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Chapter 9

PSY 321 Chapter 9: Chapter 9

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PSY 321
Erica Nuss

Chapter 9:THE INHERITANCE OF PERSONALITY: Behavioral Genetics and Evolutionary Theory 1. Behavioral genetics: attempts to explain how individual differences in behavior—personality traits—are passed from parent to child and shared by biological relatives. 2. Evolutionary psychology: attempts to explain how patterns of behavior that characterize all humans originated in the survival value these characteristics provided over the history of the species. 3. Behavioral genetics 1) Personality trait: A pattern of behavior relevant to more than one situation 2) Controversy a. Eugenics: the belief that humanity could be improved through selective breeding b. Cloning: it might be technologically possible to produce a complete duplicate—psychological as well as physical—of a human being. c. Either eugenics or cloning turns out to be very feasible. Because personality is the result of a complex interaction between an individual’s genes and the environment 3) Calculating heritability a. Basic research: to compare similarities in personality between individuals who are and are not genetically related and are related to each other to different degrees b. Basic questions: the degrees to which variation in the phenotype can be attributed to variation in the genotype c. Look at twins d. Concentrates on the less than 1 percent of the human genome that varies e. Heritability coefficient: Conclusion: Heritability = 40%. f. The figures are average, doesn’t describe any of a particular pair: This point underlines the fact that behavioral genetic analyses and the statistics they produce refer to groups or populations, not individuals. g. As a result, in terms of genetic expression, fraternal siblings will be less than one-fourth as similar to each other, on average, as identical twins instead of half as similar. 4) What heritabilities tell you a. Genes matter. Not all of personality comes form experience, some of it comes form genes b. Insight into etiology: severe mental retardation is not heritable. c. Insight into environment: it provides a window into how the early environment does—or does not—operate in shaping personality development. 5) Does family matter? A recent major meta-analysis that summarized the results of many studies concluded that the shared family environment was important in the development of many forms of psychopathology between childhood and adolescence, including conduct disorder, rebelliousness, anxiety, and depression. The only exception was attention deficit hyperactivity disorder (ADHD), for which the shared family environment did not seem to matter—this outcome might be more directly under the control of genes. 6) Nature and Nurture a. The less a trait varies across individuals, the lower its heritability is likely to be. b. If a given trait has a high heritability, two situations are possible: The trait might vary greatly across individuals, or it might be a trait that is determined largely by genes. 7) How genes affect personality a. Molecular genetics. - Association method: tries to determine whether differences in a trait correlate with differences in a particular gene across individuals. - Examples: The genetic basis of homosexuality in males: X chromosomes they shared - Traits associated with behavioral and emotional control and a gene called DRD4, which affects the development of dopamine receptors. • Dopamine is part of the brain system that responds to reward • Different forms of the DRD4 gene are associated with variations in sensation seeking, and so concluded that this gene might be a basis of sensation seeking via its effect on dopaminergic systems - A shortage of serotonin has been blamed for a wide variety of emotional disorders ranging from depression to anxiety and social phobia, and that drugs (such as SSRIs) that increase the level of serotonin in the brain effectively treat these disorders, at least sometimes. The 5-HTT gene, associated with a serotonin transporter protein, has two variants, or alleles. • People with the short allele score higher on measures of neuroticism • The amygdala in people with the short allele also shows stronger responses to viewing fearful and unpleasant stimuli such as pictures of frightened- looking faces, accident victims, mutilated bodies, and polluted scenery • The prevalence of the short allele of the 5-HTT gene may vary across cultural groups. • Some writers have speculated that it may be one reason why Asian cultures emphasize cooperation and avoiding conflict over the kind of individualistic striving said to be characteristic of Western cultures - They do not apply to everybody b. Gene-environment interaction - Basic principle: genes influence the development of behavior only in people who live in some kind of environment - Genes affect personality (shorter and was teased) - People choose their environment due to genes - The same environment can affect individuals in different ways - Epigenetics: how experience, especially early in life, can determine how or even whether a gene is expressed during development 8) The future of behavioral genetics a. The genome-wide association (GWA) study: require exploring for the genes that are associated with personality using techniques b. This is very difficult and expensive technique 4. Evolutionary personality psychology 1) Evolutionary theory is the foundation of modern biology. 2) One landmark book, E. O. Wilson’s Sociobiology: The New Synthesis (1975), applied evolutionary theory to psychology and sociology. 3) Evolution and behavior a. The more a behavioral tendency helps an individual to survive and reproduce, the more likely the tendency will appear in subsequent generations. b. The approach is to is to identify a common behavior pattern and then ask how it might have been adaptive (beneficial to survival and reproduction) for the human species across the millennia c. Aggression and altruism - A tendency to be aggressive can help a person to protect territory, property, and mates, and also lead to dominance in the social group and higher status. - A tendency to aid and protect other people, especially close relatives, might help ensure the survival of one’s own genes into succeeding generations, an outcome called inclusive fitness. d. Self-esteem - all of us—are the descendants of people who cared deeply what other people thought about them. e. Depression - crying may often be a useful way of seeking social support, and that fatigue and pessimism can prevent one from wasting energy and resources on fruitless endeavors. f. Mating behavior - Differences between mate selection (attraction), and mating strategies - Sociosexuality • Definition: the willingness to engage in sexual relations in the absence of a serious relationship • Men score higher • Both men and women who score high are interested in the physical attractiveness and social visibility of potential partners, those score lower foucs more on personal qualities and their potential to be good parents - Jealousy • Men- not the biologically father • Women- the man is not emotional bonded with her • “sexy son” theory 5. Individual differences 1) The mechanism of evolution requires individual differences to be maintained. For a species to remain viable, it must include diversity 2) Evolutionary psychology accounts for individual differences in three additional ways a. Behavioral patterns evolve as reactions to particular environmental experiences. b. People have several behavioral strategies, but they use the one
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