According to a new study published Monday in Nature, modern humans and Neanderthals may have been interbreeding in Europe as recently as 40,000 years ago.

We're all a little bit Neanderthal. That other species was human — we're all member of the genus Homo — but they didn't have the same physical characteristics as what we'd call a modern human. Scientists are certain that our modern human ancestors interbred with Neanderthals, suggesting that the species didn't go extinct so much as blend in. But pinpointing just when that interbreeding occurred is tricky.

The new study examined the skeletal remains of a man who lived about 40,000 years ago and found that he'd had a Neanderthal ancestor just a few generations back. Dubbed Oase 1, the man had more Neanderthal DNA than any modern human ever examined — between 6 and 10 percent compared with the 3 percent average today — and the Neanderthal DNA segments he had were long, indicating that they came from an ancestor just four generations back or so. That adds weight to the idea that humans and Neanderthals actually co-existed for quite some time, and that our traces of Neanderthal DNA aren't the result of a few sexual encounters — but rather a long-term mingling of the species.

Until now, the only real evidence of human and Neanderthal mixing came from populations in the Middle East some 50,000 to 60,000 years ago. Those are the couplings that led to our own lineage.

But the new study shows that a European had recent Neanderthal contributions to his DNA in addition to those early fragments from African couplings, indicating that humans and Neanderthals lived together in Europe, too. That makes sense, since recent studies have argued that humans and Neanderthals lived in the same parts of Europe for some 5,000 years, and that Neanderthals were much more "modern" than we give them credit for — creating art and jewelry, for example. So it would be surprising if the two species had avoided each other on the European continent.

It seems that the individual studied in the new paper wasn't part of a branch that would lead to the humans alive today — his descendants died out. That could very well be due to the interbreeding itself: Perhaps, as is the case with most hybrids, the interspecies offspring were prone to infertility and disease. But even though this group didn't make it, we now know they existed.

“This is the only interbreeding in Europe that we know about so far,” Svante Pääbo, director of the Max Planck Institute for Evolutionary Anthropology in Leipzig and lead author of the study, told the Guardian. “It shows us that the very earliest modern humans that came to Europe really mixed with the local Neanderthals here. It’s not just something that happened early on when they came out of Africa.”

Now that the intermingling is all the more certain, there are some exciting questions to answer. What was the cultural exchange between these two species like? What was life like for the child of a human and a Neanderthal? We used to think that modern man had violently expunged the Neanderthal from the planet — or at least outcompeted his cousins using superior intellect. But if humans and Neanderthals had centuries to get to know each other, then the story of our success and their failure becomes much more interesting.

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