Biological Explanations of Gender Development
Psychology: AQA A Level, topic 10.1.3
Testosterone Production and Brain Development
Testosterone from fetal testes drives male physical and brain development, but structural differences rarely lead to functional differences between sexes.
Biological explanations
- Biological explanations examine how chromosomes and hormones influence psychological and behavioural traits.
- This includes sex-typical behaviours, such as tendencies associated with masculinity and femininity.
Testosterone
- Testosterone is a sex hormone found in higher levels in males.
- Testosterone is produced by the fetal testes in males during development.
- Testosterone influences the development of male physical characteristics such as genitalia, muscle growth, and secondary sexual traits.
Foetal development
- Early in development, all foetuses have similar reproductive structures.
- Presence of a Y chromosome activates a gene that triggers the formation of male genitalia.
- In the absence of this gene, female genitalia develop, and testosterone production is minimal.
Brain structure
- Testosterone affects the developing male brain, leading to structural differences compared with female brains.
- However, these structural differences do not necessarily translate to functional differences in behaviour.
Hyde (2005)
- A review of meta-analyses conducted by Hyde (2005) found that there was a very small or no difference between the sexes on a majority of measures.
- In other words, males and females differ psychologically very little.
- Other researchers believe that the combination of sex hormone differences and structural differences result in similar brain function in both sexes.
Genetics
- Testosterone production may or may not be what leads to differences in biological sex. There is another explanation.
- Laboratory studies conducted on animals shows that differences in sex are not explained by hormonal levels during that early brain development.
- It could be that sex differences are directly caused by genes.
Congenital Adrenal Hyperplasia (CAH)
Congenital adrenal hyperplasia (CAH) is a syndrome whereby more testosterone is produced than usual.
CAH
- Congenital adrenal hyperplasia (CAH) is a syndrome whereby more testosterone is produced than usual.
- It occurs in both genetic males (XY) and females (XX) with different effects:
- If men have CAH, they will have early sexual development but otherwise will not have much of an effect.
- If females have CAH, the increased amounts of testosterone will cause them to become masculinised.
Effects in genetic females
- Increased prenatal testosterone in females can influence sex-typical behaviours and physical development.
- Examples include accelerated growth, earlier puberty, and masculinised physical traits (e.g., increased muscle mass, deeper voice).
- CAH can cause ambiguous genitalia at birth, irregular menstrual cycle and potential fertility issues later in life.
Effects in genetic males
- Males with CAH may experience earlier sexual development and increased growth rate.
- Other physical development is generally typical.
CAH and the brain
- By studying individuals with CAH, scientists can better understand how sex hormones influence the brain.
- Increased testosterone may affect sex-typical behaviours, such as activity levels or preferences, but effects vary.
Test yourself on Biological Explanations of Gender Development
Who conducted a review of meta-analyses and found that there was a very small or no difference between the sexes on a majority of measures?
Which of the following is true of CAH?
Which is NOT a reason for the study of congenital adrenal hyperplasia?