A fascinating study.

FORT WORTH, Texas — The beautiful people get all the breaks. A new study finds an interesting link between how attractive someone is and the strength of their immune system.

A team at Texas Christian University found that when people had to rate a group of photos based on the attractiveness of each person’s face, they consistently rated individuals with stronger immune health as more attractive than other photos in the study.

Although beauty is often in the eye of the beholder, researchers say there has been a historical link between what societies consider attractive and reproductive success. The TCU team theorized that, because certain evolutionary traits tie into more mating success, people who seem more attractive to others may also appear healthier to the opposite sex.

To test that theory, researchers gathered 159 men and women and photographed each one without makeup and while displaying a neutral expression on their face. Study authors then took blood samples from each person to measure their levels of white blood cells — which battle disease and infections.

The team then brought in 492 other people to rate members of the opposite sex in these photos based on their attractiveness. The volunteers did not have any information on each person’s immune health and only had that one neutral photo to base their rating on. Results show people with stronger immune systems were rated as being more attractive by the 492 volunteers.

“The current research suggests that a relationship between facial attractiveness and immune function is likely to exist,” corresponding author Summer Mengelkoch and her team write in the journal Proceedings of the Royal Society B.

Opposites attract

Interestingly, the study finds men and women have very different ideas about what makes a face attractive and healthy. Researchers found that, on average, women rated men with higher levels of NK (natural killer) cells as more attractive. These cells play a key role in fighting off and killing bacteria.

Men, on the other hand, found women with lower NK cell levels in their blood more attractive. Study authors believe the reason for this is women with lower NK levels generally have higher estrogen levels — a hormone important to sexual reproduction.

As for which features are likely to stand out and attract attention, researchers found a not-so-surprising list of qualities people look for in a pretty face.

“Features such as clear skin, prominent cheekbones, bright eyes, and full, red lips have been deemed attractive throughout recorded human history,” the researchers write.