Having a large bust and long pins are deemed by western culture as the epitome of femininity, but when choosing a mother for their children, men look for brains first.

Prof David Bainbridge said that intelligence is by far the most attractive quality for men looking for a long-term partner because it shows his chosen partner is likely to be a responsible parent.

It also suggests she was brought up by intelligent parents and was well looked after in childhood.

Prof Bainbridge said men do not care how large a woman's breasts are as long as they are symmetrical. With legs, it only matters that they are straight - bent, uneven legs suggest a developmental illness, such as rickets.

"Breast size doesn't matter," he told the Hay Festival. "Large breasts are more likely to be asymmetric and men are more attracted to symmetry. And they look older more quickly, and men value youth. And men are not looking for long legs. Straight legs are a sign of genetic health, so that is something that is more attractive, but surveys have shown most men prefer regular length.

"The main thing that men are looking for is intelligence. Surveys have shown time and time again that this is the first thing that men look for.

"It shows that she will be able to look after his children and that her parents were probably intelligent, suggesting that she was brought up well."

Men also look for symmetry in facial and bodily features which suggests 'stable' genes and youthful partners.

Studies have shown that men who are four to five years older than their partners are more successful.

But men do like women to be curvaceous with voluptuous thighs and bottoms and a waist much slimmer than their hips.

Carrying more weight on the thighs and the bottom suggests a woman has stored enough fat during puberty to provide for a growing baby.

The development of babies' brains relies on fat stripped from mothers' thighs and bottoms, especially during breastfeeding, and fat supplies may affect a child's intelligence and chances of survival.

"It is why such fat is hard to shift because the body saves it.

Mammals' and primates' bodies have about five to 10 per cent of fat, but in human women that rises to 30 per cent, similar to the levels seen in hibernating bears or whales living in Arctic seas.

Women have traded muscle for fat, so are about a third as strong.

London Daily Telegraph