1. Biological influences on gender

2. Relationship between sex and gender
Biological approach
Biological sex produces gendered behaviour.
Men = masculine
Females = feminine
Because of genes and hormones etc.

3. Deterministic No room for flexibility or choice
Programmed by biological factors.
The sex of a baby is determined at the moment of conception.
An embryo has 23 pairs of chromosomes, each made up of one from the ovum (mother) and one from the sperm (father).

4. The 23rd pair of chromosomes determines the sex of the embryo.
If the embryo inherits an X chromosome from the mother and a Y chromosome from the father, it will develop as a male.

5. Between 4 and 8 weeks after conception, the gene on the 23rd chromosome instructs the gonads to release hormones.
In the male embryo, the testes are instructed to release testosterone which acts on an area of the brain known as the hypothalamus. Without testosterone, the brain would develop in the female form (Green, 1995).
In the female embryo, hormone release from the ovaries is very slight.

6. In the brain

7. Sexually dimorphic nucleus located in the hypothalamus
Clear differences can be seen in the brains of adult men and women, in the function and anatomy of the hypothalamus.

8. Brain difference 2 Lateralisation in male and female brains.
Information passes between hemispheres through the corpus collosum.
Research found – when doing a language task, women used both hemispheres
Men only used the left.

9. Analytic thought
Logic
Language
Science and math
Holistic thought
Intuition
Creativity
Art and music

10. Genetic conditions Usual pattern is XY
One in 500 men have XXY pattern.
Unusually tall, enlarged breasts, likely to be infertile.

11. Genetic conditions continued
XYY male
One in a thousand males
Taller than average
Possibly more aggressive

12. Genetic conditions continued
Inter-sexed babies
Characteristics of both sexes
E.g. one ovary and one testis.
Very rare

13. Hormonal influences Androgens = male hormones
Oestrogens = female hormones
Everyone has both
Balance is important

14. Evidence for effect of hormones
Young (1966)
Doses of male hormones to female rats and female hormones to male rats
Resulted in a reversal of mating positions
Female rat takes the lordosis position when mating

15. More evidence Quadangno et al (1977)
Female monkeys exposed to testosterone in utero
More aggressive than other females

16. Case study evidence Money and Erhardt (1972)
Group of girls exposed to high levels of androgens in utero
More tomboyish, higher IQs and ambitious.

17. Congenital adrenal hyperplasia
Exposure to high levels of male hormones in embryo stage.
Hines (1994) compared girls and boys with CAH to unaffected boys and girls.
Not much difference
CAH girls preferred playing with boys

18. David Reimer
Born male
Raised female after his penis was accidentally burnt off during circumcision
Did not successfully identify as female

19. Correlational studies
Deady et al. (2006)
Negative correlation between levels of testosterone in women and scores on BSRI for maternal drive.

20. 2D:4DR Mixed findings on finger ratio (2D:4DR)
Significant findings in males – more feminine sex role on BSRI had a finger pattern which showed lower exposure to androgens and higher to oestrogens in utero.

22. To evaluate Consider the nature/nurture debate
How strong is the evidence that biology has an effect on gender?
Consider the studies you have looked at in terms of the reliability of the findings and the methodology used.