Unveiling the Intricacies of Human Sexuality: A Comprehensive Exploration

1. Sex and the Brain

2. Sex is Complex • Sex – a person’s genetic biological characteristics: • Male, female, a continuum between the two • Sexual orientation – who you are attracted to: • Opposite sex • Same sex • Both, neither • Gender – social roles assigned by biological sex. • Sexual identity – which sex you feel you are, independent of biology. • Transsexuals, transvestites

3. Sexual Behavior • Phases of sexual response are the same across species. • Behavior results from many circuits, including hypothalamic activation, environmental inputs, hormones. • The cortex decides what is and is not sexually stimulating. • Sexual scripts – learned ways of responding in sexual situations.

4. Human Sexual Response

5. Sexual Dimorphisms • Male and female brains differ because male and female bodies differ. • The most distinct dimorphisms are related to reproductive behaviors. • Many other sex differences have been claimed in the literature but these do not hold up well. • Few cognitive differences exist in behavior once the impact of culture/socialization is controlled.

6. Sex Differences Claimed • Women are better at verbal tasks – false. • Men are better at spatial tasks and math – largely false. • Women are more emotional, men are less emotional – false, except for expressivity. • Women talk more than men – false. • Men are more aggressive and more violent – true.

7. Impact of Testosterone • Testosterone is not responsible for the masculinization of the male brain. • Estrogen, binding to estradiol sites, results in masculinization of a developing fetus. • Females do not produce surges of estrogen early in development and so miss this stage. • Testosterone organizes masculinization early on and is needed again to trigger puberty.

8. Male vs Female • Because hormones trigger masculinization, it is possible to have male females (genetically XX) and female males (genetically XY). • Genetic males with a defective androgen receptor will develop as female. • Genetic females with congenital adrenal hyperplasia (CAH) have unusually large amounts of circulating androgens.

9. Homosexuality • Defined as sexual attraction to members of the same sex. • Large-scale studies show that neither early childhood experiences nor learning accounts for homsexuality. • Postmortem studies suggest the SCN of the hypothalamus may be responsible. • Hamer’s studies suggest a genetic basis.