Sex-specific effects of interventions that extend fly life span.

Genetic and environmental interventions that extend life span are a current focus in research on the biology of aging. Most of this work has focused on differences among genotypes and species. A recent study on fruit flies shows that life span extension because of dietary restriction can be highly sex-specific. Here we review the literature on sex-specific effects of 56 genetic and 41 environmental interventions that extend life span in Drosophila melanogaster. We found that only one-sixth of the experiments provided statistical tests of differences in response between males and females, suggesting that sex-specific effects have been largely ignored. When measured, the life span extension was female-biased in 8 of 16 cases, male-biased in 5 of 16 cases, and not significantly different in only 3 of 16 cases. We discuss possible explanations for the sex-specific differences and suggest various ways in which we might test these hypotheses. We argue that understanding sex differences in the response to life span-extending manipulations should lead to new insights about the basic mechanisms that underlie the biology of aging in both sexes.