Genetics, Behaviour & Evolutionary Psychology

1. Genetics, Behaviour& Evolutionary Psychology With reference to relevant research studies, to what extent does genetic inheritance influence behaviour?

2. Behavior Genetics: Predicting Individual Differences Behavior Geneticists study our differences and weigh the relative effects of heredity and environment.

3. Genes: Our Codes for Life Chromosomes containing DNA (deoxyribonucleic acid) are situated in the nucleus of a cell.

4. Genes: Our Codes for Life Segments within DNA consist of genes that make proteins to determine our development.

5. Genome Genome is the set of complete instructions for making an organism, containing all the genes in that organism. Thus, the human genome makes us human, and the genome for drosophila makes it a common house fly.

6. The Genetic Revolution If it were possible, would you want to take a genetic test telling you which diseases you are likely to suffer from later in life? If you or your spouse were pregnant, would you want the unborn child tested for genetic defects? Do you think it should be legal for employers to use genetic tests in deciding whom to hire?

7. Twin Biology Studying the effects of heredity and environment on two sets of twins, identical and fraternal, has come in handy.

8. Twins and Procedures Behavior geneticists’ effects of shared and unique environments on total or partial genetic makeup.

9. Separated Twins A number of studies compared identical twins raised separately from birth, or close thereafter, and found numerous similarities.

10. Separated Twins 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

11. Adoption Studies 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.

12. Adoptive Studies 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?

13. Parenting Parenting does have an effect on biologically related and unrelated children.

14. Temperament Studies Temperament refers to a person’s stable emotional reactivity and intensity. Identical twins express similar temperaments, suggesting heredity predisposes temperament. BUT – Does the environment play a role as well?

15. Bringing Up Monkey (clip) • Scientific American Frontiers 2nd ed (Clip #23/9:40) • What two personality styles have been identified in Rhesus monkeys? • How do these styles relate to a monkey’s relationship/attachment style with the mother? • How did Steve Sumi and his team investigate the origins of these personality styles? • What were their major findings? • Provide evidence that: a) the environment has an impact on temperament; b) biological programming has an impact on temperament • What value do animal studies have on contributing to our understanding of human development?

16. Temperament Activity (homework) • Go to www.preventiveoz.org and summarize the findings under these headings: • Importance of temperament • Origins/history of temperament • Major temperament areas • Appearance of temperament • Gender differences • Impact of birth order

17. Heritability Heritability refers to the extent to which the differences among people are attributable to genes.

18. Group Differences If genetic influences help explain individual diversity in traits, can the same be said about group differences? Not necessarily. Individual differences in weight and height are heritable and yet nutritional influences have made westerners heavier and taller than their ancestors were a century ago.

19. Nature and Nurture 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.

20. Gene-Environment Interaction Genes can influence traits which affect responses, and environment can affect gene activity. A genetic predisposition that makes a child restless and hyperactive evokes an angry response from his parents. A stressful environment can trigger genes to manufacture neurotransmitters leading to depression.

21. Gene-Environment Interaction Genes and environment affect our traits individually, but more important are their interactive effects. Alessia Pierdomenico/Reuters/Corbis Rex Features People respond differently to Rowan Atkinson (Mr. Bean) than Orlando bloom.

22. Alcohol Addiction – Hereditary Factors • The Mind, clip #29/ 11:40 • Describe the brain deficits from which alcoholics suffer. • What evidence has been offered for a genetic/hereditary factor in alcoholism? • How does the environment interact with these hereditary factors to produce alcohol addiction?

23. The New Frontier: Molecular Genetics Molecular genetics is a branch extension of behavior genetics that asks the question, “Do genes influence behavior?”

24. Molecular Genetics:Promises and Perils Molecular geneticists are trying to identify genes that put people at risk for disorders. With this kind of knowledge, parents can decide to abort pregnancies in which the fetus is suspected of having such disorders. However, this opens up a real concern regarding ethical issues involving such choices.

25. Twin Studies MZ (identical twins) share 100% genes vs. DZ (fraternal) share approx 50% genes Siblings share 50% genes Concordance rate calculated – likelihood that if one individual has a trait, the other will also have it (helps determine degree to which a trait is inherited)

26. Twin Studies con’t One twin acts as control for another Bouchard’s study only calculated concordance rates and did not look at environmental factors (equal environment assumption) MZ twins are compared to DZ twins – if high rates in MZ vs. DZ, then trait is assumed to be linked to genetics

27. Key Study – Bouchard et al (1990) Longitudinal study; self-selected sample of MZT and MZA to look at concordance rates IQ (measured by WAIS) had a concordance rate of 69% for MZA and 88% for MZT Environmental factors play a role but intelligence is largely inherited (approx 70% of variation attributed to genetics)

28. Bouchard con’t • Sample was primarily white, middle class in industrialized nation) • IQ can be increased (envir’l influence) • BUT • Correlational data does not create cause-effect • Rates were far below 100% so relative influence of genes is difficult to calculate • No control for environmetal variables • Difficult to generalize (self-selected sample)

29. Additional intelligence studies • Course Companion (pgs. 55-56) • Outline the following: • Criticisms of Bouchard’s study • Scarr & Weingberg (1977) and Horn et al (1979) on IQ scores • Wahlsten (1977) contributions • Hainer et al & less effort hypothesis • Plomin & Petrill (1997) • The Flynn effect

30. Natural Selection Natural selection is an evolutionary process through which adaptive traits are passed on to ongoing generations because these traits help animals survive and reproduce.

31. Artificial Selection 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.

32. Human Traits 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 are most parents so passionately devoted to their children? Why do people fear spiders and snakes and not electricity and guns?

33. Human Sexuality Gender Differences in Sexuality Males and females, to a large extent, behave and think similarly. Differences in sexes arise in regards to reproductive behaviors.

34. Mating Preferences Natural selection has caused males to send their genes into the future by mating with multiple females since males have lower costs involved. However, females select one mature and caring male because of the higher costs involved with pregnancy and nursing.