Origins

[wall_rus]

What Were the Consequences of Early Human & Neanderthal Interbreeding?

February 28, 2012

http://www.dailygalaxy.com/my_weblog/2012/02/what-was-the-impact-of-early-human-neanderthal-interbreeding.html?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+TheDailyGalaxyNewsFromPlanetEarthBeyond+%28The+Daily+Galaxy+--Great+Discoveries+Channel%3A+Sci%2C+Space%2C+Tech.%29

Early modern humans left Africa about 80,000 to 50,000 years ago. The question has long been whether the physically stronger Neanderthals, who possessed the gene for language and may have played the flute, were a separate species or could have interbred with modern humans. The answer is yes, the two lived in close association.

In July 2011, an international team of researchers led by Damian Labuda of the Department of Pediatrics at the University of Montreal and the CHU Sainte-Justine Research Center announced that the human X chromosome originated from Neanderthals and is found exclusively in people outside Africa, which confirmed recent findings suggesting that the two populations interbred," said 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 about 400,000 to 800,000 years ago, evolved in what is now mainly France, Spain, Germany and Russia, and are thought to have lived until about 30,000 years ago.

"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 Labuda.

Labuda and his team almost a decade ago had identified a piece of DNA (called a haplotype) in the human X chromosome that seemed different and whose origins they questioned. When the Neanderthal genome was sequenced in 2010, they quickly compared 6000 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," said Dr. Nick Patterson, of the Broad Institute of MIT and Harvard University, a major 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!" adds Dr. David Reich, a Harvard Medical School geneticist, one of the principal researchers in the Neanderthal genome project.

"Variability is very important for long-term survival of a species," concluded Labuda. "Every addition to the genome can be enriching."