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.
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.
"The two prisoners that are interrogated are not allowed to talk to each other. If they did they would make a pact and be free within a month. But if they were not talking to each other, the temptation would be to rat the other out.
"Being mean can give you an advantage on a short timescale but certainly not in the long run - you would go extinct."
These latest findings contradict a 2012 study where it was found that selfish people could get ahead of more co-operative partners, which would create a world full of selfish beings.
