ABSTRACT
The most common and universal response to the actual or suspected extradyadic sex of a partner is jealousy. Indeed, infidelity by one's partner, and even the thought that such infidelity might occur, may often evoke intense and aggressive jealousy. Even more, in all cultures, and in all periods of history jealousy seems to have been acknowledged as one of the most destructive experiences in love relationships. This chapter focuses on sex differences with respect to extradyadic sex and jealousy. It examines what extent sex differences that have been demonstrated in empirical research can be interpreted from an evolutionary perspective. Evolutionary psychologists have suggested that because of men and women's different reproductive biology, men and women can differ psychologically in the cues that elicit jealousy. Feelings of jealousy are in part evoked through a process of social comparison, in which jealous individuals compare their own characteristics with those of the rival.
