War: What Is It Good For? (A Brief History of Humankind)

If we think how many things besides frontiers of states the wars of history have decided, we must feel some respectful awe, in spite of all the horrors. Our actual civilization, good and bad alike, has had past wars for its determining condition.

—William James

Ah, Tahiti. The lush island whose carefree natives the painter Paul Gauguin used as icons of primitive bliss. The serene culture which Jean-Jacques Rousseau considered evidence that humans had been "noble savages," peaceful and benign, before their corruption by civilization. Unfortunately, as the anthropologist Lawrence Keeley has noted, Rousseau relied for this conclusion on reports of Tahiti that omitted relevant parts of its history. For example: the custom in which a victorious warrior would "pound his vanquished foe’s corpse flat with his heavy war club, cut a slit through the well-crushed victim, and don him as a trophy poncho."

Time and again there have been reports of a truly peaceful primitive people. Almost always, the reports have not worn well. Remember the "gentle Tasaday," the isolated band of hunter-gatherers discovered in the Philippines in the early 1970s—the people who had no word for "war"? Their authenticity fell into doubt along with the credibility of their discoverer, Manuel Elizalde. As the New York Times would later note, "It did not help when members of a neighboring tribe said Mr. Elizalde had paid them to take off their clothes and pose as Tasadays for visiting journalists."

To be sure, there are hunter-gatherer societies that don’t exhibit the elaborately organized violence denoted by the term "war." But often what turns out to be lacking is the organization, not the violence. The warless !Kung San were billed in the title of one topic as The Harmless People, yet during the 1950s and 1960s, their homicide rate was between 20 and 80 times as high as that found in industrialized nations. Eskimos, to judge by popular accounts, are all cuddliness and generosity. Yet early this century, after westerners first made contact with a fifteen-family Eskimo village, they found that every adult male had been involved in a homicide.

One reason the !Kung and most Eskimo haven’t waged war is their habitat. With population sparse, friction is low. But when densely settled along fertile ground, hunter-gatherers have warred lavishly. The Ainu of Japan built hilltop fortresses and, when raiding a neighboring village, wore leather armor and carried hardwood clubs. The main purpose of the raids—to kill men, steal women, and settle grievances, real or imagined— is a time-honored goal of primitive warfare. Even today it is part of life among the Yanomamo of South America.

The behavior of observed Stone Age peoples is hardly the only evidence that the Stone Age was a bloody time. In a cave in Germany, cluster of skulls more than 5,000 years old were found arrayed, as one observer put it, "like eggs in a basket." Most of the thirty-four victims had been knocked in the head with stone axes before decapitation.

Anyone hoping that cultural evolution always translates into moral improvement will be disappointed to hear that such evidence of violent death is especially common among remains of the more complex hunter-gatherer societies. And in the yet-more-complex agrarian societies on the ethnographic record, things are similarly grim. In south Asia, a young Naga warrior was not considered marriageable until he had brought home a scalp or a skull. In Borneo, a Dayak hero returning from war would be seated in a place of honor and surrounded by singing women, with the head of one his victims placed nearby on a decorative brass tray. The warrior of Fiji gave their favorite weapons terms of endearment; one war club was called "Damaging beyond hope," and a spear was dubbed "The priest is too late."

All of this forces us to confront the fact that, as Keeley has put it, "what transpired before the evolution of civilized states was often unpleasantly bellicose." Human violence has been around a long time, and often it has been not man against man, but group against group. Ever since the early stages of cultural evolution—the era of hunter-gatherer societies—that evolution has been shaped by armed conflict.


This would seem to throw a wrench into the analytical works. So far this topic has mainly stressed the forces of human cooperation, the win-win situations. The thesis has been that the direction of history results largely from the playing of non-zero-sum games. But, presumably, once someone has decided that he wants to use your corpse a a poncho, the two of you are playing a zero-sum-game; his gain is your loss. So too with warring villages. When men from one village raid the other, kill the men and abduct the women, the air is rife with zero-sumness. And so on, up the ladder of cultural evolution: whether the contestants are villages, city-states, whatever—war is hardly non-zero-sumness incarnate.

Still, war isn’t nonstop zero-sumness, either. One big reason is that, even as war is inserting zero-sum dynamics between two groups, within the groups things are quite different. If your village is beset by axe-wielding men bent on slaughter, your relations with fellow villagers can pivot quickly toward the non-zero-sum; acting in concert you may fend off the assault, but divided you will likely fall.

Much the same interdependence exists among the axe-wielding slaughterers; in unison lies their best hope for victory. So, whatever side you’re on, you and your fellow villagers are to some extent in the same boat; your fate is partly shared. That, actually, is a good rough-and-ready index of non-zero-sumness: the extent to which fates are shared. War, by making fates more shared, by manufacturing non-zero-sumness, accelerates the evolution of culture toward deeper and vaster social complexity.

This was a constant refrain of one early cultural evolutionist, the sociologist Herbert Spencer. He overdid it ("Only by imperative need for combination in war were primitive men led into cooperation"), but he was on to something.

Consider again the Northwest Coast Indians. We’ve already seen how their evolving technology of sustenance raised social complexity. Division of labor and capital investment grew, and leadership emerged in the form of the "Big Man," who handled the logistics and helped keep social life in harmony. But all of this heartwarming cooperation to harvest nature’s bounty was not the only social cement, nor the only cause for the Big Man’s authority. War among the various peoples along the Northwest Coast was a chronic threat. Just look at their technology—not the fishhooks and salmon traps, but the daggers, battleaxes, war clubs, and bone-head spear ; the stockades, wooden helmets, and coats of armor made of leather and wooden slats.

Aggression was a way to obtain land or slaves or women, or just to do some quick plundering. (The Haida of the Queen Charlotte Islands have been called the Vikings of the Northwest Coast.) But whatever the cause of war, being on the losing end was bad news. So being tightly knit was a good idea, as was having a leader. Someone has to guide the peacetime amassing of military technology. And, as Spencer observed, war, "requiring prompt combination in the actions of parts, necessitates subordination. Societies in which there is little subordination disappear." Again and again, societies have chosen subordination over disappearance. Faced with war, they fall in line. Walter Bagehot, one of Spencer’s contemporaries (and an early editor of The Economist), explained the consequent social harmony this way: "the tamest are the strongest."

That zero-sumness promotes non-zero-sumness hould come as no surprise. The standard example of non-zero-sum dynamics, after all, is the game-theory exercise called "the prisoner’s dilemma." If two partner in crime cooperate—if each agrees to stay mum when interrogated by the prosecutor, rather than implicate the partner in exchange for lenient treatment—both can benefit. And the source of their common interest is the conflict of interest between them and the prosecutor.

In the realm of primitive warfare, this unifying effect can go beyond the people of a single village. One great way for a village to fend off assault, or to conduct assault, is to ally with another village, a standard tactic among the Northwest Coast Indians. And, once this alliance exists, any enemies have good cause to themselves find allies. And so on: an "arms race" of organization that expands the social web outward, weaving more and more villages together.

The speed with which hostility can thus move to higher levels of social organization, leaving harmony in its wake, has been much noted by anthropologists. The Nuer of Sudan, as studied by E. E. Evans-Pritchard early this century, were an especially vivid case. A Bor tribesman explained, "We fight against the Rengyan, but when either of us is fighting a third party we combine." Evans-Pritchard described the dynamic abstractly: "Each segment is itself segmented and there is opposition between its parts. The members of any segment unite for war against adjacent segments of the same order and unite with these adjacent segments against larger sections."

It sounds almost like a general law of history. And indeed, history offer lots of examples: formerly contentious Greek city-states forming the Delian League to battle Persia; five previously warring tribes forming the Iroquois League (under Hiawatha’s deft diplomacy) in the sixteenth century, after menacing white men arrived in America; American white men, two centuries later, merging thirteen colonies into a confederacy amid British hostility (and pithily capturing extreme non-zero-sum logic with the slogan "join or die").

In the short run, this impetus for aggregation may seem aimless. Alliances shift, tensions come and go, and large social structures dissolve almost a often a they form. But in the long run, over millennia, the worldwide trend has been toward consolidation, toward higher and higher levels of political organization. And one reason is war—intense, essentially zero-sum games that generate non-zero-sum games.

In past topics, listing technologies that elevate non-zero-sumness, I cited such contraptions as rabbit nets and huge salmon traps. The fact of war expands this list to include technologies that aren’t so obviously conducive to cooperation. The spread of iron weapons near the end of the second millennium B.C. may not ound like a recipe for social cohesion. But it was. The Israelites encountered iron weapons in the hands of the Philistines, who, according to 1 Samuel, brought "a very great slaughter, for there fell of Israel thirty thousand foot soldiers." In response, the loosely confederated tribes transformed themselves into a unified monarchy. The Israelites were warned that this would mean taxation and conscription, but they insisted: "We will have a king over us" so that "our king may govern us and fight our battles."


One could describe the congealing effect of war by saying it pushes people together into organic solidarity; it poses an external threat that impels them into closer cooperation. And one could describe the causes of solidarity emphasized in previous topics—the economic causes—as pulling people together; opportunities for gain originate within the society and draw people into closer cooperation. If you think about this distinction long  and hard, it is guaranteed to start seeming fuzzy. Still, the words "push" and "pull" provide a handy, if rough, terminology for describing two basic kinds of non-zero-sum forces in cultural evolution.

The relative importance of "push" and "pull" has been the subject of much disagreement. The dispute tends to focus on the several major thresholds of cultural evolution. Consider the "chiefdom" threshold. It is one thing for neighboring villages to become trading partners or even to attain a measure of "supravillage" political organization via loose confederation. It is another thing for neighboring villages to grant real, ongoing power to a central authority—for one village’s chief to become the "paramount chief." When this happens, a chiefdom has been formed.

The anthropological literature features many chiefdoms—from the indigenous peoples of Hawaii and Tahiti to the American Indian princess Pocahontas’s people, the Powhatan. And the anthropological literature features differing interpretations of them. Some scholars say the villages in chiefdoms were initially pulled together by trade and other economic sinews. Others say they were pushed together, by war or the threat of war. And some "push" enthusiasts go further and say war was doubly important. Not only were villages often united to better fight wars; they were united in the first place by war, by raw conquest. Carneiro has written, "Given the universal disinclination of human groups to relinquish their sovereignty, the surmounting of village autonomy could not have occurred peacefully or voluntarily. It could—and did—occur only by force of arms."

Carneiro—a fan of Herbert Spencer, and the editor of a volume of Spencer’s writings— was a student of Leslie White, who did so much to revive cultural evolutionism at mid-century. As it happens, White’s other star pupil, Elman Service, took a quite different, un-Spencerian view. Service (who died in 1996) envisioned chiefdoms often being formed when several nearby villages were bound by commerce; the village located at the nexus would naturally become the richest and would gradually grow dominant. It could all happen peacefully, Service believed. In his 1962 topic Primitive Social Organization, he wrote, "It is, in fact, clear from the record in some cases and probable in many others that small neighboring societies, or parts of them, often join an adjacent chiefdom quite voluntarily because of the benefits of participation in the total network." Carneiro’s reply, essentially, is: Networks, schmetworks. "Force, and not enlightened self-interest, is the mechanism by which political evolution has led, step by step, from autonomous villages to the state," he wrote in 1970.

Carneiro and Service have come to serve as icons of the "push" and "pull" views of the world. A group of social psychologists, studying social evolution in the laboratory, even set up elaborate simulations of the "Service condition" (different groups crafted products and traded with other groups) and the "Carneiro condition" (groups could trade, but one of the groups was allowed to confiscate the products of other groups). For what it’s worth, the experiment howed that leadership—an acknowledged paramount group—emerged in either event, and under the Service condition the standard of living was higher.

But in the real world, Service’s theory has been harder to validate. When the political merger of villages has been observed, it has usually come by aggression or intimidation.

And when consolidation has been voluntary, it has generally been to fend off external aggression. On the other hand, Service might point out, economically driven integration is a slower process than conquest or military alliance; hoping to have seen it during the brief history of anthropology is like taking a few seconds to watch grass grow. Besides, since Service’s death, some archaeologists have noted how little evidence of warfare they found amid the rubble that reflects the evolution of chiefdoms.


In a way, the difference between Carneiro’s "push" view of the world and Service’s "pull" view isn’t as stark as it sounds. Service did acknowledge, even stress, the frequency of war in prehistory. Indeed, in his view, conflict has been so persistent that to talk of the "causes of war"—as if it needed them—was almost to get the story backward. Better to think of war as a fairly natural condition and then examine the means by which people have avoided it; we should study not the "waging of war" so much as the "waging of peace."

Implicit in this view is the suggestion that the picture of war presented above—as a strictly zero-sum game—is too simple. And it is: war can be so mutually devastating that both sides clearly lose. In that case, it is a non-zero-sum game—specifically, you could call it a negative-sum game, in contrast to such positive-sum activities as economic exchange. (In The Art of War, Sun Tzu, recognizing war’s loselose aspect, counsels commanders to leave their enemies a means of escape.) Hence the incentive to "wage peace."

Of course, societies have a stubborn tendency to think of war a a zero-sum game. They heedlessly launch it even though their own men will surely die. What’s more, once the war is launched, it is full of zero-sum dynamics; when opposing soldier are in pitched battle, their fortunes are inversely correlated. For these and other reasons, I will continue to treat war a mainly zero-sum games, and add nuance as necessary. Nonetheless, Service has a point. Even if individual wars are often essentially zero-sum, featuring a clear winner and a clear loser, warfare—endless intermittent back-and-forth battling—can be, in the long haul, very bad for both sides. And such persistent negative-sumness is indeed grounds for waging peace.

In Service’s view, then, war is just another reason to value the harmony that comes from economic integration; it isn’t to fight wars that society evolves, so much as to escape wars, to carve out broader and sturdier war-free zones. Perhaps, Service suggested, "not only the evolution of government, but the very evolution of society and culture itself, depends on the evolution of the means of ‘waging’ peace in ever-widening social spheres—by continually adding new political ingredients to the social organization."

In theory, the first step toward waging peace would be to recognize that ongoing warfare is indeed a lose-lose game. It doesn’t take a game theorist to see this. In Papua New Guinea, one man observed: "War is bad and nobody likes it. Sweet potatoes disappear, pigs disappear, fields deteriorate, and many relatives and friends get killed. But one cannot help it."

The second step would be figuring out how to help it. And here some progress can be found in societies at all levels of organization. That includes the Northwest Coast Indians. When two peoples with a history of enmity could benefit through trade, a Big Man on one side might ritually bond with a Big Man on the other side. The two would exchange gifts and ceremonial names, becoming "brothers." Thereafter, wrote the anthropologist George Peter Murdock in 1934, "neither ever engages in war with the other, and the dwelling of either is a sanctuary where the other can alway find refuge." Through this channel the Haida gave dried halibut, mats, furs, and canoes to the Tsimshian in exchange for grease, candlefish, copper, and blankets.

Among "Big Man" societies generally, perhaps the most common means of "waging peace" is the lavish feast. (One more reason not to consider the Potlatch irrational.) An anthropologist who studied two societies in Papua New Guinea noted how inter-village feasts were used to create "regions of peace and stability in an inherently dangerous world."

Then again, to Carneiro and other "push" theorists, this sort of waging of peace looks suspiciously like a tool for waging war. Hosting a feast can win a village a military ally. And even if the feast merely neutralizes a potential foe, that may provide enough leeway for conquest on another front, or defense on another front. The more you think about "waging war" and "waging peace," the more inseparable they seem: a single coin, with Carneiro’s visage on one side and Service’s on the other.

Consider the Yanomamo of South America, intensively studied by the anthropologist Napoleon Chagnon. In the middle of Yanomamo territory, where villages are crowded together, war is especially common. Carneiro likes to stress that this core area shows signs of political evolution: larger villages and firmer political leadership, especially during war. On the other hand, Carneiro and Service might both cite—each with his own spin—the fact that this area also includes more inter-village bonding (designed, in Chagnon’s words, "to reduce the possibility of warfare between the principals"). And both might note—again, with different spins—Chagnon’s surmise that villages sometimes cultivate a kind of phony trade in the name of peace. A village, Chagnon believes, will refrain from making a particular tool precisely to create interdependence with a neighbor that does make it.

What Carneiro and Service—and for that matter Chagnon—would agree on is that in one sense or another, an atmosphere of war can foster the evolution of complexity. "Where warfare is intense and migration out of the area not feasible," wrote Chagnon, "there is selection for larger local groups and more elaborate intergroup relations."

As Service realized, the "waging of peace" long predates war per se. Feuds between two hunter-gatherer families don’t qualify as war. Yet, like war, they impede the gains of concerted economic behavior. To enjoy the fruits of suprafamilial organization, feuds must be suppressed. Peace must be locally waged.

And, as it happens, this local broadening of amity is further encouraged by the existence of slightly less local enmity—contention between clusters of hunter-gatherer families. And so it goes, up the scale of cultural evolution: the crevices of social organization—the zones of zero-sum contention between families or villages or chiefdoms or states—keep getting filled in by the cement of non-zero-sumness; and the zero-sumness thus displaced keeps retreating to higher levels of organization. And from there it continues to have its paradoxically congealing effect at lower levels.

Still, as Service stressed, the congealing also has its own internal logic; whatever caused the expansion of peace—war, the threat of war, the farsighted avoidance of the threat of war—peace is ultimately its own reward. Just ask the Auyana of New Guinea. After they were pacified by Europeans, the men rejoiced in their newfound ability to go urinate in the morning without fear of ambush. The first step toward a productive day. Also the first step toward trading with the former ambushers, thus weaving a web of interdependence which can fortify the peace that’s been waged.

Note how war—or at least the threat of it—narrows the range of choice. In the previous topic I more or less assumed that people tend to harvest the fruits of non-zero-sumness; they just naturally like to raise their standard of living and to insulate themselves against risk. This fondness for bounty and security assures that they will try to realize positive sums, experimenting with new technologies and new forms of social organization; and this realization sustains the basic directional drift of history.

Whether I’m right in this claim about human nature certainly matters, but in a context of war—the context of human history—it matter less. For in that context people have little choice but to pursue economic and organizational advance. After all, unproductive societies tend to get squashed. An anthropologist described one group of Northwest Coast

Indians, trapped between powerful neighbors, as being "ground to bits"—reduced to scurrying around nibbling on raw food lest campfires attract attention.

People who are conquered may live on after conquest, and they may be lucky enough not to be enslaved; but they will almost surely wind up adopting a new system, the system of the conquerer. And conquerers’ systems tend to be productive, to involve, for example, a relatively advanced division of labor. One way or another, non-zero-sumness wins in the end.

All of this brings us back to Kant’s emphasis on "unsocial ociability." The realm of "sociability"—the geographic scope within which peace reigns—has grown massively since our hunter-gatherer days. And commensurately massive quantities of unsociability have been overcome. Yet they are often overcome under the ironic stimulus of higher-order unsociability. To put this dynamic of cultural evolution in the Darwinian language of natural selection: what is "selected for" is larger and larger expanses of non-zero-sumness, but one of the main selectors is the zero-sum dimension of war. In this sense, waging war, in the end, is waging peace.

An authority on human behavior once remarked that if two people stare at each other for more than a few seconds, it means they are about to either make love or fight. Something similar might be said about human societies. If two nearby societies are in contact for any length of time, they will either trade or fight. The first is non-zero-sum social integration, and the second ultimately brings it.

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