Robin Dunbar vs. Pop Dunbar

This post is part of a Webinar, Debating Dunbar's Number.

Part 1Part 2 — Part 3

While reading the stimulating critique of Robin Dunbar's social brain hypothesis recently published by Jan de Ruiter and his colleagues, my first reaction was: "Straw man!". On second thoughts, it wasn't fair. The author that Jan de Ruiter and his colleagues criticize is sometimes a caricature of Robin Dunbar. Yet he resembles another important author — let us call him Pop Dunbar. Pop Dunbar stands for many things that have been said in Dunbar's name by the popular press. Robin Dunbar has often distanced himself from Pop Dunbar's ideas, but many of us got interested in his ideas through the Pop version. Pop Dunbar’s ideas are not trivially wrong, and, as Jan de Ruiter and colleagues note, his influence is enormous. For some people, Pop Dunbar holds the truth on what friendship should be.

So, in this post, I thought I would follow in the wake of Jan de Ruiter and colleagues, and explain what I find wrong with some ideas that I attribute to Pop Dunbar. While writing this text I realized that I often (though not always) seemed to find the real Dunbar on my side.

Pop Dunbar's theory says that, in primates, brain size forbids any individual from having more than a certain amount of friends. Because of this limit, primate societies, including ours, cannot go beyond a certain size. This pop theory is simple, powerful, fascinating — and probably inaccurate.



1. The size of primate societies (humans in particular) is not constrained by the size of the groups of friends they contain.



Social life on a large scale is possible without much friendship. Not a picnic, perhaps, but possible. Fear of predation often pushes herding animals together, with very little bonding taking place. Human societies, too, can make do with little bonding: capitalist welfare states make it possible for a big minority to live utterly without friends. Loneliness (defined as having no one to discuss things that matter with) is steadily rising, affecting an important minority of the population in most industrialized countries. We have solitary crowds, "bowling alone", otakus, and Facebook love affairs.

Yet it would be weird — wrong, perhaps — to say that our societies are "smaller" as a result. Being without friends and relying on a corporation or a state for one's living requires more social complexity, bigger cities, powerful states and corporations. Bigger societies do not necessarily mean bigger friendship networks. As Robin Dunbar notes, this is also true of other primate societies. After a certain threshold, grooming cliques may get smaller as groups get bigger overall.

So it would seem that every sensible person, including Robin Dunbar, agrees: there is no necessary link between the size of friendship groups and that of large human societies; at least, such a link exists only up to a point, and most human societies today have moved well beyond that point.

2. There is no strict, fixed and known upper limit on the amount of friends that a primate can make.

Of course, one can only have so many friends; yet that "so many" is not the same for everyone in a given species, and some people go well beyond the mean. The average number of friends per individual is just that, an average – not a limit or a ceiling. There can be much variation, and many outliers. So much so that speaking of "outliers" may be misleading. The variation may be distributed in a non-normal way, with many people having no one to talk to, and a few people having impressive clout. How popular can those exceptional individuals become? We really do not know, but people with much more than 150 friends certainly exist (more on them later).

3. Brain size is not the most important constraint on the size of friendship groups.

Dunbar has argued that brain size puts a tight limit on the size of our circle of friends (see my fifth point). Yet he knows that this limit is not the most important one, far from it. There are more pressing constraints. Many people may never reach the limit allowed by the size of their brain, simply for lack of time.

Humans, Robin Dunbar argues, cannot spend more than 20% of their waking time on face-to- face interactions (this, he claims, applies to the great majority of societies). Making friends is an affective process, one that should be accompanied by changes in our endorphin systems. Dunbar acknowledges three (sometimes more) ways of obtaining somebody's affection: grooming (in non human primates), gossip, laughter, and (maybe) music and rituals. You can only groom one person at the same time, and (the theory goes) you can only exchange gossip and laughter with four or five people at the same time.

In Dunbar's most recent writing on friendship, great emphasis is laid on time and bonding; brain size has all but disappeared from the theory. At the same time, Pop Dunbar’s brainpower— friendship—group size nexus is invading the media.

4. We can establish and maintain bonds with many people.

Close, face-to-face conversation is not the only way we can bond with other people. We have gift-giving. Dancing. Praying. Demonstrating. Mass weddings. Mass huggings. Crowd-bathing. And so on. Those forms of bonding consume much less time per target than grooming or face- to-face conversation. They allow us to reach many more people (albeit in a less powerful way) during the 20 % of our waking time that we devote to social interaction (according to Robin Dunbar).

This twenty per cent average is dubious anyway, since it neglects potential "outliers": hyper-socials, professional communicators, lawyers, therapists, con men, prostitutes, comedians, priests, socialites of all stratas of society… All those who trade in persuasion, contact and networking for the best part of their waking time. Not only can those specialists of social ties build impressive networks for themselves, they build networks for others too. They are go-betweens. A few people devoting most of their waking time to building friendships coalition could make a big difference to the shape and size of our social worlds.

Robin Dunbar occasionally rejoins that those way of bonding have two fatal flaws. First, they are simply too weak: they do not bond us well enough. Second, they often fail to create reciprocal relations. As a result they do not make "true" friends.

I find these objections unconvincing.

First, why should reciprocity be so important? Major social coalitions are sustained, in part, by unilateral interactions. Ask campaigning politicians as they rush from one rally to another. Ask Mata Amritanandamayi, a.k.a. Mother Amma the "Hugging Saint" who hugs thousands and thousands of followers in stadiums. Ask the pope. There can be intensity in unilateral bonding, and those links can be put to use for political or social purposes. Why dismiss them?

Second, weaker forms of bonding can make up for in quantity what they lack in quality. A politician shaking hands may not be bonding with his audience as efficiently as he would be with a long conversation. Granted. Yet just think of the number of hands he can shake! Why should shallow forms of bonding, applied frequently to many people, be less efficient than one conversation every five years?

Yet this kind of unilateral interactions, one may reply, fail to build "true" coalitions of friends. But wait a minute! Aren't churches “true” social coalitions? With reciprocated feelings of attachment (yes, even between strangers), mutual exchange of favors, and a common history of life together? What about cults? Political parties? Supporters of a football team? Why dismiss them?

5. The size of our brain directly does not directly determine the size of our circle of friends.

Robin Dunbar and his team have shown that there is a correlation between the size of brain areas devoted to social cognition and the size of one’s social network. The correlation seems to hold independently of memorization capacities. One could be tempted to conclude that the number of one’s friends is directly determined by the size of one's brain, at least as far as social cognition areas are concerned.

Do we have to accept this conclusion? No.

Taxi drivers have a larger hippocampus (a brain area linked to orientation navigation through space). Is it because people with a large hippocampus are more likely to become taxi drivers? Or is it because taxi driver just develop a bigger hippocampus, for the same reason that ballerinas get strong toes — because of practice? No amount of correlational data can settle such matters. It is quite likely that people who interact with lots of friends get more training in social cognition, and their corresponding areas grow as result. The causality probably runs both ways. In any case, there is no reason to think that small brain areas condemn you to a small social network. Most likely they’re a result as much as a cause.

Indeed, when you think about it, it’s hard to see why brainpower should be such a powerful constraint on social life. We do not have so many problems learning social networks. The average reader of this site can probably remember dozens of novels, scores of movies, tons of historical and political characters great and small — all this in addition to their friends, neighbors, family, coworkers, pets, gods and saints, imaginary friends, etc. You know why Obama hired Hillary Clinton although he disliked her. You may know how Harry Potter felt about Ron’s relationship with Hermione. You could predict with reasonable accuracy what may or may not happen in the next episode of your favorite TV series. Hundreds, thousands of characters, relations, thoughts and reputations are in your head right now, not just to be remembered, but also to be predicted, imagined, toyed with.

Of course, our brains must fail sometimes; but then (as de Ruiter et al. note), we don’t have to rely on our brain for everything. Cognition is distributed. We have computers, books, journals and photo albums. More importantly, we have other people.

An anecdote comes to mind. As he was running for MP in the rural district of Corrèze, François Hollande (now French president) had his staff prepare notes on every person that mattered in his constituency. Once, after a rally, Hollande came across a supporter, Suzanne. The note in the MP’s pocket only mentioned the woman’s name and that of a relative.

Hollande: Suzanne, what a pleasure! How’s life? How’s our dear old Martin?

Suzanne: François… Martin’s dead. (silence) He died last year. I thought you knew. You sent me a letter, back then.

Hollande (after two short seconds of awkward silence): I know, Suzanne, I know. As you can see, I just cannot get used to it.

A good staff and a knack for improvising go a long way. Some may reply that we are not dealing with “true” bonding, or with a “true” coalition here. Or they may dismiss the MP as an “outlier”. I suspect the man who became the French president after so many handshakes would beg to differ.

* * * *

At the risk of sounding optimistic, I think we can all agree that there are very big societies where groups of friends are small; that there is no strict upper limit to the number of friends we can have; that the size of our brains is not the most important constraint on the number of our friends, and does not determine it; that some people can maintain strong ties with thousands of people. While those claims may look like an argument against Robin Dunbar’s hypothesis, I find them coherent with many things he wrote — and above all, obvious.


  • comment-avatar
    Denis Tatone 6 June 2012 (16:18)

    Interesting arguments here!

    I have just one comment about your fourth point. You argue contra Dunbar that, after all, neither reciprocity nor time-consuming interactions are so important after all for the development of social bonds. Well, yes and no.

    I fully agree with you about reconsidering the importance of unilateral interactions and coalitions in human social life. No doubts there can be intense bonding without reciprocity or even long-term interactions, as any person spiritedly teaming up with the supporters of her political party, sport team or cult of choice shows.

    However, not all social bonds are created equal. If we do not define what kind of bonds we are referring to, it becomes difficult to tell whether we can develop and sustain only a certain number of them or more. Is the relationship between two old friends and two supporter of the same soccer team similar? Do they have similar obligations between each others? If so, do they hold these expectations of amitié oblige in the same range of situations or for the same time span? I don’t think so.

    My claim here is simply that we label different relationships as social bonds but they may differ in the benefits they produce, the costs they entail, and the computations they require to be developed. Hence, we may well be able to navigate a social world composed of hundreds of people we feel bonded to only because they endorse our political ideas but we may find maneageable only to develop fewer thick interactions (I’m borrowing this term from Messick) with our fellows.

    For the record, the thick interactions I’m referring to do not necessarily hinge on reciprocity. For instance, deScioli & Kurzban (2009) suggest that we do not ground our decisions to choose or keep friends on exchange calculations (on the contrary, people can become very vocal in denying that friendship is about Tit for Tat), but on the subjective representation of our position in others’ ranking systems, so that we may become friend with these individuals that are more likely to become our allies. This is a good example of a relationship which may grow deep without the need of a strictly balanced trade of favors.

  • comment-avatar
    Olivier Morin 6 June 2012 (18:57)

    Well, I see no disagreement here. I was merely arguing that, as you said, “there can be intense bonding without reciprocity or even long-term interactions”. Of course, as you point out, reciprocity matters a lot in many contexts.

    I also agree when you note that all this loose talk of “social bonds” is dreadfully vague and abstract. It’s like telling the gorilla who guards the entrance of the night club, “Hey, I’m acquainted with X who’s inside.” ‘Acquaintance” cuts no ice. Same for ‘friendship’. In a way, that is the whole point of my post: if you’re like me, you see little point in a general theory of acquaintanceship and friendship — especially if that general theory deliberately ignores asymetric bonds.

    About your last point: yes, deScioli and Kurzban’s point seems to make a lot of sense. More generally, past interactions should not be the only criterion for maintaining a relation. Good deeds in the past, after all, may create unconfortable obligations; we also see in others the opportunities for future alliances. As someone said, bad deeds are easier to forgive than favors…

  • comment-avatar
    Davie Yoon 7 June 2012 (00:58)

    Thanks Olivier for some of the best discussion of Dunbar I’ve ever read. I think a lot of times we run into the idea as first written, and the idea of that idea, which can be influential in its way, although distinct from the original form. This happens a lot in the literature on empathy, theory of mind, etc. I found your idea of casting a Dunbar avatar as a way of dealing with this type of situation so creative and memorable.

    To add a small part to your discussion in point 5: I think as more research is done we can hone in on a richer causal understanding of how brain anatomy and behavior are related. In the social domain (amygdala, etc) the field hasn’t been producing these studies yet (hopefully soon!), but see what’s been done in other domains in neuroscience. For example, there are a couple newer papers from the taxi driver research group that I find very fascinating, but do not seem widely known yet, so I share them here:

    Woollett & Maguire 2011, Current Biology: a longitudinal study looking at the anatomy of individuals before and after they finished the four year intensive training program (“The Knowledge”)
    Maguire et al, 2006, Brain: case study of an expert taxi driver after bilateral hippocampal lesions — unsurprisingly he is impaired, but perhaps surprisingly (depending on your theory), he is not as impaired as you would think

  • comment-avatar
    Gavin Weston 8 June 2012 (18:57)

    Thanks Olivier for defending our paper – I particularly love the differentiation between Robin Dunbar and Pop Dunbar. This is a differentiation which clarifies some of the points we were making.

    We are, in the largest part, not criticising ‘the number’ in and of itself – but the normative applications of the number. Yes, there may be elements of the correlation between neocortex size and human capacity for social relations which we quibble over, but largely speaking our objection is to the increasingly normative application of the number. If it does impose a limit then this limit will occur whether we try to move beyond it or not. If we do have an ability to go beyond this ceiling – and if going beyond this ceiling gives us more social capital or other advantages – what benefit would be served by intentionally limiting the breadth of our social relations?

    Robin Dunbar argues that there is a limit to such relationships of 150. Pop Dunbar argues that something ought to be done to assist people in keeping groups at this size for our own good. Modernity is characterised by immense variability in the qualities of relationships we have – as Denis Tatone commented, “not all social bonds are created equal” – the ‘thickness’ and ‘thinness’ of relationships (again thanks to Denis) should be central to the normative application of the number. Yet these variable qualities of relationship are generally ignored by Pop Dunbar. Pop Dunbar variously applies Dunbar’s number to friendships and workplaces as well as the tightly bonded cliques such as Neolithic villages and hunter-gatherer communities which were the basis for the number in the first place.

    Following the ideological or normative stances of authors such as Mead, Chagnon or Castaneda in the 1960’s social and cultural anthropology became quite sceptical of any anthropologist saying how anything OUGHT to be. This scepticism has perhaps diminished recently as social anthropologists have embraced more applied fields such as medicine or development (or even through the increasingly prominent critiques of capitalism by David Graeber among others) but much healthy scepticism remains – so when Pop Dunbar tells us to limit office sizes to 150 or that Facebook friends above and beyond the ceiling aren’t friends but “voyeurs” we feel forced to question such assertions. There is a massive jump here between the scientific evidence and its possible applications. The applications are being discussed by Pop Dunbar as if they are scientific facts – but the optimum size of offices, the depth relative to breadth of friendships on social networking sites are all testable in their own rights. Pop Dunbar cares not for such distinctions.

  • comment-avatar
    Olivier Morin 11 June 2012 (10:29)

    @Gavin: Very interesting comment. I wonder, though, whether you should take this (rather easy) way out: “Yes, Robin Dunbar is right but the theory is not ripe enough to be implemented by states and firms. Let’s not go normative just yet.” Are you not retreating too quickly from your main point?. Are you sure that normativity is the most important problem that your paper raised? I would tend to side with Stephen Lyon’s comment and reply that it is not.

    Why? Well, first because I have no problem at all with normative conclusions as such. Countless philosophers have tried to drill it into my head that “You Cannot Derive an Ought from an Is (ever, ever)”. I never got that point. If cigarettes cause cancer and are addictive, it’s a good reason to stop smoking. If, as Graeber argues, many debts must not be repaid, this has important policy consequences. If Margaret Mead had been right about education, we should have followed her advice.

    (Yes, should! If a social scientist is convinced he has found an idea that can help people, telling them about it is the right thing to do. Irrelevance is not among our professional duties. I know, he might be wrong, he could do harm — one always could, often does. Yet if he knows the alternative to be worse, he should act.)

    Likewise, if (Pop) Dunbar is right and social life gets cold, unpleasant and nasty (if not downright impossible) whenever humans interact with more than 150 others, then by all means we should downsize our social structures whenever we can afford it. Of course we should. Why not?

    So I suspect that normativity isn’t really your problem; that you think you found important flaws in “Dunbar’s Number”, and you recoil from the normative conclusions because of those scientific doubts. Am I wrong?

  • comment-avatar
    Gavin Weston 13 June 2012 (13:14)

    @Olivier. Any climb-down was entirely accidental – what I had intended to highlight was the value of your distinction between Pop Dunbar and Robin Dunbar. I perhaps went too far in stating the normativity point to be our main one. Our starting point of scepticism regarding the number itself contributes to this position – as you note, with solid evidence verifiable facts should contribute to decision making. But my reticence to declare this to be one of these occasions is not derived from the idea that “Yes, Robin Dunbar is right but the theory is not ripe enough to be implemented by states and firms. Let’s not go normative just yet” – but is based on an initial scepticism that there is enough uniformity in form and content of relationships spanning Facebook friends, Neolithic villages, people on your Christmas card list, colleagues, military units or other social groupings for them to all be thought of as tightly bonded cliques of the same type. Friendship on Facebook has enormous plasticity and often changes in substance specifically through the process of interaction– getting bored of close friends and hiding their status updates or finding a more cursory acquaintance worthy of greater online attention. The plasticity of relationships in modernity or among culture-wielding populations more generally means that even if 150 is a ceiling (and as Steve noted – Read points to another figure and I understand Bob Layton has a forthcoming paper in which he also finds yet another figure for hunter-gatherer populations) the consequence is not necessarily one of social instability – but one of changing substance of relationships. Put 500 people in an office and they won’t fight – they’ll just not all be close friends.

    So in response to your question – in a very roundabout way – it is the grey areas in Dunbar’s number that lead to the scepticism with the normativity. The number may be bigger or smaller. The number may only correlate with a very specific type of relationship. The number may be made superfluous by social and technological buffering of our biological capacities. If one (or all) of these is true – then the normative applications of the number become potentially detrimental.