programmed aging theories contend that evolved biological mechanisms purposely limit internally determined
lifespans in mammals and are ultimately responsible for most instances of highly agerelated diseases and conditions. Until
recently, the existence of programmed aging mechanisms was considered theoretically impossible because it directly con
flicted with Darwin’s survivalofthefittest evolutionary mechanics concept as widely taught and generally understood.
However, subsequent discoveries, especially in genetics, have exposed issues with some details of Darwin’s theory that affect
the mechanics of the evolution process and strongly suggest that programmed aging mechanisms in humans and other mam
mals can and did evolve, and more generally, that a trait that benefits a population can evolve even if, like senescence, it is
adverse to individual members of the population.
Evolvability theories
contend that organisms can possess evolved design
characteristics (traits) that affect their ability to evolve, and further, that a trait that increases a population’s ability t
o evolve
(increases evolvability) can be acquired and retained even if it is adverse in traditional individual fitness terms. Programmed
aging theories based on evolvability contend that internally limiting lifespan in a speciesspecific manner creates an evolv
ability advantage that results in the evolution and retention of senescence. This issue is critical to medical research because
the different theories lead to dramatically different concepts regarding the nature of biological mechanisms behind highly
agerelated diseases and condition

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