Shutterstock/Used by Permission
Source: Shutterstock/Used by Permission

The beauty industry is big business.  And whether we are talking about plastic surgery, makeup, or hair products, the goal is always to help women appear to be younger.

You do not see 25-year-old women trying to look 60, but you do see older women trying their best to look 25 again.  In fact, the only females who try to make themselves look older are pre-teens who have not yet reached their prime of fertility.  When it comes to female beauty, the real buttons that are getting pushed in male brains are the ones that signal that a woman is of the right age and in good enough health to conceive and successfully bear children. 

In our prehistoric past, the genes of men who preferred 60-year-old women to 20-year-old women were trampled in the Darwinian dust.

Thus, it is no secret that when it comes to physical beauty, women are held to higher standards than are men, and cross-culturally, women are judged by their physical attractiveness to an extent than men cannot even imagine.  I am not suggesting that this is desirable or fair, but all of the evidence indicates that the phenomenon is real.

Many of the standards by which female beauty is evaluated are well known: well-formed breasts, a symmetrical face, slender shapely legs, and lustrous hair are obvious qualities that enhance a woman’s beauty.  However there are a variety of more subtle markers of beauty that also increase ratings of female attractiveness.  Evolutionary psychologists propose that these characteristics are attractive to men because they are hard to fake.  In other words, they are honest signals of a woman’s age and reproductive value.

Just what are some of these underappreciated cues to female fertility?

A Woman’s Voice is a Marker of Attractiveness

Over 40 years ago, social psychologists discovered that the physical attractiveness of a woman could be judged fairly accurately by way of a telephone conversation when no visual cues were available.  At the time, this was a matter of great curiosity and there were a number of theories proposed that attempted to explain it.  For example, one of the more popular ideas was that attractive women simply had more lifetime experience of people paying attention to them and interacting with them socially, giving them more opportunities to hone social skills that might translate into attractiveness during a phone call.

However, it has now been convincingly demonstrated that the attractiveness of women’s voices are in fact positively correlated with the actual attractiveness of their faces.  In experiments of this type, men independently judge the attractiveness of a group of female faces, and then separately evaluate the attractiveness of voices from the same sample of women.  The men making the judgments do not know which voices go with which faces, but if they rate a woman’s voice as attractive, they tend to rate the corresponding face as attractive as well.  In general, a higher pitched female voice is judged to be younger, and hence, more attractive.

I should also point out that male facial attractiveness can be predicted from a voice, with the curious addition that men who do not articulate clearly in their speech tend to be judged as more masculine.

Limbal Rings

A “limbal ring” is the dark ring that appears around the iris (i.e., the colored part) of the eye.  A wide dark limbal ring is an honest signal of youth and health, as the limbal ring fades and narrows as people age. Therefore, it is not surprising to discover that thick limbal rings significantly enhance the judgments of the attractiveness of eyes

One can now purchase contact lenses that enhance the presentation of limbal rings.

Lumbar Curvature

Shutterstock/Used by Permission
Source: Shutterstock/Used by Permission

Fairly recently, studies have demonstrated that lumbar curvature also appears to be a universal standard of female beauty.

The evolutionary origins of lumbar curvature as a beauty signal come from the problems faced by bipedal human females when they become pregnant.  If their spines were designed like male spines, the muscle fatigue and back pain that they faced would have been considerable.  Consequently, the structure of the female spine has shifted the center of gravity backward, decreasing bodily stress during pregnancy, leading to better foraging abilities and other adaptive advantages.  Studies have confirmed that males judge female bodies that display an optimal amount of lumbar curvature to be the most attractive.

The backless dresses on the movie stars on the red carpet are a not-so-subtle display of this component of female beauty.


The pioneering research of the late evolutionary psychologist Dev Singh revealed the importance of the waist-to-hip ratio for the attractiveness of women’s bodies.  Specifically, if you measure the circumference of the waist and place it over the circumference of the hips, the closer the ratio is to about .70, the more attractive the body is judged to be.  In other words, having a waist that is slightly less than three-fourths the size of your hips will attract the greatest number of admiring glances.  This too is an honest signal that women are smack dab in the middle of the “Goldilocks” just-right zone of child-bearing age

One clever study even found that having the right waist-to-hip ratio helps men to remember biographical and personal information about a woman.

Pre-pubescent boys and girls do not differ in their waist-to-hip ratios—it is usually about .90.  However, at puberty, when females become reproductively capable, the waist-to-hip ratio begins to shift downward; for men, this is not the case.  As women age, the waist-to-hip ratio begins to creep upward again.

When I describe the waist-to-hip ratio in class, many of my students will object that the Western bias toward thinness in women is totally a cultural construct, and that in different times and places, larger female bodies were more strongly preferred.  This is true, but one thing that has not changed historically or cross-culturally is the preferred waist-to-hip ratio.  Remember that attractiveness is signaling youth and health.  In societies where disease and starvation are prevalent, a woman with some meat on her bones is in fact advertising health and access to resources, whereas a thin woman may be advertising disease or poor nutrition.  In such places, a larger body size for women will be preferred, but the proper waist-to-hip ratio must be maintained for her body to be judged as attractive.

In industrialized societies where obesity had become a health problem, thinness came to symbolize not only youth, but fitness and health as well.