To those who would like to argue that sex differences are exaggerated or of minor importance in human behavior, I have two words:
Estrogen
Testosterone
These two hormones control much of human behavior and separate the sexes dramatically. In fact, people can change genders, at least partially, by taking large amounts of the hormone prevalent in the opposite sex. Of course, women have some testosterone, and men have a small amount of estrogen. While there are standards for normal levels in both sexes, there are an infinite number of variations, and hormone levels can change over time. However, the hormones play a huge role in physical development during puberty, marking males and females in ways that are not malleable.

All women know that female attraction triggers span a wide spectrum. For every woman that loves a ripped, hairy chest, there’s one who likes a pale, slim, hairless torso. Some of us are drawn to laid back guys who don’t fret about their feelings much, others are drawn to brooding loners or sensitive ponytail men. We’re less reliant on visual criteria than men are, but many women do have preferences when it comes to guys’ looks.

There are three fascinating studies that have looked at what women prefer in male facial features. The esteemed Face Research Lab in Aberdeen, Scotland uses technology to generate face pairs with more and less masculine facial features for these studies.

I. Facial correlates of sociosexuality
A couple of years ago I wrote the post Player or Boyfriend? It’s Written On His Forehead, about a 2008 study where 700 subjects correctly judged (72% of the time) whether faces in photographs belonged to people who preferred casual sex or relationships, based on their sociosexuality score. The differences in the faces were explained by hormones, and as you might expect, higher testosterone males were more interested in casual sex than other males. What surprised researchers was that women showed a marked, significant preference for the lower testosterone, relationship-oriented men, for both short-term and long-term mating. (Note: only heterosexual male faces were included.) This happened at the intuitive level, and the researchers believe it may be a mechanism whereby women may avoid men seeking short-term sex.

II. Partner characteristics associated with masculinity, health and maturity in male faces
Lynda Boothroyd, who led the study above, also conducted an earlier study looking at the degree to which women select men for masculine facial features. The summarized results: The more attractive, or “healthy” a face, , the more it was perceived as displaying desirable characteristics. More masculine and older faces were perceived as having more ‘alpha’ traits and less likely to be a faithful and committed partner.
As predicted, across both studies male facial masculinity was associated with higher levels of perceived dominance, but lower perceptions of commitment and fidelity within a long term relationship. This supports previous research into masculine vs. feminine faces. It is concordant with Perusse (1993) behavioral data showing that high status men are less likely to settle into a long term relationship and tend to have more sexual partners, and Mazur and Michalek (199 data showing a link between testosterone in males and marital problems.

III. The health of a nation predicts their mate preferences
Science journalist Jena Pincott penned Why Women Don’t Want Macho Men for the Wall St. Journal. The study included 4,800 females in their early to mid 20s, from 30 countries. (Note: the researchers used only white subjects to control the study.)
Women with the weakest masculinity preferences came from the countries with the best health care, including Belgium, Sweden, Finland, Denmark and Austria. Those with the strongest preferences for macho men came from the unhealthiest countries, including Mexico, Brazil, Bulgaria and Argentina.

The U.S. came in fifth in the masculinity ranking, and 20th in the health care ranking. It would be interesting to see the American results broken out by socioeconomic status, as we know there are profound differences among sub-populations in the U.S. with respect to marriage and divorce.
Pincott posits that female preferences in the U.S. have other reasons to shift. The promise of potentially improved health care may alter attraction triggers. Also, women’s increasing financial freedom means they are freer to prefer men who are caring, cooperative and communicative. Finally, as women control more resources, they prefer better looking men. Based on this study, that’s more likely to be a pretty boy than a macho dude.
It seems reasonable to wonder if before long American women will have redefined “the perfect male” – not the cad, but the dad. In the meantime, choosing the right long-term partner is a matter of extreme importance. Now you know what he looks like, more or less.