Neanderthal brains were adapted to allow them to see better and maintain larger bodies, which left less room for higher level thinking needed to socialise, eventually leading to their extinction, scientists claim.

According to new research by the University of Oxford and the Natural History Museum, London, although Neanderthals\' brains were similar in size to their contemporary modern human counterparts, fresh analysis of fossil data suggests that their brain structure was rather different.

Results showed that larger areas of the Neanderthal brain, compared to the modern human brain, were given over to vision and movement and this left less room for the higher level thinking required to form large social groups.

Looking at data from 27,000 75,000-year-old fossils, mostly from Europe and the Near East, researchers compared the skulls of 32 anatomically modern humans and 13 Neanderthals to examine brain size and organisation.

In a subset of these fossils, they found that Neanderthalshad significantly larger eye sockets, and therefore eyes, than modern humans.

The researchers calculated the standard size of fossil brains for body mass and visual processing requirements. Once the differences in body and visual system size were taken into account, the researchers were able to compare how much of the brain was left over for other cognitive functions.

Previous research by the Oxford scientists shows that modern humans living at higher latitudes evolved bigger vision areas in the brain to cope with the low light levels. This latest study builds on that research, suggesting that Neanderthals probably had larger eyes than contemporary humans because they evolved in Europe, whereas contemporary humans had only recently emerged from lower latitude Africa.

"Since Neanderthals evolved at higher latitudes and also have bigger bodies than modern humans, more of the Neanderthal brain would have been dedicated to vision and body control, leaving less brain to deal with other functions like social

networking," said lead author Eiluned Pearce from the Institute of Cognitive and Evolutionary Anthropology at the University of Oxford.

"Smaller social groups might have made Neanderthals less able to cope with the difficulties of their harsh Eurasian environments because they would have had fewer friends to help them out in times of need," Pearce said.

"Overall, differences in brain organisation and social cognition may go a long way towards explaining why Neanderthals went extinct whereas modern humans survived," Pearce said in a statement. The study was published in the journal, Proceedings of the Royal Society B.