We are told not to judge a book by its cover, but new research indicates that sometimes, those inclinations are correct. Women can often tell if a man is likely to be a cheater from their face alone.
Men weren't able to see the same in women.
This is "the first evidence that faithfulness judgements, based solely on facial appearance, have a kernel of truth," the researchers write in the paper, published today, Dec. 4, in the journal Biology Letters. "It seems remarkable that such impressions have any accuracy at all, given how poor accuracy is even with extensive behavioral information."
The researchers asked university students (34 men and 34 women) to rate photographs of 101 male and 88 female faces from photos. They were asked to rate how masculine or feminine the faces were, and how likely they were to be a cheater.
The images were from a set created in 2005 by the researchers, led by Gillian Rhodes of the University of Western Australia, which included about half self-admitted cheaters.
From the pictures alone, women were relatively accurate (they were wrong 38 percent of the time) at determining if a man had been unfaithful in the past. This unfaithfulness was linked to how masculine a man's face was, but not to his attractiveness.
Men weren't able to accurately tell if the female photos were faces of cheaters, guessing wrong 77 percent of the time.
That wasn't the only thing they were wrong about. To the men a woman's "attractiveness and femininity were highly correlated with unfaithfulness ratings, and each other, indicating that men perceived attractive, feminine women as likely to be unfaithful. However, there was no evidence that they were," the researchers write.
Another recent study indicated that the masculinity of a man's face wasn't linked to testosterone levels, or two how strong their immune system is (two indicators of a good evolutionary mate). Since cheating is evolutionarily bad (the male's investment in potential offspring would be decreased, or absent) these subconscious readings of a man's face may be working on concert to help women pick good mates.