The Role of Chromosomes and Hormones
Paper 3 Issues and Options in Psychology
The role of chromosomes
- Chromosomes are made from DNA, there are 46 chromosomes in the human body arranges into 23 pairs. The 23rd pair determines biological sex.
- The chromosomal structure for each gender is as follows:
Males = XY
All normal egg cells produced by a human ovary have an X chromosome, half the sperm carry an X chromosome and half a Y. A baby’s sex is determined by the sperm that fertilises the egg.
The Y chromosome carries a gene called SRY, this causes testes to develop. The testes produce androgens (male sex hormones) which cause the embryo to become a male, without them it develops into a female.
The role of hormones
Chromosomes initially determine a person’s sex but most gender development actually comes about through the influence of hormones. In the womb, hormones act upon brain development and cause the development of reproductive organs. At puberty, a burst of hormonal activity triggers the development of secondary sexual characteristics.
You need to know about the role of 3 different hormones; testosterone, oestrogen and oxytocin.
Testosterone
• A predominantly male hormone (women also produce it, but at about 10% of the level found in males)
• Controls the development of male sex organs
• Begins to be produced at around week 8 of gestation
• Associated with the masculinisation of the brain, such as the development of specific areas like spatial skills, competativeness and aggressiveness.
AO3 Testosterone – evaluation
Point:
There is evidence of a link between testosterone levels and male-typical behaviours
Evidence: For example, Deady et al (2006) measured testosterone levels and gave the BSRI to women aged between 23 and 30, asking additional questions about maternal personality (e.g. the importance of having children, career, ambition). It was found that testosterone levels negatively correlated with low measures of maternal personality and reproductive ambition.
Elaboration: This is a strength because it demonstrates that testosterone levels have an impact on the development of typical male and female behaviours, indicating that testosterone has a key role in the development of gender development.
Point:
A limitation of Deady et al.’s study is that it is correlational. Evidence: While a negative correlation was found between testosterone levels and maternal personality, correlations cannot establish causation. This means it is unclear whether testosterone influences maternal attitudes or whether another factor explains the relationship. Elaboration: Consequently, the findings provide only limited support for a biological explanation of sex-role stereotypes.
Point:
Deady et al.’s research is socially sensitive because it investigates biological influences on gender-related behaviour. Evidence: Findings linking testosterone levels to maternal ambition could be misused to support deterministic views of gender and reinforce existing stereotypes about women’s roles in society. Elaboration: This raises ethical concerns about the potential social consequences of the research, meaning psychologists must be careful when interpreting and communicating the findings.
Oestrogen
- A primarily female hormone (small amounts are produced in males)
- Determines female sexual characteristics and menstruation
- Responsible for both physical and emotional changes experience by women during their menstrual cycle (e.g. PMS)
- Oestrogen plays a role in ‘feminising’ the brain, promoting neural interconnections for equal use of both hemispheres
Oestrogen – evaluation
Point:
There is evidence of oestrogen being necessary for female-only behaviours
Evidence: For example, Albrecht & Pepe (1997) found that increasing oestrogen levels in pregnant baboons led to heightened cortisol production, which assisted the development of organs and tissues in foetuses.
Elaboration: This is a strength because it demonstrates that oestrogen is necessary to pregnancy and for the growth of foetuses, a role that is exclusively fulfilled by women, indicating that oestrogen has a key role in gender/ sex related behaviours.
Point:
There are considerable objections to the idea of pre-menstrual syndrome (PMS) on the grounds that it stereotypes female experience.
Evidence: For example, feminist writers claim that PMS is a social construction, not a biological ‘fact’ but a way of privileging certain groups over others, in this case men over women.
Elaboration: This is a weakness because research into oestrogen and PMS appears to lead to the medicalisation of women’s lives (defined and treated as medical conditions) and ultimately the dismissal of women’s emotions, especially anger, by explaining them in biological terms.
Oxytocin
- A hormone that also acts as a neurotransmitter, produced in the brain by both males and females to control key aspects of the reproductive system
- Women produce much larger amounts of oxytocin than men, particularly as a result of giving birth, it stimulates lactation.
- Oxytocin reduces the stress hormone cortisol and facilitates bonding, it’s referred to as the ‘love hormone’
- Oxytocin is released in massive quantities during labour and makes new mothers feel ‘in love’ with their baby. This has fuelled the popular stereotype that men do not make ‘as good’ caregivers as women and are less interested in intimacy and closeness within a relationship.
Oxytocin – evaluation
Point:There is evidence to suggest that there is a relationship between oxytocin and maternal behaviour.
Evidence: For example, Van Leengoed et al (1987) injected an antagonist of oxytocin into female rats shortly after birth to inhibit oxytocin production. Mothers treated in this way showed a delay in maternal behaviours, such as picking up and grooming their pups. Normal maternal behaviour was seen when the antagonist wore off.
Elaboration: This is a strength because the findings support the idea that oxytocin is involved in the promotion of maternal behaviour, supporting the link between the hormone oxytocin and gender development.
Point:
Much of the research into the role of hormones in sex and gender can be criticised for extrapolation.
Evidence: For example, most of the research only investigates the influence of hormones on sex and gender in animals, therefore little is being discovered about how hormones impact sex and gender in humans.
Elaboration: This is a weakness because the results of any animal research cannot be generalised beyond the experiment to humans because of differences in brain functioning and physiological development, this renders most of the research in this area as useless, which raises the question as to whether animal research should be conducted if it offers so little information as to human development.