Personality psychology chapter6 genetics evolution and personality

Basic Approach of Biological Perspectives • Personality is genetically determined – Human behavioral tendencies arise from evolutionary processes • Human behavior is the product of a co

Chapter Six

Genetics, Evolution,

and Personality

Genetics, Evolution,

and Personality

Basic Approach of Biological Perspectives

• Personality is genetically determined

– Human behavioral tendencies arise from

evolutionary processes

• Human behavior is the product of a

complex biological organism

• Underlying genetics and biology influence processes in personality

Behavioral Genetics

• Key Methodologies

– Twin Studies:

Monozygotic Pairs Dizygotic Pairs Genetically identical Not identical CorrelationMZ CorrelationDZ

Difference x 2 = HERITABILITY

– Adoption Studies: How adopted children resemble…

Biological Parents Adopted Parents Genetically related Not related Correlation > Correlation

Inherited personality traits present at birth

• Genetically based

• Pervasive—affect how and what people do

• Three fundamental temperaments

– Activity level—overall output of behavior

– Sociability—preference for being with others

– Emotionality—ease of being emotionally aroused

• More recent views of temperaments

– Approach and avoidance

– Effortful control

Inheritance of Traits

• Evidence of heritability for a broad range

of traits

• Evidence for genetic component for all of the “big five” personality traits

Temperaments and the Big Five

Big Five Temperaments Neuroticism Emotionality

Extraversion Activity

Agreeableness Sociability

Openness Impulsivity

Conscientiousness Intelligence

(-)

Other Effects of Genetics

• Genetics work through personality to effect:

– Risk for divorce

– Experiencing a serious life event

– Levels of social support

– Peoples attitudes on various topics

• Important question: Are the effects of personality and genetics distinct?

Molecular Genetics

• Much of human genome does not vary from person to person

• Differences arise at locations where

patterns of DNA proteins vary

• Research has identified a gene location that relates to:

– Novelty seeking

– Reward pursuit

– Impulse vs constraint

Environmental Influences

• Environmental effects may be underestimated

– Judged as that which is not explained by genetics

– Some environmental and genetic effects may have shared influence on an outcome (e.g., intelligence)

– If shared variance is attributed to genetics, the

environmental effect is underestimated

• Environmental influences on personality operate primarily at the individual level

• Sources of non-shared environmental influences

– Peer, friends, social networks

– Complementary, but diverging, roles within families – Parental preference

• Social behaviors exist because they confer adaptive advantage

• Example: Altruism

– May confer a biological disadvantage at an individual level – May help others in the same gene pool survive and

reproduce (inclusive fitness)

– Predicts altruism to members of kinship group

– May form the evolutionary basis of cooperation

Study of the biological basis of human

social behavior

Genetic Similarity Theory

• An extension of the concept of altruism

• We are more attracted to strangers who

genetically resemble us

– Evidence?

• Sexually involved couples shared more genetic markers than randomly selected couples

• Couples with children shared more genetic markers than those without

• Male friend pairs share more markers than random pairs

– How detected?

• Similar facial, physical features

• Odor

• Cultural similarities

Mate Selection and Competition

Females Males

• Greater investment in

offspring • Less investment in offspring

• Generate fewer offspring • Can generate more offspring

• Choosier in mate selection • Less discriminating

• Wait for best male • Maximize sexual

opportunities

• Males = success objects • Females = sex objects

• Attract males with: • Attract females with:

Fertility, youth, fitness, beauty Wealth, power, status

Concerns according to evolutionary theory: Females Males

• Family support • Paternity

Jealousy results from:

Females Males

• Emotional bonds • Sexual infidelity

Other Gender Differences

• Females:

– Maximize

attractiveness

– Strategy used more if

husband has high

income

• Males:

– Spend money – Give in to wishes – Strategies used more

if wife is young or attractive

Young Male Syndrome

• May have evolutionary roots

• Manifest by posturing, risk behavior, or violence in response to sexual selection pressure

• Elicited by specific situations

– Single, unemployed, low-status (poor mating potential)

• Evidence

– Males more likely to commit murder

– Men in prime mating age commit more murders

– Most killings over status (“face”)

• Little focus from behavioral genetics

• Assessment from genes unlikely

– Behavior probably involves many genes – Ethical implications?

Behavior Genetics and Disorder

• Schizophrenia

– Rate of concordance in twins

• MZ = 50%

• DZ = 9%

• Bipolar Disorder

– Twin research suggests genetic contribution

– Possible links to specific chromosomes (in Amish)

• Alcohol Abuse

– Possible link to gene for dopamine

• Antisocial Behavior

– Higher concordance rates among MZ twins on

childhood behavior problems and adult crime

Another View of Behavior Problems

• Premise: Two evolutionary processes

influence behavior

– Biological evolution—slow

– Cultural evolution—much faster

• Problems arise when the behavioral

tendency from biological evolution conflicts with current cultural environment