6. No Plague in the Land? The Alleged American Absence of Old World Communicable Diseases
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6 No Plague in the Land? The Alleged Ameri­ can Absence of Old World Communicable Diseases Whilst my physicians by their love are grown Cosmographers, and I their map. —John Donne, 1635 As mentioned in the introduction, the lethal effects of Old World diseases introduced post-­1492 to the immunity-­ lacking native populations of the Americas were devastating.1 Beyond human demography, however, apparent presences and absences of certain specific infectious diseases in the two hemispheres raise relevant issues. Readers routinely encounter statements to the effect that the oceans precluded interhemispheric interactions and that, therefore, Native Ameri­ cans were isolated from and, accordingly, exceedingly susceptible to Old World pathogens.2 The aim of this chapter is to assess what the history of communicable diseases may really tell us about whether interhemispheric contacts could have occurred. A Pox upon Them: Microbial Diseases and a “Virgin-­ Soil” Hemisphere The Post-­ Columbian Demographic Collapse in the New World The Old World gave rise to a much greater number of serious microbial human diseases than did the New. This reflects the larger size of the Afroeurasian land mass as well as a much longer human history there plus earlier agricultural intensification , population densification, and urbanization. In addition, importantly , it reflects the close association in the East­ern Hemisphere between people and their several species of domestic and commensal animals and the presence , in the tropics, of closely related wild primates eaten as bushmeat, many important human diseases having begun as animal maladies and having transferred to humans, a process known as zoonosis. In the Bering Strait region of the Arctic, mainland Asia and America are only some 54 miles apart, and intercontinental human contact was continuous; nevertheless, this region acted as a “cold screen” that filtered out from largely overland entry into the Americas 58 / Chapter 6 many of the disease organisms of Eurasia that were adapted to less severe climates . In addition, insect and annelid (roundworm) vectors (nonhuman carriers ) for warmer-­ climate human microbial diseases were unable to pass through the Arctic, excepting those whose organisms and/or vectors lived continuously in the warm microclimates of their hosts’ bodies (see chapter 26). The pre-­ Columbian populations of the Americas have long been considered “virgin soil” with respect to most of the important East­ ern Hemisphere microbial pathogens. The Ameri­ can archaeodemographer Henry Dobyns, for instance , asserted that “Native Ameri­cans truly inhabited a pre-­Columbian earthly paradise free of the diseases evolved in the Old World.”3 It is certainly the case that when one of the early post-­ Columbian European contributions to the natives of the West Indies—communicable Old World diseases such as small­ pox, measles, and plague—arrived, almost none of the Indians possessed any noticeable inherent immunity to the majority of them, unlike people in Europe, who, after sickening to a lesser degree, more of­ ten than not recovered from many of these maladies, owing to a degree of intrinsic immunity. For generations, the populations of Europe had been exposed to typhoid fever, smallpox, chicken pox, mumps, and other, lesser, infectious diseases. In warmer areas of the Old World, the inhabitants had existed in the presence of vari­ ous tropical diseases. Accordingly, in zones of endemism (self-­ sustaining disease presence), the most susceptible individuals had been weeded out of the breeding pool over the centuries, and a certain, if incomplete, genetically inherited innate immunity obtained (varying greatly in degree according to the nature of the disease), causing symptoms to be relatively mild.4 However, as the Canadian geographer W. George Lovell put it, “Whoever watched as Columbus came ashore . . . witnessed the beginning of a conquest that would cause the greatest destruction of lives in history,” mainly from disease plus its effects on production and reproduction.5 By 1548, for instance, the nearly three-­ quarter million native Taíno inhabitants of 1492 Hispaniola had been reduced to some five hundred souls, followed by full extinction as a distinct population. As the post-­ Columbian occupation and colonization of the Americas continued, with immigration of both Europeans and Af­ ri­ can slaves, these introduced diseases had horrendous impact on aborigi­ nals everywhere in the hemisphere, who expired in droves. This sometimes-­ literal decimation (or worse)6 of­ ten spread well ahead of direct European contact, “sof­ tening up” the indigenes for easy subjugation and domination. It was disease far more than force of superior arms that allowed the hijacking of the hemisphere by the Spanish, Portuguese, French, and British. Disease Susceptibility and...