New DNA Reveals the Closest Link Yet to Neanderthals

Scientists have known for some time now that modern humans interbred with Neanderthals. It appears the two species coexisted for at least 5,000 years, during which time they exchanged genes and possibly even culture, resulting in present-day rates of between 2-4% of Neanderthal DNA among contemporary European populations. But new analyses of a jawbone reveals an even greater tie to Neanderthals, for it turns out, the owner of the jaw shared a more recent ancestor than any individual yet discovered.

The jaw was discovered tucked within the cave system of Pestera cu Oase in southwestern Romania back in 2002. Dating to over 34,000 years ago, the individual inhabited the region during a time when modern humans and Neanderthals would have come in contact. At the time of its discovery, scientists had theorized about its link to Neanderthals based on the extremely large molars within the jaw.

The researchers were able to isolate and sequence segments of DNA from the jaw, which revealed that an astonishing 6% - 9% of the Oase individual's genome originated from a Neanderthal ancestor. This suggests a Neanderthal relative as recent as 4-6 generations back, making it the most closely related individual yet discovered.

"It's an incredibly unexpected thing," says Professor David Reich, a professor at Harvard Medical School and co-author of the paper that was recently published in the journal Nature. "In the last few years, we've documented interbreeding between Neanderthals and modern humans, but we never thought we'd be so lucky to find someone so close to that event."

Although the jaw provides clues to the recent interbreeding between humans and Neanderthals, the DNA indicates the man was not ancestral to modern Europeans.

"This sample, despite being in Romania, doesn't yet look like Europeans today," Reich says. "It is evidence of an initial modern human occupation of Europe that didn't give rise to the later population."

"There may have been a pioneering group of modern humans that got to Europe, but was later replaced by other groups."

Neanderthals are considered our closest extinct human relative. They sported shorter, stockier bodies than modern humans, probably an adaptation to living in cold environments. Though long branded as less intelligent than moderns, based on misinterpretations of some of the first fossil finds, we now know that Neanderthals were efficient hunters that used sophisticated tools, controlled fire, and occasionally produced symbolic and ornamental objects.

The Neanderthals occupied Europe and parts of Asia from about 200,000 years ago until around 40,000 years ago. Modern humans, who are believed to have migrated out of Africa within the past 200,000 years based on DNA evidence, obviously came in contact with Neanderthals and may have had a hand in their demise. Scientists continue to search for clues surrounding our close cousin's extinction.