What can chimpanzees teach us about human nature?

Chris Knight of the Radical Anthropology Group explores the relationship between sex, language and culture

Many Darwinians argue that humans are basically apes, who are rank-conscious and violent, and that is why we have rape, war, hierarchy and inequality. As Darwin argued, we must have evolved from a primate, chimp-like ancestor, so it is no surprise that we are genetically very close. And if you think genes determine behaviour then it makes sense to argue that you cannot change human nature, so socialism is an unworkable dream.

A good thing about Noam Chomsky is that he refutes all this, arguing that human nature is utterly different. The main difference, he says, is that we have language, which has been genetically installed. But then he goes to the other extreme, arguing that humans are so utterly different from apes or monkeys that the question of evolution is irrelevant.

If you ask Chomsky how language evolved he says simply that it did not. So what did happen? He talks about a cosmic ray shower which caused a mutation which instantaneously “installed” what is probably the most complex entity in the entire universe - the uniquely human language organ.1 This is not science, but a slightly disguised biblical miracle account of human origins.

My own ideas on this subject were originally inspired by what Frederick Engels had to say. He linked the origins of language with increased levels of social cooperation, focusing especially on sex. I quote from his preface to The origins of the family, private property and the state:

Here we see that animal societies are, after all, of some value for drawing conclusions about human societies; but the value is only negative. So far as our evidence goes, the higher vertebrates know only two forms of family - polygyny or separate couples; each form allows only one adult male, only one husband. The jealousy of the male, which both consolidates and isolates the family, sets the animal family in opposition to the herd. The jealousy of the males prevents the herd, the higher social form, from coming into existence, or weakens its cohesion, or breaks it up during the mating period; at best, it arrests its development.

Engels is pointing out that sex can be disruptive, and that neither language nor labour can have evolved until that basic problem was overcome. He continues:

This alone is sufficient proof that animal families and primitive human society are incompatible and that, when primitive men were working their way up from the animal creation, they either had no family at all or a form that does not occur among animals. In small numbers, an animal so defenceless as evolving man might struggle along even in conditions of isolation, with no higher social grouping than the single male and female pair, such as Westermarck, following the reports of hunters, attributes to the gorillas and the chimpanzees.

For man’s development beyond the level of the animals, for the achievement of the greatest advance nature can show, something more was needed: the power of defence lacking to the individual had to be made good by the united strength and cooperation of the herd. To explain the transition to humanity from conditions such as those in which the anthropoid apes live today would be quite impossible; it looks much more as if these apes had strayed off the line of evolution and were gradually dying out, or at least degenerating. That alone is sufficient ground for rejecting all attempts to draw parallels between animal forms of family and those of primitive man.

And this is the key point:

Mutual toleration among the adult males, freedom from jealousy, was the first condition for the formation of larger groups, in which alone animals could become men.2

Engels is clearly saying that even so powerful an instinct as sexual jealousy can be transcended if the right conditions are established through collective action.

Human nature

Note that Engels is not denying the obvious fact that human nature exists. It is sometimes imagined that Marxism is a ‘blank slate’ philosophy, the idea being that a baby is born without any innate dispositions and that, in growing up, it can be moulded by culture anyway. But that philosophy is behaviourism, not Marxism.

The behaviourist view that there is ‘no such thing as human nature’ was prevalent in the 1930s and 40s within the USSR and the west. Essentially it said that humans are malleable and you can do what you like with them. It held that through punishments and rewards people’s behaviour could be changed, as if they were laboratory rats trained to navigate through a maze. Chomsky pointed out that any bureaucrat in the Soviet Union or in the US would love this idea, because it means you could make people happy on the production line, you could do what you wanted to them. I agree with Chomsky that this view of human nature as infinitely malleable is an extremely oppressive, convenient myth.

Marx, in the Economic and philosophic manuscripts, talks about what alienation means in relation to the worker under capitalism:

Labour is exterior to the worker: that is, it does not belong to his essence ... he does not confirm himself in his work: he denies himself, feels miserable instead of happy, deploys no free physical and intellectual energy, but mortifies his body and ruins his mind. Thus the worker only feels a stranger.3

None of this makes any sense except on the assumption that non-alienated labour - labour which corresponds to the ‘human essence’ - is theoretically possible as an alternative.

Marx had a quite definite conception of human nature, conceiving it as intrinsically social. We all know intuitively that this is right. Humans feel healthiest and happiest when relaxing among equals, taking orders from no-one, being free to play, laugh and sing together, as hunter-gatherers still do to this day. To be human, from this standpoint, is to be on speaking terms with one another. This means allowing one another a certain kind of freedom - freedom to joke, to laugh, to make fun of one another, to signal in ways not literally true, to allow a gap between what our words literally say and what we intend them to mean. Without such freedom, no part of language could even begin to evolve.

In his Fragments of an anarchist anthropology and other works, David Graeber makes the important point that, deep down, we are all communists in that sense. Capitalism sponges off our ability to be creative, imaginative and playful; its own top-down, competitive logic is the death of all this, but luckily it leaves sufficient gaps for us to take the creative steps, without which nothing would work.

I like this idea. All of us know what kind of relationships make us happy. We find it hard to deal with relationships of dominance and submission - it can be very hard to joke and be honest with your boss. Comfortable, relaxed relationships depend on mutuality and this is evidence that we evolved under conditions of social egalitarianism. That is very different from the Darwinian idea that we are simply clever apes, whose mental qualities differ in quantity, but not in kind, from other apes.

I noted just now that, for Engels, theories about human origins made no sense if they ignored sexual differences and treated everyone as male. While it is true that we still get one-sided theories about ‘man, the hunter’, ‘man, the toolmaker’ and so forth, this fundamental point is today widely acknowledged. If we take a book like Primate social systems by Robin Dunbar - one of the most authoritative primatologists - it essentially uses a methodology that Marxists would recognise. Reflecting a widespread scientific consensus, Dunbar argues that changes within primate social systems always stem initially from choices made by females.

Why is that? It is because the females alone have responsibility for offspring, so they choose where to move, according to where the food is. Meanwhile, the males have quite different priorities, since they want to find fertile females. This means it is the females whose choices determine everything else.

To take an example, one can look at bonobos and chimps. Chimp societies are male-dominated, but one species of chimp, the bonobo, lives in female-dominated groups. How do you explain that? There is a materialist explanation, with a focus on the digestive system. If you can eat grass, which grows everywhere, the females can clump together; if you eat fruit, which is more dispersed, the females will be more dispersed. Depending on the distribution of females, male apes will or will not be able to monopolise a group of them. In the case of bonobos, females in the same area form a sexual bond through rubbing each other’s genitals and, if faced with competition for food by male bonobos, they will jointly chase off that male. Bonobo females have even been known to hunt together, fighting off any males who seek to steal the meat.

Bonobos live near a bend on the south side of the Congo river - north of the river are male-dominated chimpanzees. How has this come about? One materialist theory says that the chimps on the north side have to compete with gorillas for food, meaning the chimpanzee females disperse and therefore lack solidarity, so the males can dominate them. Bonobo females south of the river, where there are no gorillas, can afford to live more closely together, allowing them to form coalitions that prevent male dominance. This explanation sees chimp behaviour driven not by the mind or by genes (which follow behaviour rather than lead it), but by the means through which these apes forage and sustain themselves.

Primates and humans

As demonstrated in the earlier quotation, Engels was not scared of talking about sex, and neither should we be. From the size of the testicles of a primate male it is possible to make inferences as to the mating system. For example, chimpanzees have very large testicles, whereas those of baboons are quite small. Chimpanzees need such large testicles because, when a male has sex, most likely another male has had sex with that same female first, so the male needs especially strong sperm, and lots of it. If you are a baboon male you need to fight off other males and monopolise a harem, using your claws and teeth. The females in your harem do not have access to other males, so you do not need especially large testicles.

We can apply this to human evolutionary biology. Human males have testicles of a size roughly between those of baboons and chimpanzees. This tells us that in our evolutionary past, when we were all hunter-gatherers, humans were not particularly monogamous, but neither were they strongly promiscuous. This fits with what we know of sexual arrangements in hunter-gatherer societies. There is not strict monogamy. People will pair up and be relatively faithful, with extra-marital sex occurring sometimes during ceremonies, but there is no reason why these pairs have to stay permanently together. Often a woman in these societies will find a new sexual partner after weaning her first child.

The length of the menstrual cycle in different species can also tell us a lot about corresponding mating systems. Bonobos have a 40-day cycle, while for chimpanzees it is 36 days. Humans on average have a 29.5-day cycle. This just happens to correspond to the length of time it takes for the moon to pass through its phases, as seen from the earth. This makes it the only one that is the length you would predict if there had been some reason in humanity’s evolutionary past to synchronise with the moon.

Chimpanzees could not synchronise their menstrual cycles with the moon even if they wanted to - 36 days is just the wrong length. Chimpanzees live under closed canopy forest, meaning they do not see much of the moon. Humans, by contrast, evolved in open landscapes, where the moon makes a big difference to life after dark. From early in the Pleistocene period, our hominin ancestors evolved alongside various species of big cat, including lions, whose excellent night vision makes them prefer to hunt on dark nights, when there is no moon. It is not hard to see that an awareness of lunar cycles in our case would have been a matter of life and death.

Eyes are another bodily feature that have an effect on behaviour and provide us with insight into human nature. In primates such as chimpanzees or gorillas, adults have dark eyes, plus dark skin around the eyes, making it difficult to tell where they are looking. These apes in their competitive world need to look without reciprocally allowing others to tell what they might be looking at or thinking. In that sense, they have one-way eyes. Humans, on the other hand, have two-way eyes - eyes with a dark iris set against a bright, white background. It is as if they were especially designed to tell others what we are thinking. When talking to each other, we use eye contact: our eyes are mutually, cognitively transparent.


The eyes play an important role in human infancy and early childhood. A major figure in this field is evolutionary psychologist Michael Tomasello, who has spent his life studying the differences between the ape mind and its human counterpart. One reason his work has been so fruitful is that it is inspired by the great Soviet child development pioneer, Lev Vygotsky, who was emphatically a Marxist.

Tomasello describes what happens to a human child from about the age of one year, when it undergoes what he terms a “cognitive revolution”. This occurs at the point when the child does something no chimp will ever do - see itself from the standpoint of others. Chimpanzees never escape the ego, never manage to see themselves as others see them. Egocentric perspective reversal is a crucial prerequisite of linguistic communication, and its absence in apes helps explain why language in their case cannot even begin to evolve.

Sometimes it is argued that apes do not have language because they have an inflexible tongue, or because they are cognitively deficient. But there is a much more convincing explanation. Language is only possible for a creature that lives cooperatively in a way that transcends the competitive logic of primate social life.

Tomasello’s basic point is that if chimpanzees do not have language, it is for the same reason they do not have cooperative eyes. By instinct, they are incorrigibly suspicious and competitive. If you take two buckets, one containing hidden bananas and one without, and you helpfully indicate to a chimpanzee which one has the bananas, it will immediately rush to the wrong bucket. It operates on the assumption that it is a trick - which it would be for chimpanzees interacting among themselves in the wild. It just cannot believe that you are being cooperative. Tomasello showed that the only way you can get the chimpanzee to understand where the bananas are is by reaching toward the correct bucket yourself, as if trying to corner all the bananas to eat them - which is what any chimp would certainly do.

When responding to signals, apes prefer direct sensory evidence over unverifiable claims. The easier it is to manipulate the signal, the lower its chances of being accepted as either reliable or worth responding to - and so the less likely it is to evolve. To be safe, non-human primates respond preferentially to body language which cannot be manipulated or faked. Like the watermark in a banknote, in other words, the relative inflexibility of primate vocal signalling, far from being a maladaptive trait or a deficiency, has positive value. It is how apes and monkeys assure one another that their signals are not fabrications, not dishonest fakes.

Apart from the hand, the tongue is the most sensitively flexible, controllable organ in the body. It may seem paradoxical, but that is precisely why apes do not involve the tongue at all when producing a scream or cry. Chimpanzees in the wild do not even use their fingers or hands to point things out to one another: they are too selfish. The closest to pointing among chimpanzees is the so-called ‘directed scratch’. When two chimps are grooming each other, the one being groomed may point to a spot it wants scratched. So it is not that they are incapable of pointing: they simply do not see the purpose of pointing for the benefit of someone else.

In the wild, chimps may hunt together - they often hunt colobus monkeys - but each one is calculating, ‘How do I get the meat?’ There is no obligation to share it out after the hunt, as there always is when hunter-gatherers bring back meat to camp. In the chimp case, it is a free-for-all. The most dominant animals grab the most, leaving the females to beg. Those females who are pregnant or nursing are unlikely to get much at all. In fact, it is when we look at sexual politics that we see most starkly the contrast between ape reproductive strategies and those which our own ancestors must have pursued.

Culture and sex

Leading social anthropologist Marshall Sahlins wrote long ago about sex in monkeys, primates and early humans. His words echo those of Engels and I think he got it right:

Sex is not an unmitigated social blessing for primates. Competition over partners, for example, can lead to vicious, even fatal, strife. It was this side of primate sexuality that forced early culture to curb and repress it. Cooperation, not competition, was essential. Culture thus brought primate sexuality under control. More than that, sex was made subject to regulations, such as the incest taboo, which effectively enlisted it in the service of cooperative kin relations.

Among subhuman primates sex had organised society; the customs of hunters and gatherers testify eloquently that now society was to organise sex - in the interest of the economic adaptation of the group. In selective adaptation to the perils of the Stone Age, human society overcame or subordinated such primate propensities as selfishness, indiscriminate sexuality, dominance and brute competition. It substituted kinship and cooperation for conflict, placed solidarity over sex, morality over might. In its earliest days it accomplished the greatest reform in history - the overthrow of human primate nature - and thereby secured the evolutionary future of the species.4

The part which is missing from Sahlins’ account is the active role of females in this revolutionary overthrow. When chimpanzees have violent conflicts, it is almost always the females who feel most threatened and who band together to do something about it. Frans De Waal provides an example observed in a large enclosure, where a dominant male called Jimoh had noticed that one of his subordinates, Socko, was having sex with one of his females:

Jimoh went full speed after Socko and did not give up. He chased him all around the enclosure - Socko screaming and defecating in fear. Before Jimoh could accomplish his aim, several females close to the scene began to ‘woaow’ bark. This indignant sound is used in protest of aggressors and intruders. At first the callers looked around to see how the rest of the group was reacting, but when others joined in, particularly the top-ranking female, the intensity of their calls quickly increased, until literally everyone’s voice was part of a deafening chorus. The scattered beginning almost gave the impression that the group was taking a vote. Jimoh broke off his attack with a nervous grin on his face: he got the message. If he had failed to respond there would no doubt have been concerted female action to end the disturbance.5

This is an example of collective resistance to dominance, often termed counter-dominance. Where you have dominance, there will be resistance - no animal really likes to be dominated, although they can adapt to it. If Sahlins is right that primate dominance was somehow overthrown, it surely makes more sense to attribute this to collective female resistance than to ‘culture’ in the abstract, as Sahlins does.

The process starts with humans living in relatively large groups, placing pressure on the brain to get bigger in order to cope with the increased complexities of social life. Large brains are costly and it is going to be the females who initially have to pay the costs in terms of pregnancy, nursing and childcare. In order to meet those costs of bringing up babies with large, slowly maturing brains, mothers needed extra help. Males would not have been of any use at first, so childcare would have been shared around the females, initially with mothers and sisters. Then eventually these bonds of mother-daughter and sister-sister solidarity would have been used to coax the males to help with provisioning and do something useful for a change, instead of fighting for sex.

If you do not incorporate some version of the battle of the sexes in your theory of origins, you will probably end up resorting to the only logical alternative, which is the notion of hunter-gatherer groups waging war against each other for access to scarce resources. Unfortunately, even Michael Tomasello himself tends to favour the warfare theory. There is a case for this, in that primates do not form coalitions except in resistance to some threat. But the key thing with the sex war is that, if you are a male, it might actually be in your interest, at a certain point, to lose that war. The Darwinian reasoning here is simple: if you are a male and the females win, it may be your own offspring who then benefit. In other words, sexual conflict is the one kind of ‘war’ in which the normally dominant side - the sex with the greatest capacity for violence - might actually have an interest in losing.

In that quotation from Frans De Waal, the chorus of chimpanzee ‘woaow’ barks is the unmistakable sound of female collective disapproval. It is not quite what humans would interpret as derisive, hostile laughter. But it is not that far off. Human laughter, too, can come close to being hostile. It is actually best conceptualised as vocal mobbing under reversed conditions, once the threat which initially provoked it has collapsed. A similar logic of reversal applies to the human smile. Among chimpanzees, the nearest they get to a smile is when they bare their teeth in fear: they are frightened and trying to threaten their opponent. Now imagine the threat suddenly disappears. What remains of the fear-grin will now become relaxed, expressing not fear, but relief - which seems to be the origin of the human smile.

There seems to be a link between smiling, laughter and singing - all uniquely human capacities. It is even possible that human choral singing evolved initially from something like choral mobbing. Backing up this idea, Jerome Lewis once asked some Ba Yaka pygmy women, “Why do you sing?” The women said they were singing for their lives. They said when the moon is dark there are all kinds of dangerous animals out there and “We sing to scare them away”.

Lewis points out that the Ba Yaka women’s own explanation for their singing fits well with what scientists now know about human origins. Although singing together is enjoyable in itself, there is a deeper reason why women do this together: they really are singing to keep safe - “singing for their lives”. According to Lewis, the particular kind of choral singing which is practised by these people conveys to potential predators a ‘Don’t mess with us’ message, magnifying the impression of a large and well-organised group. He believes that, once female coalitions had discovered their power to deploy synchronised chorusing to deter animal predators, it was only a small step to extending laughter and singing to coax lazy or badly behaving human males to improve their behaviour. Spoken language would have been a later development, made possible by new conditions of social cooperation and public trust.6

There is a lesson in all this. There is such a thing as human nature, but that does not mean we are basically chimpanzees. Our nature has been transformed over the past few million years, and certainly changed fundamentally as our own species - Homo sapiens - evolved some 200,000 or 150,000 years ago. The social changes responsible for transforming our nature were so massive as to merit the term ‘revolution’.

We did it once: we can do it again.


1. N Chomsky The architecture of language Oxford 2000, p4.

2. www.marxists.org/archive/marx/works/1884/origin-family/ch02.htm.

3. www.marxists.org/archive/marx/works/1844/manuscripts/labour.htm.

4. M Sahlins, ‘The origin of society’ Scientific American 203(3) 1960, pp76-87.

5. F de Waal Good-natured: the origins of right and wrong in humans and other animals Cambridge MA 1996, pp91-92.

6. See C Knight and J Lewis, ‘Vocal deception, laughter and the linguistic significance of reverse dominance’, in D Dor, C Knight and J Lewis (eds) The social origins of language Oxford 2014, pp297-314.