the role of chromosomes and hormones

• ao1: role of chromosomes

  • Chromosomes are made from DNA - genes are short sections of DNA. Humans have 23 pairs of chromosomes- 23rd pair determines biological sex.
  • Female sex chromosomes are XX and male are XY
  • A baby's sex is determined by whether the sperm that fertilises the egg is an X or a Y chromosome.
  • The Y chromosome carries a gene called the sex- determining region Y (SRY). This causes androgens to be produced in a male embryo.
• ao1: role of hormones

  • gender development governed by hormones
  • Prenatally hormones act upon brain development and cause development of the reproductive organs.
  • At puberty a burst of hormonal activity triggers secondary sexual characteristics such as pubic hair.
  • Males and females produce the same hormones but in different concentrations
• ao1: role of hormones- testosterone

  • Testosterone controls the development of male sex organs before birth. If a genetic male produces no testosterone, then no male sex organs appear. If a genetic female produces high levels of testosterone then male sex organs may appear.
  • High levels of testosterone are linked to aggression because such behaviour is adaptive for males, e.g. for competing with other males to mate with a fertile female and also for hunting (while females tend children).
• ao1: role of chromosomes- oestrogen

  • Oestrogen controls female sexual characteristics including menstruation.
  • During the menstrual cycle some women experience heightened emotionality and irritability - premenstrual tension or premenstrual syndrome (a diagnosable disorder).
  • In extreme cases PMS has been used (controversially) as a defence for violent behaviour in women
• ao1: role of hormones - oxytocin

  • Women typically produce oxytocin in larger amounts than men.
  • Stimulates lactation post-birth.
  • Reduces the stress hormone cortisol.
  • Facilitates bonding.
  • May explain why females are more interested in intimacy in relationships than men - though amounts are the same in men and women when kissing and during sex.
• ao3:One strength is evidence supports the role of testosterone.

  • Wang et al. (2000) ove 227 hypogonadal ben (men with low vels of testosterone) stosterone therapy for Bo days
  • Testosterone replacement improved sexual function, libido and mood, and significantly increased muscle strength in the sample.
  • This study suggests that testosterone exerts a powerful and direct influence on male sexual and physical behaviour even in adult males
• ao3: counterpoint to strength

  • In another study increasing testosterone levels in healthy young men did not significantly increase either interactional (frequency of sexual intercourse) or non-interactional (libido) components of sexual behaviour (O'Connor et al. 2004)
  • This suggests that, in 'normal' adults, additional testosterone has no effects on sexual or aggressive behaviour - though this doesn't challenge the role of testosterone in early development.
• ao3: One limitation is that biological accounts ignore social factors.

  • Hofstede et al. (2010) claim that gender roles are more about social factors than biology
  • Countries that value competition and independence above community (individualist cultures), e.g. US and UK, are more masculine, and masculine traits more valued than in collectivist cultures.
  • This challenges biological explanations of gender behaviour and suggests social factors may ultimately be more important in shaping gender behaviour and attitudes.
• ao3: Another limitation is that biological explanations are reductionist.

  • Accounts that reduce gender to the level of chromosomes and hormones exclude alternative explanations.
  • Cognitive explanations include the influence of, for example, schema. Psychodynamic explanations include the importance of childhood experiences.
  • This suggests that gender is more complex than its biological influences alone.