Behavior Genetics and Evolutionary Psychology Module 6

1. Behavior Genetics and Evolutionary PsychologyModule 6

2. Behavior Genetics and Evolutionary Psychology Behavior genetics: Predicting Individual Differences • Genes: our Codes for Life • Twin Studies • Temperament Studies • Heritability • Gene-Environment Interaction • The New Frontier: Molecular Genetics

3. Behavior Genetics and Evolutionary Psychology Evolutionary Psychology: Understanding Human Nature • Natural Selection • An Evolutionary Explanation of Human Sexuality • Critiquing the Evolutionary Perspective

4. Nature, Nurture and Human Diversity

5. EvolutionNatural Selection • The evolutionary process by which some genes in a population spread more than others do, causing species to change over time. • Principles of Natural Selection: • Within a species, no two are alike. • Individuals differ in their suitability to their environment. • Those better suited are more likely to survive and reproduce. • Reproduction perpetuates the genes of better suited individuals.

6. EvolutionNatural Selection • Adaptations • Advantageous physical and psychological traits that are inherited • Mutations • Random gene copying errors that can spark evolution by natural selection

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

8. GenesWhat Genes Are and How They WorkGenetic Building Blocks

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

10. GenesHow Genes Affect Behavior Genotype The underlying DNA sequence that an individual inherits Phenotype An organism’s observable properties, physical and behavioral Genes contribute more directly to physical traits than to psychological characteristics.

11. The Nature-Nurture DebatesThe Pursuit of Heritability • Nature-Nurture Debate • The debate over the extent to which human behavior is determined by genetics and the environment. • Heritability • A statistical estimate of the percentage of the variability of a trait within a group that is attributable to genetic factors.

12. Twin Biology To study the effects of heredity and environment two sets of twins, identical and fraternal, have come in handy.

13. Twin and Procedures Behavior geneticists study the effects of shared and unique environments on total or partial genetic makeup.

14. Separated Twins A number of studies have looked at identical twins raised separately from birth or close there after and have found a number of similarities.

15. Adoption Studies Opposed to twin studies, adoption studies suggest that adoptees (who may be biologically unrelated) tend to be different from their adoptive parents and siblings.

16. 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 genes? Ultimate question: Does parenting have an effect?

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

18. Temperament Studies Temperament refers to a person’s stable emotional reactivity and intensity. Identical twins express similar temperaments, suggesting heredity predisposes temperament.

19. The Nature-Nurture DebatesGenetic Influences • Other studies of twins and adoptees show: • Genetic factors account for some differences in intelligence, verbal and spatial abilities, criminality, vocational interests, and aggressiveness. • There is a genetic component to psychological disorders, such as alcoholism, depression, and schizophrenia. • And, there is evidence for a genetic link to people’s attitudes toward issues and activities.

20. The Nature-Nurture DebatesGenetic InfluencesHeritability of Various Human Attributes • The role of genetic factors is shown by the extent to which identical twins are more similar to each other than are fraternal twin pairs.

21. The Nature-Nurture DebatesGenetic InfluencesHeritability of Attitudes • This study involved 672 twins who rated their attitudes on various issues and activities. • The results show some influence of genetic factors.

22. 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 angry responses from his parents. A stressful environment can trigger genes to manufacture neurotransmitters leading to depression.

23. 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 where fetuses are suspected of having such disorders But this opens up a real concern about ethical issues involving such choices.

24. Evolutionary Psychology: Understanding Human Nature Molecular genetics studies why we as organisms are distinct. Evolutionary psychology studies why we as humans are alike. In particular it studies the evolution of behavior and mind using principles of natural selection.

25. 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.

26. 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?

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

28. Mating Preferences Natural selection has pressurized males to send their genes into the future by mating with multiple females because of lower cost involved. But females because of higher costs involved with pregnancy and nursing select one mature and caring male.

29. Mating Preferences In order for males to pass their genes into future they look for youthful appearance in females. Females on the other hand look for maturity, dominance, affluence and boldness in males. Data based on 37 cultures.

30. Critiquing the Evolutionary Perspective 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 closely equal, preferences narrow down.

31. Evolutionary Psychologists Reply Evolutionary psychologists argue that we need to test behaviors that expound evolutionary principles. Evolutionary psychologists remind us how we have adapted, but does not dictate how we ought to be. Males and females are more alike than different, if we study these differences we can establish their causes.