Still, researchers caution that aspiring centenarians shouldn't write off healthy lifestyle choices as a wasted effort. "Certainly having Mercedes-Benz genes helps, but there's a myth out there that living to 100 is entirely genetic," says Bradley Willcox, a longevity researcher based in Hawaii. He's the medical director of the longest-running centenarian study in the world, which has followed Okinawan centenarians since 1975, as well as a Hawaii-based study of long-lived Japanese-American men.
While Willcox's group has shown that having a long-lived mother doubles a man's likelihood of hitting 100—underscoring that there must be a genetic component to longevity—not smoking ups the odds by seven times. Being lean, married, and avoiding alcohol all seem to help. "Lifestyle choices are absolutely critical, especially if you're stuck with Ford Escort genes like most of us are," says Willcox. Research suggest that lifestyle choices account for about 75 to 80 percent of longevity, with genetics being responsible for the rest.
Some of the best news that has emerged from research on centenarians is that being extremely old doesn't necessarily mean being extremely disabled. About 15 percent of people have no signs of age-related disease at 100 years and 43 percent have no signs of disease until 80. "It's not the older you get, the sicker you get," says Perls. "What we see is that the older you get, the healthier you've been."
Corrected on 5/11/2012: An earlier version of this story misspelled the name of Nir Barzilai, director of the Institute for Aging Research at Albert Einstein College of Medicine.