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Evolution of Aging & Late Life

Evolution of Aging & Late Life. Chapter 18. Evolutionary Definition of Aging. Sustained age-specific decline of fitness related characteristics not due to external environmental factors Not possible to study in vast majority of species in wild

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Evolution of Aging & Late Life

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  1. Evolution of Aging & Late Life • Chapter 18

  2. Evolutionary Definition of Aging • Sustained age-specific decline of fitness related characteristics not due to external environmental factors • Not possible to study in vast majority of species in wild • Based on Hamilton’s Mathematical Forces of Natural Selection.

  3. Population Genetic Hypothesis for Aging • Antagonistic Pleiotropy Evolutionary Trade-off, alleles with early benefit produce bad side effects later • Mutation Accumulation Decline of force of natural selection fails to remove deleterious mutations

  4. Role of Experimental Evolution in Aging If Aging has evolutionary basis- 1.) Early reproduction will accelerate aging in population. 2.) Late reproduction will slow aging in population.

  5. Results • Some experimental results consistent with Antagonistic Pleiotropy mechanism for evolution of aging • Other experiments support conclusion that Mutation Accumulation contributes to aging in Drosophila • Aging easily identifiable product of evolution involving many genes

  6. Discovery of Late Life • Studies of populations revealed that mortality rates increased exponentially during mid-life, plateau later. • Two theories- 1) Natural selection drops to zero after reproduction has ended 2) “Lifelong heterogeneity” differences in robustness of individuals

  7. Results • Late-life plateaus change with changes in end of reproductive age. 1) Antagonistic Pleiotropy possible genetic mechanism • No indication lifelong heterogeneity factor in Late-life plateaus

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