Week 9-Gender and Sexual Behaviour

Question 1

Why is sex important?

Answer 1

Sexual reproduction:

• Reduces the chance of passing on mutations
• Gives diversity (to adapt to a changing environment)
• “survival of the fittest”

Without offspring, no species can survive.

Question 2

Which species produces in an asexual way?

What is asexual reproduction?

Answer 2

Asexual: amoeba

When a species makes more of itself without exchanging genes through sex.

Question 3

What is DNA?

Answer 3

Is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA). Mitochondrial DNA are passed from mother to offspring.

Question 4

What are genes?

Answer 4

• A subsection of the DNA

- Genes are made up of DNA. Some genes act as instructions to make molecules called proteins.

Question 5

What are chromosomes?

Answer 5

A chromosome is a long DNA molecule with part or all of the genetic material of an organism.
Made up of proteins

Question 6

Where are chromosomes found?

Answer 6

Chromosomes found in the nucleus

Question 7

How many chromosomes do we have?

Answer 7

46 chromosomes (23 pairs)

Question 8

Define dimorphic

Answer 8

Humans are dimorphic – exist in two genetic forms
genetic information on the sex chromosomes (X, Y) normally determines male or female development.

XY-MALE
XX-FEMALE

Question 9

Define sex

Answer 9

Sex (anatomy and biological characteristics)

• Hormonal
• Internal and external genitalia

Question 10

Define gender

Answer 10

Gender: social role or identity

• Socially constructed norms, roles, relationships
• Can be changed over time and across cultures

E.g. heels, skirts used to be worn by men. Colours associated with girls or boys.
Social gender norms change across time and cultures.

Question 11

Define Transgender

Answer 11

Transgender: internal gender identity doesn’t match the sex they were assigned at birth. (Non-binary)

Question 12

What is intersex (hermaphroditism)?

Answer 12

• Mix between female and male genitalia (both vagina and penis)
• XX intersex: chromosomes woman, internal ovaries of woman, but external genitals appear male–> fetus exposed to excess male hormones before birth
• XY intersex: chromosomes of a man, but external genitals incompletely formed, ambiguous or appear female. Internally, testes may be normal, malformed or absent–> problems with testes, problems with testosterone formation, problems using testosterone

Question 13

David Reimer case

“The boy with no penis”

Answer 13

Circumcision went wrong lost penis 60s

Should’ve undergone an operation and told he was a girl (psychological torture) led him to commit suicide.

Question 14

Sex Chromosome abnormalities- Turner’s Syndrome

Answer 14

ONLY ONE FUNCTIONAL CHROMOSOME
2nd X chromosome missing/ altered
-affects females (embryo with Y chromosome not viable)
-not inherited(ovaries don’t work properly)

Physical traits

• Shorter than average
• Wide neck/ puffy hands
• Weaker bones/ hearing difficulties
• Ovaries don’t work properly
• Oestrogen / progesterone are reduced—> take hormone replacement therapy
• May not have periods

Question 15

Sex Chromosome abnormalities- Klinefelter syndrome

Answer 15

Additional X chromosome (XXY)

• Chromosomal disorder in males
• Don’t make enough testosterone(Reduction of testosterone)
• Often don’t make any sperm
• Taller than average height
• Can be increased learning and behavioural difficulties
• Taking hormone replacement can increase muscle strength, body hair, reduce fat on the abdomen, stronger bones.

Question 16

Hormones and Sexual Development- HYPOTHALAMUS & PITUITARY GLAND
What do they do? In terms of sexual hormones

Answer 16

Hypothalamus releases gonadotropin-releasing hormones (GnRH)

Controls secretion of gonadotropin hormones from pituitary gland:-

• LH (luteinizing hormone)
• FSH (follicle-stimulating hormone)
• In women, LH and FSH encourage estrogen production
• In men, LH encourages testosterone and FSH matures sperm cells

-Lower melatonin (more light) increases gonadotropic secretion.
Offspring born when the most chance of survival

Question 17

Hormonal Control of Sex- Explain how gonads and the pituitary gland have hormonal control of sex

Answer 17

Ovaries and testes release steroid sex hormones:

• Ovaries release estrogen (oestrogen) and progesterone
• Testes release testosterone

The pituitary gland regulates this release

Men have “female” hormones and females have “male” hormones – but in different concentrations.
Men have more androgens (e.g., testosterone) – females have more estrogens.

Question 18

Give Examples of THE ROLE OF HORMONES IN SEXUAL DEVELOPMENT

Answer 18

Example 1: Pregnant guinea pig injected with testosterone (Phoenix et al., 1959)
-Females showed more masculinised sexual behaviour
Prenatal testosterone affect the organisation of adult behaviour

Example 2: Newborn female rats treated with estrogen = didn’t show more female sexual behaviour.

Example 3: Anne S. (Pain during sex and could not get pregnant)

• chromosomally male (XY); Internalized testes, but no ovaries; hormone levels of a man
• Androgenic(Testosterone) insensitivity syndrome (normal male testosterone levels, but no response to them
• She does respond to estrogens,– leading to the development of female secondary sex characteristics

Question 19

Explain the importance of Testosterone

Answer 19

Testes – primarily responsible for the release of testosterone

• Essential for the development of the male reproductive system
• At puberty, regulate the development of secondary sex characteristics: muscle development, facial hair (cf. mane of a lion)
• Also causes baldness in men.

Testosterone DECREASES with age.

• Females have 10% of testosterone levels found in men
• Hormone levels can fluctuate through the day: affected by stress, exertion, aggression etc.

Question 20

Testosterone in Athletes

Answer 20

• Form of doping to improve athletes performance
• ->increase muscle development, strength, endurance
• Some female athletes have naturally higher levels of testosterone
• Increase incidents of cardiovascular disease
• Potential prostate cancer risk associated with testosterone supplementation
• Minor side effects: acne; hair loss

Question 21

Female hormones: Role of Estradiol & Progesterone

Answer 21

• Low during childhood
• Estrogen levels increase dramatically at puberty
• Control maturation of female reproductive system and development of breasts
• Hormones follow the regular cycle of 28 days

Question 22

2 phases in the menstrual cycle

Answer 22

• Follicular phase- the start of menstruation till ovulation (first 14 days) Egg inside follicular.
• Luteal phase- Moment of ovulation till next menstruation (last 14 days) Egg is out of the ovary

28 days in total

Question 23

Difference between male and female brain structures

Answer 23

Are these dimorphic or on a continuum?
What about brain-body size?
Aspects of caution can’t overgeneralize.

Hippocampus bigger in females. (Thus females have better memory)

Amygdala larger in males (males are more emotional)

Question 24

SDN (sexually dimorphic nucleus)

Answer 24

SDN under the influence of testosterone so grows larger in males.

Question 25

Reproductive Cycles | How long does it take for males and females to reproduce themselves? -Animal Kingdom

Answer 25

FASTER PRODUCTION OF SPERM IN A DAY. -Man with most children had over 1000 children (possibly up to 2000). Genghis Khan is an ancestor of 0.5% of the world’s population -Female with most children had 69 Sperm are mobile: males of the species tend to be more mobile and go out to find a mate -Females tend to be picker about the quality of their mates (limited number of chances of pregnancy) -Men tend to need to show off more: louder, larger, brighter, more ‘combative’ -Polygyny is very common among mammals (one male to many females), polyandry and monogamy is rare in animals.

Question 26

Dopamine-The pleasure chemical | Why is Dopamine important in sexual behaviour?

Answer 26

Dopamine high is addictive in sex. (Gives pleasure) Elevated dopamine levels increase sex drive even in non-relational situations. Bungee jumping- huge dopamine rush. A shot of dopamine in the brain makes you want to have sex. Euphoria.

Question 27

Erection- How does erection occur?

Answer 27

CONSEQUENCE OF SEXUAL AROUSAL caused by: - Increase in Blood flow into the tissue in the penis – spinal reflex - Erection controlled by the parasympathetic division of ANS(autonomic nervous system) Nerve endings widen arteries by releasing:- - Acetylcholine - Vasoactive Intestinal Polypeptide - Nitric Oxide (NO important) Viagra – interferes with nitric oxide metabolic pathway, which causes the arteries to widen more and for erections to last for a longer period. Sympathetic division (of AO) stimulates emission (ejaculation) -Muscle contractions -Constriction of arteries CLITORIS -an erectile structure. It becomes engorged in a similar manner to the penis.

Question 28

Sexual Arousal

Answer 28

Neural regulation across genders is surprisingly similar Sexual arousal can result from:- -Psychological (top-down our brain controlling our bodies) -Sensory (bottom-up from sexual to the brain) -Tactile stimulation(bottom-up from sexual to the brain) Duration of each phase varies Control of sexual response:- - Cortex - Spinal cord - -> Top-down and bottom-up

Question 29

Orgasm: Brain Location?

Answer 29

- Temporal lobe epilepsy -->some patients experience orgasmic aura at the start of their seizures (Janszky et al., 2004) So pleasurable that they refuse treatment - In the surgical treatment of epilepsy, electrical stimulation of medial temporal lobe or basal forebrain-->sexual arousal - Georgiadis et al., 2006: PET scanner of an orgasm shows a decrease in blood flow in left lateral orbitofrontal cortex when compared to control conditions (e.g., clitoral stimulation/ imitation) -->behavioural disinhibition during orgasm? Deactivation of temporal lobe related to high sexual arousal --> Mixed findings of the brain mechanisms of an organism

Question 30

MATING STRATEGY OF VOLES | Hormones: Monogamy or Polygyny

Answer 30

Different sexual behaviours between voles. - Prairie Voles: Monogamy - Muntane Voles- will leave partner after sex 3 chambers: partner; stranger; neutral. How much time each vole spend in each chamber. Prairie stays longer in partner chamber, muntane spends more time in the neutral chamber. -Receptors(Vasopressin and Oxytocin ) for both are different in prairie voles and montane voles Oxytocin found in the nucleus accumbens part of the reward system- dopamine.

Question 31

Which 2 hormones increase pair bonding?

Answer 31

- Vasopressin | - Oxytocin

Question 32

Role of Vasopressin and Oxytocin | Cause and Effect?

Answer 32

-If you give vasopressin antagonists to male prairie vole (suppressing)before mating it prevents him from forming a pair-bond - Male given vasopressin: quickly forms strong preference for her - Overexpression of vasopressin receptors:- pair-bonding(LONGER & QUICKER bonding) - Vasopressin increases paternal activities -But administering vasopressin/ oxytocin to naturally promiscuous voles doesn’t evoke pair-bonding – perhaps because they do not have receptors in place. No effect.

Question 33

Hormones & Sexual Behaviour- | Castration and injections

Answer 33

CASTRATION-To decrease testosterone levels of these men. Heim & Hursch (1979) found castration on men convicted of sex crimes: -50% stopped exhibiting sexual behaviour -25% gradual decline in sexual behaviour -10% no change HORMONE AGONISTS reducing levels of testosterone. - Davidson et al (1982) androgen injections to hypogonadal men: diminished functional activity of gonads. (Increase in erection and masturbation effects) - The effects were dose-dependent and temporary.

Question 34

``` Hormones & Sexual Behaviour- Ovariectomised Rat (REMOVAL OF OVARIES) ```

Answer 34

-Ovariectomized: surgical removal of ovaries -Male rats don’t mate with ovariectomised females -They don’t come on heat – loss of estrogen and progesterone normally secreted by ovaries -De Jonge et al. showed progesterone facilitates the effect of estrogen. The two work together. Lower doses position. Estrogen only less amount of lower dose position. ----Estrogen and progesterone have to work together for sexual arousal and promote sexual behaviour.

Question 35

Effect of hormones on proceptive behaviour

Answer 35

Ovariectomised female rat: - more testosterone--> more time near male rat - more estrogen --->more time near male rat - more estrogen & progesterone --> more time near male rat 2 cages of the ovariectomised rat.

Question 36

Sexual Attraction

Answer 36

Study of lap dancers (Miller et al) Amount of money dependent on phases of the menstrual cycle. High earnings during fertile phase reduction during the menstrual phase. Women that take the pill no difference in earnings, earnings were less than those who didn't take the pill. Hormones in effect sexual attraction. Sexual initiation in females-partners initiated, female initiation of sex varied a lot across the menstrual cycle. Increase of sex initiation of females during ovulatory phase (more likely to get pregnant)

Question 37

Human Love (Bartles and Zeki, 2004)

Answer 37

Human love and brain activity across different types of love: maternal (children, relatives, kids friends) vs romantic love (partner). Brain response to child and partner overlaps significantly. BRAINS REWARD CIRCUIT OXYTOCIN AND VESOPRESSIN AREAS. - Many are part of the brain’s reward circuitry - Many of these areas are rich in oxytocin and vasopressin receptors Vasopressin also linked to marriage quality

Question 38

Sexual Orientation | UK BIOBANK

Answer 38

Majority heterosexual Homosexuality varies with age- more homosexual identity in younger participants. How cultural changes are important. Cultural and societal prejudice. Higher levels in BIG CITIES. (liberal vs conservative). The genetic makeover of same-sex behaviour. Genetic vs environmental. Effect sizes of genetic traits of genetic causes for homosexuality are low. 70s- report more same sexual behaviour than the 40s. Manhatten plot - different chromosomes correlated to genes to homosexuality. Genome Y significant signals. Male-specific. 8-25% variance for same-sex behaviour. 5 GENES SIGNIFICANTLY ASSOCIATED, rest of related to environmental factors. Sex regulation- hormone regulation

Question 39

Genetics and Same-Sex Behaviour

Answer 39

Genetic influences of same-sex behaviour in homosexuals are different from genetic influences of this behaviour in heterosexuals. WEAK CORRELATION between same-sex behaviour and genetics. there is no single continuum from opposite-sex to same-sex sexual behaviour CAUTION: - same-sex behaviour (not sexual orientation or gender identity) - differences between men and women - importance of sociocultural context

Question 40

Castration = Cure For Homosexuality?

Answer 40

Alan Turing and the Enigma Thought they could cure homosexuality through castration. Interfering with biology can have a detrimental psychological impact.