Jealousy is defined by Daly, Wilson & Weghorst (1982) as a “state that is aroused by a perceived threat to a valued relationship or position and motivates behaviour aimed at countering the threat”. There is empirical support to suggest that there is sexual differentiation in responses to scenario’s which elicit jealous reactions (Pietrzak, Laird, Stevens & Thompson, 2002). In a study conducted at the Australian National University in 2000, more men than women endorsed sexual infidelity as most distressing. The type of infidelity found more distressing to males and females is explained and justified by the evolutionary hypothesis (EH). It suggests that sex differences have their origins in the evolutionary process and are to be found universally (Buss, Larsen & Westen, 1996). Conversely the double-shot hypothesis (DS) suggests that men and women select the more distressing type of infidelity they think implies the occurrence of the other. Finally proponents of each hypothesis point to results and methodological deficiencies of the other hypothesis to undermine its claims. Although both hypotheses have reason to be believed the latter seems to be displaced by the amount of compelling evidence which suggests that sex differences have their origins in an evolutionary process that results in the different reactions to infidelity shown by men and women. (more…)