Biological explanations of CB (Genetic + neural explanations) Flashcards
What are the main assumptions of the genetic explanations of CB?
- Offenders inherit a gene or combination of genes that predisposes them to commit crime.
Brunner’s discovery
- Brunner discovered a genetic defect in male members of a large abnormally violent Dutch family.
- Non-violent male members within the family did not carry this genetic mutation.
What specific gene did Brunner find?
- Brunner found that a faulty, low activity version of the MAOA gene was common in all violent men in the family.
- This gene has now been established as a key biological factor in impulsive aggression and as a prominent genetic cause of criminal violence.
What is the low activity variant of the MAOA gene known as?
- ‘Warrior gene’.
What does the MAOA gene code for?
The MAOA gene codes for the MAOA enzyme.
- This enzyme breaks down serotonin, so men with the mutant low activity gene do not produce enough MAOA needed to regulate serotonin levels, this causes them to have abnormally high serotonin activity.
What do high levels or serotonin contribute to?
- Emotional sensitivity.
- Impulsivity.
- Mood dysregulation under stress.
What does research suggest about MAOA-L individuals?
- Research suggests that MAOA-L individuals are hypersensitive, so are affected more by negative experiences so they react more aggressively in defence than others.
What is the relationship between MAOA and violence?
- There is strong evidence that the MAOA predisposes men to violence and crime; evidence for the interaction of this gene with the environment has been found; MAOA-L individuals display significantly higher levels of aggression in a high provocation situation, but there is little/ no difference in aggression in low provocation situations.
Warrior gene (more info)
- About 30% of men have this warrior gene, but whether the gene is triggered or not depends crucially on what happens in childhood.
- A longitudinal study on children found that those with the MAOA-L genotype paired with maltreatment in childhood were correctly predicted to commit crime.
Neural explanations (the criminal brain) RAINE
- Raine was the first person to conduct a brain imaging study on murderers and has since scanned the brains of many violent criminals, looking for similarities.
What similarities did Raine’s study find?
Raine’s brain scanning studies found two similarities in the brains of nearly all his participants:
1) Reduced activity in the pre-frontal cortex, which means less emotional impulse control.
2) Over activation of the part of the brain that controls our emotions, the amygdala.
What does Raine’s study suggest?
- Raine’s study suggests that murderers have brains that make them prone to rage and anger, while at the same time making them less able to control themselves.
What ethical implications does Raine’s study have?
- The findings from these studies highlights an ethical dilemma.
- Since individuals cannot be held accountable for their genes or their brain function, should they be held responsible for their dispositions and resulting actions?
Evaluation of biological explanations (C&E)
- There is convincing evidence to support a biological basis to offending, but cause and effect cannot be established in any human studies- these all rely on correlation and so other variables could be responsible for the offending behaviour.
- Experimental animal studies have been conducted in an attempt to establish causation.
Evaluation of the biological explanations (animal studies)
- In one study the MAOA gene was disabled on the X chromosome in mice and this caused heightened aggression particularly in response to perceived threats or provocation.
- This supports the idea that low MAOA activity disrupts normal regulation of aggression and could in fact cause violent offending.
- Another issue is that altered biological function may be a consequence of offending behaviour rather than a cause.
Other neural explanations (Noradrenaline)
- Noradrenaline is part of the fight or flight response and helps respond in a threatening situation. There is research to suggest that high levels are linked to violence and aggression and so, as a consequence, it is easy to explain some crimes as possibly being underpinned by the chemical imbalance.
Other neural explanations (dopamine)
- Dopamine is implicated in offending behaviour because of it’s link to addiction and therefore substance abuse. This makes crime more likely. Dopaminergic activity in the limbic system means that pleasure is experienced, and the greater the activity, the greater the feeling of pleasure. This makes addiction more likely.
Neural explanation (Research=Higley)
- Higley et al found that levels of testosterone were positively correlated with aggressiveness but not impulsivity, whereas levels of serotonin were negatively correlated with impulsive behaviour and extreme aggression, but not general aggression. This work was done on male non-human primates,
- These results seem to suggest how biochemical levels may underpin offender behaviour.
