Early humans may have had romantic rendezvous with Neanderthals much earlier than previously thought. While scientists have long known that some ancient humans intermingled with our stocky cousins, a new study suggests that the relations could have started tens of thousands of years earlier than previously suggested.
Genomic analysis of a Siberian Neanderthal women discovered in the Altai mountains revealed bits of modern human DNA, Will Dunham reports for Reuters, which scientists traced back to hominid trists roughly 100,000 years ago.
In 2010, scientists discovered strands of Neanderthal DNA still lingering in modern Europeans and Asians—as much as one to two percent, reports Carl Zimmer for The New York Times. This genetic mark is a remnant of the ancient European and Asian ancestors who journeyed out of Africa into Neanderthal territory around 50,000 to 65,000 years ago.
But the latest study, published in the journal Nature, identifies a much older period of hominid coupling and DNA exchange, reports Colin Barras for New Scientist. Since Neanderthals never made it to Africa, it may represent an early wave of human explorers.
An international team of scientists compared DNA from 500 living Africans—who do not have the Neanderthal genetic markings—with four extinct human ancestors, including a Siberian Denisovan and Neanderthal, and two European Neanderthals.
This analysis showed that the Siberian Neanderthal shares traces of DNA with modern Africans, much more so than the Siberian Denisovan or European Neanderthals, reports Barras.
But how do scientists know when the co-mingling occurred? Zimmer explains: “When DNA gets passed down through the generations, it gets shuffled into new arrangements that can be used to build a sort of timeline.” And this timeline suggests that the DNA entered the Siberian Neanderthal gene pool roughly 100,000 years ago.
The scientists were initially skeptical of the patterns they saw in the data. “We poked and prodded and poked and prodded, and couldn’t get it to go away,” Adam Siepel, geneticist at the Cold Spring Harbor Laboratory and co-author of the new study, tells Zimmer.
This finding challenges the current narrative that human migration out of Africa took place around 50,000 years, Zimmer writes, raising the possibility that an earlier movement of human explorers did occur.
Limited archaeological evidence suggests modern humans were living in the Arabian peninsula or eastern Mediterranean around that time, Barras writes. Many also point to last year’s discovery of 47 modern human teeth in southeast China, dated to be around 80,000 to 120,000 years old. Yet no matter where the coupling occurred, this early group of humans likely went extinct, leaving no modern descendants, Justin Worland reports for Time.
“I think at this point we’ve convinced everybody the observation is real,” he says. “But the story behind the observation is still very much in dispute.”