The Evolution of PersonalityThe Evolution of Personality

Victoria ThomasVictoria ThomasPsyc 3906Psyc 3906

Evolution of the Big FiveEvolution of the Big Five

Personality are individual differences that Personality are individual differences that influence their cognitions, motivations, and influence their cognitions, motivations, and behaviors in various situations behaviors in various situations

Differences are VariationsDifferences are VariationsEvolution is gene variabilityEvolution is gene variability

Variation Exists Because…Variation Exists Because…

There is a normal variation around an There is a normal variation around an optimum optimum

The optimum value changes over timeThe optimum value changes over timeFrequency dependent selection will play a Frequency dependent selection will play a

rolerole

Why Does Variation ExistWhy Does Variation Exist

The ultimate source of variation is mutationThe ultimate source of variation is mutation When a trait is influenced by a single gene the trait When a trait is influenced by a single gene the trait

does not vary greatly since mutations arise relatively does not vary greatly since mutations arise relatively infrequentlyinfrequently

When a number of genes are involved in building a When a number of genes are involved in building a trait the selection does not remove them trait the selection does not remove them simultaneouslysimultaneously

Therefore a trait that is affected by many genes will Therefore a trait that is affected by many genes will have a significant amount of genetic variationhave a significant amount of genetic variation

Optimum Fitness LevelsOptimum Fitness Levels

We talked about this in classWe talked about this in class Hawks and DovesHawks and Doves Guppies and PrawnsGuppies and Prawns

There must be costs and benefits to each of There must be costs and benefits to each of these traitsthese traits

The benefits must increase reproductive The benefits must increase reproductive success when it exists in moderationsuccess when it exists in moderation

The costs must also increase reproductive The costs must also increase reproductive success when it exists in moderationsuccess when it exists in moderation

Big Five Personality TraitsBig Five Personality Traits

The The Big Five Personality TraitsBig Five Personality Traits are are classified into five categoriesclassified into five categoriesExtraversionExtraversionNeuroticismNeuroticismOpennessOpennessConscientiousnessConscientiousnessAgreeablenessAgreeableness

ExtraversionExtraversion

This dimension is related to positive This dimension is related to positive emotion, exploratory activity and reward.emotion, exploratory activity and reward.

Its proximate basis is thought to involve Its proximate basis is thought to involve variation in dopamine-mediated reward variation in dopamine-mediated reward circuits in the braincircuits in the brain

ExtraversionExtraversion

Positively related to Positively related to number of sexual number of sexual partners (reproductive partners (reproductive success)success)

More extramarital affairsMore extramarital affairs Higher sensation seeking Higher sensation seeking

behaviourbehaviour Initiate more social Initiate more social

behaviourbehaviour More physically activeMore physically active Undertake more Undertake more

exploration of their exploration of their environmentenvironment

Higher rates of accident Higher rates of accident and illness hospitalizationand illness hospitalization

Suffer more from Suffer more from traumatic injurytraumatic injury

More related to criminal More related to criminal and antisocial behaviourand antisocial behaviour

Higher rates of risk in Higher rates of risk in generalgeneral

Expose their children Expose their children more to step-parenting more to step-parenting (which is a risk factor for (which is a risk factor for the children)the children)

Benefits Costs

NeuroticismNeuroticism

This trait is associated with various activity This trait is associated with various activity levels and negative emotionslevels and negative emotions

Negative side effects are strong predictors Negative side effects are strong predictors of psychiatric disorders and impaired of psychiatric disorders and impaired physical healthphysical health

It is a key predictor of relationship failure It is a key predictor of relationship failure and social isolationand social isolation

NeuroticismNeuroticism

Positively correlated with Positively correlated with competitivenesscompetitiveness

Academic success is Academic success is positively correlated since positively correlated since they are more resilient they are more resilient

Intelligence is positively Intelligence is positively correlated with correlated with neuroticismneuroticism Intelligence has been Intelligence has been

mentioned as a personality mentioned as a personality trait however it is not part trait however it is not part of the Big Fiveof the Big Five

High levels of anxiety, High levels of anxiety, depression and depression and schizophreniaschizophrenia

Low neuroticism has a Low neuroticism has a fitness disadvantage fitness disadvantage because they lack because they lack motivational striving and motivational striving and hazard avoidancehazard avoidance

Higher levels of risk Higher levels of risk taking and therefore taking and therefore higher risk of deathhigher risk of death Mount Everest Climbers Mount Everest Climbers

had high levels of had high levels of neuroticismneuroticism

Benefits Costs

OpennessOpenness

The Openness trait refers to openness to The Openness trait refers to openness to new experiencesnew experiences

People who have high levels of openness People who have high levels of openness believe more in paranormal activities and believe more in paranormal activities and phenomenaphenomena

OpennessOpenness

Openness is Openness is positively correlated positively correlated to creativityto creativity Females find creativity Females find creativity

in a mate importantin a mate important

Better at thinking in Better at thinking in abstract formabstract form

Increased level of Increased level of schizophreniaschizophrenia

Associated with Associated with depression and depression and psychotic delusionspsychotic delusions

Benefits Costs

ConscientiousnessConscientiousness

This trait involves a high level of order and This trait involves a high level of order and self-control in pursuit of goalsself-control in pursuit of goals

Immediate gratification is often delayedImmediate gratification is often delayed

ConscientiousnessConscientiousness

Better plan ahead and Better plan ahead and has a positive life has a positive life expectancyexpectancy

High levels of risky High levels of risky behaviour avoidancebehaviour avoidance

Healthy behavioursHealthy behaviours

High levels of High levels of delinquency and delinquency and antisocial behaviourantisocial behaviour

High levels of self-High levels of self-control lead to missed control lead to missed opportunitiesopportunities

Obsessive behaviours Obsessive behaviours have been linked to have been linked to high level of high level of conscientiousnessconscientiousness

Benefits Costs

AgreeablenessAgreeableness

Related to high levels of empathy and trustRelated to high levels of empathy and trustLow levels of agreeableness are related to Low levels of agreeableness are related to

antisocial personality disordersantisocial personality disorders

AgreeablenessAgreeableness

Live more Live more harmonious livesharmonious lives

Avoid violence and Avoid violence and interpersonal hostilityinterpersonal hostility

Low levels of Low levels of agreeableness agreeableness increase fitness when increase fitness when they are few in they are few in numbersnumbers

Excessive trusting Excessive trusting can lead to decreased can lead to decreased fitness (reproduction fitness (reproduction levels)levels)

They invest much of They invest much of their energy into their energy into others and not others and not themselvesthemselves

Benefits Costs

In SummationIn Summation

Fitness levels Fitness levels (reproductive success)(reproductive success) are associated are associated with both the costs and benefits of the Big with both the costs and benefits of the Big Five Personality FactorsFive Personality Factors

Both sides Both sides (costs and benefits)(costs and benefits) of every trait of every trait (Extraversion, Neuroticism, Openness, Conscientiousness, (Extraversion, Neuroticism, Openness, Conscientiousness,

Agreeableness) Agreeableness) are beneficial when that trait is are beneficial when that trait is rare in the population in question.rare in the population in question.

The EndThe End