Download Module 3 Nature vs. Nurture - Jackson Liberty Psychology

How do families, friends and culture
affect the way we live?
- Study the
relative effects
of genes and
environment
on behavior
- The nature vs.
nurture debate
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Genes – biochemical units of heredity that
make up a chromosome
Chromosome – Threadlike structures made of
DNA molecules that contain genes (46 total, 23
from each parent)
DNA (deoxyribonucleic acid) – complex
molecule that contains genetic information that
makes up chromosomes
Cell -> Nucleus -> Chromosomes -> DNA ->
Genes
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Genes made up of
nucleotides (A,T,C, or G)
Genome – complete
instructions for making an
organism consisting of all
genetic material in its
chromosomes
Humans have about 30,000
different genes
Does anyone know the
animal humans are most
genetically related to?
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Genes are responsible for predisposing our
appearance and behavior, not concretely
determining either.
Predisposition – a situation that allows
something else to occur but doesn’t necessarily
cause it to occur; “Her genetic makeup left her
with a predisposition to develop Alzheimer's.”
Mutations – random error in gene replication
that lead to a change in genetic code
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Natural selection – the
idea that , among the
inherited trait
variations, those
contributing to survival
will most likely be
passed on to future
generations
Adaptation – species
changing genetically to
better survive in their
environment
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What correlation does economic/social status of a country
have with reproduction rates worldwide if any?
Why do people in poorer countries have more babies?
And should they have more babies?
Is this natural selection at work here? Why or why not?
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Identical twins – twins that develop from a
single fertilized egg and then split in half; are
genetically identical
Fraternal twins – twins that develop from
separate eggs; no more related genetically than
normal siblings
Twin studies have discovered that identical
twins are strikingly similar is intelligence,
attitude and even brain waves!
Fig. 12-14, p. 493
Although they were reared apart from 4 weeks after their birth, Jim Lewis (left) and Jim Springer
(right) exhibit remarkable correspondence in personality. Some of the similarities in their lives—such
as the benches built around trees in their yards—seem uncanny.
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Studies of adopted
children show that they
exhibit similar
personality traits of
their biological parents
However, adopted
children tend to be
smarter, more
productive and more
successful than their
biological parents
Nurture is back in the
game!
Fig. 9-13, p. 353
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Are parents to blame
for success/failure of
children? Studies say
“not really”.
Siblings raised
together tend to be as
different personalitywise as two random
people on the street.
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For our brains to reach
their developmental
potential, early
experience is
CRITICAL.
Children raised in
abusive homes tend to
be less intelligent that
children raised in
loving environments.
Score one for nurture!
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Peers hold a heavy influence on the behaviors
of individuals (i.e. smoking, drinking,
promiscuity )
Bandwagon phenomenon
“Fitting In”
Parents influence behaviors of children by
supplying them the environment from which
they have to work within (i.e. parents “choose”
which neighborhood to live in)
Children, like adults, attempt to fit into a group
by conforming. Peers are influential in such areas
as learning to cooperate with others, gaining
popularity, and developing interactions.
Ole Graf/ zefa/ Corbis
Parenting does have an effect on biologically
related and unrelated children.
Parenting Influences
Children’s
Attitudes, Values
Manners, Beliefs
Faith, Politics
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Culture – shared attitudes and beliefs of a
group passed on from one generation to the
next.
Norms – understood rules for accepted and
expected behavior; prescribe “proper” behavior
Individualism – giving priority to one’s goal
over the goals of the group
Collectivism – giving priority to the group’s
goal over the goal of the individual
Genes can influence traits which affect
responses, and environment can affect gene
activity.
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.
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Height
Temperament
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refers to a person’s stable emotional reactivity and
intensity. Identical twins express similar
temperaments, suggesting heredity predisposes
temperament.
As environments become more similar,
heredity as a source of difference become more
important (since difference due to environment
has decreased).
Genes and environment affect our traits
individually, but more important are their
interactive effects.
Alessia Pierdomenico/Reuters/Corbis
Rex Features
People respond differently to
Rowan Atkinson (Mr. Bean) than Orlando bloom.
Westernized Cultures
Asian-African Cultures
Responsible for your self
Responsible to group
Follow your conscience
Priority to obedience
Discover your gifts
Be true to family-self
Be true to yourself
Be loyal to your group
Be independent
Be interdependent
Despite diverse cultural backgrounds, humans
are more similar than different in many ways.
We share the same genetic profile, life cycle,
capacity for language, and biological needs.
Copyright Steve Reehl
Culture changes over time. The rate of this change may
be extremely rapid. In many Western countries,
culture has rapidly changed over the last 40 years. This
change cannot be attributed to changes in the human
gene pool because genes evolve very slowly.
Based on genetic makeup, males and females
are alike, since the majority of our inherited
genes (45 chromosomes are unisex) are similar.
Gender is determined by only one chromosome.
Males and females differ biologically in body
fat, muscle, height, onset of puberty, and life
expectancy.
Biological sex is determined by the twenty-third pair
of chromosomes. If the pair is XX, a female is
produced. If the pair is XY, a male child is produced.
In the mother’s womb, the male fetus is exposed
to testosterone (because of the Y chromosome)
which leads to the development of male
genitalia.
If low levels of testosterone are released in the
uterus, the result is female.
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The average…than the average man.
woman begins puberty 2 years earlier
woman lives 5 years longer
woman has 70% more body fat and tend to carry it in
different areas of the body
woman has 40% less muscle
woman is 5” shorter
woman is far less likely to be colorblind
woman is doubly vulnerable to depression and anxiety
woman’s risk of developing an eating disorder is 10x
greater
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The average man is 5x more likely to commit
suicide or suffer alcohol dependence than the
average woman.
The average man is more likely to develop
autism, ADHD or personality disorder than the
average woman.
Men express themselves and behave in more
aggressive ways than do women. This
aggression gender gap appears in many
cultures and at various ages.
In males, the nature of this aggression is
physical.
In the US, the male-to-female arrest ratio for
murder is 10:1.
In most societies, men are socially dominant
and are perceived as such.
In 2005, men accounted for 84% of the
governing parliaments.
Young and old, women form more connections
(friendships) with people than do men. Girls tend to
play in smaller groups with more intimate
relationships. Boys emphasize competition, freedom
and self-reliance while playing in larger groups.
Dex Image/ Getty Images
Oliver Eltinger/ Zefa/ Corbis
Our culture shapes our gender roles —
expectations of how men and women are
supposed to behave.
Gender Identity — means how a person views
himself or herself in terms of gender.
1. Social Learning Theory proposes that we
learn gender behavior like any other
behavior—reinforcement, punishment, and
observation.
2. Gender Schema Theory suggests that we
learn a cultural “recipe” of how to be a male
or a female, which influences our genderbased perceptions and behaviors.
Evolutionary psychology studies why we as humans are
alike. In particular, it studies the evolution of behavior
and mind using principles of natural selection.
The following traits would benefit humans in that they
would provide an advantage for survival and
reproduction:
 The mental capacities for acquiring language.
 The ability to infer emotion in others and to cooperate
with others.
 The preference for healthier, more fertile mates.
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No more than 5% of the genetic differences
among humans arise from population group
differences. Therefore, 95% of genetic variation
exists within populations.
The typical genetic difference between two
Icelandic villagers or between two Kenyans is
much greater than the average difference
between to the two groups.
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?
Gender Differences in Sexuality
Males and females, to a large extent, behave
and think similarly. Differences in sexes arise in
regards to reproductive behaviors. In the U.S.:
Question (summarized)
Male
Female
Casual sex
58%
34%
Sex for affection
25%
48%
Think about sex everyday
54%
19%
Natural selection has caused males to send their
genes into the future by mating with multiple
females since males have lower costs involved.
However, females select one mature and caring
male because of the higher costs involved with
pregnancy and nursing.
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.
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Men are typically more attracted to a woman
whose waists are roughly a third narrower
than their hips – a sign of future fertility.
Men are attracted to women who are at the age
of peak fertility (which has shifted over time).
Women are more attracted to men who seem
more mature, dominant, bold and affluent.
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.
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.