Women find a man more attractive once they learn he has a wife or girlfriend, a study suggests.
They think he is more likely to be kind and faithful and, therefore, a good dad, psychologists believe.
Having a partner gives men an “attractiveness boost”, they say.
The findings come from an experiment testing the notion of “mate-choice copying”, which is seen in female birds and fish.
It can offer an evolutionary advantage by boosting their chances of finding a good sexual partner.
Researchers asked 49 female volunteers to rate men’s faces, men’s hands and a piece of art.
But when they were shown others’ ratings and asked again, they moved 13 per cent closer to the average facial score and 14 per cent closer to the average art rating.
Research leader, Dr. Kate Cross, from the University of St Andrews, said: “Women appear to copy the mate preferences of other women, but this might simply be because humans have a general tendency to be influenced by the opinions of others.”