Long-lived recombinant inbred lines, some of which have mean and maximum life spans up to 70% longer than wild type, were used in these analyses. Longer life results from a slower exponential rate of increase in mortality. General motor activity decreases with chronological age in all genotypes; this decay in general motor activity is a biomarker of aging in that it is a predictor of maximum life span. The aging process has also been dissected into component processes. The length of development and the length of reproduction are unrelated to increased life span; lengthened life is due entirely to an increase in post-reproductive life span. Development, reproduction, and life span are each under independent genetic control. General motor activity and life span share at least one common rate-determining genetic component.