Part 5 (Nature-Nurture)

PART 5
© T.G. Lane 2018
SECTIONS
NATURE, NURTURE, AND HUMAN
DIVERSITY
Ѱ
5
Psychology, Twelfth Edition (Myers, D. G.)
1 BEHAVIOR GENETICS: PREDICTING INDIVIDUAL DIFFERENCES
2 EVOLUTIONARY PSYCHOLOGY: UNDERSTANDING HUMAN NATURE
3 HOW DOES GENDER INFLUENCE DEVELOPMENT?
4 CULTURAL INFLUENCES
5 GENDER DEVELOPMENT
6 REFLECTIONS ON NATURE AND NURTURE

NATURE, NURTURE, AND HUMAN DIVERSITY
LEARNING OBJECTIVES
• Discuss how the major components of human chromosomes
function
• Discuss how twin studies can be used to determine whether
human traits and psychological behavior are more heavily
influenced by the environment or by heredity.
• Provide scholarly explanations for how identical twins
can differ physically and psychologically
PART5:NATURE,NURTURE,ANDHUMAN
DIVERSITY
• Discuss how molecular genetics research can be used to
prevent the onset of specific psychological disorders
• Discuss how heredity and environment work together
© T.G. Lane 2018

LEARNING OBJECTIVES
• Discuss how the field of epigenetics can help to explain the
onset or prevention of specific genetic expressions
• Discuss how evolutionary psychologists use natural selection
to explain similar human behavior tendencies
• Discuss how early experiences modify the human brain
• Discuss how cultural norms influence human behavior
• Discuss what is included in the biopsychosocial approach to
development
© T.G. Lane 2018
DIVERSITY

NATURE, NURTURE, AND HUMAN DIVERSITYPART5
SECTION
PREDICTING INDIVIDUAL
DIFFERENCES
BEHAVIOR GENETICS:
© T.G. Lane 2018

BEHAVIOR GENETICS: PREDICTING INDIVIDUAL DIFFERENCES1
What are genes and how do behavior geneticists explain our
individual differences?
1:
+
• Behavior geneticists study human differences and weigh the
effects and interplay of heredity and environment.
• behavior genetics: the study of
the relative power and limits of
genetics and environmental
influences on behavior
• environment: every
nongenetic influence, from
prenatal nutrition to the
people and things around us
© T.G. Lane 2018
DIVERSITY

1
GENES: OUR CODES FOR LIFE
• In humans, each cell normally
contains 23 pairs (totaling 46) of
chromosomes– each chromosome
is composed of DNA. Genes make
up a small segment of the giant
DNA molecules.
• chromosomes:
threadlike structures
made of DNA molecules
that contain the genes
• DNA: complex molecule
containing the genetic
information that makes
up the chromosomes
BEHAVIOR GENETICS: PREDICTING INDIVIDUAL DIFFERENCES
© T.G. Lane 2018
DIVERSITY

1
GENES: OUR CODES FOR LIFE
• genes: the biochemical units of
heredity that make up the
chromosomes which is a small
segment of DNA
Human genome researchers have discovered
the common sequence within human DNA;
they are interested in occasional variations
found at particular genes sites in human
DNA.
• genome: complete instruc-
tions for making an organism,
consisting of all the genetic
material in that organism’s
chromosome
© T.G. Lane 2018
DIVERSITY

1
TWIN AND ADOPTION STUDIES
Identical Versus
Fraternal Twins
How much is a trait determined by
our genes?
COMPARISON
(geneticsvs.environment)
Fraternal
Twins
Identical
Twins
VideoClipVideoClip
© T.G. Lane 2018
DIVERSITY

1
Identical Versus Fraternal Twins
Identical
Twins
RESEMBLE
EACHOTHER
Fraternal
Twins
RESEMBLE
EACHOTHER
~
Identical
Twins
RESEMBLE
EACHOTHER
Fraternal
Twins
DOESNOTRESEMBLE
EACHOTHER
~
Twin studies compare several pairs of
identical twins with fraternal twins to
determine whether traits result from
environmental or genetic factors.
© T.G. Lane 2018
DIVERSITY

1
Identical Versus Fraternal Twins
• The fact that both identical twins
in a pair do not possess a trait or
develop a particular disease
100% of the time indicates that
there are other factors involved.
• Twins share many aspects of
their environment (e.g. uterine
environment, parenting style,
education, wealth, culture, etc.)
by virtue of being born in the
same time and place; environ-
mental differences can exist.
© T.G. Lane 2018
DIVERSITY

1
Separated Twins/Biological Versus Adoptive Relatives
Identical
Twins
• In some domains it appears as though
identical twins reared apart are just as
similar as identical twins reared toget-
her (i.e. sharing similar interests, habits,
etc.).
• Studies indicate that people who grow
up together, whether biologically related
or not, do not much resemble one
another in personality– suggesting
genetics as the influence; parents how-
ever do influence children’s attitudes,
values, manners, faith, and politics.
© T.G. Lane 2018
DIVERSITY

1
Temperament
Heredity predisposes one’s temperament
within the first few weeks of birth.
• temperament: emotional reactivity and
intensity; emotional excitability inhibited
Temperament tends to remain consistent
throughout childhood and in some cases
throughout adulthood; environmental factors
may change this aspect of one’s personality.
© T.G. Lane 2018
DIVERSITY

1
THE NEW FRONTIER: MOLECULAR GENETICS
What is the promise of molecular genetics research?2:
Behavior geneticists are interested in
molecular genetics for determining
which specific genes influence behavior
• molecular genetics: the
subfield of biology that
studies the molecular
structure and function of
genes
Behavior geneticists aim to use
DNA to predict risk (like diseases)
so that steps can be taken to prevent
problems (such as specific environmental
factors) before they happen
© T.G. Lane 2018
DIVERSITY

1
• stomach-to-brain (“I’m full”)
• amount of fuel the muscles need
• number of calories burned off by
being active
• efficiency of the body of converting
extra calories into fat
BODY WEIGHT (several genes have influence)
Most human traits are influenced by teams
of several genes, not by one gene alone
THE NEW FRONTIER: MOLECULAR GENETICS
Example:
Could DNA-scanning techniques lead parents to discriminate
against their children (e.g. boys vs. girls, learning disabilities, etc.)?
© T.G. Lane 2018
DIVERSITY

1
GENE-ENVIRONMENT INTERACTION
How do heredity and environment work together3:
• Some human traits are expressed
(activated) only in particular
environments; genes react (e.g. similar
to a butterflies’ genetic switch to change
colors during different seasons).
• Nature and nurture interact;
environments trigger genetic
activity.
• Genes for depression do not cause depression but instead
regulate neurotransmitters involved in depression which
can be thrown off by environmental circumstances.
© T.G. Lane 2018
DIVERSITY

1
Genes can be either active (expressed) or
inactive (switched on or off); epigenetics
aims to investigate how genes are
triggered.
• epigenetics: the study of influ-
ences on gene expression that
occur without a DNA change
An organic methyl molecule is a type of
epigenetic mark that attaches to part of a
DNA strand (instructs the cell to ignore any
gene present in that DNA stretch– making
it inactive) – e.g. stress hormones blocked.
© T.G. Lane 2018
DIVERSITY

1BEHAVIOR GENETICS: PREDICTING INDIVIDUAL DIFFERENCES
Molecular geneticists are teaming
with psychologists to pinpoint
genes that put people in risk for
such genetically influence dis-
orders like:
• learning disabilities
• depression
• schizophrenia
• alcohol dependence
Video Clip
© T.G. Lane 2018
DIVERSITY

PART5
SECTION
UNDERSTANDING HUMAN
NATURE
EVOLUTIONARY PSYCHOLOGY:
© T.G. Lane 2018

2EVOLUTIONARY PSYCHOLOGY: UNDERSTANDING HUMAN NATURE
NATURAL SELECTION AND ADAPATATION
How do evolutionary psychologists use natural selection to explain
behavior tendencies?
4:
Evolutionary psychologists focus mostly
on what makes humans so much alike.
• evolutionary psychology: the study
of the evolution of behavior and
the mind, using principles of
natural selection
© T.G. Lane 2018
DIVERSITY

• natural selection: the principle
that, among the range of inherited
trait variations, those that lead to
increased reproduction and
survival will most likely be passed
on to succeeding generations
• mutation: a random
error in gene replic-
ation that leads to
change
Humans’ adaptive flexibility in responding to different environments
contributes to one’s fitness– one’s ability to survive and reproduce.
© T.G. Lane 2018
DIVERSITY

Examples
• Pregnant women avoiding
bitter, strong flavored, novel
foods (toxic to embryonic
development)
• “Universal moral grammar”
(e.g. vent with lethal gas leak)
• Love for sweets and fats, which
prepare human ancestors to
survive famines
Video Clip
© T.G. Lane 2018
DIVERSITY

PART5
SECTION
HOW DOES EXPERIENCE
INFLUENCE DEVELOPMENT?
© T.G. Lane 2018

HOW DOES EXPERIENCES INFLUENCE DEVELOPMENT?3
How do early experiences modify the brain?5:
EXPERIENCE AND BRAIN DEVELOPMENT
• Human genes dictate one’s overall brain architecture, but ex-
perience fill in the details, developing neural connections and
preparing one’s brain for thought and language and other later
experiences; touch also benefits premature babies.
Use it or lose it.
• Both nature and
nurture sculpt
human synapses.
© T.G. Lane 2018
DIVERSITY

CULTURAL INFLUENCES4
How do cultural norms affect our behavior?6:
VARIATIONS ACROSS CULTURES
• Nature’s great gift to humans is one’s ability to learn and
adapt. Depending on the circumstances, humans may need
to be able to adapt to different cultures.
• culture: the enduring behaviors, ideas,
attitudes, values, and traditions shared
by a group of people and transmitted
from one generation to the next
• Human nature manifests human diversity.
• Culture shapes human lives.
© T.G. Lane 2018
DIVERSITY

• norms: an understood rule for
accepted and expected behavior;
prescribes “proper” behavior
• Individuals may exper-
ience culture shock when
they don’t understand
what’s expected or
accepted.
Humans in varied cultures share some basic moral ideas yet each
cultural group also evolves its own norms.
VARIATIONS ACROSS CULTURES
Video Clip
© T.G. Lane 2018
DIVERSITY

Similarities Across Cultures:
Mindful of how others differ from us, individuals often fail to
notice the similarities predisposed by individuals’ shared biology.
DEVELOPMENTAL SIMILARITIES ACROSS GROUPS
• personality traits (i.e., conscientiousness
and extraversion)
• supported children feel better about
themselves
• academic achievement
• biological attributes and needs (e.g.,
language, hunger, etc.)
© T.G. Lane 2018
DIVERSITY

GENDER DEVELOPMENT5
GENDER DIFFERENCES AND SIMILARITIES
DIFFERENCES SIMILARITIES
- overall self-esteem
- facing similar adaptive challenges
(e.g. intelligence, learning, memory)
- tend to seek understanding from
one’s mother when expressing
worry and hurt
- women are doubly vulner-
able to depression and
anxiety
- men tend to be more agg-
ressive
- women tend to use conver-
sation to explore relationships;
men tend to use conversation
to explore solutions
- women tend to feel better
about their behavior and
ethics
- men are more susceptible
to alcoholism and suicide
© T.G. Lane 2018
DIVERSITY

THE NATURE OF GENDER: OUR CULTURE
GENDER DEVELOPMENT
How do gender roles and gender typing influence gender devel-
opment?
7:
Although biologically influenced, gender is also socially constructed.
• Roles are often defined by society
(e.g. gender roles); these behaviors
are expected of those who occupy a
particular social position.
• gender roles: a set of expected
behaviors for men and women
5
© T.G. Lane 2018
DIVERSITY

THE NATURE OF GENDER: OUR CULTURE
GENDER DEVELOPMENT
Some researchers suggest that the social learning theory is a good
explanation for children’s learned gender identity, while others argue
that modeling and rewarding of male-female differences aren’t
enough to explain gender typing.
• social learning theory: the idea
that behavior is learned by
observation/modeling
• gender typing: the acquisition
of a traditional masculine or
feminine role
5
© T.G. Lane 2018
DIVERSITY

6
What is included in the biopsychosocial approach to development?8:
REFLECTIONS ON NATURE AND NURTURE
© T.G. Lane 2018
DIVERSITY

Part 5 (Nature-Nurture)

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