Humans And Neanderthals Hooked Up Three Times. Here’s Where It Happened

Like Ross and Rachel, modern humans and Neanderthals had something of an on-again, off-again love affair. Yet while Friends may have gone extinct after 10 seasons, our ancient ancestors repeatedly reunited over hundreds of thousands of years, and new research may have pinpointed exactly where on the planet these romantic episodes occurred.

Previous studies have identified three waves of gene flow between the two human species, with the first interbreeding event taking place some 250,000 to 200,000 years ago. A second hook-up then happened around 120,000 to 100,000 years ago, followed by a final fling roughly 60,000 to 50,000 years ago.

Recently, it was demonstrated that the second of these get-togethers likely went down in the Zagros Mountains, which stretch across the Persian Plateau and were inhabited by both modern humans and Neanderthals at the time of this middle mating event. To learn more about the most recent admixture, the authors of an as yet un-peer-reviewed study analyzed all known archaeological sites showing evidence of occupation by the two lineages between 60 and 50 millennia ago.

They also analyzed paleoenvironmental data to identify regions capable of supporting large populations of both Homo sapiens and Neanderthals at the same time. Overall, they found that the most suitable habitats for ancient members of our own species were in southern Europe, northern and southern Africa, and large patches of Asia.

Neanderthals, meanwhile, are likely to have thrived along the coasts of the Mediterranean and the Black Sea. Seeking regions where the two hominids may have overlapped, the researchers identified the Iberian Peninsula and the Levant as the most likely settings for the third and final installment of our inter-species romance.

“The most suitable habitats of Neanderthals were located in Western Europe particularly the Iberian Peninsula at [60-50,000 years ago] where Neanderthals and modern humans live[d] alongside each other,” write the study authors. They therefore conclude that the region encompassing modern-day Spain and Portugal was “a highly probable area for the two species interbreeding.”

Around the same time, groups of Homo sapiens were flowing out of Africa and into Eurasia via a key corridor running through the Levant, which includes the Mediterranean shores of the Middle East. Though smaller than the Iberian Peninsula, this highly important region was something of a hominin melting pot during the Middle and Late Pleistocene, where populations of Homo sapiens, Neanderthals, and other human lineages lived side by side.

Putting all of this evidence together, the researchers say that these two areas were likely to have seen considerable species overlap at the time of the third interbreeding event, and that modern humans and Neanderthals may have done the dirty in either of these locations. Not wishing to sit on the fence, though, the authors put their money on the Levant, which they describe as the “main potential interbreeding area.”

The study is currently available as a preprint on bioRxiv.