October 6, 2012

Awkward Family Reunions: Humans And Neandertals

New research from Harvard and the Max Planck Institute suggests why the Neandertals are more closely related to peoples from outside Africa with the conclusion that when modern humans emerged from that continent, they were not shy about interbreeding with other hominids. These are, the scientists conclude, the ancestors of people across Europe and Asia.

The Neandertal genome was sequenced in 2010 and indicates that modern Europeans share between 1 and 4 per cent of their genes with Neandertals. It also revealed that people outside of Africa share slightly more genetic variants with Neandertals than Africans do.

One scenario that could explain this observation is that modern humans mixed with Neandertals when they came out of Africa, writes Damien Gayle for Mail Online.

An alternative, but more complex, scenario is that African populations ancestral to both Neandertals and modern humans remained subdivided over a few hundred thousand years and that those more related to Neandertals subsequently left Africa.

Research has found that modern humans begin to appear in the African fossil record about 200,000 years ago. Neanderthals appear in the European fossil record about 230,000 years ago and disappear about 30,000 years ago. They lived in Europe and western Asia with a range that extended as far east as Siberia and as far south as the middle East.

Evidence both for and against interbreeding have been put forth based on the analysis of modern human DNA. Dr. Sriram Sankararaman, of Harvard Medical School’s genetics department, and colleagues measured the length of DNA pieces in the genomes of Europeans that are similar to Neanderthals.

Based on their findings, published in the open-access journal PLoS Genetics, the team estimate that Neanderthals and modern humans last exchanged genes between 37,000 and 86,000 years ago, well after modern humans appeared outside Africa but potentially before they started spreading across Eurasia.

This suggests that Neandertals (or their close relatives) had children with the direct ancestors of present-day people outside Africa.

Image Credit: Don Purcell / Shutterstock

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