However, evolutionary biologist Clive Finlayson at the Gibraltar Museum and his colleagues recently found that clusters of Neanderthals might have lasted until as late as 24, 000 years ago.

"All this paper shows is that Neanderthals lived somewhere in the Caucasus about 40,000 years ago," said Finlayson, who did not take part in this new study. "Doesn't mean they went extinct then."

His main rivals, Rudy Giuliani, Mitt Romney and Fred Thompson, emphasise how tough they will be on terrorists but say as little as possible about Iraq.