Sheldon's Somatotypes Theory

William Sheldon proposed a theory linking body types (somatotypes) to personality traits and criminal behavior. After studying 4,000 men, Sheldon identified three main somatotypes:

1. Ectomorphic: Lean, poorly muscled individuals with introverted and sensitive personalities.
2. Endomorphic: Plump, fat individuals with sociable and relaxed personalities.
3. Mesomorphic: Muscular individuals with assertive and dominant personalities.

Definition: Somatotype - A body type classification system based on the relative contribution of three extreme body types.

Sheldon conducted a correlation study of 200 boys and found that mesomorphic boys were disproportionately prone to delinquency. He concluded that a tough body is necessary for survival on the streets and that mesomorphs are more likely to engage in risk-taking behavior.

Highlight: The somatotype theory in criminology suggests that physical build may influence criminal tendencies, with mesomorphic individuals being more prone to delinquent behavior.

Genetic Theories of Criminality

Genetic theories explore the potential role of chromosomal abnormalities and heritability in criminal behavior.

XYY Syndrome (Jacobs' Study)

Patricia Jacobs proposed that criminality could be linked to genetic makeup, specifically chromosomal abnormalities. The XYY syndrome, also known as Jacobs syndrome, was believed to be associated with increased aggression and potential violence.

Vocabulary: XYY syndrome - A rare chromosomal disorder in males characterized by an extra Y chromosome.

Jacobs' study found that 15 in 1,000 men in prison had XYY syndrome, compared to 1 in 1,000 in the general population. This suggested a potential genetic explanation for criminal behavior.

Example: John Wayne Gacy, responsible for sexually assaulting and killing 33 men in the USA, is said to have had XYY syndrome.

Twin Studies

Christiansen (1977) conducted twin studies to investigate the heritability of criminal behavior. The study compared concordance rates between monozygotic (MZ) and dizygotic (DZ) twins.

Definition: Concordance rate - The likelihood that a pair of twins will share a specific trait or characteristic.

Results showed higher concordance rates for criminal behavior in MZ twins compared to DZ twins, suggesting a genetic component to criminality.

Adoption Studies

Adoption studies aimed to separate genetic and environmental influences on criminal behavior by comparing adopted children with their biological and adoptive parents.

Hutchings and Mednick (1975) studied 14,000 adopted children and found a high proportion of boys with criminal convictions had biological parents with criminal convictions, suggesting a genetic link to aggression.

Highlight: Mednick (1994) found no relationship between adoptive parents' criminal convictions and their adopted children's convictions, but did find a significant correlation between biological parents' convictions and their offspring's criminal behavior.

These studies provide evidence for both genetic and environmental influences on criminal behavior, highlighting the complex interplay between nature and nurture in shaping criminal tendencies.

Lombroso's Theory of Criminal Anthropology

Cesare Lombroso developed a theory of criminal anthropology based on Charles Darwin's work. The Lombroso theory proposed that criminals were a separate species with distinct physical features indicating atavism or primitive traits.

Lombroso conducted a study examining the facial and cranial features of over 4,000 criminals. He concluded that 40% of criminal acts could be attributed to atavistic characteristics. The Lombroso theory features included physical traits like a flattened nose, large jaw, tattoos, large ears, and a sloped forehead.

Example: According to Lombroso, a murderer might have curly hair and bloodshot eyes, while a sex offender could have thick lips and protruding ears.

Highlight: A recent Chinese study used AI software to identify criminals based on physical features, with only a 6% error rate.

Lombroso also described other aspects of criminality, such as the use of criminal slang and insensitivity to pain. He believed that female criminals, particularly prostitutes, had distinct physical characteristics as well.

Vocabulary: Atavism - The reappearance of primitive traits in modern organisms.