Mind you, C. elegans is a simple beast with a relatively small number of genes, and drawing conclusions about a genetic basis for human senescence is wildly risky. Nevertheless, the daffy-gened worm is a pioneer of out bioengineered future, a new Methuselah pushing the frontiers of life extending science. It has a front end and a back end, a mouth, a gut and an anus. They don't do much but wiggle, eat and reproduce. Now, some of them have twice as much time to do it.
Mutated worms produce slightly fewer offspring than normal worms.
One theory of aging postulates that the energy costs of reproduction shorten lifespan, and the California researchers wondered if the slight decrease in the brood size of mutated worms accounts for their longevity. To find out, they zapped the gonads of unmutated worms with a laser, putting an end to their fertility. These infertile worms lived no longer than usual. Apparently fecundity has no effect upon how long a worm survives. The mutated gene does indeed act as an on-off switch for postponing old age.