1. Biological influences on gender
Evolutionary explanations of gender roles

2. Learning objectives
Describe parental investments made by males and females
Explain how behavioural differences may have been linked to reproductive success
Understand the criticisms that have been made of the evolutionary account of gender differences

3. Introduction Gendered behaviour has roots in past
Result of sexual selection
Exist to enhance men and women perform particular roles necessary for survival.
Criticised by feminists
Agreement with biological perspective (nature rather than nurture)
Reproductive success is all important.

4. Parental investment theory
Trivers (1972)
Behavioural differences evolved due to different reproductive strategies which led to reproductive success in the past.
Males invest relatively little in parenting compared to females.

5. Difference in behaviour
Uncommitted sex / promiscuity = optimal strategy for males
Choosiness = optimal strategy for females.
Men and women differ in their readiness to engage in casual sexual encounters.

6. Parental investment theory also explains tendency to form relationships or ‘pair bonds’.

7. Differences in aggression
Men have to compete to be chosen
They need to be seen as fitter and stronger
Men tend to be bigger than females (the protector and provider).

8. Commentary and evaluation
It is unlikely that a one-night stand or short-term relationship will result in pregnancy.
A baby with one parent has less chance of survival.
This is an argument against the idea that promiscuous sex is advantageous to males.

9. Evaluation
The reluctance of women to engage in casual sex may reflect cultural views rather than biology and evolution.
Cassidy (2007) argues that evolutionary psychology tells us nothing about non-heterosexual relationships.
Differences may be undesirable (e.g. the idea of the uncommitted male).

10. Controversial aspects
The theory has been used to explain (justify) sexual violence such as rape.
This attracts much outrage and criticism. Does that necessarily make it wrong?
It is a sensitive area.