New genetic research suggests that modern Europeans descended from three separate ancestral groups rather than just two groups. A new study, published Thursday, September 18th, highlights that around 20% of the DNA of modern Europeans derives from a group called northern Eurasians who arrived sometime around six or seven thousand years ago.
Scientists have had difficulty reconciling the gene pool of modern Europe with European genetics. Evidence from archaeological research and previous genetic comparisons suggested Europeans had descended from Middle Eastern farmers who migrated to Europe about 7,500 years ago and the local hunter-gatherer societies inhabiting most of the continent at the time. The new study makes it clear that another genetically distinct group of hunter gathers also migrated to Europe 500 to 1500 years after the farming societies had arrived.
European genetics: Statement from study authors
“The surprising finding was that present-day Europeans trace their ancestry back to three and not just two ancestral groups as previously thought,” explained study co-author Alan Cooper, the director of the Australian Centre for Ancient DNA, in a statement released today.
Of particular interest, the indigenous European hunter-gatherers had a “striking combination of dark skin and blue eyes that doesn’t exist anymore,” one the study’s lead authors, David Reich of Harvard Medical School, elaborated in an interview with the BBC.
Modern Europeans more closely resemble the light-skinned Middle Eastern farming peoples that arrived in Europe around 7,000 years ago.
“There’s an evolutionary argument about this — that light skin in Europe is biologically advantageous for people who farm, because you need to make vitamin D,” Reich noted. “Hunters and gatherers get vitamin D through their food — because animals have a lot of it. But once you’re farming, you don’t get a lot of it, and once you switch to agriculture, there’s strong natural selection to lighten your skin so that when it’s hit by sunlight you can synthesize vitamin D.”
European genetics: Mysterious North Eurasians
Johannes Krause, a geneticist at the University of Tübingen and co-director of the Max Planck Institute for History and the Sciences in Germany not affiliated with the research, said the mysterious North Eurasians are somewhat of a missing link in European genetics. The ancient North Eurasians “connect all modern Europeans and Native Americans,” he said.
Physical anthropologists also note that the Northern Eurasians are genetically related to the people who migrated across a frozen land bridge to the Americas around 15,000 years ago, and that their genetic background is similar to Native Americans.