Theories of motivation: Biology

So what are some of the key approaches to understanding why people commit murder?

Some theorist suggest that biology is responsible for people becoming perpetrators of murder, with a number of different aspects of biology considered.

One example of this would be that higher testosterone levels (or pre-menstrual syndrome) are related to heightened levels of aggression and violence.

Or alternatively, someone’s biological response to alcohol or drugs may lead them to be more likely to commit violent crime or homicide.

There is no firm evidence to confirm that there is an association between someone’s physique and criminality, yet it is a topic that continues to be widely researched.

There are also claims that aspects such as a low IQ, which is predominantly determined via inherited genes cause someone to be more likely to commit homicide because of their lack of foresight and inability to see right from wrong.

Research into Central Nervous System dysfunctions has suggested that murderers had much lower glucose uptake in the prefrontal cortex of the brain, linking ideas that abnormal brain functioning may predispose someone to violence.

Defects in the neurotransmitters – serotonin, dopamine and norepinephrine have also been linked with violent, impulsive behaviour.

There has also been work identifying links between a low resting heart rate and violent or anti social behaviour. A study (The Cambridge Study) indicated that twice as many boys with resting heart rates of 65 beats per minute or lower were convicted of violence than the remainder. Do you want to test their resting heart rate now?

It is always important to consider the drawbacks of research before making conclusions. The majority of these studies, although indicating some link between biology and violence, were based on very small sample sizes and therefore are difficult to generalise. Studies will commonly use populations that aren’t representative – such as people pleading insanity defences.