The Great Divide History and Human Nature in the Old World and the New

In 15,000 B.C. early humankind, who had evolved in Africa tens of thousands of years before and spread out to populate the Earth, arrived in Siberia, during the Ice Age. Because so much water was locked up at that time in the great ice sheets, several miles thick, the levels of the world's oceans were much lower than they are today and early humans were able to walk across the Bering Strait, then a land bridge, without getting their feet wet and enter the Americas.