Abstract
Modern evolutionary psychology provides a cogent criterion for considering an emotion as “basic”: Whether the emotion evolved to solve an adaptive problem tributary to reproduction. Criteria such as distinctive universal signals, presence in other primates, or contribution to survival are not relevant, even though some basic emotions have these properties. Abundant evidence suggests that sexual jealousy is properly considered a basic emotion, even though it lacks a distinct expressive signature, contributes to adaptive problems of mating rather than survival, and may or may not be present in other primates.