Jealousy is a complex emotion motivating important aspects of human behaviour and with a significant role in narratives from all human cultures. Furthermore, because it often leads to violence, jealousy also carries legal and moral implications. Though the concept of jealousy was often broached in literature, philosophy and psychology, modern evolutionary theory provides detailed testable hypotheses about the origin of this emotion, its role in mating strategies and eventual differences between male and female jealousy. Such evolutionary insights can enrich and correct traditional interpretations of this emotion. This chapter covers hypotheses regarding the evolution of human jealousy, particularly in the context of long-term committed mating strategies; outlines different proposed explanations; and confronts them with the available data and traditional views on jealousy, both in science and literature. Finally, this chapter explores how understanding the evolutionary causes of jealousy can inform our social and moral responses to this emotion.