A new study links the demise of Neanderthals to the size of their eyes, which were larger than those of modern-day man.
The larger eyes meant a larger part of their brain was devoted to good vision during the long, dark nights of the period, which left little room for higher-level thinking processes which finally led to their extinction, scientists claim.
Although their brains were similar in size to those of modern-day man, according to new analysis of fossil data by the University of Oxford and the Natural History Museum in London, their brain structure was markedly different. The cognitive functions that made for survival of Homo Sapiens during the ice age by creating warmer clothes and forming larger social groups had less space in the Neanderthals' brain.
Lead author Eiluned Pearce from the Institute of Cognitive and Evolutionary Anthropology at the University of Oxford said since Neanderhals evolved at higher latitudes, and also had 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. (See: Neanderthal brains focussed on vision and movement leaving less room for social networking).
Pearce added, 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.
Neanderthals, a closely related species of human, lived in Europe from around 250,000 years ago, briefly coexisting and interacting with our species until they went extinct about 28,000 years ago, partly due to an ice age.
The research team explored the idea that the ancestors of Neanderthals left Africa and had to adapt to the longer, darker nights and murkier days of Europe, that led to larger eyes and a much larger visual processing area at the backs of their brains.
Humans that stayed put in Africa, however, continued to enjoy bright and beautiful days and therefore had no need for such an adaption. Also our ancestors, evolved their frontal lobes, associated with higher-level thinking, before spreading across the globe.
Pearce compared the skulls of 32 Homo sapiens and 13 Neanderthals and found that Neanderthals had significantly larger eye sockets - by an average of 6mm from top to bottom.
She added, they were very, very smart, but not quite in the same league as Homo Sapiens and that difference might have been enough to tip the balance when things were beginning to get tough at the end of the last ice age.