The Evolution of Personality

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The Evolution of Personality

• Victoria Thomas
• Psyc 3906

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Evolution of the Big Five

• Personality are individual differences that
  influence their cognitions, motivations, and
  behaviors in various situations
• Differences are Variations
• Evolution is gene variability

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Variation Exists Because

• There is a normal variation around an optimum
• The optimum value changes over time
• Frequency dependent selection will play a role

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Why Does Variation Exist

• The ultimate source of variation is mutation
• When a trait is influenced by a single gene the
  trait does not vary greatly since mutations arise
  relatively infrequently
• When a number of genes are involved in building a
  trait the selection does not remove them
  simultaneously
• Therefore a trait that is affected by many genes
  will have a significant amount of genetic
  variation

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Optimum Fitness Levels

• We talked about this in class
• Hawks and Doves
• Guppies and Prawns
• There must be costs and benefits to each of these
  traits
• The benefits must increase reproductive success
  when it exists in moderation
• The costs must also increase reproductive success
  when it exists in moderation

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Big Five Personality Traits

• The Big Five Personality Traits are classified
  into five categories
• Extraversion
• Neuroticism
• Openness
• Conscientiousness
• Agreeableness

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Extraversion

• This dimension is related to positive emotion,
  exploratory activity and reward.
• Its proximate basis is thought to involve
  variation in dopamine-mediated reward circuits in
  the brain

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Extraversion
Benefits Costs

• Higher rates of accident and illness
  hospitalization
• Suffer more from traumatic injury
• More related to criminal and antisocial behaviour
• Higher rates of risk in general
• Expose their children more to step-parenting
  (which is a risk factor for the children)

• Positively related to number of sexual partners
  (reproductive success)
• More extramarital affairs
• Higher sensation seeking behaviour
• Initiate more social behaviour
• More physically active
• Undertake more exploration of their environment

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Neuroticism

• This trait is associated with various activity
  levels and negative emotions
• Negative side effects are strong predictors of
  psychiatric disorders and impaired physical
  health
• It is a key predictor of relationship failure and
  social isolation

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Neuroticism
Benefits Costs

• Positively correlated with competitiveness
• Academic success is positively correlated since
  they are more resilient
• Intelligence is positively correlated with
  neuroticism
• Intelligence has been mentioned as a personality
  trait however it is not part of the Big Five

• High levels of anxiety, depression and
  schizophrenia
• Low neuroticism has a fitness disadvantage
  because they lack motivational striving and
  hazard avoidance
• Higher levels of risk taking and therefore higher
  risk of death
• Mount Everest Climbers had high levels of
  neuroticism

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Openness

• The Openness trait refers to openness to new
  experiences
• People who have high levels of openness believe
  more in paranormal activities and phenomena

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Openness
Benefits Costs

• Openness is positively correlated to creativity
• Females find creativity in a mate important
• Better at thinking in abstract form

• Increased level of schizophrenia
• Associated with depression and psychotic delusions

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Conscientiousness

• This trait involves a high level of order and
  self-control in pursuit of goals
• Immediate gratification is often delayed

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Conscientiousness
Benefits Costs

• Better plan ahead and has a positive life
  expectancy
• High levels of risky behaviour avoidance
• Healthy behaviours

• High levels of delinquency and antisocial
  behaviour
• High levels of self-control lead to missed
  opportunities
• Obsessive behaviours have been linked to high
  level of conscientiousness

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Agreeableness

• Related to high levels of empathy and trust
• Low levels of agreeableness are related to
  antisocial personality disorders

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Agreeableness
Benefits Costs

• Live more harmonious lives
• Avoid violence and interpersonal hostility
• Low levels of agreeableness increase fitness when
  they are few in numbers

• Excessive trusting can lead to decreased fitness
  (reproduction levels)
• They invest much of their energy into others and
  not themselves

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In Summation

• Fitness levels (reproductive success) are
  associated with both the costs and benefits of
  the Big Five Personality Factors
• Both sides (costs and benefits) of every trait
  (Extraversion, Neuroticism, Openness,
  Conscientiousness, Agreeableness) are beneficial
  when that trait is rare in the population in
  question.

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The End