Theories of Crime Biology

Lombroso Lombroso in 1876 argued that the criminal is a separate species, a species that is between modern and primitive humans. He argued that the physical shape of the head and face determined the "born criminal".

Lombroso

                                                 

William Sheldon believed that people could be classified into three body shapes, which correspond with three different personality types. endomorphic (fat and soft) tend to be sociable and relaxed. ectomorphic (thin and fragile) are introverted and restrained mesomorphic (muscular and hard) tend to be aggressive and adventurous. Sheldon, using a correlational study, found that many convicts were mesomorphic, and they were least likely to be ectomorphic (Sheldon et al 1949).

Sheldon

Genetic - XYY Normal Male

Genetic - XYY Jacobs et al (1965) suggested that men with the XYY syndrome were more aggressive than normal 'XY' men. XYY men are over-represented in the prison population. There are 15 sufferers per 1,000 in prisons and 1 per 1000 in the general population. XYY Male

Neurophysiological Raine 1994 used PET scans to study the living brains of impulsive killers. Damage was found in the pre-frontal cortex, which controls impulsive behaviour. The task used involved sustained attention. It involved watching a screen for 32 minutes and responding every time a 0 appeared. Impulsive individuals also missed many of the 0s. Oddly enough, pre-frontal under arousal has also been found in politicians!  

Neurochemical The brain’s chemistry can be influenced by diet, for example, food additives, pollution or hypoglycaemia (low blood sugar levels associated with forms of diabetes). Dawn Stanton attacked her husband with a knife when hypoglycaemic. But not all diabetics without insulin act criminally.

Neurochemical Individuals who take large amounts of steroids can become extremely violent (known as "roid rage"). Steroids, usually taken to increase muscle growth, also increase testosterone levels. Horace Williams, a body builder, beat a man to death after taking two thousand times the recommended dosage of steroids.

Monozygotic twins

Twin studies An 'MZ apart' study is when two monozygotic children have been brought up apart. If both turn out to be criminals then this would be support for the genetic explanation. The degree of similarity between two twins is known as the concordance rate. This rate can then be compared with dizygotic twins who are brought up together ('DZ together'). Looking at a number of studies the average concordance rate is 55% for MZ twins and 17% for DZ twins (Bartol, 1999).

adoption studies No 13.5 Yes 20.0 12 14.7 7 24.5 40 3 Biological parents have criminal record Adoptive parents have criminal record % of sons with criminal record (Mednick 1987) % of sons with criminal record (Bohman, 1995) No 13.5 3 Yes 20.0 12 14.7 7 24.5 40