The Nature and Nurture of Behavior

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The Nature and Nurture of Behavior
Even monkeys fall out of trees. Japanese
Proverb The curious paradox is that when I
accept myself just as I am, then I can
change. Carl Rogers
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Lets start with genetics . . .

• Gene
• A stretch of DNA that produces a specific
  protein, which in turn forms building blocks of
  our bodies or drives the processes that allow us
  to live
• DNA (deoxyribonucleic acid) molecule that
  contains genes
• 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
  courtship behavior between two males

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Darwins Natural Selection

• Key is genetic fit with environment
• Mutation
• Depending on environment, genetic makeup or
  organisms evolves throughout generations of
  offspring, producing changes in the dominant
  physical features and behavior of a group of
  organisms

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Evolutionary Psychology

• Using principles of natural selection, focuses on
  the evolution of behavior and the mind
• Mating behaviors
• One of the most studied areas in evolutionary
  psychology
• Why do we find certain characteristics attractive
  in 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 of evolutionary factors
• These differences are more typically seen in
  cultures with gender 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 people are due
  to their genes and how much are due to the
  environment?
• Genes cannot be described in isolation they can
  only 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 on
  heredity
• Earlier temperament predicts later temperament
  and behavior
• Identical twins have more similar temperaments
  than fraternal twins

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Nature vs. nurture?

• The environment has very little effect on
  personality development
• But that doesnt mean that your parents dont
  effect 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
  eventually mate 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 there
  are significant cultural differences present, we
  are still more alike than we are different

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Gender Biologically Speaking

• Until the 7th week of pregnancy, all babies are
  female
• Its the activation of testosterone in a fetus
  that has the XY pair of chromosomes that triggers
  male organ production
• In the fourth fifth months, different brain
  patterns develop due to different levels of
  testosterone 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 through
  social learning