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War & Peace

Are Human Beings Naturally Violent And Warlike?

David P. Barash says, not necessarily.

Ideas have consequences. Few people – and probably no philosophers – would disagree with this. It is also unarguably true that not all ideas are equally consequential. In my opinion, amongst the most important ideas are those surrounding questions of ‘human nature’, especially the questions whether human beings are innately violent or naturally predisposed to war. If we are, and if violence and war are therefore inevitable, then efforts toward peace would appear futile, and we should all resign ourselves to a Hobbesian “warre of every man against every man” (Leviathan, 1651) along with the martial necessities this implies, including swollen military budgets, diminished resources for domestic policies, a presumption of international enmity, and so forth.

Questionable Interpretations

In his book Beyond Freedom and Dignity (1971), psychologist B. F. Skinner wrote that “no theory changes what it is a theory about. Man remains what he has always been.” This is certainly true with respect to our knowledge of the physical world. Before Copernicus, Galileo and Kepler, although many serious thinkers believed the Ptolemaic model of a geocentric universe, their error did not alter the astrodynamics of the solar system, which was then and has continued to be heliocentric, regardless of what theories people have had about it. Similarly for gravity before and after Newton, space-time before and after Einstein, and so forth.

Strictly speaking, the same applies to theories of human nature too: peoples’ instincts, including the ostensible ‘instinct’ for violence, will remain whatever they are regardless of what we think about them. But concerning such matters the connection between expectation and reality becomes complex, because of the risk that theories of human nature feed directly into people being liable to modify their behavior (although not their ‘nature’) as a result. Consider for instance militarists in country A, who are convinced that inhabitants of country B are caught in the grip of an unshakeable instinct-driven warproneness. As a result, A refuses to engage in serious negotiations, preferring to arm itself. Observing A’s actions, and equally convinced that A is inhabited by people with an irrevocable proclivity for war, the leaders of B do the same. Each side points to the other as justifying its own bellicosity, at the same time confirming their often unspoken assumption that war is both natural and inevitable. The danger, in short, of assuming that Homo sapiens has a natural instinct for war is that it can become a highly destructive self-fulfilling prophecy, not only closing off possible avenues of peaceful conflict resolution, but actually making war more likely.

Nonetheless, a purportedly scientific view of anything – humanity’s presumed instinct for warfare included – must stand or fall not on its social and political consequences but on its scientific credentials. And here, the ‘war is in our genes’ perspective is not only scientifically invalid but ethically suspect.

The late Carl Sagan famously pointed out that extraordinary claims require extraordinary evidence. I believe that we should extend this dictum to say that claims with potentially destructive social consequences also require extraordinary evidence. This makes it especially regrettable that a substantial current of recent academic writing – much of it given the apparent imprimatur of evolutionary science – has suggested that Homo sapiens is inherently violent and warlike. Last year, for example, an article in The National Interest entitled ‘What Our Primate Relatives Say About War’ answered the question ‘Why war?’ with ‘Because we are human’. At about the same time, a piece in New Scientist asserted that warfare has “played an integral part in our evolution,” and a research report in the journal Science claimed that “death in warfare is so common in hunter-gatherer societies that it was an important evolutionary pressure on early Homo sapiens.”



Cain Kills Abel by Bartolomeo Manfredi

Nothing new here, except that the claims are somewhat less lurid than those of the recent past. For instance, anthropologist Raymond Dart, who discovered the first australopithecine fossil in 1924, wasn’t shy about concluding that these early hominids were “Confirmed killers: carnivorous creatures that seized living quarries by violence, battered them to death, tore apart their broken bodies, dismembered them limb from limb, slaking their ravenous thirst with the hot blood of the victims and greedily devouring living writhing flesh.” In his widely read book, African Genesis (1961), playwright Robert Ardrey picked up Dart’s pointed perspective when he announced that “We are Cain’s children… Man is a predator whose natural instinct is to kill with a weapon. It is war and the instinct for territory that has led to the great accomplishments of Western Man. Dreams may have inspired our love of freedom, but only war and weapons have made it ours.”

Most influential, I suspect, has been the research of anthropologist Napoleon Chagnon, whose decades-long study of the ‘fierce’ Yanomamo people of the Amazon rainforest has been widely interpreted as proving that if you scratch the superficial surface of civilization, human beings will be revealed to be natural born killers.

I know Professor Chagnon, and have great respect for his courage – intellectual as well as physical – and high regard for his science; I am also convinced that he has been grossly abused by much of the anthropological establishment, by being accused of misdeeds of which he was entirely innocent – in large part because his findings that the Yanomamo are belligerent and warlike went against the ideological preferences of many of his colleagues. (Herein lies an important tale, fit perhaps for another account: the extent to which personal politics often enters into the question of whether human beings are inherently violent.) In any event, after considerable controversy, Chagnon’s research has been widely accepted – perhaps too widely; or rather, I suspect it has been over-generalized. Thus, many biologists and more than a few social scientists have extrapolated from the Yanomamo to Homo sapiens generally, arguing that what holds for the former is therefore true for the latter as well. It is remarkable that otherwise accomplished scholars should make such a beginner’s error, equivalent to seeing a mallard drake and concluding that all ducks have iridescent green heads. The Yanomamo are indeed quite violent; but many other neolithic groups are not, including the Batek of Malaysia, the Hadza of Tanzania, the Mardu of Australia, a half-dozen or more indigenous South Indian forager societies, and numerous others, each of which are no less human than the Yanomamo, who are regularly trotted out to ‘prove’ our inherent warlikeness. But of course, there is no basis for assuming that the Yanomamo are somehow more indicative of a ‘natural human condition’ than are the others.

A similar logical error is regularly made when it comes to extrapolating innate human violence from the observed behavior of a limited number of nonhuman primate species. Savannah baboons from East Africa were among the first free-living nonhuman primates to be studied, and, just by chance, they are also among the most aggressive and violent. Similarly, Jane Goodall’s path-breaking research on free-living chimpanzees eventually revealed that these animals, too, are predisposed to substantial intergroup violence, involving raiding activities analogous in many ways to human warfare. Not surprisingly, this research has led to the generalization that human beings have inherited the baboon and chimp proclivity for group-oriented violence, not only analogous to warfare, but presumably homologous to it.

There are, however, several major problems with this presumption. For one, human beings did not evolve from either baboons or chimps. Neither species is ancestral to Homo sapiens; rather, we share common ancestors with both. Moreover, there are other nonhuman primates, including mountain and lowland gorillas, as well as bonobos (previously called pygmy chimpanzees) that are notably nonviolent; and bonobos are no less closely related to human beings than are chimpanzees. Choosing either species as a model for natural human behavior says more about the ideology of the person doing the choosing than about the biology of human beings. (It is worth noting therefore that just as warprone chimpanzees are regularly referenced by the ‘war-is-natural’ crowd, bonobos appear as a predictable trope employed by those commentators who prefer ‘make-love-not-war’ as the default human predisposition.)

The role of predation on other species in forming the human psyche is similarly an open question. (Chimpanzees occasionally hunt and kill other primates; bonobos do not.) Some anthropologists emphasize the formative influence of ‘man the hunter’ while others argue that ‘woman the gatherer’ prehistorically provided substantially more calories, and thus generated more influence upon our early evolution. Either way, it is important to distinguish between interspecies predation and intraspecies aggression. Although the former is certainly violent, predatory species such as for example lions employ entirely different behavior patterns when obtaining their prey compared to when engaging in violent competition with other lions.



Allegory of Peace and Justice by Corrado Giaquinto, 1754

Ambiguous Tendencies

What, then, is the biological state of Homo sapiens when it comes to violence and war? Unfortunately for those who like their answers simple, reality is ambiguous, or rather, ambidextrous, in that it tends to point in two conflicting directions. Our species is certainly capable of violence at both the individual level (e.g., assault, rape, homicide) as well as at the group level (war). But a capacity is a far cry from a necessity – which would imply a predisposition simmering just below the surface, urgently seeking opportunities to burst out. Yet there is no evidence whatever that human beings who have lived a consistently nonviolent life eventually feel an need to commit mayhem at the behest of their frustrated genes. By the same token, there is abundant evidence that at the level of societies, people are quite capable of renouncing war, since numerous societies have done just this.

Nonetheless, it is equally evident that natural selection has equipped our species with a predilection for violence under certain circumstances. These include situations in which resource competition is high: for food, mates, territory, for example; and under a variety of other social conditions – for example when issues of social status are sufficiently intense. An identifiable subset of humanity – young adult males – is especially vulnerable to such pressures. Moreover, it must be emphasized that whereas interpersonal violence is directly associated with relatively simple neurobiological influences, involving readily identifiable brain regions such as the limbic system, and particular transmitter hormones, war is a quite different phenomenon, typically involving elaborate cognitive processes, extensive planning, and (ironically, perhaps) substantial social cooperation, at least among those on the same side.

Although there is substantial reason to believe that natural selection has directly equipped human beings with mechanisms that readily lead to individual violence, there is no evidence that warfare as such has been part of the biological bequeathal to us as hominids. On the contrary, there is abundant evidence that war is a comparatively recent cultural addition to the human repertoire, acquired within the last 10,000 years or so as a result of several factors, including the invention of agriculture – resulting in the accumulation of valuable material resources that lend themselves to being stolen as well as defended, along with enabling the construction of elaborate social hierarchies – plus increasingly effective technologies for communication, coordination and killing. (The evidence for the recent emergence of war is persuasively reviewed and summarized in War, Peace, and Human Nature: The Convergence of Evolutionary and Cultural Views (2013), edited by anthropologist Douglas P. Fry.)

Even as human evolution has permitted and in some cases even encouraged the elaboration of violent behaviors, it has also promoted constructive social activities and inclinations, including, but not limited to, altruism, empathy, and numerous aspects of social coordination for learning, handicrafts and tool-making, constructing homes, animal enclosures, food storage systems, crop-raising, as well as animal domestication, organizing daily as well as migratory movements of people, and so forth. An increasingly viable hypothesis identifies the elaborate intellectual prerequisites for success in a highly social and co-operative species such as ours as having exerted substantial selection pressure leading to the evolution of the uniquely high level of human intelligence. At the same time, such high intelligence has also set the stage for developing more elaborate techniques of warfare. After all, the invention of nuclear weapons is itself a triumph of the human intellect, as well as an ironic manifestation of our capacity for cooperation.

In short, when it comes to violence and war, evolution’s bequeathal to Homo sapiens is best symbolized by the two-faced Roman god Janus, who represented the first month of each year because he looks backward to the year just finished as well as forward to the one that is beginning. Similarly, our Janus-faced biological heritage can predispose human beings toward either violence or peace, depending on the circumstances. And despite being an evolutionary biologist myself, I am also enough of an optimist as well as a believer in the power of human cultural self-direction to espouse not only the desirability of peace but also its feasibility. A prerequisite, however, is that people free themselves from the cynical, self-deceiving, and indeed scientifically unsupportable presumption that our species is biologically doomed to unceasing violence.

There is a story, said to be of Cherokee origin, that speaks to this matter, and to our shared responsibility. A young girl was troubled by a recurring dream in which two wolves fought viciously with each other. When she recounted the dream to her grandfather, a village elder renowned for his wisdom, he explained that there are two wolves inside everyone, one peaceful and the other warlike. At this, the girl was even more upset, and asked which one wins. Her grandfather’s response: “The one you feed.”

© Prof David P. Barash 2014

David P. Barash is an evolutionary biologist and professor of psychology at the University of Washington, whose most recent book is Buddhist Biology: Ancient Eastern Wisdom Meets Modern Western Science (2014, Oxford University Press).