies of many of
the lower algæ may claim to have first a characteristically animal, and
then an unequivocally vegetable existence.” Therefore, on the principle
of natural selection with divergence of character, it does not seem
incredible that, from some such low and intermediate form, both animals
and plants may have been developed; and, if we admit this, we must
likewise admit that all the organic beings which have ever lived on
this earth may be descended from some one primordial form. But this
inference is chiefly grounded on analogy, and it is immaterial whether
or not it be accepted.
* * * * *
[Page 420.]
On the view of each organism with all its separate parts having been
specially created, how utterly inexplicable is it that organs bearing
the plain stamp of inutility, such as the teeth in the embryonic calf,
or the shriveled wings under the soldered wing-covers of many beetles,
should so frequently occur! Nature may be said to have taken pains to
reveal her scheme of modification, by means of rudimentary organs,
of embryological and homologous structures, but we are too blind to
understand her meaning.
LETTERS RETAINED IN THE SPELLING BUT USELESS IN PRONUNCIATION.
[Origin of
Species,
page 401.]
There remains, however, this difficulty. After an organ has ceased
being used, and has become in consequence much reduced, how can it be
still further reduced in size until the merest vestige is left; and
how can it be finally quite obliterated? It is scarcely possible that
disuse can go on producing any further effect after the organ has
once been rendered functionless. Some additional explanation is here
requisite which I can not give. If, for instance, it could be proved
that every part of the organization tends to vary in a greater degree
toward diminution than toward augmentation of size, then we should
be able to understand how an organ which has become useless would
be rendered, independently of the effects of disuse, rudimentary,
and would at last be wholly suppressed; for the variations toward
diminished size would no longer be checked by natural selection. The
principle of the economy of growth, explained in a former chapter, by
which the materials forming any part, if not useful to the possessor,
are saved as far as is possible, will perhaps come into play in
rendering a useless part rudimentary. But this principle will almost
necessarily be confined to the earlier stages of the process of
reduction; for we can not suppose that a minute papilla, for instance,
representing in a male flower the pistil of the female flower, and
formed merely of cellular tissue, could be further reduced or absorbed
for the sake of economizing nutriment.
Finally, as rudimentary organs, by whatever steps they may have been
degraded into their present useless condition, are the record of a
former state of things, and have been retained solely through the
power of inheritance, we can understand, on the genealogical view of
classification, how it is that systematists, in placing organisms in
their proper places in the natural system, have often found rudimentary
parts as useful as, or even sometimes more useful than, parts of high
physiological importance. Rudimentary organs may be compared with the
letters in a word, still retained in the spelling, but become useless
in the pronunciation, but which serve as a clew for its derivation.
On the view of descent with modification, we may conclude that the
existence of organs in a rudimentary, imperfect, and useless condition,
or quite aborted, far from presenting a strange difficulty, as they
assuredly do on the old doctrine of creation, might even have been
anticipated in accordance with the views here explained.
MAN’S DEFICIENCY IN TAIL.
[Descent of
Man, page 58.]
According to a popular impression, the absence of a tail is eminently
distinctive of man; but, as those apes which come nearest to him are
destitute of this organ, its disappearance does not relate exclusively
to man. The tail often differs remarkably in length within the same
genus: thus in some species of _Macacus_ it is longer than the whole
body, and is formed 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, while in the mandrill
there are ten very small stunted caudal vertebræ, or, according to
Cuvier, sometimes only five. The tail, whether it be long or short,
almost always tapers toward the end; and this, I presume, results from
the atrophy of the terminal muscles, together with their arteries
and nerves, through disuse, leading to the atrophy of the terminal
bones. But no explanation can at present be given of the great
diversity which often occurs in its length. Here, however, we are
more specially concerned with the complete external disappearance of
the tail. Professor Broca has recently shown that the tail in all
quadrupeds consists of two portions, generally separated abruptly
from each other; the basal portion consists of vertebræ, more or
less perfectly channeled and furnished with apophyses like ordinary
vertebræ; whereas those of the terminal portion are not channeled, are
almost smooth, and scarcely resemble true vertebræ. A tail, though not
externally visible, is really present in man and the anthropomorphous
apes, and is constructed on exactly the same pattern in both. In the
terminal portion the vertebræ, constituting the _os coccyx_, are quite
rudimentary, being much reduced in size and number. In the basal
portion, the vertebræ are likewise few, are united firmly together,
and are arrested in development; but they have been rendered much
broader and flatter than the corresponding vertebræ in the tails of
other animals; they constitute what Broca calls the accessory sacral
vertebræ. These are of functional importance by supporting certain
internal parts and in other ways; and their modification is directly
connected with the erect or semi-erect attitude of man and the
anthropomorphous apes. This conclusion is the more trustworthy, as
Broca formerly held a different view, which he has now abandoned. The
modification, therefore, of the basal caudal vertebræ in man and the
higher apes may have been effected, directly or indirectly, through
natural selection.
But what are we to say about the rudimentary and variable vertebræ of
the terminal portion of the tail, forming the _os coccyx_? A notion
which has often been, and will no doubt again be ridiculed, namely,
that friction has had something to do with the disappearance of the
external portion of the tail, is not so ridiculous as it at first
appears. Dr. Anderson states that the extremely short tail of _Macacus
brunneus_ is formed of eleven vertebræ, including the imbedded basal
ones. The extremity is tendinous and contains no vertebræ; this is
succeeded by five rudimentary ones, so minute that together they are
only one line and a half in length, and these are permanently bent to
one side in the shape of a hook. The free part of the tail, only a
little above an inch in length, includes only four more small vertebræ.
This short tail is carried erect; but about a quarter of its total
length is doubled on to itself to the left; and this terminal part,
which includes the hook-like portion, serves “to fill up the interspace
between the upper divergent portion of the callosities”; so that the
animal sits on it, and thus renders it rough and callous.
POINTS OF RESEMBLANCE BETWEEN MAN AND MONKEY.
[Descent of
Man, page 150.]
As small unimportant points of resemblance between man and the
_Quadrumana_ 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 our features is manifestly
the same; 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 backward,
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
mustaches. The hair on the head grows to a great length in some species
of Semnopithecus; and in the Bonnet monkey (_Macacus radiatus_) it
radiates from a point on the crown, with a parting down the middle.
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 downward abruptly, and is succeeded by hair so short
and fine 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 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 downward or toward 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 on the back and its direction are adapted to throw off the
rain; even the transverse hairs on the forelegs of a dog may serve for
this end when he is coiled up asleep. Mr. Wallace, who has carefully
studied the habits of the orang, remarks that the convergence of the
hair toward the elbow on the arms of the orang may be explained as
serving to throw off the rain, for this animal during rainy weather
sits with its arms bent, and with the hands clasped round a branch or
over its head. According to Livingstone, the gorilla also “sits in
pelting rain with his hands over his head.” If the above explanation
is correct, as seems probable, the direction of the hair on our own
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.
* * * * *
[Page 152.]
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, etc.--are all necessarily the
result of unbroken inheritance from a common progenitor, or of
subsequent reversion. Many of these resemblances are more probably due
to analogous variation, which follows, as I have elsewhere attempted
to show, from co-descended organisms having a similar constitution, and
having been acted on by like causes inducing similar modifications.
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 this is not certain, as some very distinct American monkeys are
thus characterized.
VARIABILITY OF MAN.
[Descent of
Man, page 26.]
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. 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. 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 1,040 corpses how often each
course prevails. The muscles are eminently variable: thus those of the
foot were found by Professor Turner not to be strictly alike in any two
out of fifty bodies; and in some the deviations were considerable.
He adds that the power of performing the appropriate movements must
have been modified in accordance with the several deviations. Mr.
J. Wood has recorded the occurrence of 295 muscular variations in
thirty-six subjects, and in another set of the same number no less
than 558 variations, those occurring on both sides of the body being
only reckoned 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
Professor Macalister describes no less than twenty distinct variations
in the _palmaris accessorius_.
CAUSES OF VARIABILITY IN DOMESTICATED MAN.
[Descent of
Man, page 28.]
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 to 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 the conditions to which they have
been subjected. In this respect the different races of man resemble
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 civilized nations;
for the members belonging to different grades of rank, and following
different occupations, present a greater range of character than do
the members of barbarous nations. But the uniformity of savages has
often been exaggerated, and in some cases can hardly be said to exist.
It is, nevertheless, an error to speak of man, even if we look only to
the conditions to which he has been exposed, as “far more domesticated”
than any other animal. Some savage races, such as the Australians, are
not exposed to more diversified conditions than are many species which
have a wide range. In another and much more important respect, man
differs widely from any strictly domesticated animal; for his breeding
has never long been controlled, either by methodical or unconscious
selection. No race or body of men has been so completely subjugated
by other men as that certain individuals should be preserved, and
thus unconsciously selected, from somehow excelling in utility 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 and their tall wives. In Sparta, also, a form of selection
was followed, for it was enacted that all children should be examined
shortly after birth; the well-formed and vigorous being preserved, the
others left to perish.
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 parts of the
body are affected in a closely analogous manner.
ACTION OF CHANGED CONDITIONS.
[Page 30.]
This is a most perplexing subject. It can not be denied that changed
conditions produce some, 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 favor 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
organization is rendered in some degree plastic.
In the United States, above one million soldiers, who served in the
late war, were measured, and the States in which they were born and
reared were recorded. 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 life delays
growth, as shown “by the great difference between the statures of
soldiers and sailors at the ages of seventeen and eighteen years.”
Mr. B. A. Gould endeavored 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
the 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, 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 show 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 vigor.”
THE INHERITED EFFECTS OF THE INCREASED AND DIMINISHED USE OF PARTS.
[Descent of
Man, page 32.]
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 to act 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. Different occupations,
habitually followed, lead to changed proportions in various parts of
the body. Thus it was ascertained by the United States commission that
the legs of the sailors employed in the late war were longer by O·217
of an inch than those of the soldiers, though the sailors were on an
average shorter men; while 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. With sailors, the girth of the
neck and the depth of the instep are greater, while the circumference
of the chest, waist, and hips is less, 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 it is probable.
* * * * *
[Page 33.]
In infants, long before birth, the skin on the soles of the feet is
thicker than on any other part of the body; 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 be short-sighted, while men living much out-of-doors, and especially
savages, are generally long-sighted. Short-sight and long-sight
certainly tend to be inherited. The inferiority of Europeans, in
comparison with savages, in eye-sight and in the other senses, is no
doubt the accumulated and transmitted effect of lessened use during
many generations.
* * * * *
[Page 35.]
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 show 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.
REVERSION AS A FACTOR IN THE DEVELOPMENT OF MAN.
[Descent of
Man, page 40.]
In man, the canine teeth are perfectly efficient instruments for
mastication. But their true canine character, as Owen 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
observes, with the canine teeth projecting considerably beyond the
others in the same manner as in the anthropomorphous apes, but in a
less degree. In these cases, open spaces between the teeth in the one
jaw are left for the reception of the canines of the opposite jaw.
An interspace of this kind in a Caffre skull, figured by Wagner, is
surprisingly wide. Considering how few are the ancient skulls which
have been examined, compared to 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.
Of the anthropomorphous apes the males alone 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, of which I have been assured, that women sometimes
have 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 forefathers 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), 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 examined forty
male subjects, and found a muscle, called by him the ischio-pubic,
in nineteen of them; in three others there was a ligament which
represented this muscle; and in the remaining eighteen no trace of it.
In only two out of thirty female subjects was this muscle developed on
both sides, 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 belief in the descent of man from
some lower form the fact is intelligible; 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.
* * * * *
[Page 43.]
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
certain apes in no less than seven of his muscles, 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-colored stripes suddenly reappear on the legs
and shoulders, after an interval of hundreds, or more probably of
thousands, of generations.
REVERSION IN THE HUMAN FAMILY.
[Animals and
Plants, vol.
ii, page 1.]
When the child resembles either grandparent more closely than its
immediate parents, our attention is not much arrested, though in truth
the fact is highly remarkable; but when the child resembles some remote
ancestor or some distant member in a collateral line--and in the last
case we must attribute this to the descent of all the members from a
common progenitor--we feel a just degree of astonishment. When one
parent alone displays some newly-acquired and generally inheritable
character, and the offspring do not inherit it, the cause may lie
in the other parent having the power of prepotent transmission. But
when both parents are similarly characterized, and the child does
not, whatever the cause may be, inherit the character in question,
but resembles its grandparents, we have one of the simplest cases of
reversion. We continually see another and even more simple case of
atavism, though not generally included under this head, namely, when
the son more closely resembles his maternal than his paternal grandsire
in some male attribute, as in any peculiarity in the beard of man, the
horns of the bull, the hackles or comb of the cock, or, as in certain
diseases necessarily confined to the male sex; for, as the mother can
not possess or exhibit such male attributes, the child must inherit
them, through her blood, from his maternal grandsire.
The cases of reversion may be divided into two main classes, which,
however, in some instances, blend into one another; namely, first,
those occurring in a variety or race which has not been crossed, but
has lost by variation some character that it formerly possessed, and
which afterward reappears. The second class includes all cases in which
an individual with some distinguishable character, a race, or species,
has at some former period been crossed, and a character derived from
this cross, after having disappeared during one or several generations,
suddenly reappears.
* * * * *
[Page 21.]
From these facts we may perhaps infer that the degraded state of so
many half-castes is in part due to reversion to a primitive and savage
condition, induced by the act of crossing, even if mainly due to the
unfavorable moral conditions under which they are generally reared.
PREPOTENCE IN THE TRANSMISSION OF CHARACTER.
[Animals and
Plants, vol.
ii, page 40.]
When individuals, belonging to the same family, but distinct enough
to be recognized, or when two well-marked races, or two species, are
crossed, the usual result, as stated in the previous chapter, is, that
the offspring in the first generation are intermediate between their
parents, or resemble one parent in one part and the other parent in
another part. But this is by no means the invariable rule, for in
many cases it is found that certain individuals, races, and species,
are prepotent in transmitting their likeness. This subject has been
ably discussed by Prosper Lucas, but is rendered extremely complex by
the prepotency sometimes running equally in both sexes, and sometimes
more strongly in one sex than in the other; it is likewise complicated
by the presence of secondary sexual characters, which render the
comparison of crossed breeds with their parents difficult.
It would appear that in certain families some one ancestor, and after
him others in the same family, have had great power in transmitting
their likeness through the male line; for we can not otherwise
understand how the same features should so often be transmitted after
marriages with many females, as in the case of the Austrian emperors;
and so it was, according to Niebuhr, with the mental qualities of
certain Roman families. The famous bull Favorite is believed to have
had a prepotent influence on the short-horn race. It has also been
observed with English race-horses that certain mares have generally
transmitted their own character, while other mares of equally pure
blood have allowed the character of the sire to prevail. A famous black
greyhound, Bedlamite, as I hear from Mr. C. M. Brown, “invariably got
all his puppies black, no matter what was the color of the bitch”; but
then Bedlamite “had a preponderance of black in his blood, both on the
sire and dam side.”
NATURAL SELECTION IN THE DEVELOPMENT OF MAN.
[Descent of
Man, page 48.]
Man in the rudest state in which he now exists is the most dominant
animal that has ever appeared on this earth. He has spread more
widely than any other highly organized form; and all others have
yielded before him. He manifestly owes this immense superiority to
his intellectual faculties, to 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. As Mr. Chauncey Wright remarks: “A
psychological analysis of the faculty of language shows that even the
smallest proficiency in it might require more brain-power than the
greatest proficiency in any other direction.” He has invented and is
able to use various weapons, tools, traps, etc., with which he defends
himself, kills or catches prey, and otherwise obtains food. He has made
rafts or canoes for fishing or crossing over to neighboring 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 discovery of fire, probably the greatest ever made by
man, excepting language, dates from before the dawn of history. These
several inventions, by which man in the rudest state has become so
pre-eminent, are the direct results of the development of his powers of
observation, memory, curiosity, imagination, and reason.
* * * * *
[Page 50.]
Archæologists are convinced that an enormous interval of time elapsed
before our ancestors thought of grinding chipped flints into smooth
tools. One can hardly doubt that 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, with sufficient practice, as
far as mechanical skill alone is concerned, make almost anything which
a civilized 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 genus, musical
cadences; but in man the 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 men, and therefore to the best
representatives of our early progenitors, we find that the hands of the
_Quadrumana_ are constructed on the same general pattern as our own,
but are far less perfectly adapted for diversified uses. Their hands
do not serve for locomotion so well as the feet of a dog; as may be
seen in such monkeys as the chimpanzee and orang, which walk on the
outer margins of the palms, or on the knuckles. 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, in the same manner as we do. They can thus also lift 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. In a wild state they break open hard fruits
with stones. Other monkeys open mussel-shells with the two thumbs. With
their fingers they pull out thorns and burs, and hunt for each other’s
parasites. They roll down stones, or throw them at their enemies;
nevertheless, they are clumsy in these various actions, and, as I have
myself seen, are quite unable to throw a stone with precision.
HOW MAN BECAME UPRIGHT.
[Descent of
Man, page 52.]
If it be an advantage to man to stand firmly on his feet and to have
his hands and arms free, of which, from his pre-eminent success in the
battle of life, there can be no doubt, 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 defend themselves with stones or clubs, to attack their prey,
or otherwise to obtain food. The best built 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 the anthropomorphous apes are now actually in an
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, in existing monkeys a manner of progression
intermediate between that of a quadruped and a biped; but, as an
unprejudiced judge insists, the anthropomorphous apes approach in
structure more nearly to the bipedal than to the quadrupedal type.
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 transformed for firm support
and progression, endless other changes of structure would have become
necessary. The pelvis would have to be broadened, the spine peculiarly
curved, and the head fixed in an altered position, all which changes
have been attained by man.
* * * * *
[Page 53.]
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 forefathers
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 or rivals,
they would use their jaws and teeth less and less. In this case, the
jaws, together with the teeth, would become reduced in size, as we may
feel almost sure from innumerable analogous cases.
THE BRAIN ENLARGES AS THE MENTAL FACULTIES DEVELOP.
[Descent of
Man, page 54.]
As the various mental faculties gradually developed themselves the
brain would almost certainly become larger. No one, I presume, doubts
that the large proportion which the size of man’s brain bears to his
body, compared to the same proportion in the gorilla or orang, is
closely connected with his higher mental powers. We meet with closely
analogous facts with insects, for in ants the cerebral ganglia are of
extraordinary dimensions, and in all the _Hymenoptera_ these ganglia
are many times larger than in the less intelligent orders, such as
beetles. 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 notorious, yet their cerebral ganglia are not so
large as the quarter of a small pin’s head. Under this point of view,
the brain of an ant is one of the most marvelous atoms of matter in the
world, perhaps more so than the brain of a man.
* * * * *
[Page 55.]
The gradually increasing weight of the brain and skull in man must
have influenced the development of the supporting spinal column, more
especially while 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 show 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 have become fixed either sideways
or backward, owing to disease, one of the two eyes has changed its
position, and the shape of the skull has been altered apparently by
the pressure of the brain in a new direction. I have shown that with
long-eared rabbits even so trifling a cause as the lopping forward of
one ear drags forward almost every bone of the skull on that side; so
that the bones on the opposite side 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, while
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 on 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 3·15 and the latter 4·3 inches
in length. One of the most marked distinctions in different races of
men is that the skull in some is elongated, and in others rounded; and
here the explanation suggested by the case of the rabbits may hold
good; for Welcker finds that short “men incline more to brachycephaly,
and tall men to dolichocephaly”; 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 understand, to a certain extent, the
means by which the great size and more or less rounded form of the
skull have been acquired by man; and these are characters eminently
distinctive of him in comparison with the lower animals.
NAKEDNESS OF THE SKIN.
[Descent of
Man, page 56.]
Another most conspicuous difference between man and the lower animals
is the nakedness of the skin. Whales and porpoises (_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 than those
on the lowlands. May we then infer that man became divested of hair
from having aboriginally inhabited some tropical land? That the hair
is 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, favors
this inference--on the assumption 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. The
fact, however, 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, is opposed
to the supposition that man became naked through the action of the sun.
* * * * *
[Descent of
Man, page 18.]
The different races differ much in hairiness; and in the individuals
of the same race the hairs are highly variable, not only in abundance,
but likewise in position: thus in some Europeans the shoulders are
quite naked, while in others they bear thick tufts of hair. 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 the fine,
short, and pale-colored hairs on the limbs and other parts of the body
occasionally become developed into “thick-set, long, and rather coarse
dark hairs,” when abnormally nourished near old-standing inflamed
surfaces.
I am informed by Sir James Paget that often several members of a family
have a few hairs in their eyebrows much longer than the others; so
that even this slight peculiarity seems to be inherited. These hairs,
too, seem to have their representatives; for in the chimpanzee, and in
certain species of Macacus, there are scattered hairs of considerable
length rising from the naked skin above the eyes, and corresponding to
our eyebrows; similar long hairs project from the hairy covering of the
superciliary ridges in some baboons.
IS MAN THE MOST HELPLESS OF THE ANIMALS?
[Descent of
Man, page 63.]
It has often been objected to such views as the foregoing, that man is
one of the most helpless and defenseless 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
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
defense, the small strength and speed of man, and his slight power of
discovering food or of avoiding danger by smell. To these deficiencies
there might be added one still more serious, namely, that he can not
climb quickly, and so escape from enemies. The loss of hair would not
have been a great injury to the inhabitants of a warm country. For we
know that the unclothed Fuegians can exist under a wretched climate.
When we compare the defenseless state of man with that of apes, we must
remember that the great canine teeth with which the latter are provided
are possessed in their full development by the males alone, and are
chiefly used by them for fighting with their rivals; yet the females,
which are not thus provided, manage to survive.
In regard to bodily size or strength, we do not know whether man is
descended from some small species, like the chimpanzee, or from one as
powerful as the gorilla; and, therefore, we can not say whether man has
become larger and stronger, or smaller and weaker, than his ancestors.
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 not perhaps have become social; and
this would most effectually have checked the acquirement of the higher
mental qualities--such as sympathy and the love of his fellows. Hence
it might have been an immense advantage to man to have sprung from some
comparatively weak creature.
The small strength and speed of man, his want of natural weapons, etc.,
are more than counterbalanced, firstly, by his intellectual powers,
through which he has formed for himself weapons, tools, etc., though
still remaining in a barbarous state, and, secondly, by his social
qualities, which lead him to give and receive aid from his fellow-men.
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 of races,
that of the Bushmen, maintains itself in Southern Africa, as do the
dwarfed Esquimaux in the Arctic regions. The ancestors 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 they had advanced in
intellect, while gradually losing their brute-like powers, such as that
of climbing trees, etc. But these ancestors would not have been exposed
to any special danger, even if far more helpless and defenseless than
any existing savages, had they inhabited some warm continent or large
island, such as Australia, New Guinea, or Borneo, which is now the
home of the orang. And natural selection arising from the competition
of tribe with tribe, in some such large area as one of these, together
with the inherited effects of habit, would, under favorable conditions,
have sufficed to raise man to his present high position in the organic
scale.
VIII.
MENTAL POWERS OF MAN AND THE LOWER ANIMALS COMPARED.
[Descent of
Man, page 65.]
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 hardly any abstract terms for
common objects or for the affections, with that of the most highly
organized ape. The difference would, no doubt, still remain immense,
even if one of the higher apes had been improved or civilized as
much as a dog has been in comparison with its parent-form, the wolf
or jackal. The Fuegians rank among 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 shown 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 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 uses hardly any
abstract terms, and a Newton or Shakespeare. 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.
* * * * *
[Page 66.]
In what manner the mental powers were first developed in the lowest
organisms is as hopeless an inquiry as how life itself first
originated. These are problems for the distant future, if they are ever
to be solved by man.
FUNDAMENTAL INTUITIONS THE SAME IN MAN AND THE OTHER ANIMALS.
[Page 66.]
As man possesses the same senses as 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 desire possessed by the latter to suck,
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 can
not 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 afterward avoid, we can not 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 animals.
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 adverse 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,
has shown 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
among 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 work.
MAN AND THE LOWER ANIMALS EXCITED BY THE SAME EMOTIONS.
[Page 69.]
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. It
is, I think, impossible to read the account given by Sir E. Tennent, of
the behavior of the female elephants, used as decoys, without admitting
that they intentionally practice deceit, and well know what they are
about. 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, and probably true, anecdotes have been published on
the long-delayed and artful revenge of various animals. The accurate
Rengger and Brehm state that the American and African monkeys which
they kept tame certainly revenged themselves. Sir Andrew Smith, a
zoölogist whose scrupulous accuracy was known to many persons, told me
the following story of which he was himself an eye-witness: At the Cape
of Good Hope an officer had often plagued a certain baboon, and the
animal, seeing him approaching one Sunday for parade, poured water into
a hole and hastily made some thick mud, which he skillfully dashed over
the officer as he passed by, to the amusement of many by-standers. For
long afterward the baboon rejoiced and triumphed whenever he saw his
victim.
* * * * *
[Page 70.]
The love of a dog for his master is notorious; as an old writer
quaintly says, “A dog is the only thing on this earth that luvs you
more than he luvs himself.”
In the agony of death a dog 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 the operation was fully
justified by an increase of our knowledge, or unless he had a heart of
stone, must have felt remorse to the last hour of his life.
* * * * *
[Page 71.]
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 shows that animals not only love, but
have 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 offenses.
In the Zoölogical 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.
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
for 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 Zoölogical Gardens, and the
excitement thus caused was one of the most curious spectacles which I
ever beheld.
ALL ANIMALS POSSESS SOME POWER OF REASONING.
[Page 75.]
Of all the faculties of the human mind, it will, I presume, be admitted
that _reason_ stands at the summit. Only a few persons now 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 unlearned instincts.
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. For instance, 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 which the travelers 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 instinct? This
instinct may 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
an instinct, impelling them not to attack their prey in a close pack,
when on thin ice.
* * * * *
[Page 79.]
Archbishop Sumner formerly maintained that man alone is capable of
progressive improvement. That he is capable of incomparably greater and
more rapid improvement than is any other animal, admits of no dispute;
and this is mainly due to his power of speaking and handing down his
acquired knowledge. 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 a trap. They must learn
caution by seeing their brethren caught or poisoned.
* * * * *
[Page 80.]
Our domestic dogs are descended from wolves and jackals, and though
they may not have gained in cunning, and may have lost in wariness
and suspicion, yet they have progressed in certain moral qualities,
such as in affection, trustworthiness, temper, and probably in general
intelligence.
THE POWER OF ASSOCIATION IN DOG AND SAVAGE.
[Descent of
Man, page 77.]
The savage and the dog have often found water at a low level, and the
coincidence under such circumstances has become associated in their
minds. A cultivated man would perhaps make some general proposition
on the subject; but from all that we know of savages it is extremely
doubtful whether they would do so, and a dog certainly would not.
But a savage, as well as a dog, would search in the same way, though
frequently disappointed; and in both it seems to be equally an act
of reason, whether or not any general proposition on the subject
is consciously placed before the mind. The same would apply to the
elephant and the bear making currents in the air or water. The savage
would certainly neither know nor care by what law the desired movements
were effected; yet his act would be guided by a rude process of
reasoning, as surely as would a philosopher in his longest chain of
deductions. There would no doubt be this difference between him and
one of the higher animals, that he would take notice of much slighter
circumstances and conditions, and would observe any connection between
them after much less experience, and this would be of paramount
importance. I kept a daily record of the actions of one of my infants,
and when he was about eleven months old, and before he could speak a
single word, I was continually struck with the greater quickness with
which all sorts of objects and sounds were associated together in his
mind, compared with that of the most intelligent dogs I ever knew. But
the higher animals differ in exactly the same way in this power of
association from those low in the scale, such as the pike, as well as
in that of drawing inferences and of observation.
THE LOWER ANIMALS PROGRESS IN INTELLIGENCE.
[Page 81.]
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. We have
seen 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. Rengger easily taught an American monkey thus
to break open hard palm-nuts; and afterward, 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 flavor. Another
monkey was taught to open the lid of a large box with a stick, and
afterward 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. The tamed
elephants in India are well known to break off branches of trees and
use them to drive away the flies; and this same act has been observed
in an elephant in a state of nature.
* * * * *
[Page 82.]
The Duke of Argyll 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. This is
no doubt a very important distinction; but there appears to me much
truth in Sir J. Lubbock’s suggestion 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 break the flints on purpose, and not a very
wide step to fashion them rudely. 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 POWER OF ABSTRACTION.
[Page 83.]
If one may judge from various articles which have been published
lately, the greatest stress seems to be laid on the supposed entire
absence in animals of the power of abstraction, or of forming general
concepts. But when a dog sees another dog at a distance, it is often
clear that he perceives that it is a dog in the abstract; for when he
gets nearer his whole manner suddenly changes, if the other dog be a
friend. A recent writer remarks that in all such cases it is a pure
assumption to assert that the mental act is not essentially of the same
nature in the animal as in man. If either refers what he perceives
with his senses to a mental concept, then so do both. When I say to
my terrier, in an eager voice (and I have made the trial many times),
“Hi, hi, where is it?” she at once takes it as a sign that something
is to be hunted, and generally first looks quickly all around, and then
rushes into the nearest thicket, to scent for any game, but, finding
nothing, she looks up into any neighboring tree for a squirrel. Now, do
not these actions clearly show that she had in her mind a general idea
or concept that some animal is to be discovered and hunted?
It may be freely admitted that no animal is self-conscious, if by
this term it is implied that he reflects on such points as whence
he comes or whither he will go, or what is life and death, and so
forth. But how can we feel sure that an old dog with an excellent
memory and some power of imagination, as shown by his dreams, never
reflects on his past pleasures or pains in the chase? And this would
be a form of self-consciousness. On the other hand, as Büchner has
remarked, how little can the hard-worked wife of a degraded Australian
savage, who uses very few abstract words, and can not count above
four, exert her self-consciousness, or reflect on the nature of her
own existence! It is generally admitted that the higher animals
possess memory, attention, association, and even some imagination
and reason. If these powers, which differ much in different animals,
are capable of improvement, there seems no great improbability in
more complex faculties, such as the higher forms of abstraction, and
self-consciousness, etc., having been evolved through the development
and combination of the simpler ones. It has been urged against the
views here maintained that it is impossible to say at what point in the
ascending scale animals become capable of abstraction, etc.; but who
can say at what age this occurs in our young children? We see at least
that such powers are developed in children by imperceptible degrees.
THE EVOLUTION OF LANGUAGE.
[Page 84.]
This faculty (language) 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.” In
Paraguay the _Cebus azaræ_ when excited utters at least six distinct
sounds, which excite in other monkeys similar emotions. 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 learned to
bark in at least four or five distinct tones. Although barking is a
new art, no doubt the wild parent-species 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, as well as
growling; the yelp or howl of despair, as when shut up; the baying at
night; the bark 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. According to Houzeau, who paid particular
attention to the subject, the domestic fowl utters at least a dozen
significant sounds.
The habitual use of 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. 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. That which distinguishes man
from the lower animals is not the understanding of articulate sounds,
for, as every one knows, dogs understand many words and sentences. In
this respect they are at the same stage of development as infants,
between the ages of ten and twelve months, who understand many words
and short sentences, but can not yet utter a single word. It is not the
mere articulation which is our distinguishing character, for parrots
and other birds possess this power. Nor is it the mere capacity of
connecting definite sounds with definite ideas; for it is certain that
some parrots, which have been taught to speak, connect unerringly words
with things, and persons with events. The lower animals differ from man
solely in his almost infinitely larger power of associating together
the most diversified sounds and ideas; and this obviously depends on
the high development of his mental powers.
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 better simile. It certainly is not a true instinct, for
every language has to be learned. 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; while no child has an instinctive
tendency to brew, bake, or write. Moreover, no philologist now supposes
that any language has been deliberately invented; it 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 which sing exert their
power instinctively; but the actual song, and even the call-notes, are
learned from their parents or foster-parents. These sounds, as Daines
Barrington has proved, “are no more innate than language is in man.”
The first attempts to sing “may be compared to the imperfect endeavor
in a child to babble.” The young males continue practicing, 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 learned 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 show that an instinctive tendency to
acquire an art is not peculiar to man.
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 Professor Schleicher, and the celebrated
lectures of Professor Max Müller on the other side, I can not doubt
that language owes its origin to the imitation and modification of
various natural sounds, the voices of other animals, and man’s own
instinctive cries, aided by signs and gestures.
* * * * *
[Page 87.]
It is, therefore, probable that the imitation of musical cries by
articulate sounds may have given rise to words expressive of various
complex emotions. The strong tendency in our nearest allies, the
monkeys, in microcephalous idiots, and in the barbarous races of
mankind, to imitate whatever they hear, deserves notice, as bearing on
the subject of imitation. Since monkeys certainly understand much that
is said to them by man, and, when wild, utter signal-cries of danger
to their fellows; and since fowls give distinct warnings for danger on
the ground, or in the sky from hawks (both, as well as a third cry,
intelligible to dogs), may not some unusually wise ape-like animal have
imitated the growl of a beast of prey, and thus told his fellow-monkeys
the nature of the expected danger? 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.
* * * * *
[Page 89.]
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 only for croaking.
DEVELOPMENT OF LANGUAGES AND SPECIES COMPARED.
[Descent of
Man, page 90.]
The formation of different languages and of distinct species and
the proofs that both have been developed through a gradual process
are curiously parallel. But we can trace the formation of many
words further back than that of species, for we can perceive how
they actually arose from the imitation of various sounds. 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. 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 has well remarked: “A struggle for life
is constantly going on among 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 and fashion may 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 favored 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 civilization 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.” 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, etc., 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 show how easily we may err: a crinoid sometimes
consists of no less than one hundred and fifty thousand pieces of
shell, 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 parts alike, excepting on the opposite sides of the body. He
justly considers the differentiation and specialization of organs
as the test of perfection. So with languages; the most symmetrical
and complex ought not to be ranked above irregular, abbreviated, and
bastardized languages.
THE SENSE OF BEAUTY.
[Descent of
Man, page 92.]
This sense has been declared to be peculiar to man. I refer here only
to the pleasure given by certain colors, forms, and sounds, and which
may fairly be called a sense of the beautiful; with cultivated men
such sensations are, however, intimately associated with complex
ideas and trains of thought. When we behold a male bird elaborately
displaying his graceful plumes or splendid colors before the female,
while other birds, not thus decorated, make no such display, it is
impossible to doubt that she admires the beauty of her male partner.
As women everywhere deck themselves with these plumes, the beauty of
such ornaments can not be disputed. As we shall see later, the nests of
humming-birds and the playing passages of bower-birds are tastefully
ornamented with gayly-colored objects; and this shows that they must
receive some kind of pleasure from the sight of such things. With the
great majority of animals, however, the taste for the beautiful is
confined, as far as we can judge, to the attractions of the opposite
sex. The sweet strains poured forth by many male birds 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 colors, the ornaments, and voices of their
male partners, all the labor and anxiety exhibited by the latter in
displaying their charms before the females would have been thrown away;
and this it is impossible to admit. Why certain bright colors should
excite pleasure can not, I presume, be explained, any more than why
certain flavors and scents are agreeable; but habit has something to do
with the result, for that which is at first unpleasant to our senses,
ultimately becomes pleasant, and habits are inherited.
DEVELOPMENT OF THE EAR FOR MUSIC.
[Descent of
Man, page 568.]
A critic has asked how the ears of man, and he ought to have added
of other animals, could have been adapted by selection so as to
distinguish musical notes. But this question shows some confusion on
the subject; a noise is the sensation resulting from the co-existence
of several aërial “simple vibrations” of various periods, each of
which intermits so frequently that its separate existence can not be
perceived. It is only in the want of continuity of such vibrations,
and in their want of harmony _inter se_, that a noise differs from a
musical note. Thus an ear to be capable of discriminating noises--and
the high importance of this power to all animals is admitted by every
one--must be sensitive to musical notes. We have evidence of this
capacity even low down in the animal scale; thus crustaceans are
provided with auditory hairs of different lengths, which have been seen
to vibrate when the proper musical notes are struck. As stated in a
previous chapter, similar observations have been made on the hairs of
the antennæ of gnats. It has been positively asserted by good observers
that spiders are attracted by music. It is also well known that some
dogs howl when hearing particular tones. Seals apparently appreciate
music, and their fondness for it “was well known to the ancients, and
is often taken advantage of by the hunters at the present day.”
Therefore, as far as the mere perception of musical notes is concerned,
there seems no special difficulty in the case of man or of any other
animal.
But if it be further asked why musical tones in a certain order and
rhythm give man and other animals pleasure, we can no more give the
reason than for the pleasantness of certain tastes and smells. That
they do give pleasure of some kind to animals we may infer from
their being produced during the season of courtship by many insects,
spiders, fishes, amphibians, and birds; for, unless the females were
able to appreciate such sounds and were excited or charmed by them,
the persevering efforts of the males and the complex structures often
possessed by them alone would be useless; and this it is impossible to
believe.
IX.
DEVELOPMENT OF THE MORAL SENSE.
[Descent of
Man, page 97.]
I fully subscribe to the judgment of those writers 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 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.
* * * * *
[Page 111.]
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 Newfoundland dog drags a child out of the water, or 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.
FROM THE SOCIAL INSTINCTS TO THE MORAL SENSE.
[Page 98.]
The following proposition seems to me in a high degree
probable--namely, that any animal whatever, endowed with well-marked
social instincts, the parental and filial affections being here
included, would inevitably acquire a moral sense or conscience, as
soon as its intellectual powers had become as well, 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, or even misery, 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 community could be
expressed, the common opinion how each member ought to act for the
public good would naturally become in a paramount degree the guide
to action. But it should be borne in mind that, however great weight
we may attribute to public opinion, our regard for the approbation
and disapprobation of our fellows depends on sympathy, which, as we
shall see, forms an essential part of the social instinct, and is,
indeed, its foundation-stone. _Lastly_, habit in the individual would
ultimately play a very important part in guiding the conduct of each
member; for the social instinct, together with sympathy, is, like any
other instinct, greatly strengthened by habit, and so consequently
would be 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 gain in our supposed case, as it appears to me, some feeling of
right or 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 as to which impulse should be followed; and satisfaction,
dissatisfaction, or even misery 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, and the other ought not; the one would
have been right and the other wrong.
HUMAN SYMPATHY AMONG ANIMALS.
[Page 102.]
Who can say what cows feel when they surround and stare intently on a
dying or dead companion? Apparently, however, as Houzeau remarks, they
feel no pity. 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 Feejeeans, who, when their parents get
old, or fall ill, bury them alive.
* * * * *
[Page 103.]
Several years ago a keeper at the Zoölogical Gardens showed me some
deep and scarcely healed wounds on the nape of his own neck, inflicted
on him, while 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 in peril, he rushed to the
rescue, and by screams and bites so distracted the baboon that the man
was able to escape, after, as the surgeon thought, running great risk
of his life.
Besides love and sympathy, animals exhibit other qualities connected
with the social instincts, which in us would be called moral; and I
agree with Agassiz that dogs possess something very like a conscience.
* * * * *
[Page 107.]
With mankind, selfishness, experience, and imitation, probably add,
as Mr. Bain has shown, 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 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 one
another, 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.
It is, however, impossible to decide in many cases 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 of sentinels to warn the community of danger
can hardly have been the indirect result of any of these faculties; 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 selection.
THE LOVE OF APPROBATION.
[Page 109.]
Although man 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 fellows; for, as Mr. Bain has
clearly shown, 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 influenced in the highest
degree 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
some of his best actions; but his actions are in a higher degree
determined by the expressed wishes and judgment of his fellow-men, and
unfortunately very often by his own strong selfish desires. But as
love, sympathy, and self-command become strengthened by habit, and as
the power of reasoning becomes clearer, so that man can value justly
the judgments of his fellows, he will feel himself impelled, apart from
any transitory pleasure or pain, to certain lines of conduct. He might
then declare--not that any barbarian or uncultivated man could thus
think--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.
FELLOW-FEELING FOR OUR FELLOW-ANIMALS.
[Page 123.]
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 toward their pets. How little
the old Romans knew of it is shown 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
honored and practiced by some few men, it spreads through instruction
and example to the young, and eventually becomes incorporated in public
opinion.
The highest possible stage in moral culture is when we recognize 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.” 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.”
* * * * *
[Page 125.]
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 triumphant.
DEVELOPMENT OF THE GOLDEN RULE.
[Page 125.]
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
colored 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, certainly is 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, etc., 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 could be proved
that certain high mental powers, such as the formation of general
concepts, self-consciousness, etc., were absolutely peculiar to man,
which seems extremely doubtful, it is not improbable that these
qualities are merely the incidental results of other highly-advanced
intellectual faculties; and these again mainly the result of the
continued use of a perfect 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 can not answer; nor can we answer in
regard to the ascending organic scale. The half-art, 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 spiritual
agencies naturally follows from other mental powers. The moral sense
perhaps affords the best and highest distinction between man and the
lower animals; but I need say nothing on this head, as I have so lately
endeavored to show that the social instincts--the prime principle of
man’s moral constitution--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.
REGRET PECULIAR TO MAN, AND WHY.
[Descent of
Man, page 112.]
Why does man regret, even though trying to banish 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, can not avoid
reflection: past impressions and images are incessantly and clearly
passing through his mind. 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
again in their company. So it is with ourselves. Even when we are quite
alone, how often do we think with pleasure or pain of what others think
of us--of their imagined approbation or disapprobation!--and this all
follows from sympathy, a fundamental element of the social instincts.
A man who possessed no trace of such instincts 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.
REMORSE EXPLAINED.
[Page 114.]
Several critics have objected that though some slight regret or
repentance may be explained by the view advocated in this chapter, it
is impossible thus to account for the soul-shaking feeling of remorse.
But I can see little force in this objection. My critics do not define
what they mean by remorse, and I can find no definition implying more
than an overwhelming sense of repentance. Remorse seems to bear the
same relation to repentance as rage does to anger, or agony to pain. It
is far from strange that an instinct so strong and so generally admired
as maternal love should, if disobeyed, lead to the deepest misery, as
soon as the impression of the past cause of disobedience is weakened.
Even when an action is opposed to no special instinct, merely to know
that our friends and equals despise us for it is enough to cause great
misery. Who can doubt that the refusal to fight a duel through fear
has caused many men an agony of shame? Many a Hindoo, it is said, has
been stirred to the bottom of his soul by having partaken of unclean
food. Here is another case of what must, I think, be called remorse.
Dr. Landor acted as a magistrate in West Australia, and relates that a
native on his farm, after losing one of his wives from disease, came
and said that “he was going to a distant tribe to spear a woman, to
satisfy his sense of duty to his wife.” I told him that if he did so
I would send him to prison for life. He remained about the farm for
some months, but got exceedingly thin, and complained that he could
not rest or eat, that his wife’s spirit was haunting him because he
had not taken a life for hers. I was inexorable, and assured him that
nothing should save him if he did. Nevertheless, the man disappeared
for more than a year, and then returned in high condition; and his
other wife told Dr. Landor that her husband had taken the life of a
woman belonging to a distant tribe; but it was impossible to obtain
legal evidence of the act. The breach of a rule held sacred by the
tribe will thus, as it seems, give rise to the deepest feelings, and
this quite apart from the social instincts, excepting in so far as the
rule is grounded on the judgment of the community. How so many strange
superstitions have arisen throughout the world we know not; nor can we
tell how some real and great crimes, such as incest, have come to be
held in an abhorrence (which is not, however, quite universal) by the
lowest savages. It is even doubtful whether in some tribes incest would
be looked on with greater horror than would the marriage of a man with
a woman bearing the same name, though not a relation. “To violate this
law is a crime which the Australians hold in the greatest abhorrence,
in this agreeing exactly with certain tribes of North America. When the
question is put in either district, is it worse to kill a girl of a
foreign tribe, or to marry a girl of one’s own, an answer just opposite
to ours would be given without hesitation.” We may, therefore, reject
the belief, lately insisted on by some writers, that the abhorrence of
incest is due to our possessing a special God-implanted conscience.
DEVELOPMENT OF SELF-CONTROL.
[Page 115.]
Man, prompted by his conscience, will through long habit acquire such
perfect self-command, that his desires and passions will at last
yield instantly and without a struggle to his social sympathies and
instincts, including his feeling for the judgment of his fellows. 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 impulses. The imperious word _ought_ seems merely
to imply the consciousness of the existence of a rule of conduct,
however it may have originated. Formerly it must have been often
vehemently urged that an insulted gentleman _ought_ to fight a duel. We
even say that a pointer _ought_ to point, and a retriever to retrieve
game. If they fail to do so, 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, when recalled to mind, as strong as, or stronger
than, the social instinct, a man 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 realized.
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 and the judgment of others, then he is
essentially a bad man; 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 own.
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 supervenes.
VARIABILITY OF CONSCIENCE.
[Page 117.]
Suicide during former times was not generally considered as a crime,
but rather, from the courage displayed, as an honorable act; and it
is still practiced by some semi-civilized and savage nations without
reproach, for it does not obviously concern others of the tribe. It
has been recorded that an Indian thug conscientiously regretted that
he had not robbed and strangled as many travelers as did his father
before him. In a rude state of civilization the robbery of strangers
is, indeed, generally considered as honorable.
Slavery, although in some way beneficial during ancient times, is a
great crime; yet it was not so regarded until quite recently, even by
the most civilized nations. And this was especially the case because
the slaves belonged in general to a race different from that of their
masters. As barbarians do not regard the opinion of their women, wives
are commonly treated like slaves.
* * * * *
[Page 122.]
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 minds of men; but it is worthy of remark that a belief constantly
inculcated during the early years of life, while 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; nor, again, why similar differences prevail even
among highly civilized nations. Knowing how firmly fixed many strange
customs and superstitions have become, we need feel no surprise that
the self-regarding virtues, supported as they are by reason, should now
appear to us so natural as to be thought innate, although they were not
valued by man in his early condition.
* * * * *
[Page 121.]
The wishes and opinions of the members of the same community, expressed
at first orally, but later by writing also, either form the sole guides
of our conduct, or greatly re-enforce the social instincts; such
opinions, however, have sometimes a tendency directly opposed to these
instincts. This latter fact is well exemplified by the _law of honor_,
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 recognize 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.
PROGRESS NOT AN INVARIABLE RULE.
[Descent of
Man, page 140.]
We must remember that progress is no invariable rule. It is very
difficult to say why one civilized nation rises, becomes more
powerful, and spreads more widely, than another; or why the same
nation progresses more quickly 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 appears to have little influence, except so far as vigor of
body leads to vigor of mind.
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, ought, if the
power of natural selection were real, to have risen 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 toward continued
development in mind and body. But development of all kinds depends
on many concurrent favorable circumstances. Natural selection acts
only tentatively. 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.” The Western nations of Europe, who now so immeasurably
surpass their former savage progenitors, and stand at the summit
of civilization, owe little or none of their superiority to direct
inheritance from the old Greeks, though they owe much to the written
works of that wonderful people.
* * * * *
[Page 142.]
The remarkable success of the English as colonists, compared to other
European nations, has been ascribed to their “daring and persistent
energy”; a result which is well illustrated by comparing the progress
of the Canadians of English and French extraction; 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, is the result of natural selection; for the
more energetic, restless, and courageous men from all parts of Europe
have emigrated during the last ten or twelve generations to that great
country, and have there succeeded best.
ALL CIVILIZED NATIONS ARE THE DESCENDANTS OF BARBARIANS.
[Page 144.]
The evidence that all civilized 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, etc.;
and, on the other side, of proofs that savages are independently able
to raise themselves a few steps in the scale of civilization, and
have actually thus risen. The evidence on the first head is extremely
curious, but can not be here given: I refer to such cases as that of
the art of enumeration, which, as Mr. Tylor clearly shows by reference
to 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, where, after the V, which is supposed to be an
abbreviated picture of a human hand, we pass on to VI, etc., when the
other hand no doubt was used. So again, “when we speak of threescore
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.” 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, for letters are rudiments of pictorial
representations. It is hardly possible to read Mr. McLennan’s work and
not admit that almost all civilized nations still retain 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 shown by the law of battle and other
customs of which vestiges 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 shown 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 in use among savages in various parts of the world,
it can not be doubted that these have nearly all been independent
discoveries, excepting perhaps the art of making fire. 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 abroad; many native plants
were there cultivated, and a few native animals domesticated. We
should bear in mind that, judging from the small influence of most
missionaries, a wandering crew from some semi-civilized land, if washed
to the shores of America, would not 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
countries, which include nearly the whole civilized world, were
once in a barbarous condition. To believe that man was aboriginally
civilized 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.
“THE ENNOBLING BELIEF IN GOD.”
[Descent of
Man, page 93.]
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 travelers,
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. 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 some of the highest intellects that have
ever existed.
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 universal with the less civilized 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
crave to understand what was passing around him, and would have vaguely
speculated on his own existence. As Mr. McLennan 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 also probable, as Mr. Tylor
has shown, 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.” But, until the faculties
of imagination, curiosity, reason, etc., 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 that 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 feel. 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 practiced 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 that in good ones.
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, 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 behavior 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 toward their fellows. In the
latter case, the transports of joy appear to be somewhat less, and the
sense of equality is shown in every action. Professor Braubach 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 fetichism, 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, etc.--yet it is well
occasionally to reflect on these superstitions, for they show us what
an infinite debt of gratitude we owe to the improvement of our reason,
to science, and to our accumulated knowledge. 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.
X.
THE GENEALOGY OF MAN.
[Descent of
Man, page 146.]
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. Spiritual powers can not be compared or
classed by the naturalist: but he may endeavor to show, 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
than, though of a somewhat different kind from, that between man and
the highest mammal. The female coccus, while young, attaches itself
by its proboscis to a plant; sucks the sap, but never moves again; is
fertilized and lays eggs; and this is its whole history. On the other
hand, to describe the habits and mental powers of worker-ants would
require, as Pierre Huber has shown, a large volume; I may, however,
briefly specify a few points. Ants certainly communicate information
to each other, and several unite for the same work, or for games of
play. They recognize their fellow-ants after months of absence, and
feel sympathy for each other. They build great edifices, keep them
clean, close the doors in the evening, and post sentries. They make
roads as well as tunnels under rivers, and temporary bridges over
them, by clinging together. They collect food for the community, and,
when an object, too large for entrance, is brought to the nest, they
enlarge the door, and afterward build it up again. They store up
seeds, of which they prevent the germination, and which, if damp, are
brought up to the surface to dry. They keep aphides and other insects
as milch-cows. They go out to battle in regular bands, and freely
sacrifice their lives for the common weal. They emigrate according to
a preconcerted plan. They capture slaves. 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 these insects in distinct classes, much less in distinct
kingdoms. No doubt the difference is bridged over by other insects; and
this is not the case with man and the higher apes. But we have every
reason to believe that the breaks in the series are simply the results
of many forms having become extinct.
MAN A SUB-ORDER.
[Page 149.]
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, etc. 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: for, in the first place, we must
bear in mind the comparative insignificance for classification of the
great development of the brain in man, and 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 most systems, from that of Cuvier to the most recent one
by Mr. Flower, 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.
* * * * *
[Page 152.]
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, from 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 stock, 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, while 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. 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 of genealogy. To attach much weight to the few but
strong differences is the most obvious and perhaps the safest course,
though it appears more correct to pay great attention to the many small
resemblances, as giving a truly natural classification.
In forming 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 Catarrhine group, or Old World
monkeys, all of which are characterized (as their name expresses)
by the peculiar structure of their nostrils, and by having four
premolars in each jaw; and into the Platyrrhine group or New World
monkeys (including two very distinct sub-groups), all of which are
characterized 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 Catarrhine
or Old World division; nor does he resemble the Platyrrhines more
closely than the Catarrhines in any characters, excepting in a few
of not much importance and apparently of an adaptive nature. It is,
therefore, against all probability that some New World species should
have formerly varied and 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 Catarrhine division.
* * * * *
[Page 155.]
And, as man from a genealogical point of view belongs to the Catarrhine
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. 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.
THE BIRTHPLACE OF MAN.
[Page 155.]
We are naturally led to inquire, where was the birthplace of man at
that stage of descent when our progenitors diverged from the Catarrhine
stock? The fact that they belonged to this stock clearly shows 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 two or three anthropomorphous apes,
one the Dryopithecus of Lartet, nearly as large as a man, and closely
allied to Hylobates, existed in Europe during the Miocene age; 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 was, when man
first lost his hairy covering, he probably inhabited a hot country;
a circumstance favorable for the 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 Catarrhine stock; but it may have
occurred at an epoch as remote as the Eocene[A] period; for that the
higher apes have diverged from the lower apes as early as the Upper
Miocene period is shown 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 be modified under favorable circumstances; 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 some of the co-descendants of the same species may be not at all,
some a little, and some greatly changed, all within the same period.
Thus it may have been with man, who has undergone a great amount of
modification in certain characters in comparison with the higher apes.
[A] EOCENE.--The earliest of the three divisions of the
Tertiary epoch of geologists. Rocks of this age contain
a small proportion of shells identical with species now
living.
The great break in the organic chain between man and his nearest
allies, which can not 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, from general reasons, believe in the
general principle of evolution. Breaks often 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 all other
mammals. But 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 civilized races of man will almost certainly
exterminate, and replace, the savage races throughout the world. At the
same time the anthropomorphous apes, as Professor Schaaffhausen has
remarked, will no doubt be exterminated. The break between man and his
nearest allies will then be wider, for it will intervene between man in
a more civilized state, as we may hope, even than the Caucasian, and
some ape as low as a baboon, instead of as now between the negro or
Australian and the gorilla.
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 reads Sir C. Lyell’s discussion, where he shows that in all the
vertebrate classes the discovery of fossil remains has been a very 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 geologists.
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; but as a most capable judge, Mr. Parker, has
remarked, we have good reason to believe that no true bird or reptile
intervenes in the direct line of descent.
ORIGIN OF THE VERTEBRATA.
[Page 158.]
[The Vertebrata are defined as “the highest division of the animal
kingdom, so called from the presence in most cases of a backbone
composed of numerous joints or _vertebræ_, which constitutes the center
of the skeleton and at the same time supports and protects the central
parts of the nervous system.”]
Every evolutionist will admit that the five great vertebrate classes,
namely, mammals, birds, reptiles, amphibians, and fishes, are 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
organized, and appeared before the others, we may conclude that all
the members of the vertebrate kingdom are derived from some fish-like
animal. The belief that animals so distinct as a monkey, an elephant, a
hummingbird, a snake, a frog, and a fish, etc., 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 binding closely 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 several of the great vertebrate
classes more or less closely. We have seen that the Ornithorhynchus
graduates toward reptiles; and Professor Huxley has discovered, and is
confirmed by Mr. Cope and others, that the Dinosaurians are in many
important characters intermediate between certain reptiles and certain
birds--the birds referred to being the ostrich-tribe (itself evidently
a widely-diffused remnant of a larger group) and the Archeopteryx, that
strange Secondary bird, with a long, lizard-like tail. Again, according
to Professor Owen, the Ichthyosaurians--great sea-lizards furnished
with paddles--present many affinities with fishes, or rather, according
to Huxley, with amphibians; a class which, 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 generalized type, that is, they
presented diversified affinities with other groups of organisms. The
Lepidosiren is also so closely allied to amphibians and fishes that
naturalists long disputed in which of these two classes to rank it;
it, and also some few Ganoid fishes have been preserved from utter
extinction by inhabiting rivers, which are harbors of refuge, and are
related to the great waters of the ocean in the same way that islands
are to continents.
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, etc., so that it was classed by the older
naturalists among the worms. Many years ago Professor 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
among the Vermes or worms. Their larvæ somewhat resemble tadpoles in
shape, and have the power of swimming freely about. M. Kovalevsky
has lately observed 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; and in this he has been since
confirmed by Professor Kupffer.
* * * * *
[Page 160.]
Thus, if we may rely on embryology, ever the safest guide in
classification, it seems that we have at last gained a clew to
the source whence the Vertebrata were derived. We should then 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.
FROM NO BONE TO BACKBONE.
[Page 164.]
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, resembling the larvæ of existing Ascidians.
These animals probably gave rise to a group of fishes, as lowly
organized 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 connect mammals with reptiles in a slight degree. 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 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 very 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 willfully close our eyes, we may, with our present knowledge,
approximately recognize 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 unbiased mind can study any
living creature, however humble, without being struck with enthusiasm
at its marvelous structure and properties.
DOES MANKIND CONSIST OF SEVERAL SPECIES?
[Descent of
Man, page 176.]
The question whether mankind consists of one or several species has of
late years been much discussed by anthropologists, who are divided into
the two schools of monogenists and polygenists. Those who do not admit
the principle of evolution must look at species as separate creations,
or as in some manner as distinct entities; and they must decide what
forms of man they will consider as species by the analogy of the method
commonly pursued in ranking other organic beings as species. But it
is a hopeless endeavor to decide this point, until some definition of
the term “species” is generally accepted; and the definition must not
include an indeterminate element 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, 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 respectively in North America and Europe, should
be ranked as species or geographical races; and the like holds true of
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 majority of rising men, will
feel no doubt that all the races of man are descended from a single
primitive stock; whether or not they may think fit to designate the
races as distinct species, for the sake of expressing their amount of
difference. With our domestic animals, the question whether the various
races have arisen from one or more species is somewhat different.
Although it may be admitted that all the races, as well as all the
natural species within the same genus, have sprung from the same
primitive stock, yet it is a fit subject for discussion whether all the
domestic races of the dog, for instance, have acquired their present
amount of difference since some one species was first domesticated by
man; or whether they owe some of their characters to inheritance from
distinct species which had already been differentiated in a state of
nature. With man no such question can arise, for he can not be said to
have been domesticated at any particular period.
During an early stage in the divergence of the races of man from a
common stock, the differences between the races and their number
must have been small; consequently, as far as their distinguishing
characters are concerned, they then had less claim to rank as distinct
species than the existing so-called races. Nevertheless, so arbitrary
is the term of species, that such early races would, perhaps, have been
ranked by some naturalists as distinct species, if their differences,
although extremely slight, had been more constant than they are at
present, and had not graduated into each other.
THE RACES GRADUATE INTO EACH OTHER.
[Page 174.]
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
animal, and yet there is the greatest possible diversity among capable
judges whether he should be classed as a single species or race, or as
two (Virey), as three (Jacqninot), 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. This diversity
of judgment does not prove that the races ought not to be ranked as
species, but it shows 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 under a single species; for he will say to
himself that he has no right to give names to objects which he can
not define. Cases of this kind occur in the order which includes man,
namely, in certain genera of monkeys; while 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 usually be ranked as mere varieties or races; and this course has
been followed by most naturalists with respect to the races of man.
WAS THE FIRST MAN A SPEAKING ANIMAL?
[Page 180.]
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 but few arts, and those 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 more appropriate. Finally, we may conclude that, when
the principle of evolution is generally accepted, as it surely will be
before long, the dispute between the monogenists and the polygenists
will die a silent and unobserved death.
THE THEORY OF A SINGLE PAIR.
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 by carefully matching the
varying offspring from a single pair, or even from a single individual
possessing some new character; 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 ones were
habitually preferred, we may feel sure that two distinct sub-breeds
would be produced in the course of time, without any one pair having
been separated and bred from in either country. Many races have been
thus formed, and their manner of formation is closely analogous to
that of natural species. We know, also, that the horses taken to the
Falkland Islands have, during successive generations, become smaller
and weaker, while 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 such cases are not 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.
CIVILIZED OUT OF EXISTENCE.
[Descent of
Man, page 183.]
When Tasmania was first colonized the natives were roughly estimated
by some at seven thousand and by others at twenty thousand. Their
number was soon greatly reduced, chiefly by fighting with the English
and with each other. After the famous hunt by all the colonists, when
the remaining natives delivered themselves up to the government, they
consisted only of one hundred and twenty individuals, who were in 1832
transported to Flinders Island. This island, situated between Tasmania
and Australia, is forty miles long, and from twelve to eighteen
miles broad: it seems healthy, and the natives were well treated.
Nevertheless, they suffered greatly in health. In 1834 they consisted
(Bonwick, p. 250) of forty-seven adult males, forty-eight adult
females, and sixteen children, or in all of one hundred and eleven
souls. In 1835 only one hundred were left. As they continued rapidly to
decrease, and as they themselves thought that they should not perish
so quickly elsewhere, they were removed in 1847 to Oyster Cove in the
southern part of Tasmania. They then consisted (December 20, 1847) of
fourteen men, twenty-two women, and ten children. But the change of
site did no good. Disease and death still pursued them, and in 1864
one man (who died in 1869) and three elderly women alone survived.
The infertility of the women is even a more remarkable fact than the
liability of all to ill-health and death. At the time when only nine
women were left at Oyster Cove, they told Mr. Bonwick (p. 386), that
only two had ever borne children: and these two had together produced
only three children!
With respect to the cause of this extraordinary state of things,
Dr. Story remarks that death followed the attempts to civilize
the natives. “If left to themselves to roam as they were wont and
undisturbed, they would have reared more children, and there would have
been less mortality.” Another careful observer of the natives, Mr.
Davis, remarks: “The births have been few and the deaths numerous. This
may have been in a great measure owing to their change of living and
food; but more so to their banishment from the mainland of Van Diemen’s
Land, and consequent depression of spirits” (Bonwick, pp. 388, 390).
* * * * *
[Page 191.]
Although the gradual decrease and ultimate extinction of the races of
man is a highly complex problem, depending on many causes which differ
in different places and at different times, it is the same 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 afterward 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, now almost exterminated by the European rat. Though the difficulty
is great to our imagination, and really great, if we wish to ascertain
the precise causes and their manner of action, it 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 checked in various ways; so
that, if any new check, even a slight one, be superadded, the race will
surely decrease in number; and decreasing numbers will sooner or later
lead to extinction; the end, in most cases, being promptly determined
by the inroads of conquering tribes.
XI.
SEXUAL SELECTION AS AN AGENCY TO ACCOUNT FOR THE DIFFERENCES BETWEEN
THE RACES OF MAN.
[Descent of
Man, page 198.]
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 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 only say, in our ignorance, 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 variations come under the provisional class, alluded to in our
second chapter, which for the want of a better term are often called
spontaneous. Nor do I pretend that the effects of sexual selection
can be indicated with scientific precision; but it can be shown that
it would be an inexplicable fact if man had not been modified by this
agency, which appears to have acted powerfully on innumerable animals.
It can further be shown that the differences between the races of
man, as in color, hairiness, form of features, etc., are of a kind
which might have been expected to come under the influence of sexual
selection.
STRUGGLE OF THE MALES FOR THE POSSESSION OF THE FEMALES.
[Descent of
Man, page 213.]
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 their beaten and less attractive
rivals. Unless this result does follow, the characters which give 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 (except where polygamy
prevails) ultimately find females, and leave as many offspring, as 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 are well developed,
the males considerably exceeded the females in number; but this is not
by any means always true. 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 proportion 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 carefully attended to the habits
of birds during many years. There can also be no doubt that the most
vigorous, best-nourished, and earliest breeders would on an average
succeed in rearing the largest number of fine offspring. The males,
as we have seen, are generally ready to breed before the females; the
strongest, and with some species the best armed of the males, drive
away the weaker; and the former would then unite with the more vigorous
and better-nourished females, because they are the first to breed. Such
vigorous pairs would surely rear a larger number of offspring than the
retarded females, which would be compelled to unite with the conquered
and less powerful males, supposing the sexes to be numerically equal;
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 weapons.
COURTSHIP AMONG THE LOWER ANIMALS.
[Page 214.]
But in very many cases the males which conquer their rivals do not
obtain possession of the females, independently of the choice 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
that they would at the same time prefer the more vigorous and lively
males, and this has in some cases been confirmed by actual observation.
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. Both sexes,
therefore, of such early pairs would, as above explained, have an
advantage over others in rearing offspring; 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 her
in providing for the young. The same principles would apply if each
sex preferred and selected certain individuals of the opposite sex;
supposing that they selected not only the more attractive but likewise
the more vigorous individuals.
WHY THE MALE PLAYS THE MORE ACTIVE PART IN COURTING.
[Page 222.]
We are naturally led to inquire why the male, in so many and such
distinct classes, has become 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 each sex searched for
the other; but why should the male almost always be the seeker? The
ovules of plants after fertilization have to be nourished for a time;
hence the pollen is necessarily brought to the female organs--being
placed on the stigma by means of insects or the wind, or by the
spontaneous movements of the stamens; and, in the _Algæ_, etc., by the
locomotive power of the antherozoöids. With lowly-organized aquatic
animals, permanently affixed to the same spot, and having their sexes
separate, the male element is invariably brought to the female; and
of this we can see the reason, for even if the ova were detached
before fertilization, and did not require subsequent nourishment or
protection, there would yet be greater difficulty in transporting them
than the male element, because, being larger than the latter, they are
produced in far smaller numbers. So that many of the lower animals
are, in this respect, analogous with plants. The males of affixed and
aquatic animals, having been led to emit their fertilizing element in
this way, it is natural that any of their descendants, which rose in
the scale and became locomotive, should retain the same habit; and they
would approach the female as closely as possible, in order not to risk
the loss of the fertilizing element in a long passage of it through
the water. With some few of the lower animals, the females alone are
fixed, and the males of these must be the seekers. But it is difficult
to understand why the males of species, of which the progenitors
were primordially free, should invariably have acquired the habit of
approaching the females, instead of being approached by them. But, in
all cases, in order that the males should seek efficiently, it would
be necessary that they should be endowed with strong passions; and the
acquirement of such passions would naturally follow from the more eager
leaving a larger number of offspring than the less eager.
TRANSMISSION OF SEXUAL CHARACTERISTICS.
[Page 232.]
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 can not even
conjecture why, with certain sub-breeds of the pigeon, black striæ,
though transmitted through the female, should be developed in the
male alone, while every other character is equally transferred to
both sexes. Why, again, with cats, the tortoise-shell color should,
with rare exceptions, be developed in the female alone. The very same
character, such as deficient or supernumerary digits, color-blindness,
etc., 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 through the same sex.
Although we are thus ignorant, the two following rules seem often
to hold good: that variations which first appear in either sex at a
late period of life tend to be developed in the same sex alone; while
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.
* * * * *
[Page 233.]
An excellent case for investigation is afforded by the deer family.
In all the species, but one, the horns are developed only in the
males, though certainly transmitted through the females, and capable
of abnormal development in them. 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 are mature, and have come to differ much in constitution.
In all the other species the horns ought to appear later in life,
which would lead 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, twelve, or even more months in the stags of
the six other and larger species. But with the reindeer the case is
widely different; for, as I hear from Professor Nilsson, who kindly
made special inquiries 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 likewise common
to both sexes in this one species alone.
* * * * *
[Page 239.]
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 bear horns, in comparison
with their much later growth in the other species in which the male
alone bears horns--we may conclude that one, 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, while the sexes differ but little
in constitution. It appears, however, that some difference must exist
between the sexes even during a very early embryonic period, for
characters developed at this age not rarely become attached to one sex.
AN OBJECTION ANSWERED.
[Descent of
Man, page 495.]
Several writers have objected to the whole theory of sexual selection,
by assuming that with animals and savages the taste of the female for
certain colors or other ornaments would not remain constant for many
generations; that first one color and then another would be admired,
and consequently that no permanent effect could be produced. We may
admit that taste is fluctuating, but it is not quite arbitrary. It
depends much on habit, as we see in mankind; and we may infer that
this would hold good with birds and other animals. Even in our own
dress, the general character lasts long, and the changes are to a
certain extent graduated. Abundant evidence will be given in two
places in a future chapter, that savages of many races have admired
for many generations the same cicatrices on the skin, the same
hideously perforated lips, nostrils, or ears, distorted heads, etc.;
and these deformities present some analogy to the natural ornaments
of various animals. Nevertheless, with savages such fashions do not
endure forever, as we may infer from the differences in this respect
between allied tribes on the same continent. So again the raisers of
fancy animals certainly have admired for many generations and still
admire the same breeds; they earnestly desire slight changes, which are
considered as improvements, but any great or sudden change is looked
at as the greatest blemish. With birds in a state of nature we have
no reason to suppose that they would admire an entirely new style of
coloration, even if great and sudden variation often occurred, which is
far from being the case. We know that dovecot pigeons do not willingly
associate with the variously colored fancy breeds; that albino birds do
not commonly get partners in marriage; and that the black ravens of the
Feroe Islands chase away their piebald brethren. But this dislike of
a sudden change would not preclude their appreciating slight changes,
any more than it does in the case of man. Hence with respect to taste,
which depends on many elements, but partly on habit and partly on a
love of novelty, there seems no improbability in animals admiring for
a very long period the same general style of ornamentation or other
attractions, and yet appreciating slight changes in colors, form, or
sound.
DIFFERENCE BETWEEN THE SEXES CREATED BY SEXUAL SELECTION.
[Page 563.]
There can be little doubt that the greater size and strength of man,
in comparison with woman, together with his broader shoulders, more
developed muscles, rugged outline of body, his greater courage and
pugnacity, are all due in chief part to inheritance from his half-human
male ancestors. These characters would, however, have been preserved or
even augmented during the long ages of man’s savagery, by the success
of the strongest and boldest men, both in the general struggle for life
and in their contest for wives; a success which would have insured
their leaving a more numerous progeny than their less favored brethren.
It is not probable that the greater strength of man was primarily
acquired through the inherited effects of his having worked harder than
woman for his own subsistence and that of his family; for the women in
all barbarous nations are compelled to work at least as hard as the
men. With civilized people the arbitrament of battle for the possession
of the women has long ceased; on the other hand, the men, as a general
rule, have to work harder than the women for their joint subsistence,
and thus their greater strength will have been kept up.
* * * * *
With respect to differences of this nature between man and woman, it
is probable that sexual selection has played a highly important part.
I am aware that some writers doubt whether there is any such inherent
difference; but this is at least probable from the analogy of the
lower animals which present other secondary sexual characters. No
one disputes that the bull differs in disposition from the cow, the
wild-boar from the sow, the stallion from the mare, and, as is well
known to the keepers of menageries, the males of the larger apes from
the females. Woman seems to differ from man in mental disposition,
chiefly in her greater tenderness and less selfishness; and this holds
good even with savages, as shown by a well-known passage in Mungo
Park’s “Travels,” and by statements made by many other travelers.
Woman, owing to her maternal instincts, displays these qualities toward
her infants in an eminent degree; therefore it is likely that she
would often extend them toward her fellow-creatures. Man is the rival
of other men; he delights in competition, and this leads to ambition
which passes too easily into selfishness. These latter qualities seem
to be his natural and unfortunate birthright. It is generally admitted
that with woman the powers of intuition, of rapid perception, and
perhaps of imitation, are more strongly marked than in man; but some,
at least, of these faculties are characteristic of the lower races, and
therefore of a past and lower state of civilization.
The chief distinction in the intellectual powers of the two sexes is
shown by man’s attaining to a higher eminence, in whatever he takes up,
than can woman--whether requiring deep thought, reason, or imagination,
or merely the use of the senses and hands. If two lists were made of
the most eminent men and women in poetry, painting, sculpture, music
(inclusive both of composition and performance), history, science,
and philosophy, with half a dozen names under each subject, the two
lists would not bear comparison. We may also infer, from the law of
the deviation from averages, so well illustrated by Mr. Galton, in
his work on “Hereditary Genius,” that if men are capable of a decided
pre-eminence over women in many subjects, the average of mental power
in man must be above that of woman.
Among the half-human progenitors of man, and among savages, there
have been struggles between the males during many generations for the
possession of the females. But mere bodily strength and size would do
little for victory, unless associated with courage, perseverance, and
determined energy. With social animals, the young males have to pass
through many a contest before they win a female, and the older males
have to retain their females by renewed battles. They have, also, in
the case of mankind, to defend their females, as well as their young,
from enemies of all kinds, and to hunt for their joint subsistence.
But to avoid enemies or to attack them with success, to capture wild
animals, or to fashion weapons, requires the aid of the higher mental
faculties, namely, observation, reason, invention, or imagination.
These various faculties will thus have been continually put to the
test and selected during manhood; they will, moreover, have been
strengthened by use during this same period of life. Consequently,
in accordance with the principle often alluded to, we might expect
that they would at least tend to be transmitted chiefly to the male
offspring at the corresponding period of manhood.
HOW WOMAN COULD BE MADE TO REACH THE STANDARD OF MAN.
[Page 565.]
It must be borne in mind that the tendency in characters acquired by
either sex late in life, to be transmitted to the same sex at the same
age, and of early acquired characters to be transmitted to both sexes,
are rules which, though general, do not always hold. If they always
held good, we might conclude (but I here exceed my proper bounds) that
the inherited effects of the early education of boys and girls would be
transmitted equally to both sexes; so that the present inequality in
mental power between the sexes would not be effaced by a similar course
of early training; nor can it have been caused by their dissimilar
early training. In order that woman should reach the same standard
as man, she ought, when nearly adult, to be trained to energy and
perseverance, and to have her reason and imagination exercised to the
highest point; and then she would probably transmit these qualities
chiefly to her adult daughters. All women, however, could not be thus
raised, unless during many generations those who excelled in the above
robust virtues were married, and produced offspring in larger numbers
than other women. As before remarked of bodily strength, although men
do not now fight for their wives, and this form of selection has passed
away, yet during manhood they generally undergo a severe struggle in
order to maintain themselves and their families; and this will tend to
keep up or even increase their mental powers, and, as a consequence,
the present inequality between the sexes.
“CHARACTERISTIC SELFISHNESS OF MAN.”
[Page 577.]
In most, but not all parts of the world, the men are more ornamented
than the women, and often in a different manner; sometimes, though
rarely, the women are hardly at all ornamented. As the women are made
by savages to perform the greatest share of the work, and as they are
not allowed to eat the best kinds of food, so it accords with the
characteristic selfishness of man that they should not be allowed to
obtain or use the finest ornaments. Lastly, it is a remarkable fact, as
proved by the foregoing quotations, that the same fashions in modifying
the shape of the head, in ornamenting the hair, in painting, tattooing,
in perforating the nose, lips, or ears, in removing or filing the
teeth, etc., now prevail, and have long prevailed, in the most distant
quarters of the world. It is extremely improbable that these practices,
followed by so many distinct nations, should be due to tradition from
any common source. They indicate the close similarity of the mind of
man, to whatever race he may belong, just as do the almost universal
habits of dancing, masquerading, and making rude pictures.
NO UNIVERSAL STANDARD OF BEAUTY AMONG MANKIND.
[Page 584.]
The senses of man and of the lower animals seem to be so constituted
that brilliant colors and certain forms, as well as harmonious and
rhythmical sounds, give pleasure and are called beautiful; but why
this should be so we know not. It is certainly not true that there
is in the mind of man any universal standard of beauty with respect
to the human body. It is, however, possible that certain tastes may
in the course of time become inherited, though there is no evidence
in favor of this belief; and if so each race would possess its own
innate ideal standard of beauty. It has been argued that ugliness
consists in an approach to the structure of the lower animals, and no
doubt this is partly true with the more civilized nations, in which
intellect is highly appreciated; but this explanation will hardly apply
to all forms of ugliness. The men of each race prefer what they are
accustomed to; they can not endure any great change; but they like
variety, and admire each characteristic carried to a moderate extreme.
Men accustomed to a nearly oval face, to straight and regular features,
and to bright colors, admire, as we Europeans know, these points when
strongly developed. On the other hand, men accustomed to a broad face,
with high cheekbones, a depressed nose, and a black skin, admire these
peculiarities when strongly marked. No doubt characters of all kinds
may be too much developed for beauty. Hence a perfect beauty, which
implies many characters modified in a particular manner, will be in
every race a prodigy. As the great anatomist Bichat long ago said, if
every one were cast in the same mold, there would be no such thing as
beauty. If all our women were to become as beautiful as the Venus de’
Medici, we should for a time be charmed; but we should soon wish for
variety; and, as soon as we had obtained variety, we should wish to see
certain characters a little exaggerated beyond the then existing common
standard.
* * * * *
[Page 578.]
It is well known that with many Hottentot women the posterior part of
the body projects in a wonderful manner; they are steatopygous; and Sir
Andrew Smith is certain that this peculiarity is greatly admired by the
men. He once saw a woman who was considered a beauty, and she was so
immensely developed behind, that when seated on level ground she could
not rise, and had to push herself along until she came to a slope. Some
of the women in the various negro tribes have the same peculiarity;
and, according to Burton, the Somal men “are said to choose their wives
by ranging them in a line, and by picking her out who projects farthest
_a tergo_. Nothing can be more hateful to a negro than the opposite
form.”
DEVELOPMENT OF THE BEARD.
[Page 602.]
With respect to the beard in man, if we turn to our best guide, the
Quadrumana, we find beards equally developed in both sexes of many
species, but in some, either confined to the males, or more developed
in them than in the females. From this fact and from the curious
arrangement, as well as the bright colors of the hair about the head
of many monkeys, it is highly probable, as before explained, that
the males first acquired their beards through sexual selection as an
ornament, transmitting them in most cases, equally or nearly so, to
their offspring of both sexes. We know from Eschricht that, with
mankind, the female as well as the male fœtus is furnished with much
hair on the face, especially round the mouth; and this indicates that
we are descended from progenitors of whom both sexes are bearded. It
appears therefore at first sight probable that man has retained his
beard from a very early period, while woman lost her beard at the same
time that her body became almost completely divested of hair. Even
the color of our beards seems to have been inherited from an ape-like
progenitor; for, when there is any difference in tint between the
hair of the head and the beard, the latter is lighter colored in all
monkeys and in man. In those Quadrumana in which the male has a larger
beard than that of the female, it is fully developed only at maturity,
just as with mankind; and it is possible that only the later stages of
development have been retained by man. In opposition to this view of
the retention of the beard from an early period, is the fact of its
great variability in different races, and even within the same race;
for this indicates reversion--long-lost characters being very apt to
vary on reappearance.
DEVELOPMENT OF THE MARRIAGE-TIE.
[Descent of
Man, page 590.]
Although the manner of the development of the marriage-tie is an
obscure subject, as we may infer from the divergent opinions on
several points between the three authors who have studied it most
closely, namely, Mr. Morgan, Mr. McLennan, and Sir J. Lubbock, yet,
from the foregoing and several other lines of evidence, it seems
probable that the habit of marriage, in any strict sense of the word,
has been gradually developed; and that almost promiscuous, or very
loose, intercourse was once extremely common throughout the world.
Nevertheless, from the strength of the feeling of jealousy all through
the animal kingdom, as well as from the analogy of the lower animals,
more particularly of those which come nearest to man, I can not believe
that absolutely promiscuous intercourse prevailed in times past,
shortly before man attained to his present rank in the zoological
scale. Man, as I have attempted to show, is certainly descended from
some ape-like creature. With the existing Quadrumana, as far as their
habits are known, the males of some species are monogamous, but live
during only a part of the year with the females; of this the orang
seems to afford an instance. Several kinds, for example, some of the
Indian and American monkeys, are strictly monogamous, and associate all
the year round with their wives. Others are polygamous, for example,
the gorilla and several American species, and each family lives
separate.
* * * * *
[Page 591.]
Therefore, looking far enough back in the stream of time, and judging
from the social habits of man as he now exists, the most probable view
is that he aboriginally lived in small communities, each with a single
wife, or, if powerful, with several, whom he jealously guarded against
all other men. Or he may not have been a social animal, and yet have
lived with several wives, like the gorilla; for all the natives “agree
that but one adult male is seen in a band; when the young male grows
up, a contest takes place for mastery, and the strongest, by killing
and driving out the others, establishes himself as the head of the
community.” The younger males, being thus expelled and wandering about,
would, when at last successful in finding a partner, prevent too close
interbreeding within the limits of the same family.
Although savages are now extremely licentious, and although communal
marriages may formerly have largely prevailed, yet many tribes practice
some form of marriage, but of a far more lax nature than that of
civilized nations. Polygamy, as just stated, is almost universally
followed by the leading men in every tribe. Nevertheless, there
are tribes, standing almost at the bottom of the scale, which are
strictly monogamous. This is the case with the Veddahs of Ceylon; they
have a saying, according to Sir J. Lubbock, that “death alone can
separate husband and wife.” An intelligent Kandyan chief, of course a
polygamist, “was perfectly scandalized at the utter barbarism of living
with only one wife, and never parting until separated by death.” It
was, he said, “just like the Wanderoo monkeys.” Whether savages who now
enter into some form of marriage, either polygamous or monogamous, have
retained this habit from primeval times, or whether they have returned
to some form of marriage, after passing through a stage of promiscuous
intercourse, I will not pretend to conjecture.
UNNATURAL SELECTION IN MARRIAGE.
[Descent of
Man, page 617.]
Man scans with scrupulous care the character and pedigree of his
horses, cattle, and dogs before he matches them; but, when he comes
to his own marriage, he rarely or never takes any such care. He is
impelled by nearly the same motives as the lower animals, when they
are left to their own free choice, though he is in so far superior to
them that he highly values mental charms and virtues. On the other
hand, he is strongly attracted by mere wealth or rank. Yet he might by
selection do something not only for the bodily constitution and frame
of his offspring, but for their intellectual and moral qualities. Both
sexes ought to refrain from marriage, if they are in any marked degree
inferior in body or mind; but such hopes are Utopian, and will never be
even partially realized until the laws of inheritance are thoroughly
known. Every one does good service who aids toward this end. When the
principles of breeding and inheritance are better understood, we shall
not hear ignorant members of our Legislature rejecting with scorn a
plan for ascertaining whether or not consanguineous marriages are
injurious to man.
The advancement of the welfare of mankind is a most intricate problem:
all ought to refrain from marriage who can not avoid abject poverty
for their children; for poverty is not only a great evil, but tends
to its own increase by leading to recklessness in marriage. On the
other hand, as Mr. Galton has remarked, if the prudent avoid marriage,
while the reckless marry, the inferior members tend to supplant the
better members of society. Man, like every other animal, has no doubt
advanced to his present high condition through a struggle for existence
consequent on his rapid multiplication; and, if he is to advance still
higher, it is to be feared that he must remain subject to a severe
struggle. Otherwise he would sink into indolence, and the more gifted
men would not be more successful in the battle of life than the less
gifted. Hence our natural rate of increase, though leading to many
and obvious evils, must not be greatly diminished by any means. There
should be open competition for all men; and the most able should not
be prevented by laws or customs from succeeding best, and rearing the
largest number of offspring. Important as the struggle for existence
has been, and even still is, yet, as far as the highest part of man’s
nature is concerned, there are other agencies more important. For
the moral qualities are advanced, either directly or indirectly, much
more through the effects of habit, the reasoning powers, instruction,
religion, etc., than through natural selection; though to this latter
agency may be safely attributed the social instincts which afforded the
basis for the development of the moral sense.
MODIFYING INFLUENCES IN BOTH SEXES.
[Page 596.]
With animals in a state of nature, many characters proper to the males,
such as size, strength, special weapons, courage, and pugnacity, have
been acquired through the law of battle. The semi-human progenitors of
man, like their allies the Quadrumana, will almost certainly have been
thus modified; and, as savages still fight for the possession of their
women, a similar process of selection has probably gone on in a greater
or less degree to the present day. Other characters proper to the males
of the lower animals, such as bright colors and various ornaments, have
been acquired by the more attractive males having been preferred by the
females. There are, however, exceptional cases in which the males are
the selectors, instead of having been the selected. We recognize such
cases by the females being more highly ornamented than the males--their
ornamental characters having been transmitted exclusively or chiefly to
their female offspring. One such case has been described in the order
to which man belongs, that of the Rhesus monkey.
Man is more powerful in body and mind than woman, and in the savage
state he keeps her in a far more abject state of bondage than does the
male of any other animal; therefore it is not surprising that he should
have gained the power of selection. Women are everywhere conscious of
the value of their own beauty; and, when they have the means, they take
more delight in decorating themselves with all sorts of ornaments than
do men. They borrow the plumes of male birds, with which nature has
decked this sex in order to charm the females. As women have long been
selected for beauty, it is not surprising that some of their successive
variations should have been transmitted exclusively to the same sex;
consequently that they should have transmitted beauty in a somewhat
higher degree to their female than to their male offspring, and thus
have become more beautiful, according to general opinion, than men.
Women, however, certainly transmit most of their characters, including
some beauty, to their offspring of both sexes; so that the continued
preference by the men of each race for the more attractive women,
according to their standard of taste, will have tended to modify in the
same manner all the individuals of both sexes belonging to the race.
* * * * *
[Page 617.]
He who admits the principle of sexual selection will be led to the
remarkable conclusion that the nervous system not only regulates most
of the existing functions of the body, but has indirectly influenced
the progressive development of various bodily structures and of certain
mental qualities. Courage, pugnacity, perseverance, strength and
size of body, weapons of all kinds, musical organs, both vocal and
instrumental, bright colors and ornamental appendages, have all been
indirectly gained by the one sex or the other, through the exertion of
choice, the influence of love and jealousy, and the appreciation of
the beautiful in sound, color, or form; and these powers of the mind
manifestly depend on the development of the brain.
“GROUNDS THAT WILL NEVER BE SHAKEN.”
[Descent of
Man, page 606.]
Many of the views which have been advanced are highly speculative, and
some no doubt will prove erroneous; but I have in every case given the
reasons which have led me to one view rather than to another. It seemed
worth while to try how far the principle of evolution would throw light
on some of the more complex problems in the natural history of man.
False facts are highly injurious to the progress of science, for they
often endure long; but false views, if supported by some evidence, do
little harm, for every one takes a salutary pleasure in proving their
falseness; and, when this is done, one path toward error is closed and
the road to truth is often at the same time opened.
The main conclusion here arrived at, and now held by many naturalists
who are well competent to form a sound judgment, is that man is
descended from some less highly organized form. The grounds upon which
this conclusion rests will never be shaken, for the close similarity
between man and the lower animals in embryonic development, as well
as in innumerable points of structure and constitution, both of high
and of the most trifling importance--the rudiments which he retains,
and the abnormal reversions to which he is occasionally liable--are
facts which can not be disputed. They have long been known, but until
recently they told us nothing with respect to the origin of man.
Now, when viewed by the light of our knowledge of the whole organic
world, their meaning is unmistakable. The great principle of evolution
stands up clear and firm, when these groups of facts are considered in
connection with others, such as the mutual affinities of the members of
the same group, their geographical distribution in past and present
times, and their geological succession. It is incredible that all these
facts should speak falsely. He who is not content to look, like a
savage, at the phenomena of nature as disconnected, can not any longer
believe that man is the work of a separate act of creation. He will
be forced to admit that the close resemblance of the embryo of man to
that, for instance, of a dog--the construction of his skull, limbs, and
whole frame on the same plan with that of other mammals, independently
of the uses to which the parts may be put--the occasional reappearance
of various structures, for instance of several muscles, which man does
not normally possess, but which are common to the Quadrumana--and a
crowd of analogous facts--all point in the plainest manner to the
conclusion that man is the co-descendant with other mammals of a common
progenitor.
XII.
THE EXPRESSION OF THE EMOTIONS IN MAN AND OTHER ANIMALS.
_The subject is treated under three Principles: the Principle of
Associated Habit; the Principle of Antithesis; and the Principle
of the direct action of the nervous system independent of Will
and Habit._
THE PRINCIPLE OF ASSOCIATED HABIT.
[Expression of
the Emotions,
page 29.]
It is notorious how powerful is the force of habit. The most complex
and difficult movements can in time be performed without the least
effort or consciousness. It is not positively known how it comes
that habit is so efficient in facilitating complex movements; but
physiologists admit that “the conducting power of the nervous fibers
increases with the frequency of their excitement.” This applies to the
nerves of motion and sensation, as well as to those connected with
the act of thinking. That some physical change is produced in the
nerve-cells or nerves which are habitually used can hardly be doubted,
for otherwise it is impossible to understand how the tendency to
certain acquired movements is inherited.
* * * * *
[Page 31.]
It is known to every one how difficult or even impossible it is,
without repeated trials, to move the limbs in certain opposed
directions which have never been practiced. Analogous cases occur with
sensations, as in the common experiment of rolling a marble beneath the
tips of two crossed fingers, when it feels exactly like two marbles.
Every one protects himself when falling to the ground by extending his
arms, and as Professor Alison has remarked, few can resist acting thus
when voluntarily falling on a soft bed. A man when going out-of-doors
puts on his gloves quite unconsciously; and this may seem an extremely
simple operation, but he who has taught a child to put on gloves knows
that this is by no means the case.
When our minds are much affected, so are the movements of our bodies.
* * * * *
[Page 30.]
To those who admit the gradual evolution of species, a most striking
instance of the perfection with which the most difficult consensual
movements can be transmitted, is afforded by the hummingbird
Sphinx-moth (_Macroglossa_); for this moth, shortly after its emergence
from the cocoon, as shown by the bloom on its unruffled scales, may be
seen poised stationary in the air, with its long, hair-like proboscis
uncurled and inserted into the minute orifices of flowers; and no one,
I believe, has ever seen this moth learning to perform its difficult
task, which requires such unerring aim.
* * * * *
[Page 32.]
A vulgar man often scratches his head when perplexed in mind; and I
believe that he acts thus from habit, as if he experienced a slightly
uncomfortable bodily sensation, namely, the itching of his head,
to which he is particularly liable, and which he thus relieves.
Another man rubs his eyes when perplexed, or gives a little cough
when embarrassed, acting in either case as if he felt a slightly
uncomfortable sensation in his eyes or windpipe.
From the continued use of the eyes, these organs are especially
liable to be acted on through association under various states of
the mind, although there is manifestly nothing to be seen. A man, as
Gratiolet remarks, who vehemently rejects a proposition, will almost
certainly shut his eyes or turn away his face; but, if he accepts the
proposition, he will nod his head in affirmation and open his eyes
widely. The man acts in this latter case as if he clearly saw the
thing, and in the former case as if he did not, or would not, see it. I
have noticed that persons in describing a horrid sight often shut their
eyes momentarily and firmly, or shake their heads, as if not to see or
to drive away something disagreeable; and I have caught myself, when
thinking in the dark of a horrid spectacle, closing my eyes firmly.
* * * * *
[Page 34.]
There are other actions which are commonly performed under certain
circumstances, independently of habit, and which seem to be due to
imitation or some sort of sympathy. Thus persons cutting anything with
a pair of scissors may be seen to move their jaws simultaneously with
the blades of the scissors. Children learning to write often twist
about their tongues as their fingers move, in a ridiculous fashion.
When a public singer suddenly becomes a little hoarse, many of those
present may be heard, as I have been assured by a gentleman on whom I
can rely, to clear their throats; but here habit probably comes into
play, as we clear our own throats under similar circumstances.
* * * * *
[Page 35.]
Reflex actions, in the strict sense of the term, are due to the
excitement of a peripheral nerve, which transmits its influence to
certain nerve-cells, and these, in their turn, excite certain muscles
or glands into action; and all this may take place without any
sensation or consciousness on our part, though often thus accompanied.
As many reflex actions are highly expressive, the subject must here
be noticed at some little length. We shall also see that some of them
graduate into, and can hardly be distinguished from, actions which have
arisen through habit. Coughing and sneezing are familiar instances of
reflex actions.
* * * * *
[Page 37.]
The conscious wish to perform a reflex action sometimes stops or
interrupts its performance, though the proper sensory nerves may be
stimulated. For instance, many years ago I laid a small wager with a
dozen young men that they would not sneeze if they took snuff, although
they all declared that they invariably did so; accordingly, they all
took a pinch, but, from wishing much to succeed, not one sneezed,
though their eyes watered, and all, without exception, had to pay me
the wager.
* * * * *
[Page 42.]
Dogs, when they wish to go to sleep on a carpet or other hard surface,
generally turn round and round and scratch the ground with their
fore-paws in a senseless manner, as if they intended to trample down
the grass and scoop out a hollow, as, no doubt, their wild parents did,
when they lived on open, grassy plains or in the woods.
THE PRINCIPLE OF ANTITHESIS.
[Expression of
the Emotions,
page 50.]
Certain states of the mind lead, as we have seen in the last chapter,
to certain habitual movements which were primarily, or may still be,
of service; and we shall find that, when a directly opposite state
of mind is induced, there is a strong and involuntary tendency to the
performance of movements of a directly opposite nature, though these
have never been of any service.
* * * * *
When a dog approaches a strange dog or man in a savage or hostile
frame of mind, he walks upright and very stiffly; his head is slightly
raised, or not much lowered; the tail is held erect and quite rigid;
the hairs bristle, especially along the neck and back; the pricked ears
are directed forward, and the eyes have a fixed stare. These actions
follow from the dog’s intention to attack his enemy, and are thus to a
large extent intelligible. As he prepares to spring with a savage growl
on his enemy, the canine teeth are uncovered, and the ears are pressed
close backward on the head; but with these latter actions we are not
here concerned. Let us now suppose that the dog suddenly discovers
that the man whom he is approaching is not a stranger, but his master;
and let it be observed how completely and instantaneously his whole
bearing is reversed. Instead of walking upright, the body sinks
downward or even crouches, and is thrown into flexuous movements; his
tail, instead of being held stiff and upright, is lowered and wagged
from side to side; his hair instantly becomes smooth; his ears are
depressed and drawn backward, but not closely to the head; and his lips
hang loosely. From the drawing back of the ears, the eyelids become
elongated, and the eyes no longer appear round and staring. It should
be added that the animal is at such times in an excited condition from
joy; and nerve-force will be generated in excess, which naturally
leads to action of some kind. Not one of the above movements, so
clearly expressive of affection, are of the least direct service to the
animal. They are explicable, as far as I can see, solely from being in
complete opposition or antithesis to the attitude and movements which,
from intelligible causes, are assumed when a dog intends to fight, and
which consequently are expressive of anger.
ORIGIN OF THE PRINCIPLE OF ANTITHESIS.
[Page 60.]
We will now consider how the principle of antithesis in expression has
arisen. With social animals, the power of intercommunication between
the members of the same community--and, with other species, between
the opposite sexes, as well as between the young and the old--is of
the highest importance to them. This is generally effected by means of
the voice, but it is certain that gestures and expressions are to a
certain extent mutually intelligible. Man not only uses inarticulate
cries, gestures, and expressions, but has invented articulate language;
if, indeed, the word _invented_ can be applied to a process completed
by innumerable steps, half-consciously made. Any one who has watched
monkeys will not doubt that they perfectly understand each other’s
gestures and expression, and to a large extent, as Rengger asserts,
those of man. An animal when going to attack another, or when afraid
of another, often makes itself appear terrible, by erecting its hair,
thus increasing the apparent bulk of its body, by showing its teeth, or
brandishing its horns, or by uttering fierce sounds.
As the power of intercommunication is certainly of high service to many
animals, there is no _a priori_ improbability in the supposition that
gestures manifestly of an opposite nature to those by which certain
feelings are already expressed should at first have been voluntarily
employed under the influence of an opposite state of feeling. The
fact of the gestures being now innate would be no valid objection to
the belief that they were at first intentional; for, if practiced
during many generations, they would probably at last be inherited.
Nevertheless, it is more than doubtful, as we shall immediately
see, whether any of the cases which come under our present head of
antithesis have thus originated.
With conventional signs which are not innate, such as those used by
the deaf and dumb and by savages, the principle of opposition or
antithesis has been partially brought into play. The Cistercian monks
thought it sinful to speak, and, as they could not avoid holding some
communication, they invented a gesture language, in which the principle
of opposition seems to have been employed. Dr. Scott, of the Exeter
Deaf and Dumb Institution, writes to me that “opposites are greatly
used in teaching the deaf and dumb, who have a lively sense of them.”
Nevertheless I have been surprised how few unequivocal instances can be
adduced. This depends partly on all the signs having commonly had some
natural origin; and partly on the practice of the deaf and dumb and of
savages to contract their signs as much as possible for the sake of
rapidity. Hence their natural source or origin often becomes doubtful,
or is completely lost; as is likewise the case with articulate language.
* * * * *
[Page 64.]
When a cat, or rather when some early progenitor of the species, from
feeling affectionate, first slightly arched its back, held its tail
perpendicularly upward and pricked its ears, can it be believed that
the animal consciously wished thus to show that its frame of mind
was directly the reverse of that when, from being ready to fight or
to spring on its prey, it assumed a crouching attitude, curled its
tail from side to side, and depressed its ears? Even still less can
I believe that my dog voluntarily put on his dejected attitude and
“_hot-house face_,” which formed so complete a contrast to his previous
cheerful attitude and whole bearing. It can not be supposed that he
knew that I should understand his expression, and that he could thus
soften my heart and make me give up visiting the hot-house.
Hence, for the development of the movements which come under the
present head, some other principle, distinct from the will and
consciousness, must have intervened. This principle appears to be that
every movement which we have voluntarily performed throughout our
lives has required the action of certain muscles; and, when we have
performed a directly opposite movement, an opposite set of muscles has
been habitually brought into play--as in turning to the right or to the
left, in pushing away or pulling an object toward us, and in lifting or
lowering a weight.
THE PRINCIPLE OF THE ACTION OF THE EXCITED NERVOUS SYSTEM ON THE BODY.
[Expression of
the Emotions,
page 66.]
The most striking case, though a rare and abnormal one, which can be
adduced of the direct influence of the nervous system, when strongly
affected, on the body, is the loss of color in the hair, which has
occasionally been observed after extreme terror or grief. One authentic
instance has been recorded, in the case of a man brought out for
execution in India, in which the change of color was so rapid that it
was perceptible to the eye.
Another good case is that of the trembling of the muscles, which is
common to man and to many, or most, of the lower animals. Trembling
is of no service, often of much disservice, and can not have been
at first acquired through the will, and then rendered habitual in
association with any emotion. I am assured by an eminent authority
that young children do not tremble, but go into convulsions, under
the circumstances which would induce excessive trembling in adults.
Trembling is excited in different individuals in very different
degrees, and by the most diversified causes--by cold to the surface,
before fever-fits, although the temperature of the body is then above
the normal standard; in blood-poisoning, delirium tremens, and other
diseases; by general failure of power in old age; by exhaustion after
excessive fatigue; locally from severe injuries, such as burns; and, in
an especial manner, by the passage of a catheter. Of all emotions, fear
notoriously is the most apt to induce trembling; but so do occasionally
great anger and joy. I remember once seeing a boy who had just shot
his first snipe on the wing, and his hands trembled to such a degree
from delight that he could not for some time reload his gun; and I have
heard of an exactly similar case with an Australian savage, to whom a
gun had been lent. Fine music, from the vague emotions thus excited,
causes a shiver to run down the backs of some persons.
* * * * *
[Page 69.]
When animals suffer from an agony of pain, they generally writhe about
with frightful contortions; and those which habitually use their
voices utter piercing cries or groans. Almost every muscle of the
body is brought into strong action. With man the mouth may be closely
compressed, or, more commonly, the lips are retracted, with the teeth
clinched or ground together.
* * * * *
[Page 75.]
The heart will be all the more readily affected through habitual
associations, as it is not under the control of the will. A man when
moderately angry, or even when enraged, may command the movements of
his body, but he can not prevent his heart from beating rapidly. His
chest will, perhaps, give a few heaves, and his nostrils just quiver,
for the movements of respiration are only in part voluntary. In like
manner, those muscles of the face which are least obedient to the will
will sometimes alone betray a slight and passing emotion. The glands,
again, are wholly independent of the will, and a man suffering from
grief may command his features, but can not always prevent the tears
from coming into his eyes. A hungry man, if tempting food is placed
before him, may not show his hunger by any outward gesture, but he can
not check the secretion of saliva.
* * * * *
[Page 77.]
With all, or almost all, animals, even with birds, terror causes the
body to tremble. The skin becomes pale, sweat breaks out, and the hair
bristles.
* * * * *
[Page 79.]
A physician once remarked to me, as a proof of the exciting nature
of anger, that a man when excessively jaded will sometimes invent
imaginary offenses, and put himself into a passion, unconsciously, for
the sake of reinvigorating himself; and, since hearing this remark, I
have occasionally recognized its full truth.
* * * * *
[Page 81.]
Exertion stimulates the heart, and this reacts on the brain, and aids
the mind to bear its heavy load.
XIII.
MEANS OF THE EXPRESSION OF THE EMOTIONS.
VOCAL ORGANS.
[Expression of
the Emotions,
page 83.]
With many kinds of animals, man included, the vocal organs are
efficient in the highest degree as a means of expression. We have seen
in the last chapter that, when the sensorium is strongly excited, the
muscles of the body are generally thrown into violent action; and,
as a consequence, loud sounds are uttered, however silent the animal
may generally be, and although the sounds may be of no use. Hares and
rabbits, for instance, never, I believe, use their vocal organs, except
in the extremity of suffering; as, when a wounded hare is killed by
the sportsman, or when a young rabbit is caught by a stoat. Cattle and
horses suffer great pain in silence, but when this is excessive, and
especially when associated with terror, they utter fearful sounds.
* * * * *
[Page 87.]
That animals utter musical notes is familiar to every one, as we may
daily hear in the singing of birds. It is a more remarkable fact
that an ape, one of the Gibbons, produces an exact octave of musical
sounds, ascending and descending the scale by half-tones; so that this
monkey, “alone of brute mammals, may be said to sing.” From this fact,
and from the analogy of other animals, I have been led to infer that
the progenitors of man probably uttered musical tones before they had
acquired the power of articulate speech; and that, consequently, when
the voice is used under any strong emotion, it tends to assume, through
the principle of association, a musical character.
ERECTION OF THE HAIR.
[Page 96.]
The enraged lion erects his mane. The bristling of the hair along
the neck and back of the dog, and over the whole body of the cat,
especially on the tail, is familiar to every one. With the cat it
apparently occurs only under fear; with the dog, under anger and fear;
but not, as far as I have observed, under abject fear, as when a dog is
going to be flogged by a severe gamekeeper. If, however, the dog shows
fight, as sometimes happens, up goes his hair. I have often noticed
that the hair of a dog is particularly liable to rise if he is half
angry and half afraid, as on beholding some object only indistinctly
seen in the dusk.
* * * * *
[Page 97.]
Birds belonging to all the chief orders ruffle their feathers when
angry or frightened. Every one must have seen two cocks, even quite
young birds, preparing to fight with erected neck-hackles; nor
can these feathers when erected serve as a means of defense, for
cock-fighters have found by experience that it is advantageous to trim
them. The male Ruff (_Machetes pugnax_) likewise erects its collar of
feathers when fighting. When a dog approaches a common hen with her
chickens, she spreads out her wings, raises her tail, ruffles all her
feathers, and, looking as ferocious as possible, dashes at the intruder.
* * * * *
[Page 105.]
Several kinds of snakes inflate themselves when irritated. The
puff-adder (_Clotho arietans_) is remarkable in this respect; but, I
believe, after carefully watching these animals, that they do not act
thus for the sake of increasing their apparent bulk, but simply for
inhaling a large supply of air, so as to produce their surprisingly
loud, harsh, and prolonged hissing sound.
ERECTION OF THE EARS.
[Page 111.]
The ears through their movements are highly expressive in many animals;
but in some, such as man, the higher apes, and many ruminants, they
fail in this respect. A slight difference in position serves to express
in the plainest manner a different state of mind, as we may daily see
in the dog; but we are here concerned only with the ears being drawn
closely backward and pressed to the head. A savage frame of mind is
thus shown, but only in the case of those animals which fight with
their teeth; and the care which they take to prevent their ears being
seized by their antagonists accounts for this position. Consequently,
through habit and association, whenever they feel slightly savage, or
pretend in their play to be savage, their ears are drawn back. That
this is the true explanation may be inferred from the relation which
exists in very many animals between their manner of fighting and the
retraction of their ears.
All the Carnivora fight with their canine teeth, and all, as far as I
have observed, draw their ears back when feeling savage.
A STARTLED HORSE.
[Expressions
of the
Emotions,
page 130.]
The actions of a horse when much startled are highly expressive. One
day my horse was much frightened at a drilling-machine, covered by a
tarpaulin, and lying on an open field. He raised his head so high that
his neck became almost perpendicular; and this he did from habit, for
the machine lay on a slope below, and could not have been seen with
more distinctness through the raising of the head; nor, if any sound
had proceeded from it, could the sound have been more distinctly heard.
His eyes and ears were directed intently forward; and I could feel
through the saddle the palpitations of his heart. With red, dilated
nostrils he snorted violently, and, whirling round, would have dashed
off at full speed, had I not prevented him. The distention of the
nostrils is not for the sake of scenting the source of danger, for,
when a horse smells carefully at any object and is not alarmed, he
does not dilate his nostrils. Owing to the presence of a valve in the
throat, a horse when panting does not breathe through his open mouth,
but through his nostrils; and these consequently have become endowed
with great powers of expansion. This expansion of the nostrils, as well
as the snorting, and the palpitations of the heart, are actions which
have become firmly associated during a long series of generations with
the emotion of terror; for terror has habitually led the horse to the
most violent exertion in dashing away at full speed from the cause of
danger.
MONKEY-SHINES.
[Page 142.]
Many years ago, in the Zoölogical Gardens, I placed a looking-glass
on the floor before two young orangs, who, as far as it was known,
had never before seen one. At first they gazed at their own images
with the most steady surprise, and often changed their point of view.
They then approached close and protruded their lips toward the image,
as if to kiss it, in exactly the same manner as they had previously
done toward each other, when first placed, a few days before, in the
same room. They next made all sorts of grimaces, and put themselves
in various attitudes before the mirror; they pressed and rubbed the
surface; they placed their hands at different distances behind it;
looked behind it; and finally seemed almost frightened, started a
little, became cross, and refused to look any longer.
When we try to perform some little action which is difficult and
requires precision, for instance, to thread a needle, we generally
close our lips firmly, for the sake, I presume, of not disturbing our
movements by breathing; and I noticed the same action in a young orang.
The poor little creature was sick, and was amusing itself by trying
to kill the flies on the window-panes with its knuckles; this was
difficult as the flies buzzed about, and at each attempt the lips were
firmly compressed, and at the same time slightly protruded.
WEEPING OF MAN AND BRUTE.
[Expression of
the Emotion,
page 153.]
Infants while young do not shed tears or weep, as is known to nurses
and medical men. This circumstance is not exclusively due to the
lachrymal glands being as yet incapable of secreting tears. I first
noticed this fact from having accidentally brushed with the cuff of
my coat the open eye of one of my infants, when seventy-seven days
old, causing this eye to water freely; and, though the child screamed
violently, the other eye remained dry, or was only slightly suffused
with tears. A similar slight effusion occurred ten days previously
in both eyes during a screaming-fit. The tears did not run over the
eyelids and roll down the cheeks of this child, while screaming
badly, when one hundred and twenty-two days old. This first happened
seventeen days later, at the age of one hundred and thirty-nine days.
A few other children have been observed for me, and the period of free
weeping appears to be very variable. In one case, the eyes became
slightly suffused at the age of only twenty days; in another, at
sixty-two days. With two other children, the tears did _not_ run down
the face at the ages of eighty-four and one hundred and ten days; but
in a third child they did run down at the age of one hundred and four
days. In one instance, as I was positively assured, tears ran down at
the unusually early age of forty-two days. It would appear as if the
lachrymal glands required some practice in the individual before they
are easily excited into action, in somewhat the same manner as various
inherited consensual movements and tastes require some exercise before
they are fixed and perfected. This is all the more likely with a habit
like weeping, which must have been acquired since the period when man
branched off from the common progenitor of the genus _Homo_ and of the
non-weeping anthropomorphous apes.
* * * * *
[Page 135.]
A woman, who sold a monkey to the Zoölogical Society, believed to
have come from Borneo (_Macacus maurus_ or _M. inornatus_ of Gray),
said that it often cried; and Mr. Bartlett, as well as the keeper
Mr. Sutton, have repeatedly seen it, when grieved, or even when much
pitied, weeping so copiously that the tears rolled down its cheeks.
* * * * *
[Page 155.]
A New Zealand chief “cried like a child because the sailors spoiled his
favorite cloak by powdering it with flour.” I saw in Tierra del Fuego
a native who had lately lost a brother, and who alternately cried with
hysterical violence, and laughed heartily at anything which amused him.
With the civilized nations of Europe there is also much difference
in the frequency of weeping. Englishmen rarely cry, except under the
pressure of the acutest grief; whereas, in some parts of the Continent,
the men shed tears much more readily and freely.
The insane notoriously give way to all their emotions with little
or no restraint; and I am informed by Dr. J. Crichton Browne that
nothing is more characteristic of simple melancholia, even in the male
sex, than a tendency to weep on the slightest occasions, or from no
cause. They also weep disproportionately on the occurrence of any real
cause of grief. The length of time during which some patients weep is
astonishing, as well as the amount of tears which they shed.
* * * * *
[Page 167.]
The Indian elephant is known sometimes to weep. Sir E. Tennent, in
describing those which he saw captured and bound in Ceylon, says some
“lay motionless on the ground, with no other indication of suffering
than the tears which suffused their eyes and flowed incessantly.”
Speaking of another elephant he says: “When overpowered and made fast,
his grief was most affecting; his violence sank to utter prostration,
and he lay on the ground, uttering choking cries, with tears trickling
down his cheeks.”
THE GRIEF-MUSCLES.
[Expression of
the Emotions,
page 180.]
With respect to the eyebrows, they may occasionally be seen to
assume an oblique position in persons suffering from deep dejection
or anxiety; for instance, I have observed this movement in a mother
while speaking about her sick son; and it is sometimes excited by
quite trifling or momentary causes of real or pretended distress. The
eyebrows assume this position owing to the contraction of certain
muscles (namely, the orbiculars, corrugators, and pyramidals of the
nose, which together tend to lower and contract the eyebrows) being
partially checked by the more powerful action of the central fasciæ of
the frontal muscle. These latter fasciæ, by their contraction, raise
the inner ends alone of the eyebrows; and, as the corrugators at the
same time draw the eyebrows together, their inner ends become puckered
into a fold or lump. The eyebrows are at the same time somewhat
roughened, owing to the hairs being made to project. Dr. J. Crichton
Browne has also often noticed, in melancholic patients who keep their
eyebrows persistently oblique, “a peculiar acute arching of the upper
eyelid.” The acute arching of the eyelids depends, I believe, on the
inner end alone of the eyebrows being raised; for, when the whole
eyebrow is elevated and arched, the upper eyelid follows in a slight
degree the same movement.
But the most conspicuous result of the opposed contraction of the
above-named muscles is exhibited by the peculiar furrows formed
on the forehead. These muscles, when thus in conjoint yet opposed
action, may be called, for the sake of brevity, the grief-muscles.
When a person elevates his eyebrows by the contraction of the whole
frontal muscle, transverse wrinkles extend across the whole breadth
of the forehead; but, in the present case, the middle fasciæ alone
are contracted; consequently, transverse furrows are formed across
the middle part alone of the forehead. The skin over the exterior
parts of both eyebrows is at the same time drawn downward and smoothed
by the contraction of the outer portions of the orbicular muscles.
The eyebrows are likewise brought together through the simultaneous
contraction of the corrugators; and this latter action generates
vertical furrows, separating the exterior and lowered part of the skin
of the forehead from the central and raised part. The union of these
vertical furrows with the central and transverse furrows produces a
mark on the forehead which has been compared to a horseshoe; but the
furrows more strictly form three sides of a quadrangle. They are often
conspicuous on the foreheads of adult, or nearly adult, persons, when
their eyebrows are made oblique; but with young children, owing to
their skin not easily wrinkling, they are rarely seen, or mere traces
of them can be detected.
VOLUNTARY POWER OVER THE GRIEF-MUSCLES.
[Page 183.]
Few persons, without some practice, can voluntarily act on their
grief-muscles; but, after repeated trials, a considerable number
succeed, while others never can. The degree of obliquity in the
eyebrows, whether assumed voluntarily or unconsciously, differs much
in different persons. With some who apparently have unusually strong
pyramidal muscles, the contraction of the central fasciæ of the frontal
muscle, although it may be energetic, as shown by the quadrangular
furrows on the forehead, does not raise the inner ends of the eyebrows,
but only prevents their being so much lowered as they otherwise would
have been. As far as I have been able to observe, the grief-muscles are
brought into action much more frequently by children and women than by
men. They are rarely acted on, at least with grown-up persons, from
bodily pain, but almost exclusively from mental distress. Two persons,
who, after some practice, succeeded in acting on their grief-muscles,
found by looking at a mirror that, when they made their eyebrows
oblique, they unintentionally at the same time depressed the corners
of their mouths; and this is often the case when the expression is
naturally assumed.
The power to bring the grief-muscles freely into play appears to be
hereditary, like almost every other human faculty. A lady belonging to
a family famous for having produced an extraordinary number of great
actors and actresses, and who can herself give this expression “with
singular precision,” told Dr. Crichton Browne that all her family
had possessed the power in a remarkable degree. The same hereditary
tendency is said to have extended, as I likewise hear from Dr.
Browne, to the last descendant of the family, which gave rise to Sir
Walter Scott’s novel of “Red Gauntlet”; but the hero is described as
contracting his forehead into a horseshoe mark from any strong emotion.
I have also seen a young woman whose forehead seemed almost habitually
thus contracted, independently of any emotion being at the time felt.
The grief-muscles are not very frequently brought into play; and, as
the action is often momentary, it easily escapes observation. Although
the expression, when observed, is universally and instantly recognized
as that of grief or anxiety, yet not one person out of a thousand who
has never studied the subject is able to say precisely what change
passes over the sufferer’s face. Hence probably it is that this
expression is not even alluded to, as far as I have noticed, in any
work of fiction, with the exception of “Red Gauntlet” and of one other
novel; and the authoress of the latter, as I am informed, belongs to
the famous family of actors just alluded to; so that her attention may
have been specially called to the subject.
“DOWN IN THE MOUTH.”
[Page 194.]
To say that a person “is down in the mouth” is synonymous with saying
that he is out of spirits. The depression of the corners may often be
seen, as already stated on the authority of Dr. Crichton Browne and
Mr. Nicol, with the melancholic insane, and was well exhibited in some
photographs, sent to me by the former gentleman, of patients with a
strong tendency to suicide. It has been observed with men belonging to
various races, namely, with Hindoos, the dark hill-tribes of India,
Malays, and, as the Rev. Mr. Hagenauer informs me, with the aborigines
of Australia.
When infants scream they firmly contract the muscles round their eyes,
and this draws up the upper lip; and, as they have to keep their mouths
widely open, the depressor muscles running to the corners are likewise
brought into strong action. This generally, but not invariably, causes
a slight angular bend in the lower lip on both sides, near the corners
of the mouth.
* * * * *
[Page 195.]
It is remarkable how small a depression of the corners of the mouth
gives to the countenance an expression of low spirits or dejection,
so that an extremely slight contraction of these muscles would be
sufficient to betray this state of mind.
I may here mention a trifling observation, as it will serve to sum
up our present subject. An old lady with a comfortable but absorbed
expression sat nearly opposite to me in a railway-carriage. While I was
looking at her I saw that her _depressores anguli oris_ became very
slightly yet decidedly contracted; but, as her countenance remained as
placid as ever, I reflected how meaningless was this contraction, and
how easily one might be deceived. The thought had hardly occurred to
me when I saw that her eyes suddenly became suffused with tears almost
to overflowing, and her whole countenance fell. There could now be
no doubt that some painful recollection, perhaps that of a long-lost
child, was passing through her mind. As soon as her sensorium was thus
affected, certain nerve-cells from long habit instantly transmitted an
order to all the respiratory muscles, and to those round the mouth, to
prepare for a fit of crying. But the order was countermanded by the
will, or rather by a later acquired habit, and all the muscles were
obedient, excepting in a slight degree the _depressores anguli oris_.
The mouth was not even opened; the respiration was not hurried; and no
muscle was affected except those which draw down the corners of the
mouth.
LAUGHTER.
[Expression of
the Emotions,
page 200.]
Many curious discussions have been written on the causes of laughter
with grown-up persons. The subject is extremely complex. Something
incongruous or unaccountable, exciting surprise and some sense of
superiority in the laughter, who must be in a happy frame of mind,
seems to be the commonest cause. The circumstances must not be of a
momentous nature; no poor man would laugh or smile on suddenly hearing
that a large fortune had been bequeathed to him.
* * * * *
[Page 201.]
The imagination is sometimes said to be tickled, by a ludicrous idea;
and this so-called tickling of the mind is curiously analogous with
that of the body. Every one knows how immoderately children laugh
and how their whole bodies are convulsed when they are tickled. The
anthropoid apes, as we have seen, likewise utter a reiterated sound,
corresponding with our laughter, when they are tickled, especially
under the armpits. I touched with a bit of paper the sole of the foot
of one of my infants, when only seven days old, and it was suddenly
jerked away and the toes curled about, as in an older child. Such
movements, as well as laughter from being tickled, are manifestly
reflex actions; and this is likewise shown by the minute unstriped
muscles, which serve to erect the separate hairs on the body,
contracting near a tickled surface. Yet laughter from a ludicrous idea,
though involuntary, can not be called a strictly reflex action. In this
case, and in that of laughter from being tickled, the mind must be in
a pleasurable condition; a young child, if tickled by a strange man,
would scream from fear. The touch must be light, and an idea or event,
to be ludicrous, must not be of grave import. The parts of the body
which are most easily tickled are those which are not commonly touched,
such as the armpits or between the toes, or parts such as the soles
of the feet, which are habitually touched by a broad surface; but the
surface on which we sit offers a marked exception to this rule.
* * * * *
[Page 202.]
The sound of laughter is produced by a deep inspiration followed by
short, interrupted, spasmodic contractions of the chest, and especially
of the diaphragm. Hence we hear of “laughter holding both his sides.”
From the shaking of the body, the head nods to and fro. The lower jaw
often quivers up and down, as is likewise the case with some species of
baboons, when they are much pleased.
During laughter the mouth is opened more or less widely, with the
corners drawn much backward, as well as a little upward; and the upper
lip is somewhat raised. The drawing back of the corners is best seen in
moderate laughter, and especially in a broad smile--the latter epithet
showing how the mouth is widened.
* * * * *
[Page 208.]
Although we can hardly account for the shape of the mouth during
laughter, which leads to wrinkles being formed beneath the eyes, nor
for the peculiar reiterated sound of laughter, nor for the quivering of
the jaws, nevertheless we may infer that all these effects are due to
some common cause; for they are all characteristic and expressive of a
pleased state of mind in various kinds of monkeys.
* * * * *
It is scarcely possible to point out any difference between the
tear-stained face of a person after a paroxysm of excessive laughter
and after a bitter crying-fit. It is probably due to the close
similarity of the spasmodic movements caused by these widely different
emotions that hysteric patients alternately cry and laugh with
violence, and that young children sometimes pass suddenly from the one
to the other state. Mr. Swinhoe informs me that he has often seen the
Chinese, when suffering from deep grief, burst out into hysterical fits
of laughter.
I was anxious to know whether tears are freely shed during excessive
laughter by most of the races of men, and I hear from my correspondents
that this is the case. One instance was observed with the Hindoos, and
they themselves said that it often occurred. So it is with the Chinese.
The women of a wild tribe of Malays in the Malacca Peninsula sometimes
shed tears when they laugh heartily, though this seldom occurs. With
the Dyaks of Borneo it must frequently be the case, at least with
the women, for I hear from the Rajah C. Brooke that it is a common
expression with them to say, “We nearly made tears from laughter.”
* * * * *
[Expression of
the Emotions,
page 133.]
Young orangs, when tickled, grin and make a chuckling sound; and Mr.
Martin says that their eyes grow brighter. As soon as their laughter
ceases, an expression may be detected passing over their faces,
which, as Mr. Wallace remarked to me, may be called a smile. I have
also noticed something of the same kind with the chimpanzee. Dr.
Duchenne--and I can not quote a better authority--informs me that he
kept a very tame monkey in his house for a year; and, when he gave it
during meal-times some choice delicacy, he observed that the corners
of its mouth were slightly raised; thus an expression of satisfaction,
partaking of the nature of an incipient smile, and resembling that
often seen on the face of man, could be plainly perceived in this
animal.
EXPRESSION OF THE DEVOUT EMOTIONS.
[Page 220.]
With some sects, both past and present, religion and love have been
strangely combined; and it has even been maintained, lamentable as
the fact may be, that the holy kiss of love differs but little from
that which a man bestows on a woman, or a woman on a man. Devotion is
chiefly expressed by the face being directed toward the heavens, with
the eyeballs upturned. Sir C. Bell remarks that, at the approach of
sleep, or of a fainting-fit, or of death, the pupils are drawn upward
and inward; and he believes that “when we are rapt in devotional
feelings, and outward impressions are unheeded, the eyes are raised by
an action neither taught nor acquired”; and that this is due to the
same cause as in the above cases. That the eyes are upturned during
sleep is, as I hear from Professor Donders, certain. With babies, while
sucking their mother’s breast, this movement of the eyeballs often
gives to them an absurd appearance of ecstatic delight; and here it may
be clearly perceived that a struggle is going on against the position
naturally assumed during sleep. But Sir C. Bell’s explanation of the
fact, which rests on the assumption that certain muscles are more under
the control of the will than others, is, as I hear from Professor
Donders, incorrect. As the eyes are often turned up in prayer, without
the mind being so much absorbed in thought as to approach to the
unconsciousness of sleep, the movement is probably a conventional
one--the result of the common belief that Heaven, the source of Divine
power to which we pray, is seated above us.
A humble kneeling posture, with the hands upturned and palms joined,
appears to us, from long habit, a gesture so appropriate to devotion,
that it might be thought to be innate; but I have not met with any
evidence to this effect with the various extra-European races of
mankind. During the classical period of Roman history it does not
appear, as I hear from an excellent classic, that the hands were thus
joined during prayer. Mr. Hensleigh Wedgwood has apparently given
the true explanation, though this implies that the attitude is one
of slavish subjection. “When the suppliant kneels and holds up his
hands with the palms joined, he represents a captive who proves the
completeness of his submission by offering up his hands to be bound
by the victor. It is the pictorial representation of the Latin _dare
manus_, to signify submission.” Hence it is not probable that either
the uplifting of the eyes or the joining of the open hands, under the
influence of devotional feelings, is an innate or a truly expressive
action; and this could hardly have been expected, for it is very
doubtful whether feelings such as we should now rank as devotional
affected the hearts of men while they remained during past ages in an
uncivilized condition.
FROWNING.
[Expression of
the Emotions,
page 225.]
We may now inquire how it is that a frown should express the perception
of something difficult or disagreeable, either in thought or action.
In the same way as naturalists find it advisable to trace the
embryological development of an organ in order fully to understand
its structure, so with the movements of expression it is advisable to
follow as nearly as possible the same plan. The earliest and almost
sole expression seen during the first days of infancy, and then
often exhibited, is that displayed during the act of screaming; and
screaming is excited, both at first and for some time afterward, by
every distressing or displeasing sensation and emotion--by hunger,
pain, anger, jealousy, fear, etc. At such times the muscles round the
eyes are strongly contracted; and this, as I believe, explains to a
large extent the act of frowning during the remainder of our lives. I
repeatedly observed my own infants, from under the age of one week to
that of two or three months, and found that, when a screaming-fit came
on gradually, the first sign was the contraction of the corrugators,
which produced a slight frown, quickly followed by the contraction of
the other muscles round the eyes.
* * * * *
[Page 226.]
Screaming or weeping begins to be voluntarily restrained at an early
period of life, whereas frowning is hardly ever restrained at any age.
It is perhaps worth notice that, with children much given to weeping,
anything which perplexes their minds, and which would cause most other
children merely to frown, readily makes them weep. So with certain
classes of the insane, any effort of mind, however slight, which with
an habitual frowner would cause a slight frown, leads to their weeping
in an unrestrained manner. It is not more surprising that the habit of
contracting the brows at the first perception of something distressing,
although gained during infancy, should be retained during the rest of
our lives, than that many other associated habits acquired at an early
age should be permanently retained both by man and the lower animals.
For instance, full-grown cats, when feeling warm and comfortable,
often retain the habit of alternately protruding their fore-feet with
extended toes, which habit they practiced for a definite purpose while
sucking their mothers.
POUTING.
[Page 232.]
With young children sulkiness is shown by pouting, or, as it is
sometimes called, “making a snout.” When the corners of the mouth
are much depressed, the lower lip is a little everted and protruded;
and this is likewise called a pout. But the pouting here referred
to consists of the protrusion of both lips into a tubular form,
sometimes to such an extent as to project as far as the end of the
nose, if this be short. Pouting is generally accompanied by frowning,
and sometimes by the utterance of a booing or whooing noise. This
expression is remarkable, as almost the sole one, as far as I know,
which is exhibited much more plainly during childhood, at least with
Europeans, than during maturity. There is, however, some tendency to
the protrusion of the lips with the adults of all races under the
influence of great rage. Some children pout when they are shy, and they
can then hardly be called sulky.
* * * * *
[Page 234.]
Young orangs and chimpanzees protrude their lips to an extraordinary
degree, when they are discontented, somewhat angry, or sulky; also
when they are surprised, a little frightened, and even when slightly
pleased. Their mouths are protruded apparently for the sake of making
the various noises proper to these several states of mind; and its
shape, as I observed with the chimpanzee, differed slightly when the
cry of pleasure and that of anger were uttered. As soon as these
animals become enraged, the shape of the mouth wholly changes, and the
teeth are exposed. The adult orang when wounded is said to emit “a
singular cry, consisting at first of high notes, which at length deepen
into a low roar. While giving out the high notes he thrusts out his
lips into a funnel shape, but in uttering the low notes he holds his
mouth wide open.” With the gorilla, the lower lip is said to be capable
of great elongation. If, then, our semi-human progenitors protruded
their lips when sulky or a little angered, in the same manner as do
the existing anthropoid apes, it is not an anomalous, though a curious
fact, that our children should exhibit, when similarly affected, a
trace of the same expression, together with some tendency to utter a
noise. For it is not at all unusual for animals to retain, more or less
perfectly, during early youth, and subsequently to lose, characters
which were aboriginally possessed by their adult progenitors, and which
are still retained by distinct species, their near relations.
DECISION AT THE MOUTH.
[Page 236.]
No determined man probably ever had an habitually gaping mouth. Hence,
also, a small and weak lower jaw, which seems to indicate that the
mouth is not habitually and firmly closed, is commonly thought to be
characteristic of feebleness of character. A prolonged effort of any
kind, whether of body or mind, implies previous determination; and if
it can be shown that the mouth is generally closed with firmness before
and during a great and continued exertion of the muscular system, then,
through the principle of association, the mouth would almost certainly
be closed as soon as any determined resolution was taken.
ANGER.
[Expression of
the Emotions,
page 243.]
The lips are sometimes protruded during rage in a manner the meaning
of which I do not understand, unless it depends on our descent from
some ape-like animal. Instances have been observed, not only with
Europeans, but with the Australians and Hindoos. The lips, however,
are much more commonly retracted, the grinning or clinched teeth being
thus exposed. This has been noticed by almost every one who has written
on expression. The appearance is as if the teeth were uncovered, ready
for seizing or tearing an enemy, though there may be no intention
of acting in this manner. Mr. Dyson Lacy has seen this grinning
expression with the Australians, when quarreling, and so has Gaika
with the Caffres of South Africa. Dickens, in speaking of an atrocious
murderer who had just been caught, and was surrounded by a furious mob,
describes “the people as jumping up one behind another, snarling with
their teeth, and making at him like wild beasts.” Every one who has
had much to do with young children must have seen how naturally they
take to biting, when in a passion. It seems as instinctive in them as
in young crocodiles, who snap their little jaws as soon as they emerge
from the egg.
SNEERING.
[Expression of
the Emotions,
page 253.]
The expression here considered, whether that of a playful sneer or
ferocious snarl, is one of the most curious which occurs in man.
It reveals his animal descent; for no one, even if rolling on the
ground in a deadly grapple with an enemy, and attempting to bite him,
would try to use his canine teeth more than his other teeth. We may
readily believe from our affinity to the anthropomorphous apes that
our male semi-human progenitors possessed great canine teeth, and men
are now occasionally born having them of unusually large size, with
interspaces in the opposite jaw for their reception. We may further
suspect, notwithstanding that we have no support from analogy, that our
semi-human progenitors uncovered their canine teeth when prepared for
battle, as we still do when feeling ferocious, or when merely sneering
at or defying some one, without any intention of making a real attack
with our teeth.
DISGUST.
[Expression of
the Emotions,
page 258.]
Extreme disgust is expressed by movements round the mouth identical
with those preparatory to the act of vomiting. The mouth is opened
widely, with the upper lip strongly retracted, which wrinkles the sides
of the nose, and with the lower lip protruded and everted as much as
possible. This latter movement requires the contraction of the muscles
which draw downward the corners of the mouth.
It is remarkable how readily and instantly retching or actual vomiting
is induced in some persons by the mere idea of having partaken of any
unusual food, as of an animal which is not commonly eaten; although
there is nothing in such food to cause the stomach to reject it.
When vomiting results, as a reflex action, from some real cause--as
from too rich food, or tainted meat, or from an emetic--it does not
ensue immediately, but generally after a considerable interval of
time. Therefore, to account for retching or vomiting being so quickly
and easily excited by a mere idea, the suspicion arises that our
progenitors must formerly have had the power (like that possessed
by ruminants and some other animals) of voluntarily rejecting food
which disagreed with them, or which they thought would disagree with
them; and now, though this power has been lost, as far as the will is
concerned, it is called into involuntary action, through the force of a
formerly well-established habit, whenever the mind revolts at the idea
of having partaken of any kind of food, or at anything disgusting. This
suspicion receives support from the fact, of which I am assured by Mr.
Sutton, that the monkeys in the Zoölogical Gardens often vomit while in
perfect health, which looks as if the act were voluntary. We can see
that as man is able to communicate, by language to his children and
others, the knowledge of the kinds of food to be avoided, he would have
little occasion to use the faculty of voluntary rejection; so that this
power would tend to be lost through disuse.
SHRUGGING THE SHOULDERS.
[Expression of
the Emotions,
page 271.]
We may now inquire why men in all parts of the world, when they
feel--whether or not they wish to show this feeling--that they cannot
or will not do something, or will not resist something if done by
another, shrug their shoulders, at the same time often bending in their
elbows, showing the palms of their hands with extended fingers, often
throwing their heads a little on one side, raising their eyebrows,
and opening their mouths. These states of the mind are either simply
passive, or show a determination not to act. None of the above
movements are of the least service. The explanation lies, I can not
doubt, in the principle of unconscious antithesis. This principle here
seems to come into play as clearly as in the case of a dog, who, when
feeling savage, puts himself in the proper attitude for attacking and
for making himself appear terrible to his enemy; but, as soon as he
feels affectionate, throws his whole body into a directly opposite
attitude, though this is of no direct use to him.
* * * * *
Let it be observed how an indignant man who resents and will not
submit to some injury holds his head erect, squares his shoulders, and
expands his chest. He often clinches his fists, and puts one or both
arms in the proper position for attack or defense, with the muscles
of his limbs rigid. He frowns--that is, he contracts and lowers his
brows--and, being determined, closes his mouth. The actions and
attitude of a helpless man are, in every one of these respects, exactly
the reverse.
BLUSHING.
[Expression of
the Emotions,
page 310.]
Blushing is the most peculiar and the most human of all expressions.
Monkeys redden from passion, but it would require an overwhelming
amount of evidence to make us believe that any animal could blush. The
reddening of the face from a blush is due to the relaxation of the
muscular coats of the small arteries, by which the capillaries become
filled with blood; and this depends on the proper vaso-motor center
being affected. No doubt, if there be at the same time much mental
agitation, the general circulation will be affected; but it is not due
to the action of the heart that the net-work of minute vessels covering
the face becomes, under a sense of shame, gorged with blood. We can
cause laughing by tickling the skin; weeping or frowning, by a blow;
trembling, from a fear of pain, and so forth; but we can not cause a
blush, as Dr. Burgess remarks, by any physical means--that is, by any
action on the body. It is the mind which must be affected. Blushing
is not only involuntary, but the wish to restrain it, by leading to
self-attention, actually increases the tendency.
* * * * *
[Page 312.]
The tendency to blush is inherited. Dr. Burgess gives the case of a
family, consisting of a father, mother, and ten children, all of whom,
without exception, were prone to blush to a most painful degree. The
children were grown up; “and some of them were sent to travel, in
order to wear away this diseased sensibility, but nothing was of the
slightest avail.” Even peculiarities in blushing seem to be inherited.
Sir James Paget, while examining the spine of a girl, was struck at
her singular manner of blushing: a big splash of red appeared first
on one cheek, and then other splashes variously scattered over the
face and neck. He subsequently asked the mother whether her daughter
always blushed in this peculiar manner, and was answered, “Yes, she
takes after me.” Sir J. Paget then perceived that, by asking this
question, he had caused the mother to blush; and she exhibited the same
peculiarity as her daughter.
* * * * *
[Page 318.]
Mr. Washington Matthews has often seen a blush on the faces of the
young squaws belonging to various wild Indian tribes of North America.
At the opposite extremity of the continent, in Tierra del Fuego,
the natives, according to Mr. Bridges, “blush much, but chiefly in
regard to women; but they certainly blush also at their own personal
appearance.” This latter statement agrees with what I remember of the
Fuegian, Jemmy Button, who blushed when he was quizzed about the care
which he took in polishing his shoes, and in otherwise adorning himself.
* * * * *
[Page 319.]
Several trustworthy observers have assured me that they have seen
on the faces of negroes an appearance resembling a blush, under
circumstances which would have excited one in us, though their skins
were of an ebony-black tint. Some describe it as blushing brown, but
most say that the blackness becomes more intense.
* * * * *
[Page 324.]
I will give an instance of the extreme disturbance of mind to which
some sensitive men are liable. A gentleman, on whom I can rely,
assured me that he had been an eye-witness of the following scene: A
small dinner-party was given in honor of an extremely shy man, who,
when he rose to return thanks, rehearsed the speech, which he had
evidently learned by heart, in absolute silence, and did not utter a
single word; but he acted as if he were speaking with much emphasis.
His friends, perceiving how the case stood, loudly applauded the
imaginary bursts of eloquence, whenever his gestures indicated a pause,
and the man never discovered that he had remained the whole time
completely silent. On the contrary, he afterward remarked to my friend,
with much satisfaction, that he thought he had succeeded uncommonly
well.
BLUSHING NOT NECESSARILY AN EXPRESSION OF GUILT.
[Page 333.]
It is not the sense of guilt, but the thought that others think or know
us to be guilty, which crimsons the face. A man may feel thoroughly
ashamed at having told a small falsehood, without blushing; but if he
even suspects that he is detected he will instantly blush, especially
if detected by one whom he reveres.
On the other hand, a man may be convinced that God witnesses all his
actions, and he may feel deeply conscious of some fault and pray for
forgiveness; but this will not, as a lady who is a great blusher
believes, ever excite a blush. The explanation of this difference
between the knowledge by God and man of our actions lies, I presume,
in man’s disapprobation of immoral conduct being somewhat akin in
nature to his depreciation of our personal appearance, so that through
association both lead to similar results; whereas the disapprobation of
God brings up no such association.
Many a person has blushed intensely when accused of some crime, though
completely innocent of it.
* * * * *
[Page 334.]
An action may be meritorious or of an indifferent nature, but a
sensitive person, if he suspects that others take a different view of
it, will blush. For instance, a lady by herself may give money to a
beggar without a trace of a blush, but if others are present, and she
doubts whether they approve, or suspects that they think her influenced
by display, she will blush. So it will be, if she offers to relieve the
distress of a decayed gentlewoman, more particularly of one whom she
had previously known under better circumstances, as she can not then
feel sure how her conduct will be viewed. But such cases as these blend
into shyness.
* * * * *
[Page 338.]
The belief that blushing was _specially_ designed by the Creator is
opposed to the general theory of evolution, which is now so largely
accepted; but it forms no part of my duty here to argue on the general
question. Those who believe in design will find it difficult to
account for shyness being the most frequent and efficient of all the
causes of blushing, as it makes the blusher to suffer and the beholder
uncomfortable, without being of the least service to either of them.
They will also find it difficult to account for negroes and other
dark-colored races blushing, in whom a change of color in the skin is
scarcely or not at all visible.
BLUSHING ACCOUNTED FOR.
The hypothesis which appears to me the most probable, though it may at
first seem rash, is that attention closely directed to any part of the
body tends to interfere with the ordinary and tonic contraction of the
small arteries of that part. These vessels, in consequence, become at
such times more or less relaxed, and are instantly filled with arterial
blood. This tendency will have been much strengthened, if frequent
attention has been paid during many generations to the same part, owing
to nerve-force readily flowing along accustomed channels, and by the
power of inheritance. Whenever we believe that others are depreciating
or even considering our personal appearance, our attention is vividly
directed to the outer and visible parts of our bodies; and of all such
parts we are most sensitive about our faces, as no doubt has been the
case during many past generations. Therefore, assuming for the moment
that the capillary vessels can be acted on by close attention, those
of the face will have become eminently susceptible. Through the force
of association, the same effects will tend to follow whenever we think
that others are considering or censuring our actions or character.
* * * * *
[Page 340.]
It is known that the involuntary movements of the heart are affected if
close attention be paid to them. Gratiolet gives the case of a man who,
by continually watching and counting his own pulse, at last caused one
beat out of every six to intermit. On the other hand, my father told me
of a careful observer, who certainly had heart-disease and died from
it, and who positively stated that his pulse was habitually irregular
to an extreme degree; yet to his great disappointment it invariably
became regular as soon as my father entered the room.
* * * * *
[Page 342.]
When we direct our whole attention to any one sense, its acuteness is
increased; and the continued habit of close attention, as with blind
people to that of hearing, and with the blind and deaf to that of
touch, appears to improve the sense in question permanently. There is,
also, some reason to believe, judging from the capacities of different
races of man, that the effects are inherited. Turning to ordinary
sensations, it is well known that pain is increased by attending to it;
and Sir B. Brodie goes so far as to believe that pain may be felt in
any part of the body to which attention is closely drawn.
A NEW ARGUMENT FOR A SINGLE PARENT-STOCK.
[Expression of
the Emotions,
page 361.]
I have endeavored to show in considerable detail that all the chief
expressions exhibited by man are the same throughout the world. This
fact is interesting, as it affords a new argument in favor of the
several races being descended from a single parent-stock, which must
have been almost completely human in structure, and to a large extent
in mind, before the period at which the races diverged from each other.
No doubt similar structures adapted for the same purpose have often
been independently acquired through variation and natural selection
by distinct species; but this view will not explain close similarity
between distinct species in a multitude of unimportant details. Now, if
we bear in mind the numerous points of structure having no relation to
expression, in which all the races of man closely agree, and then add
to them the numerous points, some of the highest importance and many of
the most trifling value, on which the movements of expression directly
or indirectly depend, it seems to me improbable in the highest degree
that so much similarity, or rather identity of structure, could have
been acquired by independent means. Yet this must have been the case
if the races of man are descended from several aboriginally distinct
species. It is far more probable that the many points of close
similarity in the various races are due to inheritance from a single
parent-form, which had already assumed a human character.
XIV.
THE PROVISIONAL HYPOTHESIS OF PANGENESIS.
[Animals and
Plants under
Domestication,
vol. ii,
page 349.]
Every one would wish to explain to himself, even in an imperfect
manner, how it is possible for a character possessed by some remote
ancestor suddenly to reappear in the offspring; how the effects of
increased or decreased use of a limb can be transmitted to the child;
how the male sexual element can act not solely on the ovules, but
occasionally on the mother-form; how a hybrid can be produced by the
union of the cellular tissue of two plants independently of the organs
of generation; how a limb can be reproduced on the exact line of
amputation, with neither too much nor too little added; how the same
organism may be produced by such widely different processes as budding
and true seminal generation; and, lastly, how, of two allied forms,
one passes in the course of its development through the most complex
metamorphoses, and the other does not do so, though when mature both
are alike in every detail of structure. I am aware that my view is
merely a provisional hypothesis or speculation; but, until a better one
be advanced, it will serve to bring together a multitude of facts which
are at present left disconnected by any efficient cause. As Whewell,
the historian of the inductive sciences, remarks, “Hypotheses may
often be of service to science when they involve a certain portion of
incompleteness, and even of error.” Under this point of view I venture
to advance the hypothesis of pangenesis, which implies that every
separate part of the whole organization reproduces itself. So that
ovules, spermatozoa, and pollen-grains--the fertilized egg or seed, as
well as buds--include and consist of a multitude of germs thrown off
from each separate part or unit.
FUNCTIONAL INDEPENDENCE OF THE UNITS OF THE BODY.
[Page 364.]
Physiologists agree that the whole organism consists of a multitude
of elemental parts, which are to a great extent independent of one
another. Each organ, says Claude Bernard, has its proper life, its
autonomy; it can develop and reproduce itself independently of the
adjoining tissues. A great German authority, Virchow, asserts still
more emphatically that each system consists of an “enormous mass
of minute centers of action.... Every element has its own special
action, and, even though it derive its stimulus to activity from other
parts, yet alone effects the actual performance of duties.... Every
single epithelial and muscular fiber-cell leads a sort of parasitical
existence in relation to the rest of the body.... Every single
bone-corpuscle really possesses conditions of nutrition peculiar to
itself.” Each element, as Sir J. Paget remarks, lives its appointed
time and then dies, and is replaced after being cast off or absorbed.
I presume that no physiologist doubts that, for instance, each
bone-corpuscle of the finger differs from the corresponding corpuscle
in the corresponding joint of the toe; and there can hardly be a doubt
that even those on the corresponding sides of the body differ, though
almost identical in nature. This near approach to identity is curiously
shown in many diseases in which the same exact points on the right and
left sides of the body are similarly affected; thus Sir J. Paget gives
a drawing of a diseased pelvis, in which the bone has grown into a most
complicated pattern, but “there is not one spot or line on one side
which is not represented, as exactly as it would be in a mirror, on the
other.”
Many facts support this view of the independent life of each minute
element of the body. Virchow insists that a single bone-corpuscle or
a single cell in the skin may become diseased. The spur of a cock,
after being inserted into the ear of an ox, lived for eight years,
and acquired a weight of three hundred and ninety-six grammes (nearly
fourteen ounces) and the astonishing length of twenty-four centimetres,
or about nine inches; so that the head of the ox appeared to bear three
horns. The tail of a pig has been grafted into the middle of its back,
and reacquired sensibility. Dr. Ollier inserted a piece of periosteum
from the bone of a young dog under the skin of a rabbit, and true bone
was developed. A multitude of similar facts could be given.
* * * * *
[Page 368.]
What can be more wonderful than that characters, which have disappeared
during scores, or hundreds, or even thousands of generations, should
suddenly reappear perfectly developed, as in the case of pigeons and
fowls, both when purely bred and especially when crossed; or as with
the zebrine stripes on dun-colored horses, and other such cases? Many
monstrosities come under this same head, as when rudimentary organs
are redeveloped, or when an organ which we must believe was possessed
by an early progenitor of the species, but of which not even a
rudiment is left, suddenly reappears, as with the fifth stamen in some
_Scrophulariaceæ_.
* * * * *
[Page 369.]
In every living creature we may feel assured that a host of long-lost
characters lie ready to be evolved under proper conditions. How can
we make intelligible, and connect with other facts, this wonderful
and common capacity of reversion--this power of calling back to life
long-lost characters?
* * * * *
[Page 336.]
Imperfect nails sometimes appear on the stumps of the amputated
fingers of man; and it is an interesting fact that with the snake-like
saurians, which present a series with more and more imperfect limbs,
the terminations of the phalanges first disappear, “the nails becoming
transferred to their proximal remnants, or even to parts which are not
phalanges.”
* * * * *
[Page 387.]
Mr. Salter and Dr. Maxwell Masters have found pollen within the ovules
of the passion-flower and of the rose. Buds may be developed in the
most unnatural positions, as on the petal of a flower. Numerous
analogous facts could be given.
I do not know how physiologists look at such facts as the foregoing.
According to the doctrine of pangenesis, the gemmules of the transposed
organs become developed in the wrong place, from uniting with wrong
cells or aggregates of cells during their nascent state; and this would
follow from a slight modification in their elective affinities.
* * * * *
[Page 388.]
On any ordinary view it is unintelligible how changed conditions,
whether acting on the embryo, the young or the adult, can cause
inherited modifications. It is equally or even more unintelligible, on
any ordinary view, how the effects of the long-continued use or disuse
of a part, or of changed habits of body or mind, can be inherited. A
more perplexing problem can hardly be proposed; but on our view we
have only to suppose that certain cells become at last structurally
modified, and that these throw off similarly modified gemmules. This
may occur at any period of development, and the modification will
be inherited at a corresponding period; for the modified gemmules
will unite in all ordinary cases with the proper preceding cells,
and will consequently be developed at the same period at which the
modification first arose. With respect to mental habits or instincts,
we are so profoundly ignorant of the relation between the brain and
the power of thought that we do not know positively whether a fixed
habit induces any change in the nervous system, though this seems
highly probable; but, when such habit or other mental attribute, or
insanity, is inherited, we must believe that some actual modification
is transmitted; and this implies, according to our hypothesis, that
gemmules derived from modified nerve-cells are transmitted to the
offspring.
NECESSARY ASSUMPTIONS.
[Page 369.]
I have now enumerated the chief facts which every one would desire
to see connected by some intelligible bond. This can be done, if we
make the following assumptions, and much may be advanced in favor of
the chief one. The secondary assumptions can likewise be supported
by various physiological considerations. It is universally admitted
that the cells or units of the body increase by self-division or
proliferation, retaining the same nature, and that they ultimately
become converted into the various tissues and substances of the body.
But besides this means of increase I assume that the units throw off
minute granules which are dispersed throughout the whole system; that
these, when supplied with proper nutriment, multiply by self-division,
and are ultimately developed into units like those from which they
were originally derived. These granules may be called gemmules. They
are collected from all parts of the system to constitute the sexual
elements, and their development in the next generation forms a new
being; but they are likewise capable of transmission in a dormant state
to future generations and may then be developed. Their development
depends on their union with other partially developed, or nascent cells
which precede them in the regular course of growth. Why I use the term
union will be seen when we discuss the direct action of pollen on the
tissues of the mother-plant. Gemmules are supposed to be thrown off by
every unit, not only during the adult state, but during each stage of
development of every organism; but not necessarily during the continued
existence of the same unit. Lastly, I assume that the gemmules in their
dormant state have a mutual affinity for each other, leading to their
aggregation into buds or into the sexual elements. Hence, it is not the
reproductive organs or buds which generate new organisms, but the units
of which each individual is composed. These assumptions constitute the
provisional hypothesis which I have called pangenesis.
* * * * *
[Page 372.]
But I have further to assume that the gemmules in their undeveloped
state are capable of largely multiplying themselves by self-division,
like independent organisms. Delpino insists that to “admit of
multiplication by fissiparity in corpuscles, analogous to seeds
or buds ... is repugnant to all analogy.” But this seems a strange
objection, as Thuret has seen the zoöspore of an alga divide itself,
and each half germinated. Haeckel divided the segmented ovum of a
siphonophora into many pieces, and these were developed. Nor does the
extreme minuteness of the gemmules, which can hardly differ much in
nature from the lowest and simplest organisms, render it improbable
that they should grow and multiply. A great authority, Dr. Beale, says
that “minute yeast-cells are capable of throwing off buds or gemmules,
much less than the 1/100000 of an inch in diameter”; and these he thinks
are “capable of subdivision practically _ad infinitum_.”
A particle of small-pox matter, so minute as to be borne by the wind,
must multiply itself many thousandfold in a person thus inoculated;
and so with the contagious matter of scarlet fever. It has recently
been ascertained that a minute portion of the mucous discharge from an
animal affected with rinderpest, if placed in the blood of a healthy
ox, increases so fast that in a short space of time “the whole mass of
blood, weighing many pounds, is infected, and every small particle of
that blood contains enough poison to give, within less than forty-eight
hours, the disease to another animal.”
* * * * *
[Page 374.]
The gemmules derived from each part or organ must be thoroughly
dispersed throughout the whole system. We know, for instance, that
even a minute fragment of a leaf of a begonia will reproduce the whole
plant; and that if a fresh-water worm is chopped into small pieces,
each will reproduce the whole animal. Considering also the minuteness
of the gemmules and the permeability of all organic tissues, the
thorough dispersion of the gemmules is not surprising. That matter
may be readily transferred without the aid of vessels from part to
part of the body, we have a good instance in a case recorded by Sir J.
Paget of a lady, whose hair lost its color at each successive attack
of neuralgia and recovered it again in the course of a few days. With
plants, however, and probably with compound animals, such as corals,
the gemmules do not ordinarily spread from bud to bud, but are confined
to the parts developed from each separate bud; and of this fact no
explanation can be given.
TWO OBJECTIONS ANSWERED.
[Page 380.]
But we have here to encounter two objections which apply not only to
the regrowth of a part, or of a bisected individual, but to fissiparous
generation and budding. The first objection is that the part which is
reproduced is in the same stage of development as that of the being
which has been operated on or bisected; and in the case of buds,
that the new beings thus produced are in the same stage as that of
the budding parent. Thus a mature salamander, of which the tail has
been cut off, does not reproduce a larval tail; and a crab does not
reproduce a larval leg. In the case of budding it was shown in the
first part of this chapter that the new being thus produced does not
retrograde in development--that is, does not pass through those earlier
stages which the fertilized germ has to pass through. Nevertheless, the
organisms operated on or multiplying themselves by buds must, by our
hypothesis, include innumerable gemmules derived from every part or
unit of the earlier stages of development; and why do not such gemmules
reproduce the amputated part or the whole body at a corresponding early
stage of development?
The second objection, which has been insisted on by Delpino, is that
the tissues, for instance, of a mature salamander or crab, of which
a limb has been removed, are already differentiated and have passed
through their whole course of development; and how can such tissues in
accordance with our hypothesis attract and combine with the gemmules of
the part which is to be reproduced? In answer to these two objections
we must bear in mind the evidence which has been advanced, showing
that at least in a large number of cases the power of regrowth is a
localized faculty, acquired for the sake of repairing special injuries
to which each particular creature is liable; and, in the case of buds
or fissiparous generation, for the sake of quickly multiplying the
organism at a period of life when it can be supported in large numbers.
These considerations lead us to believe that in all such cases a stock
of nascent cells or of partially developed gemmules are retained for
this special purpose either locally or throughout the body, ready to
combine with the gemmules derived from the cells which come next in due
succession. If this be admitted, we have a sufficient answer to the
above two objections. Anyhow, pangenesis seems to throw a considerable
amount of light on the wonderful power of regrowth.
EFFECT OF MORBID ACTION.
[Page 392.]
We have as yet spoken only of the removal of parts, when not followed
by morbid action: but, when the operation is thus followed, it is
certain that the deficiency is sometimes inherited. In a former chapter
instances were given, as of a cow, the loss of whose horn was followed
by suppuration, and her calves were destitute of a horn on the same
side of their heads. But the evidence which admits of no doubt is
that given by Brown-Séquard with respect to Guinea-pigs, which, after
their sciatic nerves had been divided, gnawed off their own gangrenous
toes, and the toes of their offspring were deficient in at least
thirteen instances on the corresponding feet. The inheritance of the
lost part in several of these cases is all the more remarkable as only
one parent was affected; but we know that a congenital deficiency is
often transmitted from one parent alone--for instance, the offspring
of hornless cattle of either sex, when crossed with perfect animals,
are often hornless. How, then, in accordance with our hypothesis can
we account for mutilations being sometimes strongly inherited, if they
are followed by diseased action? The answer probably is that all the
gemmules of the mutilated or amputated part are gradually attracted
to the diseased surface during the reparative process, and are there
destroyed by the morbid action.
TRANSMISSION LIMITED.
[Page 396.]
The transmission of dormant gemmules during many successive generations
is hardly in itself more improbable, as previously remarked, than the
retention during many ages of rudimentary organs, or even only of
a tendency to the production of a rudiment; but there is no reason
to suppose that dormant gemmules can be transmitted and propagated
forever. Excessively minute and numerous as they are believed to be,
an infinite number, derived, during a long course of modification and
descent, from each unit of each progenitor, could not be supported or
nourished by the organism. But it does not seem improbable that certain
gemmules, under favorable conditions, should be retained and go on
multiplying for a much longer period than others. Finally, on the view
here given, we certainly gain some insight into the wonderful fact that
the child may depart from the type of both its parents, and resemble
its grandparents, or ancestors removed by many hundreds of generations.
* * * * *
[Page 398.]
The child, strictly speaking, does not grow into the man, but includes
germs which slowly and successively become developed and form the man.
In the child, as well as in the adult, each part generates the same
part. Inheritance must be looked at as merely a form of growth, like
the self-division of a lowly-organized unicellular organism. Reversion
depends on the transmission from the forefather to his descendants of
dormant gemmules, which occasionally become developed under certain
known or unknown conditions. Each animal and plant may be compared with
a bed of soil full of seeds, some of which soon germinate, some lie
dormant for a period, while others perish. When we hear it said that
a man carries in his constitution the seeds of an inherited disease,
there is much truth in the expression. No other attempt, as far as I
am aware, has been made, imperfect as this confessedly is, to connect
under one point of view these several grand classes of facts. An
organic being is a microcosm--a little universe, formed of a host of
self-propagating organisms, inconceivably minute and numerous as the
stars in heaven.
XV.
OBJECTIONS TO THE THEORY OF DESCENT WITH MODIFICATION CONSIDERED.
[Origin of
Species,
page 63.]
Several writers have misapprehended or objected to the term Natural
Selection. Some have even imagined that natural selection induces
variability, whereas it implies only the preservation of such
variations as arise and are beneficial to the being under its
conditions of life. No one objects to agriculturists speaking of the
potent effects of man’s selection; and in this case the individual
difference given by nature, which man for some object selects, must of
necessity first occur. Others have objected that the term selection
implies conscious choice in the animals which become modified; and it
has even been urged that, as plants have no volition, natural selection
is not applicable to them! In the literal sense of the word, no doubt,
natural selection is a false term; but who ever objected to chemists
speaking of the elective affinities of the various elements?--and yet
an acid can not strictly be said to elect the base with which it in
preference combines. It has been said that I speak of natural selection
as an active power or Deity; but who objects to an author speaking
of the attraction of gravity as ruling the movements of the planets?
Every one knows what is meant and is implied by such metaphorical
expressions; and they are almost necessary for brevity. So again it is
difficult to avoid personifying the word Nature; but I mean by Nature,
only the aggregate action and product of many natural laws, and by laws
the sequence of events as ascertained by us. With a little familiarity
such superficial objections will be forgotten.
MISREPRESENTATIONS CORRECTED.
[Origin of
Species,
page 421.]
As my conclusions have lately been much misrepresented, and it has
been stated that I attribute the modification of species exclusively
to natural selection, I may be permitted to remark that in the first
edition of this work, and subsequently, I placed in a most conspicuous
position--namely, at the close of the introduction--the following
words: “I am convinced that natural selection has been the main but not
the exclusive means of modification.” This has been of no avail. Great
is the power of steady misrepresentation; but the history of science
shows that fortunately this power does not long endure.
It can hardly be supposed that a false theory would explain, in so
satisfactory a manner as does the theory of natural selection, the
several large classes of facts above specified. It has recently been
objected that this is an unsafe method of arguing; but it is a method
used in judging of the common events of life, and has often been used
by the greatest natural philosophers. The undulatory theory of light
has thus been arrived at; and the belief in the revolution of the
earth on its own axis was until lately supported by hardly any direct
evidence. It is no valid objection that science as yet throws no
light on the far higher problem of the essence or origin of life. Who
can explain what is the essence of the attraction of gravity? No one
now objects to following out the results consequent on this unknown
element of attraction; notwithstanding that Leibnitz formerly accused
Newton of introducing “occult qualities and miracles into philosophy.”
I see no good reason why the views given in this volume should shock
the religious feelings of any one. It is satisfactory, as showing how
transient such impressions are, to remember that the greatest discovery
ever made by man, namely, the law of the attraction of gravity, was
also attacked by Leibnitz, “as subversive of natural, and inferentially
of revealed, religion.” A celebrated author and divine has written to
me that “he has gradually learned to see that it is just as noble a
conception of the Deity to believe that he created a few original forms
capable of self-development into other and needful forms, as to believe
that he required a fresh act of creation to supply the voids caused by
the action of his laws.”
LAPSE OF TIME AND EXTENT OF AREA.
[Origin of
Species,
page 82.]
The mere lapse of time by itself does nothing, either for or against
natural selection. I state this because it has been erroneously
asserted that the element of time has been assumed by me to play an
all-important part in modifying species, as if all the forms of life
were necessarily undergoing change through some innate law. Lapse of
time is only so far important, and its importance in this respect is
great, that it gives a better chance of beneficial variations arising,
and of their being selected, accumulated, and fixed. It likewise tends
to increase the direct action of the physical conditions of life, in
relation to the constitution of each organism.
If we turn to nature to test the truth of these remarks, and look
at any small isolated area, such as an oceanic island, although the
number of species inhabiting it is small, as we shall see in our
chapter on “Geographical Distribution,” yet of these species a very
large proportion are endemic--that is, have been produced there, and
nowhere else in the world. Hence an oceanic island at first sight
seems to have been highly favorable for the production of new species.
But we may thus deceive ourselves, for, to ascertain whether a small
isolated area, or a large open area like a continent, has been most
favorable for the production of new organic forms, we ought to make the
comparison within equal times; and this we are incapable of doing.
Although isolation is of great importance in the production of new
species, on the whole I am inclined to believe that largeness of area
is still more important, especially for the production of species which
shall prove capable of enduring for a long period, and of spreading
widely. Throughout a great and open area, not only will there be a
better chance of favorable variations, arising from the large number
of individuals of the same species there supported, but the conditions
of life are much more complex from the large number of already
existing species; and if some of these many species become modified
and improved, others will have to be improved in a corresponding
degree, or they will be exterminated. Each new form, also, as soon as
it has been much improved, will be able to spread over the open and
continuous area, and will thus come into competition with many other
forms. Moreover, great areas, though now continuous, will often, owing
to former oscillations of level, have existed in a broken condition; so
that the good effects of isolation will generally, to a certain extent,
have concurred. Finally, I conclude that, although small isolated
areas have been in some respects highly favorable for the production of
new species, yet that the course of modification will generally have
been more rapid on large areas; and what is more important, that the
new forms produced on large areas, which already have been victorious
over many competitors, will be those that will spread most widely, and
will give rise to the greatest number of new varieties and species.
They will thus play a more important part in the changing history of
the organic world.
WHY THE HIGHER FORMS HAVE NOT SUPPLANTED THE LOWER.
[Origin of
Species,
page 98.]
But it may be objected that if all organic beings thus tend to rise
in the scale, how is it that throughout the world a multitude of the
lowest forms still exist; and how is it that in each great class some
forms are far more highly developed than others? Why have not the
more highly developed forms everywhere supplanted and exterminated
the lower? Lamarck, who believed in an innate and inevitable tendency
toward perfection in all organic beings, seems to have felt this
difficulty so strongly that he was led to suppose that new and simple
forms are continually being produced by spontaneous generation. Science
has not as yet proved the truth of this belief, whatever the future
may reveal. On our theory the continued existence of lowly organisms
offers no difficulty; for natural selection, or the survival of the
fittest, does not necessarily include progressive development--it only
takes advantage of such variations as arise and are beneficial to each
creature under its complex relations of life. And it may be asked,
What advantage, as far as we can see, would it be to an infusorian
animalcule--to an intestinal worm--or even to an earth-worm, to be
highly organized? If it were no advantage, these forms would be left,
by natural selection, unimproved or but little improved, and might
remain for indefinite ages in their present lowly condition. And
geology tells us that some of the lowest forms, as the infusoria and
rhizopods, have remained for an enormous period in nearly their present
state. But to suppose that most of the many now existing low forms
have not in the least advanced since the first dawn of life would be
extremely rash; for every naturalist who has dissected some of the
beings now ranked as very low in the scale must have been struck with
their really wondrous and beautiful organization.
Nearly the same remarks are applicable if we look to the different
grades of organization within the same great group; for instance,
in the vertebrata, to the co-existence of mammals and fish--among
mammalia, to the co-existence of man and the ornithorhynchus--among
fishes, to the co-existence of the shark and the lancelet (Amphioxus),
which latter fish in the extreme simplicity of its structure approaches
the invertebrate classes. But mammals and fish hardly come into
competition with each other; the advancement of the whole class of
mammals, or of certain members in this class, to the highest grade
would not lead to their taking the place of fishes. Physiologists
believe that the brain must be bathed by warm blood to be highly
active, and this requires aërial respiration; so that warm-blooded
mammals when inhabiting the water lie under a disadvantage in having to
come continually to the surface to breathe. With fishes, members of the
shark family would not tend to supplant the lancelet; for the lancelet,
as I hear from Fritz Müller, has as sole companion and competitor on
the barren, sandy shore of South Brazil an anomalous annelid. The
three lowest orders of mammals, namely, marsupials, edentata, and
rodents, co-exist in South America in the same region with numerous
monkeys, and probably interfere little with each other. Although
organization, on the whole, may have advanced and be still advancing
throughout the world, yet the scale will always present many degrees
of perfection; for the high advancement of certain whole classes, or
of certain members of each class, does not at all necessarily lead to
the extinction of those groups with which they do not enter into close
competition. In some cases, as we shall hereafter see, lowly organized
forms appear to have been preserved to the present day, from inhabiting
confined or peculiar stations, where they have been subjected to less
severe competition, and where their scanty numbers have retarded the
chance of favorable variations arising.
Finally, I believe that many lowly organized forms now exist throughout
the world, from various causes. In some cases variations or individual
differences of a favorable nature may never have arisen for natural
selection to act on and accumulate. In no case, probably, has time
sufficed for the utmost possible amount of development. In some few
cases there has been what we must call retrogression of organization.
But the main cause lies in the fact that under very simple conditions
of life a high organization would be of no service--possibly would be
of actual disservice, as being of a more delicate nature, and more
liable to be put out of order and injured.
Looking to the first dawn of life, when all organic beings, as we may
believe, presented the simplest structure, how, it has been asked,
could the first steps in the advancement or differentiation of parts
have arisen?
* * * * *
[Page 100.]
As we have no facts to guide us, speculation on the subject is almost
useless. It is, however, an error to suppose that there would be no
struggle for existence, and, consequently, no natural selection, until
many forms had been produced: variations in a single species inhabiting
an isolated station might be beneficial, and thus the whole mass of
individuals might be modified, or two distinct forms might arise. But,
as I remarked toward the close of the Introduction, no one ought to
feel surprised at much remaining as yet unexplained on the origin of
species, if we make due allowance for our profound ignorance on the
mutual relations of the inhabitants of the world at the present time,
and still more so during past ages.
THE AMOUNT OF LIFE MUST HAVE A LIMIT.
[Origin of
Species,
page 101.]
What, then, checks an indefinite increase in the number of species?
The amount of life (I do not mean the number of specific forms)
supported on an area must have a limit, depending so largely as it
does on physical conditions; therefore, if an area be inhabited by
very many species, each or nearly each species will be represented by
few individuals; and such species will be liable to extermination from
accidental fluctuations in the nature of the seasons or in the number
of their enemies. The process of extermination in such cases would
be rapid, whereas the production of new species must always be slow.
Imagine the extreme case of as many species as individuals in England,
and the first severe winter or very dry summer would exterminate
thousands on thousands of species. Rare species, and each species
will become rare if the number of species in any country becomes
indefinitely increased, will, on the principle often explained,
present within a given period few favorable variations; consequently,
the process of giving birth to new specific forms would thus be
retarded. When any species becomes very rare, close interbreeding will
help to exterminate it; authors have thought that this comes into play
in accounting for the deterioration of the aurochs in Lithuania, of red
deer in Scotland, and of bears in Norway, etc. Lastly, and this I am
inclined to think is the most important element, a dominant species,
which has already beaten many competitors in its own home, will tend to
spread and supplant many others. Alph. de Candolle has shown that those
species which spread widely tend generally to spread _very_ widely;
consequently, they will tend to supplant and exterminate several
species in several areas, and thus check the inordinate increase of
specific forms throughout the world. Dr. Hooker has recently shown
that in the southeast corner of Australia, where, apparently, there
are many invaders from different quarters of the globe, the endemic
Australian species have been greatly reduced in number. How much weight
to attribute to these several considerations I will not pretend to
say; but conjointly they must limit in each country the tendency to an
indefinite augmentation of specific forms.
THE BROKEN BRANCHES OF THE TREE OF LIFE.
[Origin of
Species,
page 104.]
The affinities of all the beings of the same class have sometimes been
represented by a great tree. I believe this simile largely speaks the
truth. The green and budding twigs may represent existing species; and
those produced during former years may represent the long succession
of extinct species. At each period of growth all the growing twigs
have tried to branch out on all sides, and to overtop and kill the
surrounding twigs and branches, in the same manner as species and
groups of species have at all times overmastered other species in the
great battle for life. The limbs divided into great branches, and these
into lesser and lesser branches, were themselves once, when the tree
was young, budding twigs; and this connection of the former and present
buds by ramifying branches may well represent the classification of
all extinct and living species in groups subordinate to groups. Of the
many twigs which flourished when the tree was a mere bush, only two or
three, now grown into great branches, yet survive and bear the other
branches; so with the species which lived during long-past geological
periods, very few have left living and modified descendants. From
the first growth of the tree, many a limb and branch has decayed and
dropped off; and these fallen branches of various sizes may represent
those whole orders, families, and genera which have now no living
representatives, and which are known to us only in a fossil state. As
we here and there see a thin straggling branch springing from a fork
low down in a tree, and which by some chance has been favored and is
still alive on its summit, so we occasionally see an animal like the
ornithorhynchus or lepidosiren, which in some small degree connects by
its affinities two large branches of life, and which has apparently
been saved from fatal competition by having inhabited a protected
station. As buds give rise by growth to fresh buds, and these, if
vigorous, branch out and overtop on all sides many a feebler branch, so
by generation I believe it has been with the great Tree of Life, which
fills with its dead and broken branches the crust of the earth, and
covers the surface with its ever-branching and beautiful ramifications.
WHY WE DO NOT FIND TRANSITIONAL FORMS.
[Origin of
Species,
page 134.]
It may be urged that, when several closely-allied species inhabit
the same territory, we surely ought to find at the present time many
transitional forms.
* * * * *
[Page 137.]
I believe that species come to be tolerably well-defined objects, and
do not at any one period present an inextricable chaos of varying
and intermediate links: first, because new varieties are very slowly
formed, for variation is a slow process, and natural selection can do
nothing until favorable individual differences or variations occur,
and until a place in the natural polity of the country can be better
filled by some modification of some one or more of its inhabitants.
And such new places will depend on slow changes of climate, or on the
occasional immigration of new inhabitants, and, probably, in a still
more important degree, on some of the old inhabitants becoming slowly
modified, with the new forms thus produced and the old ones acting and
reacting on each other. So that, in any one region and at any one time,
we ought to see only a few species presenting slight modifications of
structure in some degree permanent; and this assuredly we do see.
Secondly, areas now continuous must often have existed within the
recent period as isolated portions, in which many forms, more
especially among the classes which unite for each birth and wander
much, may have separately been rendered sufficiently distinct to
rank as representative species. In this case, intermediate varieties
between the several representative species and their common parent must
formerly have existed within each isolated portion of the land, but
these links during the process of natural selection will have been
supplanted and exterminated, so that they will no longer be found in a
living state.
Thirdly, when two or more varieties have been formed in different
portions of a strictly continuous area, intermediate varieties will, it
is probable, at first have been formed in the intermediate zones, but
they will generally have had a short duration. For these intermediate
varieties will, from reasons already assigned (namely, from what we
know of the actual distribution of closely-allied or representative
species, and likewise of acknowledged varieties), exist in the
intermediate zones in lesser numbers than the varieties which they tend
to connect. From this cause alone the intermediate varieties will be
liable to accidental extermination; and, during the process of further
modification through natural selection, they will almost certainly
be beaten and supplanted by the forms which they connect; for these
from existing in greater numbers will, in the aggregate, present more
varieties and thus be further improved through natural selection and
gain further advantages.
Lastly, looking not to any one time, but to all time, if my theory be
true, numberless intermediate varieties, linking closely together all
the species of the same group, must assuredly have existed; but the
very process of natural selection constantly tends, as has been so
often remarked, to exterminate the parent-forms and the intermediate
links. Consequently evidence of their former existence could be found
only among fossil remains, which are preserved, as we shall attempt to
show in a future chapter, in an extremely imperfect and intermittent
record.
* * * * *
[Page 283.]
Professor Pictet, in commenting on early transitional forms, and taking
birds as an illustration, can not see how the successive modifications
of the anterior limbs of a supposed prototype could possibly have been
of any advantage. But look at the penguins of the Southern Ocean; have
not these birds their front limbs in this precise intermediate state
of “neither true arms nor true wings”? Yet these birds hold their
place victoriously in the battle for life; for they exist in infinite
numbers and of many kinds. I do not suppose that we here see the real
transitional grades through which the wings of birds have passed; but
what special difficulty is there in believing that it might profit
the modified descendants of the penguin, first to become enabled to
flap along the surface of the sea like the logger-headed duck, and
ultimately to rise from its surface and glide through the air?
* * * * *
[Page 289.]
The several difficulties here discussed, namely--that, though we find
in our geological formations many links between the species which now
exist and which formerly existed, we do not find infinitely numerous
fine transitional forms closely joining them all together; the
sudden manner in which several groups of species first appear in our
European formations--the almost entire absence, as at present known,
of formations rich in fossils beneath the Cambrian strata--are all
undoubtedly of the most serious nature. We see this in the fact that
the most eminent paleontologists, namely, Cuvier, Agassiz, Barrande,
Pictet, Falconer, E. Forbes, etc., and all our greatest geologists, as
Lyell, Murchison, Sedgwick, etc., have unanimously, often vehemently,
maintained the immutability of species. But Sir Charles Lyell now gives
the support of his high authority to the opposite side; and most
geologists and paleontologists are much shaken in their former belief.
Those who believe that the geological record is in any degree perfect
will undoubtedly at once reject the theory. For my part, following
out Lyell’s metaphor, I look at the geological record as a history
of the world imperfectly kept, and written in a changing dialect; of
this history we possess the last volume alone, relating only to two or
three countries. Of this volume, only here and there a short chapter
has been preserved; and of each page, only here and there a few lines.
Each word of the slowly-changing language, more or less different in
the successive chapters, may represent the forms of life which are
entombed in our consecutive formations, and which falsely appear to us
to have been abruptly introduced. On this view, the difficulties above
discussed are greatly diminished, or even disappear.
HOW COULD THE TRANSITIONAL FORM HAVE SUBSISTED?
[Page 138.]
It has been asked by the opponents of such views as I hold, how, for
instance, could a land carnivorous animal have been converted into
one with aquatic habits; for how could the animal in its transitional
state have subsisted? It would be easy to show that there now exist
carnivorous animals presenting close intermediate grades from strictly
terrestrial to aquatic habits; and, as each exists by a struggle for
life, it is clear that each must be well adapted to its place in
nature. Look at the _Mustela vison_ of North America, which has webbed
feet, and which resembles an otter in its fur, short legs, and form of
tail. During the summer this animal dives for and preys on fish, but
during the long winter it leaves the frozen waters, and preys, like
other polecats, on mice and land animals. If a different case had
been taken, and it had been asked how an insectivorous quadruped could
possibly have been converted into a flying bat, the question would have
been far more difficult to answer. Yet I think such difficulties have
little weight.
Here, as on other occasions, I lie under a heavy disadvantage, for,
out of the many striking cases which I have collected, I can give only
one or two instances of transitional habits and structures in allied
species; and of diversified habits, either constant or occasional, in
the same species. And it seems to me that nothing less than a long list
of such cases is sufficient to lessen the difficulty in any particular
case like that of the bat.
WHY NATURE TAKES NO SUDDEN LEAPS.
[Origin of
Species,
page 156.]
Finally, then, although in many cases it is most difficult even to
conjecture by what transitions organs have arrived at their present
state, yet, considering how small the proportion of living and known
forms is to the extinct and unknown, I have been astonished how rarely
an organ can be named, toward which no transitional grade is known to
lead. It certainly is true that new organs, appearing as if created for
some special purpose, rarely or never appear in any being--as indeed
is shown by that old but somewhat exaggerated canon in natural history
of “Natura non facit saltum.” We meet with this admission in the
writings of almost every experienced naturalist; or as Milne-Edwards
has well expressed it, Nature is prodigal in variety, but niggard in
innovation. Why, on the theory of Creation, should there be so much
variety and so little real novelty? Why should all the parts and organs
of many independent beings, each supposed to have been separately
created for its proper place in nature, be so commonly linked together
by graduated steps? Why should not Nature take a sudden leap from
structure to structure? On the theory of natural selection, we can
clearly understand why she should not; for natural selection acts only
by taking advantage of slight successive variations; she can never take
a great and sudden leap, but must advance by short and sure though slow
steps.
IMPERFECT CONTRIVANCES OF NATURE ACCOUNTED FOR.
[Page 163.]
If our reason leads us to admire with enthusiasm a multitude of
inimitable contrivances in nature, this same reason tells us, though
we may easily err on both sides, that some other contrivances are less
perfect. Can we consider the sting of the bee as perfect, which, when
used against many kinds of enemies, can not be withdrawn, owing to the
backward serratures, and thus inevitably causes the death of the insect
by tearing out its viscera?
If we look at the sting of the bee, as having existed in a remote
progenitor as a boring and serrated instrument like that in so many
members of the same great order, and that it has since been modified
but not perfected for its present purpose with the poison originally
adapted for some other object, such as to produce galls, since
intensified, we can perhaps understand how it is that the use of the
sting should so often cause the insect’s own death: for, if on the
whole the power of stinging be useful to the social community, it
will fulfill all the requirements of natural selection, though it may
cause the death of some few members. If we admire the truly wonderful
power of scent by which the males of many insects find their females,
can we admire the production for this single purpose of thousands
of drones, which are utterly useless to the community for any other
purpose, and which are ultimately slaughtered by their industrious and
sterile sisters? It may be difficult, but we ought to admire the savage
instinctive hatred of the queen-bee, which urges her to destroy the
young queens, her daughters, as soon as they are born, or to perish
herself in the combat; for undoubtedly this is for the good of the
community; and maternal love or maternal hatred, though the latter
fortunately is most rare, is all the same to the inexorable principle
of natural selection. If we admire the several ingenious contrivances
by which orchids and many other plants are fertilized through insect
agency, can we consider as equally perfect the elaboration of dense
clouds of pollen by our fir-trees, so that a few granules may be wafted
by chance on to the ovules?
INSTINCTS AS A DIFFICULTY.
[Origin of
Species,
page 205.]
Many instincts are so wonderful that their development will probably
appear to the reader a difficulty sufficient to overthrow my whole
theory. I may here premise that I have nothing to do with the origin of
the mental powers, any more than I have with that of life itself. We
are concerned only with the diversities of instinct and of the other
mental faculties in animals of the same class.
I will not attempt any definition of instinct. It would be easy to
show that several distinct mental actions are commonly embraced by
this term; but every one understands what is meant when it is said
that instinct impels the cuckoo to migrate and to lay her eggs in
other birds’ nests. An action, which we ourselves require experience
to enable us to perform, when performed by an animal, more especially
by a very young one, without experience, and when performed by many
individuals in the same way, without their knowing for what purpose it
is performed, is usually said to be instinctive. But I could show that
none of these characters are universal. A little dose of judgment or
reason, as Pierre Huber expresses it, often comes into play, even with
animals low in the scale of nature.
* * * * *
[Page 206.]
If we suppose any habitual action to become inherited--and it can be
shown that this does sometimes happen--then the resemblance between
what originally was a habit and an instinct becomes so close as not
to be distinguished. If Mozart, instead of playing the piano-forte
at three years old with wonderfully little practice, had played a
tune with no practice at all, he might truly be said to have done
so instinctively. But it would be a serious error to suppose that
the greater number of instincts have been acquired by habit in
one generation, and then transmitted by inheritance to succeeding
generations. It can be clearly shown that the most wonderful instincts
with which we are acquainted, namely, those of the hive-bee and of many
ants, could not possibly have been acquired by habit.
* * * * *
[Page 208.]
Why, it has been asked, if instinct be variable, has it not granted
to the bee “the ability to use some other material when wax was
deficient”? But what other natural material could bees use? They will
work, as I have seen, with wax hardened with vermilion or softened with
lard. Andrew Knight observed that his bees, instead of laboriously
collecting propolis, used a cement of wax and turpentine, with which he
had covered decorticated trees. It has lately been shown that bees,
instead of searching for pollen, will gladly use a very different
substance, namely, oatmeal. Fear of any particular enemy is certainly
an instinctive quality, as may be seen in nestling birds, though it
is strengthened by experience, and by the sight of fear of the same
enemy in other animals. The fear of man is slowly acquired, as I
have elsewhere shown, by the various animals which inhabit desert
islands; and we see an instance of this even in England, in the greater
wildness of all our large birds in comparison with our small birds;
for the large birds have been most persecuted by man. We may safely
attribute the greater wildness of our large birds to this cause; for in
uninhabited islands large birds are not more fearful than small; and
the magpie, so wary in England, is tame in Norway, as is the hooded
crow in Egypt.
SOME INSTINCTS ACQUIRED AND SOME LOST.
[Page 210.]
It may be doubted whether any one would have thought of training a
dog to point, had not some one dog naturally shown a tendency in this
line; and this is known occasionally to happen, as I once saw, in a
pure terrier: the act of pointing is probably, as many have thought,
only the exaggerated pause of an animal preparing to spring on its
prey. When the first tendency to point was once displayed, methodical
selection and the inherited effects of compulsory training in each
successive generation would soon complete the work; and unconscious
selection is still in progress, as each man tries to procure, without
intending to improve the breed, dogs which stand and hunt best. On the
other hand, habit alone in some cases has sufficed; hardly any animal
is more difficult to tame than the young of the wild rabbit; scarcely
any animal is tamer than the young of the tame rabbit; but I can hardly
suppose that domestic rabbits have often been selected for tameness
alone; so that we must attribute at least the greater part of the
inherited change from extreme wildness to extreme tameness to habit and
long-continued close confinement.
Natural instincts are lost under domestication: a remarkable instance
of this is seen in those breeds of fowls which very rarely or never
become “broody,” that is, never wish to sit on their eggs. Familiarity
alone prevents our seeing how largely and how permanently the minds
of our domestic animals have been modified. It is scarcely possible
to doubt that the love of man has become instinctive in the dog. All
wolves, foxes, jackals, and species of the cat genus, when kept tame,
are most eager to attack poultry, sheep, and pigs; and this tendency
has been found incurable in dogs which have been brought home as
puppies from countries such as Tierra del Fuego and Australia, where
the savages do not keep these domestic animals. How rarely, on the
other hand, do our civilized dogs, even when quite young, require
to be taught not to attack poultry, sheep, and pigs! No doubt they
occasionally do make an attack, and are then beaten; and, if not cured,
they are destroyed; so that habit and some degree of selection have
probably concurred in civilizing by inheritance our dogs. On the other
hand, young chickens have lost, wholly by habit, that fear of the dog
and cat which no doubt was originally instinctive in them; for I am
informed by Captain Hutton that the young chickens of the parent-stock,
the _Gallus bankiva_, when reared in India under a hen, are at first
excessively wild. So it is with young pheasants reared in England under
a hen. It is not that chickens have lost all fear, but fear only of
dogs and cats, for if the hen gives the danger-chuckle, they will run
(more especially young turkeys) from under her, and conceal themselves
in the surrounding grass or thickets; and this is evidently done for
the instinctive purpose of allowing, as we see in wild ground-birds,
their mother to fly away. But this instinct retained by our chickens
has become useless under domestication, for the mother-hen has almost
lost by disuse the power of flight.
Hence, we may conclude that, under domestication, instincts have been
acquired, and natural instincts have been lost, partly by habit,
and partly by man selecting and accumulating, during successive
generations, peculiar mental habits and actions, which at first
appeared from what we must in our ignorance call an accident.
INNUMERABLE LINKS NECESSARILY LOST.
[Origin of
Species,
page 264.]
The main cause of innumerable intermediate links not now occurring
everywhere throughout nature depends on the very process of natural
selection, through which new varieties continually take the places of
and supplant their parent-forms. But just in proportion as this process
of extermination has acted on an enormous scale, so must the number of
intermediate varieties, which have formerly existed, be truly enormous.
Why, then, is not every geological formation and every stratum full
of such intermediate links? Geology assuredly does not reveal any
such finely-graduated organic chain; and this, perhaps, is the most
obvious and serious objection which can be urged against the theory.
The explanation lies, as I believe, in the extreme imperfection of the
geological record.
In the first place, it should always be borne in mind what sort of
intermediate forms must, on the theory, have formerly existed. I have
found it difficult, when looking at any two species, to avoid picturing
to myself forms _directly_ intermediate between them. But this is a
wholly false view; we should always look for forms intermediate between
each species and a common but unknown progenitor; and the progenitor
will generally have differed in some respects from all its modified
descendants. To give a simple illustration: the fantail and pouter
pigeons are both descended from the rock-pigeon; if we possessed all
the intermediate varieties which have ever existed, we should have an
extremely close series between both and the rock-pigeon; but we should
have no varieties directly intermediate between the fantail and pouter;
none, for instance, combining a tail somewhat expanded with a crop
somewhat enlarged, the characteristic features of these two breeds.
These two breeds, moreover, have become so much modified, that, if we
had no historical or indirect evidence regarding their origin, it would
not have been possible to have determined, from a mere comparison of
their structure with that of the rock-pigeon, _C. livia_, whether they
had descended from this species or from some other allied form, such as
_C. oenas_.
* * * * *
[Page 265.]
It is just possible by the theory, that one of two living forms might
have descended from the other; for instance, a horse from a tapir; and
in this case _direct_ intermediate links will have existed between
them. But such a case would imply that one form had remained for a
very long period unaltered, while its descendants had undergone a vast
amount of change; and the principle of competition between organism and
organism, between child and parent, will render this a very rare event;
for in all cases the new and improved forms of life tend to supplant
the old and unimproved forms.
By the theory of natural selection all living species have been
connected with the parent-species of each genus, by differences not
greater than we see between the natural and domestic varieties of
the same species at the present day; and these parent-species, now
generally extinct, have in their turn been similarly connected with
more ancient forms; and so on backward, always converging to the common
ancestor of each great class. So that the number of intermediate and
transitional links, between all living and extinct species, must have
been inconceivably great. But assuredly, if this theory be true, such
have lived upon the earth.
PLENTY OF TIME FOR THE NECESSARY GRADATIONS.
[Page 266.]
Independently of our not finding fossil remains of such infinitely
numerous connecting links, it may be objected that time can not have
sufficed for so great an amount of organic change, all changes having
been effected slowly. It is hardly possible for me to recall to the
reader who is not a practical geologist the facts leading the mind
feebly to comprehend the lapse of time. He who can read Sir Charles
Lyell’s grand work on the “Principles of Geology,” which the future
historian will recognize as having produced a revolution in natural
science, and yet does not admit how vast have been the past periods of
time, may at once close this volume.
* * * * *
[Page 269.]
When geologists look at large and complicated phenomena, and then at
the figures representing several million years, the two produce a
totally different effect on the mind, and the figures are at once
pronounced too small. In regard to subaërial denudation, Mr. Croll
shows, by calculating the known amount of sediment annually brought
down by certain rivers, relatively to their areas of drainage, that
one thousand feet of solid rock, as it became gradually disintegrated,
would thus be removed from the mean level of the whole area in the
course of six million years. This seems an astonishing result, and
some considerations lead to the suspicion that it may be too large,
but even if halved or quartered it is still very surprising. Few of
us, however, know what a million really means: Mr. Croll gives the
following illustration: take a narrow strip of paper, eighty-three feet
four inches in length, and stretch it along the wall of a large hall;
then mark off at one end the tenth of an inch. This tenth of an inch
will represent one hundred years, and the entire strip a million years.
But let it be borne in mind, in relation to the subject of this work,
what a hundred years implies, represented as it is by a measure utterly
insignificant in a hall of the above dimensions. Several eminent
breeders, during a single lifetime, have so largely modified some of
the higher animals, which propagate their kind much more slowly than
most of the lower animals, that they have formed what well deserves
to be called a new sub-breed. Few men have attended with due care to
any one strain for more than half a century, so that a hundred years
represents the work of two breeders in succession.
* * * * *
[Page 270.]
Now let us turn to our richest geological museums, and what a paltry
display we behold! That our collections are imperfect is admitted by
every one. The remark of that admirable paleontologist, Edward Forbes,
should never be forgotten, namely, that very many fossil species are
known and named from single and often broken specimens, or from a few
specimens collected on some one spot. Only a small portion of the
surface of the earth has been geologically explored, and no part with
sufficient care, as the important discoveries made every year in Europe
prove. No organism wholly soft can be preserved. Shells and bones decay
and disappear when left on the bottom of the sea, where sediment is not
accumulating. We probably take a quite erroneous view, when we assume
that sediment is being deposited over nearly the whole bed of the sea,
at a rate sufficiently quick to imbed and preserve fossil remains.
Throughout an enormously large proportion of the ocean, the bright blue
tint of the water bespeaks its purity. The many cases on record of a
formation conformably covered, after an immense interval of time, by
another and later formation, without the underlying bed having suffered
in the interval any wear and tear, seem explicable only on the view
of the bottom of the sea not rarely lying for ages in an unaltered
condition. The remains which do become imbedded, if in sand or gravel,
will, when the beds are upraised, generally be dissolved by the
percolation of rain-water charged with carbonic acid. Some of the many
kinds of animals which live on the beach between high and low water
mark seem to be rarely preserved. For instance, the several species of
the _Chthamalinæ_ (a sub-family of sessile cirripeds) coat the rocks
all over the world in infinite numbers: they are all strictly littoral,
with the exception of a single Mediterranean species, which inhabits
deep water, and this has been found fossil in Sicily, whereas not
one other species has hitherto been found in any tertiary formation;
yet it is known that the genus _Chthamalus_ existed during the Chalk
period. Lastly, many great deposits, requiring a vast length of time
for their accumulation, are entirely destitute of organic remains,
without our being able to assign any reason; one of the most striking
instances is that of the Flysch formation, which consists of shale and
sandstone, several thousand, occasionally even six thousand, feet in
thickness, and extending for at least three hundred miles from Vienna
to Switzerland; and, although this great mass has been most carefully
searched, no fossils, except a few vegetable remains, have been found.
WIDE INTERVALS OF TIME BETWEEN THE GEOLOGICAL FORMATIONS.
[Page 271.]
But the imperfection in the geological record largely results from
another and more important cause than any of the foregoing; namely,
from the several formations being separated from each other by wide
intervals of time. This doctrine has been emphatically admitted by
many geologists and paleontologists, who, like E. Forbes, entirely
disbelieve in the change of species. When we see the formations
tabulated in written works, or when we follow them in nature, it is
difficult to avoid believing that they are closely consecutive. But
we know, for instance, from Sir R. Murchison’s great work on Russia,
what wide gaps there are in that country between the superimposed
formations; so it is in North America, and in many other parts of
the world. The most skillful geologist, if his attention had been
confined exclusively to these large territories, would never have
suspected that, during the periods which were blank and barren in his
own country, great piles of sediment, charged with new and peculiar
forms of life, had elsewhere been accumulated. And if, in each separate
territory, hardly any idea can be formed of the length of time which
has elapsed between the consecutive formations, we may infer that this
could nowhere be ascertained. The frequent and great changes in the
mineralogical composition of consecutive formations, generally implying
great changes in the geography of the surrounding lands, whence the
sediment was derived, accord with the belief of vast intervals of time
having elapsed between each formation.
* * * * *
[Page 278.]
It is all-important to remember that naturalists have no golden rule
by which to distinguish species and varieties; they grant some little
variability to each species, but, when they meet with a somewhat
greater amount of difference between any two forms, they rank both
as species, unless they are enabled to connect them together by the
closest intermediate gradations; and this, from the reasons just
assigned, we can seldom hope to effect in any one geological section.
Supposing B and C to be two species, and a third, A, to be found in an
older and underlying bed; even if A were strictly intermediate between
B and C, it would simply be ranked as a third and distinct species,
unless at the same time it could be closely connected by intermediate
varieties with either one or both forms. Nor should it be forgotten,
as before explained, that A might be the actual progenitor of B and C,
and yet would not necessarily be strictly intermediate between them
in all respects. So that we might obtain the parent-species and its
several modified descendants from the lower and upper beds of the same
formation, and, unless we obtained numerous transitional gradations, we
should not recognize their blood-relationship, and should consequently
rank them as distinct species.
SUDDEN APPEARANCE OF GROUPS OF ALLIED SPECIES.
[Origin of
Species,
page 282.]
The abrupt manner in which whole groups of species suddenly appear
in certain formations has been urged by several paleontologists--for
instance, by Agassiz, Pictet, and Sedgwick--as a fatal objection to the
belief in the transmutation of species. If numerous species, belonging
to the same genera or families, have really started into life at once,
the fact would be fatal to the theory of evolution through natural
selection. For the development by this means of a group of forms, all
of which are descended from some one progenitor, must have been an
extremely slow process; and the progenitors must have lived long before
their modified descendants. But we continually overrate the perfection
of the geological record, and falsely infer, because certain genera or
families have not been found beneath a certain stage, that they did
not exist before that stage. In all cases positive paleontological
evidence may be implicitly trusted; negative evidence is worthless,
as experience has so often shown. We continually forget how large the
world is, compared with the area over which our geological formations
have been carefully examined; we forget that groups of species may
elsewhere have long existed, and have slowly multiplied, before they
invaded the ancient archipelagoes of Europe and the United States. We
do not make due allowance for the intervals of time which have elapsed
between our consecutive formations--longer, perhaps, in many cases
than the time required for the accumulation of each formation. These
intervals will have given time for the multiplication of species from
some one parent-form; and, in the succeeding formation, such groups or
species will appear as if suddenly created.
HOW LITTLE WE KNOW OF FORMER INHABITANTS OF THE WORLD.
[Page 283.]
Even in so short an interval as that between the first and second
edition of Pictet’s great work on Paleontology, published in 1844–’46
and in 1853–’57, the conclusions on the first appearance and
disappearance of several groups of animals have been considerably
modified; and a third edition would require still further changes. I
may recall the well-known fact that in geological treatises, published
not many years ago, mammals were always spoken of as having abruptly
come in at the commencement of the tertiary[B] series. And now one
of the richest known accumulations of fossil mammals belongs to the
middle of the secondary series; and true mammals have been discovered
in the new red sandstone at nearly the commencement of this great
series. Cuvier used to urge that no monkey occurred in any tertiary
stratum; but now extinct species have been discovered in India, South
America, and in Europe, as far back as the Miocene stage. Had it not
been for the rare accident of the preservation of footsteps in the
new red sandstone of the United States, who would have ventured to
suppose that no less than at least thirty different bird-like animals,
some of gigantic size, existed during that period? Not a fragment of
bone has been discovered in these beds. Not long ago, paleontologists
maintained that the whole class of birds came suddenly into existence
during the Eocene period; but now we know, on the authority of
Professor Owen, that a bird certainly lived during the deposition
of the upper greensand; and still more recently, that strange bird,
the archeopteryx, with a long, lizard-like tail, bearing a pair of
feathers on each joint, and with its wings furnished with two free
claws, has been discovered in the oölitic slates of Solenhofen. Hardly
any recent discovery shows more forcibly than this, how little we as
yet know of the former inhabitants of the world.
[B] TERTIARY.--The latest geological epoch, immediately
preceding the establishment of the present order of things.
THE EXTINCTION OF SPECIES INVOLVED IN MYSTERY.
[Origin of
Species,
page 294.]
The extinction of species has been involved in the most gratuitous
mystery. Some authors have even supposed that as the individual has
a definite length of life, so have species a definite duration. No
one can have marveled more than I have done at the extinction of
species. When I found in La Plata the tooth of a horse imbedded with
the remains of mastodon, megatherium, toxodon, and other extinct
monsters, which all co-existed with still living shells at a very late
geological period, I was filled with astonishment; for, seeing that
the horse, since its introduction by the Spaniards into South America,
has run wild over the whole country and has increased in numbers at
an unparalleled rate, I asked myself what could so recently have
exterminated the former horse under conditions of life apparently so
favorable. But my astonishment was groundless. Professor Owen soon
perceived that the tooth, though so like that of the existing horse,
belonged to an extinct species. Had this horse been still living, but
in some degree rare, no naturalist would have felt the least surprise
at its rarity; for rarity is the attribute of a vast number of species
of all classes, in all countries. If we ask ourselves why this or
that species is rare, we answer that something is unfavorable in its
conditions of life; but what that something is we can hardly ever
tell. On the supposition of the fossil horse still existing as a rare
species, we might have felt certain, from the analogy of all other
mammals, even of the slow-breeding elephant, and from the history of
the naturalization of the domestic horse in South America, that under
more favorable conditions it would in a very few years have stocked
the whole continent. But we could not have told what the unfavorable
conditions were which checked its increase, whether some one or several
contingencies, and at what period of the horse’s life, and in what
degree, they severally acted. If the conditions had gone on, however
slowly, becoming less and less favorable, we assuredly should not have
perceived the fact, yet the fossil horse would certainly have become
rarer and rarer, and finally extinct;--its place being seized on by
some more successful competitor.
It is most difficult always to remember that the increase of every
creature is constantly being checked by unperceived hostile agencies;
and that these same unperceived agencies are amply sufficient to cause
rarity, and finally extinction. So little is this subject understood
that I have heard surprise repeatedly expressed at such great monsters
as the mastodon and the more ancient dinosaurians having become
extinct; as if mere bodily strength gave victory in the battle of life.
Mere size, on the contrary, would in some cases determine, as has
been remarked by Owen, quicker extermination from the greater amount
of requisite food. Before man inhabited India or Africa, some cause
must have checked the continued increase of the existing elephant. A
highly capable judge, Dr. Falconer, believes that it is chiefly insects
which, from incessantly harassing and weakening the elephant in India,
check its increase; and this was Bruce’s conclusion with respect to
the African elephant in Abyssinia. It is certain that insects and
blood-sucking bats determine the existence of the larger naturalized
quadrupeds in several parts of South America.
* * * * *
[Page 295.]
I may repeat what I published in 1845, namely, that to admit that
species generally become rare before they become extinct--to feel no
surprise at the rarity of a species, and yet to marvel greatly when the
species ceases to exist, is much the same as to admit that sickness
in the individual is the forerunner of death--to feel no surprise at
sickness, but, when the sick man dies, to wonder and to suspect that he
died by some deed of violence.
DEAD LINKS BETWEEN LIVING SPECIES.
[Page 302.]
No one will deny that the Hipparion is intermediate between the
existing horse and certain older ungulate forms. What a wonderful
connecting link in the chain of mammals is the Typotherium from South
America, as the name given to it by Professor Gervais expresses, and
which can not be placed in any existing order! The Sirenia form a very
distinct group of mammals, and one of the most remarkable peculiarities
in the existing dugong and lamentin is the entire absence of hind
limbs, without even a rudiment being left; but the extinct Halitherium
had, according to Professor Flower, an ossified thigh-bone “articulated
to a well-defined acetabulum in the pelvis,” and it thus makes some
approach to ordinary hoofed quadrupeds, to which the Sirenia are in
other respects allied. The cetaceans or whales are widely different
from all other mammals, but the tertiary Zeuglodon and Squalodon, which
have been placed by some naturalists in an order by themselves, are
considered by Professor Huxley to be undoubtedly cetaceans, “and to
constitute connecting links with the aquatic carnivora.”
Even the wide interval between birds and reptiles has been shown
by the naturalist just quoted to be partially bridged over in the
most unexpected manner, on the one hand, by the ostrich and extinct
Archeopteryx, and on the other hand, by the Compsognathus, one of
the dinosaurians--that group which includes the most gigantic of all
terrestrial reptiles. Turning to the Invertebrata, Barrande asserts,
and a higher authority could not be named, that he is every day taught
that, although palæozoic animals can certainly be classed under
existing groups, yet that at this ancient period the groups were not so
distinctly separated from each other as they now are.
Some writers have objected to any extinct species, or group of species,
being considered as intermediate between any two living species or
groups of species. If by this term it is meant that an extinct form
is directly intermediate in all its characters between two living
forms or groups, the objection is probably valid. But in a natural
classification many fossil species certainly stand between living
species, and some extinct genera between living genera, even between
genera belonging to distinct families. The most common case, especially
with respect to very distinct groups, such as fish and reptiles, seems
to be that, supposing them to be distinguished at the present day by a
score of characters, the ancient members are separated by a somewhat
lesser number of characters; so that the two groups formerly made a
somewhat nearer approach to each other than they now do.
LIVING DESCENDANTS OF FOSSIL SPECIES.
[Page 311.]
It may be asked in ridicule, whether I suppose that the megatherium
and other allied huge monsters, which formerly lived in South America,
have left behind them the sloth, armadillo, and ant-eater, as their
degenerate descendants. This can not for an instant be admitted. These
huge animals have become wholly extinct, and have left no progeny. But
in the caves of Brazil there are many extinct species which are closely
allied in size and in all other characters to the species still living
in South America; and some of these fossils may have been the actual
progenitors of the living species. It must not be forgotten that, on
our theory, all the species of the same genus are the descendants of
some one species; so that, if six genera, each having eight species,
be found in one geological formation, and in a succeeding formation
there be six other allied or representative genera each with the
same number of species, then we may conclude that generally only one
species of each of the older genera has left modified descendants,
which constitute the new genera containing the several species;
the other seven species of each old genus having died out and left
no progeny. Or, and this will be a far commoner case, two or three
species in two or three alone of the six older genera will be the
parents of the new genera: the other species and the other whole genera
having become utterly extinct. In failing orders, with the genera
and species decreasing in numbers as is the case with the Edentata
of South America, still fewer genera and species will leave modified
blood-descendants.
UNNECESSARY TO EXPLAIN THE CAUSE OF EACH INDIVIDUAL DIFFERENCE.
[Animals and
Plants, vol.
ii, page 425.]
In accordance with the views maintained by me in this work and
elsewhere, not only various domestic races, but the most distinct
genera and orders within the same great class--for instance, mammals,
birds, reptiles, and fishes--are all the descendants of one common
progenitor, and we must admit that the whole vast amount of difference
between these forms has primarily arisen from simple variability. To
consider the subject under this point of view is enough to strike
one dumb with amazement. But our amazement ought to be lessened when
we reflect that beings almost infinite in number, during an almost
infinite lapse of time, have often had their whole organization
rendered in some degree plastic, and that each slight modification of
structure which was in any way beneficial under excessively complex
conditions of life has been preserved, while each which was in any
way injurious has been rigorously destroyed. And the long-continued
accumulation of beneficial variations will infallibly have led to
structures as diversified, as beautifully adapted for various purposes
and as excellently co-ordinated, as we see in the animals and plants
around us. Hence I have spoken of selection as the paramount power,
whether applied by man to the formation of domestic breeds, or by
nature to the production of species.
If an architect were to rear a noble and commodious edifice, without
the use of cut stone, by selecting from the fragments at the base of a
precipice wedge-formed stones for his arches, elongated stones for his
lintels, and flat stones for his roof, we should admire his skill and
regard him as the paramount power. Now, the fragments of stone, though
indispensable to the architect, bear to the edifice built by him the
same relation which the fluctuating variations of organic beings bear
to the varied and admirable structures ultimately acquired by their
modified descendants.
Some authors have declared that natural selection explains nothing,
unless the precise cause of each slight individual difference be made
clear. If it were explained to a savage utterly ignorant of the art of
building, how the edifice had been raised stone upon stone, and why
wedge-formed fragments were used for the arches, flat stones for the
roof, etc., and if the use of each part and of the whole building were
pointed out, it would be unreasonable if he declared that nothing had
been made clear to him, because the precise cause of the shape of each
fragment could not be told. But this is a nearly parallel case with
the objection that selection explains nothing, because we know not the
cause of each individual difference in the structure of each being.
The shape of the fragments of stone at the base of our precipice may be
called accidental, but this is not strictly correct; for the shape of
each depends on a long sequence of events, all obeying natural laws;
on the nature of the rock, on the lines of deposition or cleavage, on
the form of the mountain, which depends on its upheaval and subsequent
denudation, and lastly on the storm or earthquake which throws down the
fragments. But in regard to the use to which the fragments may be put,
their shape may be strictly said to be accidental.
“FACE TO FACE WITH AN INSOLUBLE DIFFICULTY.”
[Page 427.]
And here we are led to face a great difficulty, in alluding to which I
am aware that I am traveling beyond my proper province. An omniscient
Creator must have foreseen every consequence which results from the
laws imposed by him. But can it be reasonably maintained that the
Creator intentionally ordered, if we use the words in any ordinary
sense, that certain fragments of rock should assume certain shapes so
that the builder might erect his edifice? If the various laws which
have determined the shape of each fragment were not predetermined for
the builder’s sake, can it be maintained with any greater probability
that he specially ordained for the sake of the breeder each of the
innumerable variations in our domestic animals and plants--many of
these variations being of no service to man, and not beneficial, far
more often injurious, to the creatures themselves? Did he ordain that
the crop and tail-feathers of the pigeon should vary in order that the
fancier might make his grotesque pouter and fantail breeds? Did he
cause the frame and mental qualities of the dog to vary in order that a
breed might be formed of indomitable ferocity, with jaws fitted to pin
down the bull for man’s brutal sport? But if we give up the principle
in one case--if we do not admit that the variations of the primeval dog
were intentionally guided in order that the greyhound, for instance,
that perfect image of symmetry and vigor, might be formed--no shadow of
reason can be assigned for the belief that variations, alike in nature
and the result of the same general laws, which have been the groundwork
through natural selection of the formation of the most perfectly
adapted animals in the world, man included, were intentionally and
specially guided. However much we may wish it, we can hardly follow
Professor Asa Gray in his belief “that variation has been led along
certain beneficial lines,” like a stream “along definite and useful
lines of irrigation.” If we assume that each particular variation was
from the beginning of all time preordained, then that plasticity of
organization, which leads to many injurious deviations of structure,
as well as the redundant power of reproduction which inevitably leads
to a struggle for existence, and, as a consequence, to the natural
selection or survival of the fittest, must appear to us superfluous
laws of nature. On the other hand, an omnipotent and omniscient Creator
ordains everything and foresees everything. Thus we are brought face
to face with a difficulty as insoluble as is that of free-will and
predestination.
WHY DISTASTEFUL?
[Descent of
Man, page 618.]
The main conclusion arrived at in this work, namely, that man is
descended from some lowly organized form, will, I regret to think, be
highly distasteful to many. But there can hardly be a doubt that we
are descended from barbarians. The astonishment which I felt on first
seeing a party of Fuegians on a wild and broken shore will never be
forgotten by me, for the reflection at once rushed into my mind--such
were our ancestors. These men were absolutely naked and bedaubed
with paint, their long hair was tangled, their mouths frothed with
excitement, and their expression was wild, startled, and distrustful.
They possessed hardly any arts, and like wild animals lived on what
they could catch; they had no government, and were merciless to
every one not of their own small tribe. He who has seen a savage in
his native land will not feel much shame, if forced to acknowledge
that the blood of some more humble creature flows in his veins. For
my own part I would as soon be descended from that heroic little
monkey, who braved his dreaded enemy in order to save the life of his
keeper, or from that old baboon, who, descending from the mountains,
carried away in triumph his young comrade from a crowd of astonished
dogs--as from a savage who delights to torture his enemies, offers up
bloody sacrifices, practices infanticide without remorse, treats his
wives like slaves, knows no decency, and is haunted by the grossest
superstitions.
Man may be excused for feeling some pride at having risen, though not
through his own exertions, to the very summit of the organic scale; and
the fact of his having thus risen, instead of having been aboriginally
placed there, may give him hope for a still higher destiny in the
distant future. But we are not here concerned with hopes or fears, only
with the truth as far as our reason permits us to discover it; and I
have given the evidence to the best of my ability. We must, however,
acknowledge, as it seems to me, that man with all his noble qualities,
with sympathy which feels for the most debased, with benevolence which
extends not only to other men but to the humblest living creature,
with his godlike intellect which has penetrated into the movements and
constitution of the solar system--with all these exalted powers--man
still bears in his bodily frame the indelible stamp of his lowly origin.
“ACCORDS BETTER WITH WHAT WE KNOW OF THE CREATOR’S LAWS.”
[Origin of
Species,
page 428.]
Authors of the highest eminence seem to be fully satisfied with the
view that each species has been independently created. To my mind
it accords better with what we know of the laws impressed on matter
by the Creator, that the production and extinction of the past and
present inhabitants of the world should have been due to secondary
causes, like those determining the birth and death of the individual.
When I view all beings not as special creations, but as the lineal
descendants of some few beings which lived long before the first bed of
the Cambrian system was deposited, they seem to me to become ennobled.
Judging from the past, we may safely infer that not one living species
will transmit its unaltered likeness to a distant futurity. And of the
species now living very few will transmit progeny of any kind to a
far distant futurity; for the manner in which all organic beings are
grouped, shows that the greater number of species in each genus, and
all the species in many genera, have left no descendants, but have
become utterly extinct. We can so far take a prophetic glance into
futurity as to foretell that it will be the common and widely-spread
species, belonging to the larger and dominant groups within each class,
which will ultimately prevail and procreate new and dominant species.
As all the living forms of life are the lineal descendants of those
which lived long before the Cambrian epoch, we may feel certain that
the ordinary succession by generation has never once been broken, and
that no cataclysm has desolated the whole world. Hence we may look with
some confidence to a secure future of great length. And as natural
selection works solely by and for the good of each being, all corporeal
and mental endowments will tend to progress toward perfection.
THE GRANDEUR OF THIS VIEW OF LIFE.
[Page 429.]
It is interesting to contemplate a tangled bank, clothed with many
plants of many kinds, with birds singing on the bushes, with various
insects flitting about, and with worms crawling through the damp earth,
and to reflect that these elaborately constructed forms, so different
from each other, and dependent upon each other in so complex a manner,
have all been produced by laws acting around us. These laws, taken in
the largest sense, being growth with reproduction; inheritance which
is almost implied by reproduction; variability from the indirect and
direct action of the conditions of life, and from use and disuse: a
ratio of increase so high as to lead to a struggle for life, and as a
consequence to natural selection, entailing divergence of character and
the extinction of less-improved forms. Thus, from the war of nature,
from famine and death, the most exalted object which we are capable
of conceiving, namely, the production of the higher animals, directly
follows. There is grandeur in this view of life, with its several
powers, having been originally breathed by the Creator into a few forms
or into one; and that, while this planet has gone cycling on according
to the fixed law of gravity, from so simple a beginning endless forms
most beautiful and most wonderful have been and are being evolved.
NOT INCOMPATIBLE WITH THE BELIEF IN IMMORTALITY.
[Descent of
Man, page 612.]
I am aware that the assumed instinctive belief in God has been used by
many persons as a rash argument for his existence. But this is a rash
argument, as we should thus be compelled to believe in the existence
of many cruel and malignant spirits, only a little more powerful than
man; for the belief in them is far more general than in a beneficent
Deity. The idea of a universal and beneficent Creator does not seem to
arise in the mind of man, until he has been elevated by long-continued
culture.
He who believes in the advancement of man from some low organized
form, will naturally ask, How does this bear on the belief in the
immortality of the soul? The barbarous races of man, as Sir J. Lubbock
has shown, possess no clear belief of this kind; but arguments derived
from the primeval beliefs of savages are, as we have just seen, of
little or no avail. Few persons feel any anxiety from the impossibility
of determining at what precise period in the development of the
individual, from the first trace of a minute germinal vesicle, man
becomes an immortal being; and there is no greater cause for anxiety
because the period can not possibly be determined in the gradually
ascending organic scale.
I am aware that the conclusions arrived at in this work will be
denounced by some as highly irreligious; but he who denounces them is
bound to show why it is more irreligious to explain the origin of man
as a distinct species by descent from some lower form, through the
laws of variation and natural selection, than to explain the birth of
the individual through the laws of ordinary reproduction. The birth
both of the species and of the individual are equally parts of that
grand sequence of events, which our minds refuse to accept as the
result of blind chance. The understanding revolts at such a conclusion,
whether or not we are able to believe that every slight variation of
structure--the union of each pair in marriage--the dissemination of
each seed--and other such events, have all been ordained for some
special purpose.
* * * * *
[Journal of
Researches,
page 503.]
Among the scenes which are deeply impressed on my mind, none exceed in
sublimity the primeval forests undefaced by the hand of man; whether
those of Brazil, where the powers of life are predominant, or those
of Tierra del Fuego, where death and decay prevail. Both are temples
filled with the varied productions of the God of Nature; no one can
stand in these solitudes unmoved, and not feel that there is more in
man than the mere breath of his body.
THE END.
Transcriber’s Notes
Punctuation, hyphenation, and spelling were made consistent when a
predominant preference was found in the original book; otherwise they
were not changed.
Simple typographical errors were corrected; unbalanced quotation marks
were remedied when the change was obvious or could be determined by
reference to Darwin’s original books; and otherwise left unbalanced.
*** End of this LibraryBlog Digital Book "Darwinism stated by Darwin himself: Characteristic passages from the writings of Charles Darwin" ***
Copyright 2023 LibraryBlog. All rights reserved.