Robin Dunbar

Grooming, Gossip and the Evolution of Language

These groups do not have a specific function: in one society they may be used for one purpose, in another society for a different purpose. Rather, they are a consequence of the fact that the human brain cannot sustain more than a certain number of relationships of a given strength at any one time. The figure of 150 seems to represent the maximum number of individuals with whom we can have a genuinely social relationship, the kind of relationship that goes with knowing who they are and how they relate to us. Putting it another way, it's the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar.

Thus it seems that, even in large-scale societies, the extent of our social networks is not much greater than that typical of the hunter-gatherer's world. We may live in the centre of enormous modern conurbations like New York or Karachi, but we still know only about the same number of people as our long-distant ancestors did when they roamed the plains of the American Midwest or the savannahs of eastern Africa. Psychologically speaking, we are Pleistocene hunter-gatherers locked into a twentieth-century political economy.

All this raises an interesting puzzle. Grooming seems to be the main mechanism for bonding primate groups together. We cannot be sure exactly how it works, but we do know that its frequency increases roughly in proportion to the size of the group: bigger groups seem to require individuals to spend more time servicing their relationships.

If this is so, then we have a problem. The largest typical group size (that is, the average for a species) is the 50-55 characteristic of baboons and chimpanzees, and they seem to be pushing at the limits of the amount of time that can be devoted to grooming without digging disastrously into ecologically more important components of the time budget (such as feeding and travelling time). If modern humans tried to use grooming as the sole means of reinforcing their social bonds, as other primates do, then the equation for monkeys and apes suggests we would have to devote around 40 per cent of our day to mutual mauling. Quite a thought—an almost continuous opiate high.

But no species that has to earn its living in the real world (as opposed to nipping down to the corner supermarket for the week's shopping) could possibly sustain such a heavy investment of time in grooming. It would starve in the process. And this raises an interesting thought about the way we establish and service our relationships. Our ancestors must have faced a terrible dilemma: on the one hand there was the relentless ecological pressure to increase group size, while on the other time-budgeting placed a severe upper limit on the size of groups they could maintain. It seems that somehow they managed to square the circle.

The obvious way, of course, is by using language. We do seem to use language in establishing and servicing our relationships. Could it be that language evolved as a kind of vocal grooming to allow us to bond larger groups than was possible using the conventional primate mechanism of physical grooming?

Language does have two key features that would allow it to function in this way. One is that we can talk to several people at the same time, thereby increasing the rate at which we interact with them. If conversation serves the same function as grooming, then modern humans can at least 'groom' with several others simultaneously. A second is that language allows us to exchange information over a wider network of individuals than is possible for monkeys and apes. If the main function of grooming for monkeys and apes is to build up trust and personal knowledge of allies, then language has an added advantage. It allows you to say a great deal about yourself, your likes and dislikes, the kind of person you are; it also allows you to convey in numerous subtle ways something about your reliability as an ally or friend.

Bonding is a tricky business, because you are committing yourself to a relationship with no guarantee that your partner will reciprocate. You are vulnerable to being cheated by free-riders, who exploit your good nature and then abandon you just at the moment when you most need their help. Being able to assess the reliability of a prospective ally becomes all-important in the eternal battle of wits. Subtle clues provided by what you say about yourself—perhaps even how you say it—may be very important in enabling individuals to assess your desirability as a friend. We get to know the sort of people who say certain kinds of things, recognizing them as the sort of people we warm to-or run a mile from.

Language has an additional benefit invaluable in these circumstances. It allows us to exchange information about other people, so short-circuiting the laborious process of finding out how they behave. For monkeys and apes, all this has to be done by direct observation. I may never know that you are unreliable until I see you in action with an ally, and that opportunity is likely to occur only rarely. But a mutual acquaintance may be able to report on his or her experiences of you, and so warn me against you—especially if they share a common interest with me. Friends and relations will not want to see their allies being exploited by other individuals, since a cost borne by an ally is ultimately a cost borne by them too. If I die helping out a scoundrel, my friends and relations lose an ally, as well as everything they have invested in me over the years. Language thus seems ideally suited in various ways to being a cheap and ultra-efficient form of grooming.

The conventional view is that language evolved to enable males to do things like co-ordinate hunts more effectively. This is the 'there's a herd of bison down by the lake' view of language. An alternative view might be that language evolved to enable the exchange of highfalutin stories about the supernatural or the tribe's origins. The hypothesis I am proposing is diametrically opposed to ideas like these, which formally or informally have dominated everyone's thinking in disciplines from anthropology to linguistics and palaeontology. In a nutshell, I am suggesting that language evolved to allow us to gossip.