Download here

1
Behavior Genetics: Predicting
Individual Differences
 Genes: Our Codes for Life
 Twin and Adoption Studies
 Temperament and Heredity
 Nature and Nurture
 Gene-Environment Interaction
2
Evolutionary Psychology:
Understanding Human
Nature
 Natural Selection
 An Evolutionary Explanation of
Human Sexuality
3
Behavior Geneticists study our differences and
weigh the relative effects of heredity and
environment.
4
Chromosomes containing DNA (deoxyribonucleic
acid) are situated in the nucleus of a cell.
5
Segments within DNA consist of genes that
make proteins to determine our development.
Dominant vs. Recessive Genes:
Examples
6
GENOTYPE
.
PHENOTYPE
 The observable physical or
 The genetic makeup, as
biochemical characteristics of
an organism, as determined
by both genetic makeup and
environmental influences.
distinguished from the
physical appearance, of an
organism or a group of
organisms.

How ugly you are supposed
to be.


How ugly you actually are
You can change your
phenotype-colored hair,
contacts, etc..
https://youtu.be/prkHKjfU
mMs
7
Studying the effects of heredity and
environment on two sets of twins, identical and
fraternal, has come in handy.
8
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
9



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…
10
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
 The Jim Twins



11
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
12






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.
13
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.
14
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?
15
Parenting does have an effect on biologically
related and unrelated children.
Parenting Influences
Children’s
Attitudes, Values
Manners, Beliefs
Faith, Politics
16
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.
18

The extent to which differences in the
appearance of a trait across several people
can be accounted for by differences in their
genes.
 Correlational term—only positive value (0 to 1)


Heritability IS NOT the same as inherited
https://www.khanacademy.org/testprep/mcat/behavior/behavior-andgenetics/v/heritability
19

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.
**Is it a good idea?Do the benefits (finding
cures) outweigh the potential misuse (selective
breeding)?

22
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.
23
Natural selection is an evolutionary process
through which adaptive traits are passed on to
ongoing generations because these traits help
animals survive and reproduce.
24

http://www.ted.com/talks/jim_fallon_explori
ng_the_mind_of_a_killer.html
25
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: 160-169
Any trait that is favored naturally or artificially
spreads to future generations.
26
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?
27
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%
28
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.
29
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.
30


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.
31

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.”
32
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.
33
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.
34