The findings, published...in the journal Proceedings of the Royal Society B, suggest that Neanderthals developed massive visual regions in their brains to compensate for Europe's low light levels. That, however, reduced the brain space available for social cognition.
"We have a social brain, whereas Neanderthals appear to have a visual brain," said Clive Gamble, an archaeologist at the University of Southampton, who was not involved in the study.
As a result, the extinct hominids had smaller social and trading networks to rely on when conditions got tough. That may have caused Neanderthals to die off around 35,000 years ago.