L4/CH6/CH8 Flashcards
Nature vs nurture debate
whether genes or environment are more important in accounting for differences in a trait within the population (not an individual)
Heritability
proportion of observed variance in a group of individuals that can be explained or accounted for by genetic variance
3 characteristics of heritability
cannot be applied to an individual; not constant or absolute; not a precise statistic
Environmentality
proportion of observed variance in a group of individuals attributable to environmental variance
Twin studies
estimates heritability by gauging whether identical or MZ twins are more similar than fraternal or DZ twins
2 assumptions made in twin studies
equal environments and representativeness
Representativeness assumption
findings from twin research can be generalized to non-twin individuals
Adoption studies
correlations of adopted children with genetic parents give evidence of genetic influence while correlation with adoptive parents give evidence of environmental influence
Major strength of adoption studies
genetic parents provide no environmental influence so genes and environment aren’t confounding
Limitation of adoption studies
possible selective placement of adopted children with similar characteristics to the adoptive parents
Shared environmental effects
family and environmental influences that affect twins or siblings similarly
Non-shared environmental effects
family and environmental influences that affect twins or siblings differently
Aspects of a person a shared environment influences
attitudes, religious beliefs, political orientation, health behaviors (e.g. smoking and drinking tendencies)
3 types of interactions between genes and environment
genotype-environment interaction, genotype-environment correlation, epigenetics
Genotype-environment interaction
environment has a different impact depending on an individual’s genotype (e.g. abused children with low MAOA become antisocial and violent)
Genotype-environment correlation
exposure to environmental conditions depends on genotype
3 kinds of genotype-environment correlations
passive, reactive, and active
Passive genotype-environment correlation
the child is responsive to the environment provided by their parents based on their genes (i.e. parents provide both genes and environment to the children who did nothing to obtain that environment)
Reactive genotype-environment correlation
heritable behavior evokes different environmental/social responses
Active genotype-environment correlation
heritable propensity to select the kind of environment one exponses oneself to
Epigenetics
the study of changes in organisms caused by changes in gene expression due to environmental influences (i.e. how nurture shapes nature)
Behaviors with epigenetic effects
risk-taking behavior, anxiety, stress reactivity, sociability
2 candidate genes with direct links to personality
dopamine receptor gene DRD4 and serotonin transporter gene 5-HTTLPR
Behaviors linked to DRD4 gene
novelty-seeking and extraversion
Behaviors linked to 5-HTTLPR gene
neuroticism (associated with 9-level loci) and other depressive and anxiety-related traits
How can genes affect likelihood of divorce?
genes > neurotransmitters, hormones, physiological arousal > thoughts, feelings, behaviors over time > form traits that influence relationship
5 core personality traits found in chimpanzees
reactivity/undependability, dominance, openness, extraversion, agreeableness
2 major accomplishments of our ancestors that led to evolution
they survived to reproductive age and they reproduced
What 2 behaviors did our evolutionary success depend on?
getting ahead (agency) and getting along (communion)
2 goals people had to fulfill across time and culture
to engage with others THEN to pursue personal goals and distinctiveness
2 levels of analysis from an evolutionary perspective
human nature; individual and group differences
Human nature
a product of evolutionary processes: psychological mechanisms and traits that spread through the population and came to characterize all humans
4 traits that comprise human nature
the need to belong, empathy, helping/altruism, universal emotions
Adaptive functions of belonging in a group
resources (e.g. food), protection, and having a concentration of mates
Evolutionary benefits of empathy
social cohesion and cooperation
How does helping enhance the inclusive fitness of helpers?
helping others (typically those closely related like siblings) increases the their likelihood of survival and reproductive success
When do emotions have an evolutionary basis?
when they are shared by all members of a species
2 evolutionary functions of emotions
serve as adaptive psychosocial mechanisms that signal other individuals and can be used to manipulate others
What are the only primates that engage in lethal aggression and warfare?
humans and chimpanzees (due to low expression of ADRA2C gene which inhibits fight or flight)
4 leading explanations for the maintenance of individual differences over time
environmental triggers of differences, frequency-dependent selection of traits, contingencies among traits, optimal variance over time and space
Environmental triggers of differences
individual differences result from environmental differences acting on species-typical psychological mechanisms
Contingencies among traits
individual differences result from contingencies among traits (e.g. certain physical traits may make the expression of certain psychological traits more or less adaptive)
Frequency-dependent selection
reproductive success of a trait depends on its frequency relative to that of other traits in a population (e.g. more common = less competitive advantage)
Optimal variance over time and space
different levels of a trait are optimally adaptive in different environmental conditions over time
Balancing selection
recognition that the variability of a trait within a population is maintained on a genetic level (because no trait is adaptive across all environmental conditions)
