Biology

Background/Aim: Raine, well known for his murderers' brains study has conducted an extensive review of research to identify.

Sample: Varied, not geographically specific, wide variety of age ranges.

Method: Review of research articles on biological bases of anti-social and aggressive behaviour in children. Cross- sectional and longitudinal studies, many ruling out a wide range of potentially confounding variables (e.g. low IQ, poor academic ability, etc.) Selective focus on low autonomic functioning, prefrontal deficits and early health factors.

Results: A low resting heart rate is identified as a predictor of someone who is fearless/ seeks stimualation and excitement. Structural and functional deficits found in pre-frontal lobe (brain), e.g. reduced blood flow and reduced glucose, are related to anti-social and aggressive behaviour often characterised by a lack of inhibitory control (from neuropsychological, neurological and brain-imaging studies). Birth complications (e.g. lack of oxygen, forceps delivery and pre-eclampsia) are selectively associated with later violent behaviour (interaction with maternal rejection). Significant link between smoking during pregnancy and later conduct disorder/violent offending. Deficiencies in nutrition (findings somewhat controversial) but aggression and anti-social behaviour have been associated with food additives and deficiencies in iron, vitamins and protein.

Evaluation: Can infer a respectable researcher would identify an appropriate range of published research articles which have scientific standing (thererfore fairly reliable); however, cannot eliminate the possibility of researcher bias in the review process. Variation in sample sizes means relaibility could be questioned, but many studies replicated and 'elimination' if confunding variables results in greater reliability. There is a danger of offering only biological deterministic and reductionist explanantions of offending behaviour. Research suggests that early health intervention can potentially reduce later problems. Predictors which allow early identification must be useful; however, the danger is labelling someone as violent/aggressive, leading to 'self-fulfilling prophecy'.

Background: An early study seemed to offer that genetic abnormality was strongly implicated in violent crime ( the XYY syndrome); however, Witkin's later Danish study discounted this explanation and drew attention to lower interlligence as a more important factor (infer link to low school attainment).

Aim: To investigate genetic abnormality and violent behaviour.

Sample: 5 males from a Netherlands family ( with syndrome of X-linked borderline mental retardation and abnormal violent behaviour); only one completed regular primary education (+detailed case histories of three more affected males).

Method: Blood samples (to isolate DNA) and analysis of urine samples over 24hours (and some 'clinical' case study behavioural material reported by family).

Results: Tests revealed a point mutuation in the X chromosome of the gene responsible for production of monoamine oxidase A (MAOA - involved in serotonin metabolism). Males showed disturbed aggression regulation. Aggressive behaviour usually triggered by anger (usually out of proportion to provocation).Other abnormal behaviour documented: ****/attempted ****, stabbing, arson, exhibitionism and voyeurism.

Evaluation: the very small sample is unreliable and as not all males in this family were affected by associated violent behaviour the findings cannot be generalised, nor can they be considered very useful. This research can be used to illustrate the weaknesses of using biologically deterministic and reductionist explanations of criminal behaviour.

Background: Evolutionary explanations of criminal behaviour argue that 'more risky' and/or aggressive behaviour in males can be understood in terms of competition for mates, food and ultimately survival. Impulsiveness and risk-taking have been identified in research already and this study investigates thet relationship between life expectancy and homicide rates. 'Risk- taking' is seen as a characteristic of male behaviour and is most likely to occur in a social context of peers.

Sample: From 77 relatively stable community areas, chicago.

Method: A correlation study investigating the relationships between a)life expectancy and homicide rates and b) life expectancy and income inequality usuing the demographic data from illinois Department of Public Health, police records and population census data 1990.

Results: Strong negative correlations (p < 0.0001) a) -0.88 and b) -0.75. Homicide rates per 100,000 (across 77 areas in Chicago) ranged from 1.3 to 156 and life expectancy ranged from 54-77 years old. a) Authors questions whether young men expecting to live shorter lives (high homicide rate neighbourhoods) engaged in more risky behaviour to gain (short-term) rewards; b) Poverty can be understood as a motivating factor in offending.

Evaluation: Correlations don't allow the establishment of cause and effect. The (inferred) large sample is reliable and the variety of data from census, police and school records is not liable to subjective interpretation and therefore valid and also reliable. (Biological) determinism and nature. Both the research and the explanations offered are reductionist, as a range of social or cognitive factors likely to be involved in offending are not considered. Nurture: young men seeing relatives/friends die young. Freud and Ethological theory consider aggression as innate (nature debate).