Part 5

8. There is another reason for a belief in evolution furnished by geology, but of a somewhat different kind from that just stated. It consists in the fact that there are found in the rocks series or grades of structures, which fit with amazing accuracy on to the structures of existing species. Now, this is precisely what, according to the evolutional hypothesis, is to be expected. For, if evolution is true, existing species represent the tops of things. They are the existing and visible parts of processes which extend indefinitely back into the past, and whose deceased stages may reasonably be expected to be found fossil in the earth. Considering the youth and inexperience of paleontology and the torn and incoherent character of the record, it is surprising that anatomists have been able to accomplish what they have accomplished. In many cases—notably, those of man, the snail, the crocodile, and the horse—antecedent forms of structure have been found in almost unbroken gradations leading back to types differing immensely from their existing representatives. Bones and fossils of men have been found buried beneath the alluvium of rivers, under old lava-beds, and in caves, crusted over by the deposits of percolating waters. Many such fossils are found in quaternary rocks, along with the bones of animals still living and some extinct. Some of these remains indicate unmistakable affinities with the ape. The most celebrated of these discoveries is the fossil of an erect ape-man (_Pithecanthropus erectus_), found by a Dutch Governor on the island of Java in 1894. This fossil, in the shape and size of the head and in its general structure, strikes about as near as could be the middle between man and ape. That it is the fossil of an ambiguous form is indicated by the fact that, when it was examined by a company of twelve specialists at Berlin soon after its discovery, three of them declared it to be the remains of an individual belonging to a low variety of man; three others thought it was a large anthropoid; while the other six held that it was neither man nor anthropoid, but a genuine connecting link between them. It is discussed at length by Haeckel in ‘The Last Link,’ a paper read before the International Congress of Zoology, at Cambridge, in 1898. ‘It is,’ says the veteran biologist, ‘the much-sought “missing link” supposed to be wanting in the chain of primates which stretches unbroken from the lowest catarhine to the most highly developed man.’ Associated with this fossil ape-man were the fossils of the elephant, hyena, and hippopotamus, none of which any longer exist in that part of the world, also the fossil remains of two orders of animals now extinct. The genealogy of the crocodile has been traced by Huxley, through all intermediate stages, back to the giant reptiles of the early Tertiary.[5]And the pedigree of the horse has been even more completely worked out by the indefatigable Marsh. In the museum of Yale University may be seen the fossil history of this splendid ungulate, from the time it was a clumsy little quadruped only 14 inches high, and with four or five toes on each foot, down to existing horses. The earliest known ancestor of the horse, the eohippus, lived at the beginning of the Eocene epoch. It had five toes, almost equal, on each front foot (four toes behind), and was about the size of a fox. The orohippus, which lived a little later, had four toes on each front-foot, and three behind. The mesohippus, found in the Miocene, had three toes and one rudimentary toe on each front-foot, and three toes behind. It was about the size of a sheep. The miohippus, which is found later, had three toes on each of its four feet, with the middle toe on each foot larger than the other two. The pliohippus, living in the Pliocene epoch, had one principal toe on each foot, and two secondary toes, the two secondary toes not reaching to the ground. It was about the size of a donkey. Existing horses have one toe on each foot—the digit corresponding to the big middle finger—and the ruins of two others in the form of splints on the back of each ankle. In the embryo of the horse these splints are segmented, each of them, into three phalanges. Fossil remains representing all stages in the development of the horse have been found in the regions about the upper waters of the Missouri River.

It is an important fact that the types of structure forming any series grow more and more generalised as the distance from the present increases, and that different lines of development, when traced back into the past, often converge in types which combine the main characters of various existing groups. The horses, rhinoceroses, and tapirs, great as are the differences among them now, can be traced back step by step through fossil forms, their differences gradually becoming less marked, until ‘the lines ultimately blend together, if not in one common ancestor, at all events into forms so closely alike in all essentials that no reasonable doubt can be held as to their common origin.’ ‘The four chief orders of the higher mammals—the primates, ungulates, carnivora, and rodents—seem to be separated by profound gulfs, when we confine our attention to the representatives of to-day. But these gulfs are completely closed, and the sharp distinctions of the four orders are entirely lost, when we go back and compare their extinct predecessors of the Cenozoic period, who lived at least three million years ago. There we find the great sub-class of the placentals, which to-day comprises more than two thousand five hundred species, represented by only a small number of insignificant pro-placentals, in which the characters of the four divergent orders are so intermingled and toned down that we cannot in reason do other than consider them as the precursors of those features. The oldest primates, the oldest ungulates, the oldest carnivora, and the oldest rodents, all have the same skeletal structure and the same typical dentition (forty-four teeth) as these pro-placentals; all are characterised by the small and imperfect structure of the brain, especially of the cortex, its chief part, and all have short legs and five-toed, flat-soled (plantigrade) feet. In many cases among these oldest placentals it was at first very difficult to say whether they should be classed with the primates, ungulates, carnivora, or rodents, so very closely and confusedly do these four groups, which diverge so widely afterwards, approach each other at that time. Their common origin from a single ancestral group follows incontestably’.[6]

9. Man is the most powerful and influential of animals. He rules the world—rules it with a sovereignty more despotic and extensive than that hitherto exercised by any other animal. Many races of beings are, and have been for centuries, completely dominated by him. These races, during their long subjection, have been changed and transformed by man in a wonderful manner through his control of their power to breed. All domestic animals have come from wild animals; they have been derived by a process of selective evolution conducted by man himself. By continually choosing as the progenitors of each generation those with qualities best suited to his whims and purposes, man has evolved races as different from each other in appearance and structure, and as different from the original species, as many groups which, in the wild state, constitute distinct species; indeed, man has in some cases created entirely new species, both of plants and animals—species that breed true and are what biologists call ‘good’—by his own selections.

There are something over 150 different varieties of the domestic pigeon. Some of these varieties—as many as a dozen, Mr. Darwin thinks—differ from each other sufficiently to be reckoned, if they are considered solely with reference to their structures, as entirely distinct species. The carrier, for instance, the giant of the pigeons, measures 17 inches from bill-tip to the end of its tail, and has a beak 1 3/4 inches long. Around each eye is a large dahlia-like wattle, and another large wattle is on the beak, giving the beak the appearance of having been thrust through the kernel of a walnut. The tumbler is small, squatty, and almost beakless. It has the preposterous habit of rising high in the air and then tumbling heels over head. The roller, one of the many varieties of the tumbler, descends to the ground in a series of back somersaults, executed so rapidly that it looks like a falling ball. The runt is large, weighing sometimes as much as the carrier. The fantail has thirty or forty feathers in its tail, while all other varieties have only twelve or fourteen, the normal number for birds. The trumpeter, so named on account of its peculiar coo, has an umbrella-like hood of feathers covering its head and face, and its feet are so heavily feathered that they look like little wings. In the correct specimens of this variety the feathers have to be clipped from the face before the birds can see to feed themselves. The pouter has the absurd habit of inflating its gullet to a prodigious size, and the Jacobin wears a gigantic ruff. The homing pigeon has such a strong attachment for its cote that it will travel hundreds of miles, sometimes as many as 1,400 miles, in order to reach the home from which it has been separated. But it is not simply in their colour, size, habits, and plumage, that pigeons vary. There are corresponding differences in their structures, in the number of their ribs and vertebrae, in the shape and size of the skull, in the bones of the face, in the development of the breast-bone, and in the length of the neck, legs, and bill. Pigeons also differ in the shape and size of their eggs, and in their dispositions and voice. ‘There is,’ says Huxley in summing up his discussion of the great variety in these birds, ‘hardly a particular of either internal economy or external shape which has not by selective breeding been perpetuated and become the foundation of a new race’.[7]

All of the 150 different varieties of domestic pigeons have been evolved by human selection during the past three or four thousand years from the blue rock-doves which to-day inhabit the seacoast countries of Europe.

What is true of pigeons is also true largely of most of the other races associated with man—of cats, cattle, horses, sheep, swine, goats, fowls, and the like. All varieties of the domestic chicken—the clumsy Cochin with its feather-duster legs, the tall and stately Spanish, the great-crested Minorca, the Dorking with its matchless; comb and wattle, the almost combless Polish, the blue Andalusian, the gigantic Brahma, the tiny Bantam, the Wyandottes in all colours (black, white, buff, silver, and golden), the magnificent Plymouth Rocks, and the exceedingly pugnacious Game-cock—these and dozens of other varieties, all flightless, have come from the jungle-bird whose morning clarion still greets Aurora from the wilds of distant India. The dog is a civilised wolf, and the wild-boar is the progenitor of the oleaginous swine. The Merino and South Down breeds of sheep have come from the same stock in the last century and a half. In 1790 a lamb was born on the farm of Seth Wright in Massachusetts. It had a long body and short, bowed legs. It was noticed that this lamb could not follow the others over the fences. The owner thought it would be a good thing if all his sheep were like it. So he selected it to breed from. Some of its offspring were like it, and some were like the ordinary sheep. By continual selection of those with long bodies and short legs the ancon breed of sheep was finally produced. In 1770 in a herd of Paraguay cattle a hornless male calf appeared, and from this individual in a similar way came the stock of Muleys. The occasional appearance of horned calves and lambs among the offspring of hornless breeds of cattle and sheep are examples of atavism indicating the presence of a vestigial tendency to breed true to their horned ancestors. The Hereford cattle originated as a distinct variety about 1769 through the careful selections of a certain Englishman by the name of Tompkins. All domesticated quadrupeds, except the elephant, have come from wild species with erect ears, the ears acting as funnels to harvest the sound-waves. But there are few of them in which there is not one or more varieties with drooping ears—cats in China, horses in parts of Russia, sheep in Italy, cattle in India, and pigs, dogs, and rabbits in all long-civilised lands. We are so accustomed to seeing dogs and pigs with pendent ears that we are surprised to know there are varieties with erect ears. The goldfish is a carp, and in its native haunts in the waters of China it has the colour of the carp. The golden hue seen in the occupants of our aquaria has been given to this fish by the Chinese through the continual selection of certain kinds. The goldfish, almost as much as the pigeon, has been the sport of fanciers, and the strangest varieties have resulted. Some have outlandishly long fins, while others have no dorsal fin at all. Some are streaked and splotched with gold and scarlet; others are pure albinos. One of the most monstrous varieties has a three-lobed tail-fin, and its eyeballs, without sockets, are on the outside of its head. All of our common barnyard fowls—turkeys, ducks, geese, and chickens—are flightless, but the varieties from which the domesticated forms have come all have functional wings, two of these varieties crossing continents in their annual migrations.

Not only animals, but plants also, many of them, have been greatly changed by man in his efforts to adapt them to his uses as food, ornamentation, and the like. On the seaside cliffs of Chili and Peru may still be found growing the wild-potato—the small, tough, bitter ancestor of the mammoth Burbank, Peerless, Early Rose, and the nearly two hundred other varieties of this matchless tuber found in the gardens of civilised man. The cabbage, kale, cauliflower, and kohlrabi are all modifications of the same wild species (_Brassica oleracea_), the cauliflower being the developed flower, kohlrabi the stalk, and kale and cabbage the leaves. The peach and the almond, Darwin thinks, have also come from a common ancestral drupe, the peach being the developed fruit, and the almond the seed. There are nearly 900 different varieties of apples, varying in the most wonderful manner in size, colour, flavour, texture, and shape, but all of them probably derived from the little, sour, inedible Asiatic crab. The many times ‘double’ roses of our gardens have come from the five-petalled wild-rose of the prairies. The cultivated varieties of viburnum and hydrangea have showy corymbs of infertile flowers only, but the wild forms from which the domestic varieties have been derived have only a single marginal row of showy infertile flowers surrounding a mass of inconspicuous fertile flowers. It has been due to their efforts to please men that bananas, pineapples, and oranges have got into the habit of neglecting to produce seeds. There are certain species of grapes that are seedless, also seedless sugar-cane, and a seedless apple has just been announced by horticulturists. The development of domesticated plants is only in its infancy, and it is probably impossible even for the most agile imagination to dream of the miracles the horticulturist is destined to work in the ages to come. There is every reason to believe that seedless varieties of all our common fruits will ultimately be produced, and that in size, flavour, nutrient constituents, and appearance, they will be developed into forms utterly different from existing varieties. Just within the last few years the U.S. Department of Agriculture has developed a cotton-plant immune to the bacterial diseases of the soil, which had completely driven the cotton-raising industry out of large districts of the South. The cultivation of many of the cereals has gone on so long, and has proceeded so far, that their origin is lost in antiquity.

Whether or not it is possible for new varieties and species to be evolved is a question, therefore, which does not need to depend for reply wholly upon theory. It is known to have taken place; and the process by which the different varieties of domestic animals and plants have been evolved—domestic selection—is not different in principle from the process of natural selection, the chief operation by which life in general, both plant and animal, is assumed to have been evolved.

10. There are other reasons for a belief in organic evolution, but the last one I shall mention is the fact that the theory of organic evolution harmonises with the known tendencies of the universe as a whole. The organic kingdoms of the earth—animals and plants—are as truly parts of the terrestrial globe as the inorganic kingdom is; and as such they share in, and are actuated by, the same great tendency or instinct as that which actuates the whole. Nine-tenths of the substance of all animals and plants is oxygen, hydrogen, carbon, and nitrogen—the very elements which make up the entire ocean and air, and enter largely into the composition of the continents. The human body, which has essentially the same chemical composition as the bodies of animals in general, is made up of four solids, five gases, and seven metals—in all, sixteen elements of the something like seventy which constitute the entire planet. ‘In the past, man appeared to be a creature foreign to the earth, and placed upon it as a transitory inhabitant by some incomprehensible power. The more perfect insight of the present day sees man as a being whose development has taken place in accordance with the same laws as those that have governed the development of the earth and its entire organisation—a being not put upon the earth accidentally by an arbitrary act, but produced in harmony with the earth’s nature, and belonging to it as do the flowers and the fruits to the tree which bears them.’ Animals are not outside of, nor distinct from, the universe, as one might suspect who has listened much to the recital of tradition so long accepted as science. They are more or less detached portions of the planet earth which move over its surfaces and through its fluids and multiply, but which in their phenomena obey the same laws of chemistry and physics as those in accordance with which the rest of the universe acts. Animals are moulds through which digressing matters from the soil, sea, and sky pass on rounds of eternal itineracy.

Now, the earth as a planet is in process of evolution. Not many things are more certain than this. The earth has come out of fire. It has _grown_ to be what it is. Its mountains, valleys, plains, seas, shores, islands, lakes, rivers, and continents—these were not always here. They have been evolved. Not only the earth, but the entire family of spheres of which the earth is a member—the solar system—are all evolving. Mr. Spencer never did anything more profound than when he demonstrated in his ‘Law and Cause of Progress’ the universal migration of things from a condition of homogeneity toward a condition of greater and greater heterogeneity. The whole universe, or as much of it as can be examined by terrestrial instruments, has probably evolved out of the same primordial matters. The organic part of the earth has evolved, therefore, and is destined to continue to evolve, because it is a part of a whole whose habit or ambition it is to evolve.

The evidence is overwhelming. The theory of organic evolution is sustained by a mass of facts not less authoritative and convincing than that which supports the Copernican theory of the worlds. Evolution is, in fact, a doctrine so apparent that it only needs to be honestly and intelligently looked into to be accepted unreservedly. It is, indeed, _more_ than a _doctrine_. It is a _known_ fact. It is a _necessary effect_ of the _conditions known to exist_ among the animals and plants of the earth. If beings _vary_ among themselves generation after generation, if only the _fittest_ of each generation _survive_ and if the survivors tend to _transmit_ to their offspring the qualities of their superiority (and the animals and plants of the earth are known to do continually all of these things), then it follows _with mathematical certainty_ that evolution is going on, and that it will continue to go on as long as these conditions continue. It is inevitable. It could not be otherwise. We would _know_ that evolution were going on among organisms where these conditions existed, even though we had never observed it.

The boldest and most enthusiastic opponents of evolution have always been those with the least information about it. But the evidence is accumulating so rapidly, and is being drawn up in such unanswerable array, that, if it is not already the case, it will not be many years before it will be an intellectual reproach for anyone to discredit, or to be known to have discredited, this splendid and inspiring revelation.

1. Darwin: _Descent of Man_, 2nd edit.; London, 1874. 2. Huxley: _Man’s Place in Nature_; New York, 1883. 3. Thompson: _Outlines of Zoology_, 3rd edit.; Edinburgh, 1899. 4. Drummond: _Ascent of Man_; New York, 1894. 5. See table of geological ages, at the end of the chapter. 6. Haeckel: _The Riddle of the Universe_; New York, 1901. 7. Huxley: _On the Origin of Species_, lecture iv.

X. The Genealogy of Animals.

Life originated in the sea, and for an immense period of time after it commenced it was confined to the place of its origin. The civilisations of the earth were for many millions of years exclusively aquatic. It has, indeed, been estimated that the time required by the life process in getting out of the water—that is, that the time consumed in elaborating the first species of land animals—was much longer than the time which has elapsed since then. I presume that during a large part of this early period it would have seemed to one living at that time extremely doubtful whether there would ever be on the earth any other kinds of life than the aquatic. And if those who to-day weave the fashionable fabrics of human philosophy, and who know nothing about anything outside the thin edge of the present, had been back there, they would no doubt have declared confidently, as they looked upon the naked continents and the uninhabited air and the sea teeming with its peculiar faunas, that life upon solids or in gases, life anywhere, in fact, except in the sea, where it had always existed, and to which alone it was adapted, was absolutely, and would be forever, impossible; and that feathered fishes and fishes with the power to run and skip, and especially ‘sharks’ competent to walk on one end and jabber with the other, were unthinkable nonsense. Life originated in the sea for the same reason that the first of the series of so-called ‘civilisations’ which have appeared in human history sprang from the alluvium of the Euphrates and the Nile, because the conditions for bringing life into existence were here the most favourable. The atmosphere was incompetent to perform such a task as the inventing of _protoplasm_ and there was no land above the oceans.