The Theory of Primate Sentiments: Part One.

Brain Size and social groups.gif

I’ve just finished reading a book entitled “Grooming, gossip and the evolution of language“ (Amazon link – but no pages to view) by Robin Dunbar a 1996 book written in a highly entertaining style for a lay audience. In my ignorance of the field, I found the book highly entertaining, fascinating and persuasive.

Why might I be interested in it?

Well I heard about it from Anna Gunnthorsdottir’s nomination of it in a popular article entitled “five books that can explain the games people play”. Anna is a behavioral economist who’s website describes her as interested in

  • Determinants of cooperation, defection, and reciprocity
  • Strategic deception, trust and cheating
  • Incentives that increase cooperation

That sounds interesting enough. But I’d like to add that the idea of feedback is of considerable interest to me. For me the subject of human consciousness as interactivity (rather than pure intellection) is a very interesting one. It ramifies through economics particularly Austrian economics though it has not been brought to the fore in the way information and incentives have. Thus neoclassical economists explain markets as dominated by trades of interest between the players. Austrian economists (or at least Hayek) add that trading of information is at least as important.

I think that interactivity the scope for agents in a market to influence each other is just as important. Smith is onto this which was part of my point in naming some previous posts on him Homo Dialecticus. So that’s what got me in. As I read the book I got quite excited. I don’t know how new Dunbar’s theory is, or how well regarded it is in its field. I’ve already found the odd counter-example to his evidence in some book reviews. But given how tenuously our picture of the evolution of language can be anchored to the evidence it seems to me that Dunbar’s approach is very persuasive.

Some readers will have already guessed from my title that there are some obvious parallels here with the Scottish Enlightenment thinkers, not least our friend Adam Smith. The Scotts were into what’s been termed ‘conjectural history’ where they speculated on the rise of civilisation and in particular offered scenarios of the history of humanity driven by particular universal principles. Robin Dunbar’s history of language is pretty conjectural too, though he’s got a lot more evidence to go on that the eighteenth century Scotts.

In any event, the story Dunbar tells rejects the idea that language evolved from warning cries regarding predators. (Some monkeys have ‘words’ in their calls for leopard, eagle etc a fact discovered not that long ago by playing the sounds back to the monkeys and noting that when one call was played [the call for a leopard], they run up trees, and when another call is played [the call for eagle}, they run down them!). Dunbar also rejects the idea that language evolved from the co-ordination of the hunt. Wolves and lions do a pretty good job of coordinating a hunt and they do it without language or particularly big brains.

Rather he argues that language evolved as a means of ‘leveraging’ the work in building primate social relations that was previously achieved by grooming. Grooming evolved he argues from its capacity to build social relationships. Grooming is time consuming and so, like the peacock’s tail, is in the first instance a disadvantage for species that practice it. But it is selected out because species that groom find ways to co-operate that are denied species that don’t groom. Grooming is typically done within close knit groups. Monkeys are not promiscuous with their grooming. To the contrary their grooming is a big investment in each other. So it is used to develop relationships in which each party has a sunk cost which protects against free riding, cheating and capriciousness. If you’ve built up a relationship with someone, you don’t want to trash the relationship and blow all that time you’ve invested.

An important part of Dunbar’s theory came into focus when he was participating in a debate about brain size, social development and the intelligence of different species. The problem was that large brain size doesn’t correlate all that well with intelligence and the size of social groups something that Dunbar sees as key.

Then he mapped the relative size of the neo-cortex in primates and bingo got the graph at the top of this post which shows a clear relationship between this the size of social groups.

. . . BE AMAZED AND LEARN in the next exciting episode . . . how, according to Dunbar’s theory, what made us human is the exact same thing that our trusty guide to life Adam Smith thought was the the thing that makes us human. There’s even a part three!

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9 Responses to The Theory of Primate Sentiments: Part One.

  1. meika says:

    moving on from grooming to language and culture (gossip by other means) the key thing to remember for our hominin expansion is that we know our species occupies more than one ecological niche (something economists have difficulty understanding because of the grooming games they play in politics with scientifically ignorant lawyers like the Prime Minister John Howard, they get the feedback from them that they are okay, good little lap dog).

    Hunting did not lead to big brains because hunting AND gathering lead to big brains because the division of labour was organised socially.

    (Simplistically thinking it was just hunting would be vey attractive to recidivists like alpha male lawyerly trained politicians rather than scientifically educated leaders)(yes I am trolling).

    Once we could organise day to day activities and develop ritual and ceremony to educate the young in handing on social technologies (like Jurkupa) to organise the day to day hunting AND gathering, we had it made.

    Because if we could learn AND teach a way of moving across the landscape then we could learn new ways in new places from savanah to jungles to glacial grasslands to the high artic.

    Not only that, when could apply the same skills in adaption to the resultant new landscapes that our cultures developed on these ‘old growth’ terrains (agriculture, bulk trade and nomadism being the two big ones) and we had large numbers of peoples settling or moving around these new landscapes become the terrain for new movements and so new social landscapes.

    For example the marketplace, the monastery, the big house, the temple, and the coffee house will come, and on top of them we will get stock markets and then weird differential schemes like the options market. Each more removed from the world of dirt beneath our feet. Virtual reality is a pure form of the all to human adaption of social negotiation/creation of multiple niches by one species.

    All because we are the only animal that has socially negotiated, and socially maintains through a cultural system best described I think by Mary Douglas which both supplies and maintains oppositoinally defined and rejecting thought styles which gives this social system the robustness to maintain a diversity of options in social circulation (ie some will appear non-rational to economists at certain times) but without which there would be no economy to study at all.

    The economic landscape is a derivative (however powerfully conditioning) of the social abilities we have to organise the day to day activities and be able to hand them on, this social ability (oh so much more than grooming) is itself a derivative of our basic physiological upbringing in an ecology.

    As ANIMALS. A psychological fact reduced by the religiously biased to soul.

    but it is good to see economists start looking at these things. Lazy lap dogs.

    Now where’s my dole check, I though I’d left it in my copy of The Prince, but…

  2. Patrick says:

    I think it is uncontestable that humans are social creatures, and that we evolved to the top of the tree by specialising in socialising.

  3. Rafe says:

    Nicholas, did Buhler’s theory about the levels of language get a mention? He identified three levels
    1. Expression, which simply reflects the state of the beast at the time.

    2. Signalling, where other members of the species are either wired or have learned to pick up a message from the sound – the most obvious are warning calls and mating signals.

    3. Descriptive. This is where things get really interesting, because the descriptive function is hard to find in animals, while humans do it all the time.

    There is a theory that the descriptive function evolved out of the play of young animals and also their interaction with their mothers (which would include grooming).

  4. Jim Birch says:

    You might try Six Impossible Things Before Breakfast, by Lewis Wolpert. On my reading so far, he takes the quite different position, that conceptual ability arose for tool making and use (conferring a massive evolutionary advantage,) and that language arose with conceptual ability. He brings a rich array of evidence to his arguments, which are not so much about language but about how belief works.

  5. It’s interesting. When I read Dunbar’s book I kept thinking of Robin Dunbar as a woman. Of course I wasn’t paying attention to the spelling of his name, but his theory is very much centred on the social work done by women as the agents of the evolution of language – though I never read it as self consciously feminist. I’ve not read Wolpert, but I’m skeptical. It seems to me that language is likely to lead conceptual ability. But then I confess I’m only guessing. Guess I should go and read the book!

  6. meika says:

    crows use tools so we’ll be outsourcing script kiddie work to them soon, I guess

  7. Patrick says:

    You might try a commentary on Wittgenstein, or his Philosophical Investigations.

  8. Jim Birch says:

    Apes use tools and will reuse tools that work but even simple modification of naturally occurring tools is rare. Some chimps will trim sticks used for digging out insects but fashioning tools for a purpose is limited. The use of tools by apes indicates – at times – a borderline level of insight into problems above mere associative learning.

    New Caledonian crows have possibly the most advanced tool use of any animal except humans. The crows manufacture and use complex tools including straight and hooked sticks and complex flat tools made from leaves. They are able to select correct length sticks from a set with significantly better than random frequencies for a task of removing food from perspex tubes. Significantly, they are able to do this on first exposure to a novel task, indicating a real level of causal insight into the problem.

    None of this compares with the ability of humans, even the very young, to modify found objects and combine materials into purpose-built tools. This doesn’t tell us much about the Philosophical Investigations issue but we don’t know for sure that Wittgenstein could bind a rock to a stick to make a club. He is alleged to have threatened Popper with a handy found object on one occasion, the “Wittgenstein’s Poker” incident, but there is no evidence of modification or enhancement of the poker.

  9. meika says:


    He is alleged to have threatened Popper with a
    handy found object on one occasion, the “Wittgenstein’s Poker” incident,
    but there is no evidence of modification or enhancement of the poker.

    Yes there was. It was used (modifying) for leverage in a social negotiation. Its just that the poker was the modification to a social situation.

    What was the outcome?

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