There is growing support for characterizing human aging from a life-course perspective, in terms of recognizing important influences operating from conception to death, and this approach provides a framework for understanding aging processes operating at the individual level. Kirkwood's disposable soma theory proposes that aging is a manifestation of imperfect somatic maintenance and repair processes. We can therefore predict that differing exposure to the determinants of somatic damage across the life-course, and variable capacity to respond in terms of repair are likely to underlie the wide variation in rates of aging between individuals.