BEAUTY is said to be skin-deep, and women have always complained of being judged solely on their looks when they have so much more to offer. But in future it seems they may have to bite their tongues, because research has found that the female of the species is just as shallow when it comes to choosing a partner.

Scientists at the University of Bristol have found women are genetically programmed to find beauty more desirable than brains. Animal instinct drives them to search for good-looking husbands in order to ensure their own sons will be handsome. Behind this desire is the rationale that good-looking male offspring are more likely to find a mate and have children of their own.

For many women, the news that they are attracted to attractiveness will come as no surprise. And they will now be able to relinquish any feelings of guilt about their desires because they are helping to ensure the survival of the species.

Novelist Jilly Cooper is not in the least ashamed of her preference for handsome men. "I have a terrible weakness for beauty. With age, I prefer macho beauties. Strapping, rugger hunks."

But while most women will admit they cannot help gravitating in the direction of a pert bottom or square jaw, many may be a little surprised to learn that they naturally prefer brawn to brains.

Cooper says: "There's this myth

that women prefer intellectuals to beauties, but I think that's complete garbage.

"The only people who don't like beautiful men are other men. They get very cross and twitchy because there is a new stag in the forest.

"I don't like goaty academics at all. They always have awful beards which they get taramasalata stuck in.

"But what I really can't bear is that they think women will like them because they're so brainy, so they just leap on everybody in sight. They think that anybody they impregnate is lucky to get their genius genes."

If Cooper and the researchers at Bristol are correct, and women do prefer looks to brains, then Joey the character in the hit comedy Friends would qualify as the ideal man.

The ultimate himbo, Joey is utterly beautiful with his dark hair, soulful brown eyes and muscly body. And he is also completely thick, the kind of man whose only chat up line is "How you doin'?", delivered in a sexy New York drawl.

Unaware that he is perfect as he is, Joey does sometimes try to boost his brain-power. Luckily it always backfires. His loo roll is printed with an improving word for each day - but he never has any idea of how to use the new vocabulary.

Elaine Wright, director of Ladies Excuse Me, a dating agency where women do the choosing, confirms that women do go for eye candy over IQ.

She says: "When the ladies say they are not interested in looks, they always choose the better looking men. It is a myth that women are only interested in personality.

"If there was the choice between a man who was good looking but not incredibly intelligent, or bright but unattractive, most ladies would probably go for the looks."

Relationship counsellor Julia Cole agrees: "Women make instant judgements sometimes on whether they are attracted to a man or not based entirely on the way they look.

"They are just as attracted by a handsome face and a pert bum as men are to other parts of women."

But although there is general agreement that women are aesthetically critical of men, the big question is - what exactly are they looking for?

Biologists have gathered evidence from species as diverse as zebra finches, elk and human beings that creatures appraise the worthiness of a potential mate by looking for at least one benchmark of beauty - symmetry.

Scientists at the University of Mexico have found that men with symmetrical faces - but not women - have more sexual partners, begin sex earlier in life, and engage more in sexual infidelity.

Certainly, it is obvious that beauty is not just in the eye of the beholder. There are certain men, like Brad Pitt and George Clooney, who are almost universally considered to be attractive by the opposite sex.

Wright says: "Some men on our books have no end of success. Facially, they tend to be traditionally handsome with some sort of character that makes them stand out from the crowd."

But aesthetically challenged men should not despair. If women only ever chose the best looking men to father their children, there would be far more childless men around.

A Bristol University study found that those who spend too much time singling out the best mate may run into trouble. The study concluded: "A choosy female might take longer to find a mate and hence leave fewer surviving offspring, either because she is in poorer condition at reproduction or because young produced late have lower survival prospects."

And Cole warns: "In prehistoric times, you only lived to 25, so physical appearance was probably a good way to chose a mate. This might have favoured women giving birth to strong children.

"But these days, after children, you will have, say, 40 years with someone, during which time you will both age and develop wrinkles and paunches and middle-age spreads. It is only personality and character that will keep you together.