Transcript Unit 3C Genetics - Teacher Version

Genetics, and Evolutionary
Psychology
3C
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Genetics: Predicting Individual
Differences
Heredity – transmission of physical and
psychological characteristics from parents to
children through genes
Behavior Geneticists - study our differences
and weigh the relative effects of heredity
and environment on behavior and personality.
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Nurture and Human Diversity
Some Environmental Influences:
Parents
Prenatal
Experience
Peer Influence
Culture
Gender
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Genes: Our Codes for Life
Chromosomes – threadlike structures made up of
DNA molecules that contain genes
•Any genetic basis for a trait are located in
chromosomes
•23 from mother and 23 from father
•Located in every cell nucleus
•DNA (deoxyribonucleic acid) – complex molecule
containing the genetic info that makes up the
chromosome.
•Nucleotide – a group of molecules that form the
basic building blocks of DNA
• 4 types
• Adenine and guanine
• Cytosine and thymine
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Genes: Our Codes for Life
Genes - small segments of DNA that are the biochemical
units of heredity.
•Dominant – gene features appear each time gene is
present
•Recessive – features only appear with another
recessive gene
•active - expressed
•inactive - not expressed or dormant (may be
expressed later in a persons life)
• Environmental events “turn on” genes to create protein
molecules
• Self-regulating – genes react to the environment
• African butterfly is green in summer, is brown in fall
• Depression gene – responds to stress and codes for a
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protein that controls serotonin
Genes
• Alleles – two or more variations of a gene
• Can result in different observable
Phenotype traits
• Example: Different eye colors
• Genotypic traits – set of genes responsible
for a specific trait.
• Example: gene(s) responsible for eye
color, baldness, schizophrenia
• Phenotypic traits – visibly expressed traits
– Example: Blue eyes
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Genome
Genome - set of complete instructions for
making an organism, containing all the genes
in that organism.
• human genome makes us human
•the genome for drosophila makes it a
common house fly.
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Mutation
• Mutation – a random error in gene
replication that provides the source
of genetic diversity
– Nature chooses to pass on those that
are most advantageous to survival
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The threadlike structures that
contain genes are called
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2.
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4.
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Genomes
Synapses
Neurons
Chromosomes
Hormones
Table
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DNA is a complex
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Molecule
Synapse
Gene
Genome
Neuron
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The biochemical units of heredity that
make up the chromosomes are called
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Genomes
Molecular genetics
Heredity
Behavior geneticists
genes
Table
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Twins Biology
• Monozygotic
(identical twins) –
one egg and one
sperm
• Dizygotic (fraternal
twins) – two eggs,
two sperm
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Twin Biology
Studying the effects of heredity and environment on
twins
1. Identical twins raised together
- share the same portion of the chromosomes
that determines a single trait or ____________
1. Identical twins raised apart –
same genes, different environment
1. Fraternal twins
– different genes, same environment
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Identical Twins Studies
Twin Studies
Temperament, Intelligence
Abilities, Attitudes
Interests, Fears
Brain Waves, Heart Rate
Caution: any two strangers are likely to share
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coincidental similarities.
IdenticalTwins and IQ
• Bouchard Study
• .69 Correlational
coefficient for IQ tests
of identical twins raised
apart.
• .88 raised together.
Twins and Personality
Temperament - a person’s stable emotional
reactivity and intensity…part of your
personality that you are born with.
•Extroverted (outgoing) & fearless v.
Introverted (shy) & cautious
•Identical twins express similar
temperaments
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Separated Identical Twins and
Personality
•Identical Twins separated at birth – no
extreme differences in personality
•Differences between fraternal twins are
greater than identical twins.
Twin Studies
Temperament, Intelligence
Abilities, Attitudes
Interests, Fears
Bob Sacha
Brain Waves, Heart Rate
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Adoption Studies
•Adoptees - Personalities are different from
their adoptive parents and siblings.
•Environment shared by a family’s children
has relatively no impact on their
personalities
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Personality
• Big 5 Traits
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Extroversion – outgoing
Agreeableness - cooperative and compassionate
Conscientiousness – self-disciplined
Neuroticism – negative emotions
Openness – willingness to experience
new things
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Twins Studies
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Parental Influence
• Parents do influence:
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Attitudes
Values
Manners
Faith
politics
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Heritability
Heritability refers to the extent to which the differences
among people are attributable to genes
Heritability is numerical value with a range from 0.0 to 1.0
0 = genes do not contribute at all to individual differences
 High environmentability
1.0 = genes are the only reason for individual differences
High heritability
 For human behavior, almost all estimates of heritability
are in the moderate range of .30 to .60.
Applies to populations not individuals
100%
Genet
ics
(Natu
re)
90%
Gen.
80%
Gen.
70%
Gen.
60%
Gen.
50-50
60%
Env.
70%
Env.
80%
Env.
90
%
Env
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100%
Enviro
n.
(Nurtu
re)
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Two boys raised in a
barrel with identical
environmental
conditions would have
a heritability of
______?
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Gene-Environment Interaction
Rex Features
People respond differently to
Rowan Atkinson (Mr. Bean) than Orlando bloom.
Alessia Pierdomenico/Reuters/Corbis
•Genes and environment affect our traits
individually, but more important are their
interactive effects.
•Genes are self regulating - genes react to
the environment
•Depression
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The New Frontier:
Molecular Genetics
Molecular genetics is a branch extension of
behavior genetics that asks the question, “Do
genes influence behavior?”
It seeks to identify the specific genes 28
influencing behavior
Studies of identical twins who had been reared apart
most clearly highlight the importance of ________ in
personality development.
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Natural selection
Mutation
Adoptive relatives
Home environments
Genetic predispositions
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Adoptive parents are most likely to influence
the ________ of their adopted children.
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82%
Adult height
Political attitudes
Adult weight
Extraversion
personality
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Heritability refers to the extent to
which
1. Unrelated individuals share
common genes
2. An obtain result occurred by
chance
3. Nurture controls a trait rather than
nature
4. Infant personality determines adult
personality
5. Variation among individuals can
be attributed to their differing
genes
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Molecular genetics seeks to
1. Identify specific genes
influencing behavior
2. Assess the relative
contributions of nature and
nurture
3. Focus mainly on what
makes us so much alike as
humans
4. Treat individuals with
mental disorders
5. Design machines that
interact best with people
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Evolutionary Psychology
Evolutionary psychology - studies the
evolution of behavior and
. mind using
principles of natural selection.
•Adaptive behaviors are those that
promote reproductive success
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Natural Selection
Natural selection - evolutionary process
through which adaptive traits are passed on
to ongoing generations because these traits
help animals survive and reproduce.
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Examples
• Human’s are omnivores
• Pregnant Women Avoid Strongly
Flavored foods
• Children are more valued by biological
father than step father
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Artificial Selection
Artificial Selection - process by which humans breed
other animals and plants for particular traits.
•Belyaev and Trut (1999) - artificially reared and
domesticated wild foxes, selecting them for
friendly traits.
•Any trait that is favored naturally or artificially
spreads to future generations.
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Human Sexuality
Gender Differences in Sexuality
Question (summarized)
Male
Female
Casual sex
60%
35%
Sex for affection
25%
48%
Think about sex everyday
54%
19%
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Mating Preferences
Females
•Select one male because
of the higher costs
involved with pregnancy,
nursing and childcare.
•Look for maturity,
dominance, affluence and
boldness
Males
•Mate with multiple
females to spread
genes
•Look for youthful
appearance and at ages
associated with peak
fertility.
•If older then wants
younger women
•IF teenager then want
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women a few yrs. older
Criticisms of Evolutionary
Psych
• Works backwards to propose and
explanation
• Underestimates cultural
expectations on human sexual
behavior
• Unethical and immoral men could
use explanations to rationalize
behavior toward women
• Does not consider the importance
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of individual choices
• Explain how an evolutionary psychologist
might explain why humans developed into
omnivores, eating both meat and plants.
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