Diet can change the rate of aging in fruit flies, even reversing the normal longevity advantage of females over males, according to a population study by researchers at the University of California, Davis.
The results support earlier findings by the same scientists indicating that life span is not necessarily fixed for all animals, as had been presumed for years by many gerontologists.
Fast-breeding Medflies are used as models to study basic population questions. The newly published study provides a statistical analysis of the life span of more than 400,000 Mediterranean fruit flies. It was conducted by UC Davis statistics professor Hans-George Müller and entomology professor James Carey and will appear in the March 18 issue of the Proceedings of the National Academy of Sciences.
"This is the first known study to demonstrate that the age trajectory, or path of mortality, during a specific period of life can be changed by manipulating environmental conditions, in this case through diet," said Carey, an authority on insect demography, who for several years has used the Medfly to study life-span theories. "It was previously thought that the mortality curves for most species were more-or-less genetically predetermined."
Medflies usually live for about two to three weeks. Those that make it to 60 days have lived the equivalent of 85 human years. If they receive a normal diet of sugar plus protein, females generally outlive males by about 1.5 days. But in this new study, the researchers report that, when fed a protein-deprived diet, males lived shorter lives overall, but outlived females by a little more than two days.
Carey and colleagues conducted this nutrition-manipulation study to determine
why death rates level off sooner and at a lower level for female Medflies
than for their male counterparts. This earlier flattening of the female
mortality curve was observed in protein-deprived medflies studied in the
Contact: Patricia Bailey
University of California - Davis