Molecular analysis of an ancient Thule population at Nuvuk, Point Barrow, Alaska

OBJECTIVES: The North American archaeological record supports a Holocene origin of Arctic Indigenous peoples. Although the Paleo-Inuit were present for millennia, archaeological and genetic studies suggest that modern peoples descend from a second, more recent tradition known as the Neo-Inuit. Origins of the Neo-Inuit and their relations to the earlier and later Indigenous peoples are an area of active study. Here, we genetically analyze the maternal lineages present at Nuvuk, once the northernmost community in Alaska and located in a region identified as a possible origin point of the Neo-Inuit Thule. The cemetery at Nuvuk contains human remains representing a nearly one thousand year uninterrupted occupation from early Thule to post-contact Inupiat. MATERIALS AND METHODS: We selected 44 individuals from Nuvuk with calibrated dates between 981 AD and 1885 AD for molecular analysis. We amplified and sequenced the hypervariable segment I of the mitogenome. We compared the Nuvuk data with previously published sequences from 68 modern and ancient communities from across Asia and North America. Phylogeographic analyses suggest possible scenarios of Holocene Arctic and sub-Arctic population movements. RESULTS: We successfully retrieved sequence data from 39 individuals. Haplogroup frequencies in Nuvuk were typed as 66.7% A2b1, 25.6% A2a, and 7.7% D4b1a2a1a. These results suggest that the population at Nuvuk was closest to the ancient Thule and modern Inuit of Canada, and to the Siberian Naukan people. We confirm that haplogroups A2a, A2b1, D2a, and D4b1a2a1a appear at high frequency in Arctic and sub-Arctic populations of North America and Chukotka. Sister clades D2b and D4b1a2a1b are present in Asian and Eastern European populations. DISCUSSION: The ancient mitochondrial sequences from Nuvuk confirm the link between the North Slope and the Thule who later spread east, and the maternal discontinuity between the Neo-Inuit and Paleo-Inuit. We suggest haplogroups A2a, A2b, and D4b1a2a1a are linked to the ancestors of the Thule in eastern Beringia, whereas the D2 and D4b1a2a1 clades appear to have Asian Holocene origins. Further Siberian and Alaskan genomes are necessary to clarify these population migrations beyond a simple two-wave scenario of Neo-Inuit and Paleo-Inuit.