What makes a man attractive? Hint: Look at his limbs

A man may be attractive because of his curly, blond hair or slick pin-striped suit, but strip everything away and one luring—maybe evolutionary—piece remains, a new study finds: how proportional his body is, especially his legs.

Women prefer a man with legs that are about half his height, according to previous research; scientists believe that is an evolutionary result of women wanting to choose only healthy men. Legs that are too short, for example, have been linked to type 2 diabetes. But other proportions, such as arm length to body height or whether the elbow and knee divide a limb in half, can also relate to a person’s health. Do they influence women’s views as well?

To answer this, researchers collected average body proportions from roughly 9000 men in the U.S. military and used them to create computer-generated images of male models (pictured). The scientists made the model’s arms and legs slightly longer or shorter, and then asked more than 800 heterosexual U.S. women to rank each model’s attractiveness.

How long the model’s arms were relative to his height didn’t seem to matter, the team reports today in Royal Society Open Science . And women cared only a little about how the elbow or knee divided a limb. But as seen in previous work, women noticed if the legs made up more or less than half his height—and they didn’t like it.

The study’s focus on the United States and its exclusion of gay men limit its findings, but it does suggest that if looks aren’t everything, proportions just might be.