Male sexual jealousy functions to defend paternity confidence,[REF] and is likely to have evolved through natural selection[REF] to prevent cuckoldry - a threat to males since they could be investing in offspring they are not biologically related to.
From an evolutionary perspective, the jealousy arises from this threat of investing in non-biologically related offspring and thus is most strongly felt over their mate's sexual infidelity than their emotional infidelity [REF].