Women can judge a man’s attitudes towards casual sex by looking at their face structure, but the same is not true for men gazing at women, according to a new study. The research has got some big limitations to consider, but the study authors argue their work shows an interesting example of how facial structure and appearances may act as a “valid cue” to sociosexuality,

As reported in the journal Evolution and Human Behavior, two researchers from Macquarie University in Australia gathered 123 young people and asked their to fill out a questionnaire on their attitudes towards sexual relationships, after which they were photographed.

Next, they asked 65 volunteers to look at the photograph of the questionnaire respondents and asked them to guess their willingness to engage in a casual sexual relationship. As per their findings, women were able to guess with high accuracy the men that were more open to casual sex. However, men were not able to accurately guess the women’s sociosexual orientations.

“This surprised us,” Ian D. Stephen, study author and an associate professor of psychology at Macquarie University, said in a statement. “The ability to make these judgements would also be really useful to men who are trying to judge who might be interested in short-term uncommitted relationships, and who might be more interested in something longer-term and more serious.”

To affirm this discovery, participants were also presented with composites of faces of people with more unrestricted sociosexuality, as well as composites of faces of individuals with more restricted sociosexuality. The participants were asked to guess their attitude toward casual sex and, once again, they were able to guess the more unrestricted sociosexuality male, but not female.

The researchers also found men who were open to casual sex were closely associated with particular facial features, namely longer faces, higher foreheads, longer noses, and larger eyes. The reason behind this link is not certain, but the researchers speculate it might have something to do with testosterone levels.

“We think this points to a role for testosterone,” explained Joe Antar, study co-author from Macquarie University.

“Higher levels of testosterone are associated with more masculine-looking facial features, and with more male-typical behaviour like interest in short-term, uncommitted relationships. Because testosterone plays a much smaller role in female development, this would also explain why the information about relationship intention does not appear to be present in women’s faces," Antar continued. 

"But we need to do more research to know for sure,” he added.

As mentioned, there are a few more caveats to consider. First of all, the sample size was on the small side (around 100 people) and all participants were white and presumably heterosexual, which is not representative of the wider population.

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