Why we are prone to sudden 'snaps' of rage and what we can do to control them

A violent altercation at a Barcelona metro station set US neuroscientist R Douglas Fields on a quest of discovery

Modern conditions such as road rage did not exist when our brains’ defensive circuits of violence were formed (Alamy)

We like to believe that we are in control of our actions, but sometimes we are not. A sudden incident can overtake the conscious will and launch us into violent action that risks our life and limb in an instant. I know, because it happened to me.

I am a neuroscientist, and after witnessing my violent reflexes explode without conscious deliberation, I was propelled on a quest to understand the disturbing behaviour of suddenly “snapping” aggressively – to freeze that moment in time and look inside the brain to find out what is happening when sudden rage erupts without conscious control.

The search took me into scientific laboratories around the world to learn the latest findings on the neuroscience of sudden anger and aggression, and into the field to meet extraordinary people who depend on this rapid-response neural reflex to perform aggressively in some of the most demanding and dangerous situations imaginable: secret-service agents, members of US Navy Seal team 6 and elite athletes engaged in extreme sports. I learnt that the brain is hardwired for sudden violence, and that we have these neurocircuits of rage because we need them. When the results are inappropriate or tragic, we call it “snapping”; but when the outcome is good, we call it “quick- thinking” or heroic. Either way, it is the same neural circuitry that is operating beneath the radar of our conscious mind.

We see this bewildering behaviour as flashes of rage on the road or fits of violence in sports, leaving automobiles, tennis rackets and, sometimes, relationships in ruin. The shocking behaviour ranges from someone “losing it” and raving at a co-worker, a family member, a stranger in a pub or an airline counter, to someone snapping violently and killing someone – even a loved one. Road rage, for example, can suddenly erupt into a violent pursuit between two complete strangers who are now furiously bent on a physical altercation that ends in a motor-vehicle accident or physical assault. A 2015 study by Privilege Insurance found that Brits are likely to experience one road-rage event for every 20 minutes of driving on UK roads. My sudden explosion of violence came out of the blue.

Like most scientists, I travel the world to lecture and collaborate with other scientists, and I almost always travel alone. This time my 17-year-old daughter, who had just graduated from high school, was with me. Just before I was due to speak at an international meeting of neuroscientists in Barcelona, my daughter and I made a quick visit to see the Sagrada Família, Gaudí's cathedral. Ascending the steps out of the dingy metro station smelling of concrete dust and sweat we emerged into the brilliant sunshine. The crowd of passengers pressed upon us in a grey blur.

Suddenly I felt a sharp tug at my pant leg. As if swatting a mosquito I slapped the zippered pocket above my left knee. My wallet was gone! My left arm shot back blindly. In a flash I clotheslined the robber as he pivoted to hand my wallet to his partner and flee down the steps. As if swinging a sledgehammer I hurled him by his neck over my left hip and slammed him belly first on to the pavement, where I flattened him to the ground and applied a head lock. Drawing on junior-high-school wrestling moves from 40 years ago, I found myself applying an illegal chokehold. The street-smart hoodlum struggling in my arms was in his late twenties or early thirties.

At that moment, a question bubbled up to my astonished cerebral cortex: what was I doing? But it was too late. My unconscious mind had already reacted within a fraction of a second to engage me in a street fight with a criminal to get my wallet back. Had I contemplated the situation, I never would have attempted such a thing. No amount of money is worth being injured or killed. Fifty-six years old, 130 pounds, with wire-rimmed glasses and greying hair, I have no martial-arts training, no military experience, no background in street fighting. But now I had no choice. It was a fight.

“Police!” I shouted. “Call the police! I've got him!” There was no reply, no gasps of shock from the dense crowd, no one was coming to my aid. Instead, from my perspective on the ground, all I saw were men's feet closing in around me in a tight circle. They were all part of the gang. Oblivious to being hunted as prey, we assumed that the crowd was the normal throng of passengers bumping and jostling through the Barcelona Metro system.

I did get my wallet back in the struggle, but the street gang proceeded to chase my daughter and me throughout the city for the next two hours in a harrowing pursuit that seemed like a scene in a spy movie. We cut though back alleys, ploughed through noisy restaurants and, finally, stopped a cab in the middle of a three-lane boulevard, jumped in and escaped to a small town an hour away.

It had been a close call for both of us. But how was any of this possible? I just wanted to give a lecture on my new research on purinergic signalling in neuron-glia interactions and maybe take in a little sightseeing with my daughter. Where had I learnt to do what I had done? How, with the lightning-quick reflexes of someone snatching a fumbled coin from the air, had I unleashed such a flurry of moves on my attacker without conscious thought? Would I always react this way if caught unawares?

If something unexpected in our environment can instantly launch us into a violent attack without conscious thought, I wanted to identify and understand those triggers of rage. I wanted to understand how these situational triggers unleash violence by tracing the specific neural circuits inside our brains that are responsible for sudden aggression. If possible, I wanted to learn to control these circuits. I soon realised that the unconscious explosion of violence that was unleashed to protect my daughter and myself in Barcelona is the same behaviour that is triggered inappropriately in so many everyday instances of sudden and regrettable violence, when someone “just snaps”.

Researchers are discovering that sudden violence is launched by neural circuits deep inside the brain that operate beneath the level of consciousness. In confronting a sudden danger, conscious thought can be too slow. Also, the conscious mind could not handle this demanding task. Threat-detection circuitry in the unconscious brain monitors all sensory input coming into the brain, constantly sifting the internal and external situational data in search for dangers. This enormous amount of information-processing would easily overwhelm the conscious mind.

These rage circuits are located in a region of the brain, the hypothalamus, which also controls other powerful automatic bodily functions, such as hunger, thirst, and sexual behaviour. When researchers use an electrode to stimulate neurons in the “attack area” of the hypothalamus, the experimental animal will suddenly launch into a vicious attack and kill a docile test animal placed in its cage. Humans have this circuitry too. Like other animals, our species needs violence for self-defence, to protect our young and to kill animals for food. The question is: what kicks this unconscious circuit into action?

Although it would appear from the headlines that almost anything can flip the switch to unleash the violent beast within us, this is not the case. For any animal, engaging in violence is risky. Only very specific types of provocations will trigger the hypothalamic attack area to provoke a furious response. These specific triggers are each controlled by different neural circuits in the brain. This is a new advance over the outdated concept that a single “lizard brain” inside us stupidly releases beastly impulses.

For example, a mother will immediately attack if her offspring is threatened. This “mummy bear” reflex doesn't take any conscious deliberation – any parent will instantly act aggressively to protect their offspring, because this response is hardwired deep in the brain from hundreds of thousands of years of our species' survival-of-the-fittest struggle in the wild. The circuitry controlling this sudden aggression is separate from the circuit for self-defence, which provokes a violent reaction to being injured by an attacker. When scientists disable the circuit for the “mummy bear” response in the brain of a mouse, the mother will no longer react aggressively to defend her pups, but she will still react violently for self-defence. Disabling the “self-defence” circuit in the brain has the opposite effect.

To more easily remember these triggers of sudden aggression, I devised the mnemonic “lifemorts”(see panel, top right). To itemise the elements in no particular order: the L (life-or limb) and F (family) triggers were just described – buit we and other animals will also react violently to protect our territory (environment), our resources (for a pet dog, this is its food dish, but for people this becomes money and other valuables): in my case, it was the theft of my wallet. Violent aggression will also be unleashed to escape restraint. These are what I call the E (environment), R (resources), and S (stopped) triggers of aggression.

Human beings are dependent on our complex social structure for survival and, like other social animals, we will fight for dominance within our social structure (I for insult) and defend our group (T for tribe), and we use violence to maintain order within society (O for order). Insult is a threat to our social dominance, which in the animal world is determined by aggressive contests. We still use violence to maintain social order. Putting a violator in prison, taking away their property (through, for example, the imposition of fines) or revoking privileges (such as a driving licence) are all types of violence to force compliance with social rules. The O trigger is why we suddenly become angry when someone jumps the queue at the market or while merging lanes on the road. Finally, mammals, and especially primates, use violence to attract and retain mates. “All's fair in love and war” – the mate or M trigger of aggression.

The paradox is that these triggers of violence are a double-edged sword. Angry mobs, gangs, racial strife and war are the ugly dark side of the T (tribe) trigger of violence, but this same brain circuit is the key to human success on this planet – our ability to rapidly form cohesive alliances among groups of people for a common purpose and defence. Selfless acts of heroism are often prompted by the T trigger, in which a person instantly takes aggressive and even violent action to save one's group.

The problem is that these brain circuits evolved when humans lived in a very different environment. Situations in the modern world that did not exist when these defensive circuits of violence were formed can cause misfires – road rage, for example. Kicking and screaming violently can be life-saving, but the same trigger of violent rage can be set off inappropriately on the road. The “stopped” trigger of aggression “knows” about quicksand and being grabbed by the leg by a predator, but cars are 100,000 years in the future from when this circuitry was formed in our brain. This explains why of all the emotions humans might have when stuck in traffic – from boredom to becoming sleepy – we are instead angrily consumed by rage and ready to attack.

The key to preventing such misfires of the brain's rage circuitry is to learn to recognise rapidly the “lifemorts” triggers of rage. When a sense of overwhelming anger suddenly arises, instantly ask yourself if it is being provoked by one of the “lifemorts” triggers appearing in the many subtle variations that arise in the modern world, such as being stuck in traffic (S trigger), or having someone suddenly cut into your lane of traffic (E trigger). Doing this will quickly disarm the response if it is a misfire, because you will know why you are suddenly angry in the biological sense. You will see that the anger and preparation to fight results from a misfire, because a release of violence is not going to be helpful in resolving this situation. Being able to quickly identify the triggers of aggression that explain why one is angry can be much better at defusing anger than trying to “put a lid on it”. Telling someone to calm down when they are angry doesn't help and often fans the flames. (Now you know why – you are pressing on the person's S trigger!)

In addition to knowing the nine triggers, an important factor is that the threshold for pulling each trigger is constantly being adjusted according to internal, external and situational factors. Chronic stress, for example, puts the brain's defensive system on high alert. This happens because the emotion of stress is our unconscious mind evaluating our internal and external environment and concluding that we are in danger. It makes sense to put the “lifemorts” triggers on edge in this situation, but this also means that, under chronic stress, the triggers of rage are more likely to misfire. Knowing this bit of biology will enable you to guard against misfires of the rage triggers in yourself and in others who appear to be under stress.

The modern world – with all its increasing congestion, hectic pace, stress and constant bombardment of our senses with arousing stimuli – puts our brain's threat-detection mechanism on high alert, making it more likely to go off in response to a trivial provocation. We no longer live in small groups, isolated on the planes of Africa or in the jungle. Increasingly, the triggers of rage are being pressed upon in modern life. Global communication at the speed of light and international travel increase interactions between people and this in turn increases the opportunities to set off these triggers.

Now, add the most dangerous component into the mix: new technology (guns, bombs, the internet) that amplifies the destructive effects of sudden violence in an individual well beyond the capability of the bravest among us to confront with bare hands. Finally, alcohol, drugs of abuse and drugs used for treating certain mental and physical illnesses that the brain never encountered until recently all act on the brain's threat-detection circuitry, releasing the brakes on our rage circuit. You can see why people seem to be angrier and more violent – snapping in anger every 20 minutes or so on the road, and at other times throughout our day.

These neural circuits perform a vital, complex function, showing the best and worst of humanity. Mostly, they work amazingly well. Although we are wired for violence, we are not slaves to the beast within us. The conscious mind can activate or inhibit the brain's rage circuits via connections from the prefrontal cortex. Members of Navy Seal team 6 and extreme athletes practice to develop this cortical control of the rage circuit, to exploit it to best advantage – and so can you. Understanding the brain's threat-detection and sudden aggression circuitry is the first step in controlling it. µ

'Why We Snap: Understanding the Rage Circuit in Your Brain' by R Douglas Fields (Dutton, £19.99)

Know your triggers: Threats to one or all of these 'lifemorts' can set you off

L 'life or limb': this is a basic question of self-defence

I insult: whether verbal or physical, we don't tend to respond well

F family: our animal instincts tell us to protect our nearest and dearest

E environment: when someone encroaches on your personal space

M mates: aggressive behavour can be perceived as attractive, especially in the wild

O order: we begrudge those who threaten to disrupt an established system of rules

R resources: for a pet, these might be food and water; for us, they are more likely to be money and valuables

T tribe: we tend to want to defend those with whom we identify, if not biologically (see 'F') then socially

S stopped: when you feel stuck or 'stopped' by a situation or another person, you might lash out (in a traffic jam, for example)