快猫短视频

Female monkeys spend more time staring at males with strong masculine facial features. But it鈥檚 not clear why their gaze lingers like this.

Face structure often varies between male and female members of a species. In humans, men tend to have heavier brows, squarer jaws, deeper-set eyes and thinner lips than women.

Some researchers believe that facial masculinity signals mate quality, but this is hotly contested. To find out, , who was at Roehampton University in the UK when the study was performed, and his colleagues examined facial preference in monkeys.

They studied 107 free-ranging female on the island of Cayo Santiago in Puerto Rico. Each female was simultaneously聽shown two聽photos of male faces,聽one of which was聽more masculine than the other. Masculine features included bigger jaws, longer noses, and smaller eyes.

When the two聽faces聽had similar levels of masculinity, the females spent equal time observing them. But when the differences were more obvious, they spent an average of 1.9 seconds staring at the more masculine face, compared to 1.5s looking at the less masculine one.

The Ferrari theory

There are several reasons why the female macaques may have gazed longer at the hyper-masculine faces, says Rosenfield, who is now at Pennsylvania State University.

They may have been attracted to them, perhaps because they associated them with better genes. Alternatively, they may have been scared of them because they associated them with aggression.

In humans, facial masculinity is related to higher levels of testosterone. This hormone is known to dampen the immune system, so too much of it might be a bad thing. However, one theory is that only high-quality males can tolerate excess testosterone and waste energy on developing extra-masculine features.

鈥淚t鈥檚 a bit like a guy saying 鈥榣ook at me ladies, I鈥檓 such a high-quality male that I can waste money on buying a Ferrari and I鈥檓 still fine鈥�,鈥� says at Macquarie University in Australia.

A monkey鈥檚 monkey

Alternatively, females might gravitate towards macho males because they are better at competing for resources and protecting the group from outside attacks, says at the University of Queensland. 鈥淔acial masculinity is correlated with other testosterone-dependent traits like muscularity, height and competitive ability,鈥� he says.

This fits with human studies, which have shown that women tend to be more attracted to macho men in societies where income inequality, crime and violence are rife, says Dixson. 鈥淭hen it鈥檚 probably beneficial having a more intimidating, aggressive partner who can compete for scarce resources,鈥� he says.

Rosenfield and his colleagues are now planning to test these ideas. For example, they want to determine whether male macaques with more masculine faces really do have higher levels of testosterone or aggressive tendencies, and whether they have healthier offspring.