An early European that lived between 37,000 and 42,000 years ago probably had a Neanderthal great-great-grandparent — or a Neanderthal great-great-great-great-grandparent, at the very least.
6 to 9 percent of this human's DNA came from Neanderthals
By analyzing the DNA contained in a human jaw found in a Romanian cave, scientists have found that about 6 to 9 percent of this individual's DNA came from Neanderthals. The finding means that his genome — the DNA analysis also identified him as male — is more Neanderthal than any other human sequenced to date.
This is "quite lucky and unexpected," says Qiaomei Fu, a geneticist at Harvard University and a co-author of the study, published today in Nature. A human "this close to Neanderthals has not been found before."
Approximately 40,000 years ago, Neanderthals went extinct, but their DNA lives on. Europeans and Asians inherited between 1 percent and 4 percent of their genetic material from Neanderthals. This means that Eurasians probably had a lot more Neanderthal in them once upon a time; with each generation, the DNA that’s passed down from one ancestor is diluted. This gradual dilution is the marker that geneticists used to estimate the amount of generations separating this early European from his Neanderthal ancestors. Indeed, the surprising length of his Neanderthal-derived DNA hints that one of his ancestors probably had sex with a Neanderthal about 200 years before his birth.
Credit: Svante Pääbo, Max Planck Institute for Evolutionary Anthropology
The study adds to our understanding of human interactions with Neanderthals. Chances are, interbreeding happened more often than previously thought. That said, the population to which this human belonged didn't go on to contribute much of its DNA — if any — to later Europeans. It’s therefore possible that he participated in an early migration of modern humans to Europe that interacted with Neanderthals, and eventually went extinct.
A human "this close to Neandertals has not been found before."
Scientists have named this human "Oase 1," after the cave in which he was found. His genome raises a lot of questions, they say. For example, because interbreeding occurred 200 years before Oase 1 was born, the act of interbreeding must have taken place in Romania, explains Israel Hershkovitz, an anthropologist at Tel Aviv University who didn’t take part in the study. "Yet there is no fossil evidence to suggest that Neanderthals were indeed present in Romania at this time," he says. And because we only have this one specimen to go on, it’s unclear how prevalent this individual’s genetic mixture was at the time.
Still, interbreeding between humans and Neanderthals appears to have occurred at different geographical areas outside Africa and at different times, Hershkovitz says. Signs of interbreeding have been found in Siberia and in the Middle East. "So it was not a Romeo and Juliet story," Hershkovitz says — "but rather 'one thousand and one nights' stories."