chromosomes and hormones

• the role chromosomes

  • chromosomes are made from DNA
  • chromosomes carry genetic info (genotype) and physical / behavioural info (phenotype)
  • we have 23 pairs of chromosomes
  • the 23 rd pair determines our biological sex
  • eggs = X chromosome
  • sperm = X / Y chromosome
• how the embryo becomes male

  • in the first few weeks there are no structural differences between a male and female embryo
  • the Y chromosome in males, carry a gene called the sex determining region (SRY)
  • the SRY gene causes testes to develop in an XY embryo
  • testes produce androgens these make the embryo male
  • if androgens aren't produced then the embryo will be female
• chromosome role in gender

  genetic difference between biologically male and female chromosomes result in:

  • observable behavioural characteristics
  • this occurs due to the differences in coding for neural structures and hormone level which influence gender exxpression
• the role of hormones

  • chromosomes determine biological sex but hormones influence gender
  • womb - hormones act on the development of our brains and cause the reproductive organs to develop
  • puberty - the burst of hormonal activity causes out secondary sexual characteristics to develop
  • male and females produce many of the same hormones but different amounts
• hormones

  chemical messengers released by the glands into the bloodstream to act on a target organ
• testosterone

  • male hormone controlling the development of male sex organs
  • links to aggression
  • female rats who had been injected with testosterone were moe sexually and physically aggressive
• oestrogen

  • female hormone controlling female sexual characteristics including menstruation
  • causes women to be highly emotional and irritable during their cycle
• oxytocin

  • known as the love hormone
  • makes women lactate
  • reduce cortisol ( stress hormone)
• oversimplifies a complex concept

  • reduce gender to level of chromosomes and hormones, and ignores the alternative to explaining gender development
  • the cognitive approach would draw attention to the thought processes that underpin gender development
  • even though these processes arise via maturation it is still not stated by the biological approach
• outline the evidence supporting chromosomes and hormones

  • research shows in prisons, the offenders with the highest level of testosterone were more likely to have committed violent or sexually motivated crime
  • demonstrates how testosterone is linked high levels of aggression both physically and sexually , thus supporting the research conducted on female rats
  • studies into transgender individuals showed transgender women had a decrease in their levels of aggression and visuo spatial skills and transgender men showed to opposite
• contradictory evidence

  • in a double blind study 43 males were given either a weekly injection of testosterone or a placebo
  • no significant differences in aggression were found in either groups
  • another studies also showed that sex hormones had not consistent effect on gender related behaviours
  • many studies into the effect of hormones on our behaviour are often conducted on animals
  • this limits the extent to which generalisations can be made