1. Human Behavior
Nature vs. Nurture

2. Nature or Nurture?
Why do men and women have such different attitudes about sex?
Why do boys and girls play with different toys?
Why do you, the oldest, seem to be organized and responsible, while your youngest brother seems to be carefree and happily irresponsible?

3. Behavior Genetics (Text Question #1)
Study individual behavioral differences. (weigh effects of nature, nurture)
Chromosomes: 23 / egg, 23 / sperm (threadlike structures)
Composed of DNA (deoxyribonucleic acid)
Genes: 30,000 each / self-replicating units, synthesize proteins, (the building blocks of physical development
Gene complexes: many genes acting in concert
Genes: Influence physical make-up, intelligence, aggressiveness, happiness etc.

4. Behavior Genetics

5. Nature and Gender Gender Development
What determines male, female offspring
23rd pair of chromosomes determine sex
Female=X, Male = X or Y

6. Fraternal, Identical Twins: What’s the difference?
Fraternal: (dizygotic)
Separate fertilized eggs (50% shared genes- no more genetic similarity than normal siblings)
Identical: (Monozygotic)
Single fertilized egg split in two = clones
(100% shared genes)

7. Fraternal vs. Identical (#2)
Fraternal / Identical twin study findings- provide specifics for the following:
Alzheimer’s
Identical =60% / Fraternal=30%
Extraversion / neuroticism
Identical more similar than fraternal
Divorce rates
Identical x5.5 vs. fraternal x1.6
Schizophrenia
50, 10, 3, 1 (identical, fraternal, sibling, stranger)
What are the limitations of these studies?
Genetics or environment? How do we differentiate?

8. Gerald Levy and Mark Newman Bouchard Minnesota Twin Study

9. Levy and Newman Bouchard’s Minnesota Twin Study
Reunited by shared acquaintance
Upon meeting for first time:
Same mustache, sideburns, glasses
Levey: college degree in forestry- Newman planned to but worked for city trimming trees
Levey worked installing sprinker systems, Newman installed fire alarms
Both were bachelors, same taste in women
Both only drank Budweiser (pinky wrapped underneath can, crushed can afterwards)
Hunting, fishing, beach, John Wayne movies, pro-wrestling, Chinese food in wee hours
Volunteer firefighters
Both raised Jewish, neither particularly religious
When met- same remarks, at same time, same gestures- “spooky”
He is he and I am I, and we are one…

10. Adoption Studies (#5)

11. Environmental relatives / biological Relatives
What insight has adoption studies provided regarding the influence of genetics on personality? (#5)
Environmental relatives / biological Relatives
Finding: subject’s personality reflected biological relatives, even when adopted at birth
Conclusion: people who grow up together don’t resemble each other in personality
Why are two people raised together so different???
Confirmation of genes impact on personality

12. Environmental Influence
So what traits does nurture influence?
Values
Manners
Faith / religion
Politics
Social views

13. Heritability (#6)
Extent to which difference between individuals can be attributed to genes
As environments become more similar, heredity as a source of difference becomes more important (and vice versa)
Heritable differences don’t often translate to group differences

14. Temperament (#7) Our emotional excitability
Temperament traits tend to remain consistent through life
Studies confirm
Genetic temperament helps form enduring personality

15. Nature and Nurture
Genes are self-regulating (respond and adapt to environment)
Individual differences almost always the result of both nature and nurture
“Gene and scene dance together”
Or, “nurture works on what nature endows”

16. Molecular Genetics (#8)
Identify specific genes influence on behavior
Weight, extraversion, sexual orientation…
LD, depression, schizophrenia, alcoholism…
Designer babies?!?!

17. Evolutionary Psychology
Premise
(Darwins’ ) natural selection shapes our behavior, thinking (over time)
Certain traits, behaviors that enhance survival are passed on over generations

18. Questions to Consider
Why do infants start to fear strangers about the time they become mobile?
Why are most parents so passionately devoted to their children?
Why do so many more people have phobias about spiders and snakes than guns and electricity?
Why are men quicker to perceive friendliness as sexual interest?

19. Dmitry Belyaev: Domestication of Foxes

20. Belyaev’s Experiment 30 males, 100 females Tamest 5% M, 20% F
30 generations
Complete domestication
Now sold as house pets
Implications?
When certain traits are selected that give an adaptive advantage, those traits will prevail

21. Gender and Sexual Attitudes / Behavior
Studies:
1978, FSU- research assistants / proposals for casual sex with strangers
75% of men- yes 0% of women- yes
Questionnaire: casual sex with different partners
48% of men- yes 12 % of women- yes
How can we explain this radical difference in sexual attitudes between the genders?

22. Gender Differences and Sexuality Natural selection would suggest that each gender pursued attitudes and behaviors that perpetuated their survival, and thus became part of our DNA over time.
Women- relational
Incubates, nurses one infant
Wants protection, assistance to ensure child’s survival
Chooses wisely
Men- recreational
Perpetuate his genes (spread his genes through other females)
Chooses widely

23. Boys, girls and toys… Nature or Nurture?
Why do genders choose what they do…?

24. Nurture and Gender Nurture influences our sense of gender by…
Gender identity (one’s sense of being male or female)
Gender roles- traditional behaviors, duties of genders
Gender-typing: expectation or assignment of traditional male, female roles
Social learning theory (Observation, imitation)

25. Genes rule…??
In terms of personality, environmental factors typically account for less than 10% of children’s differences. (Key is how parents and peers influence those traits.)

26. Nurture and Early Development
Early experience matters!
Fosters neural connections
Experience preserves activated neural connections
Unused ones degenerate (pruning)
Excess “connectors” in youth make kids more capable of mastering certain tasks.
Example?
Foreign language, (Accent and grammar) visual perception, musical instruments

27. Rat Studies Rosenzweig and Krech Findings:
Isolated, impoverished vs. social, enriched environment
Young rats
Findings:
Obvious differences in behavioral activity and curiosity
Heavier, thicker brain cortex (brain weight increased 7-10 percent and # of synapses increased 20%!)
Impoverished
environment
Rat brain
cell
Enriched

28. Premature Babies Neonatal units Massage therapy stimulates growth
Speeds departure from hospital

29. Nurture’s Sway… Cultural Influences
Individualism
Self: Independent
Life Task: Discover, express one’s uniqueness
What matters: Me, personal achievement, rights, freedoms, self-esteem
Coping method: change reality
Relationships: Many, often temporary, confrontation acceptable
Behavior: Reflects one’s personality, attitude
Collectivism
Self: Interdependent
Life Task: fit in, perform role, obligations
What matters: Us, group goals, family duty, social responsibility
Coping method: Accommodate to reality
Relationships: Few, close and long term, harmony valued
Behavior: social norms and roles

30. Cultural Influences
Individualism
Collectivism