White Female, Part of whose Skin resembles that of a Negro." In this
paper the author distinctly recognized the principle of natural
selection, but applied it only to the races of man, and in man only to
certain characters. After remarking that negroes and mulattoes enjoy an
immunity from certain tropical diseases, he observed, first, that all
animals tend to vary in some degree, and, secondly, that
agriculturalists improve their domesticated animals by selection. He
added that what is done in the latter case by art seems to be done with
equal efficacy, though more slowly, by nature in the formation of
varieties of mankind fitted for the countries which they inhabit. Again
in 1831 Mr. Patrick Matthew published a work on "Naval Timber and
Arboriculture," in which he put forth precisely the same view
concerning the origin of species as that propounded by Mr. Wallace and
by Darwin. Unfortunately for himself, the view was cursorily suggested
in scattered passages of an appendix to a work on a different subject,
so that it remained unnoticed until Mr. Matthew himself drew attention
to it in 1860, after the publication of the "Origin of Species." We
observe finally that Mr. Herbert Spencer, in an essay published in 1852,
and republished six years later, contrasted the theories of the creation
and the development of organic beings. He argued from the analogy of
domestic productions, from the changes which the embryos of many species
undergo, from the difficulty of distinguishing species and varieties,
and from the principle of general gradation, that species have been
modified; and he attributed the modification to the change of
circumstances.
The two volumes comprising the "Origin of Species" constitute, as the
author said, one long argument. It is, of course, impossible in the
space at our command to recapitulate in detail even the leading facts
and inferences which are brought forward to prove that species have been
modified during a long course of descent. We must confine ourselves to a
succinct statement of the author's general conclusions. What he
undertakes to prove is that the modification of species during a long
course of descent has been effected chiefly through the natural
selection of numerous successive slight favorable variations, aided in
an important manner by the inherited effects of the use and disuse of
parts; and in an unimportant manner,--that is, in relation to adaptive
structures, whether past or present, by the direct action of external
conditions, and by variations which seem to us, in our ignorance, to
arise spontaneously. It should be observed that Darwin does not
attribute the modification exclusively to natural selection. What he
asserts is: "I am convinced that natural selection has been the main,
but not the exclusive, means of modification." He submits that a false
theory would hardly explain in so satisfactory a manner as does the
theory of natural selection the several large classes of facts
marshalled in the two volumes now under review. If it be objected that
this is an unsafe method of arguing, Darwin rejoins that it is a method
usual in judging of the common events of life, and has often been used
by the greatest natural philosophers. The undulatory theory of light,
for instance, has thus been arrived at; and the belief in the revolution
of the earth on its own axis was, until lately, supported by scarcely
any direct evidence. It is no valid objection to the Darwinian theory of
the origin of species that science as yet throws no light on the far
higher problem of the essence or origin of life. Neither has any one
explained what is the essence of the attraction of gravity, though
nobody now objects to following out the results consequent on this
unknown element of attraction.
Why, it may be asked, did nearly all the most eminent naturalists and
geologists until recently decline to believe in the mutability of
species? Darwin replies that the belief that species were immutable
productions was almost unavoidable as long as the history of the world
was thought to be of short duration. Even now that we have acquired some
idea of the lapse of time, men are too apt to assume without proof that
the geological record is so perfect that it would have afforded plain
evidence of the mutation of species if they had really undergone
mutation. The chief cause, however, of the once-prevalent unwillingness
to admit that one species has given birth to other and distinct species
is the fact that men are slow to admit great changes of which they do
not see the steps. The difficulty is the same which was experienced by
many geologists when Lyell first insisted that long lines of inland
cliffs had been formed and great valleys excavated, not by catastrophes,
but by the slow-moving agencies which we see still at work. The human
mind cannot grasp the full meaning of the term of even a million years;
cannot add up and perceive the full effects of many slight variations
accumulated during an almost infinite number of generations.
When the first edition of the "Origin of Species" was published in 1859,
Darwin wrote that he by no means expected to convince experienced
naturalists whose minds were stocked with a multitude of facts, all
regarded during a long course of years from a point of view directly
opposite to his. He looked forward with confidence, however, to the
future, to young and rising naturalists, who would be able to view both
sides of the question with impartiality. He predicted that, when the
conclusions reached by him and by Mr. Wallace concerning the origin of
species should be generally accepted, there would be a considerable
revolution in natural history. Naturalists, for instance, would be
forced 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, though they are not now, thus connected. It might thus
come to pass that forms generally acknowledged in 1859 to be merely
varieties, would thereafter be thought worthy of specific names; in
which case scientific and common language would come into accordance. In
short, Darwin looked forward to the time when species would have to be
treated in the same manner as genera are treated by those naturalists
who admit that genera are merely artificial combinations made for
convenience.
Darwin also foresaw that when his theory of the origin of species should
be adopted, other and more general departments of natural history would
rise greatly in interest. The terms used by naturalists--such terms as
affinity, relationship, community of type, paternity, morphology,
adaptive characters, rudimentary and abortive organs, etc.--would cease
to be metaphorical, and would have a plain signification. "When," he
wrote, "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." Once more: "When
we can feel assured that all the individuals of the same species, and
all the closely allied species of most genera, have within a not very
remote period descended from one parent, and have migrated from some one
birthplace; and when we better know the many means of migration, then,
by the light which geology now throws, and will continue to throw, on
former changes of climate and of the level of the land, we shall surely
be enabled to trace in an admirable manner the former migrations of the
inhabitants of the whole world."
When Darwin published the "Origin of Species," he was aware that
theologians and philosophers seemed to be fully satisfied with the view
that each species had been independently created, and was immutable. To
his own mind, however, it accorded better with what was known 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," he said, "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." And again: "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 slowly by
and for the good of each being, all corporeal and mental endowments will
tend to progress towards perfection."
For his own part, Darwin could see no good reason why the views
propounded in the two volumes comprising the "Origin of Species" should
shock the religious feelings of any one. Touching the likelihood of
such a result, he reassured himself by recalling the fact that the
greatest discovery ever made by man--namely, the law of the attraction
of gravitation--was attacked by Leibnitz "as subversive of natural, and
inferentially, of revealed, religion." Darwin was confident that, if any
such impressions were made by his theory, they would prove but
transient, and that ultimately men would come 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 it required the fresh act of creation to supply the
voids caused by the action of His laws.
IV.
It was, as we have said, in 1868 that Darwin published the two volumes
collectively entitled "Variation of Animals and Plants under
Domestication." It is the second and largely corrected edition brought
out in 1875 which we have under our eye. It is the outcome of the views
maintained by the author in this work and elsewhere that not only the
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 the whole
vast amount of difference between these forms has primarily arisen from
simple variability. Darwin recognized that he who for the first time
should consider the subject under this point of view would be struck
dumb with amazement. He submits, however, that the 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, whilst each which was in any way
injurious has been rigorously destroyed. 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 Darwin regards selection as the paramount power, whether applied
by man to the formation of domestic beings or by nature to the
production of species. Employing a favorite metaphor, he said: "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-form 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 critics of the Darwinian theory of the origin of species have
declared that natural selection explains nothing, unless the precise
cause of each slight individual difference be made clear. Darwin rejoins
that 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. This, in Darwin's opinion, 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 the hypothetical precipice may be called accidental, but the term is
not strictly applicable; 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.
In regard to the use, however, to which the fragments may be put, their
shape may be strictly said to be accidental. Here Darwin acknowledged
that we are brought face to face with a great difficulty in alluding to
which he felt that he was travelling beyond his 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 fan-tail 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?"
It is obvious, however, that 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 similar 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. Darwin, therefore, was unable to follow the distinguished
botanist, Prof. Asa Gray, in his belief that "variation has been led
along certain beneficial lines," like a stream "along definite and
useful lines of irrigation." Darwin's conclusion was that, 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 a natural selection or survival of the fittest, must
appear to us superfluous laws of nature.
V.
Next to the "Origin of Species," the volume which sets forth Darwin's
theory of the "Descent of Man" naturally excited the most widespread
attention. This book, which took the author three years to write, was
published in 1871, a second and carefully revised edition appearing
three years later. The data brought together occupy more than six
hundred pages. The conclusions reached may be summed up in a few
paragraphs. The principal induction from the evidence is that man is
descended from some less highly organized form. It was Darwin's
conviction that 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 cannot be disputed. Viewed in the
light of our knowledge of the whole organic world, their meaning is
unmistakable. The great principle of evolution stands out 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 pronounced 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 cannot any longer believe that man
is the product 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.
Darwin recognized that the high standard of our intellectual powers and
moral disposition constitutes the greatest difficulty which presents
itself after we have been driven by the mass of biological evidence to
accept his conclusion as to the origin of man. Touching this point, he
observes: "Every one who admits the principle of evolution must see that
the mental powers of the higher animals, which are the same in kind with
those of man, though so different in degree, are capable of advancement.
Thus the interval between the mental powers of one of the higher apes
and of a fish, or between those of an ant and scale-insect, is immense;
yet their development does not offer any special difficulty, for with
our domesticated animals the mental faculties are certainly variable,
and the variations are inherited. No one doubts that their mental
faculties are of the utmost importance to animals in a state of nature.
Therefore the conditions are favorable for their development through
natural selection. The same conclusion may be extended to man; the
intellect must have been all-important to him, even at a very remote
period, as enabling him to invent and use language, to make weapons,
tools, traps, etc., whereby, with the aid of his social habits, he long
ago became the most dominant of all living creatures."
It is further pointed out that a great stride in the development of
man's intellect must have followed as soon as the half-art and
half-instinct of language came into use; for the continued use of
language must have reacted on the brain, and produced an inherited
effect, and this again will have reacted on the improvement of language.
The largeness of the brain in man relatively to his body, compared with
the size of that organ in the lower animals, is attributable in chief
part to the early use of some simple form of language, that engine which
affixes signs to all sorts of objects and qualities, and excites trains
of thought which would never arise from the mere impression of the
senses, or, if they did arise, could not be followed out. The higher
intellectual powers of man, such as those of ratiocination, abstraction,
self-consciousness, etc., probably follow from the continued improvement
and exercise of the other mental faculties.
How man's moral qualities came to be developed is an interesting problem
which is considered by Darwin at some length. He holds that their
foundation lies in the social instincts under which term are included
family ties. These instincts are highly complex, and, in the case of the
lower animals, give special tendencies toward certain definite actions.
But the more important elements are love and the distinct emotion of
sympathy. Animals endowed with the social instincts take pleasure in one
another's company, warn one another of danger, defend and aid one
another in many ways. These instincts do not extend to all the
individuals of the species, but only to those of the same community. As,
however, they are highly beneficial to the species, they have in all
probability been acquired through natural selection. In Darwin's
judgment the moral nature of man has reached its present standard partly
through the advancement of his reasoning powers, and consequently, of a
just public opinion, but especially from his sympathies having been
rendered more tender and widely diffused through the effects of habit,
example, instruction, and reflection. It is pronounced not improbable
that, after long practice, virtuous tendencies may be inherited.
Let us look a little more closely at the matter, for the difficulty of
explaining morality forms one of the greatest obstacles to the
acceptance of the Darwinian account of the descent of man. What do we
mean by a moral being? Manifestly, a moral being is one who is capable
of reflecting on his past actions and their motives, and of approving of
some while he disapproves of others. Man is the one being who certainly
deserves this designation, though attempts have recently been made to
show that a rudimentary morality may be traced in some of the lower
animals. In the fourth chapter of the book before us, Darwin undertakes
to demonstrate that the moral sense follows,--first, from the enduring
and ever-present nature of the social instincts; secondly, from man's
appreciation of the approbation and disapprobation of his fellows; and,
thirdly, from the high activity of his mental faculties, with past
impressions extremely vivid; in these latter respects he differs from
the lower animals. Owing to this condition of mind, man cannot avoid
looking both backwards and forwards, and comparing past impressions.
Hence, after some temporary desire or passion has mastered his social
instincts, he reflects and compares the now weakened impression of such
past impulses with the ever-present social instincts; and he then feels
that sense of dissatisfaction which all unsatisfied instincts leave
behind them, and resolves to act differently for the future. This
dissatisfaction Darwin would identify with conscience. Any instinct
permanently stronger or more enduring than another gives rise to a
feeling which we express by saying that it _ought_ to be obeyed. Darwin
suggests that a pointer dog, if able to reflect on his past conduct,
would say to himself I _ought_ (as indeed we say of him) to have pointed
at that hare, and not have yielded to the passing temptation of
hunting it.