The secret to long life may be written in sequences of DNA that are short and sweet. After combing through genetic samples from hundreds of siblings over age 90, a team of Harvard physicians and molecular biologists say they are almost certain that the best way to ensure an exceptional old age is having the right one or two genes on chromosome 4.
"Most of us have the genetics to get us to our mid-to-late eighties in fine health, but we mess it up by smoking, not exercising, and eating a rotten diet," says aging specialist Tom Perls, who led the research team. "But only one in 10,000 seems to have the ability to reach 100, and they do this despite doing the same things as the rest of us." Moreover, these hardy few seem somehow to sidestep Alzheimer's disease, cancer, heart disease, and strokes.
Brief stretches of matching DNA on the fourth chromosome seem to be the most crucial genetic evidence linking the vigorous elders. Perls thinks the genes code for something that conveys increased resistance to age-related diseases, possibly by scooping up damage-causing free radicals or increasing the rate of DNA repair. Once they nail down the specific sequences, Perls and his colleagues will start looking at the related biochemical pathways and searching for drugs that mimic their effects. "We ought to be able to find a way to prevent the age-related diseases that kill most of us before our time," Perls says.