 Yet another area of discussion is  evolutionary game theory—an  application of the mathematical theory of games to biological and other evolutionary contexts. It has provided a source of putative explanations for human and other behaviors; evolutionary psychology, mentioned above, is one area that frequently makes use of a game theory approach. Among the more challenging behaviors that evolutionary game theory has sought to explain is  altruism.  With altruism, we again encounter questions about the level at which selection is operating (organisms or groups) because of questions about which entities selection is benefiting or harming. 