Mammal aging: Active and passive mechanisms and their medical implications

Abstract

This article compares two hypotheses regarding the mechanisms responsible for aging in humans and other mammals. In the passive mechanism, aging is the result of inadequacies in maintenance and repair functions that act to prevent or repair damage from fundamental deteriorative processes. In the active mechanism, a life span management system purposely limits life span by deactivating maintenance and repair processes beyond a species-specific age. As described here, the active mechanism provides a much better fit to observational evidence while the passive mechanism provides a much better fit to traditional evolutionary mechanics theory. However, there are many other observations that conflict with traditional theory and consequently a number of alternative evolutionary mechanics theories have been developed since 1962. Several of these alternatives support active life span management and aging theories providing a rationale for active life span management have been developed based on each of those alternatives. This issue is very important to our ability to treat age-related diseases and conditions. If indeed the passive mechanism is correct, then efforts should continue to be exerted to find treatments for each different manifestation of aging, independently of the others. If the active concept is valid it is clear that there are, in addition, substantial opportunities for finding agents that generally delay aging and simultaneously ameliorate multiple manifestations of aging. In the past, the evolutionary issues have been used as essentially the entire justification for summarily rejecting active theories. Given the public health considerations and the increasing number of issues surrounding evolutionary mechanics theory, this is no longer a reasonable or responsible path.