Sex Differences in Jealousy: Evolution, Physiology, and Psychology

TLDR

In species with internal fertilization, male jealousy protects paternity while female jealousy guards against rivals diverting partners’ resources. The authors tested whether sex differences in jealousy evolved as adaptive responses to the distinct reproductive challenges faced by males and females. They conducted three studies: a choice task comparing reactions to sexual versus emotional infidelity, a physiological measurement of responses to imagined infidelity, and an examination of how committed relationships modulate jealousy. All three studies revealed pronounced sex differences, supporting the hypothesis that jealousy functions differently for each sex.

Abstract

In species with internal female fertilization, males risk both lowered paternity probability and investment in rival gametes if their mates have sexual contact with other males. Females of such species do not risk lowered maternity probability through partner infidelity, but they do risk the diversion of their mates' commitment and resources to rival females. Three studies tested the hypothesis that sex differences in jealousy emerged in humans as solutions to the respective adaptive problems faced by each sex. In Study 1, men and women selected which event would upset them more—a partner's sexual infidelity or emotional infidelity. Study 2 recorded physiological responses (heart rate, electrodermal response, corrugator supercilii contraction) while subjects imagined separately the two types of partner infidelity. Study 3 tested the effect of being in a committed sexual relationship on the activation of jealousy. All studies showed large sex differences, confirming hypothesized sex linkages in jealousy activation.