http://dispatchesfromturtleisland.blogspot.com/2023/03/genetic-diversity-among-european-hunter.html?m=1
About 14,000 years ago, when temperatures across the continent rose sharply in the space of a few centuries, archaeologists recognized cultural changes. But they thought the changes reflected an existing population adapting to hunt in warmer, more heavily forested landscapes. Instead, DNA shows an almost complete population replacement: The people who survived the glacial maximum, known as the Magdalenians, all but vanish and are replaced by populations moving north from postglacial Italy.
The study also looked at the final era of hunter-gatherers in Europe, beginning 10,000 years ago as warming continued to transform the open steppe to dense forests and rich wetlands. Here, again, the genes revealed a surprising wrinkle: Despite broadly similar hunting and gathering lifestyles, people in Western Europe remain genetically distinct from those east of the Baltic Sea.
They even looked different: Genetic data suggest that before the arrival of farmers in northern Europe around 6000 B.C.E., hunter-gatherers in Western Europe had dark skin and light eyes. People in Eastern Europe and Russia, meanwhile, had light skin and dark eyes. Most surprising, despite the lack of geographic barriers between modern-day Germany and Russia, the two groups spent millennia not mingling. “From 14,000 years ago to 8000 years ago, they do not mix at all,” Posth says. But he acknowledges that the team’s samples don’t cover the continent completely, and the likely contact zones—in Poland and Belarus, for example—lack samples. More genetic data from those areas might show the two populations mixing locally