The Lost City of the Monkey God

by Douglas Preston

When humans first walked into the Americas over the Bering Land Bridge fifteen to twenty thousand years ago,* our species existed everywhere as small, wandering bands of hunter-gatherers. There were no cities, no towns, no farming or animal husbandry. We were spread out and moving all the time, only rarely encountering other groups. The low population densities prevented most potential diseases from gaining a foothold. People suffered from parasites and infections, but they did not get most of the diseases so familiar in recent human history—measles, chicken pox, colds, the flu, smallpox, tuberculosis, yellow fever, and bubonic plague, to name only a few. In the last ten thousand years, as human population densities increased, disease moved into center stage of human affairs. Pandemics changed the very arc of human history. Despite our dazzling technology, we are still very much at the mercy of pathogens, old and new. In his groundbreaking book Guns, Germs, and Steel, biologist Jared Diamond poses the question: Why did Old World diseases devastate the New World and not the other way around? Why did disease move in only one direction?* The answer lies in how the lives of Old World and New World people diverged after that cross-continental migration more than fifteen thousand years ago.