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Change and aging: senescence as an adaptation

Grant number: 11/19496-0
Support type:Regular Research Grants - Publications - Scientific article
Duration: December 01, 2011 - May 31, 2012
Field of knowledge:Interdisciplinary Subjects
Principal Investigator:André Cavalcanti Rocha Martins
Grantee:André Cavalcanti Rocha Martins
Home Institution: Escola de Artes, Ciências e Humanidades (EACH). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Understanding why we age is a long-lived open problem in evolutionary biology. Aging is prejudicial to the individual and evolutionary forces should prevent it, but many species show signs of senescence as individuals age. Here, I will propose a model for aging based on assumptions that are compatible with evolutionary theory: i) competition is between individuals; ii) there is some degree of locality, so quite often competition will be between parents and their progeny; iii) optimal conditions are not stationary, mutation helps each species to keep competitive. When conditions change, a senescent species can driveimmortal competitors to extinction. This counter-intuitive result arises from the pruning caused by the death of elder individuals. When there is change and mutation, each generation is slightly better adapted to the new conditions, but some older individuals survive by chance. Senescence can eliminate those fromthe genetic pool. Even though individual selection forces can sometimes win over group selection ones, it is not exactly the individual that is selected, but its lineage. While senescence damages the individuals and has an evolutionary cost, it has a benet of its own. It allows each lineage to adapt faster to changing conditions. We age because the world changes. (AU)