For the past 12,000 years, the earth has experienced a relatively stable climate. Today, that predictability has ended, and global warming is our new reality. Yet such shifting weather patterns threatened Homo sapiens once before, right here in North America as the continent was first being colonized. About 15,000 years ago, the weather began to warm, melting the glaciers of the Late Pleistocene and driving the beasts of the Ice Age toward extinction. In this new landscape, humans managed to adapt to unfamiliar habitats and dangerous creatures in the midst of a wildly fluctuating climate. Are there lessons for modern people lingering along this ancient trail?