Rationale for Complex Programmed Life Span Regulation in Mammals

Arguments are presented suggesting that aging in mammals is the result of a complex life span regulation system that evolved because life span limitation produces direct evolutionary benefit. This concept, if valid and pursued, could have a significant effect on efforts to combat aging processes by providing additional targets for potential intervention. A complex life span regulation system implementing purposely programmed (adaptive) aging provides a better match to experimental evidence than the more popular nonprogrammed theories. The primary objection has historically been that adaptive aging is “impossible” because it is not supported by the mechanisms of the evolution process. This argument was once generally accepted. However, more recently a number of alternatives to classical evolutionary mechanics theory have been proposed that support purposely programmed aging. These alternatives were developed in response to observed issues other than aging and include group selection, kin selection, evolvability, and geneoriented evolutionary mechanics theories. This paper shows how one of the alternatives, evolvability theory, supports adaptive aging, and also presents arguments showing how evolvability theory can overcome specific objections put forward by proponents of classical evolutionary mechanics theory. The underlying issue, the evolutionary value of life as a function of age relative to reproductive maturity, has now endured unresolved for 150 years. Four different concepts still have adherents and each has corresponding dependent theories of biological aging. Lack of resolution is clearly interfering with efforts toward understanding aging and producing treatments for age-related conditions. Arguments are presented to the effect that many non-science factors, unique to this discipline, have acted to inhibit advances in this area.