Cometh the hourglass

September 02, 2019

Male turkeys famously will attempt to mate with a head on a stick. In fact, gobblers prize a snug snood over the whole hen. How far then can a man's ideal sexual partner be stripped?

As hopeless romantics we practice a more esoteric eroticism. Nevertheless, there are patterns.

Waist-to-hip ratio (WHR) is a strong predictor of women's physical attractiveness. The 'ideal' value varies, but it is always low relative to men's or the average female WHR. Writing in Frontiers in Psychology, one woman asks: why?


Over the last 25 years, research on WHR as an indicator of women's attractiveness has flourished. But its link to female mate value - i.e. how WHR preferences influence a man's reproductive success - is rarely expressed beyond euphemisms like "health" and "fertility" of low-WHR women. (Note: a low or 'narrow' WHR means hips relatively larger than the waist.)

It is a classic example of "just-so storytelling" in evolutionary explanations of human behavior, says Dr. Jeanne Bovet of Stony Brook University (SUNY).

After combing the literature, Bovet defined specific traits that could link WHR with mate value, to be subjected to empirical scrutiny. She asked: can a man select this trait in a mate, based on her WHR? And will he have more and higher-quality descendants as a consequence?

Sex, age, pregnancy and parity

Most of the mate value-related information provided by WHR is relatively basic, suggests Bovet: "Sex, age, pregnancy and number of children can all be reliably inferred".

WHR is high in children and men. In women though, WHR drops around the onset of puberty until early adulthood, then rises again with age and number of children. Temporary increases in waist size are the unique reliable visual cue of current pregnancy. As such, 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.

Baby fat

One surprising WHR-related trait enjoys particularly compelling evidence of mate value, however.

That a wider pelvis facilitates delivery of big-brained offspring is a widely accepted idea. Perhaps it was the first to enter your mind in relation to WHR.

Alas though, the mechanical demands of bipedal locomotion strictly limit pelvis size - so that most WHR variance is in fact due to fat storage on the hips and waist. But it appears that the distribution of this fat is likewise a major gatekeeper of brain development.

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. Abdominal fat interferes with this: it inhibits production of the enzyme Δ-5 desaturase, required for synthesis of the fatty acids.

In keeping with this, one study has shown that women with lower WHRs and their children have significantly higher cognitive test scores - and IQ is negatively correlated with birth order, following the loss of gluteofemoral fat with each child.

A moving target

Evolution of preferences for a low WHR in female mates likely involved a number of these traits. Still more - including WHR as a hormone-driven indicator of sexual and maternal behavior, or a warning of abdominal parasites - remain untested.

WHR's correlation with attractiveness might even prove to be an artifact, with some related physical characteristic like hip size alone, or waist/stature ratio, the real object of men's desires.

But 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.
Please link to the original research article in your reporting:

Corresponding author: Dr. Jeanne Bovet,

Frontiers is an award-winning Open Science platform and leading open-access scholarly publisher. Our mission is to make high-quality, peer-reviewed research articles rapidly and freely available to everybody in the world, thereby accelerating scientific and technological innovation, societal progress and economic growth. Frontiers received the 2014 ALPSP Gold Award for Innovation in Publishing. For more information, visit and follow @Frontiersin on Twitter.


Related Pregnancy Articles from Brightsurf:

COVID-19 has a prolonged effect for many during pregnancy
Symptoms for pregnant women with COVID-19 can be prolonged, lasting two months or longer for a quarter of the women who participated in a national study led by UC San Francisco and UCLA.

Relaxed through pregnancy
A group of researchers from Charité - Universitätsmedizin Berlin have been able to show that maternal psychological wellbeing during pregnancy has a positive effect on newborn infants.

Trajectories of antidepressant medication use during pregnancy
In an analysis of women who started pregnancy when taking antidepressant medications, investigators identified three trajectories of antidepressant dispensing during pregnancy: more than half stopped their treatment, a quarter maintained their treatment throughout pregnancy, and one-fifth discontinued it for a minimum of three months and then resumed it during the postpartum period.

Are women using e-cigarettes during preconception and/or pregnancy?
A new study of 1,365 racially/ethnically diverse, low-income pregnant women found that 4% reported e-cigarette use.

A better pregnancy test for whales
To determine whale pregnancy, researchers have relied on visual cues or hormone tests of blubber collected via darts, but the results were often inconclusive.

Cannabis use during pregnancy
The large health care system Kaiser Permanente Northern California provides universal screening for prenatal cannabis use in women during pregnancy by self-report and urine toxicology testing.

Questions and answers about cannabis use during pregnancy
A new study shows that women have many medical questions about the use of cannabis both before and during pregnancy, and during the postpartum period while breastfeeding.

The effect of taking antidepressants during pregnancy
Exposure to antidepressants during pregnancy and the first weeks of life can alter sensory processing well into adulthood, according to research in mice recently published in eNeuro.

Is ivermectin safe during pregnancy?
Is it safe to give ivermectin to pregnant women? To answer this question, researchers from the Barcelona Institute for Global Health (ISGlobal), an institution supported by 'la Caixa,' conducted a systematic review and meta-analysis of studies that reported cases of accidental exposure to the drug among pregnant women.

Going to sleep on your back in late pregnancy
This study looked at whether going to sleep on your back in the third trimester of pregnancy was associated with average lower birth weights.

Read More: Pregnancy News and Pregnancy Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to