Neanderthal breeding idea doubted

By | August 14, 2012

Similarities between the DNA of modern people and Neanderthals are more likely to have arisen from shared ancestry than interbreeding, a study reports.

That is according to research carried out at the University of Cambridge and published this week in PNAS journal.

Previously, it had been suggested that shared parts of the genomes of these two populations were the result of interbreeding.

However, the newly published research proposes a different explanation.

The origin of modern humans is a hotly debated topic; four main theories have arisen to describe the evolution of Homo sapiens.

All argue for an African origin, but an important distinction in these competing theories is whether or not interbreeding – or “hybridisation” – occurred between Homo sapiens and other members of the genus Homo.

In the current study, Cambridge evolutionary biologists Dr Anders Eriksson and Dr Andrea Manica used computer simulations to reassess the strength of evidence supporting hybridisation events.

They argue that the amount of DNA shared between modern Eurasian humans and Neanderthals – estimated at between 1-4% – can be explained if both arose from a geographically isolated population, most likely in North Africa, which shared a common ancestor around 300-350 thousand years ago.

When modern humans expanded out of Africa, around 60-70,000 years ago, they took that genetic similarity with them.

By contrast, previous ancient DNA studies of Neanderthal remains have shown that their genomes harbour genetic signatures – polymorphisms – that are also seen in the genomes of modern Europeans, East Asians and Oceanians (from Papua New Guinea) but not in modern African populations.

The findings challenged previously held views – based on several lines of evidence – that modern humans had replaced the Neanderthals with little or no gene flow occurring between the two groups.

via BBC News – Neanderthal breeding idea doubted.

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