title: Inclusive fitness effects can select for cancer suppression into old age.
abstract: Natural selection can favour health at youth or middle age (high reproductive value) over health at old age (low reproductive value). This means, all else being equal, selection for cancer suppression should dramatically drop after reproductive age. However, in species with significant parental investment, the capacity to enhance inclusive fitness may increase the reproductive value of older individuals or even those past reproductive age. Variation in parental investment levels could therefore contribute to variation in cancer susceptibility across species. In this article, we describe a simple model and framework for the evolution of cancer suppression with varying levels of parental investment and use this model to make testable predictions about variation in cancer suppression across species. This model can be extended to show that selection for cancer suppression is stronger in species with cooperative breeding systems and intergenerational transfers. We consider three cases that can select for cancer suppression into old age: (i) extended parental care that increases the survivorship of their offspring, (ii) grandparents contributing to higher fecundity of their children and (iii) cooperative breeding where helpers forgo reproduction or even survivorship to assist parents in having higher fecundity.
authors.affiliation: Department of Biological Sciences, Cancer Center, University of Illinois at Chicago, Chicago, IL 60612, USA Cancer Biology and Evolution Program, Moffitt Cancer Center, Tampa, FL 33612, USA.
authors.forename: Joel S
authors.initials: JS
authors.lastname: Brown
authors.affiliation: Department of Psychology, Center for Social Dynamics and Complexity, Center for Evolution and Medicine, Arizona State University, Tempe, AZ 85287-4501, USA Center for Evolution and Cancer, University of California San Francisco, San Francisco, CA 94143, USA aktipis@asu.edu.
authors.forename: C Athena
authors.initials: CA
authors.lastname: Aktipis
mesh_terms: D000375:Aging; D000818:Animals; D005075:Biological Evolution; D001947:Breeding; D003299:Cooperative Behavior; D005260:Female; D005298:Fertility; D056084:Genetic Fitness; D006801:Humans; D008297:Male; D008954:Models, Biological; D009369:Neoplasms / Q000209:etiology / Q000517:prevention & control*; D012098:Reproduction; D012641:Selection, Genetic
keywords: Peto's paradox; cooperative breeding; grandparenting; inclusive fitness; intergenerational transfers; parental investment