Abstract
Biogerontologists and demographers have argued that the fastest, most cost-effective strategies for prevention of the medical problems that afflict those older than 60 years are likely to emerge from a deeper understanding of what factors time the aging process and how aging leads, in rough synchrony, to the many diseases and disabilities of aging. Biologists can support and refine this discussion by studies of slow-aging mice, of mice with disease-promoting mutations, of mice in which specific cellular responses have been abrogated by genetic or pharmaceutical interventions, of slow-aging dog and horse breeds, and of the factors, genetic and physiological, that coordinate lethal and nonlethal consequences of aging in people. More work is also needed to learn how timing of antiaging interventions can be used to optimize the balance between beneficial and undesirable effects.