Psychology%20403:%20Topics%20in%20Evolutionary%20Psychology

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Psychology 403Topics in Evolutionary Psychology

• Dr. M.R. Snyder

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Evolutionary Psychology

• The approach
• Old application, new formalization

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Evolutionary Theories

• Why/how do new organisms develop?
• What drives change?

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Evolutionary Psychology

• Multidisciplinary approach
• About 20 years old as a formalized field
• Theoretical approach
• Cosimides Toobey (1992)
• Evolutionary Psychology Manifesto

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Evolutionary Theories Not New

• Greeks
• Heraclitus (6th C. BC)
• State of flux
• Aristotle (4th C. BC)
• Development in prescribed direction
• Medieval Europe
• St. Thomas Aquinas (13th C)
• Human/lower animal differences

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Eighteenth Century

• George Leclerc, Comte de Buffon
• Adaptations to fit environment pressures
• Erasmus Darwin
• Role of sexual reproduction
• Jean de Lamarck
• Inheritance of acquired characteristics
• Georges Cuvier
• Catastrophism

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Charles Darwin

• Provided causal mechanism
• Voyage of the Beagle (1831-1836)
• On the Origin of Species (1859)
• Variation, inheritance, selection
• Artificial, natural, sexual
• Differential reproductive success

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Social Darwinism

• Late 19th century to present
• Directed, purposeful
• Teleological
• Political, social agenda

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Sociobiology

• E.O. Wilson
• Systematic study of the biological basis of
  social behaviour

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Evolutionary Psychology Issues

• Are humans unique animals?
• Gradual or sudden development?
• Modularity of mind, or general information
  processor?
• Environment of Evolutionary Adaptiveness (EEA)

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Approaches

• Evolutionary Psychology
• Will the real EP please step forward?
• Dual Inheritance Theory (DIT)
• Human Behavioural Ecology (HBE)

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Terms and Concepts
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Genetics

• Mendellian genetics
• Gene, alleles
• Particulate inheritance
• Dominant or recessive
• Homozygous or heterozygous
• Genotype and phenotype
• Polygenetic effects
• Interaction between genes and environment

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Darwinian Selection

• Adaptive, maladaptive, neutral
• Success
• Not number of offspring, but number of
  reproducing offspring
• Gene, individual, or group as level of selection?

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Natural Selection

• Survival value
• Predator/prey, environment, parasitism, etc.
• Survival of the fittest

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Sexual Selection

• Intrasexual selection
• Within a sex
• Intersexual selection
• Between sexes

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Genetic Diversity

• Heterozygosity
• Variability of offspring in the population
• Disease vector
• Sexual vs. asexual reproduction

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r Values

• Genetic relatedness
• Probability of having the same gene due to common
  ancestor
• r 1.0
• Self, identical twins
• r 0.5
• Parent and child, siblings
• r 0.25
• Grandparent and grandchild

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Inclusive Fitness

• William Hamilton
• Classical (direct) and indirect fitness
• Role of r values
• rBgtC
• Phenotype and genotype

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How to be Successful

• Increase classical fitness
• Increase inclusive fitness
• Quantity vs. quality tradeoff

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Male vs. Female Reproduction

• Energy investment
• Commonalities
• Differences

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Adaptationist Approach
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Traits

• An aspect of an organisms phenotype
• Physiological, behavioural

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Adaptations

• Process by which evolution modifies and generates
  traits that effect the spread of some genes over
  others
• The end product of the process i.e., the traits
  selected by the evolutionary process

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Spandrels

• Byproducts
• Not all traits are directly selected for
• These traits are linked to other traits that were
  adaptations

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Energy

• Finite
• Cost/benefit
• Energy budgets require trade-offs
• Expectation is that evolution selected for
  adaptations to energy budget that allows for
  maximization of fitness

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Identifying Adaptations

• Traits show special design if they perform a
  specific function well, and
• It is difficult to postulate an alternative
  evolutionary process that led to the trait except
  for selection for this function
• Inferential

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Attractiveness as an Adaptation

• Particular traits perceived as attractive by
  opposite sex
• Benefits individuals reproductive fitness
• Symons (1995) Beauty is in the adaptations of
  the beholder.

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Selection Benefits for Attractiveness

• Genetic and resource benefits
• Selection favoured those who possessed traits
  that predisposed them to mate with others who
  possessed traits that provided the benefits
• Sexually selected traits

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Cross Cultural Value

• Buss (1989) surveyed from 37 cultures world wide
• Value of physical attractiveness rated highly
• Industrial, first world
• Traditional (e.g., Ache of Paraguay, Shiwiar of
  Equador, etc.)
• Also, cross-cultural agreement on who is
  attractive

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Sexual Selection

• A feedback system
• One sex develops preference for trait
• If it increases differential reproductive
  success, preference for trait spreads to
  offspring
• Members of opposite sex that have the desired
  trait will also, therefore, spread the trait to
  their offspring

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Intrasexual Selection

• Competition between members of the same sex
• Usually, perceived as male-male
• Polygynous mating systems
• However, in humans both male and female
  intrasexual selection

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Intersexual Selection

• Choice between the sexes
• Sometimes called, female choice
• Reproductive costs generally more expensive for
  females (limiting reproductive resource)

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Mutual Mate Choice

• Seen in species where both sexes invest heavily
  in offspring
• Both sexes are selected to display desired traits
• Seen in humans across time and cultures

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Signaling Quality Traits

• Traits that indicate something about an
  individuals fitness
• Honest signals are costly (Zahavi 1975)
• Handicap principle
• If you can afford the handicap, you must be of
  superior quality

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Sensory Bias

• May be a bias towards some trait in sensory
  system
• May have nothing to do with mate choice
• However, may inadvertently influence mate
  selection
• Genes for some trait may be piggybacked into
  gene pool due to genes for sensory bias