Biological

• Physiological theories


  Biological theories that claim the physical features of criminals differ from those of non-criminals
• Lombroso's theory


  'Born criminals' - Criminals are physically different from non-criminals
• Lombroso's research


  1. Measuring and recording details of the heads and faces of thousands of prisoners

  2. Concluding that criminals could be identified by distinctive physical features
• Distinctive physical features of criminals


  • Enormous jaws
  • High cheek bones
  • Handle-shaped ears
  • Prominent eyebrow arches
  • Exceptionally long arms
  • Large eye sockets
  • Extremely acute eyesight
• Atavism


  Criminals as throwbacks to an earlier, primitive stage of evolution
• Lombroso saw criminals as pre-social, unable to control their impulses, and having reduced sensitivity to pain</b>
• Lombroso identified 'born criminals', 'moral criminals', and 'epileptic criminals'
• Sheldon's somatotypes theory


  Certain body types or 'somatotypes' are linked to criminal behaviour
• Sheldon argued that mesomorphs are the somatotype most likely to engage in crime
• Genetic theories


  Criminality is inborn and passed down from parent to child
• Studies showing crime runs in families

  • Cambridge Study in Delinquent Development
  • Osborn and West study
• Twin studies


  Comparing identical (MZ) and non-identical (DZ) twins to test for genetic causes of criminality
• Christiansen's study found a 52% concordance rate for criminality between identical twins, compared to 22% for non-identical twins
• Adoption studies


  Comparing adopted children's criminality to their biological and adoptive parents to test for genetic causes
• Mednick et al found adopted sons were more likely to have a criminal record if a birth parent also had one
• XYY syndrome


  Abnormality of the sex chromosomes that has been linked to aggression and violence in men
• Studies have found a higher than average proportion of inmates in secure psychiatric hospitals have XYY syndrome
• Brain injuries


  Certain dysfunctions and malfunctions of the brain have been linked to criminal behaviour
• Brain injuries


  • The case of the railway worker Phineas Gage, whose personality changed after a major brain injury
• There are some cases of brain injuries being identified as the cause of criminality
• Prisoners are more likely than non-prisoners to have suffered a brain injury
• Brain diseases


  Some brain diseases have been linked with criminal or anti-social behaviour, such as impulsiveness, arson and abnormal sexual behaviour
• Brain diseases


  • Senile dementia, Huntington's disease and brain tumours have also been linked to various forms of deviant or anti-social behaviour
• In the 1920s, epidemics of encephalitis lethargica among children were linked to destructiveness and deviant or anti-social behaviour
• Abnormal brainwave activity


  Brainwave activity is measured by an electroencephalograph (EEG), and some studies show abnormal EEG readings among 'clearly insane murderers and psychopathic criminals'
• Biochemical explanations


  Biochemical substances and processes have been suggested as possible causes of criminal behaviour, because of their effect on brain chemistry and mental processes
• Biochemical factors linked to criminal behaviour

  • Sex hormones
  • Blood sugar levels
  • Substance abuse
• Sex hormones


  Overproduction or underproduction of hormones may cause emotional disturbances and lead to criminal behaviour
• Males of most species are more aggressive than females, and the male sex hormone testosterone has been linked with crimes such as murder and rape
• Testosterone levels peak from puberty to the early 20s and this age range coincides with the highest crime rates in males
• Females


  Pre-menstrual tension (PMT), post-natal depression and lactation (breastfeeding) have all been accepted as partial defences for women charged with crimes ranging from shoplifting to infanticide, on the grounds that the hormones involved have affected the defendants' judgment, mood or self-control
• Blood sugar levels


  Hypoglycaemia (low blood sugar) can trigger aggressive reactions, and studies show a link between low blood sugar and alcohol abuse
• Drinking large quantities of alcohol can induce hypoglycaemia and increase aggression, and alcohol consumption is closely linked to crimes of violence
• Schoenthaler claims that by lowering the daily sucrose intake of young offenders, he could reduce the level of their anti-social behaviour
• Substance abuse


  The intake of drugs and other substances, both legal (e.g. alcohol and glues) or medically prescribed (e.g. barbiturates), and illegal (e.g. cannabis, MDMA, LSD, heroin and cocaine)
• Alcohol played a significant role in about 1,000 arrests per day, and in the USA, 80% of family violence cases involved alcohol
• Cocaine and 'crack' are closely linked with violence, whereas cannabis, heroin and MDMA tend to reduce aggression
• Other substances linked to anti-social or criminal behaviour

  • Food additives and diet
  • Allergens
  • Vitamin deficiencies
  • Lead pollution
• Both lead and the synthetic food colouring tartrazine have been linked with hyperactivity, and vitamin B deficiency has been linked to erratic and aggressive behaviour
• The link between such substances and criminality is not always clear