Evidence is presented in support of the hypothesis that P DNA element movement in somatic cells of Drosophila melanogaster induces genetic damage that significantly reduces lifespan. The lifespan of D. melanogaster males was significantly reduced by the somatic movement of a single P element in the presence of P[ry+ delta 2-3](99B) transposase. In addition, the P[ry+ SalI](89D) repressor of P[ry+ delta 2-3](99B) somatic transposase was observed to reduce the effect of P element movement on lifespan. Finally, the frequency of somatic-cell chromosome breakage was significantly increased in neuroblasts of males with somatically active P elements. These results show that lifespan in D. melanogaster is decreased with increased somatic genetic damage from DNA-element movement. Although this conclusion does not confirm that transposable element movement is a cause of natural senescence, this conclusion is clear evidence in support of a close relationship between somatic genetic damage and aging.