When Christopher Columbus set foot in the Americas, he ended that separation of two continents that had been split apart for over 200 million years. Driven by the economic goal of establishing trade with China, he accidentally set off an ecological tumult as European vessels carried thousands of species and animals to new homes across the oceans. The Columbian Exchange as it is referred to -- underlies much of subsequent human history. Presenting the latest research by ecologists, anthropologists, archaeologists, and historians, Mann shows how the creation of this worldwide network of ecological and economic exchange fostered the rise of Europe, devastated imperial China, convulsed Africa, and for two centuries made Mexico City—where Asia, Europe, and the new frontier of the Americas dynamically interacted—the center of the world. In such encounters, he uncovers the genesis of today’s fiercest political disputes, from immigration to trade policy to culture wars.