Biological influences on gender

First 40 days after conception, embryos develop in the same way and have female and male anatomy If ovum is fertilised by a sperm carrying another X chromosome, the gonads develop into ovaries.

The male elements of anatomy disintegrate; the female ones thicken and grow into a womb. The external anatomy develops into female genitalia. If the ovum is fertilised by a sperm carrying a Y chromosome, the gonads cells convert into testes. The male internal organs develop and the female organs disintegrate.

External male genitalia develop. All human embryos would develop into females unless they are masculinised by the Y chromosome. Hormones:

After the sex chromosomes, the hormones provide the main biological influences on sexual differentiation. Males and females produce androgens The male hormone is testosterone The female hormones are oestrogen and progesterone Hormone levels can be taken as a measure of masculinisation and feminisation Under/over exposure to hormones during the critical period (6 to 8 weeks) can affect later gender related behaviour; boys exposed to too little testosterone may become less masculine and girls exposed to large amounts of testosterone may be more masculine.

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Hormones from the gonads influence the development of genitalia, the brain and gender behaviour. By week 8 of gestation, the gonads are producing hormones.

It is hard to establish hormonal influences on behaviour because there are other influences that affect our behaviour such as the nature, nurture debate Brain differences: Clear differences can be found in the brain function of adult men and women, particularly the function and anatomy of the hypothalamus, these difference however are not found in children under 6 years old Green (1995) states that testosterone may affect other brain structures such as those which influence aggressive behaviour, no direct evidence has been found

The degree of lateralisation in male and female brains is another difference.

The left hemisphere controls speech and language while the right hemisphere controls spatial skills with information being passed between hemispheres through the corpus coliseum. Shaywitz & Shaywitx (1995) used MRI scans to examine the brain whilst men and women carried out language tasks. Found that women used both hemispheres o the brain whereas men used the left hemisphere studies that support, with evaluation points

There are four sources of evidence to assess the link between biology and gender behaviour; animal studies, case study research, correlating hormone levels and gender behaviour. animal studies: young (1966) studied rats, a species where male and females show very different sexual behaviours males mount from behind and females adopt the "lordosis" position (back arched, head low) gave doses of male hormones to female rats and vice versa during critical period found that they showed reverse behaviours, males adopted the "lordosis" position and females attempted to mount from behind supports the idea that hormones are responsible for deciding male/female mating behaviour Animal studies evaluation points:

- The issue of the use of animals in research, is it ethical? unethical to......... it is ethically wrong to inflict such pointless suffering upon any living creature. Either animals are so dissimilar to us that we cannot logically apply the results of animal tests to humans, or they are so similar that it is unethical to test upon them - cannot apply to humans and make generalisation because he anatomy of a rat is very different to the anatomy of a human.

Cannot assume that humans would show the same results. There is no way to really know because it would be extremely unethical to manipulate hormones into humans during the critical period. we have to use case studies, like the young study, and wait for them to occur naturally +supports biological approach, shows that hormones are responsible for gender behaviour +it is a lab experiment, which means that there is lots of control and variables can be controlled, it also means that it is very reliable as it is a scientific experiment..... + which lead on to the fact that the experiment is replicable, not a lot is needed to carry out the experiment, just rats an hormones then all that you need to do s observe the rats Case study research:Money & Erhardt (1972)

1 sister was exposed to male hormones in utero compare to sister who was not mother was asked to comment on games played, toys used and clothing choices exposed girl = boyish girls, higher IQ and career aspirations follow up in 1974 showed only one difference in girls is that the exposed girl was more physically active Money and Erhardt evaluation points::

- Many of the questions asked were leading questions “ which of your daughters is the most tomboyish?”, the researchers may have used these to get a particular type of answer - follow up study in 1974 found only one difference, that the exposed girls were more physically active + Natural experiment..., ethical, high ecological validity

+ supports biological approach, although there is not strong evidence there still is evidence to show that there is a link between biology and gender behaviour - because the mother was told that her child is going to be more interested in boyish activities, she could have unintentionally encouraged more boyish behaviours onto her daughter Hines (1984)

3- 8 year old boys and girls with congenital adrenal hypersia (CAH) examined the amount of rough and tumble play compared them to an unaffected control group
found minor difference between CAH girls and control group girls CAH girls preferred playing with boys in 2004, compared 25 men and women who had CAH with their unaffected relatives both groups asked to think back and recall childhood gender role behaviour women with CAH recalled more "boy related behaviours" boys with CAH were no different to their unaffected male relatives

Hines evaluation points: + natural experiment, nothing was forced + used a control group, shows comparison+used both males and females, no gender bias +ethical....... because it is natural experiment -lacks population validity, does not say how many ppts in 1994 study and only 25 ppts in 2004 study -ignores environmental factors influencing behaviours, such as sibling and role models -showed only limited evidence supporting the biological approach correlating hormone levels and gender behaviour in normal populations:

Deady et al looked at relationship between gender role orientation an testosterone levels in child free young women asked ppts to complete SRI and asked how "broody" they felt and ideal age for having first child found women with high salivary levels of testosterone tended to have lower scores relating to the desire to have children lower maternal drives may be related to higher levels of male hormones Deady et al evaluation points

Only shows a link, no cause and effect +objective measure..... unbiased measurement/analysis, in that you measure what is there and not impacted by your beliefs or philosophy of something...that is for subjective measurement/analysis. The boy who was raised as a girl

Bruce and Brian, twins born in 1965
at 6 months old, the twins were circumcised
Bruce's operation was botched and his penis was all but burnt off went to Dr. John Money (who firmly believed gender was learnt) money advised that Bruce’s penis be removed so that he looked like a girl, and be raised as Brenda Brian the identical twin was the control

Brenda received female hormone treatments after being told the truth, Brenda instantly reverted to his true sex Boy who was raised as a girl evaluation points:
+ Biological sex is the primary factor contributing to a sense of gender.

Even when he though that he was a girl he still felt like he was the wrong gender, without even knowing that he was biologically male. + Case study, lots of information, detailed account, valid +supports that nature, nurture doesn’t have as much control evaluation of the role of genes and hormones +scientific approach to gender, gender -> biology -> science -> objective, sex/gender is the same +implications on real life situations, e.g. Olympics- compete with the gender that you identify with, genetic sex no longer determines gender +makes sense, we inherit other features such as hair and eye colour, why not gender features + lots of supporting evidence

1. animal studies
2. case studies say how it supports-> +&- of studies 3. correlation studies
4. boy who was raised as a girl

lots of supporting evidence, cannot generalise
too deterministic… gender= determined by your genes

ignores other factors that determine gender role behaviour e.g. role models, siblings, media, education reductionist, reducing behaviour down to genes, hormones and genes (biology) nurture, transgender, supports nurture behaviourist approach, gender is learnt other approaches, Freud, psychosexual stages