The Evolution of Personality Victoria Thomas Psyc 3906

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

Variation Exists Because… There is a normal variation around an optimum There is a normal variation around an optimum The optimum value changes over time The optimum value changes over time Frequency dependent selection will play a role Frequency dependent selection will play a role

Why Does Variation Exist The ultimate source of variation is mutation 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 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 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 Therefore a trait that is affected by many genes will have a significant amount of genetic variation

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

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

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

Extraversion Positively related to number of sexual partners (reproductive success) Positively related to number of sexual partners (reproductive success) More extramarital affairs More extramarital affairs Higher sensation seeking behaviour Higher sensation seeking behaviour Initiate more social behaviour Initiate more social behaviour More physically active More physically active Undertake more exploration of their environment Undertake more exploration of their environment Higher rates of accident and illness hospitalization Higher rates of accident and illness hospitalization Suffer more from traumatic injury Suffer more from traumatic injury More related to criminal and antisocial behaviour More related to criminal and antisocial behaviour Higher rates of risk in general Higher rates of risk in general Expose their children more to step-parenting (which is a risk factor for the children) Expose their children more to step-parenting (which is a risk factor for the children) Benefits Costs

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

Neuroticism Positively correlated with competitiveness Positively correlated with competitiveness Academic success is positively correlated since they are more resilient Academic success is positively correlated since they are more resilient Intelligence is positively correlated with neuroticism Intelligence is positively correlated with neuroticism Intelligence has been mentioned as a personality trait however it is not part of the Big Five Intelligence has been mentioned as a personality trait however it is not part of the Big Five High levels of anxiety, depression and schizophrenia High levels of anxiety, depression and schizophrenia Low neuroticism has a fitness disadvantage because they lack motivational striving and hazard avoidance 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 Higher levels of risk taking and therefore higher risk of death Mount Everest Climbers had high levels of neuroticism Benefits Costs

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

Openness Openness is positively correlated to creativity Openness is positively correlated to creativity Females find creativity in a mate important Females find creativity in a mate important Better at thinking in abstract form Better at thinking in abstract form Increased level of schizophrenia Increased level of schizophrenia Associated with depression and psychotic delusions Associated with depression and psychotic delusions Benefits Costs

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

Conscientiousness Better plan ahead and has a positive life expectancy Better plan ahead and has a positive life expectancy High levels of risky behaviour avoidance High levels of risky behaviour avoidance Healthy behaviours Healthy behaviours High levels of delinquency and antisocial behaviour High levels of delinquency and antisocial behaviour High levels of self- control lead to missed opportunities High levels of self- control lead to missed opportunities Obsessive behaviours have been linked to high level of conscientiousness Obsessive behaviours have been linked to high level of conscientiousness Benefits Costs

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

Agreeableness Live more harmonious lives Live more harmonious lives Avoid violence and interpersonal hostility Avoid violence and interpersonal hostility Low levels of agreeableness increase fitness when they are few in numbers Low levels of agreeableness increase fitness when they are few in numbers Excessive trusting can lead to decreased fitness (reproduction levels) Excessive trusting can lead to decreased fitness (reproduction levels) They invest much of their energy into others and not themselves They invest much of their energy into others and not themselves Benefits Costs

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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