A lonely man desperate to find a girlfriend might be well advised to hire a few women to smile at him — and let female copycat genes run their course. British psychologists have discovered that, when sizing up a man, a woman takes her cues from other women around him.

If those women are looking happily at him, that has a big influence on the woman’s assessment. The more female smiles there are, the likelier she is to consider the guy a catch.

Researchers led by Benedict Jones of the University of Aberdeen, Scotland, recruited 28 young women whose average age was 24.

The volunteers first looked at photographs of four young men wearing neutral expressions and looking directly at the camera. The men were shown in pairs, and the women had to judge which of the two was the more attractive, apportioning their preference a score on an eight-point scale.

The same faces were shown again to the volunteers. This time, though, the male faces were flanked by a female face - a woman, shown in profile, who either looked neutrally at the man or smiled at him. After this, the volunteers took another look at the paired faces, as in the first step of the experiment, and were asked to give another attractiveness rating.

Many of them revised sharply downward their initial grading of the man, by more than 10 percent on average, if his picture had been next to a woman with a neutral expression.

But they sharply revised upwards their grading, finding the man more attractive by an average of at least 15 percent, if the woman looking at him had a smile on her face.

But the reverse held true for men, the researchers found.

Twenty-eight young men volunteers took part in the same experiment - and their rating of the likeability of the male faces plummeted if the man was being smiled at by a woman. But if the woman had a neutral look, the rating went up.

The findings tell us a lot about how sexual competition affects our views, the study says. “Desired” men are more attractive to women but conversely more of a threat to other males. Among females in other species, “mate choice copying” has already been spotted among guppies, Japanese quail and zebra finches, but this is the first time the phenomenon has been confirmed empirically among humans.

Evolutionary psychologists say the copycat reflex is the result of Darwinian pressures.

If a female faces lots of potential mates but has difficulties in choosing the best one — or to do so would cost too much time or energy — she can help herself by taking a steer from how rival females behave. The paper appears on Wednesday in Proceedings of the Royal Society B, a journal of the Royal Society, which is Britain’s de-facto academy of sciences.