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Neanderthals had human DNA Suggesting Modern Humans Migrated from Africa Earlier than Previously Believed

A Neanderthal woman’s remains that lived about 100,000 years ago in the Altai Mountains, Siberia, have shown that modern humans and Neanderthals mated much earlier than previously thought. As shown by a new study 1 or more of her relatives were human.

It has been known that Neanderthals contributed DNA to modern humans, which resulted in people of the present of Asian descent retaining Neanderthal DNA in their genomes, though this Neanderthal woman provides the first evidence that as a result of interbreeding gene flow also went from modern humans to Neanderthals.

This study, published in the journal Nature, is also the first that provides evidence of modern humans outside Africa as early as 100,000 ago. Dr Sergio Castellano, one of the co-authors of the paper in Nature, suggests that as the study has now shown by genetic evidence that the histories of Neanderthals and Homo sapiens are closely intertwined it is better to describe the Neanderthals and modern humans as 2 different human groups, an archaic and a modern, and not different species.

The Siberian woman has shown that Neanderthals and modern humans could have met and interbred outside Africa as early as 120,000 BP, as it is now believed that modern humans and Neanderthals were both present at the same time in the region around the Persian Gulf, as well as in the area now occupied by Cyprus, Egypt, Israel, Lebanon, Syria and Turkey.

Waves of human migration

The Siberian woman’s DNA was analysed by Kuhlwilm et al. and portions of her DNA were identified as matching sequences from people who are presently living in Africa.

Kuhlwilm et al. also analysed the remains of a Denisovan, another type of archaic hominin that was found in the same cave, and the remains of 2 other Neanderthals from other caves, 1 in Croatia and 1 in Spain, and no modern human DNA was found in any of the latter 3 individuals. It was concluded that it was likely a population of Neanderthals that had  migrated from Europe through the Near East where mating with modern humans took place, after which they continued on into the Altai Mountains, where at that time, 125,000 BP, the climate was much milder than at present.

The researchers believe that the modern humans who were present in the Near East at this early time eventually died out without contributing to the genome of the Homo sapiens of the present. It is nevertheless believed that some living people from Asia and Oceania have more Neanderthal DNA as a result of a second episode of admixture that may have occurred with Neanderthals.

This new evidence doesn’t support the widely held belief that modern humans left Africa for the first time about 60,000 BP [or 70,000 BP]. Rather, it seems 1 or more other groups left Africa 10s of thousands of years earlier, and it appears at least some of them were mating with Neanderthals along the way. It has been said by Prof. Slatkin of the University of California, Berkeley, the results of this new study are important as they demonstrate how complex the relationships between modern humans and Neanderthals were. He suggests it will be interesting if further research shows that modern humans were interbreeding with Neanderthals outside Asia. It would also be interesting if future research finds that modern humans were interbreeding with other archaic humans that were present at the time.

Sources & Further reading

Viegas, Jennifer, 18 Feb 2016, Neanderthals had human DND too, suggesting Homo sapiens left Africa earlier than thought, Discovery news