Page:Popular Science Monthly Volume 73.djvu/510

506 Hamitic, the Greeks, who speak Aryan, and the Jews and Arabs, who spoke Semitic, is simply due to the fact that those peoples, from having long dwelt under practically similar conditions in the Mediterranean basin, have gradually acquired that physical similarity which has led Sergi to the assumption that they have a proximate common ancestry, and that they accordingly form but a single race.

Nor is there any lack of instances of convergence of type under similar conditions in the case of the lower animals. We saw that the asses of southwestern Asia approximate in color to the asses of northeast Africa, and in respect of the size of the ears and absence of shoulder stripe, more especially to the nearest of these, the ass of Somaliland. Yet it does not follow that they are more closely related to the Somali ass than they are to their own next neighbors, the kiang. On the contrary, it is much more likely that the Somali ass is closely related to those of Abyssinia, and that the southwestern Asiatic asses are closely related to the kiang. The approximation in color, absence of shoulder stripe and size of the ears between the asses of Somaliland and those of southwestern Asia must rather be explained by a convergence of types under the somewhat similar climatic conditions of Somaliland and the nearest parts of southwestern Asia. Again, though there are very strong, specific differences between the Grevy and Burchelline zebras met in the neighborhood of Lake Barringo, there is a curious approximation, not only in marking, but also in the teeth between these two species, which is best accounted for by supposing that it is the outcome of similar environment. It may be said that this approximation may be due to the interbreeding of the two species of zebras in the region where they overlap. This, in itself a most unlikely contingency from all that is known of the habits of wild species, certainly can not be alleged in the case of the convergence in type between the asses of southwestern Asia and the Somali ass, since they are separated by the Red Sea and the Persian Gulf.

Again, the representative of the crocodile family in the Ganges is distinguished by the extreme elongation of the head and jaws, whilst the same elongation of the head is equally characteristic of the representative of the dolphin family found in the same waters. Again, all through the Indian Ocean wherever any family of crabs have become inhabitants of coralline sands its members have long legs. Again, it has long been noticed that in Cutch all the larger animals have a tendency to become a sandy color, whilst in certain areas of South America insects, no matter to what family they belong, have a tendency to one common aspect.

It may, of course, be said that the changes in color of the horse family, tigers and insects are for "protective" reasons. But the case of the horse family alone is sufficient to dispose of this objection.