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1 Behavior Genetics: Predicting Individual Differences Genes: Our Codes for Life Twin and Adoption Studies Temperament and Heredity Nature and Nurture Gene-Environment Interaction 2 Evolutionary Psychology: Understanding Human Nature Natural Selection An Evolutionary Explanation of Human Sexuality 3 Behavior Geneticists study our differences and weigh the relative effects of heredity and environment. 4 Chromosomes containing DNA (deoxyribonucleic acid) are situated in the nucleus of a cell. 5 Segments within DNA consist of genes that make proteins to determine our development. Dominant vs. Recessive Genes: Examples 6 GENOTYPE . PHENOTYPE The observable physical or The genetic makeup, as biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences. distinguished from the physical appearance, of an organism or a group of organisms. How ugly you are supposed to be. How ugly you actually are You can change your phenotype-colored hair, contacts, etc.. https://youtu.be/prkHKjfU mMs 7 Studying the effects of heredity and environment on two sets of twins, identical and fraternal, has come in handy. 8 Critics of separated twin studies note that such similarities can be found between strangers. Researchers point out that differences between fraternal twins are greater than identical twins. Bob Sacha 9 Thomas Bouchard—good name to remember! Minnesota Twin Studies started in 1979 and continue to this day. They are given tests that measure their personalities, intelligence, heart rate, brain waves… 10 This study showed examples of similarities. Jerry and Mark Newman (separated at birth). Shared characteristics-firefighters, same mustache and sideburns, same glasses, One studied forestry in college-other wanted to but worked for city trimming trees instead. One installed fire alarms-other installed sprinklers. Both bachelors and attracted to same type of woman. Both only drink Budweiser The Jim Twins 11 A number of studies compared identical twins reared separately from birth, or close thereafter, and found numerous similarities. Separated Twins Personality, Intelligence Abilities, Attitudes Interests, Fears Brain Waves, Heart Rate 12 Studies show that Identicals have 85% similarity in IQ and Fraternals-60%. Behavior geneticists say ½ the variation for IQ is because of genetics. Critics: Same prenatal environment Spend avg. of 5 mths together b/f being separated Avg. of 2 years together before second study. 13 Adoption studies, as opposed to twin studies, suggest that adoptees (who may be biologically unrelated) tend to be different from their adoptive parents and siblings. 14 Adoptive studies strongly point to the simple fact that biologically related children turn out to be different in a family. So investigators ask: Do siblings have differing experiences? Do siblings, despite sharing half of their genes, have different combinations of the other half of their genes? Ultimate question: Does parenting have an effect? 15 Parenting does have an effect on biologically related and unrelated children. Parenting Influences Children’s Attitudes, Values Manners, Beliefs Faith, Politics 16 Some human traits are fixed, such as having two eyes. However, most psychological traits are liable to change with environmental experience. Genes provide choices for the organism to change its form or traits when environmental variables change. Therefore, genes are pliable or self-regulating. 18 The extent to which differences in the appearance of a trait across several people can be accounted for by differences in their genes. Correlational term—only positive value (0 to 1) Heritability IS NOT the same as inherited https://www.khanacademy.org/testprep/mcat/behavior/behavior-andgenetics/v/heritability 19 The subfield of biology that studies the molecular structure and function of genes. Seek to identify specific genes that influence behavior. Goal is to find those genes that together orchestrate traits such as body weight, sexual orientation, and extraversion. **Is it a good idea?Do the benefits (finding cures) outweigh the potential misuse (selective breeding)? 22 Evolutionary psychology studies why we as humans are alike. In particular, it studies the evolution of behavior and mind using principles of natural selection. This approach is helpful in raising the “why of behavior” question that is so central to the discipline of psychology. 23 Natural selection is an evolutionary process through which adaptive traits are passed on to ongoing generations because these traits help animals survive and reproduce. 24 http://www.ted.com/talks/jim_fallon_explori ng_the_mind_of_a_killer.html 25 Biologists like Belyaev and Trut (1999) were able to artificially rear and domesticate wild foxes, selecting them for friendly traits. L.N. Trur, American Scientist (1999) 87: 160-169 Any trait that is favored naturally or artificially spreads to future generations. 26 A number of human traits have been identified as a result of pressures afforded by natural selection. Why do infants fear strangers when they become mobile? Why do people fear spiders and snakes and not electricity and guns? How are men and women alike? How and why do men’s and women’s sexuality differ? 27 Gender Differences in Sexuality Males and females, to a large extent, behave and think similarly. Differences in sexes arise in regards to reproductive behaviors. Question (summarized) Male Female Casual sex 58% 34% Sex for affection 25% 48% Think about sex everyday 54% 19% 28 Natural selection has caused males to send their genes into the future by mating with multiple females since males have lower costs involved. THERE IS A GENETIC ARGUMENT AS TO WHY MEN ARE “PLAYERS”—just trying to spread their genetic code. However, females select one mature and caring male because of the higher costs involved with pregnancy and nursing. 29 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. 30 In certain animal species, a male that has become sexually exhausted from repeated copulation with the same female will demonstrate renewed vigor if presented with a succession of new females. This phenomenon is called the Coolidge Effect b/c of exchange b/w Pres. And Mrs. Calvin Coolidge. 31 While touring a farm, Mrs. Coolidge was impressed by the untiring sexual activity of one rooster. “You might point that out to Mr. Coolidge” she said. Hearing her remark, Pres. Coolidge asked the farmer whether a different hen was used each time. When informed that this was the case-he said “You might point that out to Mrs. Coolidge.” 32 Evolutionary psychologists take a behavior and work backward to explain it in terms of natural selection. Evolutionary psychology proposes genetic determinism and undercuts morality in establishing society. Where genders are unequal, gender preferences are wide, but when they are closely equal, preferences narrow down. 33 Evolutionary psychologists argue that we need to test behaviors that expound evolutionary principles. Evolutionary psychologists remind us how we have adapted, but do not dictate how we ought to be. Males and females are more alike than different, and if we study these differences we can establish their causes. 34