Department of Anthropology and Institute for Genomic Biology, University of Illinois at Champaign-Urbana
Friday Morning, 200ABC
From the 15th to 19th Centuries, Native American populations suffered staggering losses due in part to pathogens stemming from European colonization. Chief among these was smallpox, tuberculosis, and measles, which decimated entire nations according to historical documents. During this same period, colonizing European populations suffered far fewer losses with respect to these same diseases. To explain this discrepancy, prevailing hypotheses suggest that European contact altered Native American population density, diet, and genetic diversity, which may have increased their susceptibility to European-borne endemic disease. However, most of this evidence is either indirect or based on genetic studies of living populations, making it difficult to examine to what extent genetics contributed to this presumed susceptibility.
Recent advances in ancient DNA techniques have allowed us to reconstruct the entire coding region (i.e., the exome) of ancient Native Americans for comparison with living individuals from the same geographic region. In this study, we examine relevant genetic differences in pre- and post-colonization populations. We hypothesize that adaptation to pathogens prevalent in the Americas and/or the absence of endemic European-borne pathogens may have altered specific immune related genes in ancient Native Americans. These changes may therefore serve to explain aspects of the historical experiences of Native peoples with European-borne pathogens. This work emphasizes the evolutionary consequences of an initial demographic separation followed by a dramatic merging of populations that had been separated for thousands of years. This work thus helps to illuminate the dynamics of adaptation to new environments in the context of demographic change.