Ancient Genomes Shed Light on Early Human Migration in North Asia

A new study has shed light on the genetic makeup of ancient populations in North Asia, finding evidence of population movement from North America into North Asia by studying the ancient genomes of individuals from as many as 7,500 years ago. The study is published in Current Biology.

The genetic history of North Asia

North Asia covers an area of land from the west to the northeast of Siberia, which was once connected to North America through an ancient land bridge called Beringia. Genetic evidence suggests ancient populations made the migration from North Asia into North America, with most Native Americans descending from a single ancestral group called the “First Americans”. However, the genetic makeup of populations resident in North Asia around this time remains poorly studied, as despite the importance of this region as a corridor for migrations, analysis of ancient genomes found in this area is lacking.

Dr. Cosimo Posth, junior professor of archaeo- and paleogenetics at the University of Tübingen and senior author of the study, explained how the analysis of ancient genomes can provide important insights on our history: “By looking at the DNA of individuals living hundreds or thousands of years before today we can monitor how populations changed genetically in one location through time. We call this a ‘genetic time transect’, and when we compare this to surrounding populations it provides an extremely powerful tool to understand past population movements and interactions,” he said.

With the aim to fill the gaps in our understanding of ancient populations inhabiting this key migration corridor, Posth and colleagues analyzed genomes from ten ancient individuals found in North Asia that are up to 7,500 years old.

Uncovering ancient migrations

The researchers analyzed skeletal material from various archeological sites in the Altai (a region near the intersection of Russia, China, Mongolia and Kazakhstan) and the Russian Far East, including the Kamchatka Peninsula on the western side of the Bering Sea.

“Once we started analyzing the new genomes alongside previously published individuals’, we realized that geographically distant hunter–gatherer groups showed evidence of genetic connections to a much larger extent than previously expected,” Posth adds. “That is when we decided to combine all individuals into one study focusing on migration and admixture in ancient foraging societies across the vast area of North Asia.”

Using these genetic clues, the researchers put forward evidence for a previously unknown population of Altai hunter–gatherers, which appear to be an admixture (i.e., a mixture of isolated populations) of two different groups present in Siberia during the last Ice Age.

Genetic analysis indicated that these people were descended from both Siberian and ancient North Eurasian people. They also discovered evidence of ancient Northeast Asian ancestry around 1,500 kilometers further west than they had anticipated, as well as a 7,000-year-old individual in the far east of Russia with ancestral links to hunter–gatherer groups in the islands of present-day Japan. Together, these findings demonstrate the surprising mobility of these ancient foraging communities.

Furthermore, the researchers also found evidence for the movement of people in the other direction across the Bering Sea from North America into North Asia. This included indications of multiple periods of gene flow over the last 5,000 years which reached the Kamchatka Peninsula in eastern Russia and as far as central Siberia.

Temporal gaps remain

Overall, Posth and colleagues' findings indicate that ancient populations in North Asia frequently migrated and mixed with each other, rather than remaining isolated. However, Posth elaborates on some of the limitations of this kind of study: “The small sample size is often an issue in ancient DNA studies, but skeletal material is extremely limited for ancient hunter–gatherer individuals from this region. Therefore, even data from a handful of individuals can provide unexpected insights and contribute to the understanding of human history in our deeper past,” he explains. “There are still large temporal gaps across this huge geographic region to fill with more interdisciplinary archeological and ancient DNA research.”

Reference: Wang K, Yu H, Radzevičiūtė R, et al. Middle Holocene Siberian genomes reveal highly connected gene pools throughout North Asia. Current Biology. 2023;0(0). doi: 10.1016/j.cub.2022.11.062

Dr. Cosimo Posth was speaking to Sarah Whelan, Science Writer for Technology Networks.