‘Missing links’ in ancient Native American history

Two unrelated studies reveal unexpected details of the colonisation of the Earth’s northern polar region, including the existence of previously unknown group of people.

The studies, one using ancient teeth recovered from an archaeological site in Russia, and the other using genomes from people in northern Canada, both also add details to the deep history of Native American people from more southern regions.

In a paper published in the journal Nature, researchers led by Eske Willerslev from the University of Cambridge in the UK detail genetic evidence gleaned from the analysis of two 31,000-year-old human milk teeth found at a site near Russia’s Yana River.

DNA recovered from the teeth, which were located among a large trove of animal bones and ivory, indicate that they belonged to a previously unknown population that the researchers have dubbed Ancient North Siberians. 

The researchers suggest the Yana river site was home to around 40 of these people, with perhaps 500 more living in the broader area. They survived the harsh Siberian conditions by hunting woolly mammoths, rhinos and bison.

The genetic analysis also revealed a surprisingly close relationship to Native American people.

“These people were a significant part of human history, they diversified almost at the same time as the ancestors of modern-day Asians and Europeans and it’s likely that at one point they occupied large regions of the northern hemisphere,” says Willerslev. 

The researchers suggest that the Ancient North Siberians constitute a “missing link” between European populations and the first peoples of Canada and the US.

“We gained important insight into population isolation and admixture that took place during the depths of the Last Glacial Maximum – the coldest and harshest time of the Ice Age,” explains co-author David Meltzer, “and ultimately the ancestry of the peoples who would emerge from that time as the ancestors of the indigenous people of the Americas.”

Another significant piece of evidence regarding the advent of Native Americans emerges in another paper published in the same journal, written by a team headed by David Reich of Harvard Medical School and the Howard Hughes Medical Institute, both in the US.

Previous research has established that the first migratory human wave from the polar region down into the islands and mainland of North American occurred at some point earlier than 14,500 years ago. 

Around 5000 years ago, a second wave of people, known as the Paleo-Eskimos, followed in their footsteps. Then 800 years ago, the ancestors of modern Inuit and Yup’ik people arrived, obliterating all trace of the Paleo-Eskimos within a century.

The relationship between the vanished Paleo-Eskimos and modern-day indigenous inhabitants of the Canadian and US far north remains contentious, with some studies concluding that there was no gene flow from the older population into its replacement.

In the latest work, however, Reich and colleagues studied the genomes of 48 ancient and 93 modern individuals from Siberia, Alaska, the Aleutian Islands and Canada, and compared the results to already existing databases.

The exercise revealed a substantial Paleo-Eskimo genetic contribution to the inhabitants of the American Arctic, and to the Chukotkan region of north-eastern Russia. 

The gene flow also contributed to the heritage of Yup’ik, Inuit and Aleutian communities – and into speakers of two language groups, Athabaskan and Tlingit, who reside in parts of the lower 48 US states.

“”For the last seven years, there has been a debate about whether Paleo-Eskimos contributed genetically to people living in North America today,” says Reich. “Our study resolves this debate.”