A Trinity College Dublin-led team of researchers has sequenced the genomes of two ancient hunter-gatherers from the Caucasus, as it reports in Nature Communications.
These ancient samples hail from western Georgia at the eastern boundary of Europe, and one was traced back to the Late Upper Paleolithic, or about 13,300 years ago, and the other to the Mesolithic, or about 9,700 years ago. Trinity's Daniel Bradley and his colleagues sequenced these samples to 1.4-fold and 15.4-fold coverage, respectively.
These Caucasus hunter-gatherers, the researchers say, belong to a distinct clade that split from western hunter-gatherers about 45,000 years ago, giving insight into the ancestral sources of modern Europeans.
"Modern Europeans are a mix of ancient ancestral strands," Bradley tells Reuters. "The only way to untangle the modern weave is to sequence genomes from thousands of years ago, before the mixing took place."
These Caucasus hunter-gatherers might represent a fourth strand — in addition to western hunter-gatherers, early farmers, and ancient North Eurasians — that has contributed to the genetic makeup of Europeans, Reuters notes. They also appear to have contributed to the ancestry of people from Central Asia and the Indian subcontinent.