Ultimate reasons
This enumeration of motives offered by members of small-scale societies for going to war—women, children, heads, and so on—doesn’t exhaust the list. However, it already suffices to make clear why these named motives by themselves aren’t a satisfying explanation for traditional warfare. Everybody’s neighbors have women, children, heads, and edible bodies, and many or most traditional neighbors have domestic animals, practise sorcery, and can be viewed as bad. Coveting of these individuals and things, or disputes about them, don’t inevitably trigger wars. Even in especially warlike societies, the usual response to a dispute arising is to try to settle it peacefully, e.g., by payment of compensation (Chapter 2). Only if efforts at peaceful resolution fail does the offended party resort to war. Why, then, are compensation negotiations more likely to fail among some peoples than among others? Why are there such differences, when women and the other claimed motives for war are ubiquitous?
The ultimate factors behind a war aren’t necessarily the factors that the participants themselves understand or enunciate at the time. For instance, one theory of Yanomamo warfare debated by anthropologists postulates that its ultimate purpose is to acquire scarce protein by assuring abundant availability of game animals to be hunted. However, traditional Yanomamo don’t know what protein is, and they persist in citing women rather than availability of game animals as their motive for making war. Hence even if the protein theory of Yanomamo warfare were correct (which it probably isn’t), we would never learn about it from the Yanomamo themselves.
Unfortunately, understanding ultimate factors that you can’t ask people about is much more difficult than understanding proximate motives that people can describe to you. Just reflect on our difficulties in establishing the ultimate cause(s) of World War I, despite the availability of enormous quantities of relevant documents to whose study hundreds of historians have devoted their lives. Everyone knows that the proximate cause of World War I was the assassination of Archduke Franz Ferdinand, heir to the throne of the Habsburg Empire, by the Serb nationalist Gavrilo Princip at Sarajevo on June 28, 1914. However, numerous other heads of state and heirs apparent have been assassinated without such dire consequences, so what were the ultimate reasons why this particular assassination did trigger World War I? The debated candidate theories of World War I’s ultimate cause(s) include the pre-war system of alliances, nationalism, threats to the stability of two major multi-ethnic empires (the Habsburg and Ottoman empires), festering territorial disputes over Alsace-Lorraine and transit through the Dardanelles, and Germany’s rising economic power. Because we still can’t agree about the ultimate causes even of World War I, we can’t expect it to be easy to understand the ultimate causes of traditional warfare either. But students of traditional warfare enjoy a big advantage over students of the two world wars, in that we have an almost infinite number of traditional wars to compare.
The ultimate factor most often proposed for traditional warfare is to acquire land or other scarce resources such as fisheries, salt sources, stone quarries, or human labor. Except in harsh fluctuating environments whose conditions keep human populations periodically or permanently low, human groups grow in size to utilize their land and its resources, and can then increase further only at the expense of other groups. Hence societies go to war to seize land or resources belonging to other groups, or to defend their own land and resources that other groups seek to seize. This motive is often proclaimed explicitly by state governments going to war to acquire land and labor. For instance, Hitler wrote and spoke of Germany’s need for Lebensraum (living space to the east), but Russians and other Slavs lived to the east of Germany, so Hitler’s goal of acquiring eastern living space for Germany led him to invade Poland and then Russia in order to conquer, enslave, or kill the Slavs who lived there.
The most extensive test of this theory that land and resource shortages lead to war was by Carol and Melvin Ember, using a cross-cultural sample of 186 societies. From ethnographic information about these societies summarized in the Human Relations Area Files (a large cross-cultural survey), Ember and Ember extracted measures of several causes of resource shortages: the frequencies of famines, of natural disasters such as droughts or frosts, and of food scarcity. It turned out that these measures were the strongest predictor of war’s frequency. The authors took this finding to mean that people go to war to take resources (especially land) from their enemies, and thereby to protect themselves against unpredictable resource scarcity in the future.
Although this interpretation is plausible, it doesn’t operate so straightforwardly that all scholars accept it. While some traditional wars are indeed followed by the losers fleeing and the victors occupying their land, there are also cases of the vacated land being left unoccupied for some time. It is not the case that traditional wars are consistently fiercer in more densely populated areas, because some habitats and subsistence modes can comfortably support much higher population densities than can other habitats and subsistence modes. For instance, hunter-gatherers living at a density of 5 people per square mile in a desert feel more resource-starved and pressed to expand than do farmers living at 100 people per square mile in fertile, warm, well-watered farmlands. That is, what counts is not population density itself, but population density in relation to resource density, resulting in actual or potential resource shortages. If one compares traditional peoples with similar subsistence modes and living in similar habitats with similar resources, the frequency of warfare does increase with population density.
Other ultimate factors proposed to explain traditional warfare are social factors. People may go to war to keep troublesome neighbors at a distance, to get rid of the neighbors altogether, or to acquire a bellicose reputation and thereby to deter the likelihood of attacks by neighbors who wouldn’t hesitate to attack a group with a reputation for not defending itself. This social interpretation isn’t incompatible with the previous theory in terms of land and resources: an ultimate reason for wanting to keep one’s neighbors at a distance may be to maintain secure control of one’s land and resources. But it’s worth mentioning social considerations as a factor separate from resource considerations, because one’s desire to maintain distance from neighbors may cause one to take actions far more extreme than what others would consider necessary just for securing resources.
For example, until around 500 years ago Finland’s population was concentrated on the seacoast and Finland’s forested interior was sparsely inhabited. When individual families and small groups began moving as colonists into the interior, they tried to live as far as possible from each other. Finnish friends told me a story to illustrate how those colonists hated feeling crowded. A man cleared for himself and his family a small farm by a river, pleased that there were no signs of any neighbors. But one day he was horrified to observe a cut log floating down the river. Someone else must be living somewhere upstream! Enraged, the man started walking upstream through unbroken forest to track down the trespasser. On his first day of walking he met no one; on the second day, again no one. At last, on the third day he came to a new clearing, where he found another colonist. He killed that colonist and marched three days back to his own clearing and family, relieved that he had once again secured his family’s privacy. While that story may be apocryphal, it illustrates the social factors that cause small-scale societies to have concerns even about distant “neighbors” far out of sight.
Still other ultimate factors proposed involve benefits, to the individual rather than to the social group, of being warlike. A bellicose individual or war leader is likely to be feared and to gain prestige for his war exploits. That can translate into his being able to win more wives and to rear more children. For instance, the anthropologist Napoleon Chagnon calculated, from Yanomamo genealogies that he gathered, that if one compares Yanomamo men who have or haven’t killed people, the killers have on the average over two and a half times more wives and over three times more children. Of course the killers are also more likely to die or to be killed at an earlier age than are non-killers, but during that shorter lifespan they win more prestige and social rewards and can thereby obtain more wives and rear extra children. Naturally, even if this correlation does apply to the Yanomamo, I’m not recommending it to all you readers, nor can it even be generalized to apply to all traditional societies. In some societies the shorter lifespan of warlike men is likely not to be compensated by an ability to attract more wives per decade of their shorter life. That is the case for Ecuador’s Waorani Indians, who are even more warlike than the Yanomamo. Nevertheless, more zealous Waorani warriors don’t have more wives than do milder men, and they have fewer rather than more children surviving to reproductive age.
Whom do people fight?
Having thus addressed the question why small-scale societies fight, let’s now ask: whom do they fight? For instance, are tribes more likely to go to war against tribes speaking a different language than against speakers of their own language? Do they fight, or do they instead avoid fighting with, tribes with which they trade or
