From Kim Kardashian to Beyonce, many of the most beautiful women in the world are known for their hourglass figures.
But why do men find this body shape so attractive?
Dr Jeanne Bovet, an evolutionary biologist at Stony Brook University has explored this age-old question in a new study, published in Frontiers in Psychology.
In the study, Dr Bovet analysed previous research about the traits linked to a woman’s waist-to-hip ratio (WHR), and why these women may be perceived as better mates.
Women with a low WHR have an hourglass figure, while those with high WHR have a more straight figure.
The first traits identified were relatively basic.
Dr Bovet said: “Sex, age, pregnancy and number of children can all be reliably inferred.”
As women age and have children, their WHR usually increases, which could infer to men that they're less appealing mates, according to Dr Bovet.
She explained: “WHR tracks reproduction potential, which is null in prepubertal, pregnant and postmenopausal women; peaks in the twenties; and is unreliable in women with many children or none.”
However, a rather surprising trait linked to WHR that Dr Bovet identified was baby fat.
She explained: “Fat on the hips, thighs and buttocks is special in women. Even with restricted food intake, the body avoids burning it.
“But in late pregnancy and lactation, the same fat becomes freely available as the main source of long-chain polyunsaturated fatty acids critical for early brain development.
“In keeping with this, one study has shown that women with lower WHRs and their children have significantly higher cognitive test scores.”
Dr Bovet suggests that there may be several other traits linked to WHR, including an indicator of sexual behaviour or a warning of abdominal parasites, although these remain untested.
She added: “Whether rapid cultural evolution and reproductive technologies will relax men’s preferences for a narrow female WHR – or if ‘runaway selection’ for once-useful traits, and pursuit of gene-propagating ‘sexy daughters’, will intensify them – is a story that will unfold deep into the future.”
