Task 5 - Genetics and Evolution Flashcards
Additive & non-additive genetic influences
ADDITIVE
each gene contributes to one factor, so combined effect of genes can be estimated by adding together separate effects
combined effects of two or more genes on personality are vary simple, each gene contributes separately to level of trait
NON-ADDITIVE (MULTIPLICATIVE GENETIC EFFECTS)
more complex interaction between genes
expression of gene A depends on presence of gene B
Identical twin have same genes –> they are both eqally influenced by nonadditive genes, which increases similarity
Fraternal twins share less genes –> they can be independently influenced by nonadditive genes
when nonadditive genetic influences on a trait are important, identical twins will be twice as similar as fraternal twins –> tells us that nonadditive genetic influences are involved
Genotype - environment correlations
= your genetic tendencies might actually cause you to be exposed to some kinds of environments, more than other kinds, and the differences between those environments might then influence the development of your personality characterisitcs
three types:
1.PASSIVE GENOTYPE-ENVIRONMENT CORRELATION
children inherit combination of genes and environment “passively”, not as result of own behavior –> e.g.: parents like to read, so child has greater tendency to read, and parents expose kid to various books
- REACTIVE GENOTYPE-ENVIRONMENT CORRELATION
people’s reaction to child’s genetic tendencies end up influencing the environment that child experiences –> e.g.: reaction of people in kids’ environment make on talent to read fast, contributes to development of reading abilities - ACTIVE GENOTYPE-ENVIRONMENT CORRELATION
child actively chooses environments as function of his genetic predispositions –> e.g.: because of talent, they like to read a lot, which contributes to development of their abilities
Adaptive Trade-offs between high and low levels of the HEXACO personality factors
HONESTY-HUMILITY
belonging traits include sincerity, fairness, modesty, and lack of greed
common element: tendency to not exploit or take advantage of others
AGREEABLENESS
belonging traits include forgiveness, gentleness, flexibility and patience
tendency to continue cooperation with others who might have exploited in some way
EMOTIONALITY
belonging traits include fearfulness, anxiety, dependence and sentimentality
tendency to promote the survival of oneself and one’s kin
EXTRAVERSION
belonging traits include social self-esteem, social boldness, sociability, and liveliness
common element: tendency to engage actively in social endeavors
CONSCIENTIOUSNESS
belonging traits include organization, diligence, perfectionism and prudence/caution
common element: tendency to engage actively in task-related endeavor
OPENNESS TO EXPERIENCE
belonging traits include aesthetic appreciation, inquisitiveness, creativity and unconventionality
common element: tendency to engage actively in idea-related endeavors
Summary of theoretical interpretation of HEXACO personality factors
F= Factor I= interpretation B= benefits of high levels C= costs of high levels
F: Honesty-Humility
I: Reciprocal altruism (fairness)
B: Gains from cooperation (mutual help and nonaggression)
C: Low of potential gains resulting from exploitation of others
F:Agreeableness (versus Anger)
I: Reciprocal altruism (tolerance)
B: Gains from cooperation (mutual help and nonaggression)
C: Losses due to being exploited by others
F: Emotionality
I: Kind altruism
B: Survival of kin (especially offspring), personal survival (especially as favors kind survival)
C: Lows of potential gains associated with risks to self and kin
F: Extraversion
I: Engagement in social endeavors
B: Social gains (friends, mates, allies)
C: Energy and time, risks from social environment
F: Conscientiousness
I: Engagement in task-related endeavors
B: Material gains (improved use of resources, reduced risks)
C: Energy and time
F: Openness to experience
I: Engagement in idea-related endeavors
B: Material and social gains (resulting from discovery)
C: energy and time, risks from social and natural environment
Estimates of the Magnitude of Genetic Influence
Findings should not be considered as generalizable
PERSONALITY
Genetic influence in range of 40 to 50%, heritability is approximately the same
evidence of nonadditive genetic variance
Little evidence for significant shared environmental influence
MENTAL ABILITY
early in life, shared environmental factors are the dominant influence on IQ, but gradually genetic influence increases, with effects of shared environment dropping near to zero
Twin and adoption studies
PSYCHOLOGICAL INTERESTS
Heritabilities estimated using data gathered in a single large study
standard vocational interest questionnaire
Little variation in heritability: 0.36
Evidence for nonadditive genetic influence
evidence for shared environmental influence, although this influence is modest, about 10& for each trait
PSYCHIATRIC ILLNESSES
- Schizophrenia: high degree of genetic influence, mostly additive; no shared environmental influence
- Major depression: is less heritable than schizophrenia –> 0.40
- Panic disorder, anxiety and phobias: moderately heritable, few sex differences
- Alcoholism: heritability 0,5 to 0,6 ; mostly additive
- Antisocial behavior: genetic influence is additive and in the range of 0.41 to 0.46; shared environmental influences decrease from childhood to adulthood, but do not entirely disappear in adulthood
SOCIAL ATTITUDES
Conservatism correlates highly with right-wing authoritarianism: 0.72 –>moderately heritable
Religiousness is only slightly heritable
–>strongly influenced by shared environment: 0.6 in girls and 0.45 in boys; moderately heritable in adults; membership in a specific religious denomination is largely due to environmental factors
Different theories: How can evolutionary psychology explain personality?
LIFE-HISTORY THEORY
energy is finite so there are major compromises in an individual’s life with respect to capturing and allocating energy
–> Trade offs
Energy allocated toward reproduction includes all of the effort required to successfully select, attract and retain a mate
Example: Impulsivity: Adaptive strategy that uses a lot of energy in relatively short time, might be an adaptive strategy due to short life expectancy
COSTLY SIGNALING
Individuals compete with one another in sending signals to others about their quality as a mate or friend
those seen as highest quality have advantage in being chosen
social competitions provide incentives for deception
costly signal tends to be honest signal, but not everyone can afford it
–> e.g.: you cant be generous if you dont have enough money
can be linked to Life-History theory
–>a mate who cannot afford to produce high-quality signals as a short-term mate might shift to a life history strategy of heave investment in one long term committed mate-ship
BALANCING SELECTION
occurs when genetic variation is maintained by selection
–>different levels on a trait dimensions are favored in different environmental conditions to the same degree
2 Forms:
1. Environmental Heterogeneity in Fitness Optima: If selection pressures vary over time or space, then selection can favor different levels of personality trait in these different environments
2.Frequency Dependent Selection
Occurs when two or more strategies are maintained within population at a particular frequency relative to each other
Fitness of each strategy as is becomes more common
Personality differences appear most pronounced in social species, suggesting that it may be the social environment
MUTATION LOAD
Individuals differ in their mutation load
Heritability of some traits originates from individual differences in mutation load
–>can explain some harmful mental disorders
Can create relationship load: Y can disrupt the adaptive functioning of individuals unfortunate enough to have chosen them
CONTINGENT SHIFTS ACCORDING TO ENVIRONMENTAL AND PHENOTYPIC CONDITIONS
- Environmental heterogeneity in fitness optima: natural selection produces heritable individual differences
- -> different alleles are differentially selected within different environments
In terms of life history theory: when a man shifts into a more cautious, risk averse strategy after becoming father
In terms of costly signaling theory: when an environmentally contingent increase in mate value affords a greater ability to emit costly signals
- Situation-specific shifts: becoming more risk-taking during times of famine when food resources are low and require dangerous action to obtain
- Reactive heritability: shifts in response to one’s heritable phenotypic characteristics
Contingent shifts can occur in response to external environmental conditions
What explains Genetic Variation in Personality
The ideal conditions under which directional selection exhausts genetic variation do not exist. But in what ways?
1.NO SELECTION
unlikely, might apply to genes with no phenotypic expression
2.MUTATIONS
act as opposing evolutionary forces
Where there are no mutations, selection would eventually eliminate variability around the intermediate optimum
3.VARIABLE SELECTION
selection itself is variable, either spatially or temporally
-Spatial variability: results in mixing and variability
-Temporal variability: selection may never drive variance to zero or positively select new beneficial mutations more frequently
4.NEGATIVE FREQUENCY-DEPENDENT SELECTION
=A form of variable selection that exists only in specific situations
when it does, variant that are rare in the population tend to succeed, making multiple alleles persist stably
5.NON-ADDITIVITY
Genetic variance that in non-additive, at least with respect to its effect of fitness is not typically removed by selection
What accounts for genetic variation in personality?
Stabilizing selection against extremes
Some variation within extremes possibly maintained by variable selection
