Biological Clock Theory of Aging

The biological clock theory of aging refers to the idea that aging is a biological function that serves an evolutionary purpose and is controlled by a biological clock or program similar to the one that controls other life-cycle functions like growth and reproduction. Programmed aging theories or adaptive aging theories (including clock theories) suggest that aging evolved because limiting individual lifespans beyond a species-specific age creates an evolutionary advantage for a population of those individuals by increasing the chance that the population will avoid extinction or increasing the chance that a species will produce descendant species. Programmed implies a function that is not only determined by the passage of time (clock) but may also be affected by other factors. For example, reproductive programs are typically synchronized to external cues such as seasons.

See longer summary of aging theories and their medical implications.