How epidemics devastated the indigenous people of the Americas

Abstract

There is growing consensus around the idea that much of our understanding on the causality of genetic plus environmentally based diseases and other complex phenotypes including suscep-tibility and/or resistance to pathogens is to be deciphered by exploring the fine-scale study of human genetic variation. When extrapolating this idea to the native populations, the challenge is greater due to the remarkable genetic variation that scientists have found within several regions of the Americas. After Columbus ́ landing in the Americas, the populations of the American conti-nent experienced a precipitous decline. Even though the spread of pathogens of European origin across nonimmune Native American is suspected to be responsible for a great propor-tion of the post-contact mortality, the situation cannot be extrapolated straightforwardly to all the New World populations. In fact, the local genetic, environmental, and cultural particulari-ties of the contact need to be considered in order to achieve a more sophisticated picture. Here I present some recurrent patterns regarding how epidemics devastated the indigenous people of the Americas. Specifically, I will focus on pattern similarities among the population decline of the Chumash (California) and Fueguians (Patagonia). A statistical comparison indicates that decimation coincides with mission estab-lishment. The concomitant increase in number of baptisms is almost-synchronically followed by a 15%/year of increasing in mortality each year, indicating a strong effect of density changes as a trigger to epidemic disease impact. Furthermore, I will discuss genetic and non-genetic factors that potentially generated deviations from the expected patterns of mortality due to infectious diseases.