Human see, human do

'The Primate Myth' by Jonathan Leaf

Human evolution has always fascinated me, in particular its effect on human behaviour today, but I’m as far from being an expert as is possible. So this is not a review as such, but rather an overview of a fascinating new book, The Primate Myth by Jonathan Leaf. I found it highly entertaining as well as informative.

Leaf argues that humans shouldn’t be understood as members of the ape family, and our relatedness to chimps and gorillas is vastly overstated. If we want to know human nature, he writes, it is more valuable to study the behaviour of elephants, dolphins, whales, dogs, rats and even ants.

Inspired by the work of primatologists, in recent years there has been a trend towards viewing the great apes as almost quasi-human. Peter Singer and Richard Dawkins suggested they be treated as ‘non-human persons’ and granted the same rights as people. This proposal was backed by Spain and then the European Union, which banned further research on apes except in emergencies. As Leaf writes, ‘the idea seems to be that as chimps and gorillas are our brothers and sisters, and as they have never placed their signatures on any piece of paper accepting experimentation upon them, it ought never to occur.’

Yet mankind’s ancient primate ancestry is not what makes us unique or interesting: it’s the particular path our forebears took after they diverged, which makes us more similar to other highly social species like dolphins and dogs. Even the common trope that humans and chimps share between 98-99 per cent of DNA is based on ‘a somewhat debatable method of counting’, he argues.

Our ancestors were physically weak primates who, forced out of the trees by a changing climate, found themselves extremely vulnerable on the ground: they survived by carving out a niche as highly co-operative hunters, making our species unusually social, indeed almost eusocial.

Mammals don’t generally kill themselves or sacrifice the opportunity of reproduction for the good of the nest. Primates certainly don’t. It’s what makes us unique, both for good and evil, incredibly susceptible to the influence of the group and its high-status members. We are notably tame and also capable of committing the most appalling atrocities – driven by a sense of loyalty, love and empathy. Reading this book, I couldn’t help but be reminded that the two most docile and civilised nations on earth, the Germans and Japanese, were responsible for the most appalling cruelty during the last century. And that’s not a coincidence.

Primatologists have long been aware that chimpanzees are slow learners, far less adept than dogs, and they also score badly at pattern-recognition tests, no better than monkeys and even chickens. They are also notably uncooperative with members of their own species, failing to help them in experiments even when there are no costs to themselves. More disturbing, if one sees these creatures as our kin, is the fact that apes are incredibly violent, and ‘one government study found that more than two-fifths of all primatologists report that they have been bitten.’

In 1975 ‘Jane Goodall returned to Tanzania from a brief trip to England,’ when one of her aides told her about a chimp who had gone on a cannibalistic killing spree. ‘Soon after Goodall’s book came out, her researchers observed two males that attacked females from outside their troop, stole their babies, tore the infants to shreds and digested them. More remarkable still was that cannibalistic mother-daughter team, known as Passion and Pom. Working side by side, they captured, killed, and consumed something in the range of ten chimp babies.

‘Overall, a study of the work of chimp researchers in Africa found that through 426 years of observations they had uncovered 152 chimp killings, 58 of those they witnessed with their own eyes… Over time, the chimps’ terrain becomes a marking ground for corpses.’

Somewhat less violent are bonobos (Pan paniscus), who are either a subspecies or different species closely related to the common chimpanzee (Pan troglodyte). The two groups split between 1.5 and 2 million years ago, divided by the Congo River, and while there are some differences in diet and physique, they are very similar. There was a common idea when I was younger that bonobos were into peace and love, because they are less aggressive than their close relatives and seem to spend much of their time having orgies, but their resemblance to a Flower Power-era commune rather ends there.

As Leaf writes, ‘Bonobos “wake up ready for a fight.” They are one hundred times as likely as people to engage in physical violence. You can get a sense for what their nature is by examining the best practices recommended for zoos where they are kept. Bonobos need to be separated from people by 5-meter-high fences (16.4 feet), and they are not under any circumstances to be given open access to roofs - even when they are in their own spaces apart from zoo visitors.

‘Alternatively, a standard handbook recommends that around their dwelling areas water-filled moats be built. These are to be at least 23 feet wide and 5 feet deep. This is for a creature that cannot swim. Beyond this, secondary fences are recommended. These may be electrified. There are many more pages on the arrangement of secure areas in which bonobos can be placed when they are in conflict. These call for more fences along with steel locks for doors, iron mesh, and other impediments designed to keep them at an appropriate remove. By contrast, the fence height suggested for cheetahs is 2.5 meters (8 feet), and no moats are required. Those who toil with bonobos know that they are far more dangerous than big cats.’

Humans, in contrast, do not even rank in the top 30 of species who kill their own kind, despite the toll of wars. One reason for this relative docility is that our brains have evolved a strong sense of empathy towards other humans, and with it a revulsion to taking innocent life.

While chimp brains are smaller than ours, the difference is uneven, with particular areas of the human organ far more enlarged, in particular the Broca region. This influences our ability to phrase words, as you’d expect, and is also close to the anterior cingulate gyrus, which affects our abilities to plan and learn from mistakes; he notes that ‘criminals with poor function in the rear of the cingulate gyrus are more prone to recidivism’. Most tellingly, though ‘there is a correlation between the size of the anterior cingulate gyrus and the capacity for empathy’. It is generally larger in women, who possess more empathy on average, and far smaller in psychopaths: ‘All this leads us to one conclusion: When people lack for empathy, they have brains in which the cingulate gyrus is like that of a chimp or gorilla.’

We are not alone in possessing an enlarged anterior cingulate gyrus: rats are similar. Leaf writes how researchers at the Netherlands Institute for Neuroscience conducted an experiment with the rodents by offering them sweets in exchange for pulling a lever in their cage.

‘Then they shocked the foot of a rat in an adjoining cage when a rat asked for his treat. That caused the shocked rats to squeak in pain. The Dutch scientists noticed that some of the first group of rats, distressed by what they saw, stopped pulling the lever and asking for candy. However, when the researchers anesthetized the rats’ anterior cingulate gyrus, preventing it from operating, all the rats went on requesting their sugar-sweetened snack. Without a functioning anterior cingulate gyrus, they no longer cared when they observed other rats in torment.’

Rats hate to see other rats suffer, even strangers, and in that way they are very much like humans, but unlike gorillas or chimps. This makes sense when one considers that both rats and homo sapien are very vulnerable as individuals, require the protection of large colonies, and so have evolved to care about other members of their species.

Leaf writes of rats that ‘as they are not herd animals, they cannot group together and ward off predators with the danger of a stampede. Nor do they have a porcupine’s quills, a snake’s poisonous bite, a chameleon’s gift for protective coloration, or a skunk’s attack of stench. Small and weak yet continually exposed, they must learn to work together to ward off strikes by larger predators.’ The same, of course, was true of us in our ancestral home on the savanna

‘As we diverged in our evolution from chimps, we moved onto the path of all other large-brained mammals with a highly developed cerebral cortex: We became much more socially aware. This is consistent with our observation that dogs can learn more words than chimps. A more social creature - in this case, a pack rather than a herd animal - has greater language skills than a more egocentric animal, a primate, though the latter is possessed of a larger brain.’ Even within our species, ‘people who master languages and accents easily tend to be more aware of their peers’ feelings and are more socially adept. They blend in better. Their voices sound more like their neighbours. They stand out less.’

We might be in some ways closer even to ants than chimps. The author cites famed entomologist E. O. Wilson – one of the first victims of cancel culture – who wrote that ’ants are the most warlike of all animals, with colony pitted most violently against colony of the same species. Extermination is the goal for most, and as a rule larger colonies defeat smaller ones. Their clashes dwarf Waterloo and Gettysburg.’ Leaf writes that ‘This makes sense as ants are obedient, collaborative, and social to a degree that far exceeds humans, and war is an activity of biddable and cooperative creatures.’

Human obedience, similarly, is what drives our worst violence. Most will know about the Milgram experiment, which showed that people are willing to inflict even fatal pain on strangers if told by an authority figure, ‘yet one of the most striking findings of the Milgram experiments garners relatively little attention. When Milgram asked the volunteers whom he brought in to form into groups of three and direct the research themselves, not one person went ahead and placed the high-voltage shocks on the actor playing the part of the test subject. It was only when a guiding authority figure instructed the volunteers to engage in torture that people did so.’

Most people are instinctively repulsed at the idea of inflicting pain on other humans, and the small number who don’t have this instinct we label as defective or sick. Indeed, a psychopath is regarded as the worst kind of monster because he lacks the essential quality that makes us human - and by this measurement, all chimps are psychopaths.

One reason for lower levels of human aggression, as well as our greater skill at planning, is that, like dolphins, we have evolved to mature much slower - and because of our delayed life cycle, infants are vulnerable for much longer. Since paternal support hugely raises the chance of survival, humans have evolved to be more monogamous than apes, and globally ‘polygamy is consistently associated with familial strife and haphazard parenting.’ With pair bonding comes the incredibly powerful and dangerous force of male sexual jealousy; in contrast, in both types of chimps females in season will have sex as much as 50 times with eight males over the course of a day. Lots of love, but not much peace.

It was Wilson, along with Sarah Blaffer Hrdy, who ‘did the most to undermine the belief that our species could be readily understood through observation of chimps and gorillas.’ Wilson ‘in his final years… came to argue that the salient characteristic about humans was not our kinship with apes. He instead emphasized our capacity and instinct for cooperation.’

In 2010 Wilson made the connection more explicit in an article noting the similarities in behaviour among our species and various insects: ‘Some solitary bee species placed in lab settings naturally set to work with other bees. This is to say that they appear to be genetically inclined - programmed - to assist bees they are unrelated to.’ He ‘suggested that the rise of humans might be similar: Our ascent might be founded in a comparable and equally rare yet innate impulse toward empathetic collaboration.’

Wilson’s ‘idea was not welcomed in academia’ Leaf notes. ‘The source of the anger it provoked was especially to be seen coming from one clan: the primatologists. Assisting one another, showing a strong cooperative impulse, they attacked the belief that humans naturally form up into collaborative groups. The irony, it seems, was lost on them.’

‘I hate every ape I see/From chimpan-a to chimpan-z’

The ancestors of humans, forced down from the trees, had to hunt for food despite being singularly unsuited towards hunting, possessing teeth one-seventh as strong as hyenas. Their evolutionary survival depended on an ability to co-operate, and a strong sense of altruism, something shared with cetaceans - aquatic mammals - who are similarly vulnerable in the ocean and must stick together or perish.

‘This would explain why dolphins are especially known for their altruistic deeds. Cetacean researchers have noticed that dolphins will aid injured companions by pushing them to the surface so they can swallow air. In other cases, dolphins have helped beached whales get back into the ocean, and they have formed circles to protect people from sharks. These actions placed the dolphins at risk for their own lives. They are behaving as we do when we put ourselves in jeopardy, whether to save human lives or those of other animals.’

In the words of Jane Goodall, ‘I cannot conceive of chimpanzees developing emotion, one for another, comparable in any way, to the tenderness, protectiveness, tolerance, and spiritual exhilaration that are the hallmarks of human love in its truest and deepest sense. Chimpanzees usually show a lack of consideration for each other’s feelings which in some ways may represent the deepest part of the gulf between us and them. For the male and female chimpanzee there can be no exquisite awareness of each other’s body - let alone each other’s mind. The most the female can expect is a brief courtship display, a sexual contact lasting at most half a minute, and sometimes, a session of social grooming afterward. Not for them the romance, the mystery, the boundless joys of human love.’

To be fair, it’s probably hard to have too much romance when there are seven other guys waiting their turn.

Because of our relative weakness as individuals, humans are deeply attuned to public opinion. Very few people genuinely don’t care what others think about them, however much they protest to the contrary. Public shaming and loss of face is therefore terrifying to us, the proverbial fate worse than death.

Leaf notes how humans develop a high risk of suicide following incidents which might result in disgrace, whether being arrested on even minor charges or the slightest of adolescent setbacks. ‘The overwhelming majority of those who kill themselves were not suicidal before their arrest and were not in ill health. Rather, the sense of terror, failure, and the worry about what others will think of them afterwards cause them to commit suicide.’ Likewise, young women will starve themselves to death out of fear they fail society’s beauty standards, and ‘all these actions are proof of how our identity is bound up with concerns about how we are perceived by others.’

In contrast, ‘an ape’s identity is not so bound up with what others in the group think… In a number of critical ways humans appear to be unlike apes but akin to herd and pack animals.’ Indeed, he notes the irony of the verb ‘to ape’, because ‘while awkwardness in imitation may be an attribute of apes, mimicry and copying are human impulses far more than primate ones. Primates are much more likely to be oblivious or indifferent to the gestures of their peers. We doggedly obey fashion trends. They cannot even follow one another in any sort of line, straight or crooked.’

While unlike apes, our similarities to dolphins are so strong that, not only can we train these docile animals to perform tricks for food, ‘we may watch this and feel shame, seeing it as unworthy of them and unjust,’ showing ‘that we are in some measure alike. This mutuality animates our common impulse toward self-destruction and our common search for identity.’

Indeed these similarities can be unsettling: ‘A team of researchers who looked at nineteen dolphins that stranded themselves in Ireland in 1997 found that only one was ill. It seems that the rest followed the sick dolphin to shore. Reflecting on this, science writer Laurel Braitman observed: “No other group of mammals has evolved in a space so devoid of spots to hide from predators. Dolphins and whales don’t retreat to dens and burrows; they don’t climb trees or hide in caves. In the face of danger, they are able to hide only behind one another. This may have affected their social worlds, making their ability to trust, communicate, and cooperate with one another even more important. This may also explain why some strandings include otherwise healthy individuals. These healthy dolphins and whales may strand simply because their social bonds with their ailing fellows are too powerful to allow them to swim away.”’

Humans have the same tendency, not just in the extreme cases of mass suicide, but by following obviously dysfunctional behaviours and beliefs if higher ranking individuals signal their support. (Celebrity suicides, famously, are often followed by upsurges in people taking their own lives.)

While chimp and gorilla hierarchies are based on brute strength, ‘insofar as herd animals have hierarchies, they are based on social awareness and social skill. This is another proof, of course, that we are not primates. But it carries a further implication. Researchers who were interested in seeing which goats were best at investigating and solving a problem - finding food that had been hidden - observed that the ones who excelled at this tended to be worse at relating to other goats, and they ranked lower within their herd. They were the “outsiders.”’

The parallel with our own species is hard to avoid: we are herd animals, and ‘herd creatures adopt the outlook of those around them. They have a strong instinct to follow. As highly social and socially aware animals, we are obligated to. This is why humans are capable of joining cults and of killing ourselves or others on their behalf. It is why we will end our lives to advance the group, or, because we are capable of deep shame, we will commit suicide if we imagine that we have failed to live up to our sense of what we believe our friends and family expect of us.

‘We build giant temples as a part of a collectivity in order to share in a common faith and devotion and to blend in with and placate those who are most devoted. At the same time, we are obsessed with status, and we wear clothes not merely to make ourselves sexually desirable but to indicate our identity within a group and our sophistication and rank. We decide matters by election, and we conclude that the opinion of the collective is a profound form of validation. We tell ourselves that things are true because others believe them.’

Worst of all, we will come to hate, ostracise and even kill those who disagree and disbelieve. That, alas, is simply our nature as herd animals.