Theories of Biological Aging

The complexity of the aging process diminishes the probability that any one theory would satisfactorily explain aging. The concept that some age-related changes may be programmed, whereas others are stochastic and unpredictable, is now generally accepted. However, some theories include both kinds of changes and are impossible to classify as one or the other. In fact, experts probably would not even agree on a common list of aging theories, so the following list should not be regarded as definitive or exhaustive. A further complication is the need to distinguish between the aging process itself and the effects due to phenomena such as diseases. A detailed discussion of various theories can be found in Modern Biological Theories of Aging (Warner et al., eds.).