Hunter-Gatherers and Collective Action

Large-scale cooperation in small-scale societies

Today we'll take a look at an important paper that came out last year by the noted anthropologists Rob Boyd and Pete Richerson (all citations will be from the paper unless noted otherwise). While not as well known to the general public as Graeber and Wengrow, the pair have long studied cultural evolution in complex societies.

Complex societies are a something of an evolutionary puzzle. By what means do humans cooperate in such large groups? Our closest relatives—chimpanzees and bonobos—do not do that; certainly not to the same extent. In fact, no mammals form the kinds of large, scalable, flexible societies that we do.

What makes this even more mysterious is how these capabilities evolved. If we have spent the majority of our evolutionary history in small bands of closely related individuals, then how is it possible that we are able to form the kinds of large-scale cooperative societies that we see all around us today? If our social evolution was primarily in the context of small-group interactions this would seem to be impossible. This calls out for an explanation.

Sometimes this is explained by kin-selection. We're hard-wired to provide assistance to those who share much of the same genetic material as we do, the thinking goes. Yet in the kinds of large-scale societies we live in today we somehow cooperate with hundreds of unrelated individuals each and every day. Key to this sort of cooperation is the expectation that others will cooperate.

Jean-Jacques Rousseau, in his Discouse on Inequality, framed this through the lens of a 'stag hunt.' In his analogy, if a group of hunters decides to cooperate they can catch a stag which will yield each hunter the most meat. But the catch is that everyone needs to buy in. If they can't get the buy-in, they will instead hunt rabbits individually. This requires no cooperation, but will yield each individual hunter less meat. This means that the total meat bagged by the hunters will be less than if they had agreed to cooperate and went after the stag instead. Economists call these “collective action problems.”

David Hume framed this in terms of a rowboat. Each individual in the boat can choose to do whatever they like with the oar in their hand. Yet the boat will only successfully move forward if they all decide to do the same thing with their oar. Key to both of these things are "other-regarding" behaviors, as well as belief, as Yannis Varoufakis describes¹:

Note the most important points here:

• The hunters prefer to hunt the stag together rather than to hunt hares individually.

• Each will dedicate himself to the stag hunt if he is certain that the others will do the same.

• In the end, if they believe that they will hunt the stag in perfect unison, they will hunt the stag in perfect unison. Equally, of they do not believe it, they won't.

This is a lovely example of the power of optimism, but also the demonic strength of pessimism. In the context of the stag hunt, both are self-fulfilling. And this is the essence of Rousseau's allegory: if a goal can be achieved only collectively, success depends not just on all individuals pulling together but primarily on each individual believing that every other individual will do so.

This shows the paradox of large-scale cooperation which has fascinated and perplexed scholars from Rousseau to today's mathematical game theorists. The question is, how did these kinds of behaviors arise if we spent our evolutionary history living exclusively in small-scale foraging groups? As Boyd and Richerson explain, "Many scholars believe that large-scale cooperation is rare among simple foragers, and so would not have had much effect on the evolution of our cooperative psychology."

So we have an evolutionary puzzle. Unlike most other vertebrates, people in contemporary human societies engage in costly collective action in large, unrelated groups. The psychology that gives rise to this cooperation must have been shaped by natural selection in Pleistocene foraging societies, but the mechanisms used to explain cooperation in other species do not explain the scale of contemporary collective action among humans.

To help explain this mystery, Boyd and Richerson provide numerous line of evidence that large-scale cooperation was indeed practiced by hunter-gatherer societies all over the world; and furthermore, has been practiced long before agricultural societies existed. These behaviors appear to go back all the way into the Pleistocene and perhaps even back to our pre-human ancestors.

Because of that, it has a direct bearing on the arguments presented in The Dawn of Everything that human nature did not undergo some kind of phase change when we settled down and started farming. Instead, things like farming and urbanism can be seen as extensions of the same behavior which evolved in the context of hunting and gathering.

Let's take a look at their evidence.

Communal hunting

The first line of evidence they provide is communal hunting. Unlike stalking animals through the bush, communal hunting required advanced planning and the participation of large numbers of people in order to succeed.

In communal hunting large herds of animals are forced into a place where they can be ambushed by a group of hunters. Typically herds are either driven over some sort of carapace where they fall and become injured or incapacitated, or else toward a river or other body of water where they are picked off as they attempt to ford it. They can also be driven into a confined space like an arroyo or canyon from which escape is difficult or impossible. Some techniques involved driving animals into very large game nets where they could be captured. This technique required a high degree of cooperation to succeed, and a significant investment in labor to construct the nets.

To make these practices successful, groups often build structures known as drivelines, or game fences, out of stone or other materials. These drivelines could potentially extend for miles. As the stampeding animals collide with the drivelines they are channeled en masse to a predetermined location for ambush. Hunters also built corrals to funnel the animals into in order to pick them off, and blinds to make them invisible to their prey.

Communal hunting was once very common throughout North America. The Inuit and Athabascan cultures—both considered small-scale foragers—practiced communal hunting for caribou (also known as reindeer) in the high Arctic. The Inuit constructed drivelines for carbou hunting (known as inukshuk) out of rock cairns supplemented with willow branches, turf and hides. These structures varied in length from a few hundred meters up to 30 miles (50 kilometers).

The caribou migrated north in the spring and south in the fall. In the spring, the animals were lean and their skins were punctured by nesting fly larvae making their hides less useful. In the fall the animals were fatter and the holes had healed, and this was the time when communal hunts were organized. Evidence indicates that large numbers of people were involved in these activities.

By the twentieth century, this practice had been mostly abandoned because the provision of guns and rifles made solitary hunters able to kill large numbers of animals. However, anthropologists have determined that before this time only communal caribou hunts could meet the needs for survival, not only for food but also for hides used for clothing and bedding. The average Inuit household required 30 hides every year to meet their needs, meaning that communal game drives must have been a common occurrence in these harsh and unforgiving regions as long as people had lived there.

Archaeological evidence indicates that communal hunting for caribou has been going on for a long time. Drivelines on Victoria Island by the Dorset Culture date back 800 years. Structures resembling drivelines have been found under Lake Superior in what would have been an isthmus 7500 to 10,000 years ago. In the Canadian barrenlands, some sites were in continuous use for 6000 years as indicated by more than six feet of strata with tools and caribou bones.

Another well-known example is the Great Plains bison (also known as buffalo) hunts. Before the arrival of horses and firearms brought by Europeans, driving herds of animals over a cliff was the primary way the natives of the Great Plains obtained large numbers of buffalo.

Bison are agile for their size and can turn even at a full gallop. In order to drive huge herds of bison, then, large numbers of people must have participated. Based on the amount of bones found at archaeological sites, at minimum hundreds of people must have been involved in these communal game drives. At one site in eastern Colorado dating to 8500 years ago, at least 200 animals were killed at one time yielding around 57,000 pounds of meat.

Such a large quantity of meat also required intensive processing so that it wouldn't spoil. Hundreds of animals had to be dragged from the cliff face, skinned, and butchered in a short amount of time. These cultures used every part of the animal—nothing was wasted. Hides were used for tipis, intestines for bowstrings, and bone grease was extracted for pemmican. To accomplish this, people probably organized themselves into a kind of "assembly line" in order to process the carcasses quickly. This also suggests a high degree of coordination among the hunter-gatherers of the Plains.

People have acquired bison using communal methods for as long as they have been in North America. Hundreds of sites have been identified. The earliest date to the Clovis period, shortly after the arrival of people in the Great Plains. Larger sites with the remains of more than 100 animals become common in the Folsom and Paleoindian periods about [12,000 years ago], and very large communal hunts utilizing cliff jumps become common about 6000 years ago.

For example, people used the Head-Smashed-In jump from 5700 to about 700 BP...the invention of pemmican for storage and the arrival of the bow 2000 years ago made large-scale hunts more profitable. Communal hunting declined in the Southern Plains as people became semi-sedentary villages who mixed farming and foraging.

Bison weren't the only animals hunted communally by Native Americans. Pronghorn antelopes were hunted in the Southwest and the Great Basin by the Shoshone and Paiute—both mobile foragers. This was a major feature of their economy. These animals are extremely fast and notoriously skittish, making the use of game fences and corrals the most effective way to hunt them:

Typical drives utilized large corrals and drift fences or drivelines. The Whiskey Flat pronghorn trap northeast of Mono Lake provides a well-studied example. A fence 2.3 kilometers long (1.4 miles) channeled the pronghorn into a large circular corral where they were shot by hunters armed with bows. The fence and corral were built from about five thousand juniper posts spaced abut 50 cm apart and braced with stones. At other sites, corrals and fences were built using stone. For example, the Forest Sage drift fences are built with dry stone masonry. When the fences were new they were about 1 meter high, 1 meter thick, and about 1.1 kilometer long.

Evidence indicates that this hunting technique extends back at least 10,000 years in this region based on sites like Trapper's Point in Wyoming. Ethnographic evidence indicates that hunting party sizes ranged from 18 to 100 people, and several hundred people are estimated to have been required to construct the game fences.

Alpine drivelines were constructed in the Rocky Mountains to intercept herds of elk and big horn sheep at 3000 meters above sea level. Some drivelines could be quite long—a five-mile (8-kilometer) stone wall blocked Rollins Pass and was used by multiple bands. The oldest of these sites date to 8000 years ago and become more common after 3000 years ago. Mountain sheep were hunted communally in Wyoming and Montana in the eighteenth century, although because game fences were built out of perishable materials it is uncertain how far back this practice went.

Hunting using large nets has been observed in the Congo Basin of Africa. Communal hunts of animals like kangaroos and wallabies were important to the natives of Australia involving large numbers of people from a wide area and from many different tribes:

Communal hunts in Australia were often associated with large seasonal gatherings that brought together people from many residential groups. Historical accounts speak of "whole tribes" gathering. Sometimes people gathered to hunt, but other times people gathered for ceremonial reasons or to harvest seasonally available plant resources. For example, groups of 3000 people gathered to harvest bunya fruits in Queensland. Communal hunts were important for large gathering because they were capable of producing sizable surpluses.

These techniques were used in Southwest Asia for millennia. All across the Levant, enclosures known as kites (because of what they look like from the air) have been discovered which were used for gazelle hunts. Over a thousand have been discovered in Jordan alone. These consisted of a pair of stone walls arranged in a V-shape that converged on a narrow canyon and were very similar to those used for pronghorn hunts in North America. These were used for thousands of years—some groups in Arabia (such as the Solluba) continued to use similar structures for hunting into fairly recent times.

Moreover, evidence for communal hunting dates extremely far back based on large accumulations of bones and butchery marks found at archeological sites. The kinds of large ungulates and proboscidea which gathered in herds would have been even more abundant in the Pleistocene than in more recent times. Evidence for communal hunting in Europe dates back to 124,000 years ago. The oldest site at the Gran Dolina caves in Spain dates back to 400,000 years ago and was probably carried out by Homo heidelbergensis. Additional evidence has been found from the Middle Stone Age in Africa. There is even pictographic evidence of people using drivelines and communal hunting techniques in Ice Age Europe:

Thomas Kehoe, an authority on Great Plains bison hunts, has argued that these images [at Lascaux and Altamira caves] contain images that picture drivelines and communal hunts.

At Lascaux, one of the famous "Chinese" horses stands below a fence-like structure, and on either side of the horse are feathery leaves like those used to augment drivelines in North America. Other images contain lines of dots that may represent lines of cairns used in drivelines. For example, on the Axial Wall as Lascaux, a horse and reindeer run parallel to lines of dots, and one of the ends in a square box perhaps indicating a corral. Many other images contain features that could represent drivelines.

In summary, communal foraging required the cooperation of large numbers of people in order to succeed. In addition, large numbers of people were required to construct “public goods” like nets and drivelines and process the resulting kill, requiring significant investments in time, labor, and materials. We know that these activities were undertaken by hunter-gatherer groups on every continent. Furthermore, evidence shows that these techniques have been practiced by humans for at least tens of thousands of years, possibly even going back hundreds of thousands of years to our earlier ancestors.

Fishing traps and weirs

Weirs consist of low walls constructed underneath a body of water like a river or inlet, usually out of stone. Fish swim over the wall at high tide and are trapped at low tide in the confined area where they can be easily caught. They can also be kept in these confined areas until ready to harvest, making them a form of food storage. Often these structures are dismantled at the beginning of the spawning season so that fish can find mates. Fish traps are maze-like semi-circular or angular structures usually built out of wooden posts or reeds with an upstream opening that fish swim into with the current but have difficulty finding their way out of.

These sorts of traps and weirs have been constructed by hunter-gatherers all over the world. Two of the most notable cultures that made extensive use of them were the foragers of the Pacific Northwest coast of North America and the coastal dwellers of Australia. They were also used by the Jōmon people of Japan, among many others.

A similar technique is the construction of artificial wetlands to "farm" certain varieties of aquatic species such as eels. In a previous post, I described the site of Budj Bim (Mount Eccles) in Australia which was first constructed at least 6,000 years before the present (before the construction of Stonehenge). The inhabitants of Australia built similar artificial wetlands in a number of locations:

Weirs [were] used to harvest silver eels throughout southeastern Australia. During the eel migration, 800-1000 people gathered at the most productive sites. The oldest of these traps date to 6600 BP. Aboriginal people constructed two large facilities to aid in harvesting eels.

Near Mount William, a weir redirected the river into a large maze of trenches that covered about 6 hectares and involved thousands of meters of trenches. At Toolondo, Aboriginal people built a 2.5 kilometer long canal, 2.5 meters wide and 1 meter deep, which linked two natural swamps. The canal increased eel habitat because it linked one of the swamps to the ocean where the eels breed.

Fish traps, weirs and artificial wetlands all took significant investments of time, materials and labor to construct and maintain. For example, on Murray Island in the Torres Strait, traps were built out of lava rock hauled from the bush. Each meter of wall required over 1100 pounds of stone and the walls averaged nearly 1000 feet (300 meters) long. Anthropologists estimate that the average weir took 4300 trips to build. It was probably built quickly too, since an incomplete fish trap is not very useful. Often traps and weirs were dismantled and rebuilt every season. Every spring the Yurok built a weir out of timber across the Klamath river.

Clearly, these types of things took more than the labor of small, isolated bands could accomplish. And yet they were built by hunter-gatherers all over the world, and have been for thousands of years.

Environmental improvements

Although foragers are often depicted as making no permanent investments in their lands (unlike farmers), the truth is that they used a variety of methods to enhance the productivity of their territory. Often these methods worked with—rather than against—the surrounding environment and were so subtle that later cultures mistook these landscapes as "natural" when in fact they were the product of thousands of years of deliberate human intervention, as Graeber and Wengrow describe in The Dawn of Everything:

There are many ways, other than European-style farming, in which to care for and improve the productivity of the land. What to a settler's eye seemed savage, untouched wilderness usually turns out to be landscapes actively managed by indigenous populations for thousands of years through controlled burning, weeding coppicing, fertilizing and pruning, terracing estuarine plots to extend the habitat of particular wild flora, building clam gardens in intertidal zones to enhance the reproduction of shellfish, creating weirs to catch salmon, bass, and sturgeon, and so on.

Such procedures were often labour-intensive, and regulated by indigenous laws governing who could access groves, swamps, root beds, grasslands, and fishing grounds, and who was entitled to exploit what species at any given time of year. In parts of Australia, these indigenous techniques of land management were such that, according to one recent study, we should stop speaking of ‘foraging’ altogether and refer instead to a different sort of farming. (pp. 149-150)

Two techniques were especially common. One was burning the landscape to drive animals, control the biome, and promote the growth of favored species. Another was the construction of water channels and dams to divert water to desirable areas. We have evidence of deliberate burning of the landscape by humans as far back as 92,000 years ago. "Firestick farming" was a common practice of aboriginal Australians for thousands of years.

People in many foraging societies undertake activities aimed at increasing the productivity of the local habitat. For example, Native American groups along the Mississippi and the Colorado Rivers sowed the seeds of wild grasses on mudflats exposed after seasonal floods. Other groups transplanted tubers and fruit trees. The ache of Paraguay cut down trees and returned months later to harvest beetle larvae from the dead tree trunks. The Owens Valley Paiute in California built diversion dams and canals to irrigate land and increase the growth of water-loving plants with edible roots. The largest of these irrigation areas covered about ten square kilometers and was fed by canals that were several kilometers long.

In fact, one researcher has argued that the entire continent of Australia was effectively "terraformed" by human populations over the last 50,000 years turning it into what he refers to as "The Biggest Estate on Earth." Australian aboriginal societies are often depicted as the quintessential small-group tribal foragers (along with those of southern Africa), yet they were able to successfully transform an entire continent into a park-like setting where they lived sustainably for thousands of years until the arrival of Europeans. Similar "park-like" settings were described by the first European visitors to North America. Today, by contrast, just 240 years after the European arrival, Australia has lost more species to extinction than any other continent and nineteen of its ecosystems are on the brink of collapse: Australia's environment in 'shocking' decline, report finds (BBC)

War and peace

Warfare is perhaps the most important and most common form of large-scale human cooperation, even though the ends it is used for are monstrous. Evidence for warfare among hunter-gatherers is highly contentious. Clearly there were not enough people in hunter-gatherer societies to engage in the kind of large-scale, coordinated, multi-year campaigns as agricultural peoples. There is also the confounding effect of surrounding societies on hunter-gatherers, which works both ways (these larger societies could suppress tribal warfare as well as foment it). Nevertheless, Boyd and Richerson present ethnographic evidence that, on at least some occasions, hunter-gatherers could engage in fairly large-scale conflicts.

Much of this evidence comes from Australia where basically everyone lived in small-scale tribal communities. Reports of tribal warfare by observers and anthropologists over the years describe incidents where hundreds of people engaged in pitched battles. A conflict over access to wells in the Western desert left 20 people dead on each side indicating a substantial number of combatants. An attack at the Finke River in 1875 killed 80-100 men, women and children. The Yolngu (Murngin) people of Australia recognized three types of conflict: a maringo: or night raid; a milwerangel: an open, formal conflict between two groups; and gaingar: a large-scale regional conflict involving multiple tribes. Rock art in Arnhemland appears to depict large-scale conflict going back 6,000 years.

In North America, the Iñupiaq of Western Alaska lived in fishing and hunting camps during the spring and summer and gathered in villages during the fall and winter. Villages of various sizes were organized into territorial groups anthropologists referred to as "nations." There were 10 nations in the region around Kotzebue Sound with an average of 470 people and a territory of 8600 square kilometers. Raids and battles between nations were frequent, with 77 recorded in the first half of the nineteenth century. Raiding parties armed with bows, lances and knives conducted surprise attacks, traveling up to 800 miles at a time to engage in nighttime raids.

One raid involved 350-400 people ambushing a village of 600. Women could be raped or taken as slaves. Some Iñupiaq villages were surrounded with defensive stockades and booby trapped stakes made of sharpened caribou bones driven into the ground. Occasionally conflicts between nations boiled over into pitched battles involving exchanges of archery fire that could last for hours. There is also ethnographic and archaeological evidence of large-scale fortifications in eastern Oregon and Washington predating the arrival of Europeans and horses.

Peace is as much a product of large-scale cooperation as war. War and conflict is costly to all involved, and so it is to everyone's interest to keep it under control. This was the case thousands of years ago as surely as it is today. As Boyd and Richerson write: "A common assumption is our Pleistocene ancestors lived in small bands that were hostile to one another. We think the historical, archaeological, and ethnographic evidence suggests that diplomacy on the part of such societies can hold together large alliances and make peace over large areas."

Evidence indicates that diverse groups were able to compromise and negotiate peace among themselves. For example, tribes in California arranged informal codes that helped mediate individual conflicts to keep them from escalating. These rules extended across multiple tribes and villages. Key to this system were: 1.) All rights, claims and possessions were individual, not collective; 2.) Any unsanctioned punishment by an individual was also an offense; and 3.) Any offense could be valued in material terms, whether material in nature or not (such as defamation or slander)². Although there was no formal authority, informal "judges" known for their wisdom could act as mediators.

Thus, although Northern California tribes were wary of strangers from other groups, active hostilities were infrequent and casualties usually few. In times of peace, those with goods to trade could approach a village of another tribe and announce themselves and request to speak to their trade partners. Molesting, robbing or killing such individuals would constitute a grievance that eventually would have to be compensated, perhaps after a costly war. So traders could feel reasonably safe in conducting their business.

Trading zones extended over large swaths of North America which would be impossible in an atmosphere of incessant tribal warfare, meaning that methods for establishing and maintaining peace must have also been widespread. These trading areas date back many thousands of years. Trade networks also existed across Australia and included exchanges with New Guinea and Indonesia. Evidence of similar networks has been found in Paleolithic Europe and Africa. Clearly, none of this would be possible if we were "hard-wired" to attack anyone outside our small, isolated tribal community or kin group. Instead, we are much more likely to cooperate with strangers than kill them.

Based on the evidence they present, Boyd and Richerson conclude:

This evidence is not consistent with the hypothesis that cooperation among Pleistocene hominins was limited to small band-size groups, but instead often extended to larger scale groups, even to the cross-cultural scale in the case of military alliances and trade partnerships. This suggests that the psychological mechanisms that support large-scale cooperation in contemporary societies evolved to support large-scale cooperation in Pleistocene societies of mobile-hunter gatherers, and explanations of contemporary cooperation based on mechanisms evolved to support only small-scale cooperation are not correct.

All of which contradicts the widespread notion of hunter-gatherers being "primitive" simple people who only lived in tiny bands of 20-30 people before the dawn of agriculture. This is a major point made by Graeber and Wengrow in The Dawn of Everything.

Some have used this to argue in favor of the "diverse origins" thesis, such as the one presented by Singh and Glowacki we looked at a few posts back. They take this as evidence that large-scale civilizations with significant wealth differences and high levels of inequality must have existed all the way back in the Pleistocene. However, the majority of evidence for large-scale cooperation presented by Boyd and Richerson comes from small-scale band societies. There is still scant evidence for hierarchical societies in the Pleistocene, and I don't think we need to posit complex, hierarchical civilizations in prehistory to explain large-scale human cooperation. There is no inherent contradiction between living in small groups and cooperating on large scales or making investments in “public goods.” Neither is despotism an absolute requirement in order to coordinate large groups of people.

To me, this a hopeful observation. What it suggests is that large-scale human cooperation is possible even in the absence of top-down command and control structures. It also preserves the "egalitarian origins" theory, which I still think is the most plausible theory for human origins based on the evidence. If indeed we evolved to cooperate with large numbers of strangers even while living primarily in band societies, it also helps make the subsequent course of human history during the Holocene a lot easier to explain.

Of course, drivelines and fishing weirs aren't the space shuttle. But the possibility of cooperation without a seperate class of greedy despots and oligarchs lording over the rest of us and hoarding all the wealth gets us back to the core message of anarchism, which is what David Graeber spent his (too short) life advocating for.

Next time we'll take a look at some of the additional evidence he presents in the book that non-farming societies were far more complex and sophisticated than we previously believed.

1. Talking to My Daughter About the Economy, p. 95. Emphasis in original.

2. Ran Prieur comments: "March 1. I just read this in the book The Dawn of Everything. Among the Yurok, a tribe in northern California, there was a 'requirement for victors in battle to pay compensation for each life taken, at the same rate one would pay if one were guilty of murder.' There's no reason we can't have that rule in the modern world, except the continuing political influence of states that want war murders to be free."