Lecture 14 - Sexual orientation Flashcards
What is sexual orientation
It is the way people identify their desire towards the same, the opposite or both sexes.
Most homosexual behaviou occurs in those what do not identify as exclusively homosexual. Animals often demsontrate homosexual behaviour, but less frequently are exclusively homosexual.
Why study homosexuality
Social reasons such as understanding others. Political reasons such as gay marriage.
And the psychology of sexuality. What happens when each sex doesn’t have to compromised with the others preferences.
How heritable is homosexuality
52% of male MZ twin pairs have same sexual orientation. 22% of DZ twins do, but 11% of adaptove brothers do.
Therefore fairly high heritability, there is no effect of shared family environment. Slight birth order effect, where younger brothers are more often gay than older brothers.
Gay gene studies are inconclusive.
Can you change sexual orientation?
Most do not want to change, despitre depression, anxiety and suicide. Many gay men have tried to become straight by psychoanalysis, prayer-based conversion and other treatements. But the APA (2009) concluded there is no evidence convincing that conversion therapies are effective. Rather, they may actually be harmful, increasing the risk of depression and thoughts of suicide.
Why did homosexuality evolve?
Homosexuality has been part of the human experience since its inception (Kirkpartick, 2000).
There exists robust evidence that homosexual behaviour and other nonreproductive sexual behaviours are the products of a long evolutionary history that occured independently of human culture (Vasey, 1994).
There are 3 hypothesis about same-sex sexual behaviour. 1 = same-sex sexual behaviour provides social glue. 2 = same-sex sexual behaviour diminishes sexual aggression and conflict. 3 = same-sex sexual encounters provide practice for courtship, mounting or other behaviours necessary for reproduction.
Discuss homosexual behaviour in nonhuman animals
This may be due to affiliation or dominance. But some animals have exclusive homosexual sexual orientation.
Discuss brain anatomy as a part of orientation
Some evidence of size difference in third interstitial nucleus of the anterior hypothalamus.
A study in rams replicates hypothalamic size differences.
Discuss homosexuality cross-culturally
Exclusive homosexual orientation is not that common cross-culturally. However, 49/76 of human socieities surveyed in 1950 homosexual behaviour was accepted in some form. Most of the time this behaviour occurs alongside heterosexual behaviour.
Definition and attitudes towards homosexuality differ. One trend is that in some places (even prison), the penetrator is not gay, just the penetratee.
In the US it is often experienced as experimentation, and in China and India where access to females is restricted, “the boys have to do something”.
What is the hypotheses for the existence of homosexuality
Homosexuality is a byproduct of characteristics women find attractive. Feminizing alleles hypothesis (Miller, 2000), suggested that women prefer men who are kind, sensitive, empathic and faithful. Homosexual men get too many feminizing genes - not much support for this.
Gay uncle kin selection hypothesis. This suggests that every older brother a man has roughly doubles his chances of being gay. A survey of gay uncles in USA found no more investment in nieces and nephews. Gay men have more fertile mothers, sisters and aunts.
Balancing selection hypothesis. Suggests that fitness costs of one pheneotype are balanced by enhanced fitness of related phenotype. Greater fertility in ascending female kin or larger family size. Many studies have shown this effect only in maternal kin, suggesting an X-linked trait. But this likely only applies to men, and limited variance explained leaves plenty of room for other explanations.
Gay germ hypothesis. Heritibility for homosexuality is low to moderate, and greater concordance among twins who shared an amniotic sac. Older brothers effect is suggestive.
What is the bimodel?
True bisexuality and asexuality are rare. Most bisexuals have significantly stronger attraction to one sex. Bisexuals include 1-4% of the population. Biphobia is a fear of bisexuality, which is common in both gay and straight populations.
A study found that men who identified themselves as bi were exclusively genitally aroused by either men or women, but usually men. However, more recently a study has found males who identify as bi are genitally aroused by bother males and females (Rieger 2011).
The 2011 study used a much more specific sample. On average, the bisexual men in the study had distinctly bisexual patterns of both genital and subjective arousal.
What is the hypothesis for female sexual fluidity
Men find lesbian sex arousing.
More ancestral based, rape left some ancestral women without paternal resources to allocate to their children, and turned to other females. Also, they will have encountered women who exhibited strong alloparenting potential.
What is the affiliation hypothesis
Sex isn’t just for making babies. There is a reward system around it. Same-sex/homosocial bonds are important throughout evolutionary history. 89% of young birtish men reported having kissed another man of the lips.
One of the prinicple hormones underlying parental behaviour is progesterone. It implicated the psychology of affiliation. In female rates affiliative behaviour is greated during high progesterone period, and negative is assocated with sexual motivation. It correlated with homoerotic motivation in women. Men who have high progresterone who were primed with affiliation showed the largest increase in homoerotic motivation.
Discuss the research behind homoerotic motivation decreasing during ovulation
A correlation between conception risk and homoerotic motivation has been found to be very high. Diamond and Wallen (2011) found that, in a subset of non-lesbian women who felt that there was a role for choice in their sexual desires, homosexual fantasies and desires decreased around ovulation. Ovulation is a cue that the benefits of reproductive sex outweigh the benefits of affiliative sex.
