After the attacks on July 22, 2011 in Oslo, Norway, everyone wanted answers. How could such an act occur in a democracy of reasonable people? This was being debated from the angles of politics, religion, and sociology. I wanted to ask this from the point of view of neurobiology.

The brain is the most complex device we have ever discovered in the universe. Weighing three pounds and consisting of tens of billions of specialized cells woven in intricate patterns, it is the seat of our behavior, our beliefs, and our actions. If you were to injure your small toe in an accident, you’d be saddened, but your conscious experience would be no different. By contrast, if you were to damage an equivalently sized piece of brain tissue, this can change your personality entirely—thereby unmasking the veiled workings of the machinery beneath. Through centuries of observations of brains (and brain damage), it has become clear that our hopes, fears, ideas, desires, and behaviors are all rooted in this mysterious organ.

Like all brains in the animal kingdom, human brains are driven by reward and motivation systems that are steered by hunger, thirst, and sex. But in humans—and presumably uniquely so—political ideologies can also come to steer these systems. Humans can override other basic social instincts in deference to beliefs—whether religious, racial, or nationalistic. Take, for example, the concept of a hunger strike, which overrides basic food demands in favor of a larger purpose.

So how can we comprehend the events in Oslo? First, it is important to understand that brains are like fingerprints: they are not the same in everyone. Instead, along any dimension that we measure, we find that brains are quite different from person to person. Inner lives can be unrecognizable between one brain and the next.

So the first lesson we must confront with Breivik is that we cannot guess what it is like to be inside his head. We will almost certainly remain without a satisfying explanation for his decision-making—not because he is unwilling to offer an explanation, but because his justifications are not within the borders of our shared, societally-average cognition.After all, we are each constructed from a genetic blueprint, and then born into a world of circumstances that mold our brain development. Many of us like to believe that all adults make choices in roughly the same way. It’s a charitable idea, but it’s demonstrably wrong. People can be vastly different, reflecting the unique patterns of neurobiology inside each of our heads. The complex interactions of genes and environment mean that all citizens—equal before the law—possess different perspectives, dissimilar personalities, and varied approaches to decision-making.

Given the variation in brains, there has been a trend in courtrooms toward attempting to mitigate a sentence by evidence of bad biology or bad experiences. In other words, is there something in a law-breaker’s genes or childhood that predisposed him, unfairly, toward this kind of behavior? But I submit that searching for biological excuses moves us in the wrong direction, because it rests on a strange question: Was it his fault, or his biology’s fault? From a neuroscience perspective, that question no longer makes sense, because we now understand decision-making and biology to be inseparable. The choices we make are yoked to our neural circuitry, and therefore there is no meaningful way to tease the two apart.

Some people worry that the more we understand about the relationship between brain and behavior, the more we will be tempted to say that law-breakers are not blameworthy—and then no one will be found guilty for his crimes.

But this is an empty worry. Biological explanation will not exculpate criminals. We will still remove from the streets law-breakers who prove over-aggressive, under-empathetic, and poor at controlling their impulses.

Consider, for example, that all known serial murderers were abused as children. Does this make them less blameworthy? Who cares? It’s the wrong question to ask. The knowledge that they were abused encourages social programs to prevent child abuse, but it does nothing to change the way we deal with the particular serial murderer standing in front of the bench. We still need to keep him off the streets, irrespective of his past misfortunes. The child abuse cannot serve as an excuse to reduce his sentence; the judge must take action to keep society safe.

Instead of letting law-breakers off the hook, deeper biological insight into behavior will allow a better understanding of recidivism—and that will offer a basis for rational, evidence-based sentencing. Some people will need to be taken off the streets for a longer time (even a lifetime) because their likelihood of reoffense is high; others, due to differences in neural constitution, are less likely to recidivate.

In other words, instead of trying to untangle the hopelessly complex web of genetics and environment that forms the trajectory of a human life, there’s a more fruitful question to ask: what do we do, moving forward, with an accused law breaker? The legal system has to become forward-looking, primarily because it can no longer hope to do otherwise. As biology complicates the question of culpability, our legal and social policy will need to shift toward a different set of questions: how is a person likely to behave in the future? Are criminal actions likely to be repeated? What is his future dangerousness?

In the case of Breivik, we can never know the minutiae of his biological history; our task is to determine what to do with him from here.


So what can we can say about Brevik’s brain? First, it’s important to note that if you were to examine the brains of most people in prison, you would find there is no such thing as a “criminal brain”. Lawbreaking can be a complex tangle of personality, background, circumstance, and opportunity. For example, imagine that you grew up in a poor, rough neighborhood. It’s likely you’d become a member of a gang. You might even be a very talented gang member who rises to the top and is later punished accordingly. In the same way that we are not separate from our biology, we are not independent of our social fabric. This is why, under most circumstances, we cannot jump to conclusions that there is something wrong about a law-breakers’ brain.

However, when the social fabric around a person is good, the situation is different. Vastly abnormal behavior that appears in a peaceful, healthy society is generally a good indicator of a brain abnormality.

Breivik grew up in a middle-class district of Oslo and attended an elite high school. In his manifesto, Breivik describes his youth as “happy”. His life in Oslo was peaceful and secure. Given these circumstances, behavior so far out of the norm is indicative of a deeply pathological brain.

One might argue that despite the appearance of a healthy society, in fact Breivik was surrounded by an extremist subculture. But note that even among the far right, his behavior is anomalous. Oslo has not had any public demonstrations from the far right since the 1990s. Breivik seems to believe that his actions were part of a larger movement; however, while it is true that he is not alone in his political opinions, his actions distanced him irreversibly from his crowd.

One might further argue that scapegoating a group of people is not so unusual; consider the histories of Nazi Germany or Rwanda. But Breivik’s approach of murdering children of the Labor party, instead of targeting the scapegoated group itself, is so deeply aberrant that it distinguishes itself from the usual direct attack on a reviled group.

Given the abnormal behavior, will neuroscientists be able to measure something wrong with Breivik’s brain, such as a tumor? Probably not. Neuroimaging remains a crude technology, and pathologies can be subtle, hidden in the details of the microcircuitry. If brain imaging yields no obvious difference in Breivik’s brain, this will only tell us of the limitations of our current technology—not whether there is or is not a deep biological problem.

To summarize, even if we cannot measure anything wrong with a mass murderer’s brain, we can assume that something is abnormal. His actions are sufficient evidence of a brain abnormality, even if we can’t yet measure the details. As the neuroscientist Wolf Singer recently put it: “As long as we can’t identify all the causes, which we cannot and will probably never be able to do, we should grant that for everybody there is a neurobiological reason for being abnormal.” Note that most of the time we cannot measure an abnormality in criminals. Take Eric Harris and Dylan Klebold, the shooters at Columbine High School in Colorado, or Seung-Hui Cho, the shooter at Virginia Tech. Was something wrong with their brains? We’ll never know, because they—like most school shooters—were killed at the scene. But we can safely assume there was something abnormal in their brains. It’s a rare behavior; most students don’t do that. Even students who are bullied, lonely, and looking for attention don’t do that. Similarly with Breivik: although there are many disgruntled members in the political right wing, almost none take up arms against children and other innocents.

To be sure, debate will rage about what psychiatric label to give Breivik. Is he a psychopath? This seems supported by the emotionless nature of his slaughter and his lack of remorse; on the other hand, it’s not necessarily consistent with the reports that he defended other children against bullies when he was younger. Is he a paranoid schizophrenic? This seems plausible in light of his deeply-held conspiracy theory that Christian Europe is being annexed by a collaboration of Muslims, Marxists, and multiculturalists; on the other hand, Breivik was obviously influenced by his subculture of politically like-minded people. Further, his writing appears generally clear, even while extreme in its views. A psychiatrist quoted in the New York Times reported that he saw “no overt signs of mental illness in Mr. Breivik’s writings.”

Psychiatrists will have to spend time with him to make further determinations. In the meantime, his extreme behavior tells us much of what we need to know to determine his future dangerousness.

Citizens will invariably interpret Breivik’s act as an unsettling sign of the times, a bloody commentary on Muslim-European relations. But his act may instead represent only an isolated neural phenomenon, a Rorschach Blot upon which individuals will superimpose their own interpretations. Breivik’s doings are the product of a pathological brain, one that in another time would have found another issue to turn his wrath toward, just as the Unabomber in America had a similar approach but an entirely different set of issues.

As for his likelihood of committing crime in the future, his highly deviant behavior suggests a rational basis for maximizing his sentencing. In Norway the maximum prison sentence is 21 years—but at the end of that term the prosecutor may petition the court for “preventive detention.” This gives the court the option to extend the sentence for five years if the person is deemed to be a continuing threat to society. These five year increments can be added indefinitely. If I had to guess now, I’d wager that Breivik will be locked away for the rest of his life. After all, in a democracy every person is welcome to hold his own constellation of political opinions so long as social order is maintained. Breivik has proven himself unworthy of participating in such a system.

David Eagleman is a neuroscientist at the Baylor College of Medicine in Houston, Texas. He directs the Initiative on Neuroscience and Law (, and is the author of Incognito: The Secret Lives of the Brain.

Eagleman DM (July, 2011), “Breivik’s Brain”, originally published in NZZ am Sonntag (Switzerland), Politiken (Denmark), and The Independent (UK).

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