Dunbar's number

Robin Dunbar vs. Pop Dunbar

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

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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.

Are we sure we can groom beyond Dunbar's number?

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

Part 1Part 2Part 3

When I heard about Kanai et al.'s paper [1] announcing a correlation between grey matter density in several brain areas and online social network size, I immediately updated my Facebook status, and touted the size of my brain in the eyes of my 500 friends. Well, Kanai et al.’s findings were not at all about its size; they were limited to very specific parts of it. Yet I must admit that I maliciously took advantage of the ignorance of some of my mates. Their reactions to my childish post were various: some of them made fun of me, some pretended to be impressed. There was inevitably a bunch of them to criticize the findings as well as my own 'interpretation' of the results. Eventually, there were also a significant number of people who threatened my concept of 'friendship'. After all, how could I have 500 real friends when, as everybody knows, one can only maintain about 150 social bonds? Even Britney Spears knows that. Rumor has it that she chose to join the social network Path where the number of interactants is limited to 150. Why 150? Path’s cofounder Dave Morin justifies this limit by quoting Robin Dunbar's work on the social brain hypothesis: this is our 'social ceiling'. One cannot maintain approximatively more than 150 trusted relationships.

Here is the rationale behind this claim.

A debate on Robin Dunbar's social brain hypothesis

 

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

Part 1Part 2Part 3

 

Some months ago, an article by Jan de Ruiter, Gavin Weston and Stephen Lyon appeared in American Anthropologist. The paper's target is Robin Dunbar's Social brain hypothesis. The hypothesis comes in many varieties; one might sum it up as the view that our cognitive capacities keep the amount of friends we can have under a fixed threshold, and constrain the size of primate societies. (This summary is inadequate in many ways, as I hope this debate will show.)

Dunbar's hypothesis is one of the most popular piece of cognitive anthropology out there. It is also one of the most criticized in anthropological circles. Our site wouldn't be true to its vocation if it did not invite all the protagonists to an open debate. 

This week, Jan de Ruiter and his coauthors, as well as Robin Dunbar, will react on two posts, one defending the social brain hypothesis (posted today), the other defending the critics (to appear wednesday). Everyone from the ICCI community is welcomed to chime in.

Link to Jan de Ruiter et al.'s article.

Link to Robin Dunbar, 'The social brain hypothesis' (1998).

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