the role of chromosomes and hormones

• chromosomes are made from DNA and humans have 23 pairs of chromosomes. The 23rd pair determines biological sex. Under a microscope those chromosomes are either X or Y shape. 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 Y
• the Y chromosome carries a gene that carries a gene called the sex determining region (SRY). This causes androgens to be produced in a male embryo
• 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
• 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 than male sex organs may appear. High levels of testosterone are linked to aggression because such behaviour is adaptive for males like competing with other males to mate with a fertile female
• oestrogen controls female sexual characteristics including menstruation. During the menstruation cycle some women experience heightened emotionality and irritability. This is premenstural tension or premenstural syndrome which is a diagnosable disorder. In extreme cases, PMS has been used controversially as a defence for violent behaviour in women
• women typically produce oxytocin in larger amount than men. Oxytocin stimulates lactation post birth, reduces the stress hormone cortisol and it facilitates bonding
• One strength is evidence supports the role of testosterone. Researchers gave 227 hypogonadal men (men with low levels of testosterone) testosterone therapy for 180 days. Testosterone replacement improved sexual function, libido and mood significantly increases 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
• One limitation is that biological accounts ignore social factors. Researchers claim that gender roles are more about social factors than biology. Countries that value competition and independence about community (individualist cultures) like US and UK are more masculine and masculine traits more valued than collectivist cultures. This challenges biological explanations of gender behaviour and suggests social factors may be more important in shaping gender behaviour and attitudes
• One limitation is that biological explanations are reductionist. Accounts that reduce gender to the level if chromosomes and hormones exclude alternative explanations. Cognitive explanations include the influence of schema. Psychodynamic explanations include the importance of childhood experiences. This suggests that gender is more complex than its biological influences alone