Part 7

Now, it cannot be held that the present races of animals differ from the ancient races merely by modifications produced by local circumstances and change of climate--for if species gradually changed, we must find traces of these gradual modifications, and between the palæotheria and the present species we should have discovered some intermediate formation; but to the present time none of these have appeared.

Why have not the bowels of the earth preserved the monuments of so remarkable a genealogy unless it be that the species of former ages were as constant as our own, or at least because the catastrophe that destroyed them had not left them time to give evidence of the changes?

Further, an examination of animals shows that though their superficial characteristics, such as colour and size, are changeable, yet their more radical characteristics do not change. Even the artificial breeding of domestic animals can produce only a limited degree of variation. The maximum variation known at the present time in the animal kingdom is seen in dogs, but in all the varieties the relations of the bones remain the same and the shape of the teeth undergoes no palpable change.

I know that some naturalists rely much on the thousands of ages which they can accumulate with a stroke of the pen; but there is nothing which proves that time will effect any more than climate and a state of domestication. I have endeavoured to collect the most ancient documents of the forms of animals. I have examined the engravings of animals including birds on the numerous columns brought from Egypt to Rome. M. Saint Hilaire collected all the mummies of animals he could obtain in Egypt--cats, ibises, birds of prey, dogs, monkeys, crocodiles, etc.--and we cannot find any more difference between them and those of the present day than between human mummies of that date and skeletons of the present day.

There is nothing, then, in known facts which can support the opinion that the new genera discovered among fossils--the palæotheria, anoplotheria, megalonyces, mastodontes, pterodactyli, ichthyosauri, etc.--could have been the sources of any animals now existing, which would differ only by the influence of time or climate.

As yet no human bones have been discovered in the regular layers of the surface of the earth, so that man probably did not exist in the countries where fossil bones are found at the epoch of the revolutions which buried these bones, for there cannot be assigned any reason why mankind should have escaped such overwhelming catastrophes, or why human remains should not be discovered. Man may have inhabited some confined tract of country which escaped the catastrophe, but his establishment in the countries where the fossil remains of land animals are found--that is to say, in the greatest part of Europe, Asia, and America--is necessarily posterior not only to the revolutions which covered these bones, but even to those which have laid open the strata which envelop them; whence it is clear that we can draw neither from the bones themselves nor from the rocks which cover them any argument in favour of the antiquity of the human species in these different countries. On the contrary, in closely examining what has taken place on the surface of the globe, since it was left dry for the last time, we clearly see that the last revolution, and consequently the establishment of present society, cannot be very ancient. An examination of the amount of alluvial matter deposited by rivers, of the progress of downs, and of other changes on the surface of the earth, informs us clearly that the present state of things did not commence at a very remote period.

The history of nations confirms the testimony of the fossils and of the rocks. The chronology of none of the nations of the West can be traced unbroken farther back than 3,000 years. The Pentateuch, the most ancient document the world possesses, and all subsequent writings allude to a universal deluge, and the Pentateuch and Vedas and Chou-king date this catastrophe as not more than 5,400 years before our time. Is it possible that mere chance gave a result so striking as to make the traditional origin of the Assyrian, Indian, and Chinese monarchies agree in being as remote as 4,000 or 5,000 years back? Would the ideas of nations with so little inter-communication, whose language, religion, and laws have nothing in common, agree on this point if they were not founded on truth? Even the American Indians have their Noah or Deucalion, like the Indians, Babylonians, and Greeks.

It may be said that the long existence of ancient nations is attested by their progress in astronomy. But this progress has been much exaggerated. But what would this astronomy prove even if it were more perfect? Have we calculated the progress which a science would make in the bosom of nations which had no other? If among the multitude of persons solely occupied with astronomy, even then, all that these people knew might have been discovered in a few centuries, when only 300 years intervened between Copernicus and Laplace.

Again, it has been pretended that the zodiacal figures on ancient temples give proof of a remote antiquity; but the question is very complicated, and there are as many opinions as writers, and certainly no conclusions against the newness of continents and nations can be based on such evidence. The zodiac itself has been considered a proof of antiquity, but the arguments brought forward are undoubtedly unsound.

Even if these various astronomical proofs were as certain as they are unconvincing, what conclusion could we draw against the great catastrophe so indisputably demonstrated? We should only have the right to conclude that astronomy was among the sciences preserved by those persons whom the catastrophe spared.

In conclusion, if there be anything determined in geology, it is that the surface of our globe has been subjected to a revolution within 5,000 years, and that this revolution buried the countries formerly inhabited by man and modern animals, and left the bottom of the former sea dry as a habitation for the few individuals it spared. Consequently, our present human societies have arisen since this catastrophe.

But the countries now inhabited had been inhabited before, as fossils show, by animals, if not by mankind, and had been overwhelmed by a previous deluge; and, indeed, judging by the different orders of animal fossils we find, they had perhaps undergone two or three irruptions of the sea.

CHARLES DARWIN

The Origin of Species

Charles Robert Darwin was born at Shrewsbury, England, Feb. 12, 1809, of a family distinguished on both sides. Abandoning medicine for natural history, he joined H.M.S. Beagle in 1831 on the five years' voyage, which he described in "The Voyage of the Beagle," and to which he refers in the introduction to his masterpiece. The "Origin of Species" containing, in the idea of natural selection, the distinctive contribution of Darwin to the theory of organic evolution, was published in November, 1859. In only one brief sentence did he there allude to man, but twelve years later he published the "Descent of Man," in which the principles of the earlier volume found their logical outcome. In other works Darwin added vastly to our knowledge of coral reefs, organic variation, earthworms, and the comparative expression of the emotions in man and animals. Darwin died in ignorance of the work upon variation done by his great contemporary, Gregor Mendel, whose work was rediscovered in 1900. "Mendelism" necessitates much modification of Darwin's work, which, however, remains the maker of the greatest epoch in the study of life and the most important contribution to that study ever made. Its immortal author died on April 19, 1882, and was buried in Westminster Abbey.

I.--Creation or Evolution?

When on board H.M.S. Beagle as naturalist, I was much struck with certain facts in the distribution of the organic beings inhabiting South America, and in the geographical relations of the present to the past inhabitants of that continent. These facts, as will be seen in the latter chapters of this volume, seemed to throw some light on the origin of species--that mystery of mysteries, as it has been called by one of our greatest philosophers. On my return home, in 1837, it occurred to me that something might perhaps be made out on this question by patiently accumulating and reflecting on all sorts of facts which could possibly have any bearing on it. After five years' work, I allowed myself to speculate on the subject, and drew up some short notes; these I enlarged in 1844 into a sketch of the conclusions which then seemed to me probable. From that period to the present day I have steadily pursued the same object. I hope that I may be excused for entering on these personal details, as I give them to show that I have not been hasty in coming to a decision.

In considering the origin of species, it is quite conceivable that a naturalist, reflecting on the mutual affinities of organic beings, on their embryological relations, their geographical distribution, geological succession, and other such facts, might come to the conclusion that species had not been independently created, but had descended, like varieties, from other species. Nevertheless, such a conclusion, even if well founded, would be unsatisfactory, until it could be shown how the innumerable species inhabiting this world have been modified so as to acquire that perfection of structure and co-adaptation which justly excites our admiration.

Naturalists continually refer to external conditions, such as climate, food, etc., as the only possible cause of variation. In one limited sense, as we shall hereafter see, this may be true; but it is preposterous to attribute to mere external conditions the structure, for instance, of the woodpecker, with its feet, tail, beak, and tongue, so admirably adapted to catch insects under the bark of trees. In the case of the mistletoe, which draws its nourishment from certain trees, which has seeds that must be transported by certain birds, and which has flowers with separate sexes absolutely requiring the agency of certain insects to bring pollen from one flower to the other, it is equally preposterous to account for the structure of the parasite, with its relations to several distinct organic beings, by the effects of external conditions, or of habit, or of the volition of the plant itself.

It is, therefore, of the highest importance to gain a clear insight into the means of modification and co-adaptation. At the beginning of my observations it seemed to me probable that a careful study of domesticated animals and of cultivated plants would offer the best chance of making out this obscure problem. Nor have I been disappointed; in this and in all other perplexing cases I have invariably found that our knowledge, imperfect though it be, of variation under domestication, afforded the best and safest clue. I may venture to express my conviction of the high value of such studies, although they have been very commonly neglected by naturalists.

Although much remains obscure, and will long remain obscure, I can entertain no doubt, after the most deliberate study and dispassionate judgment of which I am capable, that the view which most naturalists until recently entertained, and which I formerly entertained--namely, that each species has been independently created--is erroneous. I am fully convinced that species are not immutable, but that those belonging to what are called the same genera are lineal descendants of some other and generally extinct species, in the same manner as the acknowledged varieties of any one species are the descendants of that species. Furthermore, I am also convinced that Natural Selection has been the most important, but not the exclusive, means of modification.

II.--Variation and Selection

All living beings vary more or less from one another, and though variations which are not inherited are unimportant for us, the number and diversity of inheritable deviations of structure, both those of slight and those of considerable physiological importance, are endless.

No breeder doubts how strong is the tendency to inheritance; that like produces like is his fundamental belief. Doubts have been thrown on this principle only by theoretical writers. When any deviation of structure often appears, and we see it in the father and child, we cannot tell whether it may not be due to the same cause having acted on both; but when amongst individuals, apparently exposed to the same conditions, any very rare deviation, due to some extraordinary combination of circumstances, appears in the parent--say, once amongst several million individuals--and it re-appears in the child, the mere doctrine of chances almost compels us to attribute its reappearance to inheritance.

Everyone must have heard of cases of albinism, prickly skin, hairy bodies, etc., appearing in members of the same family. If strange and rare deviations of structure are really inherited, less strange and commoner deviations may be freely admitted to be inheritable. Perhaps the correct way of viewing the whole subject would be to look at the inheritance of every character whatever as the rule, and non-inheritance as the anomaly.

The laws governing inheritance are for the most part unknown. No one can say why the same peculiarity in different individuals of the same species, or in different species, is sometimes inherited and sometimes not so; why the child often reverts in certain characters to its grandfather or grandmother, or more remote ancestor; why a peculiarity is often transmitted from one sex to both sexes, or to one sex alone, more commonly but not exclusively to the like sex.

The fact of heredity being given, we have evidence derived from human practice as to the influence of selection. There are large numbers of domesticated races of animals and plants admirably suited in various ways to man's use or fancy--adapted to the environment of which his need and inclination are the most essential constituents. We cannot suppose that all the breeds were suddenly produced as perfect and as useful as we now see them; indeed, in many cases, we know that this has not been their history. The key is man's power of accumulative selection. Nature gives successive variations; man adds them up in certain directions useful to him. In this sense he may be said to have made for himself useful breeds.

The great power of this principle of selection is not hypothetical. It is certain that several of our eminent breeders have, even within a single lifetime, modified to a large extent their breeds of cattle and sheep. What English breeders have actually effected is proved by the enormous prices given for animals with a good pedigree; and these have been exported to almost every quarter of the world. The same principles are followed by horticulturists, and we see an astonishing improvement in many florists' flowers, when the flowers of the present day are compared with drawings made only twenty or thirty years ago.