Nearly 5000 women, most of whom were in their early 20s, were asked to participate in a quick online survey where they choose which male face they found to be most attractive. The photos were very similar - but was made to be more "masculine" with a stronger jawline and bushier eyebrows - while another was given slightly finer features. Apparently, "manly men" are less attractive to women in healthier, modern countries.
In short, women in less healthy countries preferred more masculine men, perhaps for their evolutionary advantages (testosterone is linked to health). So if you're blessed or burdened with a short, broad face and a strong jawline, you might want to think about moving to Argentina.
Jena Pincott, author of Do Gentlemen Really Prefer Blondes? wrote a piece in the Wall Street Journal about the phenomenon, too -- and outlined some of the study's limitations. It's well-worth reading.
I'm a skeptic of evolutionary psychology, generally. The women-want-a-caveman-to-protect them argument never seemed to jive with contemporary sociological research (including my own mate-preferences research) Socialization is a powerful force. And from my vantage point, the metrosexuals seem to be doing just fine.