Discuss gender differences in parental investment (24 marks)
Parental investment is defined as "any investment by a parent in an offspring that increases the chance that the offspring will survive". There are several explanations of sex differences in parental investment. One is that that females typically invest more because they have already invested the most (Trivers, 1972). Females generally contribute a lot more to the physical development of children due to the burden of carrying them for nine months then the extensive breast feeding period afterwards. Buss (1989) found females select resource rich, ambitious men, supporting this idea and demonstrating how mate selection by females can enhance their parental investment by increasing the survival chances of their offspring.
Another explanation is that females invest more because males have less parental certainty; or that females are less likely to have more offspring in the future (Gross and Sargent, 2005). Gross and Shine (1981) found with internal fertilization that parental care is carried out by females in 86% species, while with external fertilization parental care is carries out by males in 70% of species, supporting these predictions based on paternal certainty. However, Krebs and Davies (1981) report that it isn’t always true that external fertilization leads to increased paternal certainty. In sunfishes, cuckoldry occurs during the female’s egg positioning.
Rowe (2004) suggests that an explanation of paternal investment based on evolutionary factors alone is severely limited. Mens parental behaviour depends on various personal and social conditions, including the quality of the relationship with the mother, the characteristics of the child and the personality characteristics of the father. Belsky (1991) also claims that childhood experiences such as parental divorce tend to correlate with the degree to which men invest in the upbringing and care of their own children.
The concept of...