Europe wasn't a very hospitable place fifteen millennia ago. The westernmost landmass of the Eurasian continent had endured a long ice age, with glaciers stretching across northern Europe and into the region we now call Germany. But suddenly, about 14,500 years ago, things started to warm up quickly. The glaciers melted so fast around the globe that they caused sea levels to rise 52 feet in just 500 years. Meanwhile, the environment was in chaos, with wildlife trying vainly to adjust to the rapid fluctuations in temperature. Humans weren't immune to the changes, either.
A new, comprehensive analysis of ancient European DNA published today in Current Biology magazine by an international group of researchers reveals that this period also witnessed a dramatic shift in the human populations of Europe. Bloodlines of hunter-gatherers that had flourished for thousands of years disappeared, replaced with a new group of hunter-gatherers of unknown origin.
Researchers discovered this catastrophic population meltdown by sequencing the mitochondrial DNA of 35 people who lived throughout Europe between 35 and 7 thousand years ago. Mitochondrial DNA is a tiny amount of genetic material that's inherited virtually unchanged via the maternal line, and thus it serves as a good proxy for relatedness over time. Two people from the same maternal stock share almost the same mitochondrial DNA, even if separated by thousands of years, because this kind of DNA evolves very slowly.
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