Ancient DNA preserved in the icy climate of Siberia has revealed new insights into how ancient humans migrated five to seven millennia ago.
The discovery is important because it helps scientists fill a major gap in their knowledge of ancient humans. We know, for example, that humans began migrating out of Africa at least 50,000 years ago. But it took about 10,000 years ago before they started to develop agriculture. People living during the Hiatus – as well as much earlier 10 millennia ago in some places – had to forage for food. But they didn’t build many permanent structures, led a more nomadic lifestyle with a smaller population, so their remains are harder to find.
“This is a huge period of time when people came out of Africa before the development of agriculture,” says Cosimo Post, a professor at University of Tübingen.
IN study recently published in Current Biology, the researchers examined DNA from 10 different ancient people, which is quite a lot considering most of them are between 5,500 and 7,500 years old. These remains come from three places in Siberia – the Altai Mountains, the Kamchatka Peninsula and the Russian Far East.
“In Siberia, the preservation of DNA is amazing,” said Post, who co-authored the study. “This is fantastic for us because we don’t have to examine a lot of 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 studies.
Read more: Completing the human genome
Crossing over from America
Two men and a woman from Kamchatka lived relatively recently – only 500 years ago. The reason it’s interesting is that researchers haven’t published information on the ancient genome from this region until now. All three remains analyzed by Post and his colleagues contain small pieces of Native American ancestry.
The presence of these markers suggests that Native Americans were also crossing back into Russia before the time these individuals were alive. “This probably happened over a long period of time,” says Post.
While researchers previously knew that there was gene flow back and forth across the Bering Sea—perhaps for 5,000 years—this discovery extends that area of gene flow further south to the Kamchatka Peninsula.
Altai Encounters and Shamanism
Post and his colleagues were surprised to find a previously unknown population with mixed genetics in the Altai Mountains of southern Siberia.
At some point during the last ice age, a group of ancient northern Eurasians mixed with a population from northeastern Siberia. The mixture in question is one the researchers haven’t seen before, Post says. It is also unclear where these two groups first met and intermingled, as the people were mostly nomadic at the time. However, it is possible that they met in the area where the remains were found, which may have provided a good passage between the mountains to the north and the desert to the south.
“It’s an ideal meeting place for groups, geographically speaking,” says Post.
Five of the remains from the Altai Mountains – all male – had very similar DNA, although they date from different times between 7,500 and 5,500 years ago. But the sixth male, which dates back to about 6,500 years ago, came from further east. The DNA shows this, but so does the archaeological context. The individual was buried with rich grave goods and a costume that, according to Post, may indicate some type of shamanism.
Post 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 there was some movement between different people at that time.
Japanese connection
Finally, one of the analyzed individuals was found in the Russian Far East. This man is not that remarkable at first glance, as the DNA resembles that of other people of a similar age who have been analyzed before. Or at least three-quarters of the DNA is similar. The other quarter of this person’s genome appears to be Japanese.
This finding is surprising. This man dates back to about 7,000 years ago, but Japan was settled much earlier – probably 30,000 years ago. This means that people from Japan traveled back to the mainland and mixed with other people there.
“These hunter-gatherers were also able to cross bodies of water and interact with each other,” says Post.
Overall, these results show how mobile ancient humans were in Eurasia and even North America.
“These foraging communities were in close contact with each other, they were very mobile with each other, and they intermingled,” says Post. “We’re really talking about long-range mobility.”