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Unit 4: Mods 6-11 & Barron’s 9: Nature, nurture, and human development Mod 6 essentials: Behavior genetics and evolutionary psychology 1. 2. 3. 4. 5. 6. 7. 8. 9. What distinguishes behavior geneticists from other kinds of psychologists? Define DNA, chromosomes, gene, and genome. What conclusions have behavior geneticists drawn by studying identical twins, fraternal twins, and adopted children? How have studies on temperament contributed to our understanding of nature and nurture? What is heritability? What are molecular genetics and epigenetics and how are they contributing to psychology in the 21st c.? What is the main focus of evolutionary psychologists? What explanations do evo. psychs. give for human sexuality behaviors? What are the criticisms of the evolutionary perspective? 1. What distinguishes behavior geneticists from other kinds of psychologists? •They look at both nature and nurture causes of behaviors!! •They are mostly interested in answering: What causes us to be unique, different than one another? • Behavior geneticists are interested in how genes AND environments, from womb to tomb, influence our behaviors AND create individual differences – Womb • effects of prenatal nutrition on brain and body development • exposure to teratogens (environmental toxins that reach developing fetus) that create deformities, mutations • exposure to virus, parasites if mom gets them while preg. – Lifetime outside the womb • relationships, interactions with people • interactions with the world and experiences • trauma, accidents, diseases 2. The language of geneticists • • • • • • DNA : the chemical components of chromosomes Chromosomes: Human has 23 pair—they consist of genes we inherit from our mom and our dad Genes: DNA sequences on chromosomes that help determine human characteristics and govern physiological processes— humans have approx. 30,000 genes Allele: ½ of a gene pair—1 exists on each paired chromosome Human genome is the map of 30,000 possible genes existing in human kind Human karyotype (# and appearance of chromosomes in a species) Word choices alleles chromosomes DNA genes genome karyotype • Genotype: The genetic constitution of an individual. – Unless you have an identical twin, you have a unique genotype made up of half of dad’s and half of mom’s chromosome • Phenotype: The set of observable characteristics of an individual resulting from the expression of genes and/or interaction of its Punnett square: Diagram genotype with the environment used to predict gene – height –influenced by diet expression based on – eye color influenced by dominant/recessive genes dominant allele – fingerprint influenced by In order to express itself, a recessive gene environmental factors in (lower case a) must be paired with another womb of developing fetus recessive gene! In above Punnett square, what is likelihood of baby having the “a” recessive disorder? 25%! Genetic variation from the norm: Mutations on genes, too many chromosomes, or not enough chromosomes! • • – Down’s syndrome—trisomy 21 (baby has 3 copies of 21st chromosome (1 in 800 live births) – Klinefelter (XXY) & Turner Syndrome (X) Recessive disorders (means you need 2 copies of the gene, 1 from mom, 1 from dad, to get disease. Neither mom nor dad needs to have disease—could just be a carrier of dormant gene!) – cystic fibrosis--hick, sticky mucus to build up in the lungs, digestive tract, and other areas of the body – PKU-- body cannot process the amino acid phenylalanine which is found in many foods—if eaten, can cause retardation – albinism--defect of melanin production that results in little or no color (pigment) in the skin, hair, and eyes. – Tay-Sachs disease--fatal Dominant disorders (means you only need1 copy of the gene from either dad or mom to get disease and disease is observable in mom or dad) – Huntington chorea—defect on gene; 4 neurodegenerative disorder – achondroplastic dwarfism—bone growth disorder due to mutation on gene – polydactyly—extra fingers or toes! What is heritability? heritability: the extent to which observed differences between 2 individuals can be attributed to their genetic differences Heritability range = 0.0 to 1.0 The lower the number, the more we can attribute difference between individuals to differences in their nurture (environments, experiences) The higher the number, the more we can attribute the difference between individuals to differences in their differences in genes BIG IMPORTANT IDEAS: 1.Heritability CANNOT be used to tell what % of any one individual’s traits or behaviors are caused by nature or nurture!! They are used to express what % of variation we see between people is due to genetics Example If happiness is 50% heritable, it does not mean that Joe’s happiness level is 50% determined by his genes and 50% determined by environment. It DOES mean that genetics influence 50% of the differences in happiness we see between him and another person. 2.If identical twins show difference in IQ, then we would say the heritability of IQ is 0 This is because the difference in their IQ MUST be attributable to environment since they have identical genes! Classic longitudinal experiment on self-discipline: The marshmallow test •Dr. Walter Mischel of Stanford University •Tempt 3-4 year-olds with a marshmallow •Tell them that they may eat it now OR wait 15-20 minutes while marshmallow is in front of them and receive a second if they do not eat it Video Why does self-discipline matter? Direct correlation between being able to delay gratification and future academic success, popularity, success in getting over frustrations and challenges, saying “no” to temptations 6. What are molecular genetics and epigenetics and how are they used in the field of psychology? • Molecular geneticists study the ways specific genes/groups of genes shape behavior – e.g. Look for a genes that might cause homosexuality or schizophrenia or ADHD or obesity or bipolar • Epigeneticists study the way our genes become “modified” by our interaction with our environments – The genes chemical structures do not actually become modified, BUT the expression of the genes does due to physiological changes at the DNA level that allow genes to “turn on” or “turn off” – In sum, your epigenome is chemical tags on your DNA that are created as you interact with the environment. These tags switch on or off your genes and can shape your behaviors! Epigenetics: The latest and greatest in science to explain how nurture acts on what nature endows! Epigenetics videos • Video link 1 (5 min) How environment in womb can make identical twins different • Video link 2 (5 min) Rat experiments—lick a rat pup!! 7. What is the main focus of evolutionary psychologists? • What makes us alike as humans and how do our genes drive our behaviors? – In contrast with molecular geneticists, evolutionary look at how genes explain male or female behavior or adult or child behavior rather than the behavior of the individual • Everything is about natural selection and survival of the fittest!! 8. What explanations do evo. psychs. give for human sexuality behaviors? • Who wants sex more often? Survey says... – MEN MEN MEN! • Who thinks about sex more often? survey says... – MEN MEN MEN! • Who associates sex with affection and cuddling? Survey says... – WOMEN, WOMEN, WOMEN! • Who has no problem with casual sex? survey says... – men men men • Who falls in love after an orgasm? – WOMEN, WOMEN, WOMEN! • Who is sexually charged by visual stimuli? – men men men! WHY? More on sexuality... What do women find attractive in mates (men)? • Taller than themselves • muscular • wider face • risk takers • dominant • affluent • protectors • good saliva * What do men find attractive in women? •youthful looking •smooth skin •big breasts •wide hips •a woman in heat* WHY??