A Conversation with Robin Dunbar
Edited by Henry O'Connell and Gurjot Brar
First and foremost, thank you Robin for agreeing to take part in this interview. It is an amazing privilege for us to be able to ask you some questions for our Substack.
Gurjot and I first bonded over your 2022 book on religion (‘How Religion Evolved: And Why it Endures’) and we wrote a deservedly glowing review of it that was published in the British Journal of Psychology. So, your work has been instrumental in getting our collaboration going and, indirectly, this very Substack.
Onto our first question, did you ever think when researching primates back in the 1970s that you would jump to humans and end up writing about topics such as religion? Or was there a career plan all along?
“The simple answer is no, on both counts. Until the late 1980s, I regarded myself as a wildlife biologist as much as anything. Though I started out as a psychologist (and was rejected from clinical training for having done too much research on animals even as an undergraduate….). I was seduced by the opportunity to study animals in the wild, which is what I then did for my PhD and postdocs. Money for fieldwork in far off lands was very scarce in the 1980s, and studying humans ”in the street” seemed an obvious solution. Even so, it was really only after the discovery of the social brain relationship in 1992 that humans became a serious preoccupation. But having said that, perhaps there was all along a hidden germ somewhere pointing me towards humans. I grew up in a remarkably multicultural environment in East Africa and was deeply immersed in an extraordinary variety of different tribal and ethnic cultures at first hand. Inevitably, the how’s and why’s and the histories of all these fascinated me. Later, my PhD supervisor had, in the course of his career, transitioned from ornithology to primates and finally into humans, where the influence of Buddhism on Himalayan societies had captured his interest.”
In that recent book on religion, you appear to come down on the side of religion as ‘adaptation’ rather than ‘by-product’.
Is that a fair reading of your work? If so, what implications does that have on the understanding of human psychology at the individual and group levels?
And what implications does this have on human well-being in a future world with a much attenuated presence of religion in human affairs?
“I think there is no doubt that religion is an adaptation – if only because of the amount of time, effort and money humans devote to it. Evolution isn’t so profligate that it tolerates such high levels of maladaptive behaviour. If it was just a handful of people in one obscure culture somewhere, maybe; but not something that has such wide prevalence over the whole of recorded history. In my view, those who have argued that it is a maladaptive by-product have a rather narrow view of natural selection and the processes of evolution. One important lesson we have learned in the past half century is that sociality (living in groups) has been a crucial evolutionary development, especially in the primates who have taken this to very high levels. Solving the problems of survival and reproduction socially, rather than just individually, has been the secret of primate and human evolutionary success. That requires cooperation, and that in turn means we need mechanisms for engineering social cohesion. Religion has been one of the seminal ways of doing this. It’s principal evolutionary benefit has not been direct personal advantage, but indirect fitness at the personal level achieved by engineering effective the cohesion of social groups.”
We note from reading about your educational background that Tinbergen was one of your early teachers. That must have been something, where do you place him in the world of evolution?
“One of the peculiarities of the Oxford psychology course in the 1960s was that most of the first year was taught by Tinbergen (with contributions from a very young Richard Dawkins, just arrived back from a postdoc in America). It was dutifully entitled “Comparative Psychology”, but was in fact ethology. Tinbergen was, of course, very formative in the development of ethology from a casual amateur interest to a serious science. His emphasis on doing experiments based on very close observation of what animals actually did in the wild played a seminal role in the development of the field. And, of course, earned him a richly deserved Nobel Prize. That said, when I went to see him after my final exams about doing a PhD in his lab, he looked aghast when I said I was a psychologist and flatly refused to consider me further – notwithstanding the fact that I had already done two lengthy summer expeditions studying wild baboons in different parts of Africa!! Ah well – an opportunity lost is an opportunity gained somewhere else!”
You were one of the early proponents of the Social Brain Theory which has considerable face validity.
However, its initial promise in psychiatry has not led to a sustained research program nor to further major insights into mental disorder.
Is that a fair observation? If so, what are your current views on its relevance to mental health?
“You are absolutely right: the social brain theory might have seemed very relevant to psychiatry (we are, after all, very social beings), but there was nothing in it that relates to individual lives and the ways in which these might break down. That has, however, changed slowly over the last two decades as we have unpacked the mechanisms that underpin the social brain effect. Two features have emerged as important.”
“One is that the social brain is not really about groups per se, but about relationships. Social groups are an emergent property of our capacity to create functional relationships at the dyadic level. Over the last decade or so, there has been a veritable deluge of epidemiological studies showing that the single best predictor of our mental health and wellbeing, and even our physical health and wellbeing, is the number and quality of close family and friend relationships we have, with five being the optimum. Having too few or too many close friends leaves you vulnerable to depression, and that suppresses the immune system and leaves you vulnerable to physical ailments (including both vulnerability to viruses and slower recovery from injuries). There is now even a large number of studies of wild primates, wild horses and dolphins showing exactly the same effect. Having friends directly affects your evolutionary fitness.”
“The second feature has been all the work we have done trying to understand just what the nature of the glue is that binds friends together. The endorphin system turns out to be critical. And two of the happy by-products of endorphins are that, as opioids, they are the best anti-depressants you can get (weight for weight, they are 30 times more powerful as analgesics than morphine, and they aren’t chemically addictive) and, directly or indirectly, they upregulate the immune system (especially the natural killer cells). There is growing evidence that abnormalities in endorphin activation are involved in some classic psychiatric conditions, including autism and some personality disorders.”
Over the last decade or so, there has been a veritable deluge of epidemiological studies showing that the single best predictor of our mental health and wellbeing, and even our physical health and wellbeing, is the number and quality of close family and friend relationships we have, with five being the optimum
Okay we’ve managed to hold off until now but we have to now ask – what is Dunbar’s number and why is it so important?
“Dunbar’s Number is the limit on the number of meaningful relationships you can have at any one time. I originally predicted this off the back of a statistical relationship between social group size and neocortex volume in primates – the social brain theory. The equation for this relationship predicts a value of about 150 for humans, given the size of our neocortex. The average size of personal social networks and/or natural human community sizes (for example, in hunter-gatherer societies) from 25 different samples (many based on more than 10,000 individuals) is 154. The largest of these, based on the number of friends listed on 61 million Facebook pages (so it obviously must be true!), gave a value of 149.”
“Corroboratory evidence has come from neuroimaging. There now are more than 20 imaging studies showing that, at the individual level, the size of your personal social networks (however measured) correlates with the size of your theory of mind neural network (essentially the default mode neural network and the grey matter units it connects). There have been three studies of monkeys showing the same effect at the individual level.”
“What has turned out to be even more interesting is the fact that Dunbar’s Number is really a series of numbers, organised in a very distinct fractal series. This miniature social world within which we each live is actually structured into a series of concentric circles round us that have very specific sizes (each circle is three times the size of the circle immediately inside it), involve very specific frequencies of interaction at each layer (we see the same frequencies in face-to-face contacts, phone calling and even social media) and very distinct patterns of emotional closeness, and serve very different functions for us. The layers are at 1.5 (intimates), 5 (close friends), 15 (best friends), 50 (good friends) and 150 (just friends!), extending beyond this to layers at 500 (acquaintances), 1500 (people whose faces we can put names to) and 5000 (faces we recognise). After that everyone is a stranger. This distinctive layering with exactly the same numbers occurs in the distribution of primate species’ group sizes and in the internal structure of groups in those species like baboons and chimpanzees that live in large social groups. In effect, as primates evolved ever larger social groups, what they did was add layers not individuals. We now know that these numbers are optima for the efficient flow of information round a network. The numbers are not an accident. They actually apply to all species.”
The layers are at 1.5 (intimates), 5 (close friends), 15 (best friends), 50 (good friends) and 150 (just friends!), extending beyond this to layers at 500 (acquaintances), 1500 (people whose faces we can put names to) and 5000 (faces we recognise). After that everyone is a stranger.
So being socially connected appears to be really good for your mental and physical health. What are the key areas from your own research that support this? And what about cause and effect, e.g. may some of the effect be accounted for by the fact that healthier people are more likely to be better socially connected in the first place?
“I’ve been involved in one very largescale prospective epidemiological study of the symptoms of depression, based on multiwave surveys across 13 European countries (we showed that having five close friends or three volunteering activities minimised the risk of depression). We have also run a number of smaller scale experimental and survey studies where we have asked people to rate their general psychological wellbeing (how happy do you feel today, how depressed were you yesterday, how engaged are you with your local community, how much do you trust the people round you) and in some cases their physical health as well in relation to their religious attendance, their use of slow-pace community-type pubs (as opposed to high street drinking dens!), and the frequency with which they ate their meals with other people. In one case, we ran a special two-term series of weekly community singing “classes” courtesy of the WEA charity (Workers Education Association, who run adult evening and hobby classes throughout the UK). We compared these with a parallel control group of hobby classes (e.g. card making). Singing is infinitely better, prompting us to refer to singing as the “icebreaker effect”: an hour of community singing builds bonds that make you think you’ve known each other since primary school.”
Singing is infinitely better, prompting us to refer to singing as the “icebreaker effect”: an hour of community singing builds bonds that make you think you’ve known each other since primary school.”
What do you think about ‘parasocial’ relationships and social media in relation to close circles of friends and Dunbar’s number? Is there something about social media in this respect that is novel and more harmful than previous media?
“Everything we have done suggests that people prefer face-to-face contacts over all other forms of digital media (from the skype/zoom and the telephone to email, texting and social media). Video embedded media do better than other forms, but nothing is quite as good as face-to-face. My view is that social media are very good as a sticking plaster if you cannot walk round and knock on someone’s door: they slow down the natural rate of decay in relationship quality that inevitably results from not seeing someone as often as you used to, but nothing will prevent the friendship eventually turning into an acquaintanceship in the 500 layer except a face-to-face meeting. In a very large scale study of a national phone calling database (six billion phone calls over the course of a year by six million subscribers), we showed that if a subscriber failed to call one of their friends for some reason, the next call they made would be 50% longer than usual – as though they were trying to paper over the cracks that had started to open up in the relationship.”
On the flip side, what do you think about the benefits of computers, the internet and smart phones for allowing social relationships to flourish?
“The internet is always a default place to meet new people. And if you are housebound or very shy, it has obvious advantages. In effect, the internet has come to replace the village matchmaker and the village green where people used to meet. The downside is that, ultimately, meaningful relationships only come through meeting in the flesh. This is because when we first identify a potential friend or romantic partner (the process of relationship building is identical) what we first fall in love with is an avatar in our own mind. That’s because we need something to make us get off the fence and initiate an interaction, otherwise nothing will ever happen. In effect, we fall in love with a glossy mental image we have created. In the normal course of the face-to-face world, the shiny edges would be rubbed off this avatar by regular doses of groundtruthing, and we would gradually adapt our avatar to compromise with reality. On the internet, this doesn’t happen. This is why we fall prey to romantic scams: scammers never show themselves, but allow you to become more and more besotted with the avatar you’ve built up until the avatar replaces reality, and no amount of reality check will convince you that the other person really isn’t the ideal of perfection. It’s de Clerambault’s syndrome in everyday life, and is widely seen in phenomena like “guru worship” (proxemic desire).”
You have also written on alcohol and social bonding - what do you think about the recent trend in the youth to drinking less alcohol?
“The three great apes (gorillas, chimpanzees and humans) share a unique set of enzymes that allow them to detoxify alcohols and convert them back into useable sugars for energy – an adaptation that allowed apes (but not monkeys) to exploit rotting fruits on the forest floor at a time, around 10 million years ago, when the great apes were in near-terminal decline in the face of competition from monkeys. It turns out that alcohol is an extremely good trigger of the endorphin system, the principal mechanism that underpins social bonding in primates.”
“Monkeys and apes, and even we humans, normally trigger the endorphin system through social grooming (adapted for our more hairless bodies in the form of stroking, patting, cuddling etc). The sweeping motion of the hand across skin stimulates a very unusual set of afferent C-tactile nerve receptors that are densely distributed throughout the hairy skin. These respond only to light, slow stroking at around 3 cm/sec, target the insula (where they trigger an endorphin response) rather than the somatosensory cortex, and, unlike most other peripheral nerves, have no return motor loop. Endorphin up-regulation creates an opioid high that reduces our inhibitions and makes us feel very bonded (a very strong sense of being immersed in the other person, similar to that experienced in trance states).”
“The problem is that the intimacy of grooming limits the size of group we can bond to a decently primate-sized 50. To bond our larger communities of 150, humans had to find ways of triggering this system virtually without physical contact, allowing us to bond with several people simultaneously in a way monkeys and apes cannot generally do. This involves what I call our social tool kit: laughing, singing, dancing, feasting, storytelling, the rituals of religion – and the social consumption of alcohol and other psychotropic drugs. We have shown that these all trigger the endorphin system, and all create a sense of bondedness to those with whom you do the activity. Most of these can, in the extreme, become addictive, and have adverse health consequences.”
“So, we might feel encouraged by the younger generation’s reduced use of alcohol. But there are two questions we should ask first. One is: are they resorting to alternatives? It has been suggested that they have been switching from a drug we tax (whose consumption we can therefore measure easily) to ones we don’t tax (and hence cannot measure). Some of these may be more detrimental or more addictive than those like alcohol that the human body is adapted to.”
This involves what I call our social tool kit: laughing, singing, dancing, feasting, storytelling, the rituals of religion – and the social consumption of alcohol and other psychotropic drugs. We have shown that these all trigger the endorphin system, and all create a sense of bondedness to those with whom you do the activity.
“Second, the real question of concern should be whether they are turning away from social engagement with real people as a result. If they are ending up in their bedrooms online rather than meeting people, or when they do meet people simply to crashing out on some narcotic, then the consequences will be much worse. And for two reasons. One is obviously the hidden impact on their long term health of drug use. The other is that taking a sledgehammer to get the heady psychotropic effects associated with social engagement may completely bypass the real social bonding benefits they are meant to produce. It has become clear that learning the skills needed to navigate the primate and human adult social world takes a very long time (around the first 25 years of life in humans) and requires a lot of direct experience in the sandpit of life. No two social situations are ever the same, and, as smart as we are at learning, it takes a lot of exposure to different experiences to build up sufficient competence to manage everything the adult social world can throw at us.”
We have focused on clinical topics for much of our Substack to date. One of the many reasons we are attracted to your work is because you have gone beyond evolutionary psychology and extended your ideas to ‘normal’ life and social activities such as singing, music and religious practices.
Do you think there is enough awareness of evolutionary principles among the general public? How would you like to see evolutionary principles promoted? What are the main barriers?
“From an evolutionary point of view, we don’t need to know the detailed explanation as to why something is good for us, so long as we do the right thing and get the benefit. As I sometimes say, it’s much better to put the handbook down, switch off your conscious brain and let nature take over – after all, we have spent several million years honing it effectiveness. Still, having an evolutionary explanation might both entertain us (we are a very curious species and enjoy having our minds stimulated) and persuade us to make the effort to do what is good for us (we are usually better at self-discipline if we know the reason for doing something). Many of our social skills rely on self-control (inhibition), and this requires a great deal of training to master. We are too easily seduced by cheap-and-cheerful ways of getting pleasure, and frequently get derailed.”
From an evolutionary point of view, we don’t need to know the detailed explanation as to why something is good for us, so long as we do the right thing and get the benefit. As I sometimes say, it’s much better to put the handbook down, switch off your conscious brain and let nature take over – after all, we have spent several million years honing it effectiveness.
Finally, considering your multiple roles and incredible output levels, we would really like to know what a typical week is like for you at the moment, in terms of your time spent teaching, researching, writing, etc.?
“I have been retired for some time, so my entire life is now devoted to writing. Earlier, of course, I was as immersed in teaching and administration as anyone else. That said, I confess to have been very lucky with time off for good behaviour – a series of postdocs and research fellowships in the early stages of my career (which meant I didn’t start lecturing until I was nearly 40) and several research-only chairs at the other end (with just masters courses to teach). But perhaps more important than anything else, I was fortunate in the latter half of my academic life to have a large group of very good PhD students, a large number of very hardworking postdocs and research fellows, and many collaborators from a very wide range of disciplines who, between them, did most of the work that gave rise to the story I can now tell. Meanwhile, I am still very busy producing around 20 papers a year, as well as a book every other year.”
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I’d really like him to respond to this (to my mind, very convincing) argument by Maurice Bloch against his take on religion: https://royalsocietypublishing.org/doi/10.1098/rstb.2008.0007. Anyone knows if he’s ever done so?