There is no reason to believe that the entry of man into America occurred as a single migration which was discontinued and never resumed. If one body of immigrants was able to find the way, it is almost certain that others would find it. The great speech diversification of America may have begun while the original speakers were still in the Old World.
It is practically certain that the peopling took place from Siberia via Bering Strait, other land bridges to America being geologically too ancient to have served man. Bering Strait is shallow, frozen over part of each year, less than so miles wide, with the Diomede islands near the middle. While probably never an insuperable obstacle even to primitive peoples, it never has been and is not now an easy means of communication; and the lands on both sides of it are inhospitable and capable of sustaining only a thin population. The Strait thus served much like a kinked tube. Man managed to filter through, and culture elements suc ceeded in being transmitted, but the flow of both was impeded.
There is no evidence that until the Russian occupation any advanced people ever occupied north-eastern Asia. Consequently, whatever relatively late accessions of inventions or other cultural materials reached the American Indians, were of a type normally occurring among peoples of a relatively low level. Both in America and Asia the higher attainments of civilization occur in latitudes not far from or below the Tropic of Cancer.
That the intercontinental connections occurred as just outlined, is strongly suggested by recent ethnic conditions about Bering Strait. The Eskimos on both sides of the strait are almost identical in physique, speech and customs; and farther back live Palaeo Asiatic tribes (Chukchee, Koryak, Yukaghir) and American tribes (Dene, Tlingit, Haida) which resemble each other so conspicu ously that some authorities have included the Palaeo-Asiatic ones with the Indians.
Race.—It follows that the racial origin of the American Indian has to be sought in Asia. The findings of anthropometry bear out the inference. The Indian belongs obviously to the Mongoloid division of the human species. He is brown skinned, with straight, stiff, black head hair, a minimum of beard and body hair, a definitely broad face (in popular parlance, high cheek bones), and moderate prognathism. These traits are constant among
Indians, as among East Asiatics. Minor peculiarities, such as shovel-shaped incisor teeth, and bluish pigment spots in the sacral region during infancy, occur equally among the two populations.
The relations of the American Indian are, however, to the Mongoloid stock as a whole rather than to any specific Mongolian people. They are probably closest to the East Siberians.
Although often called "red," the American Indians are so only when they paint themselves. Their general colour is a brown, little if any darker than that of the Japanese. The tallest people are found in the centre of the continent in the Mississippi valley, and for some distance north and east. Along the Pacific coast and in Mexico, body heights are less. The Aztecs and Mayas were short peoples. Head form is about as variable as in the Old World. In general, the cranial index is 79 or above (cephalic index 81+), except in six areas where it is less (longer heads): I, the Eskimos of the Arctic coast ; 3, 4, in the east, from Cape Hatteras to St. Lawrence river; from the St. Lawrence north of the Great Lakes almost to the Rockies; an irregular tract in the Ohio and middle Mississippi valleys; 5, 6, on or near the Pacific coast, two intermittent tracts or chains of separated groups, be tween northern California and the tip of Baja California ; from southern Arizona to central Mexico. In South America the long heads are almost all found in the eastern half of the continent, in or adjacent to Brazil.
The Eskimos (q.v.) are a well-marked sub-race. They are short, thick set, unusually long headed and broad faced, powerful jawed, narrow nosed, and with some tendency to the Mongolian eye. The remainder of the American race is difficult to sub-classify satisfactorily. HrdliCka distinguishes three types, of which he considers all existing populations in North and South America to be either representatives or mixtures. These are : 1, tall and broad headed (Athabascan) ; 2, long headed, mostly tall ; 3, broad headed, stature moderate to short. The more advanced peoples from Mexico to Peru are assigned to this third type.