role of chromosomes and hormones

• chromosomes

  • 46 chromosomes arranged into 23 pairs - 23rd pair determines biological sex
• • females - XX
  • males - XY
• • all eggs have an X chromosome
  • sperm either carry X or Y which determines the gender
• • Y chromosome carries gene called the 'sex determining region Y' (SRY)
  • SRY gene causes testes to develop
  • the testes produce androgens: male sex hormones
  • androgens cause embryo to become male
• Hormones

  • influence gender development
  • in womb hormones act on brain development and cause development of reproductive organs
  • during puberty they trigger secondary sexual characteristics like pubic hair
  • males and females generally produce same but in different concentrations
• testosterone

  • controls development of male sex organs
  • link to aggression
  • Nanne Van de Poll showed female rats injected with testosterone became more physically and sexually aggressive
• oestrogen

  • determines female sexual characteristics and menstruation
  • causes some women to experience heightened emotionality and irritability during menstrual cycle - PMS
• oxytocin

  • women typically produce larger amounts, particularly as a result of giving birth
  • stimulates lactation
  • reduces stress hormone cortisol and facilitates bonding
  • released in massive quantities during and after birth to make mothers feel 'in love'
  • fuels stereotype that men are less interested in intimacy - however - shown that both sexes produce roughly equal amounts during activities like kissing
• S - supporting evidence

  • Dabbs found that offenders with the highest levels of testosterone were more likely to have committed violent or sexually motivated crimes
  • Van Goozen found that trans women showed decrease in aggression whilst trans men showed an increase
  • suggests that sex hormones exert influence on gender-related behaviours
• W - contradictory evidence

  • Tricker conducted double-blind study - 43 males given weekly injection of either testosterone or placebo - there was no significant difference in aggression found after 10-week period
  • shows sex hormones have no consistent effect on gender-related behaviour
  • the studies also use small samples of unusual people, limiting extent to which meaningful generalisations can be made
• W - overemphasis on nature

  • if gender identity is purely down to biology there should be more differences in male and female behaviour than there are
  • major review of research found significantly more differences within the sexes than between
  • the social learning may explain better cultural differences as it acknowledges social context
• W - reductionist

  • reduces gender to chromosomes and hormones, ignoring alternative explanations
  • oversimplifies a complex concept as behaviour is more likely due to a combination of nature and nurture, making an interactionist approach potentially more appropriate in explaining gendered-behaviour