Cooperating with other people makes many things easier. However, competition is also a characteristic aspect of our society. In their struggle for contracts and positions, people have to be more successful than their competitors and colleagues. When will cooperation lead to success, and when is egoism more effective? Scientists from the Max Planck Institute for Evolutionary Biology in Ploen have developed an experiment that enables them to examine the success rate of cooperative and egoistic behaviour strategies. A strategy referred to as "extortion" is particularly successful, according to the researchers. This strategy that alternates between cooperation and egoism is difficult for the co-player to resist. The extortion strategy is especially effective when there is strong competitive pressure – that is if there can be only one winner.