Wonders of Animal Development
( Originally Published Early 1900's )
THE veneration of age sentiment which should, and I believe actually does, appeal to the American people when clearly presented to them even more strongly than the commercial sentiment, is roused in equal strength by an intelligent appreciation of the race longevity of the larger animals which our ancestors found here in profusion, and of which but a comparatively small number still survive. To the unthinking man a bison, a wapiti, a deer, a pronghorn antelope, is a matter of hide and meat; to the real nature lover, the true sportsman, the scientific student, each of these types is a subject of intense admiration. From the mechanical standpoint they represent an architecture more elaborate than that of Westminster Abbey, and a history beside which human history is as of yesterday.
These animals were not made in a day, nor in a thousand years, nor in a million years. As said the first Greek philosopher, Empedocles, who 560 B.C. adumbrated the "survival of the fittest" theory of Darwin, they are the result of ceaseless trials of nature. While the Sequoia was first emerging from the Carboniferous, or Coal Period, the reptile-like ancestors of these mammals, covered with scales and of egg-laying habits, were crawling about and giving not the most remote prophecy of their potential transformation through ten million years into the superb fauna of the northern hemisphere.
The descendants of these reptiles were transformed into mammals. If we had had the opportunity of studying the early mammals of the Rocky Mountain region with a full appreciation of the possibilities of evolution, we should have perceived that they were essentially of the same stock and ancestral to our modern types. There were little camels scarcely more than twelve inches high, little taller than cotton-tail rabbits and smaller than the jackass rabbits; horses fifteen inches high, scarcely larger than, and very similar in build to, the little English coursing hound known as the whippet; it is not improbable that we shall find the miniature deer; there certainly existed ancestral wolves and foxes of similarly small pro-portions. You have all read your Darwin carefully enough to know that neither camels, horses, nor deer would have evolved as they did except for the stimulus given to their limb and speed development by the contemporaneous evolution of their enemies in the dog family.
A million and a half years later these same animals had attained a very considerable size ; the western country had become transformed by the elevation of the plateaux into dry, grass-bearing uplands, where both horses and deer of peculiarly American types were grazing. We have recently secured some fresh light on the evolution of the American deer. Besides the Palaeomeryx, which may be related to the true American deer Odocoileus, we have found the complete skeleton of a small animal named Merycodus, nineteen inches high, possessed of a complete set of delicate antlers with the characteristic burr at the base indicating the annual shedding of the horn, and a general structure of skeleton which suggests our so-called pronghorn antelope, Antilocapra, rather than our true American deer, Odocoileus. This was in all probability a distinctively American type. Its remains have been found in eastern Colorado in the geological age known as Middle Miocene, which is estimated (sub rosā, like all our other geological estimates), at about a million and a half years of age. Our first thought as we study this small, strikingly graceful animal, is wonder that such a high degree of specialization and perfection was reached at so early a period; our second thought is the reverence for age sentiment.
The conditions of environment were different from what they were before or what they are now. These animals flourished during the period in which western America must have closely resembled the eastern and central portions of Africa at the present time.
This inference is drawn from the fact that the pre-dominant fauna of America in the Middle and Upper Miocene Age and in the Pliocene was closely analogous to the still extant fauna of Africa. It is true we had no real antelopes in this country, in fact none of the bovines, and no giraffes; but there was a camel which my col-league Matthew has surnamed the "giraffe camel," extraordinarily similar to the giraffe. There were no hippopotami, no hyraces. All these peculiarly African animals, of African origin, I believe, found their way into Europe at least as far as the Sivalik Hills of India, but never across the Bering Sea Isthmus. The only truly African animal which reached America, and which flourished here in an extraordinary manner, was the elephant, or rather the mastodon, if we speak of the elephant in its Miocene stage of evolution. However, the resemblance between America and Africa is abundantly demonstrated by the presence of great herds of horses, of rhinoceroses, both long and short limbed, of camels in great variety, including the giraffe-like type which was capable of browsing on the higher branches of trees, of small elephants, and of deer, which in adaptation to some-what arid conditions imitated the antelopes in general structure.
The Glacial Period eliminated half of this fauna, whereas the equatorial latitude of the fauna in Africa saved that fauna from the attack of the Glacial Period, which was so fatally destructive to the animals in the more northerly latitudes of America. The glaciers or at least the very low temperature of the period eliminated especially all the African aspects of our fauna. This destructive agency was almost as baneful and effective as the mythical Noah's flood. When it passed off, there survived comparatively few indigenous North American animals, but the country was repopulated from the entire northern hemisphere, so that the magnificent wild animals , which our ancestors found here were partly North American and partly Eurasiatic in origin.
Our animal fortune seemed to us so enormous that it never could be spent. Like a young rake coming into a very large inheritance, we attacked this noble fauna with characteristic American improvidence, and with a rapidity compared with which the Glacial advance was eternally slow; the East went first, and in fifty years we have brought about an elimination in the West which promises to be even more radical than that effected by the ice. We are now beginning to see the end of the North American fauna; and if we do not move promptly, it will became a matter of history and of museums.