5 - HORMONES AND (SOCIO)SEXUAL BEHAVIOURS Flashcards
hormonal influence in childhood
- sex hormone levels remain at a constant level (low)
- ovaries don’t produce female sex hormones yet
- testes only produce male sex hormones in embryonic development and just after birth and then stop
- no fertility
- no secondary sexual characteristics
- no display of complete sexual behaviour sequence
- sex differences in non sexual behaviour?? (unclear)
hormone influence in puberty
- increased hormone levels
- initiated and controlled by hypothalamus
- results in maturation of reproductive system and gamete production
- development of secondary sexual characteristics
- ability to display complete sexual behaviour sequence
- occurs over a period of time (not a single event)
- trigger = not known (one possible factor for girls is body mass??)
hormone influence in puberty
model
1 - hypothalamus receives signals (unknown what)
2 - hypothalamus releases GnRH (gonadotropic releasing hormone - causes the release of gonadotropics - which then stimulate the gonads)
3 - in response, pituitary gland releases two gonadotropins (FSH=follicle stimulating hormone)(LH=lutenising hormone)
ovaries response = release large amounts of estrogen and small amounts of androgens
testes response = large amounts of androgens and small amounts of estrogens
lots more hormones involved but don’t need to know
what is a ‘tropic’ hormone
a hormone that makes its target structure respond in some way
stimulating/activating hormone
mature reproductive behaviour in MAMMALS
- sexually dimorphic (sex specific)
- instinctive (given a specific state, a specific behaviour will almost certainly occur)
- controlled by hormones
- organisational level = development of structures
- activational level = display of specific behaviours
rats reproductive sequence
- female approaches make and must be in state to be fertilised
- sniffle and nuzzle
- rapid ear wiggling
- hopping (both sexes)
- lordosis and mounting
- grooming of genitals
- female = immobility
- male = refractory = any new female won’t be able to attract him in this phase
sexual behaviour in most female MAMMALS
- only sexually active during the fertile phase
- only when sexual action can lead to fertilisation
- due to surges of hormones
sexual behaviour in males
- depends on presence of androgens (not their exact level)
- castration at birth (no androgen) = no sexual behaviour
- castration in adulthood = decline in sexual behaviour
- testosterone therapy = restores sex drive to pre surgery levels (shows it’s definitely due to androgens and not castration directly)
statement:
- progesterone follows estrogen (rises and falls after it - only slightly non aligned)
- both decline at the beginning of a behavioural estrus (during ovulation)
-
sex drive in male RATS
- there is natural variation in sex drive (measures by copulatory score - how many times the male responds to a female in estrus)
- some could have natural low, medium or high drive
- it’s constant and doesn’t change over time
- increasing testosterone doesn’t increase sex drive past a certain point (the individuals natural drive)
- giving a low dose after castration will increase drive, subsequently giving a higher dose won’t increase it further
- high drive = largest SDN-POA
social status and sexual behaviour
- in social animals, social status can determine sexual behaviour
1 - mainly females with offspring, few adult males
- young males leave (eg lions, elephants)
- young females leave (eg bonobos, gorillas)
2 - similar numbers of males and females
- both young males and females leave (eg humans)
3 - alpha pair
- one pair reproduces, all others (unrelated?) help raising the offspring (eg marmoset)
- social static determines sexual behaviour
- social suppression of reproductive behaviour (social hierarchy) in some
- alpha pair in wolves as they’re the parents and older siblings help raise younger siblings before leave pack
how social suppression in alpha pair groups works
- week 5, pg 6*
- same layout as hormones and social learning
1 - social signals (danger) to cortices
2 - sends signals to amygdala
3 - sends signals to hypothalamus
4 - the part where hypothalamus sends signals via sympathetic PNS to adrenal medulla and produce adrenalin
-
NORMAL STRESS RESPONSE - negative feedback
4 - hypothalamus also releases CRH (corticotropin releasing hormone)
5 - activates pituitary gland to release ACTH (adrenocorticotropic hormone) which activates adrenal cortex
6 - adrenal cortex then releases GC (glucocorticoids)(large group of hormones)
7 - GC have inhibitory effect on hypothalamus - inhibits hypothalamus from releasing CRH - reduces circuit
-
PERSISTING STRESS SIGNALS (eg constant stress from socially higher individual)
- hypothalamus constantly activated by environment
- conflicts with internal signal which tries to shut down hypothalamus
- conflicting signals then cause the hypothalamus to no longer be able to release GnRH (gonadotropin releasing hormones)
- so gonadotropins won’t be produced by the pituitary gland (FS and LH) so no sexual maturation of the gonads
dissociation of sexual behaviour in ANIMALS
- generalisation (includes homosexual behaviour, which isn’t used for reproduction - common in animals)
- all primates have bisexual individuals but it isn’t the norm
- little dissociation (sexual behaviour used for other things eg relaxation and making friends)
- EXCEPTION = bonobos (have sex facing each other + use sex for other purposes other than reproduction)(most sex not for reproduction)(pretty much all bisexual)
dissociation of sexual behaviour in humans
- almost total dissociation
- little sex specific behaviour (almost none)
- because of high variability
- social / cultural variations
- inter-individual variations
- intra-individual (eg contextual) variations
- some relationship between hormone level and sexual behaviour (no sexual activity before puberty - similar to other animals)
hormones + sexual behaviour in HUMANS
- general pattern of hormones SIMILAR TO other ANIMALS
- testosterone increases rapidly until about early 20s where it slowly declines until about 60 and then more rapidly declines
- estrogen slower peaks between ages of 12 and 13 and then rapid peaks and troughs until menopause around mid 40s
- peaks due to mensuration
DIFFERENT FROM ANIMALS
- sexual behaviour emancipated from menstrual cycle (humans and bonobos)
- female humans sexually responsive to androgens (when given testosterone)
TESTOSTERONE AFFECTS THE SEXUAL BEHAVIOUR OF BOTH MALES AND FEMALES
