Red Mans Continent, The | Page 7

new regions, partly because of his innate migratory tendency and partly because of Nature's stern urgency. Geologists are rapidly becoming convinced that the mammals spread from their central Asian point of origin largely because of great variations in climate.* Such variations have taken place on an enormous scale during geological times. They seem, indeed, to be one of the most important factors in evolution. Since early man lived through the successive epochs of the glacial period, he must have been subject to the urgency of vast climatic changes. During the half million years more or less of his existence, cold, stormy, glacial epochs lasting tens of thousands of years have again and again been succeeded by warm, dry, interglacial epochs of equal duration.
* W. D. Matthew. "Climate and Evolution," N. Y. Acad. Sci., 1915.
During the glacial epochs the interior of Asia was well watered and full of game which supplied the primitive human hunters. With the advent of each interglacial epoch the rains diminished, grass and trees disappeared, and the desert spread over enormous tracts. Both men and animals must have been driven to sore straits for lack of food. Migration to better regions was the only recourse. Thus for hundreds of thousands of years there appears to have been a constantly recurring outward push from the center of the world's greatest land mass. That push, with the consequent overcrowding of other regions, seems to have been one of the chief forces impelling people to migrate and cover the earth.
Among the primitive men who were pushed outward from the Asian deserts during a period of aridity, one group migrated northeastward toward the Kamchatkan corner of Asia. Whether they reached Bering Sea and the Kamchatkan shore before the next epoch of glaciation we do not know. Doubtless they moved slowly, perhaps averaging only a few score or a hundred miles per generation, for that is generally the way with migrations of primitive people advancing into unoccupied territory. Yet sometimes they may have moved with comparative rapidity. I have seen a tribe of herdsmen in central Asia abandon its ancestral home and start on a zigzag march of a thousand miles because of a great drought. The grass was so scanty that there was not enough to support the animals. The tribe left a trail of blood, for wherever it moved it infringed upon the rights of others and so with conflict was driven onward. In some such way the primitive wanderers were kept in movement until at last they reached the bleak shores of the North Pacific. Even there something--perhaps sheer curiosity--still urged them on. The green island across the bay may have been so enticing that at last a raft of logs was knotted together with stout withes. Perhaps at first the men paddled themselves across alone, but the hunting and fishing proved so good that at length they took the women and children with them, and so advanced another step along the route toward America. At other times distress, strife, or the search for game may have led the primitive nomads on and on along the coast until a day came when the Asian home was left and the New World was entered. The route by which primitive man entered America is important because it determined the surroundings among which the first Americans lived for many generations. It has sometimes been thought that the red men came to America by way of the Kurile Islands, Kamchatka, and the Aleutian Islands. If this was their route, they avoided a migration of two or three thousand miles through one of the coldest and most inhospitable of regions. This, however, is far from probable. The distance from Kamchatka to the first of the Aleutian Islands is over one hundred miles. As the island is not in sight from the mainland, there is little chance that a band of savages, including women, would deliberately sail thither. There is equally little probability that they walked to the island on the ice, for the sea is never frozen across the whole width. Nevertheless the climate may at that time have been colder than now. There is also a chance that a party of savages may have been blown across to the island in a storm. Suppose that they succeeded in reaching Bering Island, as the most Asiatic of the Aleutians is called, the next step to Copper Island would be easy. Then, however, there comes a stretch of more than two hundred miles. The chances that a family would ever cross this waste of ocean are much smaller than in the first case. Still another possibility remains. Was there once a bridge of land from Asia to America in this region? There is no evidence of such a link between the two continents, for a