Genetic Research Validates That Non-Africans Are Part Neanderthal

Part of the human X chromosome originates from Neanderthals, and it is found only in people outside Africa, according to an international team of researchers.

The study was led by Damian Labuda of the department of pediatrics at the University of Montreal (Canada) and the University’s CHU Sainte-Justine Research Center. The findings of the research were published in the July 2011 issue of the journal Molecular Biology and Evolution. “This confirms recent findings suggesting that the two populations interbred,” said Dr. Labuda. His team places the timing of such intimate contacts and/or family ties early on, probably at the crossroads of the Middle East.

Neanderthals, whose ancestors left Africa approximately 400,000 to 800,000 years ago, evolved in what is now chiefly France, Spain, Germany, and Russia, and are believed to have lived until about 30,000 years ago. In the meantime, early modern humans left Africa about 80,000 to 50,000 years ago. The question has always been whether the physically stronger Neanderthals, who possessed the gene for language and may have played the flute, were a distinct species or could have interbred with modern humans. The answer is yes, the two lived in close association.

“In addition, because our methods were totally independent of Neanderthal material, we can also conclude that previous results were not influenced by contaminating artifacts,” added Dr. Labuda.

Dr. Labuda and his team almost 10 years ago had identified a piece of DNA (a haplotype) in the human X chromosome that seemed different and whose origins they questioned. When the Neanderthal genome was sequenced in 2010, they then compared 6,000 chromosomes from all parts of the world to the Neanderthal haplotype. The Neanderthal sequence was 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. This is a very nice result, and further analysis may help determine more details,” said Dr. Nick Patterson, of the Broad Institute of the Massachusetts Institute of Technology (MIT; Cambridge, MA, USA) and Harvard University (Cambridge, MA, USA), a key researcher in human ancestry who was not involved in this study.

“Dr. Labuda and his colleagues were the first to identify a genetic variation in non-Africans that was likely to have come from an archaic population. This was done entirely without the Neanderthal genome sequence, but in light of the Neanderthal sequence, it is now clear that they were absolutely right,” added Dr. David Reich, a Harvard Medical School geneticist, one of the principal researchers in the Neanderthal genome project.

Therefore, hypothesized Dr. Labuda, did these exchanges contribute to our success across the world? “Variability is very important for long-term survival of a species,” said Dr. Labuda. “Every addition to the genome can be enriching.”

Related Links:
University of Montreal
CHU Sainte-Justine Research Center