Is There a 'War Instinct'?

Introduction: Does human nature incline toward war or peace? What does evolutionary biology say about this? Can the findings of biologists and psychologists be generalized to the entire human species?

The pessimistic view of human nature holds a particular—and indeed paradoxical—allure, a view that has become the firm and unquestioning conviction of many specialists in evolutionary biology. The tendency toward this perspective began long ago. When the Australian-born anthropologist Raymond Dart discovered the first fossil of Australopithecus in 1924, he offered this description of these early hominins: "Certainly given to slaughter; carnivorous creatures who violently seized living prey, bludgeoned them to death, tore apart their broken bodies, dismembered them limb from limb, slaked their thirst with the blood of their victims, and greedily devoured the still-living flesh."

This pessimistic view has a long history, especially in certain branches of Christianity. According to John Calvin, the zealous sixteenth-century French theologian, "The human mind is so completely alienated from the righteousness of God that it conceives, desires, and demands only what is wicked, perverse, abominable, impure, and base. The human heart is so steeped in the poison of sin that nothing but a foul stench can emanate from it."

It is regrettable if some have become convinced of humanity's inescapable sinfulness, sins for which they must pay in the afterlife. But the situation becomes far more serious when people of science and reason also invoke a theory of human nature that threatens to become a self-fulfilling prophecy. For example, the American playwright Robert Ardrey, in his influential book African Genesis (1961), calls humans "children of Cain": "Man is a predatory animal whose natural instinct is to kill with weapons. War and the territorial imperative have shaped the greatest achievements of Western man. Our love of liberty may have sprung from our dreams, but our liberty was won through war and with weapons."

The current that advocates for presenting "war" as one of the defining features of the "human condition" has, in recent decades, moved beyond the purview of anthropologists and evolutionary biologists. The English philosopher Simon Critchley begins his review of John Gray's book The Silence of Animals (2013) in the Los Angeles Review of Books as follows: "Humans do not merely make tools of killing. We are killer apes. We are foul, aggressive, violent, and rapacious hominins."

On the other hand, we have the American anthropologist Napoleon Chagnon, who spent decades researching and studying the Yanomami people in the Amazon region of Venezuela and Brazil. His bestselling book, Yanomamö: The Fierce People (1968), had a remarkable impact in solidifying our image of tribal peoples as individuals perpetually engaged in "intense warfare and combat."

Chagnon's book has been heavily criticized, but, in my opinion, the empirical validity and theoretical value of his research and studies remain intact. In a field (evolutionary psychology or, as I would term it, human sociobiology) that has often been criticized for a lack of concrete data, Chagnon's findings, however disrespectful they may seem, hold great value and importance. Among Chagnon's findings, one of his most compelling is that not only were there frequent and lethal conflicts between different Yanomami tribes, but that Yanomami men who committed killings had significantly greater evolutionary fitness and reproductive success compared to those who did not. The data Chagnon provides, although contested by other specialists, appear on the whole to be reliable and robust.

So I admire Chagnon and his work, but I view the manner of interpreting his research on the Yanomamö and the conclusions drawn from it with ever-increasing skepticism. What troubles me is that many of my colleagues, as I said earlier, have been unable to distinguish between the evolutionary and relatively straightforward roots of “human violence” and the more complex, multi-layered, and political problem of “human warfare.” To put it bluntly, violence very likely has deep roots in human nature; war and battle, however, do not. Excessive focus on the quite obvious link between Yanomamö violence and male evolutionary fitness has prevented us from attending to the diverse spectrum of human non-violence, and has led us to ignore peacemaking and conciliation in order to concentrate on the exciting and attention-grabbing patterns of war-making.

As a specialist in evolutionary biology, I have had a great eagerness to acknowledge the hereditary implications or evolutionary signatures of human traits (characteristics that are seemingly universal and widespread). For a long time, I believed that Chagnon’s findings regarding the high reproductive success of Yanomamö men who were killers were among the most robust evidence presented to prove this point. Currently, however, I am not so sure about this, and this must be chalked up to my admission of error.

There is a tendency among anthropologists and evolutionary biologists to regard certain human societies as unparalleled sources of inspiration and discovery, not merely because the research and studies conducted on them have been rich and extensive, but also because the circumstances of these societies align perfectly with our pre-existing expectations. Engaging with their stories is enjoyable and entertaining, especially for men.

Recall the journalists' and reporters' adage: “If it bleeds, it leads.” It seems unlikely that a newspaper's main headline would be “France and Germany Did Not Go to War with Each Other,” whereas the smallest deadly scene, anywhere in the world, easily makes top news. Linguistic conventions also attest to this. It is said that Bedouins have nearly a hundred different words for camel, and with their help distinguish between types of calm, restless, ill-tempered, tame, rough, etc., camels. But, while we have diverse expressions to refer to “wars”—the Hundred Years' War, the Thirty Years' War, the American Civil War, the Vietnam War, and the like—we use “peace” merely in an abstract and singular form and have no different words to refer to its types.

From an evolutionary perspective, humans seem to pay special attention to violent events, whether between individuals or between nations: wars, on the whole, are matters of life and death. But such an approach by scientists and specialists and, more importantly, their action of basing their “normative” anthropological conclusions on what was merely the result of their own selective attention, is truly problematic.

The most serious problem seen in Chagnon's views and their influence on our understanding of human nature is a problem observable in many branches of science: generalizing a set of findings—however convincing—to a much wider world of phenomena. For example, academic psychologists are still grappling with the consequences of research conducted in 2010 at the University of British Columbia, which showed that the majority of psychological research is carried out by students from “Western, Educated, Industrialized, Rich, and Democratic” countries. Now, one must consider that the Yanomamö are only one sample among tribal human societies, societies that are enormously diverse. Given the immense diversity of human cultural traditions, no single group of Homo sapiens can truly be considered representative of the entire human species.

The Yanomami can rightly be considered highly violent—both at the individual and the group level; however, many other tribal societies have nothing to do with quasi-warfare violence at all. The Batek tribes in Malaysia, the Hadza in Tanzania, the Martu in Australia, numerous nomadic tribes in the southern Indian subcontinent, and many other tribes are like this, and this is despite the fact that they are just as "human" as the tribes cited as proof of innate human bellicosity.

In an era when biology had not yet flourished, taxonomists considered "type specimens" to represent the characteristics of a species, but this practice is no longer common in modern biology. Ernst Mayr, the eminent evolutionary biologist, rightly demonstrated that typological thinking has a Platonic conception of the concept of "type," a conception that ignores the real diversity of living organisms, and even the diversity of Homo sapiens. Nevertheless, it seems that anthropologists (and biologists, despite their greater awareness) have fallen into the trap of considering a few human societies and generalizing them as representatives of the entire human species and all sensible humans. It is regrettable that this tendency to identify and promote "type societies" intensifies in discussions of the dominance of warfare over the human condition.

Steven Pinker, an evolutionary psychologist, in The Better Angels of Our Nature (2011), a rightly admired book, demonstrates with striking evidence that human violence—both interpersonal violence and warfare—has sharply declined in recent periods. However, in order to emphasize the positive and improving aspects of social norms in recent times, Pinker exaggerates the "natural," "innate," and pre-existing level of our bellicosity, claiming that "chronic raiding and feuding characterize life in a state of nature." The truth, however, is the opposite. As recent studies by anthropologist Douglas Fry and others have shown, the most widespread mode of life for much of our evolutionary history (especially in the pre-Neolithic era) was nomadic hunter-gatherer existence. In this mode of life, humans certainly engaged in interpersonal violence, but warfare in the sense of lethal violence by one group against other groups was virtually non-existent, and only emerged with the increase in agricultural products and the development of large-scale tribal organizations, growing alongside martial spirits and military leadership in its early form.

Some other admired scientists have similarly gone astray. Biologist Edward O. Wilson, in The Social Conquest of Earth (2012), calls warfare "humanity's hereditary curse." I admire Pinker's and Wilson's aversion to war, but I wish they had thought more deeply and considered the archaeological and cross-cultural evidence more carefully before joining the "war has always been with us" bandwagon.

Human history shows that warfare is a recent phenomenon in our evolutionary history. But what about our closest relatives, the apes? We have no living ancestor among the apes; we undoubtedly share a common ancestor with chimpanzees, bonobos, gorillas, orangutans, and gibbons, but the social behavior of the latter three species differs markedly from that of modern humans, while chimpanzees and bonobos exhibit almost opposite behaviors. Chimpanzees are renowned for engaging in violent, group-level confrontations, as well as acts of search-and-destroy, reminiscent of human skirmishes and warfare. Conversely, bonobos—who share the same evolutionary distance from Homo sapiens—show no such behavior at all and are famous for "making love, not war."

When it comes to belligerence, violence, and war-mongering, no straightforward, single thread runs through our evolutionary history. On the one hand, we are capable of committing horrific and heinous acts of violence; on the other, we display remarkable compassion and self-sacrifice. Our selfish genes drive us toward vile, destructive, and unpleasant deeds; and yet, these same selfish genes also urge us toward boundless selflessness and altruism. It is at least possible that the very rapid evolution of our brain was a product of our success in warlike competition with other groups of primitive humans and hominids. But it is equally possible that such evolution was a product of our cooperation, coordination, and mutual care.

In fact, it is not difficult to devise models according to which animals and humans skilled in these behaviors (with genes that predispose such tendencies) would have a greater chance of survival through natural selection compared to other individuals and genes more inclined toward belligerence. Moreover, while warfare is a recent phenomenon in human experience and its foundation is therefore more cultural than natural, systems of behavioral self-restraint have long been established, are seen among countless animal species, and thus likely have deep roots in our nature. On the whole, even in today's war-torn world, wars are actually far less common than non-violent compromises; such compromises occur daily, both between individuals and between nations.

I have never claimed, nor do I claim now, that humans are biologically identical in their capabilities and inclinations and can—independent of their evolutionary heritage—do whatever they wish and become whomever they want. We can never be as altruistic as worker bees, or as solitary as the deep-sea anglerfish. No human society exists whose members copulate multiple times daily, or never engage in it at all. But our developmental tendencies also have limits—and note, this is coming from an evolutionary biologist who is accused of holding genes responsible for all our doings.

A distinction must be made between adaptations and capacities along the evolutionary path. Language is almost certainly an adaptation, a product of compromise, something all normal humans are capable of acquiring, though they do so in different ways under different conditions. In contrast, reading and writing are considered capacities, that is, derivative traits in which natural selection likely played little role and which developed through cultural processes. Similarly, walking and probably running are adaptations; chariot-racing and tightrope-walking are capacities. In my view, violence between individuals is a kind of human adaptation, not unlike sexual activity, parental care, communicating with others, and the like. It is something I see in all human societies. At the same time, war (which is historically recent, and enormously diverse in its geographical scope and details) is almost certainly a capacity. And capacities are neither universal nor obligatory.

Let me be clear. Violence is common and, unfortunately, deeply human, just as the recourse to violence under certain conditions is inherent in the nature of many other animals. But war is another matter. Warfare is a kind of capability, and it requires deadly violence at the group level. Hence, it is fitting to distinguish between war and rivalry, anger, revenge, and various types of homicide. Consider this perhaps not entirely apt analogy. Violence is like a marriage ceremony, given the process by which mature adults formalize their relationship, a relationship that appears to be universal and beyond cultural boundaries, and can probably be counted among the adaptive components of human nature. War, on the other hand, is like an engagement party or a pre-wedding celebration, in a hotel ballroom, with dancing, music, and an elaborate reception. One can rule that photographing the ceremony, the multi-tiered cake, lining up the bridesmaids, the special car for the bride and groom, and the like do not originate from the human genetic structure, even though humans are capable of providing such things. Similarly, overt and long-standing violence among humans is a reality and, however regrettable, is part of human nature and disposition. War is even more regrettable, but it is no more 'natural' or innate than an engagement party or a bomber aircraft assembly line.

The psychologist B. F. Skinner wrote, 'No theory can change what it is about; man remains what he has always been.' This holds true for most phenomena: the solar system is the same one about which Ptolemy had mistaken ideas; and it did not change after the theories of Copernicus, Kepler, and Galileo were presented, theories that offered a more accurate description.

But theories about human nature are somewhat different. When I write or speak about the social behavior and reproductive strategies of various species of mountain viscachas, my words and writings have no socio-political consequences. But when I write or speak about violence, aggression, and/or warfare among humans, my words and writings (whether about the peace-loving Lepcha of the Himalayas or the fiercely violent Yanomami) have enormous consequences.

The issue is not that a theory can change human nature itself. The issue is our expectations and therefore our behavioral changes, and their serious consequences. For example, if we are convinced that Thomas Hobbes was right and that humans are naturally inclined toward baseness and brutality, this belief will have consequences for our political views, including our perception of national priorities in budgeting (for instance, how much to invest in education and health versus military and law enforcement forces), and this, in turn, can become a kind of self-fulfilling prophecy. Are arms races and cycles of distrust between nations not the result of considering the other side as aggressive, potentially violent, and undoubtedly belligerent, and does this not, in turn, lead to policies and confrontations that prove the reality of such assumptions?

Theories about fundamental human nature, when they touch upon the subject of war and peace, become more serious and consequential than any other evolutionary inquiry (inquiries, for example, into whether modern humans share the same genes as Neanderthals, and the like). The issue is not that I believe in a postmodern world where language and ideology shape 'reality.' The issue is that I believe some ideas have real effects on important matters such as the level of budget allocation to defense and the waging or not waging of war.

I am not saying that scientific views should be evaluated according to their ideological, political, and social consequences. Unlike matters pertaining to ideology, theology, and ethics, science should be evaluated solely on the basis of its falsifiability, the usefulness of its fruits, and the extent to which it generates testable ideas. But we must also be wary of the dangers of misusing science for ideological ends; not to mention that some researchers may, unwittingly and merely through their choice of study subjects, introduce bias into their studies and research—especially when they take one or a few human societies as representative of the entire human species. The situation becomes even more precarious when the issue goes beyond “purely scientific” errors and has consequences for social and political decisions.

The human mind gravitates toward simple either/or propositions (either God or the Devil, either the cowboys or the Indians, either with us or with the terrorists), but reality is subtler and more complex. This is especially true of the seemingly simple question of whether humans are “by nature” and “instinctively” aggressive and violent. In the past, the common conception of humans as “killer apes” was clearly misguided due to its one-dimensionality; likewise, others sought to prove that we humans are all cooperative and peace-loving. Our human nature is neither Rousseauian nor Hobbesian; both good and bad angels sit on our shoulders, and our evolutionary inclination can go either way.

Now, readers who take evolution as their intellectual guide may well be stunned and disappointed to encounter the fact that our hereditary endowment is so ambiguous and equivocal. It is certainly important to examine the evolutionary background of our tendencies, but any answer brings us back to Jean-Paul Sartre’s statement that humans are “condemned to be free.” It may be a comfort to pacifists that we are not biologically condemned to warfare, and peace-lovers may be disappointed that we are not entirely inclined toward peace, but our task is to assess our distinctively human condition as honestly and candidly as possible.

When confronting issues of belligerence or peacefulness, it is far better (not only for the accuracy of scientific research but also for its social consequences) to take seriously the dictum of that expert on human nature, Theodor Geisel: “You have brains in your head. You have feet in your shoes. You can steer yourself any direction you choose.”

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Is There a “War Instinct”?

Translation: Nima Panahandeh

This article is a translation of the following work:

David P. Barash (2013) Is there a War Instinct?

David P. Barash is an evolutionary biologist and professor of psychology and biology at the University of Washington.

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