original home to America, we must inquire as to the geographical situation of that home. Judging by the climate which mankind now finds most favorable, the human race must have originated in the temperate regions of Europe, Asia, or North America. We are not entirely without evidence to guide to a choice of one of the three continents. There is a scarcity of indications of preglacial man in the New World and an abundance of such indications in the Old. To be sure, several skulls found in America have been supposed to belong to a time before the last glacial epoch. In every case, however, there has been something to throw doubt on the conclusion. For instance, some human bones found at Vero in Florida in 1915 seem to be very old. Certain circumstances, however, suggest that possibly they may not really belong to the layers of gravel in which they were discovered but may have been inserted at some later time. In the Old World, on the contrary, no one doubts that many human skulls and other parts of skeletons belong to the interglacial epoch preceding the last glacial epoch, while some appear to date from still more remote periods. Therefore no matter at what date man may have come to America, it seems clear that he existed in the Old World much earlier. This leaves us to choose between Europe and Asia. The evidence points to central Asia as man's original home, for the general movement of human migrations has been outward from that region and not inward. So, too, with the great families of mammals, as we know from fossil remains. From the earliest geological times the vast interior of Asia has been the great mother of the world, the source from which the most important families of living things have come.

Suppose, then, that we place in central Asia the primitive home of the thin-skinned, hairless human race with its adaptation to a highly variable climate with temperatures ranging from freezing to eighty degrees. Man could not stay there forever. He was bound to spread to 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.

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 few raised beaches indicate that during recent geological times the Aleutian Islands have been uplifted rather than depressed.

The passage from Asia to America at Bering Strait, on the other hand, is comparatively easy. The Strait itself is fifty-six miles wide, but in the middle there are two small islands so that the longest stretch of water is only about thirty-five miles. Moreover the Strait is usually full of ice, which frequently becomes a solid mass from shore to shore. Therefore it would be no strange thing if some primitive savages, in hunting for seals or polar bears, crossed the Strait, even though they had no boats. Today the people on both sides of the Strait belong to the American race. They still retain traditions of a time when their ancestors crossed this narrow strip of water. The Thilanottines have a legend that two giants once fought fiercely on the Arctic Ocean. One would have been defeated had not a man whom he had befriended cut the tendon of his adversary's leg. The wounded giant fell into Bering Strait and formed a bridge across which the reindeer entered America. Later came a strange woman bringing iron and copper. She repeated her visits until the natives insulted her, whereupon she went underground with her fire-made treasures and came back no more. Whatever may have been the circumstances that led the earliest families to cross from Asia to America, they little