1. Behavior Genetics and Evolutionary Psychology

2. Behavior Genetics and Evolutionary Psychology
Behavior Genetics: Predicting Individual Differences
Genes: Our Codes for Life
Twin and Adoption Studies
Temperament and Heredity
Nature and Nurture
Gene-Environment Interaction

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

4. Behavior Genetics: Predicting Individual Differences
Behavior Geneticists study our differences and weigh the relative effects of heredity and environment.
Preview Question 1: How do behavior geneticists explain individual differences?

5. Genes: Our Codes for Life
Chromosomes containing DNA (deoxyribonucleic acid) are situated in the nucleus of a cell.
Preview Question 2: Our genes predispose our biology; does this mean they determine our behaviors?

6. Genes: Our Codes for Life
Segments within DNA consist of genes that make proteins to determine our development.
Dominant vs. Recessive Genes:
Examples

7. Genome and Phenome . *How ugly you are supposed to be. GENOTYPE
PHENOTYPE .
The genetic makeup, as distinguished from the physical appearance, of an organism or a group of organisms.
*How ugly you are supposed to be.
The observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences.
How ugly you actually are.
--can change your phenotype-colored hair, contacts, etc.. (Punnett Squares)

8. Twin and Adoption Studies: Handout 5-1
Studying the effects of heredity and environment on two sets of twins, identical and fraternal, has come in handy.

9. 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

10. MINNESOTA TWIN STUDY Thomas Bouchard—good name to remember!
Minnesota Twin Studies started in 1979 and continue to this day.
They are given tests that measure their personalities, intelligence, heart rate, brain waves…

11. Minnesota Twin Study Cont.
This study showed examples of similarities.
Jerry and Mark Newman (separated at birth).
Shared characteristics-firefighters, same mustache and sideburns, same glasses, One studied forestry in college-other wanted to but worked for city trimming trees instead.
One installed fire alarms-other installed sprinklers.
Both bachelors and attracted to same type of woman.
Both only drink Budweiser

12. Personality, Intelligence
Separated Twins
A number of studies compared identical twins reared separately from birth, or close thereafter, and found numerous similarities.
Separated Twins
Personality, Intelligence
Abilities, Attitudes
Interests, Fears
Brain Waves, Heart Rate

13. Minnesota Twin Study
Studies show that Identicals have 85% similarity in IQ and Fraternals-60%.
Behavior geneticists say ½ the variation for IQ is because of genetics.
Critics:
Same prenatal environment
Spend avg. of 5 mths together b/f being separated
Avg. of 2 years together before second study.

14. Biological Versus Adoptive Relatives
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.

15. 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?

16. Parenting Influences Children’s
Parenting does have an effect on biologically related and unrelated children.
Parenting Influences Children’s
Attitudes, Values
Manners, Beliefs
Faith, Politics

17. Temperament and Heredity-Handout 5-2
Temperament refers to a person’s stable emotional reactivity and intensity.
Psychologists argue that temperaments are largely inherited based on twin studies: Identical twins express more similar temperaments, in comparison to fraternal twins. Examples: activity, emotionality, sociability

18. 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.

19. The New Frontier: Molecular Genetics
The subfield of biology that studies the molecular structure and function of genes.
Seek to identify specific genes that influence behavior.
Goal is to find those genes that together orchestrate traits such as body weight, sexual orientation, and extraversion.
It also includes the study of chromosomal abnormalities such as Down Syndrome.
**Is it a good idea?Do the benefits (finding cures) outweigh the potential misuse (selective breeding)?

20. Heritability
Heritability refers to the extent to which the differences among people are attributable to genes
If the heritability of height is 90% and you are 60 inches tall does this mean that 54 inches of your height is credited to your genes?
no….. heritability never can be applied to an individual… only groups of people.
As environments become more similar, the heritability of a trait becomes higher

21. Heritability
Hank and Joe are not related. At birth, both were placed in identical environments that were maintained identical until they were 10 years old.
At 10, Hank is withdrawn and shy.
At 10, Joe is outgoing and friendly
In this (very small) population, what is the heritability of their personality traits? In other words, what percentage of the difference is attributable to genes?
Close to 100%

22. Heritability
If this pair of IDENTICAL twins is our population, what percent of the personality differences is attributable to genetic differences between them?
Sarah is outgoing and Sam is shy.
Close to 0%

23. Heritability refers to the extent to which the differences among people are attributable to genes.
If the heritability of height is 90% and you are 60 inches tall does this mean that 54 inches of your height is credited to your genes?
-- no….. heritability never can be applied to an individual… only groups of people.
People with differing heredities who are raised in similar environments will see heritability as a source of differences be higher. Likewise, people with similar heredities who are raised in drastically different environments, heritability is lower.

24. Heritability refers to the extent to which the differences among groups can be explained by genes
As genetics between two groups become more similar….
Heritability is lower (genes can’t explain the difference)
As genetics between two groups become more dissimilar…?
Heritability is higher (genes can explain the difference)
As environments between two groups become more similar…?
Heritability is higher (environment can’t explain the difference, but genes can)
As environments between two groups become more dissimilar…?
Heritability is lower (environment can explain difference)

25. Gene-Environment Interaction
Genes can influence traits which affect responses, and environment can affect gene activity.
Genes are self-regulating: they react to the environment
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.

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

27. Epigenetics
The study of environmental influences on gene expression that occur without a DNA change
--meaning: “In addition to” or “above and beyond” genetics.
--genes have the potential to influence development, environmental triggers can switch them on and off.
Environmental factors such as diet, drugs, and stress can affect the epigenetic molecules that regulate gene expression.

28. Evolutionary Psychology: Understanding Human Nature-Handout 5-3
Evolutionary psychology studies why we as humans are alike. In particular, it studies the evolution of behavior and mind using principles of natural selection.
This approach is helpful in raising the “why of behavior” question that is so central to the discipline of psychology.
Preview Question 3: How do evolutionary psychologists use natural selection to explain behavior tendencies?

29. 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.

30. http://www. ted. com/talks/jim_fallon_exploring_the_mind_of_a_killer

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:
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 do people fear spiders and snakes and not electricity and guns?
How are men and women alike? How and why do men’s and women’s sexuality differ?

33. Question (summarized)
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.
Question (summarized)
Male
Female
Casual sex
58%
34%
Sex for affection
25%
48%
Think about sex everyday
54%
19%

34. Natural Selection & Mating Preferences-Handout 5-4
Natural selection has caused males to send their genes into the future by mating with multiple females since males have lower costs involved.
THERE IS A GENETIC ARGUMENT AS TO WHY MEN ARE “PLAYERS”—just trying to spread their genetic code.
However, females select one mature and caring male because of the higher costs involved with pregnancy and nursing.

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

36. THE COOLIDGE EFFECT
In certain animal species, a male that has become sexually exhausted from repeated copulation with the same female will demonstrate renewed vigor if presented with a succession of new females.
This phenomenon is called the Coolidge Effect b/c of exchange b/w Pres. And Mrs. Calvin Coolidge.

37. COOLIDGE EFFECT-EXCHANGE BETWEEN PRESIDENT AND WIFE
While touring a farm, Mrs. Coolidge was impressed by the untiring sexual activity of one rooster. “You might point that out to Mr. Coolidge” she said. Hearing her remark, Pres. Coolidge asked the farmer whether a different hen was used each time. When informed that this was the case-he said “You might point that out to Mrs. Coolidge.”

38. 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 when they are closely equal, preferences narrow down.

39. 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 do not dictate how we ought to be.
Males and females are more alike than different, and if we study these differences we can establish their causes.

40. ALTRUISM Exercise - Essay by Lewis Thomas Assignment
Is altruism a genetic predetermined factor. Or is it, in the words of Richard Dawkins. “[that] we are born selfish. If we find that human behavior is altruistic, we will be faced with something that needs explaining.”