Abstract

In the 60 years since Medawar questioned the assumption that aging is a selected trait with a fitness benefit, mainstream biogerontology has overwhelmingly adopted the view that aging is a product of evolutionary neglect rather than evolutionary intent. Recently, however, this question has come to merit further scrutiny, for three reasons: a variety of new ways in which aging could indeed be “programmed” have been proposed, several phenomena with superficial similarities to programmed aging have been suggested to offer evidence for it and against the mainstream consensus, and above all it has become appreciated that the existence or otherwise of “pro-aging genes” has enormous implications for determining our optimal strategy for the medical postponement of age-related ill-health. Accordingly, it is timely to revisit the arguments and data on this topic. In this article I discuss difficulties in reconciling the programmed-aging concept with existing data, flaws in various arguments given by others that existing data prove aging to be programmed, and extensions of these considerations to various phenomena that in one or another way resemble programmed aging. I conclude that, however much we might wish that aging were programmed and thus that the ill-health of old age could be greatly postponed just by disabling some aspect of our genetic makeup, the unfortunate truth is that no such program exists, and thus that our only option for substantial extension of healthspan is a divide-and-conquer panel of interventions to repair the damage that the body inflicts upon itself throughout life as side-effects of its normal operation. I explicitly avoid arguments that rely on unnecessarily abstruse evolutionary theory, in order to render my line of reasoning accessible to the broadest possible audience.

Keywords: Programmed aging, mutation/selection balance, antagonistic pleiotropy, negligible senescence.