E-Mail IMAGE: Direct reciprocity: First, Blue helps Red. In the next evolutionary step in the simulation, Red remembers that and now in turn helps Blue. Indirect reciprocity: First, Blue helps Violet and... view more Credit: Laura Schmid Cooperation as a successful strategy has evolved in both nature and human society, but understanding its emergence can be a difficult task. Researchers have to abstract interactions between individuals into mathematical formulas to be able to create a model that can be used for predictions and simulations. In the field of evolutionary game theory, they often investigate strategies of players in a simple game of giving and receiving benefits. Such strategies tell players how to behave in a given interaction. The scientists' findings counter the narrative that only the strongest and most selfish flourish and survive. Instead, they show how cooperation can be a successful and stable strategy.