According to an Australian study, in a paper that appeared in the journal Biology Letters, researchers found that women can tell with some accuracy whether an unfamiliar male is faithful simply by looking at his face, but men seem to lack the same ability when checking out women.
The researchers found that women tended to make that judgment based on how masculine-looking the man was.
"Women's ratings of unfaithfulness showed small-moderate, significant correlations with measures of actual infidelity," wrote the team, led by Gillian Rhodes at the ARC Centre of Excellence in Cognition and its Disorders at the University of Western Australia in Perth.
"More masculine-looking men were rated as more probable to be unfaithful and having a sexual history of being more unfaithful."
Attractiveness was not a factor in the women making the link.
In the study, 34 men and 34 women were shown colour photographs of 189 Caucasian adult faces and asked to rate them for faithfulness.
"We provide the first evidence that faithfulness judgments, based solely on facial appearance, have a kernel of truth," they wrote in the paper.
Men, on the other hand, seemed to have no clue. They tended to perceive attractive, feminine women to be unfaithful, when there was no evidence that they were, the scientists noted.