[Transcript] Episode 93: Robin Dunbar - Why Do Humans Have Friends?

(From YouTube episode)

Dan Riley [00:01:18]:
Robin Dunbar, it is wonderful to meet you, man. Thank you so much for coming on the show. Welcome. I can't wait to have the conversation.

Robin Dunbar [00:01:26]:
Thank you very much for inviting me. Good to be here.

Dan Riley [00:01:29]:
Likewise. I would love to start in getting a little bit of the background story of what got you into evolutionary psychology in the first place. I read on your Wikipedia page this morning that you said once, it was only at the age of about 40, that you had your first real job. And with the meandering mind and curiosity that you obviously have, I wanted to learn what it was about evolutionary psychology that really gravitated, made you gravitate towards it, or interested you in general.

Robin Dunbar [00:02:03]:
I'd like to know who writes my Wikipedia book one of these days. I actually must read it. I have been known to say this, that my first job was that proper job was at the age of 40. That's to say that my first proper job, according to my father, because that meant a permanent job with a pension. Prior to that, I just had a long string of postdoc and research fellowships, which were short term, and you bounced along from one unemployment period to the next unemployment period, these brief periods of paid employment in between. Anyway, so this is a very long and winding road, really. I suppose it came about because of where I did my PhD and the PhD group that I was part of, which was really one of the big, what were then called socioecology groups in Britain, probably one of the leading groups anywhere. So I was introduced as a psychologist.

Robin Dunbar [00:03:21]:
I was probably the only psychologist in the entire group. All the rest were zoologists. I was introduced to zoological and biological and evolutionary ideas, which I sort of married up with my psychologist's interest. And so we sort of trundled along for a very long time. I have to remember, this is the period when sociobiology, the book and the selfish gene burst upon the scene and shook everybody up and turned them head over heels and reconstituted them, or reconstituted their minds in a different way. So it was a very exciting time to be involved. But I worked on monkeys in Africa. I didn't work on humans at all.

Robin Dunbar [00:04:13]:
Monkeys and antelope actually gets worse. We're going downhill, if you like, and probably we're talking about the early 70s here. So from the early seventy s right the way through till the early ninety s, I really worked on animal behavior, animal ecology, evolutionary ecology on animals in the wild. And it wasn't until I got my first proper permanent job at the age of 40 that I hit a period where there was absolutely no money for this kind of field work of about two people who were getting any of it. And if they applied for a grant, nobody else got one. That was it. This was looking pretty bleak. So I just decided to do the kinds of things we did with animals observationally on humans in the street, because we can ask the same kind of questions.

Robin Dunbar [00:05:12]:
And that sort of started to get me interested in humans. And this was sort of really about the time that evolutionary psychology stroke, evolutionary anthropology, was seriously beginning to take off. So I kind of picked that particular ball up and ran with it at the same time because it was sort of a useful guideline to working on humans. So, yes, my career, entire 50 year research career, has been divided into 225 year periods, one working exclusively on animals and the other working mainly on humans. Not entirely all the time on humans, but mainly.

Dan Riley [00:05:55]:
You called that time a very exciting time. And I have to imagine some of the ideas that you were beginning to get exposed to in what sounds like the early seventy s or so must have excited you as well. What was exciting about that framework, that theory? What about it resonated with you and made you excited to spend so much of your life devoted to it?

Robin Dunbar [00:06:19]:
It was really just a rethinking of how evolutionary arguments should be structured as much as anything. So this was, if you like, the selfish gene approach, that prior to that, been a long period of interest, particularly in the context of primate field studies going back into the 50s, if not before, of being interested in why different species had different kinds of social systems and different kinds of social arrangements. And I suppose this sort of partly came out of the anthropology world a little bit, because obviously the anthropologists for a previous century had been studying tribes all over the world and had been asking questions about why different tribes should have different ways of doing things, different cultures, different social systems. And there'd been a move in the 1950s, in fact, in the department that I joined for my first proper job in 1988, that's to say the anthropology department at University College London, by Darryl Ford, the great american cultural anthropologist, who had had the idea of looking at different human societies in the context of their ecologists. Could we explain differences between different cultural groups, different tribal societies, as a function of their ecology? So there's a lot of interest in that spinning around, and the kind of people studying birds and mammals in general started to do the same kind of thing. So I guess where I did my phd in Bristol was one of the leading places interested in applying these ideas to both birds and mammals, and particularly to primates, which is sort of why I ended up there. So this was a very kind of formative period building on this background, right? And then along comes the so called selfish gene revolution, which says, actually, we need to get the evolutionary processes of the argument right here. The way evolutionary processes work is for the benefit, if you like, of genes rather than the benefit of groups.

Robin Dunbar [00:08:42]:
And so this was a very kind of exciting time because everybody just went, oh, yeah, you're right, that's what we should have been doing all along. And an awful lot of very exciting stuff came out of that. Wd Hamilton, Bill Hamilton coming up with his concept of inclusive fitness as an explanation for the evolution of, well, sociality in bees, essentially, was what he'd been working, you know, other people. The beginnings of sort of what was then called behavioral ecology, I suppose, still is optimal foraging theory, applying a lot of ideas from economics or the mathematics of economics to animal behavior. So this is quite a period of foment, really. It wasn't a sort of massive, violent revolution, as some might portray it. There were some skirmishes with people in the social sciences mainly in the periphery somewhere, but most of us weren't troubled by that kind of thing, but it was just a sort of natural shift. Everybody just went, oh, yeah, gosh, we just need to reset the gears here a bit.

Robin Dunbar [00:10:00]:
And away we went. And that did kind of open up a completely new perspective. In fact, once people started to think in terms of what individuals were doing within a social system rather than what the emergent properties of the social system were like.

Dan Riley [00:10:16]:
You mentioned the word sociobiology earlier. I had the biographer of E. O. Wilson on the show about a year ago, and we were talking about the time at Harvard when he released that book. And know, arguably he was one of the first people to be, quote unquote, attempted to be canceled at the time of the publication of that book. And I've had David bus on the show. He was one of the first few guests there. And I'd love to give you an opportunity to talk about.

Dan Riley [00:10:47]:
You talked about the perspective shift just then, or how this was a new framework to think about human beings. And David said when I interviewed him that the application of evolutionary psychology can be given not just to human nature, but to all of the social sciences in general, which he admitted was a bit of a bold claim. I'd love to give you a platform to talk about how you think evolutionary psychology can be properly placed as really the way to attempt to explain human nature in general, as I understand it, through natural selection, evolutionary theory and sexual selection. What has really blown your mind over the years that you've researched the field to maybe rethink yourself and your own nature and people in general?

Robin Dunbar [00:11:43]:
My goodness, that's a very small question. And yes, speaking of. Yes, just to go back a minute to the kind of sociobiological wars they were exclusively confined to, probably Harvard. I was going to say the United States, but I'm not even sure if the whole of the United States was engulfed by it. But certainly we weren't in Europe particularly. Most people just went, well, there was a bit of a kind of grumbling going on from the social sciences about this, which still continues to this day to some extent. But I'm not sure how much E. O.

Robin Dunbar [00:12:36]:
Wilson was actually cancelled, as it were. It wasn't a case of cancelling, it was more a case of pouring a jug of water over his head. That's right, the iconic event that went down in folklore. It was quite funny, really, watching it from over here. And it's weird because everybody, I never actually met him, but everybody who knew him, he was one of the nicest people imagined, but still. And he liked his Beatles, or whatever it was that he was really interested in. Just sort of this throwaway chapter at the end of sociobiology, which was this huge Tome on animal behavior and animal ecology, and just a short chapter at the end saying, well, maybe we could apply some of these ideas within the study of humans as well. But I would go further.

Robin Dunbar [00:13:33]:
It's not just a matter of sort of evolutionary influences in anthropology, where they're fairly deep now. I mean, there's still a rift between the cultural anthropologists, as they would be known in America, and the kind of evolutionary biological anthropologists who take much more of a kind of sociobiological line, if you like. That's still a deep rift, I think, and I'm not sure if they actually ever talk to each other, but the impact potentially, of evolutionary ideas applies everywhere, to every field of the humanities and social sciences and within the life sciences. Within the sciences. I've argued this explicitly. It applies in economics. Maybe we'd get better economics if they understood what really motivated people to do things instead of just trying to chuck lots of money at them. For example, it applies in history and archaeology.

Robin Dunbar [00:14:46]:
They call themselves humanities, but realistically, in the old greek sense of science knowledge, they're proper sciences. They proceed by evidence and test hypotheses. And that's true in literature. If you look at literary criticism, and I've been involved directly in projects looking at the kind of evolutionary psychology of drama, for example, in storytelling, what is it that makes us keep coming back to these tear jerkers like shakespearean tragedies when you might think once is enough? But no, we keep coming back, paying good money to see it over and over again or read the book over and over again. There are people like Lisa Sunshine who are applying some of these ideas directly in terms of evolutionary sort of aspects of cognitive psychology, very much to unpicking the structure of novels and how different authors have constructed their stories, as it will, and tell them so there is no limit to as long as there are humans involved, that's their human minds, then evolutionary ideas must apply. One has to be kind of, I was going to use the word cautious, but that's not the right word. Throw in a caveat, as it were, to just point out for any species that has a big brain, humans, but also all the primates and probably a lot of the other mammals and birds too, they're not genetic automations. They actually do think about what they're doing and choose between alternative strategies.

Robin Dunbar [00:16:39]:
Question is, do their choices of behavior that they make reflect what is the optimal strategy from an evolutionary point of view? Or is it purely cultural? Maybe the answer is no, it's not purely cultural. It's quite obviously and self obviously underpinned by evolutionary mechanisms, as it were.

Dan Riley [00:17:06]:
You must get this a lot at cocktail parties and from acquaintances and friends. And I have to imagine most of the people who are watching this or listening to this will have some understanding of the basics of evolutionary psychology. But for those who don't, how do you, in as simple terms as you can, give an explanation for this framework of what it really means when approaching human nature and approaching people in general?

Robin Dunbar [00:17:35]:
Okay, I guess the simple answer is that evolution drives organisms, or drives the psychology of organisms as well as their anatomy, if you like, towards strategies and solutions that are as best as it can manage to optimize the well number of great grandchildren you produce. That's how evolution works. Now, the issue is, and one has to always to remember this, that things like bacteria, insects and life can probably be characterized as genetically structured automatons. The machinery, and it's very simple, machinery is directly guided by genetic inheritance. But once you start to get a brain, as you do in the sort of mammals and birds and leading up to humans, you start to free off the immediacy of decision making from the background genetic processes involved. So the whole point of having a big brain, like we all do, is to allow you as an individual organism, freedom to assess the costs and benefits of different actions. So the way I'd kind of describe it is what evolution provides you with is the kind of white lines on the football pitch, right, and the rulebook, and it tells you the rules of how to play the game, but it doesn't tell you how to win the game. You have to figure that out, and you figure that out by practice and a lot of experience.

Robin Dunbar [00:19:33]:
And that's because once you get into this kind of game, the social world is so unpredictable that you could never produce an automatum that would function effectively in it. You just cannot write it into the genetics of the organism. What the genes do is gives you the machinery and a bit of guidance along the way. So it's a bit like the white lines on the football pitch, like our predispositions to behave in certain kinds of way. But the real issue in the end is how good you are at making the right choices as you go along in life. And you're free to make a hash of it if you want to make a hash of it. Nothing in evolution to say that you can't do that. It's just that unfortunately, the way genetic evolution works, your genes will not be represented in 1000 years time.

Robin Dunbar [00:20:38]:
But why should you care as an individual? Evolution might worry. Well, no, evolution doesn't worry about anything, does it? But this difference between the strategic elements that underpins the evolutionary process and the tactical elements, which are us individuals trying to work out what's the best way to live our lives and get the most out of it. With this kind of guidance built into the system which says, well, actually, it's all about genetic descendants, as it were. But how you get there can be very complicated. Historically, we've always assumed since Darwin that this is all about producing babies. But in the 1950s, the population ecologists had already worked out that that was only half the story. This lacks principle. It's not about pumping babies out.

Robin Dunbar [00:21:36]:
It's about rearing adults. Or as John Bedard Smith once famously said, evolution is not interested in babies, it's interested in grandchildren. It's just that there is a problem getting you to grandchildren. They're called babies.

Dan Riley [00:21:56]:
I know when we were emailing about having you come on the show, one of the themes that I wanted to go over with you is friends. And you wrote a book on friends, which I've been reading over the last few days, and you just mentioned a lot of evolution is about trying to live, figuring out how to figure out the way to live one's best life. And you go into great lengths in the book about the importance of friends to human beings. And this is another basic and simple question, but why this subject? Why did friends for you come up as a subject that was worthy of what I'm sure was many long hours and probably at least multiple years of your time and research?

Robin Dunbar [00:22:43]:
And I hasten to say a great deal of puzzlement. What on earth are these things called? Friends shock. All right. A discovery of a whole new world out there I didn't know existed. The answer is working on primates, because I think what working on primates inevitably reminds you about is just how important the social group actually is. So the sociobiological, the selfish gene revolution kind of made us throw away all the kind of group level effects and concentrate on what individuals are doing, which was fine. That was a useful antidote to some very bad evolutionary thinking that had gone on prior to that. So it was a very healthy thing to do.

Robin Dunbar [00:23:35]:
But what it did a little bit was throw the bath out with the baby, for very good reasons, I think because we didn't really understand how social groups sort of functioned or how important they were. They were just seen as sort of random collections of bees round a honeypot, I think. But it's become clearer and clearer in the sort of 50 years or so since then. The very social species of mammals and birds, the group itself is part of the individual's evolutionary strategy and plays an extremely important role in allowing them to cope with and overcome the vicissitudes of everyday life in this grim place called earth, just forever throwing badly pitched balls at you when you least expect it, and you have to deal with them. So these are the sort of contextual, serendipitous things that happen and could be sort of floods or famines or heaven for fen, climate warming, or it could be your neighbors raiding you, or predators turning up in large numbers. Any of these things that kind of threaten your ability to survive and reproduce successfully, they're unpredictable. They turn up out of the blue. You have to be able to think on your feet and find a solution.

Robin Dunbar [00:25:10]:
And groups really turn out to be very, very important for primates and in the context of that very long and complicated story, which is what I'm trying to put together in one of the books I'm working on now, so people could see the whole picture. But the essence of it is that in order to create these kind of very deeply bonded, stable social groups, primates and a number of other species of birds and mammals, but nothing much beyond that. A few, I should hasten to say, species of birds and mammals, by no means. All in effect, had to invent friendships, so they had to create these bonded relationships to provide the kind of steel frame that holds these groups together through time. And so this kind of. It's interesting, actually, because all this socioecology stuff from the had never thrown away. It was sitting there on the back burner, I think, and sort of spend a certain amount of time sort of trying to think through it, trying to understand what it was about the nature of these groups, in primates in particular, that was important. But once we started working on humans, I think it really brought it home that there was something that really needed to be explained.

Robin Dunbar [00:26:39]:
I suppose this had a lot to do with the social brain hypothesis that appeared out of the blue in the late 80s. Number of people started talking about, why do privates have such big brains? Well, it must have to do with the fact they live in very large, complicated societies. They need a big computer to manage all the relationships. And I got very interested in that early on. We produced some data to show that it was actually the case, and produced, shed a little more data in the intervening 30 years. And it just became obvious that a great deal of the machinery of primate cognition, as well as a great deal of their time, is devoted to actually trying to create and maintain coherent social groups. But it's done through person to person relationships. So these kind of friendships, if you like, provide the scaffold out of which a stable group emerges as an emergent property.

Robin Dunbar [00:27:50]:
It's kind of byproduct. And then it's turned out that in the last decade and a half, huge quantities of epidemiological evidence has come out of medicine primarily to show that the single best predictor of your psychological health and well being, your physical health and well being, even how long you're going to live into the future, is simply the number and quality of close friendships you have. And then in the last decade, people have been finding exactly the same results in primates, in dolphins, any of these intensely social species. And so this whole area of the emergent properties of groups as part and parcel of the evolutionary strategy that these primate species in particular, and therefore humans, the more so have evolved, seem to be coming more and more important, more and more important to understand how this worked and how it's gone. You know, since then, we've been able to show that the structure of these groups have very, very distinctive properties. It's a kind of layered structure. A fractal series is involved, sometimes known as a Dunbar graph, thanks to a couple of indian mathematicians. And these layers, we just have huge quantities of data for this.

Robin Dunbar [00:29:33]:
I mean, we're talking about data sets, a dozen data sets, each of which is sort of in excess of a million people, showing that these layers exist. The most famous of which is the Dunbar number of 150, which turns out to be just one of a series of layers. These layers turn up in online multiplayer games, in the size of residential caravan parks, trailer parks, at least in Germany. I don't know about the mean Germany. The size of distribution is just an absolute map onto the structure of all modern armies around the world. It appears in history. We find it in all sorts of kind of bizarre contexts, really. And then finally, there they are.

Robin Dunbar [00:30:44]:
The same layers, same numbers, same structure, in primate social groups as well. Orca social groups have them, dolphin social groups have them. So all these intensely social seers, something weird. And we've been able to show now, at least a bunch of american mathematicians that I've been collaborating with, this is way beyond my mathematical competences, been able to show that these numbers are actually optimalities. They're what physicists will call criticalities. They're points at which, essentially, information flow is optimized in network. So each of these numbers represents a kind of optimal point, a peak, if you like, with the big peak at 150. And these other numbers either side of it are kind of like harmonics.

Robin Dunbar [00:31:38]:
This is really very exciting stuff, because we really are seriously getting a social physics together as a discipline. I mean, the physicists who work on social networks have been talking about social physics for a long time, but theirs is a kind of abstract form of behavior on artificial networks. You kind of go, not sure if they're exactly what humans do, but now we have such a deep understanding of what's going on in the nature of our social worlds, the social worlds we live in, and how these then map onto the way the world outside is organized, the structure of organizations, as it were. I think we could realistically speak of social physics here.

Dan Riley [00:32:32]:
Absolutely fascinating. And just to add on to that comment, there's a great graph in your book about friends, which I would encourage anyone to look, which gives an incredible visual about what you're talking about. And it's concentric circles. And I want to read out what is detailed in that graph and then get your comments on it. And these are what are termed in the book, circles of friendship. In the middle of the bullseye is intimates, something called intimates, which is 1.5 people. Close friends is second with five best friends is third with 15 good friends, fourth, 50 friends. Or Dunbar's number, which I'm sure is an annoying reference to you throughout your entire life.

Dan Riley [00:33:22]:
Dunbar's number. But friends being 150 acquaintances, 500. And known names. Known names at 1500. Maybe I'll just stop right there and give you any additional comments because you're famous for really, the friends circle, the 150 number. But I think if I just heard you correctly, the social physics you reference are related to all of these different tiers, the intimates, the close friends, the best friends, et cetera.

Robin Dunbar [00:33:53]:
Yeah. So what you've just described is what has sort of been labeled a Dunbar graph. Right? So this is a fractal structure. It's a hierarchically inclusive structure. So each layer includes all the people in the layer, or layers within it, as it were. So the bigger layers include the smaller layers. So your 15, whatever it was you said, because I can never remember too many names here. Your best friends, as it were.

Dan Riley [00:34:29]:
That's right.

Robin Dunbar [00:34:30]:
Includes your five close friends. And your five close friends includes your one and a half intimates. There's one more layer at the outside, and that's at 5000, which we didn't discover. Okay. So we discovered these layers by looking at the structure of face to face contacts, at frequencies which people called so, telephone databases. The one we particularly looked at was mobile phone provider that had 20% of the entire population of one very large european country. So we're talking about, I think it was 6 million customers and 6 billion phone calls over the course of the year. It's huge, huge numbers.

Robin Dunbar [00:35:19]:
So looking at who's calling who, how often we've looked at the structure of Facebook posts, the structure of Twitter posts, you get exactly the same picture however you do it. And that's what made it remarkable. So we picked up these numbers and then the ones we knew about were 515, 5155. Hundred, 1500. So 1500 is sort of all the people whose faces you would recognize. So whether you like it or not, Donald Trump is in everybody's 1500, right? Because if you saw him walking down the street, you would know who it was absolutely instantly. Of course, he'd look blankly at you and you sort of clapped him on the back and said, donald, come and have a beer. And probably the very large gentleman with a bulging right pocket under his jacket next to him may have some words to say to you, but those sort of people that appear in the news are all part and parcel of that layer that turns out to be the average size of tribes in small scale societies.

Robin Dunbar [00:36:38]:
But some psychophysicists who are interested in recognition of pictures for some obscure reason, attempted to do a study to see at what point people kind of said, well, I've never seen that photograph before and that turned out to be 5000. And when I read this paper, I just went, wow, that's the bit we're missing. And that is the last possible circle because everybody beyond that circle is a complete stranger. So somebody in that circle, you know the face, you don't know who, they can't remember who they are. You may never have known who they are, but you've seen that face before somewhere and that seems to be about 5000. Then the other end of the scale. I used to kind of joke when I was giving talks about this and say, look, this is a highly regular fractal series here. Each layer is three times the size of the layer inside it.

Robin Dunbar [00:37:32]:
If you count backwards or downwards for 150, if you like, there's a layer missing and that has to be at one and a half. And everybody'd go, what do you mean? How can you have one and a half relationships? And I'd go, because it's an average for the population. That means half the population has one and the other half has two. And they'd go. And they'd go, so you're talking about monogamy in women versus polygamy in men. And I'm going, no, it's the other way around. And that is that women have this very characteristic thing called a best friend forever, or a BFF, as it's come to be known, in addition to a romantic partner. So we have quite good evidence.

Robin Dunbar [00:38:25]:
You can really only have one proper romantic partner at a time. It's very costly emotionally, and in time you can have lots of sexual partners that you don't really care about necessarily. But for a deep romantic relationship, it really does seem to be so costly that you only have one. But what women also have is what I suppose would have been called a platonic friend in the olden times. And that's somebody who provides emotional support and advice and help and stuff like that. Men don't. They have a kind of best buddy that they might go have a beer with. They've probably known since they were at first air primary school like that.

Robin Dunbar [00:39:14]:
Right? But if you look at what they say when you ask them, do you have a romantic partner? Yes. No. Do you have a best friend? Yes. No. They will only ever declare one at a time. So they either have one or the other, but not both. Somehow the kind of best friend gets kind of downgraded to the next layer, doesn't disappear altogether, it's downgraded to the next layer. This is what the issue is.

Robin Dunbar [00:39:44]:
It has a lot to do, I think, with the fact that women's relationships are much more dyadic and focused. It matters who you are as an individual, not what you are or what you do. And therefore their relationships are very intense with each other, their friendships, whereas men live in a more club like world, which is much more anonymous. So it doesn't really matter at all who you are as an individual. What matters is, are you in my club now? The club is small. It's only four or five people. The definition can be extremely casual. It's four or five guys that go and have a beer on a Friday night together once in a while.

Robin Dunbar [00:40:30]:
And the definition of club membership, the criterion of club membership is, can you get a glass of beer from the table to your mouth without spilling it? If you can, you're in the club. Or there is the well known club that many husbands belong to, which is the club that consists of the husbands of my wife's girlfriend, which is a group that kind of emerged out of the social arrangements that the women make. And then the guys kind of, after they go along to various social things that the wives get together, and then the wives and girlfriends, as it were, and then sheepishly standing around the corner of the room pretending to sip their glass of wine, they eventually say something to each other and gradually that becomes, well, why don't we go and have a beer together or something like that? Usually there's some activity involved. It might be a group that goes hiking. It might be a group that plays five aside, soccer every Friday evenings or something like that, or mountain climbing or kayaking, or just sitting around having a beer. It's very much an activity based thing, whereas these women's friendships are much more dialectic, much more conversation based. That's what our data show. And so we have a very nice demonstration of this from Facebook profile pictures, which we looked at many thousands of tens of thousands of once, which showed that if there were only two people, we'll throw out sort of me and my mum or me and my baby photographs.

Robin Dunbar [00:42:20]:
So two people the same age, if there's only two in it, it's very likely a female page, and there's a 50 50 chance that the other person is male, presumably the romantic partner. 50 50, it's female. Although some of those might be romantic partners, a good proportion are my best friend forever. So important are those in their lives. If there's four people in the picture, it is never a girl's page, it is always a boys page. And it's four guys and they're sitting on the top of the mountain looking down over Machu Picchu, or they're crowded in a goal mouth, or know, sort of pulling their kayaks together or on the lake or whatever it may be. It's that kind of thing. So this is really big difference in the way, the dynamics, the internal dynamics of how friendships work.

Robin Dunbar [00:43:23]:
And I hasten to say in addition, that these. Okay, so that's why. Long roundabout explanation for why you get the one hop. But I should say that right the way through these layers, it's a 50 50 division between extended family and friends. So for most, out to the 150, that's the absolute limit. There are very rarely family members out beyond 150. In the two layers, five and 15, they're exactly 50 50 family and friends. In the 50 layer, you tend to get more friends and fewer family.

Robin Dunbar [00:44:03]:
And in the 150, you tend to get more extended family. Now your extended family is taking you out to kind of cousins, second cousins. But people who have large extended families in all societies, including ours, some people do. They just happen to come from a lineage which just had sort of ten or twelve kids. Um, then very often. Or what you'll find is they have very few friends. I don't know how many times people have come up and said that to me. I come from a very big family.

Robin Dunbar [00:44:44]:
I've got 41st cousins. This is not entirely that rare. It takes me all my time to get round them, to check up on them and so on. I don't have time to have friends, whereas my spouse comes from a very small family and has no family and lots of friends. It's very confusing for me. So these kind of things pop up constantly, and it never ceases to surprise me how often you hear about these things. Just sort of proof of the pudding, if you like. But what this seems to be pitched out of is the fact that that 150 is the limit for all kinship naming practices all around the world.

Robin Dunbar [00:45:36]:
There are only eight different kinship naming systems. I keep forgetting which English is, I think it's hawaiian or something of skill like that. But there are various other ones, iroquan, so on and so forth. There are only eight of them. They're all pretty much the same, essentially, but they kind of do mirror images of each other in certain places that are in themselves quite interesting. But the essence of them is they only go out to about second cousins. There are no kinship naming systems in the world. There's no society in the world that has a name for anybody further out than that.

Robin Dunbar [00:46:21]:
And it turns out that if you figure out the number of descendants from a sort of great great grandparental pair who married, if you like, and had children, who then had children, who then had children at the rates at which they do in undergatherer type societies where there's fairly high death rates among children, but also no contraception or no formal contraception, so they tend to have large numbers of children, then 150 is very, very close indeed to the number of living descendants in the three living generations for a pair who are the great great grandparents of all the living children generation. Right? And, you know, that's about as far as we need to go in terms of kinship. We don't need to worry about sort of people beyond that. What we do is we kind of stick labels on them in the form of funny haircuts or moustaches or how you have beard or the beading you have on your parker, or whatever it may be, and things like dialect, so we can recognize who belongs to our tribe, for example. So we have lots and lots of those. And this fed back into it all gets very complicated because it's all so interrelated. But once we realized that, we began to appreciate that, in fact, these things we use, cues we use to identify members of our tribe of about 1500 people, are in fact the same mechanisms we use in identifying friendship. So this is what we call the seven pillars of friendship.

Robin Dunbar [00:48:13]:
So the seven dimensions of friendship, all of them cultural, none of them are biological, which kind of identify the community, in a sense, the language community you come from. So they're things like the language you speak, or if you come from a very big language, it still works with us. Even with something like English, which a billion people have as their first language, or whatever it's supposed to be, we worry about. Is that a Greenwich Village accent I hear from New York, or is it a Harlem one? We make these very fine distinctions, and it's these social linguists figured out way back in the think it was, that you could place a native english speaker within Britain to within 25 miles of where they were born the moment they opened their mouth from the words they use, the way they pronounce words, the grammatical structures they have, it's a very, very small scale. And that turns out to be, actually, if you think about it, about the size of the ranging area of a tribe in hunter gatherer societies. So that's one of them. There's things like where you grew up, your hobies and interests, your career trajectory. This is why lawyers have mainly lawyers as friends, once upon a time, unkindly.

Robin Dunbar [00:49:54]:
Clearly, we all thought it was because nobody else would speak to lawyers. But no, it turns out to be true of medical folk. It turns out to be true of academics. It turns out to be true of journalists. It turns out to be true of almost every walk of life. Plumbers, electricians, whatever. You gravitate towards people who kind of work in the do the same kind of job as you because you've got something to talk to them about. You've got common interests, funny stories to tell about cases you've done or rewiring jobs you've had to do, and all these kind of things.

Robin Dunbar [00:50:31]:
Your career, as it were, provides one of those. And then there are things like your worldview, which is a kind of composite of your religious, moral and political views, your hobies and interests, and then the two interesting ones, which are your sense of humor and your musical tastes. And these turn out to be very powerful influences on our choice of friendship. So our friends, even our preferred family members, share more of the seven pillars with us than our less preferred ones. So how many pillars you share with somebody places them in one of those circles, and we've recently shown that. And I think this explains why. What happens when we meet new people. We devote an awful lot of time to them.

Robin Dunbar [00:51:22]:
We keep ringing them up, trying to making arrangements to meet them, what we're doing is checking out where they lie. And then once we've kind of figured out they're a sixer or they're a threer, or maybe they're just a oner, we anchor back to the kind of rate of contact which is appropriate for the circle that they'll then fall in. So we published a paper last year which was based on telephone contacts, cell phone contacts from three different countries, the US, Britain and Italy, and we showed that we could predict effectively which layer of friendship. So for people who were new friends, so this number appears for the first time out of nowhere. They've never called it before. We can predict which layer they will sit in and how long the friendship will last before they stop courting them on the basis of the frequency of calls in the first month, and that appears to be them checking up. Let's go out, let's go out, let's do this, let's do that. And you kind of go, right, think we'll put them, we'll downgrade them to the 150 layer.

Robin Dunbar [00:52:40]:
We only have to see them once in a while.

Dan Riley [00:52:43]:
This, to me, seems like such a massive step forward in our understanding of humans and human social dynamics. And you go into great detail in the book in providing data about how universal these categories seem to be throughout the world, and that this really is applicable, seemingly with some slight variation around the world. And I want to go over again, just for the listeners and the viewers, the categories to have as a framework for circles of friendship. Intimates, 1.5 close friends, five best friends, 15 good friends, 50 friends, 150 acquaintances, 500 known names, 1500. And I know we're getting close to the end of our conversation. And so much of your book, and so much of the reason why I do these interviews is just for my own curiosity, but also to try to help people get great knowledge. You talked earlier about, and you go into this in the book about how powerfully predictive having close friends are for your immune health, your health in general, your sense of well being. And this may be a decent place to close, but you talk about this in the book about how once in a lifetime activities like funerals and deaths, funerals and marriages are typically the 150 range where the friends come.

Dan Riley [00:54:14]:
A weekend barbecue is given as an example for good friends, the 50 range to appear when you think about human flourishing. And I interviewed Mark Scholes about a year ago, who led and co wrote the book about the Harvard Happiness study that was a longitudinal study of 80 years. And the big takeaway from all of that research was the most important thing to a flourishing life is close, connected friendships, relationships. And is it your view that it's really the inner circles, the lack of an intimate, a lack of a close friend, maybe the lack of a best friend. So going from roughly one to 15, that if people don't have that, a lot of people have friends that they see once a year or once every couple of years, it's really the inner circle, in your judgment, that matters so much. Maybe the inner two or three. I don't want to put words in your mouth, but I'd love to give you an opportunity to talk about that.

Robin Dunbar [00:55:14]:
Yeah. All these huge epidemiological studies, like the Harvard one you just mentioned, but many others that are about actual susceptibility to diseases. The one I like is a metaanalysis of, I think it was 148 heart attack studies. You can't argue about the outcome. The trouble with these kind of standard sociological and psychological surveys. Are you happy today? Well, yeah, sure. Am I as happy as I was yesterday? It's not clear. That's fine.

Robin Dunbar [00:55:54]:
We kind of cope with that and the error variance, as they say. But when your measure is how long did you survive after your first heart attack? Did you make it to twelve months? You can't argue with that. You did or you didn't. So I think it suggests a great study. And what they show is exactly what everybody else shows. It's this inner core of five best friends, what we now call the shoulders to cry on friends. For obvious reasons, they seem to provide their kind of support that both gets you out of depression better than any pills and allows you to overcome serious medical diseases better. I mean, these are statistical.

Robin Dunbar [00:56:44]:
Just having friends is not going to help you live forever. I'm afraid you can't legislate for that. But statistically you definitely do better, much better. What's interesting is how that actually works. So it's about, I think, what those close friends do. And usually that group of five, two of them will be family members, two of them will be kind of friends, as it were, your best best friends, and then kind of an OD one to make it up. They do two things to you, they have this obligation and commitment to you that they will turn up with a bowl of chicken soup when you're laid out with some dread disease and kind of do jobs for you of that kind, as I sometimes put it, they are the only ones who, when you go around and bang on their door and say, my world has fallen apart, I need some help, will put the baby down and come and help you. Anybody else will say, actually, I'm just dealing with the baby right now, but I'll come around tomorrow.

Robin Dunbar [00:57:48]:
Tomorrow is too late. But for somebody to be willing to do that, the relationship has to be really deeply structured and built. And that takes time. And we devote 40% of our total social, available social time to those five people. That's about half an hour a week each, something of that. More than that. It's about half an hour a day, isn't it? Those relationships won't work like that unless you invest a lot of time and effort in them. And of course it has to be reciprocal.

Robin Dunbar [00:58:29]:
But it turns out that what makes that work is what you do with them. So these are all our kind of standard social interactions. So it's all the things like laughing and singing and dancing and eating together and telling stories together. All of these trigger the endorphin system in the brain. Just part of the brain's pain management system. And that creates this very intense form of bonding. And also because it's an opioid, not an opiate of the kind that causing so many problems for us, but they're sort of chemically related. But we don't get addicted to endorphins.

Robin Dunbar [00:59:12]:
They give you this same uplift sense of peace. And the cares of the world are dropping off your shoulder, and warmth and coziness. It's not a happy drug. It's just a peace of the world kind of drug, if you like. And that creates a sense of bonding. And so it's an absolutely incredible antidepressant. And you don't have to pay for it. All you have to do is go and spend a bit of time with your friends.

Robin Dunbar [00:59:41]:
So you can see how you get this kind of psychological well being effect. But it turns out that the endorphins, one of the byproducts of the endorphins, the brain pumping out endorphins in any of these situations is to activate the natural killer cells and the white blood cell system, the immune system and the natural killer cells. Target in particular, we think, anyway, viruses generically, and some cancers conceivably other stuff. But those are the two things that have been pointed out. So now you can see a reason why it should have a physical health consequence directly. This is a kind of byproduct. The real kind of evolutionary purpose, if you like, is very much the building of friendship and of course making you happy. And this is the interesting thing about endorphins.

Robin Dunbar [01:00:42]:
Everybody batters on about oxytocin as being the sort of social hormone? The answer is no. It's quite good for some things, but it's not very good for building friendships. It's very good for romantic relationships and relationships with your children and babies, but it's not particularly useful for building friendships because the difference is with oxytocin, you either have the right allele for oxytocin and do lots of it, and you're very kind to everybody then. But endorphins allow you to make other people kind to you. This is rather more important. So by doing all this stuff like laughing together, we trigger endorphin surges in both parties, and it's fun for all of us. And if you can't do that, you're not going to have a friendship, I'm afraid, in some form. I mean, you can do it by telling incredibly tragic stories to each other, although there's probably a limit to which most people are going to sit and listen your tragic stories night and day.

Robin Dunbar [01:01:52]:
But any of these things, like eating together, singing and dancing, laughing, stroking, patting, all the kinds of things we do with our closer friends and family, kick the endorphin system in and make it pleasurable for both parties, which is back to homophyl. Again, we like people who are similar to us ourselves, who like the same kinds of things as us. So you've got this mechanism which underpins social bonding, which goes back to primates. It's. It's derivative of grooming in primates. And, you know, we've exaggerated it and exploited it, as it were, in cultural terms, in ways that trigger the same mechanism. But it turns out that this mechanism is hugely beneficial for our psychological well being as well as our physical well being, has dramatic impacts. So, yes, go out and make a friend, but really, you have to invest a lot of time and effort, which means you have to be rather tolerant of the other person's foibles.

Robin Dunbar [01:03:02]:
Otherwise it's just not going to work in the end. This is why you get homophobia. Extroverts prefer extroverts as friends. Introverts prefer introverts, and you can see why. And same with romantic partners, really, because there you are, 06:00 on Saturday evening, sitting on the sofa at home. What should we do tonight? Two extroverts, they want to go clubbing. Fine. This is Nirvana.

Robin Dunbar [01:03:27]:
Two introverts, they want to sit in with a tv dinner and watch the film. That's another kind of nirvana. But an extrovert and introvert together, one wants to go out, the other one sit in. This is an insoluble problem, because whoever agrees to go with the other one is going to feel miffed. They're not getting what they want to do. They're just having to put up with the other person. So you can see these kind of stresses make all kinds of relationships, whether it's romantic relationships or friendships or even family relationships, difficult. And you can see why we have these very strong preferences for people who are like ourselves.

Dan Riley [01:04:07]:
Yeah, Robin, this stuff is just so damn interesting. And maybe we could do this again. I have so many other subjects and notes I'd love to go over with.

Robin Dunbar [01:04:17]:
You, but we never got past question one.

Dan Riley [01:04:22]:
Sometimes that happens. It's a signal of a good conversation and a brilliant mind. I love the social physics idea, and I think you've made groundbreaking observations about people. And some of these things are just so simple for recommendations. As you said, it's free to do these things. And I think we often forget just how important these sort of investments really are for us, just in general, for living a flourishing life. And so maybe we can talk again at some point in the future. But I so enjoyed this, and I love your, ah, your research and your contributions.

Dan Riley [01:05:03]:
Thank you so much for, for taking the time. I really hope we get to talk at some point again in the future.

Robin Dunbar [01:05:08]:
It's a great pleasure. Thanks for the invitation.

Dan Riley [01:05:11]:
My pleasure. Thank you, sir.