Biological Content
| For this section you need to be able to:
a Briefly describe the role of the central nervous system and neurotransmitters in human behaviour. b Briefly describe the role of genes in behaviour (including the nature/nurture debate). c With regard to gender development, describe the role of genes, hormones, and brain lateralisation. d Evaluate the influence of biological factors on gender development including comparison with explanations from the Psychodynamic and Learning Approaches. Include the issues of use of animals and methodology in drawing conclusions. |
According to the biological approach our gender (feelings of masculinity or femininity) is a direct consequence of our biological makeup. This is determined at conception. Gender therefore is a product of nature. This is due to evolutionary pressures through which males adapted to have a specific set of abilities that enabled survival whereas females have other, different skills. These abilities are passed on via genetic inheritance.
Chromosomes determine gender and sex development. Sperm contains either an X or a Y chromosome. Only one sperm bonds with the ovum. The ovum contains an X chromosome. If the sperm is Y then the embryo will be chromosomally male with an XY chromosome. If the sperm is X it will be XX— female.
The chromosome make up influences the secretion of hormones. XY leads to the release of androgens (male hormones). This causes the sex organs to develop as male. In the absence of these hormones the embryo develops as female.
This hormonal mix influences the development of the embryonic brain and may lead to brain lateralisation. Male brains are more lateralised with specific functions being allocated to each hemisphere e.g. spatial skills in the right and language skills in the left. Functional differences may result from this including increased ability to manipulate objects in space. In evolutionary terms this would make males better hunters.
Female brains are less lateralised; their brains have a thicker connective band (corpus callosum) between the hemispheres. This means they use both sides for language and therefore have better communication skills. In evolutionary terms this would make females better at socialising and therefore binding social groups together.
Evaluation of the biological explanation of gender
Understanding the role of hormones and chromosomes in the development of gender can be useful in helping those born with atypical profiles. Research suggests that one person in every 500 is born with genitals that do not match their sex chromosomes or which are not obviously male or female (intersex). This means that they can be assigned a gender at birth that is not valid for them. Knowledge from this approach allows us to assist the developmental pathway for such children to enable them to adopt the most suitable gender role for them.
This approach can also help explain cases of gender identity disorder (GID) where the person feel they are one sex (gender) but are trapped in the body of the other sex.
The biological approach is very scientific and as such is widely regarded as providing a credible explanation because it provides material evidence in support of its claims, for example it is possible to measure hormone levels and monitor changes in brain structure through post mortem studies or brain scanning techniques
This explanation is challenged by the Learning Approach which states that gender development occurs through the process of observing others and imitating gender appropriate behaviour from role models such as parents, and has very little to do with our biological sex. This is the NURTURE side of the debate and there is little doubt that how we are socialised has an impact on our gender role.
The case of David Reimer supports the biological approach as he always felt more male then female. This suggests that even when someone is brought up and reinforced for behaviour appropriate to a gender their biological sex seems to have more of an effect on how they feel about their gender identity.
The case of Daphne Went refutes the biological approach because she is chromosomally male, but lives successfully as a female despite this. Her case suggests that socialisation (nurture) is more important than genes or chromosomes in gender role.
Evidence from cases of androgen insensitivity syndrome and androgenital syndrome suggest that genetic sex can be overridden by hormone exposure during pre-natal development. In these cases, children with one biological gender are immune to, or not exposed to, the correct hormones during their pre-natal development . Case studies of such children show that they develop behavioural characteristics consistent with the other gender. This supports the biological view as it shows that hormones, a biological factor, are linked to gendered behaviour.
Case study evidence is subject to criticisms of population validity. Such cases as those described above are rare and it may be that the individuals concerned are unusual people who are not representative of the rest of us, for instance David Reimer was an identical twin who may have been more influenced by his twin brother than children who do not have a twin.
Pfeiffer (1936) found that transplanting male gonads onto female rats caused the release of male sex hormones in these females. Other studies provided male rats with female hormones during development. The treated rats showed reversed sexual behaviour (Young, 1964). Further investigation showed that changes had occurred in a part of the brain called the sexually dimorphic nucleus of the pre-optic area. Hormones therefore affect brain structure and brain structure affects behaviour.
However, Research on animals may not be applicable to humans as humans are much more complex than rats, for example. This means that animal studies may not give us a true picture of gender development in humans where changes at puberty or with aging interact with the environment of the person to create gendered behaviour.