Role of chromosomes and hormones

• What are chromosomes made from?

  DNA
• What are genes?

  Short sections of DNA that determine the characteristics of living things.
• What are androgens?

  Male sex hormones
• What do androgens cause?

  Cause the embryo to become a male, without them, the embryo develops into a female.
• Biological approach to gender

  • The approach says that any differences between the 2 sexes are purely as a result of anatomical chromosomal and hormonal factors in the body.
• How is the baby’s sex determined?

  The baby’s sex is determined by the sperm that fertilises the eggs cell.

  • The baby will be a female if the fertilising sperm carries an X chromosome and the baby will be a male if the fertilising sperm carries a Y chromosome.
• How is a male produced?

  • The Y chromosome carries a gene called the SRY gene (sex-determining region).
  • SRY gene causes testes to develop in an XY embryo.
  • These produce androgens (male sex hormones)
  • These hormones cause the embryo to become a male, without them an embryo develops into a female.
• Hormones

  A chemical substance that circulates in the blood but only affects target organs.

  They are produced in large quantities but disappear quickly.
• What do hormones act on?

  Act on the development of the brain and reproductive organs.

  • The burst of hormones during puberty triggers the development of secondary sexual characteristics such as bodily hair.
• Is testosterone present in males and females

  Yes
• What does testosterone control?

  • Controls the development of male sex organs during foetal development.
  • Linked to aggression because it is adaptive, as it allows males to compete for the opportunity to mate with a fertile female.
• Research support for aggression and testosterone?

  Nanne Van De Poll

  • Found that female rates injected with testosterone became more physically and sexually aggressive.
• What does oestrogen control?

  Determines female sexual characteristics and menstruation.
• What does oestrogen cause?

  • Causes some women to experience heightened irritability during their menstrual cycle.
  • Known as premenstrual tension (PMT) or premenstrual syndrome (PMS).
  • PMS has been used as defence in cases of shoplifting and murder.
• What sex produces higher amounts of oxytocin?

  Women
• What causes women to produce high amounts of oxytocin?

  Giving birth
• How is oxytocin beneficial?

  • Oxytocin stimulate lactation, making it possible for mothers to breastfeed their children.
  • Reduces stress hormones like cortisol and facilitates bonding therefore known as ‘love hormone’
• What stereotypes have been generated due to men producing less oxytocin?

  As men produce less oxytocin this has fuelled the stereotype that men are less interested in intimacy and closeness.
• When is oxytocin produced other than childbirth?

  Kissing and sexual intercourse
• CAH

  Congenital Adrenal hyperplasia
• What is congenital adrenal hyperplasia?

  • A rare genetic disorder that causes high prenatal level of male hormones such as testosterone.
  • Can affect males or females.
  • More obvious in newborn baby girls who have ambiguous genitals due to masculinising effect of the male hormones.
• Research support for congenital adrenal hyperplasia?

  Berenbaum and Bailey, found females with CAH are often described by their family and friends as tomboys, exhibit high levels of aggression than other girls and show a preference for male toys.
• Evidence for testosterone

  • Male hypogonadism is a condition caused by a man’s testes failing to produce normal levels of testosterone. Wang et al, gave 226 hypogonadal men testosterone therapy for 180 days. Changes in body shape, muscle strength, sexual function were monitored.
  • Researchers found that testosterone replacement improved sexual function, libido and mood and saw increases in muscle strength in the sample.
  • Study shows testosterone exerts a direct influence on male sexual arousal and physical development.
• Why is ignoring social factors a limitation?

  • Hofstede et al claimed that gender roles around the world are due to social norms rather than biology.
  • Countries which place individual competition and independence above the needs of the community are more masculine in their outlook. Consequently, traditional masculine traits will be more highly valued within these societies.
  • This suggests social factors may be more important in shaping gender behaviour and attitudes.
• How is the explanation reductionist?

  • Explanations which reduce gender to the level of chromosomes and hormones have been accused of ignoring or underplaying alternative explanations.
  • Other explanations e.g cognitive explanations draw attention to the influence of thought processes such as schemas. Alternatively the psychodynamic approach points to the importance of childhood experiences such as interaction within the family.
  • This suggests that gender is more complex than its biological influences alone.
• How does the approach pathologise gender?

  • For example, there are various conditions caused by changes in sex hormones such as premenstrual syndrome which arises due to fluctuating hormone levels during a women’s menstrual cycle. PMS has an impact on female emotional state as well as physical symptoms like headaches and fatigue.
  • females can access treatment to control mood swings and physical symptoms. Rodin, object to the medical category of PMS as it stereotypes female experience and emotion. They claim PMS is a social construction, not a biological fact.
  • Encourages damaging stereotypes
• David Reimer- Case study

  • Twin boys Bruce and Brian. Following a botched circumcision operation at 6 months of age, one of the twins, Bruce was left without a penis.
  • ‘Brenda’ had never adjusted to life as a girl and was experiencing severe psychological and emotional problems.
  • When she was told the truth about her childhood by her parents she immediately went back to living as a man.
  • He committed suicide in 2004.
• How does the case of David Reiner support the biological explanation of gender development?

  • The final outcome of David transitioning to a man suggests that biological influences are more important than socialisation.
  • He will always be biologically male with the male XY chromosome patterns and his brain would have received normal levels of testosterone during foetal development.
  • Treating him as a girl for many years appeared not to have affected his identity as a man or he would of stayed in his assigned role as a women.