科学美国人60秒:DNA Points to Multiple Migrations into the Americas

For more than ten thousand years, Alaska Native and Canadian First Nations people have lived along the Northwest coast of North America. Now, ancient remains have provided genetic proof of that long habitation.

“There’s largely the same gene pool in northern northwest North America today that there was ten thousand years ago.”

Ripan Malhi at the University of Illinois–Champaign. He and colleagues analyzed the DNA in four skeletons found in the region that range from 1,500 to 10,000 years old. And the results have two major implications. First, they support traditional oral histories about life in the region. Second, they open up the possibility for new theories about how people migrated to the continent—namely, more than one colonization.

“It could be that folks first moved south into Central and South America and then back up into North America, or it could be that there was another movement from northeast Asia later on in time. So, there are many different possibilities that could explain the patterns that we are seeing.”

The study is in the Proceedings of the National Academy of Sciences. [John Lindo et al., Ancient individuals from the North American Northwest Coast reveal 10,000 years of regional genetic continuity]

The researchers also compared genetic data from Northwest coast populations with DNA in remains unearthed south of the Canadian border. The analysis shows that the almost 13,000 year old Anzick Child found in Montana is related more closely to people from Central and South America than to Washington state’s 9,000-year-old Kennewick Man, who is of entirely different lineage. He is not related to people of the Northwest Coast, and his genes aren’t all that closely linked to Anzick Child’s South American relatives either. Which shows that the story of the settlement of the Western Hemisphere is still very much a work in progress.

—Emily Schwing