Lecture 12 - Biology of Love Flashcards
What is love? Explain through two different views.
The physicist says love is chemistry - it is a powerful neurological condition like hunger or thirst, but more permanent. While lust is a temporary passionate sexual desire involving the increased release of chemicals.
The psychotherapist = unlike us, the ancients did not lump all the various emotions that we label love under the on e word - they has several different words for love including: Philia = brotherly love Eros = sexual love Pragma = mature love Agape = unconditional love
What are the three love systems?:
Lust, attachment and attraction
Discuss Lust in terms of chemicals, brain systems, evolutionary function and shared ancestry with mammals
Chemicals = testosterone, oestrogen.
Brain systems = Mesolimbic dopamine pathway.
Evolutionary function = seeking sex.
Shared ancestry = Deeply!
Discuss attachment in terms of chemicals, brain systems, evolutionary function and shared ancestry with mammals
Chemicals = oxytocin, vasopression.
Brain systems = nucleus accumbens, ventral palladium, media insula and ACC.
Evolutionary function = maintaining LTR and raising children.
Shared ancestry = mother-offspring bond maybe.
Discuss attraction in terms of chemicals, brain systems, evolutionary function and shared ancestry with mammals
Chemicals = dopamine.
Brain systems = central dopamine pathways.
Evolutionary function = Narrowing down to one partner
Shared ancestry = Yes, probably
What is lust?
Lust is a sex drive. Made from testosterone and along the HPG axis. Firstly, the hypothalamus releases GnRH which stimulates the anterior pituitary to release FSH and LH, then LH stimulates the Loydig cells to release testosterone. FSH stimulates the Sertoil cells to release other hormones which bind to testosterone keeping it at high concentration. Finally, it negatively feeds back to anterior pituitary, inhibiting further release of FSH. Testosterone negatively feeds backs to hypothalamus and pituitary, inhibiting release of GnRH, FSH and LH.
Administration of testosterone to castrated animals restores their sex drives.
Women with high circulating testosterone have higher libido’s and testosterone increase libido in men and women alike.
Discuss the effects of testosterone on Love and lust
Administration of testosterone to castrated animals restores their sex drives.
Women with high circulating testosterone have higher libido’s and testosterone increase libido in men and women alike.
It is lower in married men and fathers - when they don’t need to mate as much or feel lust (Gray et al., 2005).
It is associated with lower relationship satisfaction - they are seeking other mates.
Associated with interest in erotica and antisocial behaviour.
Looks like a ST sexual strategy, but one that is flexible.
Discuss sex drive and estrus
Rising estrogen causes estrus in female mammals. No estrus in humans, but estrogen rises up to fertile window of menstrual cycle - increases sex drive during fertile time.
Discuss attraction and selecting a partner
Narrowing down lust towards one individual. Most societies exhibit romantic love (Fisher & Jankowiak, 1992). Love is a human universal.
The physiological reasons for attraction include - increased energy, sleeplessness, trembling, flushing, increased heart rate, dilated pupils, anxiety or fear, intrusive thoughts.
The psychological reactions include - anxiety or fear, intrusive thoughts, sexual desire, desire for emotional union.
Discuss what neurotransmitters are active in the attraction process
Effects are very reminiscent of monoamines (dopamine, serotonin, norepinephrine). So blocking dopamine in rats reduces proceptive behaviours.
Dopamine gives individual experiences of euphoria, loss of appetite, sleeplessness, mental alertness, fear and anxiety if too high though!
Norepinephrine has many similar effects as dopamine. And is involved in imprinting in birds.
High levels of serotonin associated with sexual satisfaction and lack of sexual interest. Also associated with loss of appetite, happiness, sleepiness and lack of anxiety. Low serotonin implicated in obsessive compulsive disorder.
Cortisol levels higher in those who have recently found love (Marazzitti & Canale, 2004). And acts to release energy by making glucose available in the blood.
What brain areas are involved in attraction?
Mesolimbic pathway involved in dopamine action for many motivated behaviours like seeking preferred food and drugs.
Discuss if attachment has shared ancestry
Prairie voles - highly social, monogamous and form lasting pair bonds after mating. Both parents take care of the offspring and young voles stay in the nest for several weeks beyond weaning. Selective aggression towards con specifics.
Whereas montane voles are solitary, promiscuous and do not form a pair bond after mating. Males do not participate in parental care and mothers abandon pups in 2-3 weeks after birth.
Prairie voles have much higher oxytocin receptors than montane, and much more active vasopression receptors.
If you increase the number of recpetors using genetic engineering, montane voles behaviour similarly to prairie voles.
It has been found that mammals with more microsatellite DNA are more monogamous, whereas vasopression doesn’t seem to have an impact.
Discuss attachment and pair bonding
Mutual territory defense, with shared nest building. Mutual feeding and grooming, and close proximity. Feelings of separation anxiety occur and both share parental care.
Discuss attachment in human
62% of variation in men and 40% in women due to genes.
Polymorphisms of vasopression receptor gene associated with EPC in women (but not men).
Baumgartner et al. (2008) found more likely to share is increased oxytocin (trust that partner will return altruism)
Discuss the effects of oxytocin on love
Oxytocin increases perception of facial attractiveness and trustworthiness.
It increases in-group favouritism and promotes lying to benefit the in-group (De Dreu et al., 2014).
