The most common risk factor for serious disease is old age. Heart disease, cancer, stroke, neurological conditions, diabetes — all increase radically with advancing years. And the older a person is, the more likely he or she is to have multiple chronic illnesses.
Some scientists hope one day to treat all of them at once — by targeting aging itself.
Humans aren’t built to last forever. The oldest person on record was Jeanne Calment, a Frenchwoman, who died in 1997 at the age of 122. In 2040, the average life span for people in Spain, projected to pass Japan as the country with the longest-lived citizens, will reach about 86 years.
There is considerable dispute, however, over how long humans might live under optimal circumstances. In 2016, a team of scientists declared the upper limit to be 115 years. But in June, researchers reviewing death rates among elderly Italians suggested that there may be no limit at all.