Want others to think you're hot? Flashing them a gross picture of bodily fluids might work, a new study suggests. An important caveat, though -- the findings only held for those with symmetrical faces.
Recent research showed that as the health of a nation worsened, women were more partial to more masculine faces. Perhaps, the scientists conjectured, in environments where health was a bigger concern, women might choose more masculine men, unconsciously making a mental trade-off between the potential costs (manly men have been shown to be dishonest and more interested in short-term flings) and benefits of greater masculinity (such as better health).
But could just a hint of sickness swerve mate preferences as well?
To find out, researchers created a study in which 117 male and 124 female heterosexual volunteers rated the attractiveness of dozens of faces. These included symmetric and asymmetric versions of the same face as well as masculinized and feminized versions of the same face. People tend to link symmetric faces with health, perhaps because asymmetry is a sign of stress during development. Past research has shown that people with more symmetric faces have fewer colds than more asymmetric individuals.
The scientists then had the volunteers look at pictures that hinted at varying levels of sickness. For instance, a white cloth with a yellow-red stain resembling that made by a bodily fluid was a strong clue of disease, while a blue stain was not. The volunteers then were asked to judge the attractiveness of faces again.
They found that disgusting images increased the preference for symmetric faces in both men and women. Repellant pictures also made men prefer more feminine faces, or those that are rounder and have fuller lips, and women prefer masculinized faces, or those with larger jaws and heavier brows.
"The work highlights just how flexible preferences are — only a short exposure to a few different pictures is required to change what people find attractive," researcher Anthony Little, a psychologist the University of Stirling in Scotland, told LiveScience.
"Lots of people think evolutionary work is focused on genetic and unchanging aspects of human behavior, but here there is something quite different," Little added. "People seem to adapt their partner preferences to their environment based on what they see around them. If you see lots of potential for disease in your current environment, then valuing healthy partners is a very sensible response."
It remains an open question as to how long this effect might last.
"The effect might be fleeting — given our results, though, we would predict that those who are constantly exposed to cues [of] germs and disease would have different preferences from those who are not exposed to such cues," Little said. "So while our experimental effects may be short-lived, they can reflect long-term effects if people were continually exposed to such cues."
The scientists detailed their findings online Nov. 30 in the Proceedings of the Royal Society B.
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