title: Why do the well-fed appear to die young? A new evolutionary hypothesis for the effect of dietary restriction on lifespan.
abstract: Dietary restriction (DR) famously extends lifespan and reduces fecundity across a diverse range of species. A prominent hypothesis suggests that these life-history responses evolved as a survival-enhancing strategy whereby resources are redirected from reproduction to somatic maintenance, enabling organisms to weather periods of resource scarcity. We argue that this hypothesis is inconsistent with recent evidence and at odds with the ecology of natural populations. We consider a wealth of molecular, medical, and evolutionary research, and conclude that the lifespan extension effect of DR is likely to be a laboratory artifact: in contrast with captivity, most animals living in natural environments may fail to achieve lifespan extension under DR. What, then, is the evolutionary significance of the suite of responses that extend lifespan in the laboratory? We suggest that these responses represent a highly conserved nutrient recycling mechanism that enables organisms to maximize immediate reproductive output under conditions of resource scarcity.
authors.affiliation: University of New South Wales, Evolution and Ecology Research Centre and School of BEES, Sydney, New South Wales, Australia.
authors.forename: Margo I
authors.initials: MI
authors.lastname: Adler
authors.forename: Russell
authors.initials: R
authors.lastname: Bonduriansky
mesh_terms: D000818:Animals; D005075:Biological Evolution; D031204:Caloric Restriction; D005247:Feeding Behavior / Q000502:physiology*; D008136:Longevity / Q000502:physiology*; D008954:Models, Biological
keywords: aging; autophagy; caloric restriction; dietary restriction; lifespan extension; reproduction; somatic maintenance