Chapter 3 - Nature and Nurture
Reading Map
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99-107
108-113
113-116
116-125
in class essay
126-end and review
126 – end and review
Quiz/cards/study guide
Web Site
• http://bcs.worthpublishers.com/myers10e/#
746145__765314__
Genes: Our Biological Blueprint (100)
• Human genome researchers know the common
sequence of 3.1 billion letters within human DNA
• Humans and chimps share 95% of our letter
sequences
• Humans to humans share about 99.0% of our
DNA sequences
• Every cell nucleus in your body contains the
genetic master code for your entire body
Chromosomes/DNA/Genes/Nucleotides
• 46 chromosomes (23 from
mom/23 from dad)
• Chromosomes are made of
DNA molecules
• Small segments of DNA are
called genes
• We have about 30,000 genes
• Our genes are composed of
nucleotides (ATCG) - the
smallest gene (Y) has 50
million nucleotide letters - the
largest has 250 million
• Nucleotide (letters) – genes
(words) – DNA (pages) –
Chromosomes (book)
Evolutionary Psychology (101)
• Studies how natural
selection favored
behavioral tendencies
that contributed to the
survival and spread of
our ancestor’s genes
• Dead people don’t
have babies!
Belyaev and Trut
• 40 year fox
experiment
• selected tames foxes to
breed for 30
generations
• Result- tame foxes
• Principle - trait
selection
Teacher Guide References
• Handout 3-2 - Evolutionary Psychology
Questionnaire
• TG 3-8 - evolution of bedtime tantrums in
children
Natural Selection (102)
• The principle that, among
the range of inherited trait
variations, the traits that
lead to increased
reproduction and survival
will most likely be passed
on to future generations
• BUT, genes and
experience (our ability to
adapt) wire our brain.
Evolutionary Psychology (103)
• The study of the evolution
of behavior and the mind,
using principles of natural
selection.
• We are predisposed to
behave in ways that
promoted our ancestor’s
surviving and
reproducing.
• See evolutionary questions
on page 103
•
TG 3-11 - the Coolige Effect
Sexuality and Gender Differences (104)
• Gender -biologically or socially influenced
characteristics that define male/female
• Baumeister, Catanese, Vohs (2001) - men think
about sex, initiate sex, make sacrifices for sex
more than women
• Clark and Hatfield (1989) - “average looking”
researchers approach strangers and suggest sex all women refuse - 75% of men agree to it
• Abbey (1987) - men misperceive women’s warm
responses as sexual come-ons
• Many studies show a male/female difference in
sexuality ----- why?
Sexuality: An Evolutionary
Explanation (104)
• Natural selection explains women’s
relational approach to sex and men’s
recreational approach
• Our females ancestors produced only one
child at a time so they were more careful
with whom they paired
• Our males ancestors could reproduce with
many women at the same time
Attractiveness and Evolution (104)
• Men look for healthy,
young, fertile mates
• Women look for
healthy, mature,
dominant, bold and
rich mates
• We still advertise
these qualities - check
out the companions
wanted ads!
Critiquing Evolutionary Theory (106)
• It starts with the effect (ex. Gender differences in
sex) and works backwards to explain it
• What about alternative theories?
• Fails to explain some species (ex. Chimps) where
females mate with multiple males
• Could our mating preferences be more influenced
by family, culture?
• Could it be used to excuse bad behavior?
Behavior Genetics (108)
• Study our individual differences
• They research genetic and environmental
contributions to our various traits
• They often use twin and adoption studies to
study genetic and environmental factors
Twin Studies (108)
• Identical twins genetically identical
because one egg splits
• Fraternal twins - two
eggs - genetically are
no more alike than
normal siblings -
Identical Twin Studies (108)
• More similar in extraversion and introversion
• McGue and Lykken (1992) - divorced fraternal
twin increases odd for the other twin divorcing by
1.6 times. Divorced identical twin odds go up to
5.5 times
• Loehlin and Nichols (1976) identical twins treated
alike by their parents are no more similar in
personality than twins treated differently
Separated Twins (109)
• Separated twins reared in different types of homes
end up with similar traits, tastes, abilities,
attitudes, etc
• If parents think an identical pair is fraternal, the
identical pair still turns out as similar as other
identical twins
• 9 min clip on separated twins
http://www.youtube.com/watch?v=1gwnzW4jOM
I
Twins???
Adoption Studies (111)
• Do adopted children have the traits of their
biological or adoptive parents?
• Personality traits - like biological parent
• Attitudes, values, manners, faith, politics like adoptive parents
• And, siblings also tend to have unique
personalities even though raised in the same
home by shared parents.
Adoption Studies (111)
• Benson (1994) - adopted children tend to thrive,
especially when adopted as infants
• Sharma (1998) - adopted children score higher
than their biological parents on intelligence tests.
7 out of 8 report feeling attached to 1 or both of
their adopted parents. They also grow up to be
more self-giving and altruistic than average
• Bohman (1990) - adopted children end up with
fewer problems than those who were going to be
adopted but ended up being kept by their
biological parents
Temperament (112)
• Temperament is our inborn emotional
excitability (reactive/easygoing;
intense/quiet/; fidgety/placid)
• Shows up in first weeks of life
• Temperament Persistence
• Goodness of Fit (parent plus infant
temperament – do they work well together?)
• Genetic - identical twins are more similar in
temperament
• Chess and Thomas (1970) - difficult, easy
and slow to warm temperaments
Heritability (112)
• The extent to which VARIATION among
individuals can be attributed to their differing
genes.
• NOTE - it doesn’t mean what % of an individual’s
trait is inherited
• Ex - boys in a barrel - if their IQ’s differ we say it
is nearly 100% heritability since their
environments were identical.
• As environments become more similar, heredity as
a source of differences necessarily becomes more
important.
Group Differences (113)
• Heritable
individual
differences need
not imply
heritable group
differences.
Nature Enables Nurture (113)
• Our most important similarity is our ability to
adapt
• Environment reacts to and shapes what nature
predisposes
• Psychological traits are usually the result of both
genetic and environmental factors
• Our genetic traits (ex. good looking) evoke
responses from our environment
• We select environments to suit our predispositions
Molecular Genetics (115)
• Study of specific
genes and how they
influence behavior
• Most traits have a
team of genes
• Genetic tests reveal
who is a risk for
certain diseases
• Issues???????
Environmental Influences (116)
Prenatal Nutrition
Environment
Parents
Peers
Early Stimulation
Culture
Environment (117)
• Behavior geneticists find that shared
environmental influences (home) account
for less than 10%of children’s personality
differences.
• Two children in the same family are as
different as are pairs of strangers
• BUT, the environment does effect values
and beliefs
Prenatal Environment (118)
• Nurture begins in the
womb
• Nutrition and toxins
• Identical twins with share
placenta have more
similar psychological
traits than those identical
twins with separate
placentas (Phelps 1997)
Experience and Brain
Development (118)
• Experiences help develop
brain’s neural connections
• Rosenzweig and Krech
(1987) - rats in solitary
had light and thinner brain
cortexes than those raised
in enriched environments
• Kolb and Whishaw (1998)
after 60 days of an
enriched environment rats
brain weight increased
10% and the number of
synapses increased 20%
Use it or Lose It (118)
• After brain maturation provides us with an
abundance of neural connections,
experience preserves our activated
connections while allowing our unused
connections to degenerate.
• Critical Period - the period in our life where
we will best and most easily learn - example
- early childhood language development -
Peer Influence (120)
• Harris (1998) argues that
peer influence may exceed
parental
• Gardner (1998) argues
parents and peers are
complementary. Parents
shape education,
discipline, responsibility.
Peers shape cooperation,
popularity, interaction
styles.
Peer Influence
• Selection Effect - kids
seek out peers with
similar attitudes and
interests
• Evolutionary
perspective - nature
predisposes teens to be
heavily influenced by
peers
Culture (121)
• Culture is the
behaviors, ideas,
attitudes and traditions
shared by a large
group of people and
transmitted from
generation to
generation
Culture
• Cultural Norms - rules of accepted and expected behavior
• Personal Space - buffer zone around our bodies - differs
from culture to culture
• Communication style - how we say it is as important as
what we say - Iraq war comment example p 123
Culture - Variation Over Time (123)
• Meme - a selfreplicating idea,
fashion, innovation
passed from person to
person
Culture and Child Rearing (124)
• Child rearing varies from culture to culture
• Child “values” also vary - do we want
obedient children or creative children?
• Children of communal cultures have a
stronger sense of their “family” self (what
shames the child shames the family).
• Children of western cultures have a stronger
sense of their independent self
Development Similarities (124)
• Shared biology
• Shared life cycle
• Shared developmental
processes
• Shared response to
parenting styles
Gender (126)
• We do not take on gender
until 7 weeks after
conception when the 23rd
pair of chromosomes
gives us either an XX or
an XY
• Mothers contribute x
• Fathers contribute x or y
Gender
• In the 4th and 5th month the fetus’ brain
development is influenced by M and F
hormones
• Hines and Green (1991) Female rats and
monkeys exposed to prenatal testosterone
will look more masculine and act more
masculine (aggressive)
Gender (127)
• Gender = biology
• Gender is also socially
constructed
• Role - group of prescribed
actions for a person of a
certain social status
• Gender Role - expected
behaviors or M and F
• Culture/Time/Generations
shape gender roles
Gender Identity (128)
• Gender Identity - our
sense of being male or
female
• Gender Type acquiring traditional
M or F roles
Gender Theories (128)
• Social Learning
Theory - We observe
and imitate behavior
and are rewarded or
punished for certain
behaviors. Through
this we form our sense
of gender.
Gender Theories
• Social-Cognitive
Theory - we imitate
and are
rewarded/punished
BUT we also have our
own gender ideas that
shape our gender
Gender Theories (129)
• Gender Schema
Theory - you have a
gender schema (a
lens)through which
you view your social
world - this shapes
your gender formation