Richard Walker has been trying to conquer aging since he was a 26-year-old free-loving hippie. It was the 1960s, an era marked by youth: Vietnam War protests, psychedelic drugs, sexual revolutions. The young Walker relished the culture of exultation, of joie de vivre, and yet was also acutely aware of its passing. He was haunted by the knowledge that aging would eventually steal away his vitality—that with each passing day his body was slightly less robust, slightly more decayed. One evening he went for a drive in his convertible and vowed that by his 40th birthday, he would find a cure for aging.
Walker became a scientist to understand why he was mortal. "Certainly it wasn't due to original sin and punishment by God, as I was taught by nuns in catechism," he says. "No, it was the result of a biological process, and therefore is controlled by a mechanism that we can understand."
Medical science has already stretched the average human lifespan. Because of public health programs and treatments for infectious diseases, the number of people over age 60 has doubled since 1980. By 2050, the over-60 set is expected to number 2 billion, or 22 percent of the world's population. But this leads to a new problem: more people are living long enough to get chronic and degenerative conditions. Age is one of the strongest risk factors for heart disease, stroke, macular degeneration, dementia, and cancer. For adults in high-income nations, that means age is the biggest risk factor for death.