In 2002, cavers unearthed a jawbone in Peștera cu Oase of southwestern Romania. While it had some Neanderthal features, the bone belonged to an anatomically modern human male who lived 37,000 to 42,000 years ago. Now, according to researchers analyzing DNA extracted from the bone, this modern human – one of the earliest humans in Europe – had a Neanderthal relative just four to six generations ago. The work, published in Nature this week, suggests that our species and Neanderthals mated in Europe far more recently than we thought.
After dispersing from Africa, anatomically modern humans began spreading across Europe between 45,000 and 35,000 years ago. During that time, Neanderthals vanished. They had been living in Europe since before 300,000 years ago, and we know that Neanderthals contribute 1% to 3% of the DNA of everyone outside of sub-Saharan Africa today. So our early ancestors had sex with Neanderthals, we’re just not sure when and how often it happened. Previous estimates of human-Neanderthal intermixing have ranged wildly from 37,000 to 86,000 years ago.
Now, a large international team led by Harvard’s David Reich and Svante Pääbo from Max Planck Institute for Evolutionary Anthropology have used a dentistry drill to remove two samples of bone powder from the Oase 1 mandible where a larger sample was previously removed for radiocarbon dating.
For their analysis, the researchers prepared two DNA extracts from 25 and 10 milligrams of bone powder taken from the Oase 1 jawbone. Svante Pääbo/Max Planck Institute for Evolutionary Anthropology
When they analyzed the DNA extracted from those samples, they discovered that between 6% and 9.4% of Oase 1’s genome is derived from Neanderthals. That’s more than any other human ever sequenced. Furthermore, he had a Neanderthal ancestor removed by only four to six generations: The mixing event occurred less than 200 years before he was born.
“The data from the jawbone imply that humans mixed with Neanderthals not just in the Middle East but in Europe as well,” first author Qiaomei Fu from the Chinese Academy of Sciences says in a statement. Just last year, a study based on DNA extracted from a western Siberian thighbone placed the Middle Eastern interbreeding event at 50,000 to 60,000 years ago.
However, because Oase 1 was more genetically similar to present-day East Asians and Native Americans than to Europeans, he must have been part of a population that mixed with Neanderthals but didn’t contribute to later Europeans. “It is evidence of an initial modern human occupation of Europe that didn't give rise to the later population,” Reich says in a statement. “There may have been a pioneering group of modern humans that got to Europe, but was later replaced by other groups.”