Next time someone calls you a caveman, tell them it’s in your genes.
After comparing thousands of gene sequences, researchers at the University of Montreal have confirmed that — with the exception of people in sub-Saharan Africa — people today carry a tiny bit of the same X chromosome carried by Neanderthals.
“This confirms recent findings suggesting the two populations interbred,” said Damian Labuda, an expert in human population genetics at the University of Montreal, who led the team made up of Canadian and international researchers. The findings were published in the July issue of the journal Molecular Biology and Evolution.
“Our genetic identity as Homo sapiens traces back much farther than people assumed,” he said. According to Labuda, 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 hypothesized the bit of DNA must have come from an archaic population — perhaps Neanderthals — but there was no way of being sure.
When the Neanderthal genome sequence was made available in 2010, Labuda and his team compared it to more than 6,000 different X chromosomes from contemporary people on all continents. They found 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,” he 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. 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.
Labuda pointed to research by Stanford University’s Peter Parham, that explores how our genetic inheritance from Neanderthals could contribute to immune strength.
“Acquiring new diversity can be advantageous,” Labuda said.
There is archeological evidence that the two hominid groups interacted.
“The first opportunity for them to come into contact with each other is between 40,000 and 60,000 years ago,” said Pamela Willoughby, a paleolithic archaeologist at the University of Alberta in Edmonton. 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.
“In Western Europe there’s definitely archaeological evidence for interaction,” she added. Beads, bone tools and jewelry similar to that of Homo sapiens of the same period have been found at Neanderthal sites in Spain, for example. It does not appear that Neanderthals made these kinds of implements before Homo sapiens arrived on the continent, she said.
Scientists have long questioned whether Neanderthals interbred with early modern humans.
Neanderthals originated in Africa and evolved about 800,000 to 400,000 years ago and migrated to Europe and Asia. They inhabited the territory that is now France, Spain, Germany and Russia, and are estimated to have gone extinct about 30,000 years ago.
Homo sapiens evolved from the same common ancestor much later, about 150,000 years ago, and left Africa around 50,000 to 80,000 years ago.
Neanderthals were physically similar to modern humans but stronger, with shorter, stockier bodies, angled cheek bones and a large nose. Their brains were the same size as Homo sapiens’ and they also possessed the gene for language.
Neanderthals also controlled fire, lived in shelters, and occasionally made symbolic or ornamental objects. The first Neanderthal fossil was discovered in 1856 in Germany in the Neander Valley, hence the hominid’s name.
Postmedia News
Source: National Post
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