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The Nature and Nurture ofBehavior
Even monkeys fall out of trees.
Japanese Proverb
The curious paradox is that when I acceptmyself just as I am, then I can change.
Carl Rogers
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Let’s start with genetics . . .
Gene
A stretch of DNA that produces a specific protein, which in
turn forms building blocks of our bodies or drives theprocesses that allow us to live
DNA (deoxyribonucleic acid): molecule that containsgenes
Human instruction manual: genes affect physical features,such as eye color and height, and behavior
Dogs are bred for genetic disposition/behavior
One gene in fruit flies can be altered to produce courtshipbehavior between two males
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Darwin’s Natural Selection
Key is genetic fit with environment
Mutation Depending on environment, genetic makeup or
organisms evolves throughout generations ofoffspring, producing changes in the dominant
physical features and behavior of a group oforganisms
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Evolutionary Psychology
Using principles of natural selection, focuseson the evolution of behavior and the mind
Mating behaviors
One of the most studied areas in evolutionarypsychology
Why do we find certain characteristics attractivein a potential mate?
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Evolutionary Psychology –
Gender Differences in Attraction Women prefer economic resources & older partners
Men prefer physical attractiveness & younger
partners
These differences may arise from the different social
roles the genders have historically held or because ofevolutionary factors
These differences are more typically seen in cultures withgender inequalities
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Criticisms of Evolutionary
Explanations Evolutionary theories are circular and
sometimes untestable
Alternate explanation
Overall, women have fewer resources(Ganestead, 1993)
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Behavioral Genetics
How much of the differences among peopleare due to their genes and how much are dueto the environment?
Genes cannot be described in isolation: they canonly be characterized in relation to the
environments in which they operate
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Twin studies
Identical twins Zygote splits (monozygotic)
Fraternal twins Two separate zygotes (dizygotic)
Adoption studies Compared adopted kids with biological and
adopted parents
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Temperament Studies
Examining how emotionally excitable an infant is
‘Easy’ babies are cheerful, relaxed & predictable
‘Difficult’ babies are more irritable, intense &unpredictable
Temperament is mostly stable and mostly based onheredity
Earlier temperament predicts later temperament and behavior
Identical twins have more similar temperaments than fraternaltwins
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Nature vs. nurture?
The environment has very little effect onpersonality development
But that doesn’t mean that your parents don’teffect you at all
Their influence can be seen in your attitudes, values,
manners, religion, and politics Most behaviors/traits are an interaction of
your genes and the environment
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Environmental Influence
Should we really blame the parents?
NO in the environmental sense and YES in the
genetic sense
Experience and brain development
Use it or lose it, especially early on
Peer influence Parents are necessary for early childhood survival –
peers are necessary for lifelong survival
Peers are who we play with, work with, and eventuallymate with
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Cultural Influence
Culture
The behaviors, ideas, attitudes, and traditions
shared by a large group of people Norms: the rules for accepted and expected
behavior (based on group membership)
Regardless of the cultural norms of a group, most
are very successful at raising children
One important consideration is that while thereare significant cultural differences present, weare still more alike than we are different
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Gender – Biologically Speaking
Until the 7th week of pregnancy, all babies arefemale
It’s the activation of testosterone in a fetus thathas the XY pair of chromosomes that triggersmale organ production
In the fourth & fifth months, different brainpatterns develop due to different levels oftestosterone and ovarian hormones
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Gender – Socially Speaking
Gender roles
The expectations about how men and women
behave In nomadic cultures, there is minimal gender role
occurrence
Boys and girls experience the same upbringing
In agricultural societies (of which ours originated),there are strict gender role structures in place
Most of our gender identity is acquired throughsocial learning