Can the shape of your face affect the length of your relationship?

According to a new study led by Anthony Little from the University of Stirling and Benedict Jones from the University of Glasgow, evolutionarily speaking, mate selection may be linked to facial shape and structure.

Researchers studied several hundred heterosexual male volunteers using a composite picture of women's faces, asking the men which women they were most likely to choose for a long or short-term relationship.

Each face had two versions, one with slightly more "feminine" features like a smaller jawline or fuller cheeks, and the other with more "masculine" features. The faces were originally taken from either European or Japanese women.

They found that the men were more likely to rate the feminine faces higher for a brief fling, the preference especially strong for men already in a committed relationship. 

"When a man has secured a mate, the potential cost of being discovered may increase his choosiness regarding short-term partners relative to unpartnered men, who can better increase their short-term mating success by relaxing their standards," the study authors wrote in the British Journal of Psychology.

But when it came to choosing a long-term mate, men were more likely to pick more masculine faces. The researchers noted that men "may actually prefer less attractive/feminine women" when making long-term choices.

Feminine features are associated with higher levels of estrogen, which is linked to reproductive success. Similarly, studies have found that women tend to prefer more muscular and "hunky" men for a fling, but are more likely to settle down with someone more average-looking, possibly a more reliable bet for raising children.