Discuss sex differences in Parental Investment (24 marks)
The biggest and most apparent different in parental investment is that it is much easier for males to pot out o parental investment, than it is for women. Parental investment theory suggests that the sex that makes the larger investment (females) will be more sexually discriminating when choosing a partner. It also says that males, who are the sex that makes the smallest investment, have to compete for the highest investing females.
The investment made by females is considerably greater than the investment made by males. This may be because women produce much fewer eggs than males do sperm, therefor females have much fewer opportunities to reproduce than males. It may also be due to parental certainty, females definitely know that the child is theirs whereas males cannot be certain that a child is theirs. The higher investment by females may also be due to the act that the cost of childcare is far higher to women. For example Symons (1979) explain that the minimum cost to a women is 9 months of feeding and carrying a child, whereas or males the minimum cost is a few moments of copulation.
There is also an evolutionary explanation of parental investment. As a response to adaptive pressures faced by our distant ancestors, brain size increased. This resulted more difficult childbirth because of the enlargement of the skull. Consequently, human infants are born earlier and are therefor more immature at birth. Unlike other mammals humans often breastfeed their young, this shows that mothers have an extended period of childcare, therefor showing that women do not only have higher investment during pregnancy, but also have higher compulsory postnatal investment.