Well: The Well Smoking Quiz: Who Looks Older?

We know that smoking is bad for you — and that it ages you prematurely. Now a study provides photographic evidence for this claim.

Scientists gathered health and lifestyle information on 79 pairs of identical adult twins who fit into one of three groups: a pair in which one was a smoker and the other had never smoked; a pair in which both were smokers; or a pair in which both were smokers but with at least a 5-year difference in the duration of their smoking habit. They photographed them and had independent judges rate the pictures side-by-side for wrinkles, crow's feet, jowls, bags under the eyes, creases around the nose, lines around the lips and other evidence of aging skin.

The differences in some other factors that can age skin prematurely — alcohol consumption, sunscreen use and perceived stress at work — were statistically insignificant between twin pairs. But the judges' decisions on which twin looked older coincided almost perfectly with their smoking histories.

"The purpose of this study was to offer scientific evidence that smoking changes not only longevity, but also quality of appearance," said the senior author, Dr. Bahman Guyuron, chairman of the plastic surgery department at University Hospital, Case Medical Center in Cleveland. "It is harmful any way you look at it."

In the five twin pairs shown, click on the photo of the twin you think is the smoker or who smoked longer.