How is cellular senescence related to longevity determination?
Aging is a process that begins after puberty and results from increasing random systemic molecular disorder. This disorder has multiple causes, including damage by reactive oxygen species, also know as oxygen free radicals (see Oxidative Damage Research Center), but generally results from the gradual loss of the energy necessary to maintain molecular structure and function. On the other hand, longevity determination, or a species’ maximum life span, is not a random process. A species’ maximum longevity has been determined over time by natural selection. The survival of a species depends on a sufficient number of members living long enough to reproduce and, if necessary, to raise progeny to independence. Natural selection favors animals that have greater survival skills and, especially, redundant physiological reserve in vital organs beyond the minimum needed to survive the damage that might be exacted by predators, disease, accidents or environmental extremes. Physiological capacity be
