Neanderthals, Humans Interbred, DNA Proves

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A reconstructed head based on a Neanderthal skull found in France is shown.
Sven Traenkner (c), "Safari zum Urmenschen" ("Safari to Human Ancestors") exhibition, Senckenberg Research Institute and Natural History Museum, Frankfurt, Germany

THE GIST

- A newly mapped Neanderthal genome provides strong evidence that humans and Neanderthals interbred.

- Between 1-4 percent of the DNA of many humans living today likely came from Neanderthals.

- People of European and Asian heritage are most likely to carry the Neanderthal genes.

It's official: Most of us are part Neanderthal. The first draft sequence of the Neanderthal genome has provided the strongest evidence yet that modern humans and Neanderthals interbred and that all non-Africans today have Neanderthal gene fragments in their genetic codes.

Although the Neanderthal contribution to the DNA of these individuals is estimated at being just one to four percent of the total, the finding, published in the latest issue of the journal Science, helps to resolve the long-standing controversy over whether or not humans mated with Neanderthals when the two groups encountered each other outside of Africa.

It also gives new life to Neanderthals that, as a species, went extinct 30,000 years ago.

"Neanderthals live on in non-Africans," co-author David Reich told Discovery News. "At least some Neanderthals were absorbed into the modern human population."

Photos: Humans Vs. Neanderthals: How Did We Win?

Reich is an associate professor of genetics at Harvard University who also serves as a population geneticist at the Broad Institute of MIT and Harvard.

He and his colleagues analyzed over one billion DNA fragments taken from Neanderthal bones -- dating to approximately 38,000 years ago -- found in Croatia, Germany, Russia and Spain.

Although 95 percent of the fragments consisted of bacteria and microorganisms that colonized the Neanderthal remains, special DNA isolation and anti-contamination measures enabled the scientists to piece together over 60 percent of the entire Neanderthal genome.

The researchers next compared the Neanderthal DNA to samples taken from present-day humans in southern Africa, western Africa, China, France and Papua New Guinea.

One of the first determinations concerned the point at which humans diverged from their common ancestor with Neanderthals, who lived in much of Europe and western Asia before they went extinct.

"According to our results, the ancestors of Neanderthals and modern humans went their separate ways about 400,000 years ago," said co-author Jim Mullikin, a computational geneticist at the National Human Genome Research Institute.

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