chromosomes + hormones Flashcards
Chromosomes AO1
Gender is caused by neurological differences brought on by chromosological differences and their effects on early and late testosterone exposure. Testosterone is a steroid hormone which stimulates the development of male secondary characteristics.
Early testosterone exposure
Males = XX
Femles = XY
Neonates are all essentially female but at between 4-8 weeks the SRI gene on the Y chromosome orders their gonads to release hormones. Females don’t release much but male gonads release testosterone which effects the development of the brain. These brain differences are thought to be the cause of gender differences.
One brain area affected by this early testosterone exposure is hypothalamus . studies show the sexually dimorphic nucles was bigger in men than women. The theory is that this then prompts different gender behavior.
Research related to neurological evidence
Swaab (85)– analysed 13 men and 18 women between 10 and 93 years and found differences in an area of the hypothalamus they called the sexually dimorphic nucleus. Males were 2.5 x larger with 2.2x the number of cells.
This supports neurological differences
However, there have been problems replicating this evidence.
Swaab (11) Looked at the BSTc for men and women. They found that both hetero sexual and homosexual men had a 2x larger BSTc but that women and MTF transsexuals had a smaller BSTC. (BSTc joins the hypothalamus and the amygdala) TS gender identity is biological as gender identities influenced by the shape and size of the BSTc
But none of these differences are found in children under seven –> neuro plasticity?
Suggest brain changes throughout life, although not in date could take a while to the BSTc to develop, maybe not prenatal testosterone exposure that causes this the external influences instead
Money case study on David Reimer
Identical twin, faulty circumcision which left him barely any penis. Money recommended to the parents they reassign him to be a girl. However the subject always had social problems and when the mother told and then they were girl their response was I was relieved and suddenly it all made sense. After this and got married
This shows biological factors away more influential on gender identity done the environmental upbringing
Oestrogen AO1
Females do not need hormones to direct prenatal genital development in the same way that males do; all fetuses start off female. However, there is some evidence to suggest that oestrogen might have prenatal effects, such as causing a smaller brain size (Shi et al., 2015). It is also suggested oestrogen plays a role in feminising the brain, promoting neural connections which leads to the equal use of both hemispheres and is also associated with sensitivity and corporation.
Research relating to oestrogen
Albrecht + Pepe increasing oestrogen levels in pregnant baboons led to heightened cortisol production , which assisted development or organs and tissues in fetuses and led to reduced miscarriages. Thus showing oestrogen is vital in prenatal development
but
Issues with generalisability to humans, however Okon et al. (1998) found Androgen levels (testosterone) are higher in women who have recurrent miscarriages than in normal fertile controls.
Feminist argument on the role of oestrogen
Role of oestrogen on a woman’s mood has been questioned and many objects and many object to PMS as a medical category on the grounds that it is stereotyped as a female emotion. RODIN claims PMS is a social construction and not a biological fact better way of privileging men over women
Oxytocin AO1
Females have higher levels of oxytocin than men, as oestrogen has been found to increase oxytocin secretion.
Some researchers have linked this oxytocin to increased sociability and the formation of bonds and attachments between people. Oxytocin is often called the ‘love’ hormone because it promotes feelings of bonding/attachment in both men and women.
produced in the pituitary gland and produces feelings of contentment and calmness.
released into the bloodstream during labour and also when the nipples are stimulated during breastfeeding. This helps the mother to bond with her baby and to produce milk.
At times of stress, oxytocin dampens the fight-or-flight response and triggers the ‘tend and befriend’ response in females to ensure that they look after their young and form protective alliances with other women.
Research related to oxytocin
Van Leengoed injected an antagonist of oxytocin into female rats shortly after birth which inhibits its production. Mothers treated in this way delayed maternal behaviours, such as picking up and grooming pups. When the effects of the drug wore off, normal maternal behavior was seen.
TS oxytocin has an effect on postnatal interaction and maternal behaviour
Insel (2001) found that administering Oxytocin to female prairie voles, a species known to be monogamous led to forming long-term mating partnerships, whilst similar administration of oxytocin to female montane voles, a species known to be promiscuous, produced no such effect.
TS oxytocin promotes pair bonding in monogamous species
Evaluation on hormones and chromosomes one gender
Scientific and repeatable measures which are objective
But oxytocin studies only look animals and Thus generalisability issues
Reductionist: sympathise complex idea of gender into a single component and ignores external factors such as SEX ROLE STEREOTYPES
Deterministic controlled by jeans and hormones which can’t be changed. Suggest child rearing and stereotypes aren’t important thus is an oversimplistic explanation for gender.
A typical sex chromosomes
I.e. Klinefelter’s syndrome and Turner’s syndrome
Inheriting too many or not enough copies of sex chromosomes leads to atypical chromosome patterns, which can cause serious developmental complications. For example, males with an additional X chromosome (XXY) develop Klinefelter’s syndrome, which is a condition characterised by tall stature and, often, impaired fertility and language deficits. Turner syndrome is another syndrome caused by an atypical chromosome pattern. Women with Turner syndrome have one X chromosome(X0), and are often very short, and do not undergo puberty. Some people with Turner syndrome also have kidney or heart problems.
Research related to a typical sex chromosomes
–> Klinefelter
DeLisi subjected 11 KS pts and 11 non-KS controls to a psychiatric interview, cognitive tests and MRI scan. 10 of KS males had some form of psychiatric disturbance and generally KS males had smaller frontal and temporal lobes which might explain the language deficits. TS there is a biological basis for language deficits and differences in behaviour
Implications: from Maguire study we understand that we can increase grey matter (NEUROPLASTICITY), and Therefore we can intervene and improve language deficits by increasing connections interbred
Simpson found that behavioural and language difficulties resulting from KS could be successfully treated with androgen therapy, such as testosterone supplements and psychological counseling with greater improvements the earlier the treatment was given. TS idea of the biological basis and suggest Klinefelter’s is due to a lack of testosterone, which implies it is treatable with the use of drugs.
Research related to a typical sex chromosomes
–> Turner syndrome
Quigley gave 123 with TS either oestrogen supplements or a placebo from ages 5-12. There were no differences in physical development between the 2 groups before 8.5 years but between 8.5 and 12 those given Oestrogen had earlier and greater breast development, although no other differences in puberty were noted. Issues in supplements are beneficial between 8 to 12, good psychosocial benefit normalising breast development
Brown et al. (2002) performed MRI of 26 girls with TS and 26 gender age matched non-TS girls, finding TS girls had smaller posterior cerebral and cerebellar areas in the brain. TS idea that chromosomes are important in gender development.
IDA
Deterministic
Cant control genes, however, neuroplasticity of the brain suggests brain can form new connections and even increase in size .:. neuro rehabilitation can be used as treatment
reductionist
cruel to suggest differences in the complexity of gender are is a result of chromosomes as this approach reduces the complex idea a Agenda down to which chromosomes you have as a result of prenatal testosterone exposure I’m fails to account for external factors .:. can be argued to be over simplified explanation
