Researchers have for the first time explained how language develops in large groups of unrelated people, without allowing some members of the group to cheat others.

While language plays a key role in enabling individuals in a society to cooperate through the coordination of activities, it also makes it possible for some individuals to benefit unfairly off the hard work of others.

This has posed a problem for biologists, of how language evolves in a way that ensures that the few don’t take advantage of the many - especially where individuals are unrelated and where there would be no genetic reward for those doing the bulk of the work.

Researchers at the University of Oxford have now examined the origins of language in a study published in the journal Royal Society Open Science, answering the questions of how language evolves and why it is so rare among animals, even among those that do have complex social groups.

The team devised a mathematical model to see how receiving new information affected the time it took a group of individuals to solve a problem. They took into account variables such as the number of individuals, how often they interacted, and the size of the reward for the individual and the group.

By observing the volume of vocal communication - or chatter - as well as the precision of the information being conveyed, the team modelled the evolution of language development over time in the simulated group. This also affected how large the group could become.

They found that as chatter became less regular, but more precise, the group size could increase because of better coordination. However, the model also showed that although the volume of chatter naturally decreased in a simulated group over time, it took longer for this lower volume of noise to be replaced by an increase in precision of transferred information. This indicated that while basic communication can evolve quickly, more complex language takes time to develop.

Lead author, Tamas David-Barrett of the University of Oxford’s Experimental Psychology division, said: ‘Language allows groups to coordinate collective action efficiently. Usually with public goods there is a free rider problem, as individuals have an incentive to cheat for personal gain. In the case of language this is usually looked at in terms of the content of the communication. In this paper, we look not at the content of communication, but at the fact that language as a means of communication exists at all.

‘Language would be a natural candidate for the free rider problem because efficient communication benefits the group’s coordination effort, but comes at a high cost to the individual - it requires an expensive brain and a costly physiological machinery.

‘We show, however, that the evolution of language avoids the free-rider problem if the individual has an interest in being linguistically aligned with the group, receiving a direct benefit from being able to communicate. The implication is that language is likely to have evolved slowly, as there is no point in being a much better linguist than the others in your group.’

Professor Robin Dunbar of the University of Oxford’s Experimental Psychology department, explained: 'The evolution of both language and cooperation has been a major puzzle for evolutionary biologists. For the first time we have offered a coherent explanation for both that gets around the problem that all previous explanations have faced – why individuals didn’t cheat on this cooperative arrangement.

‘Social groups have evolved for coordination rather than cooperation - behavioural coordination allows groups to stay together rather than drifting apart, enabling the group to function as a defence against predators. This by-passes the usual freeloader problem that most analyses of the evolution of cooperation face when individuals have to pay a price to benefit from cooperation.

‘In this case, individuals are either members of the group or not, and benefit accordingly. There is no price you pay to benefit, other than being able to communicate well enough to coordinate group movements.’

The full paper, ‘Language as a coordination tool evolves slowly’, can be read in the Royal Society Open Science journal.