Altruism generally refers to behavior that is at a cost to oneself but beneficial for another person. From the point of view of economics as well as evolutionary biology, altruism is a conundrum. Behavior at the expense of oneself and for the benefit of another should not emerge if, ultimately, each individual seeks the best for himself or herself (i.e., following the evolutionary principle of “survival of the fittest”).

Nevertheless, it is easy to observe acts of altruism (or prosocial behavior) in the world, and not only among humans. Animal parents will defend their offspring just as much as human parents selflessly support their children (i.e., kin selection). But apart from direct family, we can also frequently observe people giving to charity, strangers helping one another, ...