The WHR or waist-to-hip ratio in females has stood the test of time as a factor for desirability in almost all cultures across the globe. The preference for a low WHR has been prevalent even in the most ancient of civilisations. Even today, there are people who find “hourglass” or “pear” body shapes as more sexually desirable than other body types.
Note: WHR is the ratio of the dimensions of your waist at its narrowest, and your hips/posterior measured at their widest.
This study asked hetero men and women which body shape among females they found attractive. The answer was interesting insofar as while they diverged on other details, they seemed to agree on the low WHR factor. Since straight females were included in the study as well, it sort of forecloses the possibility of the factor being purely sexually attractive; on the contrary there is some instinct in all humans that resonates with this preference.
A low WHR has always been an indicator for fertility: and it is also an indicator for better vascular health, while a high WHR has been correlated with increased risks of auto-immune disease and even cancer.
The standards for men and women are of course, different: with females it’s a low WHR while with men it is minimising belly fat.
In women the low WHR ratio is a result of hormonal balance. This said balance promotes overall health as well, which is the other theory; that is, we find the low WHR attractive because it is a marker of overall health.
This study along with others shows how this same hormonal balance also creates certain vocal characteristics and a certain smell, both of which again, are markers for better health.
The attraction theory also states how as a low WHR is indicative of better health, the instinct that kicks in, in potential mates is that the individual will produce healthy offspring; which makes them attractive sexually.
It is an evolutionary instinct as desirable females (in the sense of evolution exclusively) are healthier, more robust and fertile.
However this correlation, between low WHR and fertility has been debated: women who are healthier in general tend to be more fertile and/or fecund.
In the largest cross-cultural study of its kind, Piotr Sorokowski and co-researchers at the University of Wroclaw in Poland, measured the WHR of nearly 1,000 women and plotted them against reproductive history.
The controls of the experiment were BMI and age (13-95).
The results were thus: While, unsurprisingly BMI and age correlated with no of offspring, there was also a linear relationship between a WHR and the number of offspring. (Lesser the WHR, lesser the number of children)
This turns traditional theories topsy-turvy.
But there is a certain nuance one would ignore at face-value.
A more appropriate way of interpreting this would be, a low WHR besides showing future fecundity, also reflects a reproductive past: that is it signals to a potential mate that the individual’s fertile days are ahead and not in the past.
Another way to look at it would be that, female subjects transition from a low to high WHR after giving birth to children.
That is, the low WHR was a way of detecting the fertility potential of a female.
So, the conclusion does not really contradict the attraction theory, but actually extrapolates it: that is, females with a low WHR besides being in a state of better health also indicates the fact that the individual hasn’t had many children/ has her most fertile days ahead of her. Hence the preference evolution-wise.
Of course, this cannot be considered in isolation; societal factors come into play as well. But this establishes the fact that there IS a correlation after all.