Neural and Hormonal Aggression

Neural and Hormonal Aggression

1. Brain Chemicals

   • Low levels of serotonin associated with increased susceptablilty to impulsive and aggressive behaviour
   • Serotonin usually prevents stimulation of the amygdala so if there are low levels, amygdala more active
     • More likely to be aggressive and act on impulsives
   • Case study of Charles Whitman who went on sporadic killing spree then killed himself - wrote a suicide note asking for an autopsy as he knew something was wrong with him
     • Autopsy showed tumor pressing against his amygdala possibly triggering his actions

2. Evidence of serotonin

   • The use of drugs that raise serotonin levels in the brain i.e. antidepressants
   • In clinical studies, antidepressants drugs which elevate serotonin levels also tend to reduce irritability and impulsive aggression
   • Suggests increased serotonin levels do lead to reduced aggression but this relationship may not be casual
   • Non-human animals - Popova et al found that among dogs selectively bred for domestication and for increasingly docile temperament, there has been a corresponding increase of brain serotonin
     • Suggests a link between low levels of serotonin and aggression
     • Extrapolation is an issue - different brain structures to dogs

3. Challenge to serotonin argument

   • Meta-analysis of studies that had examined neurotransmitters levels in anti-social children and adults
   • Found lower levels in those individuals described as aggressive

4. Testosterone

   • Is a form of an androgen which is made daily in the male testes. It is thought to increase levels of aggression from young adulthood onwards
   • Thought 'T' may influence areas of the brain that control behavioural reactions i.e amygdala and hypothalamous
   • Also influences the levels of other hormones which are thought to be involved in aggression
   • Pillay's Sport Study - testosterone levels varied according to which sport different athletes played. Found male and females who participated in most aggressive sports (boxing) had highest levels of testosterone
   • Klinesmith et al - found when participants assembled a gun, testosterone levels increased + more aggressive toward other participants
     • Real life implication - debating whether gun ownership should be allowed (USA)

5. Basal Model

   • States levels of testosterone influences dominance
   • The more testosterone someone produces, the more competitive and hence more dominant they become - dominance is the effect of testosterone

6. Critical evaluation

   • Reductionist - complexity of human behaviour means that biological explanations are insufficient on their own to explain the many different aspects of human aggression
   • Research by Bandura et al found social learningcan be a powerful influence on the aggressive behaviour of children

7. Cultural evaluation

   • There must be other social factors that play a part for creating and bringing on aggression in humans due to examples of !Kung tribe who are extremely peaceful and live in a culture with hardly any aggression at all
     • Yanomami tribe are extremely aggressive
   • Would suggest there is something in the culture causing the lack or extra amount of aggression