Anthropology, University of Pennsylvania
Friday 4:15-4:30, Grand Ballroom II
Today, as in the era of Hrdlicka, the key issues for understanding the prehistory of the Americas are the number of migrations that contributed to the diversity of Native American populations and the time at which the ancestral population(s) initially entered the New World. Recent studies of mtDNA and nuclear DNA variation in the Americas support the Beringian Incubation Model, in which the ancestral population entered the New World some 20,000-15,000 YBP after having genetically diverged from sister populations in Asia. However, other genetic and osteology studies suggest that two major population expansions gave rise to the biological diversity observed in the Americas. We have re-examined these key questions through high-resolution analysis of mtDNAs and Y-chromosomes from Siberia and North America. Phylogeographic analysis of whole mtDNA genome sequences from haplogroups A2, B4, C1, D1 and X2, and a similar analysis of Y-chromosome haplogroups Q1a3a* (M346), Q1a3a (M3) and C3 (M217), reveal distinct sets of maternal and paternal lineages in both Amerindian and circumarctic populations, with the latter reflecting population expansions occurring over the past 5,000-10,000 years. In addition, our analysis of Q1a3a* in Siberia and the Americas has allowed us to reshape the phylogeny of this branch, clarify genetic connections between populations from these two regions, and generate new coalescence estimates for derived branches in the Americas. These data have important implications for the timing and process of the colonization of South America, and, in particular, the type and number of founding haplogroups which first reached this region.
This work described in this paper was supported by the National Geographic Society, IBM, the Waitt Family Foundation, the National Science Foundation, SSHRC (Canada), and the Department of Anthropology at the University of Pennsylvania.