Eye-ai-ai

A new theory posits that it was the Neanderthals' big eyes that led to their extinction. The thought is that when they left Africa and ended up in Europe, where the nights were longer and darker, they evolved larger eyes and the correspondingly larger vision-processing part of the brain. That, in turn, caused the cognitive areas to shrink: http://www.bbc.co.uk/news/science-environment-21759233