In the sixteenth century, Spanish explorer Ponce de León sought the “fountain of youth,” a source of water that could restore youth. While no such fountain has ever been found, many people—cognizant that aging is often associated with weakness and poor health—have tried to stymie the aging process.

There are several approaches to slowing down the aging process. Thirty thousand Americans take shots of estrogen, testosterone, or the human growth hormone, which strengthens the immune system and increases bone mass and muscle. Other options include exercise, eating healthier foods, reducing alcohol and tobacco use, and cosmetic surgery. Toby Mayer, the medical codirector of the Beverly Hills Institute of Aesthetic and Reconstructive Surgery, asserts that baby boomers have valid reasons for elective plastic surgery. According to Mayer, such surgery lets older Americans...