Human sense of fairness evolved to favor long-term cooperation ["the evolution of fairness"] Brosnan and de Waal hypothesize that individuals should be willing to give up a benefit in order to reach equal outcomes and stabilize valuable, long-term cooperative relationships . Thus far, this has only been found in humans and their closest relatives, the apes. "Giving up an outcome that benefits you in order to gain long-term benefits from the relationship requires not only an ability to think about the future, but also the self-control to turn down a reward ," Brosnan said. "These both require a lot of cognitive control. Therefore, we hypothesize that lots of species respond negatively to getting less than a partner , which is the first step in the evolution of fairness , but only a few species are able to make the leap to this second step, which leads to a true sense of fairness."
