The Role Of Chromosomes And Hormones In Sex And Gender Flashcards
What are chromosomes?
Found in the nucleus of living cells and carry information in the form of genes
How is biological sex determined?
- at conception by chromosomes
- the 23rd pair of chromosomes contain the instructions for a zygote’s sex (determines biological sex)
- XX - female
- XY - male
Describe the role of chromosomes
- zygotes develop into embryos that have the exact same genitalia for the first 8 weeks of development
- the Y chromosomes in males carry the SRY gene (sex-determining region Y)
- this gene instructs the testes to develop
- at 8 weeks, the testes produce androgens (male hormones) that stimulate the development of remaining male genitalia
- genetic females do not produce these androgens, so female genitalia develops instead
Define hormones
A biochemical substance that circulates in the blood but only affects target organs
How are hormones produced?
In large quantities
But disappear very quickly
Regardless, they are very powerful
Describe the role of hormones
- during pre-natal development, hormones affect brain development and cause reproductive organs to develop
- they also cause the development of secondary sexual characteristics at puberty
Do males and females produce the same hormones?
Yes, but at different concentrations
What are the three most relevant hormones in sexual development?
Testosterone
Oestrogen
Oxytocin
Define testosterone
A hormone from the androgen group that is produced mainly in the male testes (& in smaller amounts in the female ovaries)
Associated with aggressiveness
What is testosterone associated with and elaborate
Aggression
This is suggested to be an evolutionary adaptation
- aggressive males are better adapted to compete for mates and win, as well as protect their young from other predators and successfully hunt for prey
Define oestrogen
The primary female hormone that regulates the menstrual cycle and reproductive system
Describe the function of oestrogen and its affects on the human body
- determines female sexual characteristics (prenatally and during puberty) and menstruation
- this hormone can cause feelings of irritability and heightened emotionality during the menstrual cycle (AKA Premenstrual Tension/PMS)
- although PMS has been disputed as a medical disorder, it has been successfully used in courts to defend shoplifting and murder
Define oxytocin
A hormone which causes contraction of the uterus during labour and stimulates lactation
Describe the quantities in which oxytocin is produced
Much higher quantities in females than males - mainly due to childbirth
Why is oxytocin produced in large quantities during labour and after childbirth?
- help the mother ‘love’ the baby and bond with it
- lactate (breastfeed)
- reduce stress (cortisol levels)
What stereotypes has oxytocin led to?
Men being less interested in intimacy and closeness, despite makes and females producing roughly equal amounts of oxytocin during activities like kissing and sexual intercourse
Outline the case of David Reimer
- Bruce and Brian Reimer were twins born in 1965, and after a botched circumcision at 6 months of age, Bruce was left without a penis
- the parents called Dr John Money, a psychologist developing a theory on gender neutrality (He theorised that biological sex was less important than nurture in establishing gender identity, and encouraged Bruce’s parents to raise him as a girl)
- he was raised in a stereotypically feminine way and was never told about his gender reassignment (he became Brenda)
Outline the findings of the David Reimer case
- Brenda was monitored by Dr Money into their teens and their success was used to support his theory
- However, in reality, Brenda never properly adjusted to life as a female and experienced many psychological and emotional problems
- Brenda was eventually told the truth about their biological sex and immediately identified as a man (called David)
- Unfortunately David committed suicide at age 39
What can we learn from the David Reimer case?
- evidence for the biological approach in gender development
- supports the role of biology in gender identity as David continued to identify as a male (biological sex) despite the fact that he was raised femininely and without male genitalia
A03: research support? Outline Wang’s study
- evidence supports the role of sex hormones in gender development even in mature males
- Wang et al. (2000) studied 227 men with hypogonadism (a condition where makes fail to produce normal levels of testosterone in the testes)
- she gave them testosterone replacement therapy for 180 days and observed significant improvements to their sexual functioning (including libido), muscle strength and body shape
A03: research support? What can be concluded from Wang’s study?
Testosterone exerts a powerful and direct influence on male sexual arousal, as well as physical development, in adulthood
A03: research support? Contradictory research?
- O’Connor et al. (2004) increased testosterone in a sample of healthy makes and observed no significant differences in sexual behaviour (interaction or drive)
- there were no differences in aggression or anger either
- this study was also double-blind with a placebo condition (avoids bias)
-conclusion: in ‘normal’ adults, additional testosterone has no effects on their sexual or aggressive behaviour - though this does not challenge the role of testosterone in early development
A03: social factors ignored. How is this a limitation?
- one limitation of biological accounts is that they ignore the role of social factors in gender-related behaviour
A03: social factors ignored. Outline Geert Hofstede et al. (2010) theory
- Claim that gender roles around the world are a consequence of social norms more than biology
- These researchers suggest individualist countries are more masculine in their outlook. Consequently, traditional masculine traits will be more highly valued within these societies
