The Fate Of Neanderthal Genes

The Neanderthals disappeared about 30,000 years ago, but little pieces of them live on in the form of DNA sequences scattered through the modern human genome. A new study by geneticists at the University of California, Davis, shows why these traces of our closest relatives are slowly being removed by natural selection.

Modern humans and Neanderthals interbred tens of thousands of years ago. New work shows how the difference in  population size has led to genes that survived in Neanderthals being removed from the modern human genome 

[Credit: WikiCommons/DrMikeBaxter]

“On average, there has been weak but widespread selection against Neanderthal genes,” said Graham Coop, professor in the UC Davis Department of Evolution and Ecology and Center for Population Biology, and senior author on a paper describing the work published in the journal PLOS Genetics. That selection seems to be a consequence of a small population of Neanderthals mixing with a much larger population of modern humans.

Neanderthals split from our African ancestors over half a million years ago, and lived in Europe and Central Asia until a few tens of thousands of years ago. Archaeological discoveries have shown that they had quite a sophisticated culture, Coop said. Thanks to DNA samples retrieved from a number of fossils, we have enough data on the Neanderthal genome to identify their genes among ours.

When modern humans left Africa about 50,000 to 80,000 years ago and spread through Europe and Asia, they interbred with Neanderthals. The first hybrid offspring would have been, on average, a 50-50 mix of modern human and Neanderthal genes, and could then have themselves bred with modern humans, Neanderthals or other hybrids.

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