Sunday, January 16, 2011

Neanderthals' faces weren't adaptations to cold

Neanderthals, bless 'em, were never going to win any beauty contests. Now scans of their skulls show their robust faces, with wide noses and prominent cheekbones, weren't even adaptations to the cold.

The Neanderthal face shape was thought to be a result of the growth of large sinuses, which warm inhaled air. However, modern humans who live in the Arctic and other mammals that live in the cold don't have large sinuses.

"Their sinuses are smaller than average, probably because air warming happens only in the nasal cavity which has grown bigger to leave less space for the sinuses," says Todd Rae from Roehampton University in London.

To find out how big – or small – Neanderthal sinuses really were, Rae and colleagues analysed data from X-rays and 3D CT scans of Neanderthal skulls.
Large face, large sinuses

When the team compared these scans with those of the skulls of Homo sapiens from temperate regions, they found Neanderthals' sinuses were bigger, but only because they had bigger faces; the two species' sinuses had the same relative size relationship.

This suggests that Neanderthal faces were not shaped to deal with extreme cold, says Rae's team. In the image above, the skull on the right is a Neanderthal, that on the left is Homo sapiens.

Rae says we can now dismiss the cold adaptation idea. "This allows us to think about Neanderthals and their lives in new ways."

John Stewart from Bournemouth University in Poole, UK, says the work dispels "what was essentially a 'Just-So' story". He believes the results fit with his own idea that the short Neanderthal legs were not a cold adaptation but rather reflect a forest life where short limbs helped to navigate through the undergrowth.

Journal reference: Journal of Human Evolution, DOI: 10.1016/j.jhevol.2010.10.003

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