According to a new analysis of nuclear DNA from ancient individuals, many of today’s indigenous peoples living in southern Alaska and coastal British Columbia are descendants of the first humans to make their home in northwest North America more than 10,000 years ago (early Holocene epoch).
A study by John Lindo et al reveals 10,000 years of genetic continuity in northwest North America. Image credit: Julie McMahon.
“Our analysis suggests that this is the same population living in this part of the world over time, so we have genetic continuity from 10,000 years ago to the present,” said lead co-author Ripan Malhi, a professor of anthropology at the University of Illinois at Urbana-Champaign.
“The findings also suggest that these early American peoples had a complex population history.”
This work comes on the heels of earlier studies of ancient Americans that focused on mitochondrial DNA, which occurs outside the nucleus of cells and is passed only from mothers to their offspring.
“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 first author Dr. John Lindo, a postdoctoral researcher at the University of Chicago.
“We wanted to analyze the nuclear genome so we could get a better assessment of the population history of this region.”
The researchers looked at genomic data from Shuká Káa (Tlingit for ‘Man Before Us’), an ancient individual whose remains — found the On Your Knees 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,” said lead co-author Brian M. Kemp, a professor of anthropology at the University of Oklahoma.
“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.”
The scientists turned their attention to nuclear DNA, which offers a more comprehensive record of a person’s ancestry.
“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,” said lead co-author Michael DeGiorgio, a professor of biology at Penn State University.
“The data suggest that there were multiple genetic lineages in the Americas from at least 10,300 years ago,” Prof. Malhi added.
“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,” said co-author Rosita Worl, the director of the Sealaska Heritage Institute in Juneau.
“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.”
“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 Tlingit, Ch’áak’ (Eagle) moiety of the Shangukeidí (Thunderbird) Clan from the Kawdliyaayi Hít (House Lowered From the Sun) in Klukwan, Alaska.
“Science is corroborating our oral histories.”
The research is published in the Proceedings of the National Academy of Sciences.
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John Lindo et al. Ancient individuals from the North American Northwest Coast reveal 10,000 years of regional genetic continuity. PNAS, published online April 4, 2017; doi: 10.1073/pnas.1620410114
This article is based on text provided by the University of Illinois at Urbana-Champaign.
