Neanderthal DNA lives on in modern humans, research shows

The ancestors of most modern humans mated with Neanderthals and made off with important swaths of DNA that helped them adapt to new environments, scientists reported Wednesday.

Some of the genes gained from these trysts linger in people of European and East Asian descent, though many others were wiped out by natural selection, according to reports published simultaneously by the journals Nature and Science.

The stretches of Neanderthal DNA that remain include genes that altered hair and pigment, as well as others that strengthened the immune system, the scientists wrote. Together, they offer intriguing hints about how Neanderthal genes may have helped humans adapt as they spread around the globe.

They also add to evidence that Neanderthals linger in us, about 30,000 years after they mysteriously vanished.

"They are not fully extinct, if you will," said geneticist Svante Paabo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, a coauthor of the Nature study. "They live on in some of us today a little bit."

Genes controlling keratin, a key component in the development of skin and hair, stand out as the strongest Neanderthal signal in a modern genome, Paabo said. Precisely how these may have helped change modern physical characteristics remains unresolved, he added.

The new studies confirm earlier findings that modern humans did more than bump elbows with Neanderthals when they encountered them after they left Africa.

An estimated 1% to 3% of the human genome comes from Neanderthals, suggesting that members of the two species mated perhaps 300 times about 50,000 years ago, said Joshua M. Akey, a population geneticist from the University of Washington and lead author of the study published in Science. There's no way to tell whether those encounters happened about the same time or were spread out over many generations, he said.

"Individually, we are a little bit Neanderthal," Akey said. "Collectively, there is a substantial part of the Neanderthal genome that's still floating around in the human population that's just shattered into different pieces, and everyone has slightly different parts."

Confirming that there are slivers of Neanderthal DNA in modern humans is one thing; knowing what effect it had on us is another, said UC Berkeley biologist Montgomery Slatkin, who has done similar research on Neanderthal genetics but was not involved in either study. "Now there is convincing evidence that indeed some [genes] were selected in humans."

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Neanderthal DNA lives on in modern humans, research shows