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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.