The narrowness, increased length and increased height of the Eskimo skull, without change in its size or other characteristics, may readily be understood as compensatory adaptations, the development of which was initiated and furthered by the development and mechanical effects of the muscles of mastication.
A similar conclusion has been reached in my former study on the central and Smith Sound Eskimo (1910). It has been approached or reached independently by other students of the Eskimo, notably Fürst and Hansen (1915) in their great work on the East Greenlanders. It is a conclusion of much biological importance for it involves not merely the development but also the eventual inheritance of new characters.
Former authors, it was seen, have advanced the theories of an American origin of the Eskimo. This could only mean that he developed from the American Indian. And such a development would imply physical and hereditary changes at least as great as those indicated in the preceding paragraphs, and in less time. A differentiation commenced well back in Asia, geographically and chronologically, and advancing, to its present limits, in America would seem the more probable.
An origin of the Eskimo in Europe, during the last glacial invasion, would not only push into the hazy far past the same changes as here dealt with, but it would at the same time fail to explain the physical differences within the Eskimo group, and deny any substantial changes in him during the long time of his migration toward the American northern coasts.
Figure 29.—Probable movements of people from northeastern Asia to Alaska and in Alaska. (A. Hrdlička)
Absolute proofs of the origin of the Eskimo, as of that of the various strains of the Indians, are hardly to be expected. Such origins are so gradual and insidious that they would escape detection even if watched for while occurring; they are noticed only after sufficient differences have developed and become established, which takes generations. The solving of racial origins must depend on sound scientific induction.
Such induction may not yet be fully possible in the case of the Eskimo. The evidence is not yet complete. But with the present and other most recent data there is enough on hand for substantial indications. The evidence shows that barring some irregularities, due possibly to later intrusions or refluxes, the farther east in the Eskimo territory the observer proceeds the more highly differentiated and divergent the Eskimo becomes, and there is a greater gap between him and his Indian neighbors, as well as other races. Proceeding from the east westward, conditions are reversed. In general the farther west we proceed the less exceptional on the whole the Eskimo becomes and the more he approximates the Indian, particularly the Indian of Alaska and the northwest coast. As this can not, in the light of present evidence, be attributed alone to mixture, it is plain that if it were possible to proceed a few steps farther in this direction the differences between the Eskimo and the Indian would fade out so that a distinction between the two would become difficult if not impossible.
The facts point, therefore, to an original identity of the source from which were derived the Indian, more particularly his latest branches, and the Eskimo, and to the identification of this source with the palaeo-Asiatic yellow-brown people of lower northern Asia. The differentiation of the Eskimo from this source must have proceeded over a fairly long time, and probably started already it would seem on the northern coasts of Asia, where conditions were present capable of beginning to shape him into an Eskimo; to be carried on since in the Bering Sea area and especially in the Seward Peninsula and farther northward and eastward. In a larger sense the cradle of the Eskimo, therefore, while starting probably in northeast Asia, covered in reality a much vaster region, extending from northern Asia and the Bering Sea to the far American Arctic.