Virgin Soils Revisited

European arrival in the Americas was one of the most shocking demographic events of the last millennium. Indian populations declined by as much as 95 percent in the first century after the arrival of Christopher Columbus, prompting one historian to conclude that early America was a catastrophe-a horror story, not an epic.' This collapse established the foundation for the subsequent social and political developments of American history. Since the earliest encounters of colonization, colonists and their descendants have struggled to explain how and why depopulation occurred. They have debated the role of race, politics, and even genocide. All have concluded that infectious diseases, introduced by Europeans and Africans, played a decisive role. American Indians suffered terrible mortality from smallpox, measles, tuberculosis, and many other diseases. Their susceptibility led to American Indian decline even as European populations thrived. Discussions of the epidemiological vulnerability of American Indians rose to prominence with the work of William McNeill and Alfred W. Crosby in the 1970s. Both argued that the depopulation of the Americas was the inevitable result of contact between disease-experienced Old World populations and the virgin populations of the Americas. As Crosby defined them in 1976, Virgin soil epidemics are those in which the populations at risk have had no previous contact with the diseases that strike them and are therefore immunologically almost