Biological explanations for offending behaviour
Atavistic form is a historical approach to explaining offending behaviour that saw criminals as having distinguishing physical features, such as a heavy brow and large ears. These were seen as reflecting an earlier, primitive state of development. The genetic explanation, although not arguing for a single ’criminal’ gene, believes that criminality does have an inherited component to it, which is supported by research evidence from twin, family and adoption studies. It is probable that several genes are involved, with criminality more likely when an individual has more of these genes. The neural explanation sees offending behaviour as related to biochemistry, with high levels of noradrenaline (associated with aggression) and dopamine (associated with pleasure) related to criminal behaviour, and low levels of serotonin (associated with impulsive behaviour). The brain physiology explanation argues that specific brain areas are involved with offending behaviour. The limbic system, where emotion is regulated, is especially linked, as criminals often feel little remorse or guilt about their offending behaviour. Research also suggests that low activity in the frontal lobes is associated with not having a conscience, which means that such people would have less restrictions on committing criminal offences.
Fig 16.2 Atavistic features identified by Lombroso (1876)
Farrington (1996) assessed the development of delinquency. 411 males living in London from nearly 400 families were monitored from age 8 to 32 through interviews, and from age 10 to 40 in crime records. Conviction rates of these men were compared to convictions of close family members. They found:
• 64 per cent of the families contained at least one convicted person
• 6 per cent of the families accounted for 50 per cent of all convictions
• convictions of one family member were strongly related to convictions of every other family member
• about 75 per cent of convicted fathers and convicted mothers had a convicted child
• approximately 75 per cent of families containing convicted daughters also contained convicted sons
• convictions of older siblings were more strongly related to convictions of the males than were convictions of younger siblings.
The conclusion was that offending is strongly concentrated in families, suggesting a genetic link.
• Hooton (1939) conducted a 12-year study comparing 13,873 male prisoners in 10 US states with a control group of 3,023 men to assess physical differences. He found criminals tended to possess a greater degree of sloping foreheads, protruding ears and narrow jaws, supporting the atavistic form explanation.
• Brunner (1993) examined the effects of the MAOA gene, which alters the levels of neurotransmitters of individuals with the shortened version of the gene. A link was found to heightened aggressive behaviour, which suggests a genetic and biochemical link to violent crime.
• Raine et al. (1997) assessed whether there were differences in brain activity of murderers and non-murderers. 41 violent murderers’ brains were investigated using a PET scanner. Differences were found in activity in brain areas linked to aggression, such as the prefrontal cortex and the limbic system, which suggests brain physiology may be involved in murder.
It may be that the atavistic form explanation has some validity, but not because it reflects a primitive state of development, but because people with ’ugly’ characteristics may be treated in a negative way by society, have less access to employment and so are likelier to indulge in criminal behaviour.
Research from twin studies suggests a genetic link to offending behaviour, as concordance rates for criminal behaviour is higher in MZ twins (who are 100 per cent genetically similar) than DZ twins (who are only 50 per cent genetically similar).
If offending behaviour has a biological basis, then it has been argued that offenders are not responsible for their actions and so should be treated more humanely.
Although family studies show that criminal behaviour runs in families, suggesting a genetic explanation, such behaviour could equally be due to social learning or other environmental influences. Equally offending behaviour in individuals who were adopted may be due to the stress of adoption rather than genetics.
Much research into biochemistry and criminality has been conducted on animals and so raises issues of extrapolation. Higher levels of aggression in mice with abnormal biochemistry does not necessarily explain human violent crimes.
Sample sizes for studies of brain abnormalities and criminality are often very small, therefore throwing doubts over the extent to which they can be generalised to the general population.
The main practical application of research into biological explanations of offending behaviour is in the development of treatments to lower the incidence of such behaviour. For example, the manufacture of drugs that regulate neurotransmitter activity in those demonstrating criminality.