AQA A-Level Psychology Topics: Gender
Another post in our series of blogs on Psychology A-level topics, today we consider gender.
People often get confused between the terms sex and gender. Sex refers to biological differences between males and females. For example, chromosomes (female XX, male XY), reproductive organs (ovaries, testes), hormones (oestrogen, testosterone).
Gender refers to the cultural differences expected (by society / culture) of men and women according to their sex. A person’s sex does not change from birth, but their gender can.
In the past people tend to have very clear ideas about what was appropriate to each sex and anyone behaving differently was regarded as deviant.
Today we accept a lot more diversity and see gender as a continuum (i.e. scale) rather than two categories: men are free to show their “feminine side” and women are free to show their “masculine traits”.
The biological approach suggests there is no distinction between sex & gender, thus biological sex creates gendered behaviour. Gender is determined by two biological factors: hormones and chromosomes.
Hormones
Hormones are chemical substances secreted by glands throughout the body and carried in the bloodstream. The same sex hormones occur in both men and women, but differ in amounts and in the effect that they have upon different parts of the body.
Testosterone is a sex hormone, which is more present in males than females, and affects development and behaviour both before and after birth.
Testosterone, when released in the womb, causes the development of male sex organs (at 7 weeks) and acts upon the hypothalamus which results in the masculinization of the brain.
Testosterone can cause typically male behaviours such as aggression, competitiveness,Visuo-spatial abilities, higher sexual drive etc. An area of the hypothalamus at the base of the brain called the sexually dimorphic nucleus is much larger in male than in females.
At the same time testosterone acts on the developing brain. The brain is divided into two hemispheres, left and right. In all humans the left side of the brain is more specialised for language skills and the right for non-verbal and spatial skills.
Shaywitz et al (1995) used MRI scans to examine brain whilst men and women carried out language tasks and found that women used both hemispheres, while men use the left only.
It appears that in male brains, hemispheres work more independently than in females, and testosterone influences this lateralization.
Chromosomes
The normal human body contains 23 pairs of chromosomes. A chromosome is a long thin structure containing thousands of genes, which are biochemical units of heredity and govern the development of every human being.
Each pair of chromosomes controls different aspects of development, and biological sex is determined by the 23rd chromosome pair. Chromosomes physically resemble the letters X and Y.
Males = XY
Females = XX
23 Pairs of Chromosomes of the human body
SRY Gene (Sex-determining Region Y gene)
At about 6 weeks, the SRY gene on the Y chromosome causes the gonads (sex organs) of the embryo to develop as testes.
Embryo
If the embryo has no Y chromosome, it will not have the SRY gene, without the SRY gene, the gonads will develop as ovaries.
Sometimes the SRY gene is missing from the Y chromosome, or doesn't activate. The foetus grows, is born, and lives as a little girl, and later as a woman, but her chromosomes are XY. Such people are, usually, clearly women to themselves and everyone else.
Koopman et al. (1991) found that mice that were genetically female developed into male mice if the SRY gene was implanted.
One of the most controversial uses of this discovery was as a means for gender verification at the Olympic Games, under a system implemented by the International Olympic Committee in 1992. Athletes with a SRY gene were not permitted to participate as females.