Their somewhat unwelcome snippet of information came to light when Michael Hofreiter, an evolutionary biologist at the Max Planck Institute in Germany, managed to extract enough DNA from two Neanderthal skulls to determine their colouring and skin type.

"Our calculations suggest that at least 1% of Neanderthals had red hair, " said Hofreiter. "They would have had lighter hair all over their bodies, like today's Irish redheaded people."

The DNA samples also pointed towards the Neanderthals having light, freckled skin. In fact, they couldn't look more classically Irish.

It's certainly a far cry from the archetypal swarthy, beetlebrowed image of Neanderthals that has been circulated for decades from the study of fossil bones.

Until now, the understanding of Neanderthals was limited mostly to bone structure and artifacts. Scientists knew they used stone tools, were stockier than we are and had prominent brow ridges. However, it is only in recent years that genetics has advanced enough to read the degraded DNA lodged in Neanderthal bone cells.

The study provides another link between humans and Neanderthals, following on from research published earlier this year that suggests that Neanderthals had a version of a gene that appears to be involved in speech. And the scientists don't intend to stop there.

The group from the Max Planck Institute are hoping to get enough information finally to put to rest the fiercelyfought debate about whether the Neanderthals could be considered a member of the human family, and may have bred with our ancestors. The topic has created a split in scientific circles, with one group arguing that the Neanderthals hardly had two brain cells to rub together and the other insisting that Neanderthals were rather smart, actually.

"We are building an image of these Neanderthal people . . . their physical aspects, cognitive abilities, metabolism, immunity . . . the range is enormous, " said Carles LaluezaFox, a co-author of the report from Barcelona.