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Biological Determinants of
Aggression
Overview of Biology/Physiology
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Evolution (we already talked about)
Genetic
Neurotransmitters
Hormonal
Structural
Biology/Physiology is probabilistic, not
deterministic (so how to prevent aggression?)
Genetics
• Behavioral genetic research has shown genes influences individual
differences in a wide range of human behaviors: cognition,
academic achievement, personality, temperament, and so forth.
• What about aggression?
• How studied?
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Heritability
Environmental
Monozygotic twins
Dizygotic twins
Adoption studies
Adoptive siblings
Biological siblings
• Findings
• Clear evidence of
• Mixed results of
• Possible indirect effect through
Genetics
• A chromosome is an organized structure of DNA
and protein that is found in cells.
• Men – XY
• Women – XX
• Y-Chromosome Hypothesis
• XYY
• X-Chromosome Hypothesis
• XXY
Only have to know first line for Final
Neurotransmitters
• Dopamine
• Norepinephrine
• Serotonin
• GABA
Hormonal
• Testosterone
• sex hormone and anabolic steroid that has
mixed evidence to producing aggression,
more likely about status and dominance so
indirect relationship to aggression
• Premenstrual Syndrome (PMS)
• inconclusive evidence its associated with
aggression and criminality but see next
slide for indirect relationship
Structural
• Hypothalamus – located under the thalamus that
controls several body functions, including feeding,
breathing, drinking, and temperature.
• Amygdala – an almond-shaped neural structure that
regulates emotions.
• Prefrontal cortex – implicated in planning complex
cognitive behaviors
• How to study?
• Brain damage
• Direct stimulation
• Physiological
Reactivity