"_That the simplest and most primitive type, under a law to
which that of like production is subordinate, gave birth to the
type next above it; that this again produced the next higher,
and so on to the very highest_, the stages of advance being in
all cases very small, namely, from one species to another; so
that the phenomenon has always been of a simple and modest
character."
In a Sequel which the author wrote, in answer to the numerous attacks
made upon him, he has the following:--
"The probable fact is, that the modification takes place in an
offshoot of the original tribe, which has removed into a
different set of circumstances, these circumstances being the
cause of the change; thus there is no need to presume that the
original tribe is at all affected by any such modification."
The author thus supposes that the variations among animals were
periodical and sudden, the results of some peculiar impetus given at
special periods. Later knowledge--the study of nature by the light of
greater experience--has exposed many errors in this work. Its crudities
have been made apparent; but the thought which pervaded it was
intrinsically right. The last passage quoted above foreshadows the more
elaborate speculations of the later philosopher.
In 1859 appeared Darwin's work, "On the Origin of Species, by Means of
Natural Selection, or the Preservation of Favored Races in the Struggle
for Life." Like its predecessors, it was a firebrand thrown into the
scientific camp. Like his predecessors, the author drew down obloquy and
anathemas from the clergy, sarcasm and vituperation from the laity, and
a host of replies from writers of all grades. Like his predecessor, the
author of the "Vestiges," he might have said, in the words of Agassiz:--
"The history of the sciences is present to tell us that there
are few of the great truths now recognized which have not been
treated as chimerical and blasphemous before they were
demonstrated."
Darwin, as he himself tells us in his Preface, spent twenty years in a
patient, laborious study of nature, having special reference to this
topic,--the origin of species. Certain observations made in the course
of his explorations in South America led him to the convictions which
subsequent study only strengthened; and, after having spent years in the
collection of facts bearing upon the subject, he gave his theory to the
world in the volume mentioned, which was merely a digest of the facts.
It is perhaps needless to say, that Charles Darwin is a naturalist of
the highest rank; that he stands among the foremost men of the day as a
clear-minded, trustworthy, accurate, profound thinker.
The Darwinian theory is erected on the primary foundation of a natural
law acting through all time,--a persistent force which is applied to all
creation, immutable, unceasing, eternal; which determined the
revolutions of the igneous vapor out of which worlds were first evolved;
which determines now the color and shape of a rose-bud, the fall of the
summer leaves, the course of a rippling brook, the sparkle of a diamond;
which gives light to the sun and beauty to a woman's eye. It rejects
utterly the idea of special creation, and maintains that the globe, as
it exists to-day with all its myriad inhabitants, is only one phase of
that primeval vapor which by the force of that law has reached its
present state. As a little microscopic egg becomes in time a full-grown,
living, breathing, loving animal by the operation of natural laws which
we term growth, so has the universe, with its denizens, become what it
is by the workings of Natural Law.
The precise process by which sentient existence first became evolved
from inorganic matter seems to be beyond the scrutiny of man. It is so
far without the scope of his experience, his speculation even, that it
is futile to attempt to surmise it; although certain interesting
phenomena have attended the experiments of naturalists, especially those
of Professor Jeffries Wyman. Darwin takes the subject up at the
appearance of animal life, and seeks to work out the causes of the
present variation among animals, and to detect the _modus operandi_ by
which the law of evolution has produced the multiform changes now
apparent. "Natural Selection" is his password into the great workshop of
Nature. The three great agencies at work there are the tendency of all
animals to transmit their peculiarities to their offspring, the tendency
of all animals to vary from their ancestors under varying influences
around them, and the constant changes taking place in their
surroundings. "Natural Selection" are the words chosen to express the
action of animals under these conflicting forces. The power of external
influence upon structure is exhibited in the remarkable results of man's
treatment of plants and animals. The varieties of pears and apples are
of his producing; and the different breeds of domestic animals are the
direct consequences of his influence. The most astonishing instance of
his power is shown in pigeons, which are made, by skilful breeders, to
assume a great variety of shapes, colors, and habits. To what is this
change due? If a rock-pigeon were left to itself, it would produce only
rock-pigeons, unless some new influences were brought to bear by natural
causes. Man gives a rock-pigeon some peculiar food, subjects it to some
peculiar treatment, and the creature begins at once to change; that is,
to accommodate itself to the new circumstances by which it is
surrounded. The plastic nature undergoes an alteration correspondent to
the new state of existence. In a few generations these varieties are
indefinitely multiplied; and then, by crossing these varieties, new ones
are again produced. What is then the state of affairs? We have a series
of birds which, were they discovered in new countries, would be
considered to be new species. They differ in shape and color, in the
number of their vertebrae and ribs, the number of wing and tail feathers,
the number of scales on their toes, and various other anatomical
peculiarities. Here then is proof that animals, when exposed to
influences different from those which surrounded their ancestors, take
on new forms and characteristics. This is man's work. But is not man one
of the many agents in the work of the Great Prime Mover? Let us suppose
that the peculiar circumstances which produced a pouter or a fan-tail
were to remain in force for centuries; would not pouters or fan-tails
continue to procreate, and thus a new species be added to the genus?
What, then, becomes of special creation of every species of animal, if
man in a few years can produce a dozen forms out of one, any one of
which dozen is so distinct as to be deemed a new species, were it
Nature's work and not man's? The fact is thus demonstrated that animals
become varied in accordance with variations in their surroundings. This
simple fact, once substantiated, is the key to the whole subject. Man's
influence ceases when he leaves the animal to itself. But Nature never
leaves the animal to itself. Her changes are slight and slow; but they
never go back. They are permanent, only to be reaffected as the
environment alters. When we consider the incalculable, inconceivable
lapse of time through which organic life has been swayed by the
never-ceasing action of the forces around it, we can imagine what a vast
variety of animal forms may have been evolved from some one primal
ancestor.
Darwin endeavors to explain, in detail, how this differentiation takes
place. The largest or strongest get the best food or the most attractive
females, and then transmit their strength or their peculiarities to
their progeny. These peculiarities are the results of the environment,
and if this shall go on changing in the direction of these
peculiarities, they will increase. Suppose that the climate should
gradually grow colder; the result might be a denser growth of hair.
Those which, by strength or otherwise, chanced to have denser hair than
others, would more readily endure the change, and would transmit the
habit to their young; others less fitted to endure the change would die
out. In a short time the young would be born with the dense hair, as it
is well known that any new habit assumed by animals is exhibited earlier
and earlier in the young, as long as it is a necessity of life. These
variations are never due to one single cause. Organized life is wrought
upon by a wonderfully complex web of influences. Darwin has the
following passage touching the action of vegetable and animal life upon
each other.
"In Staffordshire, on the estate of a relation where I had ample means
of investigation, there was a large and extremely barren heath, which
had never been touched by the hand of man; but several hundred acres of
exactly the same nature had been enclosed twenty-five years previously,
and planted with Scotch fir. The change in the native vegetation of the
planted part of the heath was most remarkable,--more than is generally
seen in passing from one quite different soil to another; not only the
proportional numbers of the heath plants were wholly changed, but twelve
species of plants (not counting grasses and carices) flourished in the
plantations, which could not be found on the heath. The effect on the
insects must have been still greater, for six insectivorous birds were
very common in the plantations which were not to be seen on the heath;
and the heath was frequented by two or three distinct insectivorous
birds. Here we see how potent has been the effect of the introduction of
a single tree, nothing whatever else having been done, with the
exception that the land had been enclosed, so that cattle could not
enter. But how important an element enclosure is, I plainly saw near
Farnham in Surrey. Here there are extensive heaths, with a few clumps of
old Scotch firs on the distant hill-tops; within the last ten years
large spaces have been enclosed, and self-sown firs are now springing up
in multitudes, so close together that all cannot live. When I
ascertained that these young trees had not been sown or planted, I was
so much surprised at their numbers that I went to several points of
view, whence I could examine hundreds of acres of the unenclosed heath,
and, literally, I could not see a single Scotch fir, except the old
planted clumps. But on looking closely between the stems of the heath, I
found multitudes of seedlings and little trees, which had been
perpetually browsed down by the cattle. In one square yard, at a point
some hundred yards distant from one of the old clumps, I counted
thirty-two little trees; and one of them, judging from the rings of
growth, had during twenty-six years tried to raise its head above the
stems of the heath, and had failed. No wonder that, as soon as the land
was enclosed, it became thickly clothed with vigorously growing young
firs. Yet the heath was so barren and so extensive that no one would
ever have imagined that cattle would have so closely and effectually
searched it for food.
"Here we see that cattle absolutely determine the existence of the
Scotch fir; but 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 birds. Hence
if certain insectivorous birds (whose numbers are probably regulated by
hawks or beasts of prey) were to increase in Paraguay, the flies would
decrease,--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 just have seen in Staffordshire, the insectivorous
birds, and so onwards in ever-increasing circles of complexity."
In the struggle for life, the strongest live; or, in other words, those
best fitted to live in the environment endure. Animals and plants
produce in vast excess of the possibility of life. A destruction of life
is going on to an almost incredible amount. Were this not the case, the
slowest breeders in existence would soon cover the earth so as to occupy
every inch of space. Darwin reckons that the elephant, the slowest
breeder, if allowed to go on unchecked, and to live his allotted term of
years, would in five centuries produce fifteen millions of elephants
from one pair. If every cod's egg had developed into a full-grown fish,
the whole ocean would, ages ago, have been packed with them, like
herrings in a box. In this destruction, the weaker animals and
plants--those least fitted to thrive under the influences around--become
the prey of others better fitted for the struggle, or die of their own
lack of assimilative force. Thus, through untold ages of shifting
outward circumstances, the plastic forms of organic life have been
remoulded. A little obscure plant, the food of an insect, dies out; the
insect itself, deprived of its food, dies out or migrates; the bird
which fed upon it dies out or migrates; the bird of prey follows the
like course. Migration introduces them to an entirely new state of
existence, temperature, food, and antagonists. The migrating animals are
replaced by others, which likewise experience new surroundings; and thus
the extirpation of a single plant may determine a long series of
changes. Instances of this kind are not uncommon. What must these
changes have been throughout the remote ages which have turned sea-shore
mud into uplifted mountain chains, and sunk long-stretching, sunny hills
into the ocean depths!
Darwin constructs his theory of gradual differentiation on the evidence
thus obtained. He takes a given specific animal form, and supposes that,
owing to some external change in a given locality, it takes on some
correspondent variation. But all of the individuals of the species may
not be likewise affected. The circumstances may alter in one place and
not in another. The result will be two varieties of animal. The variety
goes on increasing in diversity, while the original still continues to
produce its like. By and by the variety, having a greater tendency to
vary, from its having already done so, undergoes a new differentiation,
the difference being, in all cases, slight, and the time between the
periods of maximum change being hundreds, thousands of years. One of the
new varieties may by peculiar circumstances take on a special amplitude
of growth, while the other, peculiarly circumstanced, may be contracted
and dwarfed. One of the original varieties may by this time have
disappeared. The original itself may have disappeared. Thus the
connecting link between the two forms is lost. The more individualized
form may go on accenting its own peculiar characters, and again be
broken into new varieties, some of which may retain the old characters
in circumscribed areas, while others may increase in greater abundance
and occupy a much wider area. The wider the field of life, the more
numerous the differing influences and the more diverse the conditions
the animal must undergo. Thence arise more differentiations. After the
lapse of some millions of ages, these constantly forking growths will
have taken on a diversity to which that of the pouters and fan-tails is
trifling.
Some forms may be less plastic than others, and give way less readily to
the incident forces. These may remain unchanged for a far longer period
than subsequent varieties, and be coexistent with them. Some varieties
may take on a cerebral growth as widely different and as strongly
individualized as frame structure. Man himself is a striking instance.
The Negro, the Malay, the Mongolian, are almost precisely what they were
five thousand years ago. The Bushman, the Hottentot, the Patagonian, and
the Digger Indian are to-day not much above the animals about them;
while the Caucasian has gone on in a wonderful advancement, leaving the
other races in the same state of development in which they were when the
Caucasian was no farther advanced than they. And here is perhaps the
place to allude to the derisive objection to Darwinism, that it makes
man an improved monkey. Darwin's theory certainly gives to both some
vastly remote common ancestor; but it does not maintain the
metamorphosis of one into the other. It does not suppose that man was
once a gorilla. It supposes that from out of some of the
differentiations of some animal form arose the first man-like creature,
and that, gradually changing, like other animal forms, some of the
varieties eventually evolved into apes and orangoutangs, to stop there
and die out like hosts of other forms now extinct. But from some
strongly individualized variety sprang, with more rapid and advancing
growth, the primitive man, who has, under complex influences,
differentiated into the so-called races of mankind. We talk of man as
being something infinitely above all animals. There is a vast difference
between the highest and lowest species of the genus _homo_. Were the
race confined to those lowest species, we imagine that European and
American pride of nature would go before a grievous fall. These
constantly succeeding changes are supposed to have taken place during
the whole time that this earth has been fitted for animal life,--a
period of time so long that the human mind is unable to grasp it.
One objection to this theory, strongly insisted on, is the absence of
any evidence of connecting links between man and the lower animals, or
between the strongly defined demarcations of the animal orders. The
answer to this is, that little is known of the whole earth: much of it
is submerged now that was once above the waters and served for a
dwelling-place for organized beings. A great deal is known of the
sequence of forms which have been unearthed from their stony sepulchres.
The negative evidence is as weighty as the positive. Besides this,
millions of air-breathing animals die, without leaving anything behind
them to mark their existence. Preyed upon by other animals, devoured at
their death by myriads of insects, exposed to the action of destructive
chemical agents, they soon decay, and leave no trace behind. Who ever
finds the dead bodies of the thousands of animals and birds which perish
yearly? Who finds the remains of the familiar creatures which frequent
our woods and meadows? For one which is accidentally buried so as to
resist the destructive forces of air and water, millions are resolved
into their primitive elements, and are annihilated as structural forms.
And yet, because in portions of the vast deposits of rock the remains of
certain ancient forms are discovered, it is asked that the Darwinians
should furnish a perfect progressive sequence of fossils to elucidate
the theory, and prove it beyond dispute. Recent discoveries have brought
to light human remains in caves, where they are associated with bones of
extinct animals. That they are of very ancient origin is beyond
doubt,--older than any civilization, as we understand the term. But even
they are doubtless modern, when we take into consideration the time that
the earth has been as it now is. How many thousands of ages has it taken
the Niagara Falls to cut their way through the solid rock back from
Ontario to Erie? It is highly probable that the earth has been
approximately the same as it now is for many millions of years. Reaching
still farther back into the past, before this state of comparative
quiescence, can we not find adequate time for the gradual succession of
organized beings on this earth, and for the structural differentiations
which have finally resulted in the present position of things? Because
we see one day succeed another with no change in the organic life
around, because the written history of man records no vital change in
his structure, men deny the possibility of antecedent variation. Man's
written history is a thing of to-day. The builders of the Pyramids were
our brothers. The five thousand years which have elapsed since the
cultivated civilization of Egypt are but a day to the previous ages upon
ages of man's existence before that civilization was dreamed of. The
bones of untold myriads of human kind crumbled into dust before Egypt
saw the rudest mud-hut that foreshadowed the temples of her prime.
The imperfectness of the geological record is certainly a great
hindrance to the exact proof of the Darwinian theory, and is a strong
weapon in the hands of its opponents. But while so much of the dim,
remote past is attainable only by inference and deduction, the argument
is decisive for neither side. One weighty argument for the Darwinians is
the general plan upon which animals are constructed. All vertebrates
have the same typical form. Take off the skins from some dozen
air-breathing vertebrates, place the bodies in an upright attitude, and
they are in general structure identical. The position of the head, eyes,
and ears, the neck, the central vertebral column, the fore legs, which
are arms in that position, the pelvis, the hind legs, all bear a close
resemblance. Of course there are material differences; but they are
evidently moulded upon one general plan. If there were a special
creation for each species, why should they all necessarily have a
kindred structure? To be sure the question may be answered, that they
might as well be similar as dissimilar. But how much more in consonance
with the known action of natural laws is it, to suppose that from some
original type these various forms have gradually differentiated into
their present diversity of structure; the original typical plan, the
least variable characteristic, having maintained its individuality,
while the more plastic appendages have been swayed by incident forces.
This will logically and naturally account for the unlikeness, and yet
the resemblance.
The Darwinian theory then is, that Natural Law or Persistent Force,
acting through all time upon the universe, has evolved from certain
primitive organic forms of a very low order of existence the present
diversified races on the earth. It does not stop here. With the eye of
prescience it sees the process going on far into the ages yet to come.
What may be the result in that distant day, finite speculation may not
determine. But the laws which have swayed the world sway it still, and
will sway it forevermore. As in the past they have evolved order out of
disorder, heterogeneous beauty out of homogeneous crudity, progressive
individuality of being and thought out of chaotic vapor, so will they
continue their evolving force through all time, till the boasted
perfectness of this day of ours, perfect because it is our day, will be
as primitive to the later denizens of this globe as the barbarity of the
cave savages is to modern civilization.
A host of noble minds, each in its own peculiar province, is exploring
the vast field of knowledge. Darwin, Spencer, Huxley, Tyndal, Lyell,
Hooker, and many others, are giving their profound thought to the
elucidation of the laws which govern the vast universe of which they are
a part. Their intellects touch the scarce-seen planets; they turn over
the stony pages of earth's autobiography; they anatomize to their
ultimate atoms the structure of its organisms; they use the intelligence
evolved from their own growth to search for the law which has determined
that evolution. And they speak out their convictions manfully and
earnestly. They proclaim what is to them a revelation of truth in the
records which the past and the present offer to their understanding.
Herbert Spencer thus maintains the necessity of the expression of man's
deepest convictions, in a passage instinct with nobleness of thought and
dignity of utterance:--
"Whoever hesitates to utter that which he thinks the highest truth, lest
it should be too much in advance of the time, may reassure himself by
looking at his acts from an impersonal point of view. Let him duly
realize the fact, that opinion is the agency through which character
adapts external arrangements to itself,--that his opinion rightly forms
part of this agency,--is a unit of force, constituting, with other such
units, the general power which works out social changes,--and he will
perceive that he may properly give full utterance to his innermost
conviction, leaving it to produce what effect it may. It is not for
nothing that he has in him these sympathies with some principles and
repugnance to others. He, with all his capacities and aspirations and
beliefs, is not an accident, but a product of the time. He must remember
that, while he is a descendant of the past, he is a parent of the
future; and that his thoughts are as children born to him, which he may
not carelessly let die. He, like every other man, may properly consider
himself as one of the myriad agencies through whom works the Unknown
Cause; and when the Unknown Cause produces in him a certain belief, he
is thereby authorized to profess and act out that belief. For, to render
in their highest sense the words of the poet,
'Nature is made better by no mean,
But nature makes that mean: over that art
Which you say adds to nature, is an art
That nature makes.'
"Not as adventitious, therefore, will the wise man regard the faith
which is in him. The highest truth he sees he will fearlessly utter;
knowing that, let what may come of it, he is thus playing his right part
in the world,--knowing that, if he can effect the change he aims at,
well: if not, well also, though not _so_ well."