The Body: A Guide for Occupants

by Bill Bryson

There’s no question that people are living longer than ever. If you are a seventy-year-old man in America today, you have only a 2 per cent chance of dying in the next year. In 1940, that probability was reached at age fifty-six.3 In the developed world at large, 90 per cent of people reach their sixty-fifth birthday, the great majority of them in a healthy condition. But now it seems we have reached a point of diminishing returns. By one calculation, if we found a cure for all cancers tomorrow, it would add just 3.2 years to overall life expectancy.4 Eliminating every last form of heart disease would add only 5.5 years. That’s because people who die of these things tend to be old already, and if cancer or heart disease doesn’t get them, something else will. Of nothing is that more true than Alzheimer’s disease.5 Eradicating it altogether, according to the biologist Leonard Hayflick, would add just 19 days to life expectancy.