Nature/Nurture

1. Nature v. Nurture
Genetic Influences on Behavior

2. The Nature Argument
(is sometimes compelling)
This guy will never be…. This guy!!!
Why does Brad Pitt look the way he does?

3. Genes: Our Biological Blueprint

4. Genes: Their Location and
Composition
In the nucleus of every cell we have 46 chromosomes……

5. Chromosome Breakdown
Chromosomes DNA
Genes Nucleotides

6. Evolutionary psychology
The science that seeks to explain why
humans act the way they do
Focused on how evolution has shaped
the mind and behavior.
http://www.youtube.com/watch?v=vJdc9zGYVjU

7. Evolutionary Psychology:
Explaining Universal Behaviors
Evolutionary psychology seeks to reconstruct problems that
our ancestors faced in their primitive environments, and the
problem-solving mechanisms they created to meet those
particular challenges.
From these reconstructed problem-solving adaptations, the
science then attempts to establish the common roots of our
ancestral behavior, and how those common behavioral roots
are manifested today in the widely scattered cultures of
the planet.
The goal is to understand human behavior that is universally
aimed at the passing of one's genes into the next
generation.

8. Natural Selection at Work
•1959 Russian Fox story
•40 Males, 100 Females- mated-then
kept only tamest of bunch.
•Mated the tames.
•40 years later--new breed of
fox
•As a result of selective
breeding, the new foxes
became tamer and more dog-like.

9. Evolutionary Psychology at Work
•If we wanted to create a whole population of brainy
teachers, we could take some brainy teachers & have them
mate
•Then have the brainiest offspring mate amongst each
other, and for countless generations keep doing the same
thing.
•After 200 years, what would the population be like or what
are the chances that the 40th generation of offspring be
brainy.

10. Look at our Behaviors…
Can you answer these questions using
evolutionary psychology?
• Why do infants fear strangers when they
become mobile?
• Why are most parents devoted to their
children?
• Why do we divide people into categories?
• Why do we have more phobias about spiders
and snakes than electricity and nuclear
weapons?
Now, the big one?

11. How and why do men and women
differ sexually?

12. Of course, there are other
differences….

13. Sexuality and the Evolutionary
Psychologist
• Casual sex is more
accepted by men.
• When average men
and women randomly
ask strangers for
sex tonight, 75% of
men agreed, almost
no women agreed.
WHY?

14. Sperm is Cheap
Eggs are not

15. What do men and women want?
(According to Evolutionary
Psychology)
Men want:
•Healthy
•Young
•Waist 1/3
narrower than
hips.
Women want:
•Wealth
•Power
•Security

16. Can this change?
http://www.youtube.com/watch?v=UB7ClUNL3Ak

17. Behavior Genetics
The study of the power and
limitations of genes on who
we are.

18. Twin Studies

19. What are the
different
types of
twins?

20. Twin Studies: The results
• To summarize the countless amount of
studies: twins (especially identical), whether
or not they are raised in the same
environment are very much alike in many ways.

21. Temperament Studies
• A person’s
characteristic
emotional
reactivity and
intensity.
• They remain
relatively stable
over time.

22. Heritability
• The proportion of variation among individuals
that we can attribute to genes.
• It is a mathematical formula.

23. Nature v. Nurture
What do you think so far?
Does Nature and Nurture interact
and grow off of each other?
Lets find out soon by examining Nurture in detail….

24. Nurture
Environmental Influences on Behavior

25. Types of Environmental Influences
Parents Prenatal Experience
Peer Influence Culture Gender

26. How Much Credit ( or Blame )
Do Parents Deserve?
Are children clay
to be molded by
their parents?
•You and your siblings grow
up in the same environment,
are you all the same?
•Parents effect your belief
systems and values much
more than your personality.
•Parents take too much
credit for success and too
much blame for failures.
•Extreme environmentalism
can be VERY dangerous,
why?

27. Lets look at perhaps our first environmental influence….
Prenatal Environment

28. Two Placental Arrangements in
Identical Twins

29. Brain cells is an impoverished environment.

30. Brain cells in an enriched environment.

31. What does this mean for humans?
• If children from impoverished
environments given stimulating infant
care, they score better on intelligence
tests by age 12 than counterparts.
Use it or lose it

32. A Trained Brain
A well-learned finger-tapping task activates more
motor cortex neurons (right) than were active in the
same brain before training (left)

33. Peer Influence
•“Selection effect” we
seek out people with
similar interests- that
may explain why we
seem to conform to our
peers.

34. Culture
• Behaviors,
attitudes,
traditions etc…
of a large group
that have been
passed down
from one
generation to
the next.

35. Cultural Variations
• To understand how cultures effect who
we are it is important to recognize our
cultural norms: an understood rule for
acceptable behavior.
• Individual v. Collectivistic Cultures
•Why is it so hard to identify our own cultural norms?

36. Variations over Time
• Different generations of the same
culture may also have differing
norms.

37. Memes
• Self-replicating ideas, fashions
or innovations passed from
person to person.

38. Gender
• We already know the
nature differences.
• XX v XY
• But that focuses on
SEX:
• We are going to
discuss GENDER:
What is the
difference?

39. Gender Roles
• A set of
expected
behaviors for
males and
females
• List some of your
gender roles.
What gender role is she breaking?

40. Changing Attitudes about Gender Roles

41. Gender Identity
• Our own sense of
male or female.
• Personalized to us
• We realize our
gender identity
through gender-typing:
acquiring
our gender
identity.

42. Two Theories of Gender-typing

43. Social Learning Theory
Lets use Sammy as an example.

44. Social Learning Theory
Sammy’s dad
plays Baseball.
Sammy imitates
his behavior.
Dad rewards
Sammy.
Sammy’s Mom
puts on makeup.
Sammy copies her.
Dad punishes
Sammy.

45. Gender Schema Theory
• Schema: a concept or framework of
how we organize information.
• Develop schemas for gender.
• See the world through the lens of
your gender schemas.
Boy’s don’t do this,
that’s for girls.
Yeah, that’s cool!!!!
I want to do that.

46. • Which concept (nature or nurture) do you
agree with and why?