There are all kinds of problems in posing the question, is war natural? If we conclude it is unnatural, then we are likely to treat it as an aberration that might be avoided if we were to simply know better — that in some sense all wars happen by mistake.

If we conclude that war-making is an intrinsic feature of human nature, then we assume a kind of fatalism that views war as ugly but unavoidable.

In an essay which probes the question of whether humans have the instinct to make war, the evolutionary biologist, David P Barash, makes an important distinction between violence and war — the former being an adaptation, while the latter a capacity. He explains the distinction between adaptation and capacity in this way:

Language is almost certainly an adaptation, something that all normal human beings can do, although the details vary with circumstance. By contrast, reading and writing are capacities, derivative traits that are unlikely to have been directly selected for, but have developed through cultural processes. Similarly, walking and probably running are adaptations; doing cartwheels or handstands are capacities.

Barash writes:

[Napoleon Chagnon’s] best-selling book The Fierce People (1968) [on the Yanomami people of the Venezuelan/Brazilian Amazon] has been especially influential in enshrining an image of tribal humanity as living in a state of ‘chronic warfare’.

Chagnon has been the subject of intense criticism but, to my mind, there is simply no question about the empirical validity and theoretical value of his research. In a field (call it evolutionary psychology or, as I prefer, human sociobiology) that has often been criticised for a relative absence of hard data, his findings, however politically distasteful, have been welcome indeed. Among these, one of the most convincing has been Chagnon’s demonstration that, among the Yanomami, not only is inter-village ‘warfare’ frequent and lethal, but that Yanomami men who have killed other men experience significantly higher reproductive success — evolutionary fitness — than do non-killers. His data, although disputed by other specialists, appear altogether reliable and robust.

So I admire the man, and his work, but I have a growing sense of discomfort about the way that Chagnon’s Yanomami research has been interpreted and the inferences that have been drawn from it.

I fear that many of my colleagues have failed, as previously have I, to distinguish between the relatively straightforward evolutionary roots of human violence and the more complex, multifaceted and politically fraught question of human war. To be blunt, violence is almost certainly deeply entrenched in human nature; warfare, not so much. A fascination with the remarkably clear correlation between Yanomami violence and male fitness has blinded us to the full range of human non-violence, causing us to ignore and undervalue realms of peacemaking in favour of a focus on exciting and attention-grabbing patterns of war-making.

As an evolutionary scientist, I have been enthusiastic about identifying the adaptive significance — the evolutionary imprint — of apparently universal human traits. For a long time, it seemed that Chagnon’s finding of the reproductive success of Yanomami men who were killers was one of the most robust pieces of evidence for this. Now I am not so sure, and this is my mea culpa.

There has also been a tendency among evolutionary thinkers to fix upon certain human groups as uniquely revelatory, not simply because the research about them is robust, but also because their stories are both riveting and consistent with our pre-existing expectations. They are just plain fun to talk about, especially for men.

Remember, too, the journalists’ edict: ‘If it bleeds, it leads.’ You are unlikely to see a newspaper headline announcing that ‘France and Germany Did Not Go To War’, whereas a single lethal episode, anywhere in the world, is readily pounced upon as news. Language conventions speak volumes, too. It is said that the Bedouin have nearly 100 different words for camels, distinguishing between those that are calm, energetic, aggressive, smooth-gaited, or rough, etc. Although we carefully identify a multitude of wars — the Hundred Years War, the Thirty Years War, the American Civil War, the Vietnam War, and so forth — we don’t have a plural form for peace.

It makes evolutionary sense that human beings pay special attention to episodes of violence, whether interpersonal or international: they are matters of life and death, after all. But when serious scientists do the same and, what is more, when they base ‘normative’ conclusions about the human species on what is simply a consequence of their selective attention, we all have a problem.

The most serious problem with Chagnon’s influence on our understanding of human nature is one familiar to many branches of science: generalising from one data set — however intensive — to a wider universe of phenomena. Academic psychologists, for example, are still reeling from a 2010 study by the University of British Columbia which found that the majority of psychological research derives from college students who are ‘Western, Educated, Industrialised, Rich, and Democratic’ — in short, WEIRD. [See “The Weirdest People in the World“.] Similarly, the Yanomami are only one of a large number of very different, tribal human societies. Given the immense diversity of human cultural traditions, any single group of Homo sapiens must be considered profoundly unrepresentative of the species as a whole.

Just as the Yanomami can legitimately be cited as notably violence-prone — at both the individual and group level — many other comparable tribal peoples do not engage in anything remotely resembling warfare. These include the Batek of Malaysia, the Hadza of Tanzania, the Martu of Australia, a half-dozen or more indigenous South Indian forager societies, and numerous others, each of whom are no less human than those regularly trotted out to ‘prove’ our inherent war-proneness.

In the Dark Ages of biology, taxonomists used to identify a ‘type species’ thought to represent each genus, but the idea no longer has any currency in biology. The great evolutionary biologist Ernst Mayr effectively demonstrated that statistical and population thinking trumps the idea of a Platonic concept of ‘types’, independent of the actual diversity of living things, not least Homo sapiens. Yet anthropologists (and biologists, who should know better) seem to have fallen into the trap of seizing upon a few human societies, and generalising them as representative of Homo sapiens as a whole. Regrettably, this tendency to identify ‘type societies’ has been especially acute when it comes to establishing the supposed prevalence of human warfare.

In his justly admired book The Better Angels of our Nature (2011), the evolutionary psychologist Steven Pinker made a powerful case that human violence — interpersonal as well as warring — has diminished substantially in recent times. But in his eagerness to emphasise the ameliorating effects of historically recent social norms, Pinker exaggerated our pre-existing ‘natural’ level of war-proneness, claiming that ‘chronic raiding and feuding characterised life in a state of nature’. The truth is otherwise. As recent studies by the anthropologist Douglas Fry and others have shown, the overwhelmingly predominant way of life for most of our evolutionary history — in fact, pretty much the only one prior to the Neolithic revolution — was that of nomadic hunter-gatherers. And although such people engage in their share of interpersonal violence, warfare in the sense of group-based lethal violence directed at other groups is almost non-existent, having emerged only with early agricultural surpluses and the elaboration of larger-scale, tribal organisation, complete with a warrior ethos and proto-military leadership. [Continue reading…]