Using a complex set of algorithms calculated by a computer, researchers found the length of the grooves that run from the side of the nose to the corners of the mouth (nasolabial grooves) best predicted a person's perceived age. Interestingly, in this study of 120 females in their 40s, the wrinkles (crow's feet) around the eyes were the least predictive!
PositiveTip: Avoid smoking and tanning beds to give yourself the greatest chances of a youthful appearance as the years pass.