1. Chapter 3 Behavior Genetics

2. The Human Genome Genetic Roadmap Entire genetic code of the human species

3. Genetic Structures DNA - Dioxyribonucleic Acid Genetic Code Genetic Alphabet = 4 Letters –A: Adenine –C: Cytosine –G: Guanine –T: Thymine

5. Genetic “Words” Made up of two strands of DNA molecules Infinite in length (e.g.. ACGCTCTCGA) Because DNA is a Double Helix exact replication is possible Mutations result when “proofreading fails

6. Chromosome Continuous Strands of DNA Locations which have functions are Genes 46 Chromosomes in humans Located as 23 Pairs 22 Pairs are Autosomes 1 Pair are Sex Chromosomes

7. Gene = Location on Chromosome

8. “Parsimony” of Genetics 4 Bases (ACGT) produce enormous diversity Length & uniqueness of ACTG which produces diversity Double helix of DNA allows exact replication during Mitosis Errors in mitosis allows further variability

9. Relative Size of Human Chromosomes

10. Genetic Functions Mitosis: Cell & Genetic Duplication Meiosis: Biparental Reproduction

11. Mitosis = Replication Process

12. Selectionism (Phylogenic & Ontogenic) Requires 3 Mechanisms Variability (Variation) Process for Selection Retention

13. Phylogenic Selectionism Variability –Mutation –Crossing Over –Random Assortment Process of Selection - Natural Selection Retention - Genes

14. Genetic Variablity Random Assortment (Meiosis) Crossing over (Meiosis) Mutations (Meiosis or Mitosis)

15. Random Assortment Occurs during later stage of Meiosis, as gametes are being formed Pairs of chromosomes go to opposite ends of cell 1/2 of chromosomes (1 from each pair) go to new cell (gamete) Which individual of pair is random Produces 1 in 64 trillion chance of duplication This is multiplied by incalculable effects of mutation & crossing-over

16. Genetic Variability Crossing Over Occurs during Meiosis Occurs prior to gamete formation Result is “new” chromosome

17. Genetic Variability - Mutation Error during Mitosis

18. Genetic Variability - Bisexual Reproduction Estimated that each human has the capacity to produce 10 3000 different combinations in gametes Estimated that all the men who ever lived have produced only 10 24 sperm Extremely unlikely that there has ever been a genetic duplicate Exception - Identical (Monozygotic) Twins

19. Genotype = Genetic Make-Up Homozygous –e.g.., BR BR Heterozygous –e.g.., BR bl One allele comes from each parent

20. Alleles - Alternate forms of Genes Produce variability Dominant Gene (allele) Recessive Gene (allele)

21. Phenotype - Expression of Characteristics Expression of –Genotype –Environment –Transaction Examples- –Down Syndrome (Life expectancy of 12) –Height - since 1900-1 cm/decade –Age of Menarche

22. Age of Menarche Norway –1840 - Reached at 17 years –1990 - Reached at 13 years U. S. –1890 - Reached at 14 –1990 - Reached at 12-13

23. Variation in Phenotypes Due to Genotypes Dominant Alleles Recessive Alleles Homozygous Heterozygous Sex-Linked Co-Dominance Incomplete Dominance

24. Genotype = Both Parents Homozygous Dominant (BRBR - BRBR) Genotype Phenotype BR-BR BROWN All Genotypes are homozygous BRBR All Phenotypes are brown (dominant)

25. Genotype=Parents Homozygous recessive (blbl - blbl) Genotype Phenotype blblblue All genotypes are homozygous recessive All phenotypes are blue

26. Genotype=1 Parent homozygous dominant (BRBR) 1 Parent homozygous recessive (blbl) GenotypePhenotype BRblBrown All genotypes are heterozygous All phenotypes are brown

27. Genotype= Both Parents Heterozygous (BRbl - BRbl) Both parent phenotypes are Brown GenotypePhenotype BRBR (Homozygous) Brown BRbl (Heterozygous) Brown blBR (Heterozygous) Brown blbl (Homozygous)blue 3-in-4 chances phenotype will be Brown 1-in-4 chance phenotype will be blue How generation can be skipped

28. Sex-Linked Characteristics Characteristic is recessive Location is on the Y chromosome Male who inherits that recessive (MPB) has no dominant to mask recessive Female who inherits that recessive is likely to have a dominant on other Y These females are “carriers” who may pass Y based recessive to son.

29. Forget It! Human behavior is not single gene Mostly polygenic Genes do not directly produce behavior Genes work through the structures they enable Human Behavior is multifactorial

30. Heritability Genotype Shared Environmental Effects Nonshared Environmental Effects Measurement Error

31. Heritability - Genotype Monozygotic Twins - Identical Genes Dizygotic Twins - Same as siblings Siblings - Share parent gene pool Unrelated children - share broad gene pool

32. Shared Environmental Effects All persons living in same environment Generally very low in heritability estimates

33. Nonshared Environmental Effects Effect on individual No 2 persons (even living together in same house) have same environment Determined by subtracting out Monozygotic twins living in same living situation (e.g..., NS=1.00-.76; NS=.24) –(.76 =genotype + Shared Env. + error)

34. Behavior Results from Interactions (Ross) Genetic Make-Up Interactional History Current Physiological Conditions Current Environmental Conditions Behavioral Dynamics

35. How Do Genes & Environment Interact? Genotype/Environment Effects e.g..., height, weight, muscles, hair color(?), skin color Passive Active Evocative

36. A Behavioral View: Person/Environment Interactions e.g.., clothing, make-up, behavior, skills, hair color? Passive Evocative Active

37. What Canalizes Behavior Canalization – Increasing restriction of outcome as development proceeds Genetic Canalization? Experiential (Environmental) Canalization?