Native Americans experienced a strong population bottleneck coincident with European contact

Abstract

The genetic and demographic impact of European contact with Native Americans has remained unclear despite recent interest. Whereas archeological and historical records indicate that European contact resulted in widespread mortality from various sources, genetic studies have found little evidence of a recent contraction in Native American population size. In this study we use a large dataset including both ancient and contemporary mitochondrial DNA to construct a high-resolution portrait of the Holocene and late Pleistocene population size of indigenous Americans. Our reconstruction suggests that Native Americans suffered a significant, although transient, contraction in population size some 500 y before the present, during which female effective size was reduced by ∼50%. These results support analyses of historical records indicating that European colonization induced widespread mortality among indigenous Americans.Bayesian analysis | coalescent analysis | population genetics D espite considerable interest from both archaeologists and evolutionary geneticists, the demographic history of indigenous Americans remains contentious. One source of debate concerns the impact of European contact, where archaeological and genetic studies have painted contrasting stories. Both archaeological and historical records indicate that European contact and colonialism initiated a significant reduction in the indigenous population size through warfare, enslavement, societal disruption, and especially widespread epidemic disease (1-3), although the magnitude of population decline remains in dispute (4, 5). However, few genetic analyses have found evidence for a substantial population contraction during this period (but see refs. 6-8), and several recent, relatively large-scale demographic reconstructions have found no signal of a significant decline (9-12). Thus, genetic studies appear at odds with historical evidence, and the demographic impact of European colonization on indigenous Americans has remained unclear.Although historical evidence regarding population size during the 16th century is fragmentary, surviving personal and governmental accounts document substantial, if not catastrophic, declines during the period. For instance, working in Mexico, the Franciscan friar Fray Toribio de Benavente wrote that "At this time [Mexico] was extremely full of people, and when the smallpox began to attack the Indians it became so great a pestilence among them. . . that in most provinces more than half the population died." (13) Governmental taxation and tribute records have allowed for a more quantitative accounting in some areas. For instance, taxation records for 24 districts of Peru suggest that the taxable population size decreased by about 30% (from 466,748 to 324,895) between 1573 and 1602, although the region had previously endured two smallpox epidemics during 1546 and 1558 (3). Nonetheless, although historical records provide insights into demographic processes in specific regions, the overall extent of population decline remai...

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