On page 2137, a research team reports the discovery of a gene that, when altered, can double the life-span of fruit flies and may one day offer the promise of perpetual youth. Preliminary data suggest that the protein encoded by this gene transports and recycles metabolic byproducts. The researchers think that defects in the gene can lead to production of a protein that renders metabolism less efficient; as a result the body functions as if the fruit fly were dieting, even though its eating habits are unchanged. The work may lead to a better understanding of how metabolism plays into aging.