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EVOLUTIONARY BASES OF BEHAVIOR

EVOLUTIONARY BASES OF BEHAVIOR. DARWIN’S INSIGHTS. Wrote On the Origin of Species Identified natural selection as the mechanism that controls the process of evolution Attempted to discover why organisms developed traits that suited them for their environment. DARWIN. Noticed animals vary

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EVOLUTIONARY BASES OF BEHAVIOR

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  1. EVOLUTIONARY BASES OF BEHAVIOR

  2. DARWIN’S INSIGHTS • Wrote On the Origin of Species • Identified natural selection as the mechanism that controls the process of evolution • Attempted to discover why organisms developed traits that suited them for their environment

  3. DARWIN • Noticed animals vary • Noted some characteristics are heritable • Noted organisms reproduce at a pace that outdoes food supply and other resources • Therefore: traits that increase reproduction increase an organisms’ survivability

  4. EVOLUTIONARY THEORY • “Survival of the fittest” • Fitness: reproductive success of an individual organism relative to the avg reproductive success in the population • 2 ways traits contribute to evolution: • 1: survival advantage • 2: reproductive advantage

  5. NATURAL SELECTION • Def: heritable characteristics that provide a survival or reproductive advantage are more likely than alternative characteristics to be passed on to subsequent generations and thus they come to be “selected” over time

  6. CONTROVERSY • Went against idea of divine intervention in life • Implied humans are not unique and they share a common ancestry with other species

  7. REFINEMENTS • Theodore Dobzhansky synthesized Darwin’s theories with the genetics work of Gregor Mendel • Contemporary: gene pool shaped by genetic drift, mutations, and gene flow

  8. ADAPTATIONS • Def: inherited characteristic that increased in a population b/c it helped solve a problem of survival or reproduction during the time it emerged • Key product of evolution

  9. INCLUSIVE FITNESS • Def: the sum of an individual’s own reproductive success plus the effects the organism has on the reproductive success of related others • Explains paradox of self-sacrifice

  10. BEHAVIOR AS ADAPTIVE TRAITS • Patterns of behavior reflect evolutionary solutions to adaptive problems • Camouflaging, fleeing, selective reproduction

  11. PARENTAL INVESTMENT AND MATING SYSTEMS • Parental investment: what each sex has to invest—time, energy, survival risk—to produce and nurture offspring • Most males contribute little, females contribute the most

  12. POLYGYNY • When investment is high for females and low for males: • Polygyny: mating system in which each male seeks to mate w/ multiple females, whereas the female mates w/ only one male • Favors aggressively competitive males

  13. POLYANDRY • Def: mating system in which each female seeks to mate with multiple males, whereas each male mates w/ only one female • Very rare

  14. MONOGAMY • Def: mating system in which one male and one female mate exclusively (or almost) with each other

  15. MISCONCEPTIONS ABOUT EVOLUTION • 1: Evolution is only a theory---evidence to support is substantial • 2: Evolutionary analyses assume that organisms have a motive to max reproductive fitness • 3: Evolutionary analyses embrace genetic determinism

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