Prior to 1990 there was a huge amount of research looking at biological and biochemical factors in relation to criminal activity, studies by Hippchen (1978) looked at the role of vitamin and mineral deficiencies in criminal behaviour and the effect vitamin B3 deficiency has on children and adolescents, however Weiss (1983) argued that hyperactive children have an increased risk at later delinquency, other such studies have examined dietary factors such as levels of protein, carbohydrates and sugar in relation to criminal behaviour.
Following 1990 there have been a number of studies in the area of biology and it's relation to crime, it has long been argued that physiological under arousal may be a causal determinant of violent and criminal behaviour (Eysenk, 1977, Hare 1970, Quay, 1965) and following several studies into the subject under-arousal by Raine and Liu (1998) it was found that low levels of physiological arousal at an early teenage age influence the chance of criminal activity in later life, other biological factors were also found during the studies, violent adults were found to often have dysfunctions to the prefrontal regions of the brain and it was also found that birth complications and maternal rejection at age one influenced the chance of violent crime at age eighteen. The theory is supported by Miller et al. (1997) in this study the presence of antisocial conduct was compared in a random sample of 22 patients with frontal lobe damage versus 22 participants with no known damage, results showed that 10 patients with frontal lobe damage showed antisocial behaviours compared to only 1 participant with no damage, this difference was highly significant (P = 0. 004).
The study supports a relationship between frontal-temporal dysfunction and certain types of antisocial activities. Another study carried out by Bennett et al. (2001) also supports the view that pre-frontal lobe deficits cause violence and crime, pointing out that there is much less crime committed by females than males due to females having fewer frontal lobe deficits than males, females also acquire social cognitive skills earlier in life than males and have better pro-social skills, these superior social cognitive skills are influenced by many factors, including better interhemispheric communication and fewer frontal lobe deficits.
An example of a study that further explains gender differences associated with crime was carried out by Dabbs et al. (1995) the study concerns the endocrine system which consists of the regulation of hormones and has been linked to the practice of violent crime, these hormones include testosterone progesterone and insulin, these hormones exert a strong influence on behaviour, testosterone is the most prominent of all hormones that is related to criminal behaviour, Dabbs et al. study was carried out over five years on 692 prison inmates to find how testosterone related to crime and behaviour , they found that higher levels of testosterone were related to crimes such as rape, homicide and assault and that lower levels of testosterone were associated with crimes such as burglary and theft, they also found that within the prisons inmates with high testosterone levels behaved more dominantly and frequently got into more trouble, inmates with lower levels were said to act more sneaky and treacherous .
Dabbs & Hargrove (1997) studied 87 female inmates in a maximum security prison aged 17 to 60 and found a direct link between testosterone levels and aggressive behaviour, they also found that as age increased aggression decreased, and that behaviour of inmates with different levels of testosterone was similar to the males. One major criticism to the likes of Dabbs et al. study, which has been pointed out by researchers including Raine and Liu (1990) is that such studies only look at institutionalised populations within there data, ignoring the wider picture and the overall cause of criminal behaviour. Research by (Soler, Vinayak & Quadagno 2000). Into aggressive child's play has found a significant correlation with high testosterone in boys, Sanchez (2000. )
Bernharet (1997) suggests that testosterone doesn't act alone in creating aggression; it is this combined with low levels of the brain chemical serotonin that creates aggression. Overall this research shows high testosterone levels to create 'dominance seeking behaviour' which was also found in businessmen and successful athletes as well as criminals, this indicates that other influences coupled with high testosterone influences the outcome of becoming a violent offender. Booth and Osgood (1993) believe that high testosterone is an indirect cause of crime, as aggressive behaviour in children may alienate other children and therefore create fewer social bonds and thus lead to the isolation of a criminal career.
In addition the higher concentration of testosterone in convicted inmates could be attributed to social factors and previous life experiences. One other theory from the biological view is Physiological theory, this is the identification of the psychopathic personality (Senna & Siegel, 1990). Psychopathic personality is caused by physical abnormality in the autonomic nervous system (ANS). The ANS mediates internal activities such as heart beat and blood pressure when associated with emotions. The physical abnormality can be caused by genetic and biochemical factors. Therefore, psychopathic personality is predisposed innately and is unaffected by socialization.
Psychopath experiences lower arousal levels to stimuli and react differently from the normal. Therefore, it is possible that psychopaths are thrill seekers who engage in high-risk, antisocial activities to raise their general neurological level to a more optimal rate (Senna & Siegel, 1990). Criminals are potential psychopaths who devoted in risky activities. There is much evidence suggesting that biology has a major part to play in the development of aggressive and criminal behaviour, yet this cannot be put down as the sole reason, a major argument against this view is the argument for freewill and determinism, a argument that stems back hundreds of years to classical theorists such as Cesare Beccaria and Jeremy Bentham.
The central points of this theory are, The human being is a rational actor, it also looks at people freely choosing all their behaviour based on their rational calculations, The central element of calculation involves a cost benefit analysis: Pleasure versus Pain, Choice, with all other conditions equal, will be directed towards the maximization of individual pleasure, Choice can be controlled through the perception and understanding of the potential pain or punishment that will follow an act judged to be in violation of the social good, however there does not seem to be much evidence of this view since 1990 and positivist research on social, psychological, and biological causes of crime focused attention on the factors that impose upon and constrain the rational choice of individuals.
According to a paper published by Cornish and Clarke (1990) free will is assumed, but there are certain background and situational factors that might predispose someone toward crime. Background factors would include psychological characteristics, like how intelligent the person is; social factors like family background; and demographic factors, like what kind of neighbourhood the criminal comes from, however the theory does not go into detail about the biological factors. In a paper by Mitchell (2002) titled "The intoxicated offender-Refuting the legal and medical myths" which looks at the role of freewill and determinism in criminal behaviour, it is said that every person makes a decision about what is right and what is wrong and biology cannot be the determent in such a decision.