Selfish traits not favoured by evolution, study shows

Evolution does not favour selfish people, according to new research.

This challenges a previous theory which suggested it was preferable to put yourself first.

Instead, it pays to be co-operative, shown in a model of "the prisoner's dilemma", a scenario of game theory - the study of strategic decision-making.

Published in Nature Communications, the team says their work shows that exhibiting only selfish traits would have made us become extinct.

Game theory involves devising "games" to simulate situations of conflict or co-operation. It allows researchers to unravel complex decision-making strategies and to establish why certain types of behaviour among individuals emerge.

Freedom or prison
A team from Michigan State University, US, used a model of the prisoner's dilemma game, where two suspects who are interrogated in separate prison cells must decide whether or not to inform on each other.

In the model, each person is offered a deal for freedom if they inform on the other, putting their opponent in jail for six months. However, this scenario will only be played out if the opponent chooses not to inform.

If both "prisoners" choose to inform (defection) they will both get three months in prison, but if they both stay silent (co-operation) they will both only get a jail term of one month.

The eminent mathematician John Nash showed that the optimum strategy was not to co-operate in the prisoner's dilemma game.