The Theory of Primate Sentiments: Part Two

time and group size.gif

The story so far.

Robin Dunbar is arguing that language developed amongst apes as something that could replace grooming in facilitating larger social groups than could be supported by grooming. Adam Smith is lurking in the background with the promise made that there are errie similarities between Smith’s view of the world and Dunbar’s. My brother makes a cameo appearance.

Here’s a potted description of how Dunbar reckons we came down from the trees literally.

1 Monkeys became able to deal with the tannins in unripe fruit, making life tough for the ancestors of apes and humans. Apes cannot digest tannin.

2 As a result of this and perhaps climate change, apes experienced increasing pressure to find food beyond the forest floor and they began venturing into the open plain. (I think it might have been easier for evolution to just let apes develop the enzymes to digest tannin but I’m always thinking this about evolution. It seems to underdetermine every explanation. Dunbar didn’t answer this little puzzle and we proceed for want of an alternative, assuming that nature works in mysterious ways).

3 The plains were full of dangerous predators and one of the ways we survived was building larger social groups. The diagram at the head of this post illustrates Dunbar’s accompanying theory that group size gradually rose as humanity emerged from its knuckle dragging ancestry. Standing erect also helped people see predator threats and kept them cooler with more ventilation and less area for the sun’s rays to hit.

4 Brains take up a huge amount of energy ours takes up 20% of our energy compared with body weight of around 2% of body mass. Why did we suffer this drag? According to Dunbar it was the only way that larger social groups could be maintained. We sacrificed by making other organs more economical particularly our stomachs which, could contract given the increased meat in our diet. Meat takes less digestion to convert to energy than much vegetarian fare.

Theory of Mind

The most central thing in the development of the brain, increasing the size of the social unit and the co-evolution of language and brain size is the development of ‘a theory of mind’.

A ‘theory of mind’ can be explained in terms of the concept of ‘intensionality’. My own beliefs constitute first order intensionality. My beliefs about your beliefs constitute second order intensionality. And my beliefs about your beliefs about me (or something else) demonstrate third order intensionality. A knowledge that another’s beliefs may be false is either a kind of two and a half order intensionality or fully third order intensionality if the truth or falsity of a belief is a belief about what’s going on in another mind.

Now you need second and perhaps two and a half order intensionality for trickery to develop. And guess what? Monkeys but particularly the higher apes are the only animals where there is substantial evidence of tactical deception Dunbar’s book is full of them.

(Our family has a famous story of tactical deception. When my brother and I were young kids we went to Taronga Park Zoo and a very clever little monkey engaged my brother in the ritual of feeding him peanuts. He put out his left hand and David became so entranced by the idea of putting one or two peanuts into his inviting hand time that the monkey was, shortly afterwards able to use its other hand to snatch the whole bag from whence the peanuts were coming. David’s exposure at a young age to the injustice of second order intensionality became a sufficiently emotional experience to be remembered over four decades later. My father chuckled to himself for a large part of the rest of the day and indeed possibly the week.

Understanding that what’s going on in others’ minds might be at variance with the truth requires third order intensionality and this is only practiced rarely and imperfectly in the animal world.

Thus in one experiment food was put in only one of several opaque boxes. The subjects of the experiments (monkeys, apes and humans) had to choose an assistant to help them identify which box to open, and they had observed one of the assistants being present when the food was placed in the box whilst the other was not. Most, but not all of the chimps in this experiment worked out to ask the assistant who’d seen which box the food was put, whereas none of the monkeys did.

About another slightly more complex experiment Dunbar says this.

Although the chimps did better than the autistic adults at this task, they were nowhere near as good at it as five and six year old normal children (who have theory of mind). The chimpanzees certainly learned to solve the problem, but they weren’t as competent as one might have expected had they had full theory of mind. (p. 100)

And it is this third order intensionality that Dunbar identifies as uniquely human and co-evolving with language and with gossip as the social cement replacing grooming as the engine behind human evolution.

Theory of mind is, beyond question, our most important asset. It is a remarkable skill. Yet even ToM pales into insignificance by comparison with where this skill has taken us.

ToM has given us the crucial ability to step back from ourselves and look at the rest of the world with an element of disinterest. The starting point of all this was probably our ability to reflect back on the contents of our own minds. Why do I feel the way I do? Why am I angry now? . . . Understanding our own feelings is crucial to understanding those of other people. Without recognizing what we are seeing in others, we have no hope of delving into their minds sufficiently far to appreciate their mental reactions to the things they experience.

The real breakthrough is where fully developed third-order ToM allows us to imagine how someone who does not actually exist might respond to particular situations.

Dunbar develops this thought in the direction of culture and literature. I preume Smith wouldn’t disagree with this, but in his hand, what Dunbar calls “Theory of Mind’ becomes a theory of the ‘natural’ ethical relations within human society based on their ‘moral sentiments’.

Not only does Smith have people’s individuality grow within a social setting. It is sympathy precisely the realisation of third order intensionality (that others look upon us as we do upon them) that is the engine of human society and indeed of the evolution of human consciousness.

Thus for instance Smith writes

We can never survey our own sentiments and motives, we can never form any judgement concerning them; unless we remove ourselves, as it were, from our own natural station, and endeavour to view them as at a certain distance from us. But we can do this in no other way than by endeavouring to view them with the eyes of other people, or as other people are likely to view them. Whatever judgement we can form concerning them, accordingly, must always bear some secret reference, either to what are, or to what, upon a certain condition, would be, or to what, we imagine, ought to be the judgement of others.

In the next exciting instalment – a postscript really – we learn about Adam Smith’s own theory of the evolution of language and how his general approach to the evolution of language has deep similarities with his explanation of the evolution of markets and of morals.

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17 years ago

i like these posts, I can get on my hobby horse.

I think it might have been easier for evolution to just let apes develop the enzymes to digest tannin

we cook it. e.g. chestnuts

‘theory of mind’ etc

Same process as to how we negotiate deals too, divisions of labour are negotiated socially, ie they are created by social acts, the economy is a social construction, as is the individual, and the resulting economic benefits (specialization’s material rewards) can then leverage new ‘markets’ (new landscapes and bodies composed from the substrate/terrains that were so recently made landscapes).

When we learnt, and learnt how to pass on the knowledge of, how to hunt AND gather we could do anything.

Now that’s social capital.

Joshua Gans
17 years ago

I’ve enjoyed these two posts, Nicholas, and look forward to meeting the grand theory in Part 3. Three questions:

1. I knew there was a word intension as distinct from intention. But isn’t it a technical term in linguisitics having to do with the scope of a word’s meaning? This seems remote from Dunbar’s topic. Does he comment on this?

2. How exactly is group size relevant to brain power, imagination and so on? Antelopes have quite sophisticated group coordination for protection against predators, but they’re not as clever as whales, who don’t have nautral predators and are basically solitary as far as I know.

3. My students have just been reading an article by D.Gruen on fiscal policy. Can I tell them the monkey story?

17 years ago

“I think it might have been easier for evolution to just let apes develop the enzymes to digest tannin ”

It probably would have been, but you can’t choose what mutations your species will experience.

It probably would have been even better for Apes to grow bat-like wings and take to the skies. The mutation they got was a bigger brain, so they had to make the best of it.

Chris Lloyd
Chris Lloyd
17 years ago

I saw a very funny video last year which involved a chimp playing some kind of simple game with his handler. It was a game that involved moving blocks and was itself pretty sophisticated. Anyway, a second handler deliberately distracted the chimp which gave the first handler a chance to swap and change some of the pieces. When the chimp returned to the game he quickly realised that the pieces had moved. His face changed from puzzlement to shocked disbelief as he realised that the handler had cheated. He stared at the handler is horror with his mouth open in a wide “oh!” and then proceeded to throw a tantrum.


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