Between 1500 and 1800, roughly two and a half million Europeans moved to the Americas; they carried twelve million Africans there by force; and as many as fifty million Native Americans died, chiefly of disease. Europe is spread over about four million square miles, the Americas over about twenty million square miles. For centuries, geography had constrained Europe’s demographic and economic growth; that era came to a close when Europeans claimed lands five times the size of Europe. Taking possession of the Americas gave Europeans a surplus of land; it ended famine and led to four centuries of