‘Neanderthals interbred with early humans’

Scientists claim to have found new evidence which confirms that early modern humans,which left Africa some 300,000 to 750,000 years after Neanderthals,probably interbred with the physically stronger hominids.

Scientists claim to have found new evidence which confirms that early modern humans,who left Africa some 300,000 to 750,000 years after Neanderthals,probably interbred with the physically stronger hominids.

An international team,which compared the genomes of more than 6,000 modern humans with that of the hominids,found that a small part of the human X chromosome,which originates from Neanderthals,is present in about nine per cent of people from outside of Africa.

“This confirms recent findings suggesting the two populations interbred,” said Damian Labuda,of the University of Montreal,who led the research.

“Our genetic identity as Homo sapiens traces back much farther than people assumed,” he was quoted as saying by The Vancouver Sun.

Labuda believes the interbreeding must have happened early on in the evolution of modern humans in and around the Middle East,where both populations overlapped for a period of about 30,000 to 50,000 years.

About a decade ago,Labuda identified a small piece of DNA in the human X chromosome of non-African populations that looked different from that of sub-Saharan African groups.

He hypothesised the bit of DNA must have come from an archaic population — perhaps Neanderthals — but there was no way of being sure.

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When Neanderthal genome sequence was made available in 2010,Labuda and his team compared it to over 6,000 different X chromosomes from contemporary people on all continents.

The findings,published in the journal Molecular Biology and Evolution,showed that the Neanderthal sequence was present in all sequences except those from sub-Saharan Africa. About nine per cent of all the X chromosomes studied carried a piece of the Neanderthal DNA.

The X chromosomes from sub-Saharan Africa did not show the Neanderthal sequence because Neanderthals evolved in Eurasia. “We were very lucky to pick up a piece of DNA from the X chromosome,” Labuda said.

The small segment of X chromosome codes for a protein,Labuda explained,and even though it is a very tiny piece of DNA,it could point to more fragments of Neanderthal origin.

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The next step will be to study all the genetic similarities and learn about the dynamics of interbreeding.

This can show us more about the origins of our DNA and how it is structured,he said.

There is also archaeological evidence the two hominid groups interacted,said Pamela Willoughby,a paleolithic archaeologist at the University of Alberta in Edmonton.

“The first opportunity for them to come into contact with each other is between 40,000 and 60,000 years ago,” said Willoughby.

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There are Neanderthal sites in Israel and Iraq that correspond with the time when Homo sapiens was leaving Africa and settling in other parts of the world,she said.

Neanderthals first appeared around 400,000 years ago and went extinct about 30,000 years ago. Scientists have always wondered whether the physically stronger Neanderthals ever intermixed with humans.

In 2010 a team of scientists led by Ed Green,of the University of California,Santa Cruz,was able to extract enough DNA from fossils to have one copy of 60 per cent of the entire Neanderthal genome.