Wrinkles, furrows, lines and gray hair are not the only cues that tell others we're aging. You may not realize it, but facial skin color distribution--or skin tone--can add 10 to 12 years to a woman's perceived age, according to researchers from the University of Göttingen in Germany. The No. 1 cause of uneven skin tone? Tanning.

Using 3D imaging and morphing software, the researchers removed potential age-defining features, such as wrinkles, lines and facial furrows, from the photographs of various women. That meant the only variable left was skin tone. These photos were then viewed by 430 observers who were asked to estimate each model's age and gauge her health and attractiveness.

The results? Faces with more even skin tone and luminosity were judged to be younger, as well as more attractive and healthy. The models with uneven, blotchy skin tone were judged to be significantly older.

"Whether a woman is 17 or 70, the contrast of skin tone plays a significant role in the way her age, beauty and health are perceived," says study co-author Dr. Bernhard Fink. "An even skin tone can give visual clues about a person's health and reproductive capability, so it is considered most desirable."

Skin tone variances can be caused by three primary  factors:

1. UV damage from the sun: freckles, moles and age spots
2. Natural aging: yellowness and dullness
3. Skin vascularization: redness

The study findings were published in the journal Evolution and Human Behavior.

--From the Editors at Netscape