What drives human aggression?

It's not just genes, parents, society, social media, or lack of coffee.

Psychologist Sigmund Freud published Civilization and Its Discontents in 1930. The book describes humans as aggressive beings and civilization as the mechanism to control this tendency. However, the benefits of society, such as increasing the number of things one can do, are barely discussed.

Freud was not entirely wrong. Humans are aggressive, more than most animals. Evolutionists believe aggression evolved as a result of its survival benefits. Instead of producing food, building houses, or finding a mate, you can steal them from someone else. Violent events as old as the Crusades and as new as the Russian Invasion of Ukraine prove we can hurt others who haven't hurt us. 

But he was wrong to assume every human is violent or receives pleasure from violence. Not every person is aggressive, and not every aggressive person will be violent.

Potential cause #1: instincts

It would be ill-suited to call Freud's argument cynical and ignore it. His thesis came from observing the world and his clinical work. Before publishing the book, he lived through World War I, an event where millions of humans killed each other. During the 1910s, he treated around 130 people, working up to sixty-six hour weeks. Patients suffered from depression, a delusion of persecution, and psychosis. War caused and ended many treatments. In the 21st century, we can discover many examples of human malice and kindness. So it's not as easy to develop a pessimistic worldview. But while writing this book, all Freud saw was death, despair, and hostility from war and post-war.

Some modern research backs Freud's thesis about civilization limiting aggressive behavior. 

Political Scientist Harald Wydra says the law protects us from contagious violence. It makes us less likely to repeat The Holocaust, Gladiatorial games, and Middle Age wars by setting boundaries for what we can and cannot do. Less likely is the keyword. In 2022, there are lynch mobs in the US, organized crime groups in Brazil, and militant Islamists ruling Afghanistan. A few years before, humans even stabbed each other over a Popeyes' chicken sandwich. Yet Wydra says there would be more violence if the law didn't exist. 

Psychologist Ervin Staub shows Wydra's assumption is plausible. He shares how, in mobs, anonymity can make people less aware of their actions and instead focus on a group's goals. The chances they act aggressively increase during social climates where change is the norm, like war times. Or when people feel wronged or deprived, like during protests against police violence. Both in mobs and in lawless societies, people are free to do what they want. In mobs, the law exists but can't control citizens, so its benefits are null. 

Potential cause #2: Mobs and leaders

Based on the political, psychological, and evolutionary research I mentioned, Freud sounds right. Humans seem to tend to be aggressive when no systems regulate their behavior. 

But this is not the case. Humans can be aggressive, but instincts do not trigger it. Other people do. Wydra saw that human aggression was always motivated by someone. The wrong leader manipulates people's emotions and frames violence as the solution. Anthropologists Mary Douglas and Gerald Mars found terrorist groups use denigration of the outside world to create loyalty among closed, dissident minorities:

“Black and white dichotomized values, which allow no credit to outsiders, are strategies for exercising a hold on the members: they build a wall of virtue between saints and sinners.”

Mob violence seems to be the exception at first. People are more likely to favor a group's goal than morality, after all. Psychologists Stephen Reicher and Jonathan Potter highlight an issue with this claim: not every person in a mob is anonymous. They might be unknown to the police, but not to the reporter who happens to be your neighbor. So people might be more likely to be violent, but they know there is a system regulating their behavior and it can punish them. 

Potential cause #3: Genes

Though leaders can influence people to be violent, they can't motivate anyone to use it. The person they motivate must have a predisposition to be aggressive. 

Criminologist Kevin Beaver and Psychologist Christopher Ferguson studied if genes made us violent. Their literature review found that genes influence around 50% of the variance in antisocial phenotypes. Vandalism, aggression, and violence are all antisocial phenotypes. They also found the role that dopamine has in making a person violent. Dopamine releases when we do an activity that gives us pleasure. The more pleasure it releases, the more likely we will do that action in the future.

Based on this premise, people who are often aggressive might act that way because they were born with a tendency to feel pleasure from violent acts.

Personality traits also dictate whether a person could be aggressive. A personality trait is a unique way to perceive and judge the world. Here's an example I shared in a previous essay:

"There are millions of ways to react to a car cutting you on the highway. So, instead of making you study every option, personality traits tell you how to judge the situations. A person with high levels of neuroticism will curse the person and honk until their car's battery runs out. But a person with low levels of neuroticism may not even react to the event and keep driving. The situation is the same, but the perception of the events varies."

Psychologists Christopher Barlett and Craig Anderson suggest some personality traits predict aggressive behavior. For their research, they asked two independent samples to fill in three scales. The goal was to see how violent people were, their attitudes towards violent behavior, and if they had an aggressive personality. They found neurotic people can be aggressive when they experience aggressive emotions. People who are disagreeable are also likely to become hostile because they are skilled at noticing and responding to hostile cues. 

Recent research backs these findings and further studies what makes people hostile. Across two studies, they found people who saw themselves as aggressive were more likely to act in that way or have aggressive intentions. 

Potential cause #4: Lack of self-control

But leaders and governments can't manipulate anyone genetically inclined to be aggressive. Researchers from Florida State University say self-control influences whether someone uses violence. Self-control is, in part, learned from parents. Children will have better self-control when parents supervise them and correct their misbehavior. But when parents don't do any of these, children tend to grow up less able to control themselves. Genes also play a role in our capacity for self-control:

“The results of behavioral genetic studies have been quite consistent and have revealed that genetic factors account for between 50% and 90% of the variance in self-control, self-regulation, and impulsivity, whereas the remaining variance is attributable to the nonshared environment and measurement error.”

Thus, humans can be aggressive. And, to Freud's point, some are born with a tendency to be violent and gain pleasure from it. But, not every human is born with this inclination. Nor every human born with it will be violent. 

It takes many emotional triggers to make an aggressive person act violently. And, even if they are present, the ability to control one's emotions can mitigate their effect.