Mate guarding behaviour in males is much more likely to be elicited by the threat of sexual infidelity in a female partner, in comparison to emotional involvement outside the mateship.[3][4] This is primarily due to the risk female infidelity poses for male paternity, or ‘genetic cuckoldry’.[2] In other words, as fertilisation takes place within females, males do not have paternal certainty in the way that females do (females can always be certain that the offspring is theirs, whilst a male cannot). There is supporting evidence for this cross-culturally in a varied range of countries such as China, Germany, Japan and Sweden.[5] Moreover, in physiological tests such as skin conductance and heart rate, men show greater levels of distress when asked to imagine a partner having sexual intercourse with another person.[6]
It is also worth noting that mate guarding tactics are more likely to be used if the partner is of high reproductive value e.g. if the female displays signs of high fertility such as youth and physical attractiveness.[7]
If a male does not successfully prevent a rivals’ attempt at mating, there are many risks. If the female becomes fertilised, then the male loses the opportunity to reproduce with that partner for an extended period of time and his genes will not be passed on to the offspring. Moreover, the male may invest years of time, resources and energy into a child that is not genetically his own.
If this becomes public knowledge, the individual may also face public humiliation, and as a result this could reduce his social status and affect his future chances to reproduce. There are also ‘opportunity costs’; wherein the male could have been spending lost time pursuing alternative mating options.[2]
Male mate guarding behaviour also needs to ensure that the female does not leave the mateship as this would reduce future chances the male may have to reproduce. Moreover, the male would also lose any maternal efforts the female would have invested in any potential offspring.
Additionally, access to any social benefits or helping networks that the female brought to the relationship could be lost. Finally, the female could also use information, such as strengths or weakness, about the male to exploit him in the future.[2] ]