Recent study showed that women who have to rely on their own resources, such as going out to work, to support themselves and their families usually don't have 0.7 or less the waist to hip ratio. They have more cylindrical bodies.

Study revealed that hormones that make women physically stronger, more competitive, better able to withstand stress, also move fat from the hips to the waist.

Elizabeth Cashdan, an anthropologist at the University of Utah in Salt Lake City, USA studied women's waist to hip ratios in 33 non-Western and 4 European populations. She found that the average was above 0.8.

But previous studies have shown that the more curvy female shape with a waist to hip ratio of 0.7 or less is closely linked to higher fertility and lower rates of chronic diseases.

Some studies have also shown that when selecting a female mate, men tend to favour the 0.7 or lower waist to hip ratio, which makes sense to those studying evolutionary biology because a healthy and fertile female mate increases the chances of the man's genes being passed onto a new generation.

Cashdan said: "The androgenic effects -- stamina, initiative, risk-proneness, assertiveness, dominance -- should be particularly useful where a woman must depend on her own resources to support herself and her family."

Cashdan concluded that perhaps waist to hip ratio is a useful signal for men when choosing a mate, but the extent to which they go for a higher or lower ratio will depend on the "degree to which they want their mates to be strong, tough, economically successful and politically competitive."