NEW YORK (GenomeWeb) – New ancient DNA research appears to support the notion that an Iron Age rise in Siberian ancestry in Eastern Baltic populations coincided with the introduction of Finnic languages from the Uralic language family to the region.
"Since the transition from Bronze to Iron Age coincides with the diversification and arrival time of Finnic languages in the Eastern Baltic proposed by linguists, it is plausible that the people who brought Siberian ancestry to the region also brought Uralic languages with them," first and co-corresponding author Lehti Saag, a PhD student at the University of Tartu's Institute of Genomics, said in a statement.
For a study published online today in Current Biology, researchers from Estonia, Belgium, Russia, the UK, and Sweden sequenced ancient DNA from dozens of tooth samples from Late Bronze Age, Iron Age, or Medieval populations with stone-cist or tarand grave types in Estonia and Russia. In addition to an uptick in genetic variants in Bronze Age samples that are associated with now-common Northern European phenotypes such as lactose tolerance or light skin and eye coloring, they found that Siberian ancestry began appearing in the admixed European hunter-gatherer, early farmer, and steppe populations in the Late Bronze Age or early Iron Age.
Together, the team explained, the data hints that eastern migrations into the region in the Iron Age contributed to language changes that led to the Finnic forms that characterize the region, while earlier mixing with individuals from Western hunter-gatherer groups during the Bronze Age may have helped introduce some well-known physical features to the Eastern Baltic.
"The Bronze Age individuals from the Eastern Baltic show an increase in hunter-gatherer ancestry compared to Late Neolithic people and also in the frequency of light eyes, hair, and skin and lactose tolerance," senior and co-corresponding author Kristiina Tambets, a genomics researcher at the University of Tartu, said in a statement.
The researchers started with tooth samples for 56 ancient individuals going back between 400 and 3,200 years, found in Late Bronze Age stone-cist graves (associated with Scandinavian cultures) at several sites in Estonia, Pre-Roman Iron Age and Medieval cemeteries in Estonia, including tarand-type cemeteries associated with Uralic groups, and burial sites dated to the Pre-Roman and Roman Iron Age in northwestern Russia.
After DNA extraction and sequencing, they were left with sequence data for 33 individuals, which they used for comparing autosomal, Y chromosome, and mitochondrial DNA sequences to one another and to genome from other ancient and modern-day people.
"Studying ancient DNA makes it possible to pinpoint the moment in time when the genetic components that we see in modern populations reached the area, since instead of predicting past events based on modern genomes, we are analyzing the DNA of individuals who actually lived in a particular time in the past," Saag said.
With their analyses, Saag, Tambets, and colleagues detected gene flow from Siberia into the populations on the eastern coast of the Baltic Sea that now speak Uralic languages. That gene flow was especially clear in their Y chromosome analyses, where an N3a haplogroup linked to Siberian populations was identified across multiple European populations with Uralic languages.
"[H]alf of the admittedly small [Iron Age Estonian] sample[s] and over one-third of modern Estonian men share a [Y chromosome N3a haplogroup] — common in other Uralic-speaking populations living much further east and not found in the Eastern Baltic earlier — although the autosomes of [Iron Age Estonian] individuals only show 3 percent to 5 percent Siberian ancestry, on average," the authors wrote.