The science of life : fully illustrated in tone and line and including many diagrams

BOOK 3

them, and only three representatives have

THE SCIENCE OF LIFE

CHAPTER 4

the earth’s surface was made by a Creator,

managed to survive, in three patches of one is forced to admit not merely that these

tropical freshwater. The camels can be traced back to the Eocene

(V A). Their remains are found at first only in North America. Thence,

during the Miocene and Pliocene (V CG and D), they spread across two newly-emerged landbridges both southwards into South America and westwards to Asia. The two emigrant stocks went their own evolutionary ways to what we see to-day, while in their original home the family was abruptly extinguished in Pleistocene times (V. E). Finally, the tapirs too, like the lung-fish, were once widely spread. They are known as_ fossils from various

facts are unintelligible and even meaningless, but that the assignment was often definitely unfortunate. But if we are Evolutionists, the chaos becomes order, the mob of facts becomes

. a marshalled army, held

together in complete consistency by that dominat-

ing idea. The perplexities and apparent paradoxes

). | of geographical

_-~ | distribution at-

H f tenuate and ome O True a vanish in the light ancestral & of two chief prin-

Camels

ciples of interpretation: the principle that connects isolation with divergence of type, and _ the principle of looking in the past for the explanation of the present. Both principles rest upon the concept

Cenozoic (V) beds of Evolution as in both North their basis. WithAmerica, Europe, and out that basis we should

Asia. Doubtless they early penetrated into India and Malaya, and invaded South America by the Miocene (VC) landbridge from the north. They have been reduced to their present distribution simply by extinction in the regions between. Discontinuous distribution; the predominance of different groups of animals in different continents; the existence of unique species on remote islands ; the total absence of many creatures from countries where they are able to thrive and multiply when — introduced—these and many other facts of distribution are concordant.

If the assignment of different kinds and groups of animals to different regions of

244

Fig. 149. The present distribution of the Camel family explained by their past.

Remains of ancestral camels of Miocene Age (VG) and earlier are found in North America. In the Pliocene (V D) they are found also in the Old World. By the early Pleistocene (V E) the family is known from most of the world. Widespread extinction in the late Pleistocene left the Llama branch in South America, the true Camels in Central Asia and North Africa. (Outline of land-masses shown at the 100fathom line.)

have to relinquish all hopes of rationalizing animal and plant distribution, just as we should have to give up all hopes of rationalizing recapitulation, or vestigial organs, and to abandon the possibility of a science of comparative anatomy.

8 4 The Evidence Summarized

We have now passed in brief review a small fraction of each of the main kinds of evidence for Evolution. We have found that the rocks of earth’s crust make a book where our planetary history can be read, and that they contain fossil remains

which, when deciphered with the same care which an antiquary bestows upon his inscrip-