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What makes a man's body attractive? In many mammalian species, females evolved to prefer the strongest males. According to research from Griffith University, the same is true of humans.

Dr Aaron Sell from the School of Criminology and Criminal Justice said cues of upper body strength make a man attractive, including having wider shoulders, being physically fit and having greater handgrip strength.

"Evolutionary psychologists have shown that women's mate choices use many cues of men's genetic quality and ability to invest resources in the woman and her offspring,'' he said.

"Among our ancestors, one variable that predicted both a man's genetic quality and his ability to invest was the man's formidability. Therefore, modern women should still have mate choice mechanisms that respond to cues of a man's fighting ability.

"One crucial component of a man's ability to fight was his upper body strength."

In the study, the researchers tested how important physical strength is to men's bodily attractiveness by showing women pictures of men's bodies and asking they how attractive they were.

The results showed that it was possible to almost perfectly predict how attractive a man's body is from three things: how physically strong he looks, how tall he is, and how lean he is. The effect of strength was so large that none of the 150 women in the study preferred weak men. Furthermore, looking strong was much more important for man's attractiveness than being tall or lean.

"The rated strength of a male body accounts for a full 70 percent of the variance in attractiveness,'' Dr Sell said.

"The effect of height and weight on attractiveness may indicate that women are responding to cues of health or to the benefits that height and lean bodies have in protracted aggression, hunting and other aspects of fighting ability."

Dr Sell said while the women in their study preferred the strongest bodies, there was a sizeable dataset across many cultures that showed women did not always prefer the strongest looking faces.

The study was published in Proceedings of the Royal Society B today.

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More information: Aaron Sell et al. Cues of upper body strength account for most of the variance in men's bodily attractiveness, Proceedings of the Royal Society B: Biological Sciences (2017). Journal information: Proceedings of the Royal Society B Aaron Sell et al. Cues of upper body strength account for most of the variance in men's bodily attractiveness,(2017). DOI: 10.1098/rspb.2017.1819