miércoles, 5 de abril de 2017

Ancient skeletons show direct link to modern tribes in the Pacific Northwest

This cast of a jaw comes from a 10,300-year-old ancient human who may have been an ancestor of modern tribes in the Pacific Northwest. Courtesy E. James Dixon
The Native Americans of the Pacific Northwest have always claimed to have deep roots in the region. Now, an ancient mariner may be able to back that claim up. Scientists sequencing the DNA of 10,300-year-old human remains from On Your Knees Cave in Alaska have found that he was closely related to three ancient skeletons found along the coast of British Columbia in Canada. These three ancient people were in turn closely related to the Tsimshian, Tlingit, Nisga’a, and Haida tribes living in the region today. The new finding reveals a direct line of descent to these tribes, and it shows—for the first time from ancient DNA—that at least two different groups of people were living in North America more than 10,000 years ago.

The study started 21 years ago with an unusually friendly collaboration between archaeologists and the Tlingit tribe that lived near the mariner’s remains on Prince of Wales Island in Alaska. Researchers gathered DNA from the 10,300-year-old skeleton known as Shuká Káa (“Man Ahead of Us”), initially focusing on maternally inherited mitochondrial DNA (mtDNA). They didn’t find a match between its mtDNA and members of the tribe, but they discovered his seafaring ways because isotopes from his teeth showed he ate a marine diet. The project ended on a note of good will between scientists and Native Americans, with a ceremonial reburial of the skeleton in 2008.

But as methods of sequencing ancient DNA got exponentially better, the team of geneticists requested permission from the Tlingit and Haida of Alaska, as well as tribes farther south in British Columbia, to extract nuclear DNA from Shuká Káa and three other ancient skeletons. They were allowed to sample the last remaining tissue from Shuká Káa’s molars and from the teeth of a 6075-year-old skeleton on Lucy Island in British Columbia (just 300 kilometers from On Your Knees Cave), a 2500-year-old skeleton from Prince Rupert harbor in British Columbia, and another 1750-year-old skeleton from the same area. [...] Science

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