Criminal behavior has complex origins.
While social and psychological factors play a clear role, a growing body of research suggests biological factors also influence criminality.
Here’s what the science says so far about the biology underlying criminal behavior.
Key Facts:
- Genetics account for 40-60% of variance in antisocial behavior. Environmental factors also play a role.
- Three main biological correlates of criminal behavior: psychophysiology, brain structure/function, and genetics.
- Blunted physiological arousal is linked to fearlessness and reduced deterrence from crime.
- Structural and functional impairments found in criminal brains suggest issues with emotion regulation, decision-making, and morality.
- Gene-environment interactions can increase risk, and epigenetics allow life experiences to become biologically embedded.
Source: Psychol Crime Law
How Physiology is Linked to Criminality
Our bodies provide constant feedback about our environment through chemical and electrical signals.
This biofeedback, monitored through psychophysiological measures like heart rate and skin conductance, reflects emotional states like fear and anxiety.
Research suggests that blunted physiological arousal is associated with increased antisocial and criminal behavior.
The fearlessness theory argues that because antisocial individuals don’t experience strong bodily signals of fear and anxiety, they are not deterred from risky, illegal behaviors.
Alternatively, the sensation-seeking theory posits that physiological underarousal is uncomfortable, so antisocial individuals seek out crime to raise their arousal levels.
Impaired physiology may also disconnect bodily states from associated emotions, undermining socialization processes like conscience development.
For example, an inability to sweat or experience a racing heart could make it difficult to learn anxiety helps us avoid consequences.
While studies show robust links between blunted arousal and antisociality, different offender subgroups exhibit different patterns.
Reactive aggressors tend to be hyperaroused while proactive aggressors are hypoaroused.
Treatments targeting associated symptoms, like mindfulness for hyperarousal, show promise.
How Brain Structure and Function Influence Criminality
Advances in neuroimaging have allowed scientists to move beyond correlation and explore the brain structures and connectivity patterns underlying criminal behavior.
Key regions like the prefrontal cortex (PFC), amygdala, and striatum show both structural and functional abnormalities in antisocial populations.
The PFC controls higher cognition like decision-making and impulse control.
Criminals often show PFC deficits, suggesting these impairments contribute to their behaviors.
Brain stimulation studies directly manipulating PFC activity provide causal evidence that PFC disruption increases criminal thinking and intentions.
However, different criminal subtypes exhibit different neural patterns.
Psychopaths with less severe criminal histories show no PFC deficits compared to non-criminals.
The amygdala processes emotions like fear and drives stimulus-reinforcement learning.
While psychopaths tend to show amygdala underreactivity, impulsive criminals demonstrate amygdala overactivity.
Finally, the striatum regulates motivation and reward.
Increased striatal reactivity and altered connectivity are linked to impulsivity and psychopathy.
Though the brain areas involved vary across subgroups, disrupted moral processing is a common factor underlying all criminal neural aberrations.
The Role of Genetics in Criminal Behavior
Studies suggest genetics account for 40-60% of variance in antisocial behaviors.
However, no specific “crime genes” have been identified. This is likely because genes do not act in isolation.
Rather, gene-environment interactions (GxE) and gene-gene interactions (GxG) better explain genetic risk.
GxE studies show certain genes, like MAOA, increase sensitivity to environmental stressors like abuse.
These stressors can then trigger antisocial behavior in genetically vulnerable individuals.
Epigenetics allow life experiences to become biologically embedded and passed down through chemical changes to gene expression.
Meanwhile, GxG research explores genes whose combined effects are greater than their individual effects.
For example, variations of dopamine system genes DRD2 and DRD4 confer heightened criminal risk when present together.
However, gender, ethnicity, and type of criminal behavior moderate these genetic relationships.
Overall, biological explanations should be viewed as complementary to existing theories, not deterministic.
Biological risk factors are flexible and can potentially be counteracted through social interventions.
A holistic, integrative approach will provide the most comprehensive understanding of the causes of criminal behavior.
References
- Study: Biological explanations of criminal behavior
- Authors: Ling et al. (2019)
