What is aging? Evolutionary theory posits that it is the consequence of the accumulation of damage after the attainment of reproductive maturity, due to a weakening of the strength of natural selection in late life. This construct implies that aging represents disordered biology that is superimposed upon the living state. In this review, data collected across multiple species, including plants, strongly suggest that aging represents an evolved species-specific developmental program. Such a construct would account for the varied aging trajectories that can be observed across different species, each of which has its own characteristic pattern of aging. However, aging is a plastic developmental program and this plasticity accounts for the marked variation in aging trajectories observed across individuals within a single species; the result of environmentally induced epigenetic changes. Interventions directed at the plasticity of the aging process are the ones most likely to be successful in modifying this process.