Honor Hsin and Cynthia Kenyon, from the University of California at San Francisco, suggest in the journal Nature that sex cells in the gonads may play a key role in controlling how quickly a nematode grows old. Removing whole gonads had no effect but taking away embryonic cells that would have developed into the worm's sperm and eggs slowed the rate of ageing in adults.
The scientists believe the sex cells, or germ line, in the gonads monitor levels of reproduction and send out signals that cause the ageing of highly fertile worms. "The signalling system described here has the interesting effect of placing the ageing process partially under the control of the germ line."
Donald Riddle, a molecular biologist at the University of Missouri in Columbia, said there was a simple explanation: "Prolonged survival of the adult in response to limited food might improve its chances of reproducing."
Tom Kirkwood, professor of biological gerontology at Manchester University, said the finding fits in with the idea that animals which reproduce early in life are more likely to die prematurely.
But there is no evidence that humans, such as eunuchs, who have their sex organs removed in childhood live longer than normal, he said. "There is some suggestion that castrated male pets live longer but the evidence for the same being true in humans does not hold water. The numbers are just too small to see any effect."Reuse content