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Key points
- High testosterone levels in men predict more masculine facial features and unrestricted sociosexuality (higher acceptance of casual sex).
- To a lesser extent, more feminine, attractive faces predict unrestricted sociosexuality in women.
- People are able to interpret masculine versus feminine facial structure to infer sociosexuality.
Imagine you’re out and have met someone both attractive and new. Wouldn’t it be great if you could tell, just by studying their face, whether they’re interested in a long-term relationship versus just one night of fun?
A new study published in the July edition of Evolution and Human Behavior confirms that this is somewhat possible, especially when judging men. To test their hypothesis, researchers asked 103 participants to describe their own “sociosexuality,” which is a measure of how accepting one is of short-term, casual sex. Next, they recruited another 65 participants who were asked to make guesses about the sociosexuality of each person in the first group just by looking at a photograph of their face.
The study had two important findings. First, among men, self-reported sociosexuality correlated with having more masculine-looking facial features. Second, female participants were remarkably good at guessing each male subject’s sociosexuality just by looking at their photograph. Although previous research suggests that males can also make accurate guesses about females' sociosexuality, this effect only happens when they are able to observe video footage.
Understanding "Sociosexuality"
For decades, researchers have studied individual variation in sociosexuality. A person who has “unrestricted sociosexuality” has more positive attitudes toward casual sex and is more likely to engage in hookups than a person who has “restricted sociosexuality.” A person who has restricted sexuality is typically only interested in seeking longer-term relationships.
In a highly cited article, researchers developed a validated scale to measure individual differences in sociosexuality. The scale is relatively straightforward. Questions ask, for example, how often you engage in casual sex, how often you fantasize about having sex with a person you’ve just met or don’t know well, and the extent to which you believe that sex needn’t always require love.
What Shapes Sociosexuality?
A person’s sociosexuality is impacted largely by societal factors. Individuals who grow up in more socially conservative families and communities tend to have more restricted sociosexuality, meaning they are typically less accepting of casual sex hookups and are more oriented toward longer-term relationships than those who are raised in less conservative environments. A person’s sociosexuality can evolve, however. This frequently happens with young adults when they either go off to college or start living independently from their parents.
Beyond culture, research also consistently shows that sociosexuality is rooted in biology. Males who have higher (versus lower) levels of testosterone tend to have less restricted sociosexuality. To a much lesser extent, females who have higher (versus lower) levels of estrogen also have unrestricted sociosexuality.
Testosterone and estrogen yield powerful and visible effects on the body. In addition to driving the development of secondary sex characteristics during puberty, both hormones determine certain facial characteristics. Males with higher levels of testosterone tend to have wider faces, more space between their eyes, wider noses, thinner lips, and a stronger, larger jawline than males with less testosterone. Estrogen tends to make faces smoother and softer with more rounded cheeks.
Although previous research shows that men can predict above chance a women's sociosexuality, the current study suggests this is related to observing physical features beyond just facial structure.
Sociosexuality, Masculinity, and Attractiveness
In research where women are shown pictures of male faces, women tend to rate the faces of men who have higher testosterone levels as being more masculine but not necessarily more attractive.
When men are shown pictures of women, they tend to rate those with the most feminine and symmetrical-looking faces as the most attractive. Whereas for men, it is masculine-looking facial features that relate to sociosexuality, for women, it is a much more subjective judgment based on overall perceived beauty that is less likely to be rooted in biology.
Given that testosterone influences facial features and sociosexuality in men, it makes sense that a male’s facial features would provide visible clues about his sociosexuality to an observer.
An interesting question is, why did men and women evolve this way? What adaptive purpose might it serve?
An Evolutionary Explanation?
Evolutionary psychologists believe that perhaps since pregnancy and child-bearing present greater risk and more burden for women versus men, it behooves women to know which men are more likely to stick around during and after pregnancy to provide food and resources. Obviously, this interpretation doesn’t reflect modern ideas surrounding gender, but it may have been accurate millions of years ago during critical periods of evolution. Simply put, at some point in human evolution, it probably paid off for women to know which men were in it for the long haul. And that ability apparently still exists today.
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