Biological Theories of Crime

Biological and Psychological Theories of Crime

Biological and psychological theories of crime explore offending behaviour from different perspectives. Psychological theories focus more so on personality factors, psychodynamic explanations, and learning explanations. Biological explanations explore biological aspects of crime, such as Lombroso's atavistic form, genetic explanations, and neurological explanations.

Biological Theory of Crime: Definition

Biological theories of crime assume a person’s biological characteristics predetermine criminal behaviours. The theories that discuss the origin of crime and the influences on a person’s decision to commit a crime include classical, biological, sociological, interactionist and psychodynamic approaches.

Biological theories of crime focus more on the biological factors influencing a person's behaviours.

Are their genes the cause of their delinquency? Can we spot criminals based on physical features? Various theories explore the biological aspects of criminal behaviour.

Biological Theory of Crime: Examples

Biological theories of crime focus on two key theories, as well as exploring certain types of studies to identify where the environment or a person's biology influenced their behaviours more. Biological theories of crime examples include:

• Lombroso's atavistic form.
• Sheldon's Somatypes.
• Adoption and twin studies.

Lombroso's Atavistic Form

One of the oldest biological explanations for crime is the atavistic form. In 1876, Cesare Lombroso proposed that criminals are primitive and genetically different from law-abiding citizens. Not only that, but they also look different compared to normal citizens.

According to Lombroso, criminals have the characteristics:

• High cheekbones
• Facial asymmetry
• A narrow, sloping brow
• A strong, prominent jaw
• Drooping eyelids
• Large ears
• Dark skin
• Extra toes

He also suggested these features are more pronounced in different types of criminals.

Fig. 2 - Lombroso believed criminals had different characteristics¹.

Sheldon's Somatotype

William Sheldon was an American psychologist and physician who, in the 1940s, developed the theory that different body types, or somatotypes, are associated with different personality types, also known as constitutional psychology.

Sheldon proposed that there are three somatypes: ectomorphic, mesomorphic, and endomorphic.

• Ectomorphic: People who are very skinny and tall, with fine bones and statures.
• Mesophormic: People with a strong, square, muscular body type. They have even weight distribution, a good posture and a narrow waist.
• Endomorphic: People who are rounded and soft, overweight and typically short. They have a hard time losing weight.

Sheldon wrote a book about these somatypes and their respective constitutions or personality types called Atlas of Men². His book categorised a range of body types on a scale of 1-7.

• He proposed that pure ectomorphs have a body type of 1–1–7, pure mesomorphs have a body type of 1–7–1 and pure endomorphs have a body type of 7–1–1.

Fig. 3 - Sheldon proposed three body types in Sheldon's Somatotypes³.

The personality types that Sheldon proposed for the three somatypes are as follows:

Genetic and Neural Explanations of Offending Behaviour

More recently, psychologists have identified genes that they believe make a person prone to crime. A genetic predisposition to crime increases the likelihood of offending behaviour, which is often coupled with environmental factors, increasing the chances of a person developing into a criminal.

Scientists have identified several genes they believe may be involved:

• The MAOA gene (the warrior gene, involved in encoding an enzyme that breaks down dopamine and serotonin and has been linked to aggressive behaviour).
• CDH13 (linked to substance abuse and attention deficit disorder).

Psychologists also cite differences in brain function as an explanation for criminal behaviour.

• Specifically, criminals have decreased activity in the prefrontal cortex, an area of the brain involved in regulating emotions. They also have difficulty empathising with others. Unlike neurotypical people, criminals with antisocial personality disorder cannot naturally empathise with others, but they can when prompted.

Biological Theories of Crime: Adoption and Twin Studies

One of the best ways to study the effects of genes on a person’s behaviour is to analyse monozygotic (MZ) and dizygotic (DZ) twins. MZ twins share 100% of their DNA.

Adoption studies are also a great source of information because they show the influence of biological and psychological explanations on behaviour. We can essentially ask if the parents are to blame or if the environment or a person’s genes are at play.

Biological Theory of Crime: Strengths and Weaknesses

Multiple theories explore the biological theory of crime, but are they robust? We must assess their strengths and weaknesses before accepting their theories.

Strengths of the Biological Theories of Crime

When Lombroso first highlighted the role of the physical characteristics of crime, he lent scientific credibility to the role of biology in criminology. Using empirical evidence, he identified a scientific area of criminology that could be further investigated.

Research supports the genetic theory established by Mednick et al. (1984).

• One great strength of adoption studies is that it helps us identify and rule out the environment as an influence, which some twin studies cannot.
• Studies have also linked the genetic origins of aggression and the genetic basis to crime, suggesting it can lead to offending behaviours, further supporting the links.

Like the research on the genetic role in offending behaviour, research supports neural connections theory, as seen in Raine et al. (1997) in their study on brain abnormalities in murderers, increasing the scientific credibility of the theories. Overall, biological theories of crime show strengths in that:

• The studies cited often provide clear proof of some correlation or connection between biological factors and offending behaviours.
• Overall, biological theories are observable and measurable, which increases the scientific credibility of the research on the topic.

Weaknesses of the Biological Theories of Crime

Lombroso highlighted these features as common in criminal subjects. However, he did not compare them to a non-criminal control group, so he cannot confidently say these features are inherent only in criminals. He also ignored other factors that may have affected these physical traits, such as the presence of psychological or mental disorders that present physically in participants.

When using genetic studies, especially in twins, the concordance rate of criminal behaviour should be 100% if criminal behaviour was purely genetic, yet this isn’t the case. This outright shows biological factors are not the only factor in offending behaviours and crime.

These low rates indicate that biological factors are less important than we may suspect and environmental factors are more important than we first thought.

In regards to biological theories of crime overall:

• Biological explanations suffer from being reductionist in that they ascribe complex behaviours to simple biological functions and structures. They are also deterministic.
• Research into this field’s implications on how our judicial and punishment system works requires a sensitive approach to this subject area, as ethical issues can arise from statements such as all criminals have a prominent brow bone, as we have discussed above.
• It also questions whether we can truly punish someone for their behaviour if they are biologically predetermined to commit crimes.