A rosy complexion really does spell good health to most observers, according to a clever experiment conducted by researchers at the University of St. Andrews. The results offer one more good reason to get fit.

Intrigued by the fact that several monkey species use skin redness to trumpet their good health and sexual attractiveness, the researchers decided to test whether the same holds true for humans. They began by measuring how skin color varies depending on the amount of blood and oxygen carried in the blood. Skin is laced with tiny blood vessels which carry more oxygen-rich blood in people who are physically fit and healthy.

Using a computer graphics program, the scientists then asked volunteers to adjust the color of faces in a series of photographs to make them look as healthy as possible.

For all the faces, volunteers added more oxygen-rich blood color to make the faces look healthier. “Our evaluators all thought that bright red blood with lots of oxygen looked healthier than darker, slightly bluer blood with lower oxygen levels,” said Dave Perrett,  director of the University of St Andrews Perception Lab, which participated in the research. “It is remarkable that people can see this subtle difference.”

The findings are published in the free-access online journal PLoS One, where you’ll find a comparison of facial colorings perceived as unhealthy versus healthy.

The take-home message: Toned muscles and a slim waistline aren’t the only benefits of getting fit. By subtly changing your skin coloration, oxygen-rich blood may actually make you more attractive in subtle but powerful ways.

© 2009 PDQhealth

Tags: facial coloring, health, rosy complexion