Critically consider evolutionary explanations of sex differences in parental investment. (24marks)

However parental investment has changed partially in the Western society as most investment is shared between males and females. For example helping out more at home, so changing nappies and feeding the babies.

In conclusion to the previous theory about females investing more that males by Trivers (1972) this might not be true as men might not put in the physical in the pregnancy but they may be on the same level emotionally. Trivers continues to suggest that even though he thinks females invest more, men still do invest, but they do later on, making up for the physical after the birth so forming the attachment with the offspring after.

Trivers theory is a very positive explanation because it does offer a way of explaining  parental investment, sexual selection and mating behaviour. Differential parental investment by males and females means that men stand to gain from polygyny  whereas women have more to gain from monogamy. In other history and other cultures polygyny was the common mating system as it meant more resources and provides more investment in her offspring and parental care, but since western influences it is not that common anymore.

Another parental investment is Paternal investment, human males can easily withdraw from parental investment in a way females cannot. Most male species can afford to devote a very little amount of parental investment because they use a large part of their reproductive effort on courtship and mating. This makes the female think that choosing a suitable partner is essential as this will mean a greater investment in their offspring, they feel there is more to lose if they do not achieve this. Trivers assumption about females giving greater potential investment can be then challenged by Anderson et al (1999). Anderson claimed that men nay invest in step-children in order to convince the mother they are “good providers” thus promoting future mating possibilities.