The history and aesthetics of the lines on your face.

Wrinkles are like new vocabulary words: Once you become aware of them, you notice them everywhere. Worry lines, laugh lines, frown lines, crow's-feet. Los Angeles, where I live, is a great city for wrinkle watching. True, in the enclaves of plastic-surgery enthusiasts—Brentwood, Beverly Hills, the sets of Hollywood films—there is nary a wrinkle in sight. But the city is also home to some of the crinkliest people you will ever see, their faces baked by the hot desert sun into relief maps of creases and furrows and crosshatching.

In the past few years, we have become quite sophisticated in our understanding of wrinkles and the various methods for erasing them. We are versed in the physical and social repercussions of unfettered aging—skin cancer, job discrimination, invisibility in a society that shamelessly values youth. Indeed, in 2007, 11.7 million Americans underwent some sort of cosmetic procedure (surgery, Botox, fillers, and the like), an 8 percent increase from the year before and a 457 percent increase from a decade earlier. Yet we also fear the sometimes-poor results of these endeavors: the blank foreheads of Botox, the wind-tunnel face-lifts favored by various actresses and socialites, the regrettable collagen sins committed by Melanie Griffith and Meg Ryan. Why do some wrinkles prompt people to seek surgery and others trouble them hardly all? What does the topography of a face say about a person? Why do we shun the lines we shun, and why do we keep the lines we keep?

Click here for a slide show on the aesthetics of wrinkles.