Transcript Biological Bases of Behavior

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Total of 46 chromosomes-threat like
structures made of DNA molecules that
contain genes
› 23 from mom and 23 from dad
› DNA: contains genetic information
› Genes: biochemical units of heredity
› Book example
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Genes can be active or inactive
Environmental events “turn on” genes
› When turned on, they provide the building
blocks of physical development
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Human genome: common human DNA
› Share 96% of our DNA with Chimps
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Most of our traits are influenced by
many genes
› Physical to Intelligence
› https://www.youtube.com/watch?v=ubq4e
u_TDFc
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Identical: develop from a single fertilized
egg that splits in two genetically identical
› Share same genes, but may vary on the
number of copies of those genes
› Some are mirror images of each other: left vs
right hand or have different personalities
Fraternal: develop from separate fertilized
eggs
 https://www.youtube.com/watch?v=Trc2
dJgeyvc
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Read Case Studies page 97-99
 Conclusions based on the reading?
 What do we need to be careful about
regarding separated identical twin
studies?
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They continued to find similarities not only to
taste and physical attributes but also of
personality, abilities, attitudes, interests, and
even fears
Remarkable similarities in life choices,
support the idea that genes influenced
personality
Greater appreciation of genetic influences
Don’t over generalize!
https://www.youtube.com/watch?v=0yTCS
hemS_0
Parents vs. Adoptive Parents
 Hereditary shapes personality
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› Adoptees more similar to biological parents in
personality than adoptive parents
However, parents due influenced their
child’s attitudes, values, manners, faith, and
politics
 Most adoptive children thrive
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› Self-giving parents: children become more self-
giving, score higher on intelligence tests than
biological parents
The extent to which variation among
individuals can be attributed to their
differing genes. Rather it explains that
50% of the observed variation among
people
 Just because a trait is heritable does not
mean it will affect an individual
 We can never say what % of an
individual's personality or intelligence is
inherited
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Individual differences in height and
weight are highly heritable yet nutritional
rather than genetic
 Heritable individual difference need not
imply heritable group differences
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› Ex: Putting people in a new social context
can change their aggressiveness
Environment triggers gene activity
 Genetically influenced traits evoke
significant responses in others
 We select environments suited to our
natures
 Think nature via nurture
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Molecular Genetics: identify specific
genes influencing behavior
 Goal is to find some of the genes that
influenced normal human traits such as
body weight, sexual orientation,
personality, and mechanism that control
gene expression
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Genetics tests can reveal at-risk
populations for many diseases
 Medical personnel are able to provide
parent with a readout on how their fetus
gene’s differ from the normal patter
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› Double-edged sword? Problems?
Discrimination?
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Focus on what makes humans so a like
and use Darwin’s theory on natural
selection to understand the roots of
behavior and mental processes
Darwin
 When certain traits are selected by
reproduction those traits will prevail
 Genes allow us with a great capacity to
learn and adapt to life in varied
environments
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Shared human traits shaped by natural
selection
 Shared human genome
 Outdated tendencies: crave sweets and
fats
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Gender differences in sexuality
 Natural Selection and Mating
preferences
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› Ancestral History: Women more relational,
choosing wisely Men more recreational,
pairing widely
› Today: Women attracted to more mature,
bold, dominant, affluent. Men youthful/fertile
appearance (WHY?)
What’s considered attractive does vary
time and place
 Cultural expectations can bend genders
 Social expectations and mate
preferences
 How we came to need does not dictate
how we ought to be
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