Behavior Genetics and Evolutionary Psychology

1. Behavior Genetics and Evolutionary Psychology Module #8 PSY101

2. Genes: Our Biological Blueprint Chromosomes • threadlike structures made of DNA molecules that contain the genes DNA (deoxyribonucleic acid) • a complex molecule containing the genetic information that makes up the chromosomes • has two strands-forming a “double helix”- held together by bonds between pairs of nucleotides

3. Nucleus Chromosome Gene Cell DNA Genetics and Behavior 23 chromosomes – a gift from mom’s egg 23 chromosomes – a gift from dad’s sperm

4. Chromosome Problems • Female xx sex chromosomes • Male xy sex chromosomes At least one x chromosome is essential for life. A single y is never enough for development.

5. Chromosome Problems Some abnormal sex chromosome patterns: Turner’s syndrome xo http://en.wikipedia.org/wiki/Turner_syndrome Kleinfelter’s syndrome xxy http://genetics.emedtv.com/klinefelter-syndrome/klinefelter-syndrome-symptoms.htm l Double Y syndrome xyy http://en.wikipedia.org/wiki/XYY_syndrome Fragile-X syndrome xy (x is thin,fragile) http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002633/

6. Genes: Our Biological Blueprint • Genes • the biochemical units of heredity that make up the chromosomes • a segment of DNA capable of synthesizing a protein • Genome • the complete instructions for making an organism • consisting of all the genetic material in its chromosomes

7. Human Genome Project,Findings • Humans are 99.95% identical • Many human genes appear only in humans and appear to have come from bacteria. • One gene makes 2 or 3 proteins, complex chains of amino acids that carry out the tasks of life. • Every human’s genome shows the residues of evolution.

8. Dominant and Recessive Genes http://www.blinn.edu/socialscience/ldthomas/feldman/handouts/0203hand.htm • A dominant trait does not mean "more potent" and recessive does not mean "weaker." • The terms refer to the visible trait.

9. Genes: Our Biological Blueprint • Is there a difference between female and male brains? • What do you think? • What do we know?

10. Evolutionary Psychology • Evolutionary Psychology • study of the evolution of behavior using the principle of natural selection, which presumably favors genes that predispose behavior tendencies and information--processing systems that solved adaptive problems faced by our ancestors • Note: See handout 8-3

11. How Evolutionary Psychology Works • Many years of drought • Finches evolved thicker beaks • Enabled them to crack harder seeds • Over many years of heavy rains • Finches developed thinner beaks • Enabled them to eat softer seeds

12. E.P. , Children and Bedtime • Why do young children resist going to bed? • We say they are “spoiled.” Is it true? • In hunter-gatherer days, being alone in the dark was dangerous, monsters were real. • Present day hunter-gathers consider allowing a child to sleep alone to be child abuse.

13. Timothy Miller –Practical Implications of E.P. • Humans strive for the prerequisites of reproductive success • Wealth • Status • Love From an evolutionary perspective there is no such thing as enough reproductive success.

14. Genetic Effects on Taste The ability to taste Phenylthiocarbamide (PTC) • Is an inherited trait. • About 2/3 of Americans are tasters. • Determined by one pair of alleles, T and t • Ability to taste is dominant.

15. Genetics and EvolutionQuestions • Would you want to take a test telling you what diseases you may develop? • Would you want your unborn child tested for genetic defects? • Should employers use genetic tests when hiring?

16. Evolutionary Psychology • Gender (in psychology) • the characteristics, whether biologically or socially influenced, by which people define male and female • What do we look for in mates? Note: handout 8-4

17. Evolutionary Psychology Countries with dots were surveyed as to their mating preferences, in all 10,047 people in 37 countries were asked. Men – preferred attractive features, youth, and health Women – preferred wealth, maturity, social status, health, attractive

18. Evolutionary Psychology • Natural Selection • the principle that, among the range of inherited trait variations, those contributing to reproduction and survival will most likely be passed on to succeeding generations • Mutation • a random error in gene replication that leads to a change in the sequence of nucleotides • the source of all genetic diversity

19. Take the Sexual Attitudes Scale, 8-5. • What are your attitudes about sex?

20. Evolutionary Psychology Four dimensions of sexuality on the Hendrick Sexual Attitude Scale 1.permissiveness(items 1-21) = open, casual sexuality • sexual practices(items 22-28) = responsible, tolerant sexuality • communion in the relationship(items 29-37) = emotional, idealistic sexuality 4. instrumentality(items 38-42) = sex as egocentric and very biological

21. Evolutionary Psychology The Hendrick Sexual Attitude Scale (Handout 8-5) Some findings about sex: • Men identify a more casual, less conventional, and more manipulative approach. • Women are into love/sexuality – practical and conventional approach. • Very religious people differed from most other’s responses. • Those who had been in love several times were more endorsing of “permissiveness” and some instrumentality. • Those currently in love were less permissive and instrumental and more endorsing of communion.

22. Just for Fun • http://www.youtube.com/watch?v=Vqiw-Kqtlr0

23. Critiques of Evolutionary Psychology • If men are committed to their mates, only those genes survived. • If men are only interested in protecting their gene pool they would stay with the woman carrying their children. • This evolutionary speculation “reinforces male-female stereotypes.” • We can be socialized to be monogamous or polygamous. • Could be a result of acculturation into family and community structure.

24. Identical twins Fraternal twins Same sex only Same or opposite sex Behavior Genetics • Identical Twins • develop from a single fertilized egg that splits in two, creating two genetically identical organisms • Fraternal Twins • develop from separate eggs • genetically no closer than brothers and sisters, but they share a fetal environment

25. Prenatal Environmental Differences • Separate placentas and blood sources (all fraternal) • b. Share the same placental blood. • Separate placenta twins are somewhat less similar. Why?

26. Behavior Genetics As you know striking similarities have sometimes been found between twins who are reunited after years of separation. What does this mean? Try handout 8 - 1, and be Ready to share your results.