10,000 Years of Genetic Continuity in Northwest North America Revealed

“Mitochondrial DNA just traces the maternal line – your mother’s mother’s lineage – so, you’re missing information about all of these other ancestors,” said Lindo, the first author on the paper. “We wanted to analyze the nuclear genome so we could get a better assessment of the population history of this region.”

The team looked at genomic data from Shuká Káa (Tlingit for “Man Before Us”), an ancient individual whose remains – found in a cave in southeastern Alaska – date to about 10,300 years ago. They also analyzed the genomes of three more individuals from the nearby coast of British Columbia whose remains date to between 6,075 and 1,750 years ago.

“Interestingly, the mitochondrial type that Shuká Káa belonged to was also observed from another ancient skeleton dated to about 6,000 years ago,” Kemp said. “It seems to disappear after that. The nuclear DNA suggests that this is probably not about population replacement, but rather chance occurrence through time. If a female has no children or only sons, the mitochondrial DNA is not passed to the next generation. As a male, Shuká Káa could not have passed on his own mitochondrial DNA; he must have had some maternal relatives that did so.”

“DNA from the mitochondria and Y chromosome provide unique yet sometimes conflicting stories, but the nuclear genome provides a more comprehensive view of past events,” DeGiorgio said.

“The data suggest that there were multiple genetic lineages in the Americas from at least 10,300 years ago,” Malhi said.

The descendants of some of those lineages are still living in the same region today, and a few are co-authors on the new study. Their participation is the result of a long-term collaboration between the scientists and several native groups who are embracing genomic studies as a way to learn from their ancestors, said Worl, who is Tlingit, Ch’áak’ (Eagle) moiety of the Shangukeidí­ (Thunderbird) Clan from the Kawdliyaayi Hít (House Lowered From the Sun) in Klukwan, Alaska.

“We supported DNA testing of Shuká Káa because we believed science ultimately would agree with what our oral traditions have always said – that we have lived in southeast Alaska since time immemorial. The initial analysis showed the young man was native, and now further studies are showing that our ancestral lineage stems from the first initial peopling of the region,” said Worl, who also is an anthropologist. “Science is corroborating our oral histories.”

The National Science Foundation supported this research.