Anjali Pillai PSYC 111 Chapter 4 Notes Nature Nurture and Human Diversity Behavior Genetics Predicting Individual Differences Genes Our Codes for Life Behavior genetics the study of the relative power and limits of genetic and environmental influences on behavior Environment every nongenetic influence from prenatal nutrition to the people and things around us Chromosomes threadlike structures made of DNA molecules that contain the genes DNA deoxyribonucleic acid a complex molecule containing the genetic information that makes up the chromosomes Genes the biochemical units of heredity that make up the chromosomes a segment of DNA capable of synthesizing a protein Genome the complete instructions for making an organism consisting of all the genetic material in that organism s chromosomes o 46 chromosomes 23 mother and 23 father composed of coiled DNA Genes small segments of DNA 20 25 000 Can be active or inactive env factors turn on genes and they make protein body building blocks Shared genome amongst humans 96 similar to chimps small diff big diff Person to person variations explains differences traits Complex traits intelligence group of genes Twin and Adoption Studies Identical twins twins who develop from a single monozygotic fertilized egg that splits in two creating two identical organisms Fraternal twins twins who develop from separate dizygotic fertilized eggs They are genetically no closer than brothers and sisters but they share a fetal environment o Identical v Fraternal Twins Identical twins are genetically identical but don t always have same number of copies of those genes or same placenta nutritional differences Fraternal twins not identical shared genes higher likelihood of shared exp s Identical twins behaviorally similar in terms of extraversion and neuroticism outgoingness and emotional instability o Separated Twins Jim Lewis and Jim Springer Identical in persona intelligence heart rate brain waves voice etc More studies physical attributes and personality similarities in sep twins o Biological v Adoptive Relatives genetic relatives and env relatives More similar to biological parents persona Parents still influence attitudes manners faith politics etc Adoptive parents less likely to abuse neglect screened so children thrive and more attached to parents and altruistic benefit from adoption Temperament and Heredity Temperament a person s characteristic emotional reactivity and intensity o Heredity predisposes this personality trait peek into future persona o Anxious infants high and variable heart rates The New Frontier Molecular Genetics Molecular genetics the subfield of biology that studies the molecular structure and function of genes o Seeks to ID specific genes influencing behavior and to find some of many genes that control body weight sexual orientation and extraversion o Diseases and risks can be pointed out Learning disabilities depression schizophrenia alcohol dependence o Potential predict risk so problems can be prevented before they happen Can tell parents risks for infants could lead to discrimination ethical probs o Should parents be able to produce embryo after screening pros and cons Heritability Heritability the proportion of variation among individuals that we can attribute to genes The heritability of a trait may vary depending on the range of populations and environments studied o Mathematically estimate this using twin and adoption studies o If heritability of intelligence is 50 means genetic influence explains half of observed variation among people If equal env heritability would be 100 vice versa o Heritable individual diff s don t imply heritable group diff s Gene Environment Interaction Interaction the interplay that occurs when the effect of one factor such as environment depends on another factor such as heredity Epigenetics the study of influences of gene expression that occur without a DNA change o Adaptive capacity shared biology enables developed diversity Genes and env genes react with env that trigger gene activity i e children experience same parents differently depending on own characteristics and qualities As we grow older select env s suited to our nature o Epigenetics env factors on gene expression Diet drugs stress can affect epigenetic molecules that reg gene expression Nature via nurture Evolutionary Psychology Understanding Human Nature Natural Selection and Adaptation Evolutionary psychology the study of the evolution of behavior and the mind using principles of natural selection Natural selection the principle that among the range of inherited trait variations those that lead to increased reproduction and survival will most likely be passed on to succeeding generations Mutation a random error in gene replication that leads to a change o Belyaev and Lyudmila fox domestication over time traits selected that reproductive advantage will prevail with dogs too o Explains natural human tendencies mutations give us adaptation to varied env s Adaptive flexibility fitness ability to survive and reproduce Evolutionary Success Helps Explain Similarities o Our Genetic Legacy Behavioral and biological similarities come from shared genome gen profile 5 gen diff s from population group diff 95 w in populations Early humans answered q related to survival choices made that contributed their genes to later generations some successful some not Success enhancing genes selected through mating as well humans td Universal moral grammar Marc Hauser shared moral instinct Some natural dispositions mismatched with today leftovers from past o Evolutionary Psychology Today Second Darwinian revolution application of evolutionary principles to psychology Why fear of spiders and heights and not guns and electricity An Evolutionary Explanation of Human Sexuality Gender in psychology the biologically and socially influenced characteristics by which people define male and female o Gender Differences in Sexuality Males more sexually inclined i e casual hookups Gay men more interest in hookups and attractiveness than lesbians 2 3 gay pop men but only 1 3 of them wanted legal partnership o Natural Selection and Mating Preferences women pair wisely men widely Men healthy youthful fertile women mid twenties Women mature dominant bold affluent long term How Does Experience Influence Development Experience and Brain Development o Experience enhances neural development handled infants develop faster neurologically and premies massage therapy helps to get
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