Viernes, 02 Julio 2010 17:15

B. Are we Inherently Aggressive?

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One aspect of the concept of man as a rational animal is an implicit mental model that defines human beings as inherently aggressive and violent. This section contains a critical analysis of a few of the arguments that are often used to promote this idea: that we have an instinct for aggression and territorialism, and that we have ‘violent brains’. An argument that is often put forward to justify war and other acts of violence is that they are determined by a 'killer instinct' in human beings. Some ethologists –scientists who study animal behavior– have proposed the existence of human instincts for territorialism, aggression and war, which they suggest could have been inherited during our evolution from other animal species.


A. Do we have a ‘Killer Instinct’?

We have wandered so far from the other species in the evolutionary process that their behavior has little or nothing to do with ours. Even if we did share some common ancestor millions of years ago, each species has gone its own way since then in response to its peculiar living conditions.

When a carnivorous animal goes hunting for food, this is no more an act of ‘murder’ than when one of us goes to the store to buy meat. War is not a natural act, but a cultural invention of human beings. No other species makes war, whether within the same species or with other species, aside from human beings. In fact, several of the primate species that are most similar to humans evince remarkably peaceful behavior.

What is instinct? Traditionally, this term was used to refer to any ‘automatic’ response, even if it was the result of education, socialization, or acculturation, as we se in the following quote from “Roads to Freedom” by Bertrand Russell: “If a man is offered a fact which goes against his instincts, he will scrutinize it closely, and unless the evidence is overwhelming, he will refuse to believe it. If, on the other hand, he is offered something which affords a reason for acting in accordance with his instincts, he will accept it even on the slenderest evidence.

However, as science has advanced, in this case biology, many terms that were once hazy have been clarified. Currently, instinct is scientifically defined as a repetitive pattern of specific and often complex behaviors that are common to an entire species, automatic, irresistible, unalterable, and do not depend on learning. None of the human behaviors that scientists have studied thus far meet this definition, so it is currently believed that human beings are entirely devoid of instincts.

Let us not confuse instincts with reflexes, biological predispositions and drives. A reflex is a simple, automatic reaction to a stimulus, which does not involve the higher functions of the brain but comes directly from the spinal cord or even more local nerves, such as the kick caused by striking just below the kneecap. A biological predisposition is an innate behavior, but is more complex than a reflex and requires learning to express itself, such as walking or speaking. A drive is rooted in a biological need such as hunger and grows in intensity until it is satisfied.

The attitudes of aggression, competition and greed, so common in today’s society, do not fulfill any of these definitions. Rather, they involve a broad range of alternative, culturally established behaviors. They are only a few of the many options available, one of the many ways we can respond to a given situation, while caring, cooperation and generosity are the ones that best meet our collective needs on the long run.


B. What about war?

Soldiers are often represented as war machines, motivated by an inner force that drives them to kill in cold blood, without a thought for their own lives. However, under normal conditions, youth are entirely devoid of these murderous, suicidal feelings and behaviors. In fact, Dave Grossman, a lieutenant coronel of the US army who has specialized in teaching young soldiers to kill, says this is not as easy as it sounds. In 1995, Grossman published the results of a study that showed that most soldiers refuse to kill and never actually shoot their rifles in combat.1 He quotes from the book “War – the Lethal Custom”, by Gwynne Dyer, a professor of military studies, who has found that:

There is such a thing as a "natural soldier": the kind of man who derives his greatest satisfaction from male companionship, from excitement, and from the conquering of physical and psychological obstacles. He doesn't necessarily want to kill people as such, but he will have no objections if it occurs within a moral framework that gives him a justification–-like war–-and if it is the price of gaining admission to the kind of environment he craves. Whether such men are born or made, I do not know, but most of them end up in armies (and many move on again to become mercenaries, because regular army life in peacetime is too routine and boring).

But armies are not full of such men. They are so rare that they form only a modest fraction even of small professional armies, mostly congregating in the commando-type special forces. In large conscript armies they virtually disappear beneath the weight of numbers of more ordinary men. And it is these ordinary men, who do not like combat at all, that the armies must persuade to kill. Until only a generation ago, they did not even realize how bad a job they were doing.2

Most recruits come to military training with the peaceful sentiments that are common to the masses of humanity, and must be psychologically 'rewired’ through conditioning and training, to exchange sensible rationality for blind obedience, human solidarity for nationalistic fanaticism, and reflexive prudence for suicidal fervor.3 Grossman describes in some detail the sophisticated modern methods of brainwashing and desensitization that are used to overcome the natural resistance to kill, in order to raise up a new generation of soldiers. If human beings had a ‘killer instinct’, such reprogramming would not be necessary.

Howard Zinn is an historian, peace activist, professor of Political Science at the Boston University and author of over 20 books. In a widely-disseminated, video-taped interview, he shares his own experience in the military service as follows:

I have always found that, in any discussion on war, inevitably, there is a certain point in the discussion where somebody says: ‘Oh well, it’s human nature.’ There are still people who talk about the desire of young men to go to war, to shoot their guns to kill.

I thought about my own experience in the air force, and it was very clear to me, looking at all these guys around me dropping bombs and killing people, that it didn’t come from the inside, thinking, ‘God, how good it would be to kill some people today.’ There was no urge to kill, even though they were the ‘enemy’. Where it came from, was simply that we had been trained. Also we had been told that it was a ‘good war’. We are the ‘good guys’ and they are the ‘bad guys’, it’d be good if we won and it’d be bad if they won. So we’ll do it. But there was no spontaneous urge to kill. This experience simply recoiled at the idea that the soldiers, young men, have a kind of killing instinct.

Then when I got away from my own experience and just began to study history of wars, something else became clear to me. Wars don’t take place out of the rush of the population demanding war. It’s the leaders who demand war and prepare the population for war. If there was a spontaneous urge to kill, why do we have to draft?4

This nationalist fervor, which leaders incite in their citizens to fan the flames of war, is a relatively new phenomenon. Jared Diamond states that the will to fight for one’s country,

…is so strongly programmed into us citizens of modern states, by our schools and churches and governments, that we forget what a radical break it marks with previous human history… Such sentiments are unthinkable in bands and tribes… Naturally, what makes patriotic and religious fanatics such dangerous opponents is… their willingness to accept the deaths of a fraction of their number in order to annihilate or crush their infidel enemy. Fanaticism in war… was probably unknown on Earth until chiefdoms and especially states emerged within the last 6,000 years.5

Rather, for war to appear as a socio-structural invention of the modern state, we have had to go beyond instinct and develop the intelligence capable of achieving such a profound alteration of our natural leanings towards peace that normally characterize human beings. In the Seville Statement on Violence we read:

It is scientifically incorrect to say that war is caused by 'instinct' or any single motivation. The emergence of modern warfare has been a journey from the primacy of emotional and motivational factors, sometimes called 'instincts', to the primacy of cognitive factors. Modern war involves institutional use of personal characteristics such as obedience, suggestibility and idealism, social skills such as language, and rational considerations such as cost-calculation, planning and information processing.

The technology of modern war has exaggerated traits associated with violence both in the training of actual combatants and in the preparation of support for war in the general population. As a result of this exaggeration, such traits are often mistaken to be the causes rather than the consequences of the process.6


C. Do we have a ‘Violent Brain’?

One of the arguments that support the mental model of an aggressive human nature is the notion that we have a ‘violent brain’. Specifically, some point to the ‘primitive brain’ and the fact that it enables a person to become extremely violent. Perhaps the first scientific work on this topic was the pioneering book by Vernon Mark and Frank Ervin, titled Violence and the Brain, published in 1970, in which they clarify that there is nothing in the brain that can induce a normal person to violence.7

It is true that animal and human brains have a ‘limbic center’ that makes it possible for us to experience fear and anger, among other feelings that are important for our survival. However, a normal person’s brain does not generate these emotions on its own, but rather in response to external stimuli and their interpretation as threats, similar to how a healthy brain does not produce the sounds that we hear but only enables us to perceive and interpret them.

The limbic center is surrounded by regions of the brain whose function is to moderate, control, channel, and limit the expressions of that fear and anger. They help us interpret a situation’s threat level and decide how to respond in order to protect ourselves from danger. Using these functions, we can purposefully stimulate the limbic center and intensify our feelings of fear or anger in preparation to respond, or use those same functions to voluntarily calm ourselves and tranquilize our bodies. Education and training have a powerful influence on the way we handle this.

It is also true that localized brain damage and other mental illnesses hinder our control of emotions such as fear and anger, whether because they alter their intensity in the limbic system, or because they impede the moderating functions of other parts of the brain. They often appear in the form of attacks that are similar to certain types of epilepsy, whose victims can lose not only their control but also their memory. These ailments can be caused by extreme malnutrition, the use of certain drugs, blows to the head, etc., and tend to be intensified by the use of alcohol and other external stimuli.

However, one cannot define the nature of the entire human race by the pathologies of a small percentage of the population. Just as the normal state of the human body is not determined by a small percentage of broken bones, we cannot define human nature by a small proportion of damages to the brain and mental illnesses.

Some studies have taken the opposite tack and suggested that human beings have a ‘peaceful brain’. For example, there is one center that controls our artistic and holistic abilities, another one that gives us feelings of peace and happiness, and in the frontal cerebellum they have even found what seems to be the center that enables us to perceive the mystical experience of the presence of God.

Which of these two extremes should we give credence to? The violent brain or the peaceful brain? It is as if one study stated that your head turns left, and another that it turns to the right, and you were asked to determine which was correct. Both, of course! Human brains provide us with the entire range of sensations, feelings and emotions that make up the breadth and depth of the human experience. We are the ones who choose which to give importance in our lives and how to act in response to them. The “Seville Statement on Violence” clarifies this point:

It is scientifically incorrect to say that humans have a ‘violent brain’. While we do have the neural apparatus to act violently, it is not automatically activated by internal or external stimuli. Like higher primates and unlike other animals, our higher neural processes filter such stimuli before they can be acted upon. How we act is shaped by how we have been conditioned and socialized. There is nothing in our neurophysiology that compels us to react violently.8

There are currently several academic organizations that conduct scientific research regarding the brain and violence. One of the most important is the Coloquio Internacional sobre Cerebro y Agresión (CICA), which has held more than 30 meetings on four continents with thousands attending, in addition to publishing some 18 written works. CICA maintains that “There is no human function which does not involve both the brain and the social context.”9


Study Questions:

After reading the text, answer the following questions in your own words:

• List some of the arguments for a ‘killer instinct’ in human beings, followed by the reasons they are not valid.

• What is the technical definition of an instinct?

• What do modern biologists say about human instincts?

• Is it scientifically correct to say that humans have a ‘violent brain’? Why or why not?

• What are some of the alternatives that the author proposes?




1. Grossman, Dave. "On Killing: The Psychological Cost of Learning to Kill in War and Society”. Boston: Little Brown and Co., 1995.

2. Dyer, Gwynne. “War – the Lethal Custom”. New York: Carroll & Graf Publishers, revised edition, 2006.

3. See the story (in Spanish) of “A Soldier who Never Wanted to be One” and the ways they tried––unsuccessfully––to instill in him a warrior attitude, at

4. Zinn, Howard. “On Human Nature and Aggression”. URL:

5. Diamond, Jared. “Guns, Germs and Steel - The Fates of Human Societies”. New York: W.W. Norton & Company, 1997, p. 281.

6. UNESCO, “Seville Statement on Violence” written and signed by 20 Nobel Laureates for the International Year of Peace in Seville, Spain, on May 16, 1986.

7. For further information, see Vernon Mark and Frank Ervin. Violence and the Brain. San Francisco: Harper and Row, 1970.

8. UNESCO, 1986.

9. English URL:

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