It looks like the eyes do have it, after all.
Research published in the journal Biology Letters has found that women are able to tell just by looking at an unfamiliar male face whether he is "sexually untrustworthy", or a cheater.
Men are not nearly as accurate when asked to determine the same for women.
The study was based on an experiment conducted with 34 men and 34 women. The researchers showed them 189 color photographs of Caucasian faces and asked the participants to rate the faces by level of "trustworthiness".
The people who had posed for the 189 photographs also gave to researchers self-reported accounts of their sexual history.
The study authors, from the University of Western Australia, wrote, "Women's ratings of men's unfaithfulness showed small-moderate correlations with men's past unfaithfulness (cheating, poaching)."
Women judged more masculine men to have been more likely to cheat. They did not factor attractiveness in their decisions.
Men, on the other hand, assumed that more attractive women were more likely to have cheated. That was not the case.
"We conclude that impressions of sexual faithfulness from faces have a kernel of truth, at least for women, and that they may help people assess the quality of potential mates about whom they have minimal [behavioral] information," the researchers write.
Evolutionary psychologists and this team of researchers suggest that, in the beginning of human history, it was simply more important for women to judge whether men were cheaters rather than the other way around.
Men whose mate cheated risked raising another man's wife. However, women whose partners were unfaithful risked losing resources to competition.
Nowadays, it is probably more important for men not to stray, however.
A recent study found that unfaithful men were more likely to have heart attacks. However, the study does have its limitations. It was conducted with a rather small sample size.
In addition, it is unclear whether the results would still hold true if the photographs contained people of different races.