Stress of War, Conflict and Disaster

By George Fink

Stress is a universal phenomenon that impacts adversely on most people. Following on the heels of Stress Science: Neuroendocrinology and Stress Consequences: Mental, Neuropsychological and Socioeconomic, this third derivative volume will provide a readily accessible and affordable compendium that explains the phenomenon of stress as it relates physically and mentally to war, conflict and disaster. The first section will be dedicated to study of the link between stress and various forms of conflict. Specific instances of conflict will be discussed - the Gulf wars, Korea, Hiroshima bombing, the Holocaust, 9/11, Northern Ireland, terrorism in general, torture. The second section will explore the stress impact of more general physical disasters such as airline and vehicle accidents, earthquakes, floods, and hurricanes. The final section will focus on the clinical relationship between conflict stress and various mental diseases – PTSD, suicide, disaster syndrome, etc – as well as the adverse impact of stress on human physical health in general.

Comprised of about 100 top articles selected from Elsevier’s Encyclopedias of Stress, the volume will provide a valuable desk reference that will put relevant articles readily at the fingertips of all scientists who consider stress.

• Chapters offer impressive and unique scope with topics addressing the relationship between stress generated by war, conflict and disaster and various physical/mental disorders
• Richly illustrated with over 200 figures, dozens in color
• Articles carefully selected by one of the world’s most preeminent stress researchers and contributors represent the most outstanding scholarship in the field, with each chapter providing fully vetted and reliable expert knowledge

• Language: English
• Publisher: Academic Press
• Release date: Nov 25, 2010
• ISBN: 9780123813824

Book preview

Anthropology

Human Nature, Views of

James C. Davies    Eugene, OR, USA

Introduction

Some Earlier, Mostly Philosophical Views of Human Nature

Innate, that is, Natural Sources of Tension

Some Research in the Neurophysiology of Assertive and Violent Behavior

From Here, Where?

Further Reading

Introduction

People’s views of human nature are part of their general attitude toward their fellow beings. The general attitude derives more from experiences than from formal learning. The experiences that produce views on this very basic matter begin at birth and continue through childhood, adolescence, and at least early maturity. One’s religion, one’s political orientation, and one’s attitude toward his or her fellow beings are very stable. The durability of these influences is confirmed by the persistence of opposing, incompatible views on religion, politics, and human nature. Millions of people are Christian or Muslim or Confucian or Buddhist and few of them ever move from one of these religions to another. The same is true in politics. And the same is true in views of human nature.

It is important to appreciate that the systematic or casual views people have of human nature are altogether a product of experience. That is, views of human nature are not themselves innate and thus are subject to change. But they change very slowly. If individuals start life in families and neighborhoods that are high in violence and later experience nonviolent interactions in solving problems, they may change to a less violent view of human nature. If individuals start life with minimal domestic violence and later experience violent interactions, they may more easily retain or re-establish a less violent view of human nature. Individuals from a stable, relatively nonviolent culture may go to war and kill. These killers are not usually regarded as dangerous when they return to civilian life.

It is important to appreciate these aspects of attitude formation because the attitudes are so important. Violence is often a life-or-death matter, and the wrong attitude can be deadly. Furthermore, these views involve both objective and subjective influences and inevitably involve considerations of moral right and wrong. The distinction between ‘is’ and ‘ought’ is very hard to define and harder to realize. People maintain confidence that their views of religion, politics, and human nature are both correct and morally right. Realization of these problems is a necessary first step to moving beyond the ill-considered views of human nature that are so seldom revised after childhood.

A practical definition of human nature is seldom offered: natural scientists say that it is vague definition and then offer nothing specific. Let this definition serve as a basis for discussing views of it. Human nature is the set of determinants of behavior that generate within the human organism and ultimately within the genes.

It is very, very difficult to separate out, to abstract, these determinants because of two factors: the genetically established organism is influenced even before birth by several neurochemicals that pass through not only the placenta but also the blood–brain barrier. These prenatal influences, perhaps the earliest experiences, cannot be regarded as innate, but they so affect the developing fetus that they quite surely are permanent. Infants whose mothers took heavy doses of narcotics like heroin as at young adults became hooked themselves.

Such prenatal influences may be called second nature, but as the fetus becomes an infant and grows through childhood to adulthood, it is most unlikely ever to become conscious that these prenatal events are not genetic. In one experiment a pregnant rat was injected with testosterone. Its female pups became more aggressive than females not subjected to infusion of abnormal, unnatural amounts of prenatal testosterone.

In addition to prenatal influences, there is a steady stream of influences that commences with the first contacts with mothers, fathers, family, neighborhood, etc., and continues throughout life. Even though they may seem natural they are not but can be clearly described as second nature.

Some Earlier, Mostly Philosophical Views of Human Nature

Not all the writers mentioned in this section described themselves as philosophers. Indeed some of them – notably Hobbes and Freud – scorned the term. Nonetheless, they are here included as philosophers on the assumption that their observations arose mainly from their individual experience rather than scientific investigation, experimentation, and validation. This is not to say that these viewers of human nature were wrong but that, in their views of human nature, they were not acting as scientists.

Aristotle, in a relatively peaceful time in Athens, looked at violence causally though he used somewhat different language than is used today. He concluded that revolution is caused by subjective inequality: when inferior, people enter into strife in order that they may be equal, and when equal, in order that they may be greater. Aristotle was the tutor of one of the most successfully violent rulers of all time: Alexander the Great. Nonetheless, his statement (Aristotle, Politics, p. 379) anticipated by more than two millennia of George Orwell’s succinct aphorism about life in the very unjust Animal Farm. In that anti-Utopia the ruling elite had total control of both power and ideology: everyone is equal, the elite said, but some are more equal than others. It is perhaps more accurate to describe Aristotle or Orwell not as prescient but as intuitively basic in his analysis. They both said that human beings naturally expect to be regarded as equals, if not more so: as it would now be expressed, and as Lasswell put it, people want dignity and power.

Thomas Hobbes provides an example of environmental influences that profoundly affected his view of violence. He was in exile from the persistent and frightful wars of the Protestant Reformation in seventeenth-century England. He was thus a participant observer in this very violent century in England’s history. He viewed human nature as inherently, innately violent and said this tendency is controllable only if people surrendered their power of self-rule to the sovereign. Hobbes did not work into his system recognition that people want other things in addition to power. The inevitable implication of his conclusion is that self-rule is impossible, and he did not consider that in the English Reformation, people who lacked power were forcibly demanding it and – if they won enough battles – taking it. That is, Hobbes did not consider that people want equality, in power and other things, and that they turn violent, when they are denied equality and power.

Plato, also more than two millennia before Hobbes, proposed government by the guardians, by vesting total power in the active intellectual elite. Unlike his successor Aristotle but like his successor Hobbes, Plato did not adequately address the problem of who governs the governors. Both philosophers avoided logically facing the fact that rulers also are human beings and so much appraise their own violent tendencies. They viewed human beings from their philosophically elitist standpoints and assumed that ordinary human beings and elitists who were denied power did not want it: they just wanted to fight.

Sigmund Freud’s greatest contribution to the science of human behavior was his insistence that unconscious influences not only exist but also are very powerful. He brilliantly applied and used his contribution mainly in the analysis of childhood experiences as they affected adult sexual behavior. He was less successful in applying his study of the unconscious to nonsexual behavior (and he tended to sexualize the nonsexual) and he did not clearly distinguish sexual from other forms of love, like, for example, agape.

Freud experienced World War I, the meatgrinder of millions of soldiers on both sides, from the viewpoint of Germany and the Central Powers. One of his sons saw military service. His early reaction during that war was to say that as German victories extended, they would spread German culture more broadly throughout the world.

His later reaction was to observe with growing horror the enormous violence and to conclude that violence is an innate tendency. He elevated it in his theoretical system so that in addition to the positive, life-producing (sex) instinct in his earlier theorizing, there was a murderous death instinct that produced destruction not only of others but of the self. In 1933, he collaborated with Albert Einstein in an exchange published as Why war. In it Freud chided some presumptions of Einstein, noting that all sciences have their unexamined first assumptions. And Freud did not well examine either his own assumptions or their origins.

The here-significant facts are that Freud was influenced by his (adult) experience and that this influenced, indeed determined, the construction of his basic orientation. If the world war served only as a reminder and not a determinant, it speaks ill of Freud that he was unable to include a death instinct before the war. If violence indeed is an innate tendency, it is quite an oversight in Freud not to see such an elemental tendency among Homo sapiens.

World War II produced a similar spate of writing that likewise concluded that mankind are innately aggressive, innately violent. Perhaps among the most noteworthy writers was Konrad Lorenz, whose book On aggression (1966) was enormously popular following its original publication, two decades after Lorenz served as a medical doctor in the Germany wartime army in German as Das sogenannte Böse in 1963. His conclusion was the same as Freud’s, though not in the same language: mankind are naturally aggressive, presumably with the exception of Lorenz.

Similarly, in two superbly written books, African genesis (1961) and The territorial imperative (1966), an American writer, Robert Ardrey, likewise proposed and concluded that mankind are naturally aggressive. In the popular discussion of these postwar books, M. F. Ashley Montagu, an anthropologist, was a dissenting voice. He lambasted natural aggressionists for declaring that the violent behavior that is common in war is natural.

The discussion, perhaps starting with the Biblical slaying of Abel by his brother Cain, has been endlessly inconclusive. One cannot satisfactorily demonstrate that general observations are false because they are a product of experience with war. However, one can question the verity of the conclusion by noting a couple of (in)conclusions.

The first is an assumption that rather evidently underlies the conclusion that mankind are naturally aggressive (or have a death instinct). The unexamined assumption is that human beings have a natural need to survive ‘and have no other natural needs’ – except possibly to form groups, to associate. This assumption can be derived from too simple a reading of Darwin’s emphasis on the struggle for survival and the desire to perpetuate the species.

But to assume that because they want to survive, people have a natural desire to aggress avoids consideration of the means–end relationship between aggression and survival. It seems clear that survival is pursed for its own sake, but it seems also clear that aggression is undertaken as a means to achieve not only survival but also other natural ends like the solidity, the integrity, of various groups with which individuals identify; and perhaps the pursuit of equal dignity. It is no more reasonable to ignore the fact that equality was given as a major reason in 1776 for Americans to throw off the British colonial yoke than it is to ignore the inclusion of equality that was included in France as a justification for its revolution.

In sum, a few philosophers and theorists have made without examining it a large assumption that survival is the only natural need. They have tended to ignore the fact that human beings have enormously developed brains that furnish the potential not simply to develop an understanding of natural phenomena but also to identify and empathize with ever-wider segments of their conspecifics. Does this tendency to identify come altogether from the environment? There is a tendency among some philosophers and social scientists to separate themselves from the rest of humanity.

Almost universally, people seem to prefer activity – even at times turbulence – to stasis. But they do not seem to prefer violence. If violence is pursued naturally and for its own sake, then the best humankind could maximize everyone’s opportunity to engage in it: to have, as Hobbes observed, a perpetual war of each against all. If violence nevertheless is undertaken as a means of achieving things that have inherent value and producing inherent satisfaction, then it is important to probe deeper into both definition and examination of human nature.

Its discussion need no longer be left to philosophers or to theorists in psychology. Because it is possible to learn more about human nature by scientific investigation, it is possible to diminish the use of violence as a last-resort means of accomplishing ends that are naturally desired and that provide inherent satisfaction. The problem is akin to that facing global explorers and navigators in the fifteenth century: if you no longer suppose the Earth is flat, it is much easier to get around the globe. The problem is also akin to cosmic navigation: if you no longer suppose that space and time are independent factors, it is much easier to try to explain the universe.

Describing and evaluating views of human nature is a grievous problem, because views of it are very much the product of experience, and experience varies widely and people cling to their views stubbornly. Even people who are well educated and those without formal education have their view. The major difference between those without formal education and the rest is that literate people are better able to articulate their view, but they are not much better at appraising human nature.

The reasons for such a view of views of human nature are elemental: from birth onward, each individual is influenced by events that impinge directly on each individual. If these earliest events include violent experiences, there is a great likelihood that violence will be considered natural, just as if these earliest events include supportive, affectionate interactions, the individual will incline toward a benign and amicable view of others. If those who readily engage in violence are close to a very young observer, a child, it is more likely to regard violence as innate to all people. If others – ranging from neighbors to nearby communities to other nations – are less likely to engage in it, violence is more likely to be regarded as an acquired rather than as an innate tendency.

These seemingly speculative generalizations are, in other contexts, not regarded so speculatively. Social scientists do not often question why they are more likely to find immediate interpersonal violence among people who have been raised in violent families. And they are more likely to find violence on the grand, international scale among a people who feel threatened with violence by people of other nations. When such grand-scale violence strikes home, in the form of an air raid by the enemy or by the loss of a family member, the inclination to regard violence as an innate tendency is increased.

What seems to be fundamental to these speculations is that views of violence are a function of experience with it, whether in childhood or adulthood, whether the violence is perpetrated by a family member, a local community, or a nation. And fundamental to regarding violence as innate or not is the fact that it threatens injury and even death: that is, views of violence are in part a function of the experience of threat to survival.

In sum, the very earliest environmental influences underlie everyone’s view of human nature and these early imprinted influences become so ingrained as to become second nature. Views of violence become second nature. And few people are willing to believe that their view of human nature is highly subjective and imprinted rather than innate. Each person believes that his or her view of human nature, whether or not it includes violent tendencies, is an objective judgment about reality.

If these speculative observations are not wrong, then the process of describing and evaluating views of violence is very difficult indeed. If they are not wrong, then the unconscious, imprinted origins must be looked at, in order to approximate somewhat closer a scientific view of the innateness of violent tendencies.

A start toward understanding aggression and violence as they relate to views of human nature can be made by defining them. There has been critical vagueness in defining aggression. Lorenz uses the term agonistic behavior, and so do J. P. Scott and others. It is used to get around the knotty problem of defining intent. Agonism means forceful action against some part of the environment. Agonism avoids considering intent and avoids judging whether agonistic behavior is bad.

There would be no problem for humankind and for perpetrators and victims of agonistic action if they were merely forceful interactors. We would be dealing in the realm of competition and perhaps with action that is heedless of its consequences. Forceful interaction may be undertaken with the intent of helping the object. A surgeon wielding a knife is engaging in forceful interaction, in agonistic interaction. But his or her action is readily acknowledged to be opposite to that of a person using a knife to injure or kill. Perpetrators of violence are not free of intent and we cannot avoid judging whether actions are harmful.

In this article, the term agonistic is avoided because it does not consider whether an action harms or helps its object and whether an action is intended to harm or help its object. The term aggression is defined as action whose intent is to harm its object and which does harm its object. So defining aggression maintains the distinction that is lost in the term agonism, because aggression does not include action whose intent is to help. The question whether aggressive action is justified or not, is good or bad, remains open. In analysis of national action, it is both necessary and difficult to appraise national aggressive action, but the elemental unit of analysis must be the individual human being. If he or she is not naturally aggressive, then it is hard to conclude that aggression for its own sake is natural to the species.

Aggression covers the action of a person who is attacking another person or an object, whether as an initiated action or as a defense against the attack of another. It only muddles things to say that a person defending him- or herself against another who is bent on homicide is not as aggressive as the attacker. If the defender is successful against the attacker, the defender will survive and the attacker may die. If a nation, say Czechoslovakia, is attacked and occupied in one decade by Nazi Germany and in the next by the Communist Soviet Union, no one save the attacking nation is going to say that Czechs have no right to defend themselves. But, in the historic cases, both Germany and the Soviet Union argued that they were defending their interests against wanton aggression.

In a 1975 resolution the United Nations adopted a definition of aggressive war that specified the invasion of another nation’s territory but avoided the question of harmful intent. While the UN definition avoids the issue of culpability, and so avoids the problem inherent in the term agonism, it leaves indefinite the issue of harmful intent. This indefinition does not help appraise the action of a nation or the UN that intervenes in a domestic dispute within another nation. In the former Yugoslavia, intervention by UN or in the name of the UN remains unappraised and unjustified.

Needs that are innate characteristically are chronically, regularly, satisfied over decades, if not lifetimes. People must always eat. From birth, they have an undying desire for affection. And they develop, early on, a seemingly insatiable desire to be recognized, to be dignified, and to fulfill themselves. Neither infants nor children nor adults like to be ignored or humiliated or denied recognition for doing self-fulfilling work.

There is only consensual rather than objective evidence that the desire to kill, maim, or destroy is innate. People may even be thrilled by it, but the desire seems to pass quickly among at least most people. They admire bravery in others and themselves. They admire the sacrifice that must occur when individuals forsake their private lives, put on uniforms, and learn the skills of killing, but then abandon these desires then they return to civilian life. Except for brief periods, they would rather be doing something else.

A sense of guilt lingers, even when the killing results in vanquishing the enemy. Attempts to suppress guilt and forget the horror of violent conflict – products of very brief personal experience in combat – linger on for years and may never be lost from the unconscious. One seldom feels guilt for eating, for giving and receiving affection, for being dignified, and for creating a poem, writing a story, or fixing a broken chair. One is likely to feel guilt in such circumstances only if he or she realizes that eating deprives another, loving betrays another, or ignoring another may humiliate the person ignored.

It is also evident that aggressive behavior is perhaps always the consequence of the frustration of needs, drives, expectations that quite surely are innate. Even the aggression that occurs within families and neighborhoods involves a previous frustration. A child denied food or affection within its family may in consequence turn violent. A child or young adult as an alienated member of an extra-familial group that is denied recognition may turn violent, as have thousands of individuals who identify themselves as members of a minority and are so identified.

Nations that are enormously ambitious for recognition and power but have been denied these goods may launch very violent wars, as did Germany and Japan in the late 1930s and early 1940s.

But to say that these transitory periods of enormous violence represent an innate human produces a few problems in the explanation. Although it is very common to say that aggressive acts are unprovoked, where are these acts to be found? When a member of a national majority expresses bafflement at the violence of minorities, has he or she satisfactorily determined that nothing is upsetting the minority? He or she might ask a minority member rather than come to conclusions about the innateness of violence. Justifiably or not, people do persuade themselves that their enemy – interpersonal or international – is claiming their lives, their fortunes, and their sacred honor. They do not make these claims when they are threatened by something as relatively minor as not being able to see the sunrise, the cows come home, or the villain in a television program get his or her comeuppance.

Innate, that is, Natural Sources of Tension

Views of human nature have become more complex in this century. In the late eighteenth and nineteenth centuries, notably in the writings of John Locke and Rousseau, two conclusions have, with scant analysis, been attributed to those who heavily emphasize the environment as a determinant of behavior. One is that people are naturally good and get damaged by bad experience. The other is that the mind is pretty much a blank sheet, on which the environment can write pretty much what it wants. That is, Locke, Rousseau, and Marx are credited also with making the moral judgment that it is institutions, both social and political, that are responsible for failing to let human beings achieve what they naturally want to achieve.

Early in the twentieth century, perhaps partly because of the strong, worldwide influence of Marx, environmentalism flourished. Ivan Pavlov did brilliant new work in conditioning responses in dogs, making them drool when they had established a relationship between a bell ringing or a light turning on and the reward of food. This work was elementally consistent with the Marxist assumptions of the revolutionary government after 1917 in Russia and got strong support from the communist regimes. Similar work got established in the United States, first by J. B. Watson, who said that if he were given an infant, he could make out of him virtually any kind of skilled human being – butcher, baker, and candlestick maker.

B. F. Skinner extended the work of Pavlov by getting pigeons to respond to a conditioning stimulus of light or whatever. Extrapolating from pigeons to human beings, he proposed establishing a good society by operant conditioning, which he declared was the responsibility of psychologists. It was not clear whether Skinner was influenced by Plato’s proposal in group l to put the intellectual elite of guardians, but the implication was again clear: that a small group of specialists could manipulate the bulk of humankind in the best interests of both the specialists and humankind.

Heavy emphasis on environment not only frees individuals of responsibility for the existence and the development of institutions. It also produces a dead end in scientific pursuit of understanding: if human nature does not generate needs, demands, expectations, then where do they come from? The problem logically is like that in which Plato and others believing in a supra-human aristocracy have avoided the question as to who guards the guardians. What institutions spontaneously generate what internal tensions in human nature? If people want to eat, what institutions established that natural desire? If people need to get together, be together, and stay together, what institutions generate these social needs? If people want dignity – want to be recognized as distinct beings meriting deference and respect – what institutions elicit or establish that natural desire? Are the needs for food, association, and deference mere excogitations of philosophers, who implant these needs in infants and children but ignore adulthood manifestations of these needs?

Investigators have faced the problem of the content of human nature only partially. Behavioral science for the most part has recognized that human beings share with all other life-forms a desire to be fed and to associate. But behavioral science has shied away from considering that human beings have – at least in larger measure than other life-forms, even other vertebrates – a natural desire for deference and respect or any other nonphysical need, unassociated with the need for food and for sex regarded solely as a means of species perpetuation.

Working mainly with insects, E. O. Wilson established a novel way of looking at behavior. He found that in the interests of perpetuating if not the species, at least the hive, ants were quite willing to sacrifice themselves. Without falling into a trap of saying that human beings should sacrifice themselves to perpetuate the species, Wilson clearly broadened the assumption of many investigators who followed Darwin’s views even more strictly than Darwin did. Wilson said that there was, in addition to the innate desire of individuals to survive, a desire of individuals to participate in making the species survive. Wilson’s frame of reference has evolved in the trend called ‘evolutionary psychology’, whose assumptions include an innate desire to survive but also a desire to associate and to associate amicably.

If progress has been made in conceptualizing human nature, perhaps some consensus exists that human beings are born with more than the desire to survive: that they wish also to associate. Early work in the desire or the trend to associate was elementally addressed by ‘the cat at the U. of Chicago’, who examined not only the tendency of trees to associate but also of a wide variety of animal life. It now seems widely accepted that survival and the social needs are innate.

Other tensions, needs, drives, are less accepted, except perhaps more or less by oversight. A great pioneer in political behavior, Harold Lasswell, posited that there was a natural need for deference and that governments had to address that need. The implications for democratic as distinct from aristocratic or plutocratic government are obvious. And behind Lasswell’s positing of a natural need for deference lie the ‘self-evident’ truths of Jefferson about human beings: that they have a natural right to life, liberty, and the pursuit of happiness. Jefferson’s assumptions have origins in Locke and perhaps in a near-contemporary of Jefferson: Rousseau, whose two principal works, The Social contract and Emile, were published about 15 years before Jefferson composed the Declaration of Independence.

It is this assumption of innate drives beyond self- and species-survival that needs to be addressed directly. It is not possible to say we have one or more useful models of human nature until we have systematically included metasurvival needs. Psychologists since Darwin who have assumed or stated more complex models of human nature have been remarkably neglected, in favor of the more simple, easy-to-conceptualize models of optimistic environmentalists, Locke, Rousseau, Jefferson, Marx, Watson, and Skinner. But the lineage is there.

William James was perhaps the first to systematize a model of human needs that included drives beyond survival. He was followed by Freud, a pessimistic view of innate needs beyond survival. And after Freud came Henry Alexander Murray, who in his Explorations in personality (1938) produced a model of human nature that went beyond both James and Freud to include a long set of mental needs that included the desire not to be degraded (‘infavoidance’), not to be ignored or depreciated. Murray avoided classifying the long list as being innate or involving early conditioning. After Murray, Abraham Maslow developed a rather rigorous set of elemental needs and placed them in a hierarchy. He said that after the physical needs for food, good health, etc., people wanted security, love, self-esteem, and self-actualization – and they wanted them pretty much in that order.

There has been resistance and indifference to the idea of positing some elemental needs that are beyond survival and sex, and resistance to the idea of establishing any priority among elemental needs. Some investigators have acknowledged that human beings have innate physical and love needs, but are not so confident that they also naturally want dignity and freedom to do their thing.

There is some acceptance of the idea that (equal) dignity is innate, but skepticism about its naturalness may be related to the fact that philosophers – including Jefferson – may have called it innate, but not psychologists aside from James, Murray, and Maslow. That is, criticism may derive from the fact that dignity has not been very systematically or deliberately subjected to psychological analysis. Investigators have remained largely constrained by the very dubious assumption that the only innate needs relate to self- and species-survival. An additional argument is that the need for (equal) dignity is generated by – that is, originates in – childhood experience and long-term conditioning to values provided by moralists and religious leaders who have developed institutions that protect equality and that welcome efforts to dignify humankind.

The inescapable problem with environmental determinism which limits innate drives to survival is to explain how metasurvival values got generated in the first place. Have theories of philosophers and moralists emerged spontaneously out of cosmic black holes, without their generators (natural rights theorists like Locke, Rousseau, and Jefferson; and moralists like Buddha, Jesus, and Mahomet) sensing within themselves and people they observed a profound and universal demand?

Such speculations are perhaps unnecessarily argumentative. Rather than continuing a discussion that can be endless, it seems more appropriate to pursue experiments in which determinants that are innate can be more clearly separated from those that are purely products of conditioning or are at least contaminated by it.

Such investigations are possible but they still present problems. If an electrode is implanted in a particular part of the brain where a certain behavior pattern is supposed to generate, is it an innate force if it requires the electrode to be activated? That is, how can an innate force exist if it requires a stimulus to function? One answer to this basic problem in causation is to recognize that there can be no behavior that is not the product of the interaction between the organism and the environment. This is not to say that there are not areas in the brain with rather specific and specialized functions that are innate and have the potential of producing a specific, specialized response.

A look at some experiments undertaken by neurophysiologists will show the progress that has been made in delimiting innate components in the interaction between organism and environment. Some of the research has been reported elsewhere in this encyclopedia but implications of the research merit examination in light of what it says about the innateness of violence.

Some Research in the Neurophysiology of Assertive and Violent Behavior

The unique complexity of the human brain warns us that any findings about it can at best be only partial and tentative. Nonetheless, the complexity need deter us no more than natural scientists are faced with the considerably simpler working of the universe and of elemental, subatomic particles. Astrophysicists and nuclear physicists have progressed enormously on the foundations of Newton, Einstein, and other fundamentalists. We can quite confidently say that time and space are so intertwined that we cannot explain elemental phenomena if we consider them separately. We can say that light travels at a certain speed, but only for practical purposes like establishing just how long is an hour, a day, a century, and a millennium. We can accept as fact that energy has mass, though the difference in mass between energy and more palpable forms of mass like lead or water vapor is truly enormous.

Correlatively, we can say that behaviors like a search for food or affection or for dignity have innate components, without thereby settling the dispute over the innateness of aggression, violence, dominance, or subservience. We have noted that theorists about human nature differ in their belief that violence is innate. Freud, Lorenz, and Ardrey build their basic theses on the assumption that aggression is innate. Other writers, notably Locke, Rousseau, and Jefferson, suppose that it is not. We can get at better bases for addressing the question if we look systematically at the way brain researchers organize their less-certain, less-definitive conclusions about human nature.

The Triune Brain

A physiologist, Paul MacLean, had divided the brain into three basic parts: the reptilian, paleomammalian, and neomammalian. The reptilian part is so named by MacLean because in it are contained behavioral functions that humans share with reptiles. That is, reptiles have been found to manifest these and other behaviors: (1) the establishment and marking of territory; (2) defense of territory; (3) fighting; (4) the formation of groups; (5) the establishment of social hierarchy; (6) courtship; (7) mating; (8) the breeding and sometimes the care of offspring. An anthropocentric view would describe these behaviors of reptiles as humanoid. MacLean’s nomenclature reminds us better of the continuity between the behavior of human beings and those of some of the lowest vertebrates.

Between the most primitive, reptilian part and the most advanced, neomammalian part of the brain (otherwise called the neocortex, the ‘new’ cortex, where information is processed and decisions are made) lies the part which is most critical for our analysis: the limbic system. More than any other part, it is the seat of the emotions.

The limbic system was ‘discovered’ by Paul Broca, in France in 1878. Its major parts are the hypothalamus, amygdala, hippocampus, and the septal area. In reptiles it is most of the brain. In Homo sapiens, it is a much smaller portion and is covered, wrapped around, by the very large neocortex, the thinking and feeling brain.

Following Broca and Papez (1937), MacLean (1972), Delgado (1969), and many others have done extensive research within the limbic system, some of which are discussed here. To the extent that conflict behavior involves emotion, the limbic system is involved, and it is hard to conceive of emotion-free conflict behavior. However, it must always be borne in mind that bundles of nerves connect the limbic system with the neocortex and with the most primitive, ‘reptilian’ parts of the brain.

One implication of these interties is that – physiologically speaking – there are probably few behaviors that are quite free of either the information-processing and decision-making functions of the neocortex or the most primitive ‘instincts’ of the sort that MacLean listed for reptiles. Another implication is that, to the extent that the primitive and the limbic systems ‘dominate’ overt behavior, people may not be totally aware and in control of their reasons for behaving as they do, notably in times of stress.

Research in Nerves

The brain’s activity is so complex and so interactive, both internally and with the environment, that the role of various factors can best be looked at by categories. Neural research is one of two major categories: neural and endocrine. Nerves and hormones interact continuously in the brain and in parts of the rest of the body that are directly under the brain’s control. A pinch or a stab wound may produce an immediate and violent response against the person who pinched or stabbed. This is primarily a neural response. The same stimuli also involve activation of hormonal response: the person pinched or stabbed experiences a surge of noradrenaline or norepinephrine (NE) and adrenaline or epinephrine (E), and this surge may cause the whole organism, the whole person, to respond violently.

The neural part of the brain’s activity does not act alone; neither does the hormonal part. The master, most universally controlling, gland in the brain is the pituitary, the hypophysis. It is the size of a pea. The pituitary is physically divided into a part that is composed of a tiny set of nerves, the neurohypophysis, and another part consisting of a tiny sac of hormones, the adenohypophysis. Functionally, the pituitary’s two separate parts themselves are in continuous interaction.

First, let us examine research whose emphasis has been on nerves. One of the great early investigators was Walter Cannon, who did experiments with dogs, by ablating different parts of the brain or cutting connections between them. He found that when a main trunk of nerves high in the brain (connecting the neocortex with the limbic system) was cut, the animals became veritable engines of destruction, sizing up in a coordinated way whoever was near and waiting for the first opportunity to strike. The neocortex no longer inhibited a response that could be called rage or self-defense. When the cut was made lower, the animals became snarling, growling, uncontrolled, and undangerous animals. That is, the less involved the forebrain, the neocortex, the less controlled was the response behavior.

Electrodes implanted in the brains of various vertebrates have again helped map the paths involved in violence. When electrodes were put in the brainstems (part of the ‘reptilian’ brain) of chickens and an electrical charge was fed into the electrode, the chickens, which previously had been friendly with their human attendants, pecked viciously at them. It is well to note that the chickens were not naturally, normally, hostile but the electrical charge made them so. It served the same function as ablation and cutting in the brains of Cannon’s dogs.

Reis and co-workers in 1973 implanted electrodes in nine gentle cats, in a part of the brain immediately adjacent to the limbic system. When a current of 40 µA was introduced, the cats merely became alert. When it was increased to 50 µA, the cats started to groom them. When it was increased to 60 µA, five of the nine cats started to eat. When the current was increased to 70 µA, seven of the nine cats savagely attacked a rat placed in their cages. When the current was turned off, they stopped their attacks, and when it was turned on again they attacked again.

In 1969, in an experiment with a group of monkeys housed in a single cage, Delgado noted unsurprisingly that the alpha male monkey, the top monkey, was, if not aggressive, at least assertive. He was the first to eat and sat wherever he wanted to. Delgado implanted an electrode in the caudate nucleus, a part of the limbic system, and on the cage wall he put an electrical switch that could send a current to the implanted electrode by remote control. The switch could be operated by any of the monkeys. One of the female monkeys discovered that by pressing the switch, she could stop the alpha’s dominant behavior. After pressing the switch, she could do what no subordinate monkey would dare do to an alpha: she looked him straight in the eye. After the effect had worn off, the alpha male was boss again. There is no evidence that the clever female had read the Declaration of Independence, but clearly she preferred at least equal deference and equal power.

An idiosyncratic case emphasizes the role of the limbic system, the emotional brain, in determining behavior. A mentally healthy attorney started to take offense at offenses that for him became major crises. He got very angry at cocktail parties, pursued and tried to punish drivers who were rude or careless on freeways. He was getting short-tempered with his wife. Persistence and intensity of symptoms led to brain surgery. A tumor surrounded his hypothalamus, a major part of the limbic system. He died in the hospital.

A young woman who had stabbed someone in the heart with a knife was put in hospital. She attacked a nurse with scissors. Brain surgery took the form of cauterizing and thus destroying the amygdala, another major part of the limbic system. It can confidently be said that the behavior of both the attorney and the young woman was violent: at least on the surface, overt evidence indicated conscious attacks on objects these two people considered appropriate. And it cannot be said with any confidence that either the attorney or the girl was responsible for his or her behavior.

There are dozens of hormones – neurochemicals or endocrines – that interact with the nervous system as they control behavior. Their interaction is so reciprocal that one cannot confidently say that nerves control hormonal secretions or vice versa. But there are two categories of hormones that most directly relate to aggressive and violent behavior: the catecholamines and the steroids.

The principal catecholamines relevant to aggressive behavior are NE and E. The sequence of production of these hormones is from dopamine to NE to E. The sequence of production has distinct significance for the kind of behavior each helps produce. Dopamine tends to produce interaction rather basically and positively. Nurses administering dopamine have been the objects of amorous advances from their patients. NE tends to produce broad, unspecified response to protect the organism from threat: ‘destroy that attacker or get me out of here’. E, the metabolite of NE, tends to produce specific, deliberated response: the best way to destroy that attacker is to put him on trial, convict him or her, and then hang him or her.

The ratio of NE varies from species to species. In chickens, lions, and whales, there is more NE than E. In human beings the ratio of NE to E is about 1 to 3. That is, human beings have more of the deliberative kind and other vertebrates more of the generalized kind.

The second category of hormones relating to aggressive behavior is the steroids or sex hormones. The two kinds of steroids are the estrogens and androgens. Both males and females have both kinds: females have more estrogens than androgens and more estrogens than males, who have more androgens than estrogens. Both are metabolites of (are made from) cholesterol. Estrogen is associated with many kinds of behavior, but one of them is nurturance. Androgen is similarly implicated in producing overt behavior, but a principal one is assertive and aggressive behavior.

The production of the steroids increases at puberty and at menopause the proportions change as between males and females. After menopause, women have less estrogen than androgen and have less estrogen than men. One indicator of these changes is that women often have facial hair that they never had before menopause; one indicator in men as they age may get less aggressive and more nurturant. That is, more nurturant than they were – and in some instances more nurturant than women.

It is perhaps more difficult to separate out the behavioral consequences of different catecholamines than, perhaps, to isolate the effect of ingesting too much or too little salt, or too much or too little fatty food. But, without attributing physiological wisdom to the Roman Stoics, with their prescription, ‘nothing to excess’, it does appear that there is a normal range of amounts of catecholamines which, when it is not present, produces abnormal behavior. And that some of this abnormal behavior is clearly assertive and may be aggressive. Furthermore, variation in amounts of catecholamines may be partly under conscious control of the individual human being. And they can take various drugs to control the effect of catecholamines and steroids: among the commonest are alcohol, cocaine, and heroin. People do not need to know the physiology to enjoy or suffer from the effects of drugs on the natural production and effect of hormones.

Research of this kind shows the behavioral consequences of direct intervention in the limbic system. The findings establish physiologically what Freud established psychologically: namely, that unconscious and often uncontrolled forces within human beings are major determinants of behavior. Freud discovered the unconscious origins of adult mental conflict in the (ontogenetic) development of humans as infants and children.

What Broca, Papez, MacLean, and many others have done is to establish the similarities of brain structure and function between humans and lower vertebrates. They thereby have indicated that the emotional and some of the cognitive capacities of humans are phylogenetically rooted in the development of all vertebrate and, perhaps ultimately, all sensate species. Some later research illustrates the point by showing the interaction among neural structures, sex hormones, and various environmental factors in a species of lizard. These combine to produce certain complicated sex behaviors. We can infer that the neural structure of the lizard’s limbic system, its sex hormones, and various environmental factors interact within this reptilian brain in ways comparable to their functioning in human beings.

From Here, Where?

Hitherto in this article, first a definition of human nature that may indicate the area of focus that is appropriate for seeking forces within the human organism that relate to political peace and violence has been offered. Then some research that helps explain political violence has been cited. This kind of research is in its infancy: most relevant research has been evidently undertaken for other purposes than explaining violence. So the relevant fields of political psychology are hard to specify. We are about where Columbus was before he left on his first voyage.

A major obstacle still remains the fact that most social scientists have not considered the need to get familiar with physiology as a step beyond social psychology. Another obstacle is the often scornful rejection of social science by natural scientists. Social science may be about where natural science was before Isaac Newton, but little is gained by arguing the matter. At least social science does not depreciate systematic investigation, however deficient it is in practicing it. But natural science can help enormously if it helps social science become more scientific, not just in its methods but also in the foci of its investigations.

Further Reading

Davies JC. Aggression: Some definition and some physiology. Politics and the Life Sciences. 1967;6(1):27–57.

Dollard JL, Miller NE, Mowrer OH, Sears RR. Frustration and aggression. London: Yale University Press; 1939.

Einstein A, Freud S. Why war?. Paris: International Institute of Intellectual Cooperation; 1933.

MacLean P. The brain in relation to empathy and medical education. Journal of Nervous and Mental Disease. 1972;144:374–382.

Papez JW. A proposed mechanism of emotion. Archives of Neurology and Psychiatry. 1937;38:725–743.

Rackham H. (trans.) Aristotle: Politics. London: Heinemann; 1932.

Skinner BF. Beyond freedom and dignity. New York: A. A. Knopf; 1971.

Von Holst E, von St. Paul U. Von wirkungsgefüge der triebe. Die Naturwissenschften. 1960;18:409–422.

Von Holst E, von St. Paul U. Electrically controlled behavior. Scientific American. 1962;206(3):150–159 (A less complete report of the research originally published in 1960).

Evolutionary Origins and Functions of the Stress Response

R.M. Nesse; S. Bhatnagar; E.A. Young    University of Michigan, Ann Arbor, MI, USA

Utility of the Stress Response

Phylogeny of the Stress Response

How Does the Stress Response Help?

Adaptive Regulation of Stress Responsiveness

Mismatch between Ancestral and Modern Environments

Further Reading

Glossary

Defense   A trait that is latent until aroused by threatening situations in which it is useful.

Natural Selection   The process by which genes that provide a fitness advantage become more common from generation to generation and those that decrease fitness become less common, thus shaping adaptive traits, including defenses.

Phylogeny   The evolutionary history of a trait or a species.

Trade-Offs   The fitness costs and benefits of a trait whose net effects yield a selective advantage.

This article is a revision of the previous edition article by R M Nesse, S Bhatnagar and E A Young, volume 2, pp 79–83, © 2000, Elsevier Inc.

Evolution is the process in which traits such as the capacity for the stress response are shaped by natural selection. Understanding the evolutionary history of a trait, how it gives a selective advantage, and the costs it imposes can help to illuminate its design and regulation and can guide research into its mechanisms and control. The stress response has been shaped by natural selection to increase the ability of organisms to cope with situations that require action or defense. Stress-related mechanisms emerged early in the history of life. Like all traits, they have costs as well as benefits. Because the stress response is so often associated with negative events, its utility has often been neglected. In particular, the release of glucocorticoids, which is often thought to be the hallmark of the stress response, may in fact exist, in part, to protect against other aspects of defensive systems.

Utility of the Stress Response

The vast bulk of research on stress has investigated its causes, mechanisms, and effects. An evolutionary approach instead addresses two very different and relatively neglected questions: (1) How does the stress system give a selective advantage and (2) what is the evolutionary history of the stress system? The answers to these questions provide a foundation in Darwinian medicine for understanding why the stress response is the way it is and why it causes so much suffering and disease. The first and most important contribution of an evolutionary perspective on stress is a clear focus on its utility. The stress system is a complex, sophisticated, and carefully regulated adaptation that has been shaped by natural selection because it gives a selective advantage. That advantage must be substantial in order to outweigh its huge costs. The idea that stress is useful is by no means new. In fact, the very phrase Hans Selye chose to describe it, the general adaptation syndrome, emphasizes its utility. Despite this early emphasis on its benefits, as the idea of stress entered the popular imagination there was a tendency to emphasize its dangers so that the fundamental fact of the utility of the stress response was often forgotten.

Stress and other Defenses

Other defenses are also often confused with the problems they protect against. The capacities for pain, fever, vomiting, cough, and inflammation are often thought of as medical problems, although a moment’s thought reveals that they are useful protective reactions. The ubiquity of the illusion that defenses are abnormalities arises from several sources. First, defenses are often associated with some kind of suffering and therefore seem maladaptive. Unfortunately, however, discomfort is itself probably one aspect of a mechanism that makes it useful. Second, they are reliably associated with disadvantageous situations, so the association bias makes it seem as if they are the problem. Finally, it is possible to use drugs to block the expression of many defenses with very little harm, completing the illusion that defenses are useless. In fact, blocking a defense can be harmful. For instance, suppressing cough in a patient with pneumonia makes it harder to clear the infection and may lead to death, and stopping the diarrhea of a person with a serious intestinal infection may lead to complications. Blocking fever, however, usually has little effect on the speed of recovery from a cold. When blocking a defense is not dangerous, this is because the body has backup protective mechanisms and because the regulation mechanism seems to be set to a hair trigger that expresses the defense at the slightest hint of danger.

Situations in which Stress is Useful

Stress, like fever and pain, is useful only in certain situations. Such traits lie latent until aroused by the particular circumstances in which they are useful. This means that the evolutionary explanation for such traits cannot be summarized in a single function. Instead, the inducible defenses give an advantage by changing multiple aspects of the body that increase its ability to cope effectively with the adaptive challenges that arise in a particular situation. One defense may have many aspects that serve many functions. So, the first step in understanding the adaptive value of stress is not to try to specify its function but to understand the exact situations in which the stress response is useful. To do that, we need to go back to the very origins of complex life forms 600 million years ago. If a very primitive organism had only two states, what are they? The answer is quite straightforward: activity and rest. This is a fundamental divide, one that is maintained even in our biochemical and nervous systems. Biochemical pathways are divided into the catabolic, in which energy is used, and the anabolic, in which energy is stored and tissues are repaired. Parallel to this division are the two arms of the autonomic nervous system. The sympathetic system, which is activated as part of the stress response, increases arousal, blood pressure, heart rate, respiratory rate, and physical activity and institutes other endocrine and physiological changes necessary for action. The other half of the autonomic nervous system, the parasympathetic, inhibits muscular activity, stores energy, and shunts blood to digestion and bodily repair. Is stress, then, the same as arousal for action? Not exactly. As soon as a generic state of arousal was well established, natural selection probably began to differentiate it into subtypes to better meet the demands of different kinds of challenges. Here again, the main bifurcation is quite clear. Arousal is useful in two different situations: threats and opportunities. This division is also represented in our nervous systems. As Gray and others have pointed out, the brain seems to have moderately distinct systems for behavioral inhibition and for reward seeking. The corresponding behaviors are said to be defensive or appetitive and are associated with feelings of fear/pain or pleasure. In psychology, the same division is recognized in the distinct cognitive states promotion versus prevention.

Phylogeny of the Stress Response

Cross-Species Comparisons

Comparisons among different species can help to reconstruct the phylogeny of the stress response. All vertebrates have the proopiomelanocortin (POMC) molecule that gives rise not only to adrenocorticotropic hormone (ACTH) but also to opiate-like peptides. It is intriguing to note that these molecules, with their related functions, are derived from the same parent molecule. All vertebrates also make corticosteroids. Peptide sequences very similar to those of human ACTH are found not only in mammals but also in amphibians and reptiles and even in insects, mollusks, and marine worms. Interestingly they are usually associated with immune cells, equivalent to macrophages, where they set defensive processes in motion. ACTH has long been closely associated with other signaling molecules such as corticotropin releasing hormone (CRH), biogenic amines such as epinephrine and norepinephrine, steroids such as cortisol, cytokines such as interleukin-1, and nitric oxide. All these substances are crucial to defensive systems. The remarkable thing is that genetic sequences for these molecules have not only been conserved over hundreds of millions of years but they continue to serve closely related defensive functions. Why have they changed so little? If a single molecule has several essential functions, this creates a strong selective force against mutations that change the sequence. By contrast, mutations that result in the differentiation of different classes of receptors in target tissues can slowly specialize the responses of that tissue to the signal molecule. And they have, judging from the proliferating classes and subclasses of receptors that are now being discovered.

Cost–Benefit Trade-Offs

Why is the stress system not better? It could provide more effective protection against danger – but only at a still greater cost. Drosophila have been bred to resist the stress of food shortage. After 60 generations of such selection, the new strain is 80% more resistant to starvation. However, the larvae are more likely to die, and development is slowed. Similar results have been found for selection of resistance to other stressors and in other species. Like everything else in the body, stress responses are shaped by trade-offs, sometimes with benefits and costs occurring in different parts of the life cycle.

The mechanisms that regulate the responsiveness of the stress system are shaped by the trade-off between the long-term costs and the immediate benefits of a relatively quick or intense or prolonged stress response. It has been hypothesized that the individuals who are most resilient or resistant to the effects of stress on physiology or behavior are the ones least vulnerable to stress-related diseases. However, are these individuals resilient to all stress-related disorders, or are there situations in which resilience to some disorders means vulnerability to others? The answer is not known, but given the large number of physiological systems affected by stress and/or glucocorticoids, it is unlikely that resilience to one stress-related disorder necessarily protects against all.

Another trade-off reflects the benefits and costs of habituation. For instance, rats exposed to some repeated stressors, particularly those that are mild and cognitive in nature, habituate to that stressor. The hypothalamic-pituitary-adrenal (HPA) response is lower to the nth exposure than to the first exposure. Such habituation seems adaptive for most situations; if the stressor is known and can be easily coped with, then the HPA response should be moderated. Such habituation would, at the very least, conserve resources. However, it would be maladaptive to habituate to stressors that do present some danger. These trade-offs have shaped the brain mechanisms that regulate habituation.

There are interesting sex differences in the habituation of the stress response, with some evidence indicating that habituation occurs in male but not in female rats. Such findings suggest that the selection forces acting on male and female rats may have differed enough to shape distinctly different patterns of habituation. Research is now addressing whether habituation occurs with some stressors in males but with others in females.

Stress responses in adult animals are profoundly affected by early environmental events such as prenatal stress and variations in maternal care. The effects of variations in maternal care are transmitted across generations, with offspring that experience high maternal care exhibiting lower stress responses and providing high maternal care themselves. Such effects seem adaptive in that offspring are likely to experience an environment similar to that of their parents. So, for example, mothers providing low maternal care have high stress responses and so do their offspring when they become adults. However, when cross-fostered to other mothers, the offspring show patterns of stress responsivity similar to that of their foster mother and not their biological mother. Such results suggest that stress responsivity and maternal care are not simply genetically transmitted but are also regulated by early experiences. Such regulation is seen in other mammals and even plants. Some of such transmission across generations may arise from facultative mechanisms that evolved to adjust the system based on early life experiences, and some may arise from more general learning mechanisms.

Difficulties in Defining Stress

The human mind seems wired to try to make neat categories with sharp boundaries, perhaps because we communicate with words and this requires dividing the world up into categories even when that is unnatural. This leads to a tendency to try to make sharp distinctions between different states that may,