The Nature and Nurture of Behaviour

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Chapter 3

• The Nature and Nurture of Behaviour

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Genes Our Biological Blueprint

• Chromosomes
• threadlike structures made of DNA that contain
  the genes
• DNA (deoxyribonucleic acid)
• complex molecule containing the genetic
  information that makes up the chromosomes
• has two strands-forming a double helix- held
  together by bonds between pairs of nucleotides

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Genes Our Biological Blueprint

• Genes
• biochemical units of heredity that make up the
  chromosomes
• a segment of DNA capable of synthesizing a
  protein
• The paradox 30,000 genes for 300,000 proteins
• Genome
• the complete instructions for making an organism
• consisting of all the genetic material in its
  chromosomes

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Evolutionary Psychology

• Natural Selection
• the principle that, among the range of inherited
  trait variations, those contributing to survival
  will most likely be passed on to succeeding
  generations
• Mutations
• random errors in gene replication that lead to a
  change in the sequence of nucleotides
• the source of all genetic diversity

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Evolutionary Psychology

• Evolutionary Psychology
• the study of the evolution of behavior using the
  principles of natural selection
• Behaviour expressed prior age of mating can
  possibly be selected for by natural selection
• Gender
• in psychology, the characteristics, where
  biologically or socially influenced, by which
  people define male and female

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Evolutionary Psychology

• Men everywhere preferred attractive physical
  features suggesting youth and health

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Behavior Genetics

• Behavior Genetics
• study of the power and limits of genetic and
  environmental influences on behavior
• Environment
• every nongenetic influence, from prenatal
  nutrition to the people and things around us

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Romanian Orphanages

• Elinore Ames (1997) study
• Early deprivation and malnutrition
• When adopted before 4 months there seem to be no
  long term consequences
• When adopted after 8 months or more they were
  developmentally delayed (could not walk or talk
  at 2.5 years)
• Parents adopting more than one orphan had much
  more difficulty and stress in parenting

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Behavior Genetics

• Identical Twins
• develop from a single zygote (fertilized egg)
  that splits in two, creating two genetic replicas
• Fraternal Twins
• develop from separate zygotes
• genetically no closer than brothers and sisters,
  but they share the fetal environment

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Behavior Genetics

• Temperament
• a persons characteristic emotional reactivity
  and intensity
• Heritability
• the proportion of variation among individuals
  that we can attribute to genes
• may vary, depending on the range of populations
  and environments studied

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Behavior Genetics

• Interaction
• the effect of one factor (such as environment)
  depends on another factor (such as heredity)
• Molecular Genetics
• the subfield of biology that studies the
  molecular structure and function of genes

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Early Environmental Influence

• Two placental arrangements in identical twins

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Twins (Video Clip)
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Environmental Influence

• Experience affects brain development

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Normal Brain Growth
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Environmental Influence

• A trained brain

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Environmental Influence

• Culture
• the enduring behaviors, ideas, attitudes, and
  traditions shared by a large group of people and
  transmitted from one generation to the next
• Norm
• an understood rule for accepted and expected
  behavior

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Environmental Influence

• Personal Space
• the buffer zone we like to maintain around our
  bodies
• Memes
• self-replicating ideas, fashions, and innovation
  passed from person to person

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The Nature and Nurture of Gender

• X Chromosome
• the sex chromosome found in both men and women
• females have two males have one
• an X chromosome from each parent produces a
  female
• Y Chromosome
• the sex chromosome found only in men
• when paired with an X chromosome from the mother,
  it produces a male child

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The Nature and Nurture of Gender

• Testosterone
• the most important of the male sex hormones
• both males and females have it
• additional testosterone in males stimulates
• growth of male sex organs in the fetus
• development of male sex characteristics during
  puberty

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Testosterone effects

• Dr. Daryl O'Connor (2000), a co-author of the
  study, said "Previous research has shown that
  men outperform women on spatial ability, such as
  map reading, and women outperform men on verbal
  ability. It is a well-known gender difference.
• The fact that higher levels of testosterone
  improved men's verbal fluency was unexpected and
  these findings give us a preliminary insight into
  the non-sexual benefits of the hormone." The
  World Health Organization study was presented at
  the British Psychological Society's annual
  conference in Winchester.

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Role

• a set of expectations (norms) about a social
  position
• defining how those in the position ought to behave

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The Nature and Nurture of Gender

• Gender Role
• a set of expected behaviors for males and females
• Gender Identity
• ones sense of being male or female
• Gender-typing
• the acquisition of a traditional masculine or
  feminine role

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Same Gender relationships

• Deborah Tannen
• He says She says (Video Clip)
• Sexism

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The Nature and Nurture of Gender

• Social Learning Theory
• theory that we learn social behavior by observing
  and imitating and by being rewarded or punished
• Gender Schema Theory
• theory that children learn from their cultures a
  concept of what it means to be male and female
  and that they adjust their behavior accordingly

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Gender Typing
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Families with both parents
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Harris (1998) peer influence

• Dont Blame Your Parents The Nurture Assumption
  on Trial (talk at APA)
• Parents influence on their children is context
  dependent - specific to home.
• The idea that children need constant attention
  and affection until the day they leave for
  college is a product of our culture. an
  unfounded assumption
• Theory of group socialization is that the people
  who had formative influence are not parents by
  the peer group as a whole.

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Addendum Natural and not-so-natural Selection

• Basic idea of natural selection is that only some
  survive to mate and carry forward their genetic
  code
• So selection into the gene pool is from the
  offspring that have offspring
• The simple notion of mating competition has been
  used as a major explanatory approach by
  evolutionary psychologists
• However there are other situations that limit the
  gene pool

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Other Natural Selection mechanisms include

• Miscarriages and spontaneous abortions
• Death during pregnancy of mother or child
• Death in childbirth of mother or child
• (size of head and size of pelvis)
• Fatal childhood diseases
• Accidental death of children (childhood mortality
  rates)

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Not-so-Natural Selection include

• Genocide (as in Ruanda)
• Child and adolescent suicide
• Child Mortality related to child labour
• Child armies (function of lighter guns)
• Selective small family size (Canada and income)
• (China - one child social policy and preference
  for males)
• Selective Abortions (in India 97 of abortions
  are female)
• Adoption Services

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Selective Application of Medicine

• Fertility clinics for the advantaged
• Genetic Screening - Downs Syndrome
• Genetic Screening - aborting females
• Intensive Care for premature babies (100-200k
  per case)
• Genetic therapies

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Selective applications of Science

• Selective Cloning of the Very Wealthy?
• Patenting of mutant genetic code
• Targeted Biological Weapons (selective flu)
• Enhanced training in how to kill via videogames
  for children
• Controlled famines with gene pool consequences
• Implanted identification devices (Digital Angel)