Why do the majority of women prefer more masculine faces in men? Previous research has suggested this is due to changes in women’s fertility hormones and the idea that masculine men appear to have a greater genetic “fitness” for reproduction.

A team of researchers from the University of Glasgow, however, has recently found that women’s perception of male attractiveness is not linked to fertility-related hormonal changes.

The researchers collected data from nearly 600 heterosexual women over the course of five years and found that while the majority of women prefer more masculine faces, it has nothing to do with changes in hormone levels.

This research is the largest to date on the subject.

“This study is noteworthy for its scale and scope — previous studies typically examined small samples of women using limited measures,” Benedict Jones, professor of psychology at the University of Glasgow, said in a statement. “With much larger sample sizes and direct measures of hormonal status, we weren’t able to replicate effects of hormones on women’s preferences for masculine faces.”

The paper is published in Psychological Science.

The Study

The researchers recruited 584 women to participate in weekly test sessions lasting between two and 15 weeks.

Most women participated in 10 weekly sessions, and all of the women were asked the same questions each week. These questions included if they were in a romantic relationship, and whether or not they were using hormonal contraceptives. Additionally, the women provided a saliva sample for hormone analysis.

The women then completed a face-preference task, in which the researchers showed them 10 pairs of male faces. Each pair was a digitally altered version of the same face, with one altered to look more masculine and the other more feminine.

Image: ©Jones et al

The women were then asked to select the face they found more attractive and rate the strength of their preference.

To disguise the purpose of the study, each face-preference task was interspersed among 30 filler trials assessing participants’ preferences for other facial traits.

The Findings

The researchers found, as expected, that most women preferred the more masculinized male faces to the more feminized male faces. They also found this preference to be slightly stronger when women were told to base attractiveness in the context of a short-term relationship.

However, after measuring hormone levels each week, the researchers did not find any evidence that women’s preference for masculinity changed according to fertility related-hormonal levels, such as estradiol and progesterone.

Since these results directly contradict previous studies on the subject, Jones attributes his team’s findings to the size of the sample. Before this larger-scale study was conducted, many studies came to conclusions with limited resources and test subjects.

“One study by a Finnish group found that men with more masculine faces show stronger immune responses to a vaccine, but it was a pretty small study and we haven’t been able to replicate other findings that were reported for the same group of men (e.g., that men’s facial attractiveness is predicted by a combination of their cortisol and testosterone levels) in our lab,” said Jones. “So, I’m a little skeptical of the claim that masculinity is attractive because it signals a strong immune system.”

Because of this, Jones found the results to be both surprising and expected.

On the one hand, this new research contrasts previous findings that fertility hormones affect women’s mate preferences, but on the other hand, having a larger-scale study allows for a fuller understanding of the topic.

“One of the things I think is really important about the work is that it highlights the importance of going back to reassess widely accepted results from the literature with better methods to see if the effects hold up,” said Jones. “On this occasion they didn’t, which really underlines the importance of keeping an open mind about what results are and are not robust.”

“The work was published in one of the top ranked Psychology journals. That’s important because it shows that even the very best journals are increasingly open to publishing research that challenges assumptions about what we think we know. That’s a very good thing for science, in my opinion.”