Role of Chromosomes & Hormones

• Chromosomes

  Found in nucleus of cells; made from DNA, 23 pairs – 23rd pair determines biological sex
• Genes

  DNA determining characteristics of a living thing
• Female

  XX – fertilising sperm carries X chromosome
• Male

  XY – fertilising sperm carries Y chromosome; Y carries sex-determining region SRY
• SRY

  Causes testes develop in XY embryo then make androgen that make embryo a male – w/o it then embryo is female
• Androgen

  Male sex hormone
• Hormones

  Chemical substance control and regulates cell/organ activity; in womb – act on brain development, cause development of reproductive organs
• Puberty

  Triggers secondary sexual characteristic development eg pubic hair
• Testosterone

  Male hormone controls development of male sex organs; from androgen, associated with aggression
• Testosterone is produced at 8 week foetal development
• Testosterone research

  • Nanne Van de Poll 1988 = female rats sexually + physically aggressive after injected w/ testosterone
• Oestrogen

  Female hormone determines female sexual characteristics and menstruation; causes PMS
• PMS/T

  Pre-menstrual syndrome or tension – heightened emotionality and irritability; defence for murder and shoplifting
• Oxytocin

  Causes contraction of uterus during labour and stimulates lactation; reduces cortisol (stress hormone), facilitates bonding, aka love hormone, make new moms in love with baby as mass amount released
• Men have less oxytocin thus stereotype: men less interested in intimacy and closeness – EVIDENCE for otherwise = both sexes have same amount in amorous activities eg kissing and sex
• Support - role of chromosomes and hormones

  • Dabbs (1995) – prisoner offenders w/ higher testosterone levels likely be convicts of violent and sexually-motivated crimes
  • Van Goozen (1995) = transwomen decreased aggression and visuospatial skills but transmen show opposite - testosterone causes increases aggression
  • more testosterone in men than women thus men more likely show aggression therefore sex hormones influence gender-related behaviour
• Limitation - hormones don't determine behaviour

  • Tricker 1996 = double blind procedure, 43 males injected w/ testosterone or placebo and was no difference in aggression
  • Slabbekoorn 1999 = sex hormones had no consistent effect on behaviour
  • testosterone didn't affect aggression level therefore undermines influence of hormones on gender-related behaviour
• Limitation - PMS as medical category overexaggerates hormone impact


  
  

  • Rodin (1992) = PMS is social construct not fact, privileges men over women in legal instances, feminists accuse this medicalisation of women's emotions biologically
  • stereotypes female emotion and experience therefore controversial and legal implications – alleviating accountability of women's crimes
• Limitation - Overemphasis on nature

  
  

  • Maccoby & Jacklin 1974 = significant differences in behaviour within the sexes rather than between
  • SLT
  • would expect more differences between sexes if gender identity due to biology [nature], social context is important as social norms explain cultural differences in gender-roles [eg; Western = male and female becoming more androgynous in behaviour] therefore SLT suggest not sole focus on biology