Blue eyes are now more common in Britain than any other colour, scientists have revealed. And it's likely it's because Brits find the colour more sexually alluring than brown or green eyes.

The Blue Eyes Project has found that although all eyes in Britain were once brown, they are now 48% blue, 30% green and just 22% brown.

Although there are no direct physical advantages to having blue eyes, such as better eyesight, the overwhelming change of eye colour from brown to blue has been a cross-Europe phenomenon.

Blue eyes are like the peacock\'s tail. It doesn\'t confer any evolutionary advantage for the peacock except that it gets him more mates. - Alistair Moffat, ScotlandsDNA

Alistair Moffat, managing director of ScotlandsDNA, which carried out the research, told The Times: "A lot of people think blue eyes are much rarer than they are."

He suggested one reason for their dominance is that blue eyes are recognised as being more attractive and so people seek out those with blue eyes as potential mates. Moffat said: "It may be that all blue eyes are like the peacock's tail. It doesn't confer any evolutionary advantage for the peacock, except that it gets him more mates."

The study mapped eye colour across the UK and Ireland and found that Scottish and Irish people are more likely to have blue eyes than in other parts of the UK, particularly the south.

Just over a third (35%) of the population of south-west England and 41% in east England have blue eyes, compared to 57% in southeast Scotland.

Beauty in a genetic mutation

Blue eyes are the result of a variant in the HERC2 gene, which, when it mutates, switches off the supply of brown-eye forming melanin, researchers say. Green eyes are also a result of this change, because they arise from a combination of the blue variant with brown.

The first gene mutation resulting in blue eyes is understood to have occurred in the Baltic region around 10,000 years ago.

Hans Eiberg, a scientist from the Univesity of Copenhagen, who made the discovery said: "Blue eyes are more attractive to potential partners than brown. One mutation 10,000 years ago has today resulted in almost 200 million pairs of blue eyes, and people with blue eyes have more blue-eyed children.

"Blue eyes are seen as powerful. I have recently been in China and in the temples there all the gods are painted with blue eyes, but everyone else has dark eyes."

Eiberg continues: "There is something attractive about blue eyes, maybe because they used to be so rare."

Alistair Moffat has another theory: "Because of the way blue eyes deal with light, they appear to have inherited a natural sparkle. Dark coloured eyes, the various shades of brown, are able to absorb longer and shorter wavelengths and therefore they appear not to reflect it. They don't seem to sparkle."

But some believe blue eyes could one day become less desirable as they are seen as 'the norm' in Britain. Dr Jim Wilson, chief scientific officer at the Blue Eyes Project said: "If rarity makes a feature more attractive then it could be that this process is reversed. If blue eyes pre-dominate in Europe then brown eyes might become more desirable."