The Atlantic Monthly/Volume 18/Number 108/The Darwinian Theory
THE DARWINIAN THEORY.
Great interest has been awakened, of late, by the promulgation of a new "Theory of Creation"; and non-scientific readers have met with numerous controversial articles in the journals, magazines, and newspapers of the day. The name of Darwin, after having been honorably known for a quarter of a century to the scientists of the world, has become familiar to us all as that of the author of this new theory. A word has been added to our vocabulary. "Darwinian" is now a distinctive epithet wherewith to individualize the new school of thought, and an appellation to designate its votaries. Notwithstanding the interest which Mr. Darwin's writings and the replies of his opponents have created, and the constant allusion to them in publications of all kinds; in spite of the active warfare they have incited; in spite of the sneers and sarcasms which have been launched by writers, lecturers, and preachers,—sure means of advertisement among the people,—few really and thoroughly comprehend Mr. Darwin's idea. A lecturer, alluding to it lately, says that it will be worthy of consideration when we see an ape turn into a man; and this is about the extent, we imagine, to which the great mass of people understand a theory which has been received as revelation by many of the first scientific men of the age,—men who have given their lives to patient, profound, untiring, unimpassioned study of nature, and who rank among the foremost thinkers of the world.
Leaving the argumentative detail to those whose learning is the only armory which can supply weapons adequate to the maintenance of the struggle, let us see if we cannot explain the idea which causes it; nor consider its verification to lie in the metamorphosis of an ape into a man.
Darwin's idea is generally conceived to be a new one. This is not strictly the case. The real foundation was laid long ago. It is the law of persistent force, acting on the universe. This is as old as Buddha, and was a dogma of Buddhism. It has been enunciated in some form or other for ages. But Darwin has infused into it a new vital strength, has given it new application, has clearly explained its workings, has been its prophet to the people. To fully understand the history and progress of the Darwinian theory, we must look back many years, and trace the influence which theology has had upon the advance of scientific knowledge.
For centuries the Bible was understood to contain a perfect, exact, undoubted account of the origin of the world. It was believed by everybody that the world was made in six days. The very imperfect acquaintance which the ancients had with geology and physics allowed them to accept this relation unchallenged. Faith was far stronger than reason; and, during the long ages in which the Church ruled supreme, this statement was accepted and implicitly believed by the whole race of Christians. But as men began to grow more enlightened,—as, one by one, the secrets of nature were revealed to the students whose desire for knowledge overbore their tacit acceptance of tradition,—doubts began to arise as to the possibility of the truth of this long-cherished idea. When the printing-press came, and enabled these ardent explorers to communicate freely the results of their studious labors, the leaven of discredit, thus disseminated, began to work in the mass, and the reason of men began to rise beneath the superincumbent theological pressure which had so long weighed upon it. The multitude of facts gathered together by these careful students became, by and by, so vast, and the conclusions to which they led so indubitable, that the theologians were forced, out of simple common-sense, to revise their expoundings of the sacred writings.
When it was found that the earth was made up of vast depositions of matter which contained the remains of long-extinct creatures, whose fragments were buried in solid rocks, once soft, oozy mud; when it was found that other rocks, hundreds of feet in thickness, were wholly composed of the imperishable remains of other extinct animals, which once lived and died and were gathered together in waters which broke over the very spot where these rocks now rise; when it was found that untold millions of years were necessary for the formation of one single group of these rocks, among many equally vast; when it was found that, in the memory of man, during the lapse of at least five thousand years, the earth had undergone no appreciable change; when it was found that the earth was the result of the action of laws existent in matter,—an upheaving, a washing away, a hardening, a disintegrating through a period of time beyond the conception of man,—the theologians were forced to substitute periods for days. When the old walls which had circumscribed man's mind became so crumbled as to allow of egress, individuals broke through them and revelled in the freedom of intelligent thought. When these walls were demolished by those who had themselves erected them, they were leaped, in all directions, by ardent explorers; and naturalists, no longer restrained by tradition, rushed upon voyages of discovery into the teeming world before them.
For a while this emancipation exhausted itself in the contemplation of the physical world, and an inquiry into brute life. Speculations and theories might riot in a past which was a practical eternity. They had unlimited space wherein to project, backward, the structure of the universe. But this long-stretching past was to be peopled only by the lower orders of animal life. The rocks were found to be filled with stony remains of animals who perished when the sandstone, which built old crumbling castles, was sea-shore mud; the chalk hills which bore them were found to be made up of myriads of little creatures. These humble representatives of life might be, must be, credited with a remote antiquity. But man was not an animal. He was a being apart. Although he was liable to heat and cold, disease and death, although his body was made of the same materials as the brute's, and was subject to the same laws of life, he was invested with an individuality which separated him from them. For a while the old influence of theological rule held even these venturous explorers to the ancient landmarks of human origin. By and by, the same impulse which had before led men to examine the proofs of physical creation induced them to consider the evidence of their own advent upon earth. Certain Scriptural statements did not appear reconcilable with each other. Cain went forth and builded a city; and there were artificers in brass and iron. Now Cain was only one of two men when he went forth. Whence came the citizens of that early settlement, and how did they understand the production of brass, a composite metal? How was it that man always met man wherever he went on the globe? Five thousand years ago the varied races were known to be distinct as now, and yet man was formerly said to be but about six thousand years old. Could one thousand years have produced the changes then evident, while five thousand succeeding years have scarce altered these different races? These and many other difficulties led thinkers to question whether man might not look much farther back into the past for his origin, and whether the same laws which had governed the birth, continuance, and distribution of other animals were not always in action to produce in him kindred results. The old belief, that all men descended from one man, began to be shaken; and good, honest, faithful Christians expressed their doubts of the matter. It was surmised that they were created in numbers. The old idea, that animals were all created in individual pairs, was found to be incompatible with the discovery of animal remains, in profusion, in rocks which were mud ages before any Adam could have existed to give them Hebrew names. Then, breaking away from the theological bonds, there sprang into active thought men of far-reaching minds, who began a thorough reconstruction of the whole theory of creation. The handwriting on the wall was Natural Law. All creation, man included, was but the result of one undeviating, unceasing, eternal, all-pervading law, and the state of the universe at any given moment was the state of evolution which that universe exhibited. Behind this law was the great inscrutable Spirit-power.
The infinite number of varied, aggregated facts stored up by man's patient study of this universe are irrelevant here, in a sketch of the progressive advance of his knowledge of creation. Those who desire to examine the evidence which has led to this verdict must go over the records themselves, or accept, out of their own convictions, the result of the examination. To entirely comprehend the Darwinian idea, one should be, to a certain extent, familiar with the principles of science. In other words, he should know more or less of what Darwin knows. He should be familiar with the general results of man's study in the different branches of science. He need not be an astronomer, a physicist, a geologist, a zoölogist, a botanist; but he should have a general acquaintance with the results of the labors of those who are such. He should, to a certain extent, understand the workings of Natural Law.
This is the great battle-ground on which the struggle is now taking place. The point at issue is, whether the physical changes of the material world, the introduction, continuance, and variation of organized beings, are due to the direct, special intervention of Deity, or whether they are the results of primeval laws, inherent in matter, and out of whose workings spring the phenomena of nature. The adherents to the former opinion maintain that the Deity has created all animals individually, or in individual species, by direct action, apart from natural forces, and indeed by an interference therewith. The votaries of the latter deny special creation, and maintain that all animals are, like the rest of the universe, the results of forces acting through all time, producing, by their diverse changing influences, the variations which, as they have widened and strengthened, have resulted in the difference exhibited among animals. The first is the old traditional idea, having its foundation in belief, and drawing its support from the Scriptures. The last is the modern conviction, having its foundation in reason, and drawing its support from the study of nature. How are these differences among animate creatures—these wide contrasts of form, size, and habits—produced, if not by God's special creation? This is the question which Mr. Darwin and his school of thinkers are seeking to answer.
Some half a century ago, M. Lamarck, a French naturalist, propounded a theory which excited the derision of the whole world. He accounted for these variations by suggesting that, as any special want was felt by an animal, the body took on that structure which was required to relieve it. To give a broad illustration: if men needed to fly for the support of life, wings would gradually grow out from their shoulders. Ridiculous as this may be, it showed that thinkers were at that time endeavoring to account, on purely natural grounds, for what they considered natural, and not supernatural phenomena.
Some twenty years ago, a book made its appearance which startled the whole reading world, and caused as much dispute as Darwin has since done. This was "Vestiges of the Natural History of Creation." It was anonymous, and the author has never acknowledged it: to this day he is unknown. This book was learned and lucid. It was received with delight by those who were still looking for some explanation of animal origin on natural grounds; and was derided quite as much as Lamarck's work by the adherents to the old traditional belief. Scouted by the great majority of naturalists, who still clung with tenacity to the notions of their predecessors, stigmatized as atheistic and abominable by theologians, it was first read with eagerness, and then put aside; and though it went through many editions, it is now almost forgotten. But this book was the beginning of Darwinism. It says:—
"We have seen powerful evidence that the construction of this globe and its associates, and, inferentially, that of all the other globes in space, was the result, not of any immediate or personal exertion on the part of Deity, but of natural laws which are expressions of his will. What is to hinder our supposing that the organic creation is also the result of natural laws, which are in like manner an expression of his will?"
Referring to the Deity as the great motive-power of all the universe, the author says:—
"To a reasonable mind the Divine attributes must appear, not diminished or reduced in any way, by supposing a creation by law, but infinitely exalted. It is the narrowest of all views of the Deity, and characteristic of a humble class of intellects, to suppose him acting constantly in particular ways for particular occasions. It, for one thing, greatly detracts from his foresight,—the most undeniable of all the attributes of Omnipotence. It lowers him towards the level of our own humble intellects. Much more worthy of him it surely is to suppose that all things have been commissioned by him from the first, though neither is he absent from a particle of the current of natural affairs in one sense, seeing that the whole system is continually supported by his providence. . . . . When all is seen to be the result of law, the idea of an Almighty author becomes irresistible, for the creation of a law for an endless series of phenomena—an act of intelligence above all else we can conceive—could have no other imaginable source, and tells, moreover, as powerfully for a sustaining as for an originating power."
He sums up the hypothesis which he seeks to sustain thus:—
"I suggest, then, as an hypothesis already countenanced by much that is ascertained, and likely to be further sanctioned by much that remains to be known, that the first step was an advance, under favor of peculiar circumstances, from the simplest forms of being to the next more complicated, and this through the medium, of the ordinary process of generation."
"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 vertebræ 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."