Being human: we were born to cooperate

The human ability to cooperate is what elevates us above apes and monkeys.


The vast majority of humans today have grown accustomed to living in societies with high levels of inequality. Indeed, it is tempting to focus on the past several thousand years of human history in modeling sociopolitical organisation because the changes that occurred in this period so radically and rapidly transformed the character of human society. However, the basic genetic predispositions of humanity’s underlying sociopolitical structure were forged over a much longer period of time. Modern authoritarian hierarchies represent a late development, a fraction of a percentage of our species’ existence. Conversely, for tens of thousands of years, egalitarian hunter-gatherer societies were widespread. And wherever they’re still found—in Africa, South America, Asia or elsewhere—these societies have many characteristics in common.

As a large body of anthropological research shows, long before we organized ourselves into hierarchies of wealth, social status and power, these small, self-governing groups developed a level of cooperation which is still our species’ defining characteristic today. Humans regularly do something that no other complex social mammal does: we cooperate with strangers, people we’ve never seen before and will never see again. None of our great ape relatives comes close. So what made us, one of the African great apes, so different from the others?

A cooperative animal

Non-human primates generally form hierarchal social communities with either dominant individuals (alphas) or small coalitions at the top and lower-ranking individuals below. In contrast, extant small-scale human forager bands of hunter-gatherers, who arguably resemble the earliest human communities in the late Pleistocene era, typically share political power equitably with a variety of cultural status leveling mechanisms discouraging individuals from adopting alpha-like behaviour. Suppressing our primate ancestors’ dominance hierarchies by enforcing these egalitarian norms was a central adaptation of human evolution. It enhanced cooperation and lowered risk as small, isolated bands of humans spread into new habitats and regions across the world, and was likely crucial to our survival and success.

In general, humans seem predisposed to cooperate. In experimental games in which there is no chance that the highest paying strategy of deception will be discovered, human subjects are still more likely to cooperate. Other studies show how most people, both children and adults, will choose to punish wrongdoers even at personal cost. Indeed, the need to cooperate, and protect ourselves from individuals who could exploit our cooperation, appears to be part of our evolved psychology.

It may also account for our longevity as a species: researchers modeling demographic simulations have found that, rather than imparting advantages to the group, unequal access to resources is inherently destabilising. Counterintuitively, the fact that inequality was so destabilising caused those societies to spread by creating an incentive to migrate in search of further resources, leading to conquests of the more stable egalitarian societies. In other words, inequality did not spread because it is an inherently better system for survival, but because it creates demographic instability, which drives migration and conflict and leads to the cultural or physical extinction of egalitarian societies.

Of course, in modern democratic societies, there is still enough willingness to bend to authority to ensure that return to a tyrannical social dominance hierarchy remains a constant threat and often a reality. But one anthropologist after another has been amazed by the degree of equality, individual autonomy, indulgent treatment of children, cooperation, and sharing in hunter-gatherer cultures they have witnessed. In this essay I will describe some of the most compelling cultural and physiological strategies which evolved to enable hunter-gatherers to maintain their egalitarian ways over millennia thus allowing our species to overcome the barriers to trust which limit our closest primate relatives.

Investing in the present

James Woodburn’s analysis of the shared cultural traits across the world’s hunter-gatherer societies classifies them as either immediate return or delayed return. In the former, group members obtain direct return from their labour in hunting and gathering, with food lasting at most a few days. The tools and weapons they use are highly portable. Delayed-return systems by contrast are characterised by greater investment in more complicated and costly tools (boats, nets, beehives, and the like); a delay in yield from labour; private ownership and accumulation of food, capital and land. These societies exhibit forms of social stratification akin to those in modern societies: social dominance hierarchies in the form of lineages and clans and dependency relationships including rights of men over women. But the fossil record suggests that delayed-return human societies are a more recent innovation; homo sapiens evolved predominantly in the context of immediate return systems, so that’s where we’ll be focusing here.

Woodburn draws a clear link between an immediate-return economy and an assertively egalitarian society. Hunter-gatherers are not passively egalitarian, but are actively so. They are ‘fiercely egalitarian’, having to work at resisting their own and others’ tendencies to dominate through rigorously enforced norms that prevent any individual or group from acquiring more status, authority or resources than others. Woodburn termed these social practices ‘leveling mechanisms’, social, political, and material factors that intentionally discourage hierarchy.

The Hadza pound baobab seeds into nutritious flour. Photos by Katrin Redfern/Andrew Stern

Modern-day egalitarian, immediate return societies include the Hadza in Tanzania and the San in Botswana and Namibia, among whom Woodburn conducted his research, as well as some pygmy groups in Central Africa, several groups in India, such as the Andaman Islanders, the Hill Pandaram, and the Nayaka, and in Southeast Asia, the Aeta, Batek, Maniq, Penan, and others. This worldwide distribution of immediate return traits among indigenous hunter-gatherers suggests that such social systems are likely to have great antiquity, their remarkable similarities forming the ‘the human social-cognitive niche’; the mental attributes, or deep social mind, distinctive to modern humans, comprising of hyper-cooperation, egalitarianism, cultural transmission, language, and mind reading, also known as intersubjectivity.

Such societies are politically egalitarian since no one can coerce others to do their will. Women and men participate equally in decision making and anyone who makes a bid for higher status, using their influence to acquire wealth or prestige or attempts to coerce others, is subject to teasing and ridicule, especially from the elders, gossip, and if necessary is ostracised, and may even be exiled. If that doesn’t work, ready access to lethal weapons also acts as a leveling mechanism.

Economic relations remain egalitarian through leveling mechanisms that impose sharing, called demand sharing, on anyone with more than they can immediately consume, which prevents saving and accumulation, which can be used to assert power over others. Those that achieve big yields—the killing of large game, say—should be both self-deprecating about their success and must also share their assets with all others in their social group (including free-riding individuals who rarely hunt). Meat butchering and distribution are done as a rule by individuals other than the hunter, whose family does not get a bigger share than other families.

If a man boasts about his hunting prowess, he is ridiculed; and mocking stingy individuals is an effective leveling mechanism. It would be a serious offense—likely enforced with threats of violence—for the hunter to eat a kill by himself. Woodburn’s interpretation is that it is something imposed on the hunter by the community, similar to ‘taxation on incomes of the successful in our own society. The successful pay more than the less successful and are obliged to do so. They are not able to establish greater claims in the future through having paid more in tax and do not derive much prestige from having contributed more to the tax pool than they have withdrawn in benefits.’

Life on the move

Another diagnostic of truly egalitarian hunter-gatherers is whether people can live where they choose. Social groupings are flexible and constantly changing. The ability of individuals to attach and detach themselves at will from groupings and from relationships makes them ‘potentially autonomous’. Relationships between people emphasize sharing and mutuality but do not involve long-term binding commitments and patterns of dependency. In contemporary hunter-gatherer tribes, men and women tend to have equal influence on where their group lives and who they live with. But studies show African hunter-gatherer women lose status and freedom as they become more sedentary. This happens when women are less able to move and avail themselves of support networks. African hunter-gatherers especially resist the atomization of living in nuclear families, using many mechanisms to create links between far-flung friends and relatives.

Individuals in immediate return societies have few personal possessions and appear unwilling to accumulate more. This is the result of a powerful cultural norm about the inappropriateness of an individual owning a large amount of possessions. Central to this and other leveling mechanisms is that it disengages people from property, and from the potentiality of property to create dependency. Lastly, each member of such a society has direct individual access to the resources on which they depend for their survival, making it impossible for certain individuals to restrict access to resources as the basis of their power. People are dependent on the group as a whole but not on specific other people for access to basic requirements.

The role of Machiavellian intelligence

Another way to look at leveling mechanisms is that hunter-gatherers have not abolished dominance but have, instead, turned it on its head. In a theory proposed by Christopher Boehm called ‘reverse dominance’ the hunter-gatherer band as a coalition acts as a dominating force, to suppress the behavior of any individual to monopolize reproductive and other resources.

Egalitarianism is difficult to explain using Darwinian theory premised on competition. We can understand it in evolutionary terms by employing the theory of ‘Machiavellian intelligence’, a subtle idea that sees animals in complex social groups competing in evolutionary terms by becoming more adept at cooperation, evolving ever greater capabilities for negotiating alliances. In this theoretical perspective, then, the significant increases of brain size in the primate order, from monkeys to apes, and then from apes to hominins, result as survival strategies shift towards increasing social complexity and the ability to create alliances.

At a certain point, the ability to operate within alliances exceeds the ability of any single individual, no matter how strong, to dominate others. If the dominant subject tries, he (and with primates it’s usually a ‘he’) will meet an alliance in resistance who together can effectively counter him. Once that point is reached, the logical strategy becomes not to try to dominate others, but to use alliances to resist being dominated oneself. Erdal and Whiten used this theory of ‘counter-dominance’ to explain the evolutionary emergence of egalitarian attributes such as the leveling mechanisms described by Woodburn. Extending the argument further, anthropologists Chris Knight and Camilla Power suggest that human symbolic culture itself emerged from female coalitionary counter-dominance strategies.

A world of play

A further way that hunter-gatherers maintain their egalitarian ethos is by deliberately cultivating that aspect of human (and mammalian) nature that most effectively suppresses the drive to dominate and encourages cooperation—playfulness. According to psychologist Peter Gray, hunter-gatherers suppress the tendency to dominate and promote egalitarian sharing and cooperation by deliberately fostering a playful attitude in essentially all of their social activities.

Children growing up in hunter-gatherer cultures have more opportunity to play than do children growing up in any other culture that anthropologists have observed, and as they become adults their playful ways continue. Hunter-gatherers’ approach to work is playful in that it is social (people hunt and gather with friends and kin, in groups) and always voluntary—nobody is required to perform these tasks, they will be fed anyway. Their religions are playful, highly imaginative and non-dogmatic, highlighting vulnerable gods. Anthropologist Jerome Lewis points out that tribes such as the Mbenjele of central Africa have the same word for play as for ritual.

Adults, as well as children, engage regularly and playfully in music, dance, art, and noncompetitive games. By infusing essentially all of their activities with play, hunter-gatherers keep themselves in the mind frame that most strongly, by evolutionary design, counters the drive to dominate others. Even their means of putting down someone’s budding attempts to dominate are playful, at least at first. They may make up a silly song about the person, to gently deride excessive pride or imitate them in a humorous way. If the early humor doesn’t work, however, the teasing will become more pointed and less playful.

Crucially, in humans playfulness embraces sex, with each gender taking turns to playfully dominate the other. Among other primates, it’s sexual conflict which puts an end to play: as they reach sexual maturity, the play fights turn deadly and it’s sex which most decisively dispels the carefree atmosphere of the earlier years. Former playmates become rivals and conflict is endemic because for monkeys and apes a fight over sex is one they can’t afford to loseFor humans ritualized play pervades the very arena which in other primates leads concurrently to violence. Sex no longer shuts down play. Once sexual violence has been marginalized, trust can stabilize and among trusting adults, imaginative play is then free to extend throughout the life cycle.

The kids are alright

Hunter-gatherers maintain their ethos of equality through permissive childrearing practices which engender feelings of trust and acceptance in each new generation. As related by anthropologists such as Elizabeth Marshall Thomas, among the first to study the Ju/’hoansi of Africa’s Kalahari Desert, they trust infants’ and children’s instincts, and so they allow infants to decide, for example, when to nurse or not nurse and encourage children to educate themselves through their own self-directed play and exploration.

They do not physically punish children and rarely criticise them. Children are also encouraged to be independent; by the age of eight Hadza children in Tanzania are already hunting and gathering more than half of the food they need each day. In this way neither the parent-child relationship, nor the relationship of older to younger more generally, are a training ground for relationships of authority; instead they provide a model for personal decision-making and the possibilities of self-reliance, in cooperation but not dependency.

Open your eyes

The legacy of our egalitarian past is evident in our physiology, perhaps the hallmark of which is seen in the design of our eyes. Humans are the sole primates among more than 200 species to have evolved eyes with an elongated shape and a bright white sclera background for a dark iris. Known as ‘cooperative eyes’, they invite anyone we interact with to easily construe what we are looking at. By contrast, all great apes have round, dark eyes, making it very difficult to identify from eye direction what they are looking at. The cooperative eye hypothesis was first proposed by Kobayashi and Kohshima and was subsequently tested by Michael Tomasello, whose research has elucidated the uniqueness of human social cognition.

Whereas staring into the eyes of other primates is considered threatening, our eyes are adapted for mutual mindreading, also known as intersubjectivity. To look into each other’s eyes, asking ‘can you see what I see?’ and ‘are you thinking what I am thinking?’ is completely natural to us, beginning from an early age.

Sarah Hrdy gives the most convincing account of how, why and when this happened. All human cultures practise mutual care, mothers being happy to hand over their offspring for others to look after temporarily. In stark contrast, great ape mothers—chimpanzees, bonobos, gorillas and orangutans—are hyper-possessive and protective due to the risks of harm to their infants and simply will not let go of their babies, not daring to take the chance.

This applies particularly to great apes; monkeys behave differently, being prepared to leave a baby with a trusted relative. The key factor involved is exactly how closely related individuals are: Old World monkey mothers usually live with their female relatives, while great ape mothers don’t. This means ape mothers have no one nearby whom they can trust sufficiently. This is telling us something significant about the social conditions in which we evolved, and Hrdy finds the key in the primatologically unique length of human childhood. If the young were to survive in a world of scarce food, they needed to be cared for, not only by their mothers but also by siblings, aunts, fathers, friends—and, with any luck, grandmothers.

Digging for tubers, a Hadza food staple. Photos by Katrin Redfern/Andrew Stern.

The ‘grandmother hypothesis’

The ‘grandmother hypothesis’ has been used to explain our extraordinarily long post-reproductive lifespans—the evolution of the menopause. Grandmothers would have had a big impact on a child’s survival, while also allowing the mother to begin the cycle of having her next baby. This has resulted in the special characteristic of ‘stacked’ families among humans, where—unlike other great apes—mothers can have several dependent offspring at once due to shortened birth intervals. Population geneticists are providing some confirmation of matrilocal tendencies as the underlying default for immediate-return African hunter-gatherer groups, supporting the grandmother hypothesis as an important evolutionary context.

Hrdy explores further how our uniquely prosocial shared intentionality can be traced back to the psychological changes involved in the evolution of cooperative breeding. While cooperative childcare may start with the mother-daughter relationship, bonding with grandchildren would quickly lead to the involvement of other trusted relatives. Within a few short hours after birth, a hunter-gatherer baby will have been held by numerous relatives and friends, of both sexes. From the moment when mothers allow others to hold their babies, says Hrdy, selection pressures for new kinds of mind-reading are established to enable this triad of mother, baby and helper to consolidate bonds while monitoring one another’s intentions. Cooperative breeding thus leads to a social structure that rewards prosocial behaviour, which in turn leads to changes in neural structure that enable the emergence of shared intentionality.

Our very large brain volumes are another feature that makes it clear our ancestors went through a prolonged phase of egalitarianism. While a human and chimp mother have a fairly similar body weight, adult humans today have upwards of three times the brain volume of a chimp. Brain tissue is very expensive in terms of energy requirements. Doing the childcare by themselves, great ape mothers are constrained in the amount of energy they can provide to offspring and so apes cannot expand brains above what is known as a ‘gray ceiling’ of 600 cc. Our ancestors smashed through this ceiling some 1.5-2 million years ago with the emergence of Homo erectus, who had brains more than twice the volume of chimps today. This tells us that cooperative childcare was already part of Homo erectus society, along with concomitant features of evolving cooperative eyes and emergent intersubjectivity.

We can track the degree of egalitarianism among descendants of Homo erectus, by measuring brain sizes in these early humans, using the fossil record. From 6-700,000 years ago we begin to see cranial values in the modern human range, three times as large as present day chimps. From half a million years ago, for both African (modern human ancestor) and Eurasian (Neanderthal ancestor) populations, brain size accelerates rapidly. What we find evidenced in the fossil record is materially more energy for females and their offspring. This implies an inevitable gendering of the strategies that enabled this to happen.

Most nonhuman primates that live in multi-male groups today exhibit a pattern of males forming a hierarchical power structure with a single alpha male at the apex. Male dominance and strategic control of females would not have lent itself well to procuring the caloric intake needed to produce such large brained babies. Those populations where male dominance, sexual conflict and infanticide risks remained high were not the ones who became our ancestors. We descended from those who somehow solved the problem of great ape male dominance, instead harnessing non-alpha males into routine support of these extraordinarily large-brained offspring.

Relatedly, female reproductive physiology provides another sign of our egalitarian origins. Female hominins’ reproductive signals of concealed and unpredictable ovulation coupled with continued sexual receptivity for virtually all of their cycle, a much larger proportion than any other primate, scrambles the information for males about exactly when a female is fertile. For a dominant male trying to manage a harem of females this is disastrous; he cannot monopolize the fertile moment and then move on to the next one (a classic strategy for dominant male apes). While he is guessing about the possible fertility of one cycling female, he has to stay with her, missing other opportunities. This in turn creates an opportunity for non-alpha males to mate with those other sexually receptive females. Continuous sexual receptivity thus spreads the reproductive opportunities around many males, hence is leveling from an evolutionary perspective. After all, for females needing higher caloric intake to birth those big-brained babies, it’s better to give reproductive rewards to males who will hang around and provide for mother and resulting offspring.

The stakes of survival

Cooperative breeding, grandmothers, cultural transmission, extensive cooperation between non-kin, food-sharing, intersubjectivity and social values define humans as much as large brains or bipedal stance. The foundations of these behaviours can certainly be found in our closest primate relatives. Yet during our evolution, cooperative relationships and the cognitive mechanisms which support them clearly became far more extensive. We are still left with all the biological and psychological evidence that our ancestors went through a prolonged phase of egalitarianism. Without it, we would not be here as language-speaking modern humans; a fundamentally egalitarian matrix is the only possible ground for the evolution of language.

Examining what makes our species unique can serve as a guide to what capabilities we wish to select for today. Humans are capable of a range of behaviour. We’re not born inherently moral; egalitarianism is a social choice, an evolutionary strategy that helped us to evolve beyond our primate cousins and enabled us to survive a harsh and dangerous world long enough to pass on our genes to the next generation, implying a gene-culture coevolution.

Crucially, we’re also capable of cooperation with our environment. Recent ethnobotanical and archaeological research in the Americas has shown that many landscapes deemed ‘wild’ by the earliest European explorers had already been modified and subtly managed by the indigenous peoples of those regions, often for many centuries. We now know that the rich diversity of the Amazonian rainforest, for example, is at least partly the result of small-scale horticultural practices enacted by indigenous cultures in the region for many thousands of years.

In this sense, egalitarianism is not a utopian ideal. It’s simply the other side of human nature that gets forgotten.


Katrin Redfern