Standards of beauty vary somewhat from culture to culture. Personal tastes differ as well. However, over the last few decades, evolutionary psychologists have identified several elements of attractiveness that are universal.

The physical features we find attractive are cues to a person’s reproductive abilities. After all, sex is about getting our genes into the next generation, so it makes sense that we want to mate with people who can help us achieve that goal.

   David Ludden Ph.D.
    David Ludden Ph.D. is a professor of psychology at Georgia Gwinnett College. He received his Ph.D. in cognitive psychology from the University of Iowa, and is the author of The Psychology of Language: An Integrated Approach. He will be focusing on the role that language plays in human psychology–from perception to persuasion, from attention to attitudes, from motor skills to mental states.

Editor:  Arman Ahmed

Across cultures, men and women agree on certain physical traits they find desirable in a mate. For example, men prefer women who are younger and have hips wider than their waist, because both of these signal the ability to bear children. Likewise, women prefer men who are older and have shoulders broader than their waist, because these both indicate a capacity to provide resources for child rearing.

Another universal among mate preferences is good health—and for obvious reasons. But how does one assess the health of a potential mate? As Canadian psychologists Daniel Re and Nicholas Rule point out in a recent Current Directions in Psychological Science article, your health is written all over your face.

The researchers point to three facial features that are reliable indicators of health. Even untrained observers can readily spot these, which suggests that people have an innate mechanism for assessing the health of others. Two of these features involve facial color and the third is related to adiposity, or fat. (Rule No. 1 in psychology: Never use a short, simple word when a long, complex word will do just as well.)

The first facial feature signaling health is redness of the skin. Oxygenated blood is bright red, and this coloration shows up in the face as blood flows through the capillaries of the skin. Deoxygenated blood has a bluish tinge and leaves the skin looking pale. Many disorders, ranging from iron deficiency to respiratory disease, have a negative impact on blood oxygen levels and even short-term illnesses such as colds or the flu can leave the blood anemic. Lifestyle choices also have an impact on skin redness. The researchers note that an increase of just one hour a week of aerobic leads to a noticeable difference in skin redness.

The color red seems to hold special significance for humans, as well as for primates. The ability to distinguish red from green is unusual among mammals, but it’s a typical feature of primate visual systems. (Lack of red-green discrimination is the most common form of color blindness in humans.)

Evolutionary psychologists have speculated on the advantages of seeing red. Some propose that it helps primates distinguish ripe from unripe fruit. Others suggest that primate males use it to recognize sexual receptivity in females, whose genitalia become engorged with blood. But, because primates have relatively hairless faces, seeing red could also help them assess the health of other members of their group. After all, you may want to stay away from someone who’s sickly. And if you’re an ambitious beta male, a pallid look on an alpha male’s face may signal an opportunity to usurp leadership.

The second facial feature of health is yellow coloration. Many fruits and vegetables contain carotenoids, which impart a yellowish orange color to the skin. Carotenoids are antioxidants that support the functioning of the immune system. Diseases of the immune system tend to deplete carotenoids in the body, thus leaving the skin pale.

In research studies, people rate faces with a yellowish glow as more attractive than pale faces. Further, scientists found that just three servings a day of fruits and vegetables lead to noticeable increases in the yellowness of the skin within six weeks. Eating your veggies isn’t just good for you; it actually makes you more attractive.

The researchers also point out that people can detect changes in red or yellow despite levels of melanin in the skin. Melanin is the dark pigment responsible for the various shades of brown skin coloration that we use as a marker of race or ethnicity. It’s also the pigment in fair-skinned people who become tan from sun exposure. (By the way, tanning-bed junkies, studies show that people rate faces as more attractive when they have a reddish glow than when they’re tanned.)

Although red and yellow in the skin are signs of good health, the researchers point out that excessive redness or yellowness is a sign of poor health. Thus, faces aglow with oxygenated blood are rated attractive, whereas those with sunburn are not. Likewise, excessive yellow in the skin is a sign of liver disease.

The last facial cue to health is adiposity, or fat deposits. Body mass index (BMI) is the standard method of determining whether a person is of normal weight and is calculated as a ratio of height to weight. However, as the researchers indicate, the BMI isn’t always an accurate assessment of body fat.

In particular, people with significant amounts of muscle mass are rated as overweight, even though their levels of body fat are quite low. Since fat deposits in the face typically reflect fat deposits around the rest of the body, the researchers argue that a visual inspection of the face is a better indicator of body fat than BMI.

The researchers advocate for including these three face tests—redness, yellowness, and fatness—as part of a physician’s general assessment during medical exams. But they acknowledge that some doctors may already do this, on an unconscious level. After all, even untrained research participants can distinguish faces that look healthy or unhealthy on the basis of these three criteria: It’s part of our intuition to quickly assess the medical condition of each person we meet.

The take-home message is simple: If you want to boost your attractiveness, forget about cosmetics and tanning beds, Botox and liposuction. Instead, lead a healthy lifestyle with a balanced diet and get plenty of exercise. You’ll not only look more attractive to other people, you’ll also feel better about yourself.