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By Gene Bylinsky
From FORTUNE, January 1973, pp. 134-146.
Research associate: Bro Uttal

Article republished with permission of Gene Bylinsky and FORTUNE. Please pay a visit to their website in return.

New Clues to the Causes of Violence
Enraged animals, such as this rhesus monkey at Tulane University, are helping scientists to shed new light on how the brain governs violent behavior. Reared in isolation, the monkey attacks other animals, and even the researchers working with it, at the slightest provocation. It has been established that raising monkeys and other animals in isolation alters the biochemistry, and perhaps the circuitry, of their brains. Somewhat similar changes may affect improperly raised children who grow up to be violent.

Assassinations, vicious muggings, and the high and rising U.S. murder rate have pushed the subject of violence to the forefront among American concerns. At times, the nation appears to be oddly fascinated by the phenomenon, Consider, for example, the recent proliferation of grisly movies, some of which seem to glorify violence as a cult. We have been hearing an abundance of theories about the causes of violence, which variously attribute it to the war in Vietnam, to permissiveness, to drug addiction, to racial frustrations, and even to the legacy of the wild frontier.

Now science is venturing into this area of speculation and dispute. A broad interdisciplinary effort is getting under way to explore the biological nature and origins of violence. Biologists, biochemists, neurophysiologists, geneticists, and other natural scientists are probing with increasingly precise tools and techniques in a field where supposition and speculation have long prevailed. Their work is beginning to provide new clues to the complex ways in which the brain shapes violent behavior. It is also shedding new light on how environmental influences, by affecting the brain, can trigger violence. In time, these insights and discoveries could lead to practical action that may inhibit violent acts–perhaps, for example, a change in the way children are brought up, or treatment with "antiviolence" drugs. Such preventive steps might in the long run be more effective in controlling violent crime than either "law and order" or social reform.

By tradition, students of aggression and violence have been divided into two separate camps that hardly ever communicated with each other. On one side stood the ethologists, students of animal behavior in the wild, many of whom held that man is biologically fated to violence. At the other extreme were social scientists, who knew, or cared, little about biology. They argued that violent crime is strictly a social phenomenon, best dealt with by eliminating slums, urban crowding, and racial discrimination, and by alleviating poverty and improving the prison system.

An imprint on the brain

The most recent research suggests that the biological and environmental causes of violence are so closely intertwined as to require a less fragmented search for remedies. The research is showing, among other things, that the environment itself can leave a physical imprint on a developing brain. The wrong kind of upbringing can make a young animal, and probably a child too, more inclined to violent behavior as an adolescent or an adult. The hopeful augury of this research is that such behavior can be prevented if steps are taken to assure that young brains develop properly.

Until a few years ago, scientists knew comparatively little about the intricate inner mechanisms of the brain that initiate and control violence. These mechanisms lie deep in an inaccessible area called the limbic system, wrapped around the brain stem, as shown in the drawing on page 136. In the limbic system, the hypothalamus stands out as the single most important control center. Regulating many of man's primitive drives, its networks of nerve cells, or neurons, direct not only aggressive and violent behavior but also the states of sleep and wakefulness, as well as sexual and feeding behavior. The front part of the hypothalamus contains networks of nerve cells that promote calmness and tranquillity. The back part regulates aggression and rage.

Restraining the hypothalamus

Nearby lies the almond-shaped amygdala, which restrains the impulses from the hypothalamus. Another close-by structure, the septum, seems to inhibit messages from both the hypothalamus and the amygdala. The cerebellum, the large structure at the back of the brain, filters sensory impulses. The hippocampus, a short-term memory bank in front of the cerebellum, is importantly involved in ways that brain researchers do not yet adequately understand.

All these structures are functionally as well as anatomically interrelated. Electrical signals, arising in response to sensory or internal cues (e.g., sight or thought), speed along nerve pathways to activate or block the function of other nerve cells. Chemicals such as noradrenaline and dopamine, which are normally present in the brain and are known as neurotransmitters, apparently ferry these electrical signals across the tiny gaps between nerve cells, called synapses, to such control centers as the hypothalamus. At the same time, the neurons are constantly bathed in waves of background electrical activity. In still unknown ways, this background "music" apparently conveys information, too.

So complex are the organization and function of the human brain that some of its estimated 10 billion nerve cells may have

p. 136, FORTUNE, January 1973

as many as 100,000 connections to adjoining cells. When an aggressive act escalates into a violent one, apparently more and more of these neurons are recruited to create bigger pathways for the flow of pulses. Thus violence, as some scientists define it, is aggression gone awry.

The Human Brain
The brain's decisions about violence are made mainly by some of the structures depicted here. The centers that initiate aggressive acts, such as the hypothalamus, lie deep in the primitive part of the brain called the limbic system. Man's more intellectual cortex exercises a restraining influence over the lower brain regions. The brain, scientists speculate, reaches decisions much as a democratic society does. Individual neurons sort out conflicting impulses and decide whether to fire an electrical pulse or not. The sum of such decisions tells a person, for instance, whether to lash out at an enemy or to remain calm.

The case of the enraged cat

Fortunately for the advance of knowledge about human aggression, the limbic systems of animals have recently been found to bear an amazing functional resemblance to that of man. So laboratory experiments with animals (notably monkeys, cats, and mice) underpin the still limited investigations of aggression systems in the human brain.

Using fine electrodes inserted into animal brains, researchers have induced a fascinating range of aggressive behavior. Cats that normally do not attack rats, for instance, will stalk and kill a rat when stimulated in a certain area of the hypothalamus. On the other hand, a cat stimulated in anothei nearby region of the hypothalamus may ignore an available rat and attack the experimenter instead. Destruction of the nucleus of the amygdala will turn a friendly cat into a raging beast that claws and bites without provocation, because the signals from the hypothalamus are no longer dampened by the amygdala.

Similarly, a tumor in the hypothalamus or the amygdala can turn a peaceful person into a violent one. Such tumors occur infrequently. Corrective brain surgery remains highly controversial, however, mainly because surgeons lack precise knowledge of the aggression systems and know little about the risk of unwanted side effects from such operations. A surgical lesion–a scar-producing cut, freeze, or burn intended to destroy tissue–can increase or decrease hostile behavior, depending on its location.

Similar gaps in medical information inhibit manipulation of aggressive behavior with drugs that structurally mimic the neurotransmitter chemicals. Recent experiments by Peter Bradley, a British neuropharmacologist, show that a brain cell can be affected in different ways by the same neurotransmitter, depending on the state of the cell, the amount of neurotransmitter, and how often the chemical is administered. It also appears that during an aggressive act a general arousal of the physiological system occurs-the same type of arousal that can be produced by such peaceful activities as jogging or even a concentrated mental effort.

Dynamite in the genes?

The complex anatomical and biochemical systems of the brain get their "orders" from the genes that determine behavior. Recent studies suggest that males have more brain cells that specialize in aggression, than do females. This means that boys are more likely than girls to inherit aggressive tendencies. Very little is yet known, though, about the relationship between specific genetic defects and violence, how many such defects exist, and how frequently they might be inherited. Among the handful of anomalies discovered so far that some scientists have connected with violent behavior is the famous extra Y chtomosome, which luckily appears to be inherited by fewer than two men in a thousand. (X and Y are sex chromosomes, with a normal male having an X and a Y, and a normal woman two X's.)

The Y chromosome leaped from the quiet of the laboratory four years ago and landed with a splash in newspaper headlines and courtrooms. The XYY males, usually tall, were said to have a natural propensity for violent crime. Some lawyers tried to gain reduced sentences or acquittal for their clients on the basis of their real or imagined extra Y chromosome. In France, at least, one attorney succeeded.

Some imaginative work now in progress at the University of Connecticut suggests that the Y chromosome story isn't all

p. 137, FORTUNE, January 1973

that simple. Researchers in the department of biobehavioral sciences, led by Benson E. Ginsburg, a noted geneticist, have designed animal breeding techniques that allow thern to "tease out," as Ginsburg puts it, the contributions of individual genes and chromosomes to behavior. Their findings strongly hint that an XYY male's tendency to aggressiveness depends on whether he inherited his extra Y chromosome from a peaceful or aggressive father. The Y chromosome may act on the brain through the male sex hormones. Ginsburg and other scientists are trying to find out how this process works.

Elevating genetic probing to a new level of precision, Ginsburg and his colleagues have also shown that a Y chromosome from an aggressive father can combine with another genetic anomaly to make an animal twice as aggressive as it would be with just one genetic defect. They worked with an inbred strain of mice known as DBA 1. These mice are genetically susceptible to epileptic-type seizures that can be initiated by a high-frequency sound from a buzzer, or a bell, or even a jangling set of keys. The sound activates an enzyme system, controlled by a gene as all enzymes are, and located in the hippocampus. In a mouse, the network of neurons involved makes up an area the size of a pinpoint. The enzyme activated by sound, nucleoside triphosphatase, generates epileptic-like brain waves that can be recorded.

Investigating violent behavior in children, James W. Prescott and Albert Bandura have developed widely differing, but not necessarily conflicting, theories to explain the phenomenon. Prescott, a neurophysiologist at the National Institute of Child Health and Human Development, holds that much violence has biological underpinnings, specifically brain damage caused by improper upbringing. His theory covers both monkeys and people. Bandura, a psychologist at Stanford University, is a prominent proponent of social learning theory. He contends that whether a person responds violently to stress depends greatly on what he has seen or been taught. For his experiments, Bandura used large, inflated plastic dolls, one of which can be seen in the background, being walloped by a boy who had watched a doll beaten in a demonstration.
James W. Prescott
James W. Prescott
Albert Bandura
Albert Bandura

Stormy weather in the hippocampus

The DBA mice, particularly males, are abnormally aggressive, apparently because of the defect in their hippocampus. In such mice, complex chemical reactions are superimposed on abnormal electrical activity in their hippocampal neurons. "You whip up an electrical storm in that region of the brain," says Ginsburg, describing his work with a touch of poetic license. Chemicals in the brain intensify the storm, he says, "as if you poured gasoline on a fire–and it went whoosh!"

The same type of storm, and in the same spot, rages in the brains of certain humans. They are either pathologically aggressive or have been made aggressive by hippocampal stimulation. This suggests, of course, that Ginsburg and his colleagues have found a genetic anomaly underlying aggression in both mice and men. In recent years, surgeons in some hospitals have been stimulating different parts of the brains of cancer patients in an effort to find an area that might block unbearable pain. In a number of instances, where doctors have stimulated the hippocampus by administering a very mild electrical shock through an electrode, patients showed the type of rage that Ginsburg and his associates found in those DBA mice. One mild-mannered patient in his fifties suddenly brandished his bedpan as a weapon against the nurses and whoever else happened to be around. He later felt quite embarrassed and contrite.

The discovery of the consequences of these anomalies and of other types of brain damage shatters the assumption made by criminologists and sociologists that the vast majority of cases of violent behavior involve people with completely normal brains. Studies of criminals who have repeatedly committed violent offenses show that they have a higher incidence of brain

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damage than the general population. Moreover, recent research is uncovering subtle forms of brain damage, unrecognized until now. No one knows for sure how many people in the U.S. suffer from brain damage, but some doctors place the number at 10 million to 20 million. Not all of them are violent, of course, but in addition there are many thousands who suffer from delusions or other forms of mental disturbance that make them dangerous. David Hamburg, head of the psychiatry department at Stanford University Medical School, estimates that the nation harbors some 200,000 potential presidential assassins. "Many manage their delusions on the fantasy level," says Hamburg. "Others engage in other forms of violent behavior."

What many people with brain abnormalities may have in common are pathways in the brain that failed to develop properly in infancy because of faulty upbringing, just as visual nerve pathways fail to develop properly in animals deprived of light. The fault, especially during the first two years of life when the brain is growing the fastest, lies in lack of physical affection, which an infant needs as much as nourishment. Earlier researchers had usually blamed emotional, social, or learning deficiencies for behavioral disturbances in infants raised in a foundling home. But James Prescott, a young neuropsychologist at the U.S. National Institute of Child Health and Human Development, suggests that there is a more fundamental biological reason. He maintains that normal pathways in the brain do not fully develop in children deprived of Such expressions of affection as touching, cuddling, and being carried about. Instead, he says, this "somatosensory deprivation" leaves them with damaged central nervous systems.

Detective Work in the Lab

Aggressive and violent behavior is being investigated in four different ways by these scientists. Donald J. Reis, a neurobiologist at the Cornell Medical Center in New York City, operates on the brains of cats in order to induce violent behavior. Harry F. Harlow, a psychologist at the University of Wisconsin, was among the first to find that rhesus monkeys become unusually aggressive when raised in isolation. By combining computer analysis with electroencephalography, Robert G. Heath and Bernard J. Saltzberg, brain researchers at Tulane University, are developing a way to detect disturbances deep in the brains of aggressive monkeys. Robert M. Llebert, a psychologist at the Stony Brook Campus of the State University of New York, studies the impact of televised violence on children by videotaping their facial expressions as they watch.

Donald J. Reis
Donald J. Reis
Harry F. Harlow
Harry F. Harlow
Robert M. Liebert
Robert M. Liebert
Robert M. Liebert
Robert G. Heath and Bernard Saltzberg

A chicken-wire mother

In a dramatic series of experiments, Harry F. Harlow, a University of Wisconsin psychologist, has demonstrated what happens when baby rhesus monkeys are deprived of their mothers. Harlow placed an infant monkey in a cage with two inanimate mother substitutes. One, covered with terry cloth and equipped with bicycle-reflector eyes, was designed to feel and look somewhat like a real rhesus mother but had no apparatus for feeding the infant. The other "mother," made of unadorned chicken wire, was unattractive to touch but contained a baby's bottle from which the infant could drink milk. Harlow found that the infant rhesus clearly preferred to spend all of its time with the nonfeeding surrogate. Even when feeding from the chicken-wire "mother," the infant would cling to his terry-cloth favorite. Harlow concluded that in infant mother love, holding and cuddling are even more important than feeding. He also found that female monkeys who grew up

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with mother surrogates failed to develop maternal affection: they all seemed indifferent to their own children. Like parents who abuse their children, these monkey mothers frequently attacked, and sometimes even killed, their infants. Other researchers have recently traced three generations of human parents who batter and abuse their children. The only common characteristic of such parents, regardless of social or economic class, was that they themselves had suffered from lack of mothering and affection. Harlow wryly concluded a recent paper:

Hell hath no fury like a woman spurned.
With love not given, love is not returned.
The loveless female, human or macaque,
In place of love will substitute attack.

Can such deprived, aggressive monkeys be restored to normalcy? Experiments in Harlow's laboratory indicate that rehabilitation is possible if it is done early enough. Young monkey mothers reared in isolation sometimes regain most of their normal maternal behavior when locked in a cage with their own babies. The infant clings to the mother so persistently, despite her efforts to push it away, that eventually the baby monkey begins to serve as a therapist. Similarly, some young male monkeys reared in isolation become less aggressive when forced to play with monkeys their own age or younger.

Research into the brains of monkeys raised in isolation is just beginning, but indirect evidence already hints that such treatment induces brain damage. In humans, brain waves with abnormal, jagged "spikes" are often a telltale sign of damage. Robert G. Heath and Bernard Saltzberg, researchers at Tulane University, have recorded such spikes in the brain waves of monkeys reared by Harlow. The spikes reflect abnormal electrical activity, particularly in the cerebellum.

Why Ding feared Dong

Further evidence of the cerebellum's role in violence comes from the work of A. J. Berman, a neurosurgeon at Mount Sinai Medical School and the Jewish Hospital in Brooklyn. He has successfully modified autistic and aggressive behavior in isolation-reared monkeys by removing presumably abnormal sections of cerebellum that deal with the reception of sensory signals. In one experiment, Berman performed similar surgery on two monkeys called Ding and Dong, who had fought viciously and continuously. The operation turned Ding into a submissive animal, while Dong remained as aggressive as ever. Berman attributes the difference to the location of the surgery. Some tissue was removed from the midline section of Ding's cerebellum while the excision on Dong was microscopically closer to the side of that brain structure.

Berman suggests that his findingq may one day be relevant to treating humans. "Walk into the back wards of any mental institution," he says, "and you'll find children whose behavior is identical with that of Harlow's monkeys."

All these and many other experiments have led a number of scientists to conclude that people who behave overaggressively may have an abnormality in the mechanism by which they perceive pleasure. In animals reared in isolation, as in pathologically violent people, the impulses resulting from the stimulation of movement and skin sensations may not be reaching their normal destinations in the brain. The feeling of pleasure may thus be experienced only partially or not at all.

This may explain, among other things, why both institutionalized children and monkeys brought up in isolation generally rock back and forth for hours on end and respond violently if touched. Adults with damaged pleasure systems similarly may be trying to derive pleasure from the rough physical contact involved in violent acts; they may, in effect, be seeking an additional stimulus. Researchers have also found that electrical stimulation of pleasure centers in the brain eliminates feelings of rage, because the brain seems to contain rival nerve systems that suppress opposing emotions chemically and electrically.

The scientist plays victim

Aggressive behavior doesn't necessarily have to arise as a result of damaged networks of nerve cells; it can be easily learned, too. Albert Bandura, a pioneering psychologist at Stanford University, demonstrated almost a decade ago how effectively aggression can be taught through the power of example. He used as "victims" large, inflated plastic figures known as Bobo dolls. Small children watched both real-life and filmed attacks on the dolls, then were given an opportunity to act aggressively themselves.

In study after study, researchers discovered that boys, especially, easily learn and retain aggressive behavior. They readily act out what they have learned not only on Bobo dolls but on other children and even adults. In one typical and recent experiment, conducted by psychologist Robert M. Liebert and his associates at New York State University at Stony Brook, kindergarten children watched a short film. Later they spontaneously attacked a scientist who had appeared in the film dressed up as a hard-luck clown and had been beaten up by another researcher. Many studies show that televised violence affects children in similar ways.

Violent behavior can be set off by many other environmental conditions. For instance, Leonard Berkowitz, a University of Wisconsin psychologist, showed that the mere presence of firearms can stimulate aggressive action. He tested groups of students who were provoked and insulted by one of his colleagues. Later, the groups had a chance to administer electric shocks to their tormentor. Students in a room where a gun was casually displayed gave the investigator about 25 percent more shocks than those in a room containing no weapons. The findings suggest to Berkowitz and others that easy access to lethal weapons–about 65 percent of homicides in the U.S. are committed with guns–not only facilitates the commission of crimes but creates an atmosphere in which violence is more likely to occur.

As in the laboratory, violence in real life often begets more violence. Marvin E. Wolfgang, a noted criminologist at the University of Pennsylvania, has coined the term "subculture

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of violence" to describe the cluster of values, attitudes, and life styles prominent among the poor living in the slums. Violence in that setting is so common as a problem-solving mechanism, says Wolfgang, that there is no shortage of real-life models for the young to imitate.

Many other factors–frequent absence of fathers, low income, unstable employment, poor living conditions–also bend the behavior of underprivileged youths toward violence, according to Wolfgang. Under all these pressures, plus in some cases a lack of physical affection at home, adolescent blacks have the highest homicide rate of any group in the U.S.

To complicate matters, they, like other adolescents, undergo a hormonal upheaval. Boys in particular become more aggressive as the amount of sex hormones in their bodies increases. Electron microscopy at Oxford University has recently begun to reveal structural differences between males and females in such control centers of aggression as the hypothalamus, for which sex hormones have a particular affinity.

Are men stronger than mice?

The still mysterious workings of hormones on the brain constitute only a small part of the enormous gap between what scientists have discovered and what remains to be learned about the physiology and biochemistry of violence. For example, says Benson Ginsburg, the University of Connecticut geneticist, scientists should find out whether men, through conscious control and training, can override the physiological changes involved in aggression much more effectively than, say, mice can. Another unknown is whether genetic instructions are so strong in some people as to completely mold their behavior. Answers to such questions could open the way to far more specific therapies. More effective antiviolence drugs, for instance, could be developed if we could delineate the particular enzymatic mechanisms in the brain that affect aggression.

Treatment with existing drugs, many scientists feel, is something like using a shotgun where a rifle is needed. Even so, some investigators propose that methadone-type clinics be set up to dispense drugs available now to persons prone to violence. Lithium might be useful because it appears to speed up the release of serotonin, a brain chemical that seems to inhibit aggression. Michael H. Sheard, a Yale neuropharmacologist, has had some success in modifying the behavior of violent prisoners with lithium.

Other novel approaches may emerge from studies that are under way. For example, development of a vastly improved brain-wave recording machine, now in progress at Tulane, would enable doctors to detect signals of trouble from deep in the brain without surgically implanting recording electrodes there. It may also become possible to treat damaged deep-nerve networks ultrasonically, thereby avoiding surgery.

It is clear that much more specific therapies than those in use today are needed for people who have brain damage. Vernon H. Mark and Frank R. Ervin observe in their recent book, Violence and the Brain: "Hoping to rehabilitate such a violent individual through psychotherapy or education, or to improve his character by sending him to jail or by giving him love and understanding–all these methods are irrelevant and will not work. It is the malfunction itself that must be dealt with, and only if this fact is recognized is there any chance of changing his behavior."

No trouble in Tahiti

To prevent brain damage that may lead to violence, some new tactics could be tried now. "Changing child-rearing practices is probably the most important single thing we can do as a society," says Prescott. "We have to make sure that the children we have are wanted children." Prescott and others also suggest that it might be a good idea to evaluate and treat children as early as age five if they show a tendency to brutalize other children or animals or have episodes of uncontrolled rage. Such youngsters, scientists say, are good candidates for violent behavior later.

Anthropologists have gained some intriguing clues about child-rearing by studying peaceful societies. Prescott surveyed data from forty-nine primitive cultures and found in thirty-six of them an amazingly strong correlation between physical affection toward infants and lack of violence. In societies where infants were treated cruelly, violence prevailed. Robert Levy, an anthropologist at the University of California at San Diego who has studied tranquil Tahiti, found that parents on the island seldom punish children by hitting them. Thus the children have no aggressive models to emulate.

Another deterrent to violence may be the habit of arguing it out. Societies that have developed highly elaborate ways of verbalizing violence are quite peaceful. In Tahiti and other Polynesian islands, people engage in "talking out acute anger, rather than taking physical action," says Levy. Similarly, Italians sometimes sound violent, but according to scientists who have studied Italy, there is far less incidence of violent offenses there than in the U.S.

This nation leads the advanced industrialized countries of the world in homicide and other violent crimes. Assaults in the U.S. occur nearly twice as often per capita as in England and Wales, and robberies are ten times as common. In 1971, the latest full year for which figures are available, 17,630 People in the U.S. were murdered. In England and Wales, West Germany, France, and Italy, which have a combined population about 3 percent larger than ours, there were only 1,948 murders–a rate almost ten times lower than that in the U.S.

By contrast with the U.S., these other industrial countries have more homogeneous populations, exert greater control over firearms, and operate with somewhat more rigid social structures. These differences may explain some, though not necessarily all, of the disparities in the rates of violence. In any case, it is clear that our methods of dealing with the problem have not proved particularly effective. Scientific investigation at last is beginning to provide surprising insights into why this is so. In time, the new research may lead to a much broader understanding of violent behavior, and, eventually, to effective means of discouraging it. – END

Text republished with the kind permission of Gene Bylinsky and FORTUNE. OCR and HTML by Erik Möller. Please tell me about any spelling or OCR mistakes you find. If you know of any translation, or if you want to write one, please contact me. I am also interested in more material on the same subject.