Book Talk

Your Brain Is Hardwired to Snap

The same group of neurons could make you a hero—or a rage-filled aggressor.

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Neuroscience can trace the origins of rage to a tiny knot of neurons in an area of  the brain known as the “hypothalamic attack region.” Here, electrodes monitor a man’s brain.


We’ve all been there: Some jerk cuts you off on the highway. You lean on the horn, scream abuse. You want to get out the car and kick the @#$% out of the bozo’s SUV.

Road rage is just one example of what neurobiologist Douglas Fields calls “snapping.” From domestic violence to mass shootings, the news is full of stories of seemingly “normal” people suddenly going berserk. The easy availability of guns only compounds the problem.

But how and why does this happen? The traditional explanation is that these outbreaks of rage and violence are aberrations: the result of moral and psychological defects. But in his timely new book, Why We Snap: Understanding the Rage Circuit in Your Brain, Fields shows that violent behavior is often the result of the clash between the modern world and the evolutionary hardwiring of our brains—and that, unless we understand its triggers, we are all capable of snapping.

Speaking from his home in Bethesda, Maryland, Fields explains what neuroscience is teaching us about rage; how the Baltimore riots were about tribe, not race; and why men are more prone to violence—and heroism—than women.

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In the famous TV show about a serial killer, Dexter says that he is driven to kill by his “lizard brain.” Is there such a thing?

[Laughs] That’s an out-of-date concept, dating back half a century. It’s become vernacular for the snapping rage response but it never was something neuroscientists took as fact. It was a way to simplify some aspects of sudden aggressive behavior. The reason I wanted to write this book is because there’s been so much new information about the brain, and the reality is a lot more interesting than the old lizard brain idea. [Read about new technologies that tell us how the brain really works.]

You were inspired to write this book by an incident while on vacation with your daughter. Tell us about that day in Barcelona and how it affected you.

I was on my way to give a lecture on neuroscience in Barcelona. My 17-year-old daughter was accompanying me. We had a little bit of time before the lecture so we decided to go to the Gaudi Cathedral. We were coming up out of the subway and suddenly I felt something on the pocket of my cargo pants. I slapped it like you’d slap a mosquito, and instantly felt my wallet was gone. Instinctively, I reached back and clotheslined the robber and took him to the ground.

I don’t have any background in martial arts, I’ve never been in the military. I’m not a violent person. What shocked me was that I had instantly responded. This threat in my environment that I wasn’t even aware of unleashed this instant, defensive response. And I wanted to find out why.

You trace the causes of rage and violence to a “tiny knot of neurons at the core of the brain where conscious thought cannot penetrate: the beast within.” Dissect it for us.

A large part of the human brain, just like the brain of other animals, is devoted to threat detection. These circuits are constantly evaluating our internal and external state for threats. This cannot be conscious, because that’s too slow. It’s deep in the brain below the cerebral cortex, where consciousness arises, in a region called the hypothalamic attack region.   

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TV serial killer Dexter attributed his crimes to his “lizard brain.” According to Douglas Fields, this is “an out-of-date concept” with no foundation in science.


The hypothalamus is where a lot of our urges and automatic functions are carried out, like sexual behavior. The hypothalamic attack region controls defensive-aggressive behavior. If scientists stimulate these neurons with an electrode, an animal will instantly become aggressive and attack a test animal in the cage.

Are men more prone to rage and violence than women?

When you look at the subject of aggression there is no more important factor than gender. Something like 90 percent of the people in prison for violent crimes are men. Men have different brains than women, which comes from our different roles during evolution, when the brain was formed. Men had a role of being aggressive, which makes no sense for a woman because a woman was not endowed with the physical strength of a man, who probably outweighs her. But although 90 percent of those in jail are men, 90 percent of people who have been awarded medals by the Carnegie Institute for heroism are also men. In a quarter of those cases, these are men who gave up their lives and died in an instant to do something heroic, often for a stranger. So the rage circuit is good and bad. It’s a double-edged sword.

One of the paradoxes of human nature you explore is that “rage circuits evolved to help us, not to harm us.” Tell us about the passenger on Northwest Airlines Flight 253.

The so-called “underwear bomber” starts to set off a bomb on a plane headed to Detroit. This one passenger hears a pop and sees some smoke, leaps over several rows of seats and attacks the would-be terrorist and subdues him. Afterwards, people ask him why he did that. He says, “I don’t know, I didn’t think.” But all the other passengers around this guy saw the same thing and fled.

We have these circuits because we need them. Most of the time, they work amazingly well. We don’t call it snapping unless the result of this aggressive response is inappropriate. When it works as intended we call it quick thinking or, in many cases, heroic. We have these circuits to protect ourselves, our family unit, or society.

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“All mammals that are social, especially primates and humans, owe their rank in society to aggressive interactions,” says Fields. Here, bighorn sheep butt heads on the edge of a cliff.


You summarize the nine triggers that can prompt violence in a mnemonic: LIFEMORTS. Explain a couple of them and how they work.

I looked at research into the brain that produces sudden aggressive responses; it turns out that there are multiple circuits but just a few things that will set off this response. You’re not going to engage in violence and risk life and limb for a trivial reason. There are very specific triggers. I came up with this mnemonic because it can teach you to disarm the circuit from going off inappropriately, causing snapping.

The “L” in LIFEMORTS stands for Life or Limb: defensive aggression. If attacked, you will defend yourself. “I” is Insult. All mammals that are social, especially primates and humans, owe their rank in society to aggressive interactions, like rams butting heads. And insult is a very common trigger for snapping and rage.

“T” is Tribe. We are fiercely tribal organisms. When our brains evolved, another tribe was usually regarded as a threat. At the same time, our success on the planet resulted from us forming tribes. So we defend our tribal group by violence.

How are the latest discoveries in neuroscience advancing our understanding of rage and violence?

One of the main ways is the realization that there are different circuits for different kinds of rage and defensive responses. This is a really complex problem the brain has solved. We also now understand how this works as a system and are becoming able to trace these complex circuits. My having that response to fight to get my wallet back was automatic. But think how much information-crunching went on in order for that response to happen! We’re learning a lot about the circuitry, when and how it can go wrong, and what influences it. It’s really exciting.

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Last year’s riots in Baltimore, following the death of Freddie Gray, were widely seen as being about race. Fields believes the violence was more about “tribe.” Here, police in riot gear impose a night curfew on May 1, 2015, after the state’s attorney ruled Gray’s death a homicide.


Road rage is a phenomenon of our times. Talk about the clash between the modern world and our evolutionary hardwiring.

We have the same brain we had 100,000 years ago. But we’re now in a really different environment and these circuits of rage and protection get set off inappropriately by situations in the modern world that didn’t exist when our brains were formed. Why are you suddenly enraged when someone cuts in front of you? It makes no sense. It will only make a couple of seconds difference in your journey. The circuit that’s been tripped misinterpreted the situation. Road rage hits all of the LIFEMORTS triggers. It perceives the space around your car as though it was your territory, which trips that “E” trigger to defend your territory or environment. Someone violating the rules also hits the “O” trigger, for Organization. Humans become angry when someone violates the rules.

As part of your research for the book, you went to Baltimore, shortly after last year’s riots caused by Freddie Gray’s death. What were you looking for?

One of the fascinating things I learned through researching the book is how these circuits of rage play out in society, nations, and groups of people. What I found is that these triggers are very much involved in violent interactions between large groups of people.

Initially, the Baltimore riots were interpreted as racially provoked, because a black suspect was arrested and then died of a broken neck in the back of the paddy wagon. That would fit with the “T” trigger, because we divide people into tribes. But, in my opinion, though it was the “T” trigger, it was not about race. Many of the police involved were African-Americans. But the “T” trigger categorized the situation into “us” vs. “them,” with the police being “them.”

We’re constantly dividing people into “us” vs. “them.” And once we put someone in the “them” category, it can open up the floodgates for violence and is the root of a lot of human misery and wars.

WATCH: In images that one researcher likens to a “Google Map” for brains, a deep dive into a mouse’s gray matter shows how its smallest parts communicate, driving the much larger machine of its body.

A problem we are grappling with today is how seemingly normal, Western-educated young men – and women – can join organizations like ISIS and commit horrific acts of violence. What light can neuroscience shed on terrorism?

The root of this problem is not fitting into society. We are fiercely social beings. And if you are a young individual not fitting into society—and failing—you will find a group that will accept you. Many terrorists are fundamentally misfits. They are not successfully integrated and productive in their own lives, so they find a group they can have an affinity with. We’ve seen this for years with gangs. It’s the same with terrorism. They want to belong to a group. They have a cause.

What practical advice can you give our readers about how to control their rage?

The minute you find yourself angry, identify why. If it’s one of the LIFEMORTS situations, you’ll know two things. First, you’re in a situation that is pressing on triggers in the brain designed to produce deadly violence, so you’re in a dangerous situation. Two, if it’s a misfire, you can quickly disarm it.

Stress is often a major factor in snapping. The threshold for pulling all nine of the LIFEMORTS triggers is lowered when you’re under stress. So if you’re held up in traffic and suddenly enraged—ask yourself why am I angry? Anger is an emotion preparing you to fight. It comes when the threat detection mechanism in your brain says, “I detect this threat.” When that happens, identify the trigger.

This interview has been edited for length and clarity.

Simon Worrall curates Book Talk. Follow him on Twitter or at simonworrallauthor.com.

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