Evolution of revealing emotions

This paper develops an evolutionary approach to investigate whether revealing one's own emotions such as selfishness, altruism or envy has evolved in humans through a process of natural selection. This paper finds two results. First, if the revealing trait (revealing or hiding) and the other-regarding trait (selfish or altruistic/envious) are independent so the four types evolve in a correlated way, both of revealing types and hiding types can survive in the long run. For most parameter values, however, revealing altruism fares better than hiding altruism if individuals’ interactions are strategic complements, whereas hiding envy fares better than revealing envy if individuals’ interactions are strategic substitutes. Second, for most parameter values, only the revealing types survive if the revealing trait and the other-regarding trait are linked so that the four types evolve independently.