An obscure group of animals may reveal the secret of elongating life

THE one sure way to prolong an animal’s life is, paradoxically, to starve it. “Caloric restriction”, as it is known in the trade, works for everything from threadworms to mammals (people included, as far as can be ascertained without the luxury of controlled experiments). So it is no surprise that it also works for a group of small creatures known as rotifers. If that were the only result of Shugo Watabe’s experiments on the critters, at the University of Tokyo, it would scarcely be worth reporting. What makes this news is that the offspring of the rotifers in question also lived longer than normal. And that—the inheritance of an acquired characteristic—is quite startling.

Rotifers are unusual in that they often reproduce by parthenogenesis (some species, indeed, can reproduce only in this way). A parthenogenetic population is, by definition, all female and the result, give or take the odd mutation, is that a rotifer’s daughters are genetically identical to her. That makes rotifers convenient subjects for studies of the controversial idea that characteristics acquired during an individual’s life can be passed down the generations in ways that are independent of mutations in the DNA. …