An international research team led by the Max Planck Institute for Human History in Jena has reconstructed the population history of the Baikal region with the help of ancient human genomes, prehistoric pathogens and stable isotope analyses, discovering the oldest link between the inhabitants of Siberia and the Indians of North and South America. The study, published in the journal Cell, also demonstrates the human mobility and connectivity of the inhabitants of Eurasia in the early Bronze Age.
For more than 20,000 years, people have lived in the vicinity of Lake Baikal and left a variety of archaeological traces there. Analysis of ancient genomes from the region has revealed multiple genetic upheavals and mixing events. This suggests that the transition between Stone Age hunter-gatherers and Bronze Age nomads was accompanied by human mobility and complex cultural interactions. However, the nature and timing of these interactions are still largely unknown.
A new study published in the journal Cell reports the results of analyzing 19 newly sequenced ancient human genomes from the Baikal region, including one of the oldest genomes studied so far from the region. The work was carried out at the Max Planck Institute for Human History in Jena and sheds detailed light on the population history of the Baikal region and reveals genetic links with the Native Americans dating back to the Stone Age, as well as human connections throughout Eurasia during the early Bronze Age.
The oldest genetic link to America
“This study reveals the oldest known link between Stone Age residents of Siberia and America’s first inhabitants,” said He Yu, the study’s first author. “We believe that this link will be very important for future studies of the population history of Native Americans.”
Previous studies have pointed to a link between the Siberian and American populations. However, a 14,000-year-old individual analyzed as part of this study is the oldest known individual to carry the genetic mix of Native Americans. Using state-of-the-art molecular biology techniques, the research team was able to reconstruct this genome from the fragments of a tooth that was excavated in 1976 at the Ust-Kyahta-3 site.
This individual from southern Siberia is genetically closely related to a younger mesolithic individual found more than 3,000 km northeast in Siberia. Both individuals have the same genetic mix of ancient North Eurasian (ANE) and Northeast Asian (NEA) ancestry found in America’s first inhabitants. This result suggests that the ancestry from which the indigenous peoples of North and South America later emerged was much more widespread than previously thought. There is evidence that this population had frequent contacts with NEA populations, resulting in different genetic admixture ratios in time and space.
“The Stone Age genome from Lake Baikal is a reference point for future research into the genetic history of Asia and America,” said Cosimo Posth, one of the study’s lead authors. However, further genetic findings from Stone Age populations of Siberia are necessary to find out when and where the native American gene pool came together.
A network of prehistoric connections
In addition to this transcontinental connection, the study represents connectivity within Eurasia. It was detected on the basis of both human and genome of pathogens and stabilizing isotope analysis. By combining these results, the research team was able to provide a detailed description of the population history in the Baikal region. Among other things, at the beginning of the Bronze Age, an epoch characterized by increasing social and technological complexity, genetic links between the Baikal region and inhabitants of the Eastern European steppe could be detected.
The surprising discovery of Yersinia pestis, the pathogen of the plague, in two individuals indicates further far-reaching contacts. Although it was postulated that the spread of Y. pestis was favored by migration of humans from the steppe, the genetic material of the two individuals identified with the pathogen in this study was similar to the genetic material of Northeast Asian individuals and had no steppe genes. In addition, the strains of Y. pestis, with whom the two individuals were infected, are most closely related to a strain identified in an individual from the Baltic region of northeastern Europe. The isotope analysis of one of the infected individuals also revealed a non-local signal, suggesting that this individual came from outside the found region. This is another indication of the high mobility of these Bronze Age pathogens and probably also of the people of that time.
“The appearance of the ancient Y. pestisstrains so far to the east probably indicates long-range mobility during the Bronze Age,” said Maria Spyrou, co-author of the study. Johannes Krause, senior author of the study, concludes: “By generating additional data, we hope to be able to describe in more detail the propagation patterns of this form of Stone Age plague in the future.”
Source: Max-Planck-Institut für Menschheitsgeschichte