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Genetics Unzipped Podcast: Genetics of the Americas: from migration to the modern day

In the latest episode of the Genetics Unzipped podcast, we’re looking at the genetic history of the Americas, including the controversies surrounding how humans first migrated to the continent and some of the modern day issues about how Native American genomes are used in genetic research. 

Presenter Dr Sally Le Page sits down with anthropologist, Professor Jennifer Raff, to chat about her new book, Origin: A Genetic History of the Americas, and then talks to geneticist Krystal Tsosie about how modern genetics is interested in Native American genomes and her work in co-founding an Indigenous-run biobank, Native BioData.

It wasn’t a bridge

The story of how humans first populated the Americas is still incomplete and ever changing, but anthropologist and geneticist Jennifer Raff dispels some common myths about this epic migration. 

“I invite people to think about it as a very dynamic, complex process done by populations much larger than you were led to believe in school,” she says.

Indeed, the image many of us have in our heads of a small tribe of humans perilously rushing from East Asia to North America over an icy bridge is likely to be far from reality. During the peak of the last Ice Age, sea levels dropped so much that what we now know as the Bering Strait was a large, ice-free area called Beringia. 

“It would have had a warmer and wetter climate thanks to the proximity of the ocean, with plants and animals living there. It wasn’t a bridge,” Raff argues, “it was a homeland.”

23,000 year-old footprints

Anthropologists haven’t even agreed upon when humans first reached the Americas, as what little evidence we have can be interpreted in multiple ways. Highly refined stone tools appear in the archaeological record about 13,000 years ago, which many thought marked the first peoples of the Americas. 

“But it turns out that over time, older and older archaeological sites start to be identified, and there’s huge controversies about all of them,” says Raff.

One such site is in White Sands National Park, USA. Anthropologists recently discovered striking footprints preserved in the mud, and by dating seeds embedded in the footprints, some estimate them to be 23,000 years old. 

“If these dates are correct,” Raff explains, “it means people must have reached North America before the ice sheets fused 25,000 years ago. It really makes for a whole new story.”

Science for whose interest?

The history of the first people of the Americas is also the story of the ancestors of today’s Native American populations. Krystal Tsosie is a Navajo geneticist who co-founded the Native BioBank consortium to protect the interests of Indigenous communities in genetic research.

Multinational pharmaceutical companies have taken a great deal of interest in Native American genomes as a potential source of information surrounding genetic health issues, but often with echoes of colonialism. 

“We are considered an ‘untapped, undiscovered resource’,” says Tsosie. “There’s a lot of interest in studying Navajo peoples because we’re ‘biologically pure’.” 

There are also big questions about who benefits from research into the genetics of these populations. For example, drug companies have historically used Indigenous people’s DNA to study Type 1 diabetes and search for new drug targets, even though this disease mainly affects people of European descent. 

“This is a perfect example of ‘science for whose interest?’,” explains Tsosie.

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Genetics Unzipped is the podcast from the UK Genetics Society, presented by award-winning science communicator Dr Kat Arney and produced by First Create the Media.  Follow Genetics Unzipped on Twitter @geneticsunzip, and the Genetics Society at @GenSocUK
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