Understanding the Mind of a Criminal: Is it Nature or Nurture?

By JP O Malley on at

Until the early 20th century, all theories attempting to explain the anti-social behaviour of criminals was intrinsically linked to the discipline of biology.

Up until that point in history, biological theories and criminology, were almost inseparable.

By the end of the Second World War, however, knowledge began to emerge about the despicable crimes the Nazis had carried in the name of biology. Namely, eugenics and “racial hygiene”: which aimed at nothing less than eliminating habitual offenders from society. And so ideas thereafter, connecting criminal behaviour to biology, were firmly rejected and consigned to the dustbin of history.

Or, so everybody thought.

Over time, biological theorising eventually made a comeback. Only this time around, it eschewed the inhumane traits of criminology's darkest hour. Gone were the deterministic, anti-environmentalist explanations of the earlier period; and, crucially, it ignored simplistic arguments that split criminal behaviour into neat little dichotomies, like nature vs nurture.

Presently, what has emerged in the field of studying criminal minds is what's known in criminology as the biosocial model: this recognises that while we are all biosocial beings, social factors pertaining to criminal activity also act on biology too.

In simple terms: we are now beginning to see criminal behaviour as a combination of both biology and the environment, in very intricate and complex ways.

Political Divides

In The Criminal Brain: Understanding Biological Theories of Crime, Chad Posick and Michael Rocque — two American academics in the field of criminology — attempt to prove how biological and social causes of crime twine together inseparably, constantly interacting with one another.

The book is a meticulously well researched work of dedicated team scholarship. The first edition was written by a globally renowned professor of Criminology at Northeastern University, Nicole Rafter, who died earlier this year.

Posick and Rocque have now updated the first addition, with two new chapters, while also revising, and complementing other parts of their mentor and teacher's earlier work.

As the dark lessons of 20th century European history has taught us, explanations of criminal behaviour, and political allegiances, usually go hand in glove.

Today, liberals— generally but not always — tend to view biological theories on criminal behaviour as an effort to shift responsibility away from social factors that cause crime, and onto criminal individuals instead. Conservatives, meanwhile — as a general rule of thumb— tend to go in the opposite direction, embracing biological theories more enthusiastically.

“[Theories of criminal behaviour] certainly have a tendency to divide politically,” Posick admits when I ask him about this.

“A lot of sociologists, who tend to be more liberal, are a little weary of biological theories,”  says Posick.

“And rightfully so. Because as we know, they were used in totalitarian states—  most notably in Nazi Germany in the 1930s, using things like straight biological IQ, and racial background—  as the staple for intervening in the eugenics movement.”

“Whereas conservatives tend to lean to the biological side a little bit more,” Posick adds.

When we are trying to closely study the underpinnings of criminal behaviour, however, we shouldn't let politics come into it, both authors believe.

Instead, they argue, we should be guided by empirical science.

This is easier said than done though, because politics and the science of studying criminal minds are so interrelated - and this is where value judgements and cultural-racist prejudices are never far from view.

Both Posick and Rocque are keen to point out that a sense of balance is needed here: they certainly want to give credit to, and understand biological theories; while also taking into account the dangers that a full tilt towards biological based theorising could lead to.

A worst case scenario, for example, could include a future in which far right demagogues introduce crime-control screening programmes based on biology: such as preventing offenders from reproducing.

Lessons From The Past

Both authors believe that by putting these themes into a historical context, society can then try to draw lessons from those egregious examples in criminology of the past, and use them in a balanced way going forward in the future.

Two rather daft theories from yesteryear are worth mentioning. Physiognomical studies: where Johann Caspar Lavater, in the late 18th century, put forward a theory which tried to link outward appearances to mental states that could potentially encourage committing crimes. Then there was the concept of phrenology: a radical 19th century theory which attempted to read a person's character by looking at the contour's of their skull.

Such bizarre theories of crime and punishment may appear rather daft in hindsight. But Posick and Rocque are keen to point out that crazy ideas in the world of criminology have a consistent track record of gaining momentum in a climate of political instability or fear.

And so, they say, a disastrous scientific enterprise— such as what occurred in Hitler's Nazi Germany— could easily happen again.

Moreover, if we want to prevent such a recurrence, then we must acknowledge that all science, because it develops in a social context, is to some degree politicised.

“We do not think that science is completely value free,” Rocque confirms, with authority and self assurance.

“There is a tendency amongst criminologists that sees objective free science as the goal,” he adds.

“But in a [political context] how science is interpreted can be used for really bad purposes. With the voting in of [President-elect] Donald Trump in the United States, we are seeing that we are not immune to missteps like this. So we just need to be really cautious as to what these findings [in the field of criminology] mean, and how they should be interpreted.”

“What we are saying,” Posick weighs in: “is that we have to be careful that science shows us that in criminology it's both the environment and biology. To emphasise one over the other is extremely dangerous. We need to learn lessons from the past. And if we start ignoring these environmental factors, well, that could be really disastrous.”

That said, both authors are keen to point out that biological theories of criminology are always advancing and developing as scientific knowledge increases.

The Evolution of the Criminal Mind

Take the theory of evolution as a case in point.

Traditionally in criminology, any ideas associated with crime and evolution, would have quickly descended into broad brush strokes of pseudoscience: where social Darwinism and unapologetic racism would have quickly reared its ugly head.

But as our knowledge in recent years about genetics and evolution has become more advanced— more specifically with the decoding of the genome, and more generally, with the the intensified study of gene-environment interactions — we are now beginning to learn that a great deal of anti-social behaviour is adaptive and survives in the population.

“Evolution is just the means by which genes exist over time,” Posick explains.

“So this is just a way of looking at criminal behaviour as genetic and evolutionary, in conjunction with the environment. So to completely ignore evolution, and how it has shaped our genetic makeup, is a real misstep,” he adds.

A theory called the differential susceptibility hypothesis adds some weight to this argument too.

Rocque explains this idea in simple detail, unpacking it step-by-step.

“This theory argues that there are certain genetic variations, where some people are more influenced by the environment than others,” he explains.

“And so if you have these risky genes, and you are in this environment, you are more likely to go along with the flow,” Rocque adds.

“However, if you don't have these type of genes, and you are in risky environments, then you might be just fine. So that is a building block in which the environment and biology can be used to build a really powerful explanation of [criminal] behaviour.”

Psychophysiology & Neuroimaging

During the late 20th century, criminology underwent a serious cultural shift when neurophysiologists produced two new types of research. The first was called psychophysiology: a speciality that investigates relationships between psychological states and physiological conditions like heartbeat rates. The second involved neuroimaging: this employed technological advances to peer into the brain to study its structures and functioning.

Research in both areas came to the same conclusion: implicating the brain's prefrontal cortex with antisocial behaviour.

Posick explains the findings in some detail.

“Well we have two major parts of our brain: the limbic system, which brings out the automatic stress response. This is the old reptilian part of our brain. This largely develops at about 15 years of age when we enter puberty. Then you have the pre-frontal cortex, which is the more reasoning part of our brain, where self control and reasoning is housed. This puts the breaks on our limbic system. So our limbic system kicks in and our pre-frontal cortex puts the breaks on our emotional response of our limbic system.”

“But what we find is that a lot of people who commit anti-social behaviour don't have much of a breaking system. They have an underdeveloped or damaged pre-frontal cortex, which makes it difficult to control that emotional part of their brain. And the pre-frontal cortex isn't full developed until about the mid 20s. That is why we might see a lot of delinquent behaviour among adolescents. Because they don't have that fully developed emotional part of their brain, while their reasoning part is lagging behind for maybe about a decade of their life.”

Studying the endocrine system— the collection of glands that produce hormones that regulate metabolism, growth, development, tissue function, sexual function, reproduction, sleep, and mood, among other things in humans—is something that both Posick and Rocque spend considerable time looking at in their latest book to talk about criminal behaviour.

As they both point out, the endocrine system produces hormones like testosterone and cortisol: a long line of research shows that high levels of testosterone are related to high levels of aggressive and violent behaviour. Dopamine, meanwhile, which is a neurotransmitter that is part of the endocrine system, has also been linked to criminality and psychopathy.

Posick says that there are certain gas peddles, as well as breaks, in our biological system. Both help prevent certain anti-social behaviours.

“Dopamine is that gas peddle, whereas serotonin—another neurotransmitter that creates well being and happiness — seems to be that break peddle in our system.”

Both are good. But when there is some kind of imbalance between those chemicals,  Posick explains, then we start to see problems in behaviours.

“One of the things about dopamine is that it gets us excited, it gives us a sense of euphoria. When we eat, sleep, or engage in sexual intercourse—things that as biological beings we need to do— it releases dopamine. If we don't have serotonin, that puts the break on that, or enzymes that break apart those neurotransmitters, that's when we start to have trouble.”

“Generally, when dopamine is high and serotonin is low, we see anti-social behaviour more prevalently, says Posick.

Nature vs Nurture

From the early 21st century, in the field of criminology, there has been an explosion of research on biological risk factors on certain individuals who may have a higher propensity to commit crimes than others.

And yet, even in spite of all the advances in studies of genetics, neuroscience, and with the ability to now look at brain patterns through technologies like FMRI (Functional magnetic resonance imaging) scans, we still understand that crime in inherently a social event.

A kind of social exchange, even if it's a very negative one at that. It frequently involves close contact, and, on the part of both the perpetrator and the victim, a close reading of the other's mind.

Some people, both Posick and Rocque argue, are more predisposed through their biological makeup, to commit a crime than others. But no one individual is ever destined to become a criminal.

“If you look back to a couple of centuries ago,” says Posick  “biology was the big theory put forward to explain nearly all criminal behaviour.”

“But it didn't really incorporate what we know about the environment and sociology. What we are beginning to see now in the study of criminal behaviour is a combination of both biology and the environment. It's how these things work together. We now have the technology, and the insight, to start combining both the environment and biology to further our understanding of [criminal behaviour]”.

The Criminal Brain: Understanding Biological Theories of Crime, is available now.