With theorists’ and their gloomy predictions cast in the shade, at least for the time being, experimental biologists are pushing confidently into the tangle of linkages that evolution has woven among food intake, fertility and life span. “My rule of thumb is to ignore the evolutionary biologists — they’re constantly telling you what you can’t think,” Gary Ruvkun of the Massachusetts General Hospital remarked this June after making an unusual discovery about longevity.

An important difference among experts on aging is whether there is an intrinsic rate of aging. Supposing there were cures for all diseases, what would one die of, if one died at all? <<