terça-feira, 12 de fevereiro de 2008

DNA says Neanderthals were redheads

Agençe France-Presse
26 October 2007

Some of our prehistoric Neanderthal relatives probably had red hair and fair complexions, much like modern-day people of Celtic origin.

The finding comes from the first such analysis of DNA evidence taken from Neanderthal fossils recovered from El Sidron in northern Spain and Monti Lessini, Italy.

An analysis of the DNA revealed the ancient hominids carried a mutation in the MC1R gene that codes for a protein involved in the production of melanin – a substance that gives skin its colour and also protects it against ultraviolet light.

Ginger mutation
In modern humans, primarily of European descent, mutations in the MC1R gene are thought to be responsible for red hair and pale skin by dampening the activity of the protein.

The mutation observed in the Neanderthal genes was different from the one documented in humans, but when scientists inserted the Neanderthal gene into cells in a test tube, it seemed to have the same effect on melatonin production as the modern human genes, according to the study published in the U.S. journal Science.

The genetic analysis doesn't seal the deal, but since the fossil record of Neanderthals does not include any samples of skin or hair, it is the best guide available, said Michael Hofreiter, a palaeogeneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
Hofreiter said the number of red-headed Neanderthals was probably pretty small, possibly just one per cent of the population and might have popped up in any part of Europe or Asia that the ancient hominids had settled.

Vitamin D link

The news did not come as a surprise to one leading scholar of Neanderthal evolution and biology.
"The stereotype of primitive peoples is that they are dark skinned, but some palaeontologists have been speculating for 20 years that some Neanderthals must have been pale skinned because they lived in northern Europe," said Erik Trinkaus, a professor of anthropology at Washington University in St Louis, Missouri. "Light skin is adaptive at higher altitudes because it allows more UVB radiation to penetrate the skin and that promotes Vitamin D synthesis."

Neanderthals, whose ancestors diverged from that of modern humans about 300,000 years ago, colonised Europe and parts of Asia, dominating Europe until about 30,000 years ago.

The study suggests that the genes that confer pale skin and red hair evolved separately in humans and our closest extinct relatives.

Source: http://www.cosmosmagazine.com/node/1675

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