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Evolution of Aging and Late Life Chapter 18 Experimental Evolution Does aging have a purpose? Is it adaptive? What is aging? Think-Pair-Share Does natural selection act on aging? Does aging evolve? What is aging to an evolutionary biologist? Think-Pair-Share We used to think… …aging evolved to eliminate older individuals to make way for the young. Why is this false? Think-Pair-Share What are the EVOLUTIONARY THEORIES OF AGING? Hamilton’s Forces of Natural Selection The force of natural selection acting on survival falls with adult age. If natural selection isn’t acting on aging, does aging evolve? How can we test theories of aging? If Aging has evolutionary basis 1.) Early reproduction will accelerate aging in population. 2.) Late reproduction will slow aging in population. • Well established laboratory organism • Used in experimental evolution studies • Short life-span • Easy to manipulate Model Organism Drosophila melanogaster Results show aging is evolutionary Drosophila melanogaster LATE LIFE How many life stages do you see represented in this graph? Think-Pair-Share What explains extreme old age? Discovery of Late Life • An evolutionarily distinct phase of life • Evolves with different rules than those of early life and aging.
