Lecture 04 Nature, Nurture, Diversity

What is the Nature-NurtureDebate? What accounts for our behavioralproclivities, talents, abilities, personality,pre-dispositions, intelligence, temperament?Nature, Nurture, andHuman Diversity Are we born with these differences? (Nature) Or, do we acquire these differences from ourparents’ influence, societal influence, friends,etc? (Nurture)Chapter 41Nature, Nurture, and Human DiversityNature, Nurture, and Human DiversityEvolutionary Psychology: UnderstandingHuman NatureParents and peersCultural Influences Natural Selection Are all traits adaptive? An Evolutionary Explanation of Human Sexuality Males: healthy/fertile/nurturing mates Females: healthy/security/strengthPost-hoc? Promotes Status Quo (e.g., infidelity) Variations Across Cultures Culture and the Self Critiquing the Evolutionary Perspective 23Nature, Nurture, and Human Diversity Collectivistic IndividualisticCulture and Child-Rearing Protective Punitive Promote independence4Nature, Nurture, and Human Diversity Developmental Similarities AcrossGroupsGender Development The Nature of Gender Personality, language The Nurture of Gender Gender DevelopmentReflections on Natureand Nurture Gender roles Gender Similarities and Differences Aggression Social power Social connectedness561

Behavior Genetics: Predicting IndividualDifferencesNature, Nurture, and Human DiversitySimilaritiesDifferencesGenes: Same set ofchromosomesGenes: Genetic anomalies maymake us differentBiology: Organs and bodyfunctions sameBiology: May change duringdevelopmentBrain: Same brain architectureBrain: Asymmetry of brainacross gendersBehaviors: Speak languageBehavior: Speak differentlanguagesBehavior Geneticists study our differences andweigh the relative effects of heredity andenvironment.78Twin BiologyTwins and ProceduresStudying the effects of heredity and environment ontwo sets of twins, identical and fraternal, has come inhandy.Behavior geneticists’ effects of shared and uniqueenvironments on total or partial genetic makeup.910Twins Separated at BirthSeparated TwinsA number of studies compared identical twins raisedseparately from birth, or close thereafter, and foundnumerous similarities.Critics of separated twin studies note that suchsimilarities can be found between strangers.Researchers point out that differences betweenfraternal twins are greater than identical twins.Separated TwinsPersonality, IntelligenceAbilities, AttitudesInterests, FearsBrain Waves, Heart RateThe “James” Twins11122

Adoption StudiesAdoptive Studies Adoption studies, as opposed to twin studies,suggest that adoptees (who may be biologicallyunrelated) tend to be different from their adoptiveparents and siblings.Adoptive studies strongly point to the simple factthat biologically related children turn out to bedifferent in a family. So investigators ask: Personality vs. attitudes, values, religious viewsDo siblings have differing environmental experiences?Do siblings, despite sharing half of their genes, havedifferent combinations of the other half of their genes?Ultimate question: Does parenting have an effect?1314ParentingTemperament StudiesParenting does have an effect on biologically relatedand unrelated children, but not all.Temperament refers to a person’s stable emotionalreactivity and intensity. Identical twins expresssimilar temperaments, suggesting hereditypredisposes temperament.Parenting Influenceschildren’sAttitudes, ValuesManners, BeliefsFaith, Politics1516HeritabilityGroup DifferencesHeritability refers to the extent to which thedifferences among people are attributable to genes.If genetic influences help explain individualdiversity in traits, can the same be said about groupdifferences?Not necessarily. Individual differences in weight andheight are heritable and yet nutritional influenceshave made westerners heavier and taller than theirancestors were a century ago.17183

Nature and NurtureGene-Environment InteractionSome human traits are fixed, such as having twoeyes. However, most psychological traits are liableto change with environmental experience.Genes can influence traits which affect responses,and environment can affect gene activity.Genes provide choices for the organism to change itsform or traits when environmental variables change.Therefore, genes are pliable or self-regulating.19A genetic predisposition that makes a child restlessand hyperactive evokes an angry response from hisparents. A stressful environment can trigger genes tomanufacture neurotransmitters leading to depression.Outgoing, attractive child vs. introverted, lessattractive child.20The New Frontier: Molecular GeneticsGene-Environment InteractionGenes and environment affect our traits individually,but more important are their interactive effects.Alessia Pierdomenico/Reuters/CorbisRex FeaturesPeople respond differently toRowan Atkinson (Mr. Bean) than Orlando Bloom.21Molecular genetics is a branch extension of behaviorgenetics that asks the question, “Do specific genesinfluence behavior?”22Molecular Genetics: Promises and PerilsEvolutionary Psychology: UnderstandingHuman NatureMolecular geneticists are trying to identify genes thatput people at risk for disorders. With this kind ofknowledge, parents can Molecular genetics studies why we as organisms aredistinct.decide to abort pregnancies in which the fetus is suspectedof having such disorders.Take steps to address elevated risk for such disorders (e.g.,learning disabilities).However, this opens up a real concern regardingethical issues involving such choices.23Evolutionary psychology studies why we as humansare alike. In particular, it studies the evolution ofbehavior and mind using principles of naturalselection.244

Artificial SelectionNatural SelectionNatural selection is an evolutionary process throughwhich adaptive traits are passed on to ongoinggenerations because these traits help animals surviveand reproduce.Biologists like Belyaev and Trut (1999) were able toartificially rear and domesticate wild foxes, selectingthem for friendly traits. Dogs are another example ofartificial selection.Preference for fatty foods & sweetsSkin tone vis-à-vis climate25Any trait that is favored naturally or artificiallyspreads to future generations.26Human TraitsHuman SexualityA number of human traits have been identified as aresult of pressures afforded by natural selection.Gender Differences in SexualityMales and females, to a large extent, behave andthink similarly. Differences in sexes arise in regardsto reproductive behaviors.Why do infants fear strangers when they becomemobile?Why are most parents so passionately devoted to theirchildren?Why do people fear spiders and snakes and notelectricity and guns?Question (summarized)MaleFemaleCasual sex60%35%Sex for affection25%48%Think about sex everyday54%19%2728Mating PreferencesMating PreferencesNatural selection has caused males to send their genesinto the future by mating with multiple females sincemales have lower costs involved.Males look for youthful appearing females in order topass their genes into the future. Females, on the other,hand look for maturity, dominance, affluence andboldness in males.However, females select one mature and caring malebecause of the higher costs involved with pregnancyand nursing.29Data based on 37 cultures.305

Critiquing the Evolutionary PerspectiveEvolutionary Psychologists ReplyEvolutionary psychologists take a behavior and workbackward to explain it in terms of natural selection.Evolutionary psychologists argue that we need to testbehaviors that expound evolutionary principles.Evolutionary psychology proposes genetic determinismand undercuts morality in establishing society.Evolutionary psychologists remind us how we haveadapted, but do not dictate how we ought to be.Where gender roles are unequal, gender preferencesare wide, but when they are closely equal, preferencesnarrow down.Males and females are more alike than different, and ifwe study these differences we can establish theircauses.3132Parents and PeersPrenatal EnvironmentParents and Early ExperiencesWe have looked at how genes influence ourdevelopmental differences. What about theenvironment? How do our early experiences, ourfamily, our community and our culture affects thesedifferences?Identical twins who share the same placenta (b) aremore alike than those who do not (a), suggestingprenatal influences on psychological traits.We begin with the prenatal environment.3334Experience and Brain DevelopmentExperience and FacultiesEarly postnatal experiences affect braindevelopment. Rosenzweig et al. (1984) showed thatrats raised in enriched environments developedthicker cortices than those in impoverishedenvironment.Early experiences during development in humansshows remarkable improvements in music,languages and the arts.Courtesy of C. Brune35366

Parental InfluenceBrain Development and AdulthoodParental influence is largely genetic. This support isessential in nurturing children. However, othersocializing factors also play an important role.Brain development does not stop when we reachadulthood. Throughout our life, brain tissuecontinues to grow and change.Miquel L. FairbanksBoth hotos courtesy of Avi Kani and LeslieUngerleider, National Institue of Mental HealthA well-learned finger-tapping task leads tomore motor cortical neurons (right) than baseline.37Although raised in the same family,some children are greater risk takers.38Peer InfluenceCultural InfluencesChildren, like adults, attempt to fit into a group byconforming. Peers are influential in such areas aslearning to cooperate with others, gaining popularity,and developing interactions.Humans have the ability to evolve culture. Culture iscomposed of behaviors, ideas, attitudes, values andtraditions shared by a group.Kevin R. Morris/CorbisOle Graf/ zefa/ Corbis3940Variation Over TimeVariation Across CultureCultures differ. Each culture develops norms – rules foraccepted and expected behavior. Men holding hands inSaudi Arabia is the norm (closer personal space), butnot in American culture.Cultures change over time. The rate of this change may beextremely fast. In many Western countries, culture has rapidlychanged over the past 40 years or so.Jason Reed/ Reuters/CorbisCartoonsIdeal Body TypesThis change cannot be attributed to changes in the human genepool because genes evolve very slowly.41427

Culture and the SelfCulture and the SelfIf a culture nurtures anindividual’s personal identity,it is said to be individualist,but if a group identity isfavored then the culture isdescribed as collectivist.A collectivist support system canKyodo Newsbenefit groups who experiencedisasters such as the 2005earthquake in Pakistan.4344Gender DevelopmentGender Differences in AggressionBased on genetic makeup, males and females arealike, since the majority of our inherited genes (45chromosomes are unisex) are similar.Men express themselves and behave in moreaggressive ways than do women. This aggressiongender gap appears in many cultures and at variousages.Males and females differ biologically in body fat,muscle, height, onset of puberty, and life expectancy.In males, the nature of this aggression is physical.Cultural influences (e.g., Southern “culture of honor”)4546Gender Differences and ConnectednessGender RolesYoung and old, women form more connections(friendships) with people than do men. Menemphasize freedom and self-reliance.Our culture shapes our gender roles — expectationsof how men and women are supposed to behave.Dex Image/ Getty ImagesOliver Eltinger/ Zefa/ Corbis47Gender Identity — means how a person perceiveshimself or herself in terms of gender.Strong vs. weak gender identity488

Gender Roles: TheoriesReflections on Nature and Nurture1. Gender Schema Theory suggests that we learn acultural “recipe” of how to be a male or afemale, which influences our gender- basedperceptions and behaviors.2. Social Learning Theory proposes that we learngender behavior like any other behavior—reinforcement, punishment, and observation.49509

Nature, Nurture, and Human Diversity Gender Development The Nature of Gender The Nurture of Gender Reflections on Nature and Nurture. 2 7 Nature, Nurture, and Human Diversity Similarities Differences Genes: Same set of . Lecture_04_Nature, Nurture, Diversity.ppt Author: