ROLE OF CHROMOSOMES + HORMONES

• TESTOSTERONE 


  is a steroid hormone, which is produced prenatally + affects the development of the generation + also acts upon the brain development. Some XY individuals have an insensitivity to testosterone, so that no external genitalia develop
• PRENATAL (testosterone)

  • the gonads (sex glands, testes in males + ovaries in females) are originally identical in both XX+XY i.e both male + female embryos have external genitalia that looks feminine
  • around 3 months, if the fetus is to develop as a male, the SRY (sex determining region Y) causes the gonads to become testes + they produce androgens (male hormones) e.g testosterone which causes external male genitalia to develop. if they do not become testes, they become ovaries
• POSTNATAL (testosterone)

  • First 6 months = testosterone acts on the hypothalamus (sexual dimorphic nucleus - bigger in males). Without this, the brain develops as a female type, rather than being associated with spatial, competitiveness + aggressiveness - LINK TO GENDER DYSPHORIA
  • puberty = secondary sexual characteristics, such as facial hair, deepening voice + aggression
• OESTROGEN

  is a steroid hormone which promotes the development + maintenance e.g physical change (such as breast development) + directing the menstrual cycle (increasing blood supply the uterus during pregnancy), as well as causing psychological + emotional effects, e.g heightened emotions (PMS), lapses in self-control + anti-social behaviour
• OESTROGEN

  • Females do not need hormones to direct prenatal genital development
  • oestrogen plays a role in feminising the brain, promoting neural interconnections for equal use of cooperation
  • diminishing oestrogen levels is associated with the onset of menopause in women
• OXYTOCIN - the 'love' hormone

  is a polypeptide hormone + it is produced by the pituitary gland + evoke feelings of contentment + calm. It also has healing properties with wounds
• OXYTOCIN

  produced by men + women, although it's action is greater in females as it is synergised (combines) with oestrogen to enhance each others effect. This hormone stimulates contractions during childbirth + also lactation (the 'let down' reflex), it reduces the stress hormone cortisol (reduced FOFR), triggers tend + befriend (in females) + facilities bonding, nurturing 'nesting' behaviour, acceptance + protection
• OXYTOCIN 


  • males - small amount of oxytocin = less interested in intimacy + closeness on a relationship
  • Both sexes produce oxytocin in equal amounts during amorous activities such as kissing + sexual intercourse / orgasm (increases five-fold)
• (+) SUPPORTING evidence for the role of CHROMOSOMES

  research into intersex individuals - MONEY + EHRHARDT (1972) = may have been wrong in claiming that biological sex was not the main factor in gender development.

  = sex of rearing was much more important + recommended that intersexual individuals such as DAVID REIMER could be successfully raised as either a boy or girl = raised as a girl (nature) but still had male characteristics (nurture).

  This suggests that (biological determinism/factors etc.)... in the development of gender develop.
• (-) WEAKNESS for the role of CHROMOSOMES

  + biological basis is that ignores the role of nurture, cultural + social influences.

  = SLT shows the importance of social context in the learning of our gender identity. The role of culture is also explained by the case of the BARTISTA FAMILY (IMPERITO MCGINLEY ET AL 1974)
• IMPERITO MCGINLEY ET AL 1974

  • 4 children = born with (F) genitalia = raised as girls
  • testosterone produced during puberty = production of male genitalia - genetically XY = external male genitalia = testosterone insensitivity
  • girls accepted their new male role

  This challenges biological explanations of behaviour + suggests social factors may ultimately be more important in shaping gender behaviour + attitudes.
• (+) SUPPORTING evidence for the role of TESTOSTERONE

  HUMAN EVIDENCE - WAND ET AL (2000)

  gave 227 hypogonadal men (condition where testes fail to produce normal less of the male sex hormone) testosterone therapy for 180 days. They found an improved sexual function, libido, mood + muscle strength
• (+) SUPPORTING evidence for the role of OESTROGEN

  FITCH + DENENBERG (1998) = ANIMAL STUDY -

  found that suppressing production of oestrogen by removing ovaries 
from female rats as late as 16 days after birth led to an increased corpus callosum brain area.

  • findings = later sensitive period for oestrogen regulated feminisation of the brain compared with testosterone - regulated masculinisation
• (+) SUPPORTING evidence for the role of OXYTOCIN

  REAL WORLD APPLICATION -

  the administration of oxytocin during childbirth reduces haemorrhaging decreased mortality rates in both mothers + infants 

• (-) WEAKNESS for the role of HORMONES

  CONTRADICTORY FOR TESTOSTERONE - TRACKER ET AL (1996)

  found no differences in aggression after 43 males were given weekly injections of testosterone or placebo
• (-) WEAKNESS for the role of HORMONES

  REDUCTIONISM VS HOLISM

  It is too simplistic and it oversimplifies a complex concept.  Reducing gender to a level of chromosomes and hormones therefore ignore or underplay alternative explanations….

  E.G

  • The cognitive approach - the changing thought process and maturation of the developing brain, such as schemas (GST). 
  • The psychodynamic approach would point to the importance of childhood experiences such as interaction within the family.
• ROLE OF CHROMOSOMES 


  • made from DNA - genes are short sections of DNA
  • 23 pairs - 23rd determines sex
  • female = xx (microscope)
  • male = xy (microscope)
• ROLE OF CHROMOSOMES 


  Babys sex is determined by whether the sperm that fertilises the egg is an x or y chromosome
• ROLE OF CHROMOSOME


  Y chromosome has SRY gene =

  sex determining region Y (SRY). This causes androgens to be produced in a male embryo.
• (-) ROLE OF CHROM/HORM

  The reductionist vs holistic view says that it is too simplistic and it oversimplifies a complex concept. Reducing gender to a level of chromosomes and hormones therefore ignores or underplay alternative explanations for example, the psychodynamic approach which points to the importance of childhood experiences such as interaction within the family.