Ancient DNA preserved in the icy climate of Siberia has revealed new insights about how ancient humans migrated five to seven millennia ago.
The finding is important because it helps scientists fill in a big gap in their knowledge about ancient humans. We know, for example, that humans began to migrate out of Africa at least 50,000 years ago. But it took until roughly 10,000 years ago before they began to develop farming. The humans living in the intermittent period — as well as much more recently than 10 millennia ago in some places — had to forage for their sustenance. But they didn’t build many permanent structures, living a more nomadic lifestyle with smaller populations, so their remains are harder to find.
“That is a huge timespan when humans came out of Africa before farming development,” says Cosimo Posth, a professor at the University of Tübingen.
In a study published recently in Current Biology, the researchers examined the DNA from 10 different ancient humans, which is quite a lot considering most of them date from 5,500 to 7,500 years old. These remains came from three locations in Siberia — the Altai Mountains, the Kamchatka Peninsula and the Russian Far East.
“In Siberia, the preservation of DNA is amazing,” says Posth, who co-authored the study. “This is fantastic for us because we don’t need to screen many remains to get usable DNA for genetic analysis.”
They modeled the genome from these remains and compared them to those of other individuals from previously published research.
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Passage from the Americas
Two males and one female from Kamchatka lived relatively recently — only 500 years ago. The reason it’s interesting is that researchers haven’t previously published any ancient genome information from this region. All three of the remains Posth and his colleagues analyzed contained small portions of ancestry from Indigenous Americans.
The presence of these markers suggests that Indigenous Americans were also crossing back to Russia prior to the period these individuals were alive. “This probably happened over a long period of time,” Posth says.
While researchers had previously known there was gene flow back and forth across the Bering Sea — perhaps for 5,000 years — this finding stretches that area of gene flow further south into the Kamchatka Peninsula.
Altai meetings and Shamanism
Posth and his colleagues were surprised to discover a previously unknown population with mixed genetics in the Altai Mountains in southern Siberia.
At some point during the last Ice Age, a group of ancient north Eurasians mixed with a population from northeastern Siberia. The corresponding mixture is one that researchers haven’t seen before, Posth says. It’s also not clear where these two groups first met and intermingled since the people were mostly nomadic at the time. It’s possible they met in the region where the remains are found, though, which may have provided a good passage between mountains to the north and the desert to the south.
“It’s a perfect meeting point for groups, geographically speaking,” Posth says.
Five of the Altai Mountains remains — all males — had very similar DNA, despite dating from different times between 7,500 and 5,500 years ago. But the sixth male, which dates to about 6,500 years ago, comes from farther east. The DNA shows this, but so does the archaeological context. The individual was buried with rich burial goods and a costume that Posth says could indicate some sort of shamanism.
Posth says it’s unclear whether this man is representative of a larger migration between the Altai Mountains and people farther east. But it shows that a degree of movement was occurring between different people at the time.
Finally, one of the analyzed individuals was found in the Russian Far East. This male isn’t that remarkable at first glance, for the DNA resembles that of other similarly aged people that have been previously analyzed. Or at least three-quarters of the DNA is similar. The other quarter of this man’s genome appears to be Japanese.
This discovery is surprising. This man dates back to about 7,000 years ago, but Japan was settled much earlier — possibly 30,000 years ago. This means that people from Japan were traveling back to the mainland and mixing with other humans there.
“These hunter-gatherers were also able to cross bodies of water and interact among each other,” Posth says.
Overall, these results show how fluid ancient people were in Eurasia and even North America.
“These foraging communities were in close contact with each other, they were highly mobile with each other and were admixing,” Posth says. “We are really talking about large-distance mobility.”
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