Facts and fancies in modern science / Studies of the relations of science to prevalent speculations and religious belief

by Sir John William Dawson

Restoration (by G. F. Matthew) of a Trilobite (Paradoxides) from the Lower Cambrian, as an evidence of the existence of crustacean animals of high type and great complexity in this early age. If such animals were evolved from Protozoa by slow and gradual changes, the time required would be greater than that which intervened between the Cambrian period and the present time.

This wonderful Palæozoic Age was, however, but a temporary state of the earth. It passed away, and was replaced by the Mesozoic, emphatically the reign of reptiles, when animals of that type attained to colossal magnitude, to variety of function and structure, to diversity of habitat in sea and on land, altogether unexampled in their degraded descendants of modern times. Sea-lizards of gigantic size swarmed everywhere in the waters. On land, huge quadrupeds, like Atlantosaurus and Iguanodon and Megalosaurus, greatly exceeded the elephants of later times; while winged reptiles—some of them of small size, others with wings twenty feet in expanse—flitted in the air. Strangely enough, with these reptilian lords appeared a few small and lowly mammals, forerunners of the coming age. Birds also make their appearance, and at the close of the period forests of broad-leaved trees altogether different from those of the Palæozoic Age, and resembling those of our modern woods, appear for the first time over great portions of the northern hemisphere.

The Cainozoic, or Tertiary, is the age of mammals and of man. In it the great reptilian tyrants of the Mesozoic disappear, and are replaced on land and sea by mammals or beasts of the same orders with those now living, though differing as to genera and species (see Fig. 5). So greatly, indeed, did mammalian life abound in this period that in the middle part of the Tertiary most of the leading groups were represented by more numerous species than at present; while many groups then existing have now no representatives. At the close of this great and wonderful procession of living beings comes man himself—the last and crowning triumph of creation; the head, thus far, of life on the earth.

I have merely glanced at the leading events of this wonderful history, because its details may be found in so many manuals and popular works on geology. But if we imagine this great chain of life extending over periods of enormous duration in comparison with the short span of human history, presenting to the naturalist hosts of strange forms which he could scarcely have imagined in his dreams, we may understand how exciting have been these discoveries crowded within the lives of two generations of geologists. Further, when we consider that the general course of this great development of life, beginning with Protozoa and ending with man, is from below upward—from the more simple to the more complex—and that there is of necessity, in this grand growth of life through the ages, a likeness or parallelism to the growth of the individual animal from its more simple to its more complex state, we can understand how naturalists should fancy that here they have been introduced to the workshop of Nature, and that they can discover how one creature may have been developed from another by spontaneous evolution.

Fig. 5.

Skeleton of the American Mastodon, illustrating the number and wide distribution of elephantine animals of the three genera Dinotherium, Mastodon, and Elephas in the later Tertiary Age. Gaudry, the most eminent modern authority on these animals, remarks that the facts at present known do not "permit us to indicate any relation of descent between the elephantine animals and those of other orders known to us at present."

Many naturalists like Darwin and Haeckel, as well as philosophers like Herbert Spencer, are quite carried away by this analogy, and appear unable to perceive that it is merely a general resemblance between processes altogether different in their nature, and therefore in their causes. The greater part, however, of the more experienced palæontologists, or students of fossils, have long ago seen that in the larger field of the earth's history there is very much that cannot be found in the narrower field of the development of the individual animal; and they have endeavored to reduce the succession of life to such general expressions as shall render it more comprehensible and may at length enable us to arrive at explanations of its complex phenomena. Of these general expressions or conclusions I may state a few here, as apposite to our present subject, and as showing how little of real support the facts of the earth's history give to the pseudo-gnosis of monistic evolution.

1. The chain of life in geological time presents a wonderful testimony to the reality of a beginning. Just as we know that any individual animal must have had its birth, its infancy, its maturity, and will reach an end of life, so we trace species and groups of species to their beginning, watch their culmination, and perhaps follow them to their extinction. It is true that there is a sense in which geology shows "no sign of a beginning, no prospect of an end;" but this is manifestly because it has reached only a little way back toward the beginning of the earth as a whole, and can see in its present state no indication of the time or manner of the end. But its revelation of the fact that nearly all the animals and plants of the present day had a very recent beginning in geological time, and its disclosure of the disappearance of one form of life after another as we go back in time, till we reach the comparatively few forms of life of the Lower Cambrian, and finally have to rest over the solitary grandeur of Eozoon, oblige it to say that nothing known to it is self-existent and eternal.

2. The geological record informs us that the general laws of nature have continued unchanged from the earliest periods to which it relates until the present day. This is the true "uniformitarianism" of geology which holds to the dominion of existing causes from the first. But it does not refuse to admit variations in the intensity of these causes from time to time, and cycles of activity and repose, like those that we see on a small scale in the seasons, the occurrence of storms, or the paroxysms of volcanoes. When we find that the eyes of the old trilobites have had lenses and tubes similar to those in the eyes of modern crustaceans, we have evidence of the persistence of the laws of light. When we see the structures of Palæozoic leaves identical with those of our modern forests, we know that the arrangements of the soil, the atmosphere, and the rain were the same at that ancient time as at present. Yet, with all this, we also find evidence that long-continued periods of physical quiescence were followed by great crumplings and foldings of the earth's crust, and we know that this also is consistent with the operation of law; for it often happens that causes long and quietly operating prepare for changes which may be regarded as sudden and cataclysmic.