The Role of Hormones in Sex and Gender

Question 1

Males and females produce different sex hormones in varying quantities.

Answer 1

Besides affecting the development and functioning of various bodily organs (e.g. causing the menstrual cycle in women) these sex hormones also appear to have an effect on behaviour, explaining some of the differences between the behaviour of males and females).

Question 2

Evidence suggests that differences in verbal and spatial abilities, memory & aggression are linked to

Answer 2

differences in hormone secretions between males and females.

Question 3

Gender identity may be influenced by ‘hormonal imprinting’

Answer 3

before birth, so that prenatal androgenisation, for example, exposure to high levels of the androgen testosterone before birth, may lead to a more masculinised brain and behaviour

Question 4

TESTOSTERONE

Answer 4

(an androgen) is produced in greater quantities by males than females (females produce 10% of the amount found in males).
It affects several ‘typically male’ behaviours such as dominance, aggression etc.
It is produced by the testes.

Question 5

what is the effect of testosterone early on

Answer 5

The influence of testosterone on sexual differentiation of a foetus begins early in pregnancy (around 8 weeks), once the gonads have developed into testes.
XY foetuses have higher levels of testosterone than XX foetuses, particularly between 8 and 24 weeks gestation.
A surge of testicular hormones after birth makes testosterone higher in boys than in girls, for about the first six months.
Testosterone influences the development of external genitalia (penis), as well as the brain (hormonal imprinting – brain masculinisation) and behavior.

Question 6

Testosterone also stimulates the

Answer 6

development of male secondary sexual characteristics that emerge at puberty e.g. facial hair, deepening of the voice.

Question 7

Dabbs et al. (1995)

Answer 7

studied 692 male prisoners (by taking saliva samples) and found that violent offenders had higher testosterone levels than non-violent offenders.
Inmates with higher testosterone levels also violated more rules in prison, especially rules involving overt confrontation.

Question 8

Research into the role of testosterone:Young (1966)

Answer 8

Male hormones, including testosterone, were administered to female rats (and female hormones to male rats).
The effect was an irreversible change in usual gender-related behaviours (e.g. female rats mounted other rats), suggesting that hormones like testosterone have a key role in determining gender behaviour.
Testosterone may alter the Sexually Dimorphic Nucleus (SDN) in the brain, resulting in its masculinisation.

Question 9

Research into the role of testosterone:Money and Ehrhardt (1972)

Answer 9

Reported on a sample of girls whose mothers took drugs containing testosterone during pregnancy.
The girls exhibited male-type behaviours e.g. playing energetic sports, and an absence of female-type behaviours e.g. playing with dolls.
This suggests that testosterone has a strong influence on gender behaviour.

Question 10

Testosterone and Brain Development

Answer 10

Testosterone is thought to act on the hypothalamus; without this, the brain develops as a female type.
It is associated with masculinisation of the brain, such as the development of brain areas linked to spatial skills.
It is also associated with male-type behaviours such as competitiveness and aggressiveness.

Question 11

There are differences in the hypothalamus of males and females,

Answer 11

with the Sexually Dimorphic Nucleus (SDN) being larger in males.

Question 12

Swaab (1985) found

Answer 12

that the SDN was twice the size in male brains compared to female brains, thus supporting the idea that testosterone is involved in the enlargement of the SDN in humans.

Question 13

The Batista Family (Imperato-McGinley et al., 1974)

Answer 13

Four children were born with external female genitalia and raised as girls even though they had XY chromosomes.
When they reached puberty, the surge in testosterone levels led to the production of a male hormone (dihydrotestosterone) which they had lacked before birth. This hormone led to their belated masculinisation and caused their male genitalia to appear externally.
It is said that the ‘girls’ accepted their new male role without any difficulty.
The role of socialisation appeared to be overridden by biological factors and the researchers concluded that biology was all important. Their ability to adopt a male gender identity and gender role suggests that their testosterone had pre-programmed masculinity in their brains.

Question 14

The Batista Family (Imperato-McGinley et al., 1974)
However,

Answer 14

it has also been suggested that the ease of transition from female to male highlights the importance of culture - in a community prepared to accept more fluidity in gender roles it seemed to be relatively easy to move between roles.

Question 15

OESTROGEN

Answer 15

promotes the development and maintenance of female characteristics of the body (e.g. enlarged breasts and hips) and regulates menstruation.

Question 16

Aside from influencing physical changes to the body, such as the development of breasts, oestrogen also has psychological and behavioural effects,

Answer 16

such as premenstrual tension (PMT), which is associated with emotionality, irritability and irrational behaviour, as well as lapses in self-control.

Question 17

Oestrogen plays a role in feminising the brain

Answer 17

with oestrogen promoting neural interconnections for a more ‘distributed’ female brain (equal use of both hemispheres – bilateral patterns).

Oestrogen is also associated with female-type behaviours such as co-operation and sensitivity.

Question 18

Fitch and Denenberg (1998) found

Answer 18

that suppressing production of oestrogen by removing ovaries from female rats as late as 16 days after birth led to changes in the corpus callosum (connects the left and right hemisphere) area and therefore affected connectivity between hemispheres in adults.
The findings suggest oestrogen is involved in feminisation of the brain even after birth - thus, there is a later sensitive period for oestrogen-regulated feminisation of the brain compared with testosterone-regulated masculinisation.

Question 19

OXYTOCIN

Answer 19

OXYTOCIN (the ‘love hormone’) is produced in (and outside of) the brain by both males and females to control key aspects of the reproductive system.

Question 20

what does oxytocin do

Answer 20

Its action is greater in females as it combines with oestrogen to enhance each other’s effect.

Oxytocin helps to facilitate childbirth (by helping to stimulate contractions) and breastfeeding (by stimulating the ‘let down’ reflex).

Question 21

Oxytocin also increases significantly during

Answer 21

sex (though it drops in males immediately after orgasm, which explains males’ sudden loss of intimacy at this point).

Oxytocin also affects female social behaviour such as mate selection, ‘nesting’ behaviour (preparing the house for new offspring), monogamy and pair bonding, as well as the nurturing, acceptance and protection of offspring.

Question 22

Research into the Role of Oxytocin:
Van Leengoed et al. (1987)

Answer 22

Injected an antagonist of oxytocin into female rats shortly after they had given birth to block the receptors of oxytocin/inhibit oxytocin production.
Mothers treated in this way showed a delay in maternal behaviours, such as picking up and grooming their pups.
When the effects of the antagonist wore off, normal maternal behaviour was seen.
The findings support the idea of oxytocin being involved in the promotion of maternal behaviour.

Question 23

The biological view of gender is supported by cross-cultural studies that have found universal features of gender.

Answer 23

For example, in all cultures studied, men are found to be more aggressive than women.
This suggests that male traits, such as aggression, are biologically determined through exposure to testosterone.

Question 24

However, it is important not to ignore the fact that there are considerable differences between some cultures in their gender behaviour. When different cultures behave in different ways this supports a role of learning.

Answer 24

Mead (1935), for example, documented how three tribal societies living in close proximity to each other in Papua New Guinea had very different gender roles. Findings like this suggest that even though biological factors influence gender behaviour, they are heavily modified by learning.

Question 25

Evaluation of Genes and Hormones on Sex and Gender

Answer 25

It is clear from a range of studies involving humans and other animals that chromosomal and hormonal differences between males and females affect a range of masculine and feminine behaviours, which supports the biological view.
However, much of this research is correlational

Question 26

Extrapolation Issues:

Answer 26

However, where the research was carried out with non-human animals there is a need for caution in assuming that the results apply to humans.
The physiology of humans and animals, like rats and mice, especially in terms of brain functioning is very different and human development and behaviour are much more subject to social and cultural influences.
Therefore, such research only provides limited support for the idea that hormones influence our behaviour.

Question 27

It is fairly simplistic to think of testosterone as a male hormone and oestrogen and oxytocin being female hormones.

Answer 27

Research shows all three exert important influences on both males and females (albeit in varying quantities).
Therefore, this is a reductionist viewpoint and means that a complex issue is oversimplified.

Question 28

It is also reductionist to perceive single/specific hormones as having exclusive effects upon sex and gender.

Answer 28

Hormones are often part of biological mechanisms that exert multi-faceted and complex actions upon the body and behaviour, for example the interaction of sex chromosomes, the SRY gene and gonadal hormones.
Additionally, such an explanation does not take into account the complex social structures and influence of nurture that may also play a part on our gender identities.