Every organism has to deal with exposure to stresses.Animals have developed various strategies to cope with stress. It appears that the developed resistanceto stress is often related to longevity. Somescientists have advanced the hypothesis that thestress response may also counteract the negativeeffects of aging, and that exposing organisms to amild, sublethal stress, inducing a stress response,may help them to live longer. Several mild stresseshave been reported to increase longevity (irradiation,heat and cold shock, hypergravity, exercise, etc.), andone of them, hypergravity, to decrease the rate ofbehavioral aging. The mechanisms whereby thesestresses increase longevity have not yet been elucidated.However, the studies conducted so far show that theymay involve metabolic regulation and stress protein(hsps) induction.