NEW YORK (GenomeWeb) – In contrast to how farming spread into other parts of Europe, a new ancient DNA study suggests it reached the Baltic region primarily through a dispersal of ideas during the so-called Neolithic transition from a hunter-gatherer to agricultural lifestyle.
Researchers from Trinity College Dublin and elsewhere did genome sequencing on samples from eight individuals who lived in present-day Latvia or Ukraine more than 4,800 years ago. As reported online today in Current Biology, they did not detect an influx of genetic ancestry from Anatolian or Levantine agriculturalists during the shift toward farming.
"The findings suggest that indigenous hunter-gatherers adopted Neolithic ways of life through trade and contact, rather than being settled by external communities," co-corresponding author Andrea Manica, a zoology researcher at the University of Cambridge, said in a statement. "Migrations are not the only model for technology acquisition in European prehistory."
The team's analysis also uncovered signs of ancestry from populations in northern Eurasia or Pontic Steppe herders in the Baltic population, hinting that the Indo-European language spread into the region with Steppe individuals arriving in the Bronze Age rather than with Anatolian agriculturalists.
"That we see no farmer-related genetic input, yet we do find this Steppe-related component, suggests that at least the Balto-Slavic branch of the Indo-European language family originated in the Steppe grasslands of the East, which would bring later migrations of Bronze Age horse riders," first author Eppie Jones, a genetics researcher affiliated with Trinity College Dublin and the University of Cambridge, added.
Prior studies — including a 2015 analysis focused on 230 ancient European samples — point to population spread as a catalyst in transforming parts of Europe from hunter-gatherer to agricultural lifestyles during the Neolithic or Stone Age. But agriculture may have arrived by other means as well.
Manica, Jones, and their colleagues used Illumina instruments to do shotgun genome sequencing on half a dozen individuals who lived in Latvia near the Zvejnieki archaeological site, during the Mesolithic or Neolithic going as far back as around 8,300 years. They also did genome sequencing on one Mesolithic and one Neolithic sample from sites along Ukraine's Dnieper River, covering each of the ancient genomes to up to four-fold depth of coverage.
The team's analysis indicated that both Ukrainian samples fell between hunter-gatherer groups from Western and Eastern Europe. The oldest Latvian samples, which were traced back to the Middle Mesolithic, Late Mesolithic, and Early Neolithic periods, clustered in a group that was slightly more related to hunter-gatherers from Western Europe, but had some genetic ties to Eastern Europe hunter-gatherers.
Although their results revealed some Northern Eurasian ancestry in Latvian samples from the Middle Neolithic, the researchers noted that hunter-gatherer ancestry endured in the region. A Late Neolithic Latvian representative had genetic patterns resembling those in European or Steppe groups and hunter-gatherers from the Caucasus, they reported, but lacked any apparent Anatolian ancestry.
From these findings, the team concluded that the "Baltic hunter-gatherer genome remains remarkably untouched until the great migrations of the Bronze Age sweep in from the East," Manica said.