MONTREAL, July 18 (UPI) -- Some of the human X chromosome is from Neanderthals and, found exclusively in people outside Africa, hints at interbreeding with modern humans, a study says.
"This confirms recent findings suggesting that the two populations interbred," said Damian Labuda of the University of Montreal in an article published in the journal Molecular Biology and Evolution.
Neanderthals, who left Africa about 400,000 to 800,000 years ago, evolved in what is now mainly France, Spain, Germany and Russia, and are thought to have survived until about 30,000 years ago.
Early modern humans left Africa about 80,000 to 50,000 years ago.
Scientists have long wondered if the physically stronger Neanderthals, who possessed the gene for language, were a separate species or could have interbred with modern humans.
The new study suggests the two lived in close association and did interbreed.
When the Neanderthal genome was sequenced in 2010, a small piece of the sequence of DNA called a haplotype was found to be present in peoples across all continents, except for sub-Saharan Africa, and including Australia.
"There is little doubt that this haplotype is present because of mating with our ancestors and Neanderthals," said Nick Patterson of MIT and Harvard University, a major researcher in human ancestry who was not involved in the Montreal study.
"This is a very nice result, and further analysis may help determine more details."