 Behavior typical of every culture  Communicate both verbally and nonverbally, enforce rules of etiquette, and show favoritism toward groups member, including preference for kin over non-kin.  They avoid incest, fear snakes, and exchange gifts.  Demonstrate modesty in sexual behavior and bodily functions (even when clothes are non worn).  Labor is divided by age and by gender  People form beliefs about death and disease  Men are more aggressive and women provide child care.  ALL cultures have taboos, sanctions against society, and mechanisms to deal with theft, murder, and rape. 1

 People everywhere recognize marriage  People mimic, flirt, envy, empathize, joke, tease, and dance and make music. 2

 What is the difference between behavior genetics and evolutionary psychology?  What do we mean by nature and nurture?  watch?v=8mvZ4EbPbME watch?v=8mvZ4EbPbME 3

4 Behavior Genetics: the study of the relative effects of genes and environment on behavior. Behavior Geneticists study our differences and weigh the relative effects of heredity and environment.

 Genes – biochemical units of heredity that make up a chromosome  Chromosome – Threadlike structures made of DNA molecules that contain genes (46 total, 23 from each parent)  DNA (deoxyribonucleic acid) – complex molecule that contains genetic information that makes up chromosomes  Cell -> Nucleus -> Chromosomes -> DNA -> Genes 5

6 Chromosomes containing DNA (deoxyribonucleic acid) are situated in the nucleus of cells. In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females. Females have two copies of the X chromosome, while males have one X and one Y chromosome.

7 Segments within DNA consist of genes that make proteins to determine our development

 Genes made up of nucleotides (A,T,C, or G)  Genome – complete instructions for making an organism consisting of all genetic material in its chromosomes  Humans have about 30,000 different genes  Does anyone know the animal humans are most genetically related to? 8

 All organisms have many genes corresponding to various biological traits, some of which are immediately visible, such as eye color or number of limbs, and some of which are not, such as blood type, increased risk for specific diseases, or the thousands of basic biochemical processes that comprise life. 9

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11 Genome the set of complete instructions for making an organism. It contains all genes in that organism. The human genome makes us human, and the genome for drosophila makes it a common house fly.

 Genes are responsible for predisposing our appearance and behavior, not concretely determining either.  Predisposition – a situation that allows something else to occur but doesn’t necessarily cause it to occur; “Her genetic makeup left her with a predisposition to develop Alzheimer's.”  Mutations – random error in gene replication that lead to a change in genetic code 12

 Natural selection – the idea that, among the inherited trait variations, those contributing to survival will most likely be passed on to future generations.  Adaptation – species changing genetically to better survive in their environment. 13

 Identical twins – twins that develop from a single fertilized egg and then split in half; are genetically identical.  Fraternal twins – twins that develop from separate eggs; no more related genetically than normal siblings.  Twin studies have discovered that identical twins are strikingly similar is intelligence, attitude and even brain waves! 14

 Minnesota Twin Studies - Monozygotic (mz) and dizygotic (dz) twins separated at birth  Adoption studies Comparisons of adopted children and their biological and adoptive parents  Temperament studies findings. Role of heredity, predispositions and stability  The New Frontier: Molecular Genetics – Specific genes for specific behaviors and disorders  Epigenetics changes in gene expression caused by environmental factors, not by changes in the underlying DNA 15

16 Studying the effects of heredity and environment on two sets of twins, identical and fraternal, has been valuable

Identical Twins Reared Together v. Identical Twins Reared Apart Same genes,Same genes Same environment Different environment 17 Greater difference between these two groups indicates greater role of the environment (“nurture”)

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 Herit – comes from the word inherit.  To inherit means to process something that someone else has given you  We inherit traits and qualities from our parents.  - ability – means “capable.”  If a trait is genetically passed from one generation to the next, then it is capable of showing up in the offspring of parents who possess the genes for that trait. 19

 The percentage of trait variation within a group that can be attributed to genetic differences (v. environmental).  For example, assume you all were raised in identical, enriched environments – all differences in I.Q. are then due to genetic difference (100% heritability)  Determined by comparing MZ twins separated at birth. Remember, heritability estimates are NOT measures of the importance of genes in the production of a trait (e.g., I inherit 65% of my intelligence from…) 20

21 Sara is very outgoing and agreeable Suzy is timid and non- conforming If this pair of IDENTICAL twins is the population, the percent of the personality differences attributable to genetic differences between them is?? The heritability is 0%.

22 Joe and Hank are not related. At birth, both were placed in identical environments that remained identical until they were 10 years old At 10, Joe is outgoing and friendly At 10, Hank is with- drawn and shy In this (very small) population, what is the heritability of their personality traits? In other words, what percentage of the difference is attributable to genes? Heritability is 100%

23 If genetic influences help explain individual diversity in traits, can the same be said about group differences? No. Individual differences in weight and height are heritable, but nutritional influences have made westerners heavier and taller than their ancestors were a century ago, or others in the developing world.

 Average risk of schizophrenia among biological relatives of people with schizophrenia. 24

Criticisms: 1) Adoption agencies try to place twins in similar families so the variation in environment may be small. 2) There is a very limited sample

 Studies of adopted children show that they exhibit similar personality traits of their biological parents.  However, adopted children tend to be smarter, more productive and more successful than their biological parents.  Nurture is back in the game! 26

 Note: Two related siblings that grow up in the same family are strikingly different in personality (as I’m sure many of you can attest to).

Separated Twins Personality, Intelligence Abilities, Attitudes Interests, Fears Brain Waves, Heart Rate 28 A number of studies compared identical twins raised separately from birth, or close thereafter, and found numerous similarities.

29 Is child more like adoptive parents… …or biological parents? Adoptive Parents - NurtureBiological Parents - Nature

 Temperament refers to a person’s stable emotional reactivity and intensity. Identical twins research and that of Jerome Kagan (reactivity studies) suggest that temperament is fixed or stable, and under some genetic influence. Environmentalists vehemently disagree  Kagan The Temperamentalist  deas/articles/2004/08/29/the_temper amentalist?pg=full 30

 Are parents to blame for success/failure of children? Studies say “not really”.  Siblings raised together tend to be as different personality-wise as two random people on the street. 31

 What do we mean by environment?  Prenatal experiences, early childhood experience, parental and peer influence, culture  Early experience – Rosenzweig’s and Greenough’s enriched environment studies, developmental plasticity, synaptic pruning, Bronfenbrenner’s proximal processes theory, and epigenetics research  Does peer influence exceed parental? Judith Harris  Cultural influences, e.g., collective v. individualistic societies, cross-cultural research notes similarities and variations across culture and some of their sources 32

 Prenatal experiences, early childhood experience, parental and peer influence, culture.  Early experience – Rosenzweig’s and Greenough’s enriched environment studies, developmental plasticity, synaptic pruning, Bronfenbrenner’s proximal processes theory, and epigenetics research 33

 Does peer influence exceed parental? Judith Harris  She challenges the idea that the personality of adults is determined chiefly by the way they were raised by their parents.  She looks at studies which claim to show the influence of the parental environment and claims that most fail to control for genetic influences. ▪ For example, if aggressive parents are more likely to have aggressive children, this is not necessarily evidence of parental example; it may also be that aggressiveness has been passed down through the genes. ▪ Harris argues that children identify with their classmates and playmates rather than their parents, modify their behavior to fit with the peer group, and this ultimately helps to form the character of the individual. 34

 Cultural influences, e.g., collective v. individualistic societies, cross-cultural research notes similarities and variations across culture and some of their sources  The individualistic countries tend to put rights and privacy first. People in these societies tend to overvalue their own skills and overestimate their own importance to any group effort. People in collective societies tend to value harmony and duty. They tend to underestimate their own skills and are more self-effacing when describing their contributions to group efforts.  Collectivist societies tend to pop up in parts of the world, especially around the equator, with plenty of disease-causing microbes. In such an environment, you'd want to shun outsiders, who might bring strange diseases, and enforce a certain conformity over eating rituals and social behavior. 35

36 Identical twins who share the same placenta are more alike than those who do not, suggesting prenatal influences on psychological traits

 For our brains to reach their developmental potential, early experience is CRITICAL.  Children raised in abusive homes tend to be less intelligent that children raised in loving environments.  Score one for nurture! 37

38 Early postnatal experiences affect brain development. Rosenzweig et al., showed that rats raised in enriched environments developed thicker cortices than those in impoverished environments. Subsequent work by Greenough

39 While some traits are fixed (ear lobes, tongue curl, PTC) most behavioral traits are modified by or under the influence of environmental experience. Our previous understanding of Nature versus Nurture turned out to be a false dichotomy Genes can influence traits which affect responses. And so, environment can affect gene activity. In such circumstances genes are allowed to be expressed (e.g., a genetic predisposition to restlessness evokes an angry response from a parent which, in turn, results in fuller expression of the genetic tendency Related notion of maximal expression

40 Epigenetics and Gene Expression Epigenetics refers to changes in gene expression caused by environmental factors, not by changes in the underlying DNA sequence. Changes may remain for the remainder of the cell's life and may last for multiple generations. However, there is no change in the underlying DNA sequence of the organism, instead, environmental factors cause the organism's genes to behave (or "express themselves") differently

 Discover Article 1. Describe Jirtle and Waterland’s experiment and its significance 2. Explain how epigenetics is related to, but different than, genetics 3. How does epigenetics change the “genes as fate” mentality? 4. Describe Meaney’s research and the challenges it offers to the traditional nature-nurture debate regarding behaviors. What are the social and political implications of this research? 5. Briefly describe Pembrey and Bygren’s work in the area of human epigenetics 41

42 Molecular geneticists are currently seeking to identify genes that put people at risk for specific disorders This raises ethical issues involving choices to abort or even alter genes related to genetic predispositions - Mental illness, Addiction? Criminality? Homosexuality? WZU

Parenting Influences children’s Attitudes, Values Manners, Beliefs Faith, Politics 43 While biological inputs are significant, parenting does have a considerable effect on both biologically related and unrelated children

 Peers hold a heavy influence on the behaviors of individuals (i.e. smoking, drinking, promiscuity )  Bandwagon phenomenon  “Fitting In”  Parents influence behaviors of children by supplying them the environment from which they have to work within (i.e. parents “choose” which neighborhood to live in) 44

Peers are influential in such areas as learning to cooperate with others, gaining popularity, and developing interactions Judith Rich Harris’ Do Parents Matter?Do Parents Matter? 45 The Role of Peer Influence

46 Cultures differ. Each culture develops norms – rules for accepted and expected behavior. Men holding hands in Saudi Arabia is the norm. Norms are behavioral expectations; what is allowed to be by the group

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48 Evolutionary psychology studies why we as humans are alike. In particular, it studies the evolution of behavior and mind using principles of natural selection

 Ethology (Lorenz) – science of animal behavior. Fixed action patterns- A fixed action pattern (FAP) is an instinctive behavioral response triggered by a very specific stimulus. Once triggered, the FAP behavior can’t be stopped ‘midstream’, but must play out to completion. Yawning is one example.  Sociobiology – Species-wide social behavior i.e, aggression and reciprocal altruism, kin selection  Are humans subject to behavioral similarities and tendencies that allow us to pass on our genes? Are behaviors based in natural selection, i.e., reproductive success  Evolved psychological mechanisms (EPM) e.g., sexual behavior, mating preferences, parental investment, kin selection, incest taboos, fear of strangers, heights, snakes. Do you think these are inborn? 49

Question (summarized)MaleFemale Casual sex60%35% Sex for affection25%48% Think about sex everyday54%19% 50 Gender Differences in Sexuality

51 Males look for youthful appearing females in order to pass their genes into the future. Females, on the other, hand look for maturity, dominance, affluence and boldness in males. Data based on 37 cultures.

 Critiquing the Evolutionary Perspective  The central premise is impossible to prove. Predictive power is null.  It’s hindsight bias, reductionist and dangerous. Potential justification for harmful behaviors and attitudes  EPs respond  EP does not imply genetic determinism, in fact adaptation is premised in environmental influence  EP instructs us to change our destructive evolutionary behaviors 52