Tests for the causal involvement of specific physiological mechanisms in the control of aging require evidence that these mechanisms can be used to increase longevity or reproductive lifespan. Selection for later reproduction in Drosophila has been shown to lead to increased longevity, as well as increased resistance to starvation and desiccation stresses. Selection for increased resistance to starvation and desiccation in Drosophila melanogaster is here shown to lead to increased longevity, indicating that alleles that increase stress resistance also may increase longevity. The responses of desiccation and starvation resistance to selection are partly independent of each other, indicating a multiplicity of physiological mechanisms involved in selectively postponed aging, and thus aging in general.