We’ve written before about the types of faces women find attractive (see here and here). In addition to those studies, one of the more well-known findings in the facial attractiveness literature is that women show a preference for more masculine faces when they are ovulating, but actually tend to prefer less masculine, or more feminized, faces when they are not likely to conceive a child. Why the shift in preference? The theory is that more masculine features = better genetic quality, but masculinity comes with a whole lot of baggage, such as being less concerned about others’ welfare, being less honest, and so on. Clearly, this baggage doesn’t bode well for a long-term relationship. So to maximize outcomes, women show the preference for masculinity when it matters (i.e., during ovulation), but then shift focus to more nurturing types the rest of the month because masculine guys just aren’t as trustworthy.

In an absolutely ingenious study coming out in Psychoneuroendocrinology, Theodoridou and colleagues put the theory to the test by manipulating women’s and men’s feelings of trust and then looked at the extent to which they preferred masculine and feminine faces (in both women and men). How’d they do that? They used nasal inhalers to administer oxytocin, a neuropeptide (i.e., chemical) that, among other things, can increase feelings of trust. They used a nasal inhaler because it’s the easiest way to ensure that the oxytocin passes the blood-brain barrier (far easier than sticking a needle in people’s brains). The idea was that masculinity would be preferred in male faces, in general, if you chemically alter people’s general feelings of trust, making them less likely to view masculinity to be associated with bad social characteristics. They didn’t expect a change in preference for female faces given that femininity is already preferred anyway. Subjects were then presented with a series of digitally-altered male and female faces whose balance of masculine (e.g., squarer jaw) vs. feminine (e.g., rounder face) characteristics could be changed by a swipe of a computer mouse. They were instructed to ‘shift’ the faces to be more masculine vs. feminine by sliding the mouse to the left versus the right until they got the face to be ‘as attractive as possible.”

What happened? Both male and female subjects receiving the oxytocin (vs. a placebo) showed a preference for masculinity in male faces, but not females’ faces. That’s right, even the guys tended to like more masculine guys when their trust levels were boosted (probably because they could stop worrying that the computer-dude won’t beat them up or steal their mate). For women, the oxytocin helped them overlook the negative characteristics typically associated with masculinity, all the while preserving the guys’ genetic superiority. Gotta love science!

Interested in learning more about relationships? Click here for other topics on Science of Relationships. Like us on Facebook to get our articles delivered directly to your NewsFeed.