Eating less can lengthen an animal’s life. But now it seems that — for flies at least — they don’t have to actually cut down on the calories to benefit. Fruitflies can boost their lifespan just by not smelling their food. The result suggests that flies might use their sense of smell — as well as the actual consumption of food — to help determine how rich their environment is, and how they should go about distributing their energy resources.
From flies and worms to rats and mice, animals fed on restricted diets generally live longer than those given abundant food. No one is sure exactly why this is. One theory is that when times are tough and there is little food about, animals channel more of their resources into maintaining their everyday body function, at the expense of putting energy into reproducing. That can extend lifespan.