Numerous studies have shown that men experience relatively greater levels of jealousy in response to the sexual aspects of an infidelity (relative to women), whereas women experience relatively greater levels of jealousy in response to the emotional aspects of an infidelity (relative to men). The traditional explanation for this relationship suggests that men experience this greater level of jealousy due to threats of a loss of paternal certainty. In this article, we present three studies that demonstrate that men's differentially greater jealousy occurs in response to situations that threaten paternity opportunities. These results suggest that a loss of perceived paternity opportunities is the ultimate origin of men's increased jealousy in response to sexual infidelity.
Keywords: Sex differences; jealousy; paternal uncertainty; paternity opportunities.