ANTH 216 Exam 2

Sambia od Papua New Guinea

-"Traditional" forms of culturally conventionalized same-sex erotic practices. "Ritualized homosexuality" -Sambia believe that the male body is incapable of producing semen (which is necessary), so they need to artificially introduce semen into boys -Boys orally inseminated by older bachelor males -Sexual reproduction has 3 functions: 1- to reproduce, to create boys who will be heirs and warriors, and girls who will be traded in the marriage exchange system 2-to grow masculine boys 3-to have pleasure: first with boys (orally) and later with women (orally and genitally) -The majority of males do terminate their relations with boys once they get marries -Heterosexual mating competition is diminished as it removes young boys from the mating pool in order for older men to have access to eligible some (benefits older, heterosexual males)

What is 5 Alpha Reductase Deficiency?

-5 Alpha Reductase is only effective in when there is sufficient T available in males - if there isn't enough 5 alpha reductase, the external genitals look female -They grow up as girls and then start turning into males during puberty - pubertal testosterone masculinizes genitalia and appearance --> some adjust well to life as males, most retain female gender identity

North American Alyha

-At a young age, they began to seriously engage in activities that were exclusively masculine, and the kids who wouldn't became after alpha -Took female name, sensitive to sexual joking, generally better housewives than regular girls, curled like widows or divorcees, took female role in sex. Embarrassed by erection, imitate menstruation and childbirth, they were respected, the husband not considered homosexual

What lines of evidence support the idea that men are more competitive among themselves for mates than are women?

-Bateman-Thrivers Theory -Men are more aggressive & mature later -Almost all of same sex homicides are committed by men -Men are larger -built for combat/competition

What is the sex difference in the capacity for investment? What are the implications of this difference for men and women's mate preferences?

-Both sexes invest economically in offspring, only women invest physiologically -A man's economic well being may provide a better indicate of his value as a mate than does his physiological state -Women in better physiological condition will be better parents and therefore better choices as mates -Women and men's preferences are overall quite similar

What hormone manipulations are necessary to change male and female typical sexual behaviors (in rats)?

-Castration: removing the testes but leaving the penis intact - thus stopping or significantly reducing the flow of androgens to the brain -Manipulation of testosterone and estrogen are necessary to change these behaviors -Aromatization: the process of changing testosterone to estrogen (defeminization)

What is CGN? Behaviors that characterize it? Relation with sexual orientation?

-Childhood Gender Nonconformity -Phenomenon in which prepubescent children do not conform to expected gender-related sociological or psychological patterns, or identify with the opposite sex/gender -Athletics, aggression, rough play -Toy preferences, career ambitions/role models, cross dressing, affiliation with boys or girls, reputation as "sissy" or "tomboy", gender identity

What is CAIS? Sexually differentiated psychological traits?

-Complete Androgen Insensitivity Syndrome. -XY, but non-functional androgen receptor (AR) --> testes develop, produce testosterone --> body does not respond to androgen message --> Wolfing ducts don't develop --> scrotum and penis don't develop --> no masculinization of body and brain --> look like female -They are only discovered to be males at puberty, when they fail to menstruate -Complete inability of the cells to respond to androgens. All affected individuals are phenotypically female; they develop a normal female habitus, despite the presence of a Y chromosome

What is CAH?

-Congetical Adrenal Hyperplasia. -Enzyme deficiency --> overproduction of adrenal androgens --> females with CAH display masculinized behavior

What lines of evidence support the idea that women are more competitive mates compared to other female mammals?

-Female body fat distribution is probably sexually selected -Neotenous features (youthful)

Female and male hormones? How do they work?

-Females: estrogen -Males: androgens -Hormones are chemical messengers in endocrine. They control sexual maturity and reproduction of both sexes

How do men guard against mixed reproductive strategies?

-He can attempt to secure a sexually faithful mate; if he fails at that, he can divorce his partner and minimize investment in her offspring -Men rated sexual fidelity as the most important characteristic of a long term mate and sexual infidelity as the most negative trait

What is the difference between homosexual transsexualism and antogynephilic transsexualism?

-Homosexual transsexualism: feminine gay men who wish tho change their sex -Antogynephilic transsexualism: men who are aroused by the idea of becoming a woman

Why gay genes haven't been eliminated by natural selection: Maladaptive extreme

-If sexual orientation is polygenic in women or men, then it is possible that natural selection hasn't favored homosexuality per se. Rather, selection may have favored genes for testosterone production or some other developmental process that underlies variation in sexual orientation that is adaptive -Sexual orientation is polygenic, natural selection favors an intermediate level of prenatal testosterone and homosexuality is just a maladaptive phenotype (hypothesis not yet supported or rejected)

Inbreeding avoidance & the Westermark effect PKU example

-Inbreeding avoidance: Inbred offspring have higher mortality & infertility -Westermark effect: learned sexual disinterest between people raised together. Women prefer the smells of men with different alleles from their own -PKU (Phenylketonuria): PKU is recessive and rare - risk of suffering from it goes way up with inbreeding - 576% as likely to be in brother-sister matings

What are the Mullerian and Wolfian ducts? How do they develop

-Initially present in both males and females -Mullerian: form female internal structures -Wolfian: form male internal structures -If testes are present, testosterone develops the Wolfing ducts and MFR(Mullerian regression factor) causes the Mullein ducts to dissolve. In females, there is not MFR, so the Mullein ducts are able to develop, but the Wolfing ducts disappear - because they need testosterone to develop

What is 5 Alpha Reductase?

-It converts testosterone(T) to dihydrotestosterone(DHT) - for formation of external male genitals - it's present in the genital tissue of both males and females -It is only effective when sufficient T is available in males

What are the sex differences in minimal parental investment?

-Large difference in parental confidence (the male can't know for sure that the offspring is his) -Women can recruit investment and genes separately - some males may offer better genes than investment, and others may offer the reverse - selection favors women who get the best possible investment, even if they come from different sources -Because a man's investment and his genes are not automatically linked, men can separate their contributions, giving only genes to some of their offspring

What is MHC compatibility? Why is smell relevant? Relation to Red Queen Hypothesis?

-MHC (major histocompatibility complex) genes build our immune system - accounts for some differences in people's preferences for mates -T-shirt study: people prefer the smell of MHC-discortat partners - because that would lead to the production of more pathogen-resistant offspring. Women are choosier than men with odor because of their slower reproductive rates -Red Queen Hypothesis: predicts a mating preference fro individuals who have dissimilar MHC genes - complementary immune weapons - to produce offspring with new immune systems to fight parasites

In rats, what are male typical and female typical sexual behaviors?

-Male: mounting -Female: lordosis

Distributions of sexual orientation in males and females

-Males: Sexual attraction is discrete in males. Bimodal - has two modes. Most men fall either well toward the exclusively heterosexual or well toward the exclusively homosexual end of the continuum for all of the four sexuality dimensions measured by the Kinsey Scale -Females: Sexual attraction is a continuous trait in females. Sexual attraction in females appears to be a matter of degree. Frequencies decreased as sexual orientation went from exclusive heterosexuality to exclusive homosexuality

What are the sex differences in gene expression that we see in the mouse brain?

-Males: when they are castrated, they end up displaying female sexual behavior (no more flow of androgens to the brain) -Females: Removing the ovaries from a female rat after birth does not affect either her adult sexual behavior or maternal behavior

Brazilian travesties

-Men who enjoy anal penetration - perceived as unmasculine: this cultural classification as feminine is often reflected in the general comportment, speech practices, and dress patterns of such males -One of the most marginalized, feared and despised groups in Brazilian society -Incorporate female attribute - take female hormones -There is a strong consensus among travesties in Salvador that any travesty who claims to be a woman is mentally disturbed -A travesti is not a woman and can never be a woman, they tell one another, because God created them male -Travestis modify their bodies not because they feel themselves to be women but because they feel themselves to be feminine -Travesti values her penis, but keeps it hidden

What patterns of genital arousal do men and women exhibit?

-Men: Men showed far greater arousal to their preferred sex; gay men became more aroused to the male-male films and straight men became more aroused to the female-female films -Women: Women became aroused to both male-male and female-female sexual stimuli. Homosexual women showed an arousal pattern more like that of men; they tend to become more aroused to their preferred sex; women

Costs of mixed reproductive strategies

-Mixed reproductive strategies affect the fitness of partners negatively -Men: cuckoldry; being dupes into investing in another man's children - costs: any genetic offspring he might have will suffer because much of his investment goes elsewhere & his investment is not just wasted; it aids the offspring of his competitors -Women: When a man's extramarital partner captures some of his resources, she depletes what is available to his wife's children. A husband might completely desert his wife and commit all of his resources to a woman who initially was an extramarital partner - women stand to lose some, and possibly all of their husband's investment when he takes a lover

Name the 3 different types of reproductive strategies

-Mixed reproductive strategy (Individual tries to "get the best of both worlds") -Committed (LT), investing in relationship with mate -Uncommitted: relationships with multiple mates

Ontogeny for sexual orientation: Maternal immune hypothesis

-Mothers may develop a progressive immune reaction to fetal sons, and this immune reaction may lead to smaller birth weights and homosexuality in sons. -Some cells from a male fetus enter the mother's bloodstream, causing her immune system to react --> because the mother lacks a Y chromosome, her immune system recognizes any antigens encoded on the Y chromosome as foreign and producers antibodies attack cells bearing them --> "intimale" antibodies enter the bloodstream of the fetus and affect its development -Increases with every exposure to male fetal cells, due to the buildup of memory cells specific to Y-linked antigens -Parsimonious explanation: the maternal immune response affects sex hormone signaling in the fetus

What are the two sources of continued genetic variation?

-Mutation: Recent mutations may be chosen or rejected until they go to fixation or are eliminated. But harmful recessive mutations can persist at low frequencies (harmful recessive alleles) - recessive; so harmful effects only occur in people with two copies. Rare; so few people have two copies. Except for children of close genetic relatives -Fluctuation selection: maintains genetic variation. Mutation introduces genetic variation; fluctuation selection maintains it. Parasites impose fluctuating selection on hosts

Why gay genes haven't been eliminated by natural selection: Antagonistic pleiotropy

-Perhaps gay genes are maintained because they have different effects in different bodies -Gay genes may improve reproductive success in heterosexuals - found significantly higher reproductive success in the mothers, maternal aunts, and non-gay maternal uncles of gay me -Gay gene could increase the fitness of the sisters and other female relatives of gay me: gay gene on X chromosome would have to increase the fitness of females by only half as much because females have two X chromosomes and men only have one -Across all studies, data is equivocal

Why gay genes haven't been eliminated by natural selection: Kin selection

-Proposed that gay genes could be maintained if homosexuals compensate for their lowered fitness by altruistically increasing the fitness of close genetic relatives -The benefit of kin-directed altruism could be greater in societies where men's paternity certainty is low - the kin selection hypothesis does not explain how gay genes are maintained in present large-scale western societies in which paternity certainty is high -Samoa: Study found that homosexual men reported greater investment in their nephews and nieces than heterosexual men did (avuncular tendencies) - the increased altruism doesn't seem to outweigh the reproductive costs of homosexuality -Homosexuality seems an inefficient means of channeling reproductive effort into investment in kin

SRY gene & Y chromosome

-SRY gene is on the Y chromosome. It's the gene for testis determination. XY-->SRY gene on Y chromosome-->TDF(testis determining factor) encoded by SRY gene-->TDF causes fetal gonads to become testes -The Y chromosome determines that the testes (male gonads), rather than ovaries will form; the testes then help determine most of the differences between the sexes

Ontogeny for sexual orientation: 2D:4D (women)

-Study showing that lesbians have a shorter index finger relative to their ring finger than do heterosexual women - evidence suggests that a low 2D:4D reflects prenatal androgen exposure -"Butch" lesbians had significantly lower 2D:4D than "femme" lesbians - concluded that early androgen exposure was likely to have played a role in the sexual orientation of butch lesbians but not femme lesbians

What is the Kinsey Scale? What are the four dimensions?

-The Kinsey Scale is used to assess a subject's sexual orientation. Scale of 0 to 6 - 0 for exclusive heterosexuality and 6 for exclusive homosexuality -Four Dimensions: attraction, fantasy, behavior, self-identity -Attraction and fantasy most stable in both

What indicators of investment capacity in men do women prefer?

-Women prefer partners with good economic potential -The structural powerlessness hypothesis is wrong -Women with higher incomes placed a greater emphasis on a mate's earning potential than did women with lower incomes

How do women guard against mixed reproductive strategies?

-Women use men's sensitivity to the risk of cuckoldry in competing for mates - they attempt to make their competitors less attractive by stressing the competitor's promiscuity -Girls are willing to fight to protect their sexual reputations

Operational sex ration (OSR)

Fertilizable females/sexually active mates

Fluctuating asymmetry (FA) and hormone dependent traits - how do they reflect genetic quality?

Fluctuating asymmetry (FA) measures the fit between an organism's genotype and its environment. A symmetrical face shows parasite resistance and freedom from harmful mutations

Ontogeny for sexual orientation: Fraternal birth order

Fraternal birth order is associated with male homosexuality; the more older brothers a man has, the likelier he is to be homosexual

Ontogeny for sexual orientation: Xq28

Gene on the X chromosome that appears to be a significant factor in determining sexual orientation in males. There appears to be an increased frequency of the Xq28 marker in gay men

What are gonads?

Gonads are the primary sex organs (testes and ovaries). The glands in which gametes (sex cells) are produced

What four hypotheses have been put forward to explain why genes associated with homosexuality have not been eliminated by natural selection?

Heterozygous advantage, kin selection, maladaptive extreme, antagonistic pleiotropy

Ontogeny for sexual orientation: Heritability

Male sexual orientation is heritable. Monozygotic (identical) twin brothers of homosexuals are approximately twice as likely to be homosexual as are dizygotic (fraternal twin brothers). This finding indicates that differences in male sexual orientation are related to genetic differences, because monozygotic twins share twice as many genes as dizygotic twins

Sex differences in sociosexuality

Males are more likely to be okay with casual sex, because they are less choosy. Women are choosier with one night stands than they are with marriage partners

Ontogeny for sexual orientation: Genetics

Males may be monogenic - variation in discrete traits is often due largely to differences in a single gene - because female sexual orientation appears to be discrete, we could expect differences at a single genetic locus to explain a substantial portion of the phenotypic variation in male sexual orientation. The variation in continuous traits more often results from variation among individuals at multiple genetic loci - continuous traits are often polygenic. We might expect female sexual orientation to be a polygenic trait, because it has a fairly continuous frequency distribution

Lek Pardox

If allele A is preferred by mates over allele B, then A spreads and B is eliminated

Why gay genes haven't been eliminated by natural selection: Heterozygous advantage

Individuals who only have one copy of the gay gene and one copy of its allele are heterosexual and average higher fitness than heterosexuals with no copies of the gay gene (little support)

Activational effects

Induce adult sexual function and behavior around the time of puberty. They cause men to have deeper voices and grow hair. Women develop breast and have their menstrual cycles

Ontogeny for sexual orientation: 2D:4D (men)

2D:4D decreases with fraternal birth order - high prenatal androgen levels lead to homosexuality - findings of a lower 2d:4D in homosexuals than in heterosexual men

Ontogeny for sexual orientation: Sex hormones

Drugs for preventing miscarriage: women who were exposed to high levels of masculinizing hormones in utero because their mothers took drugs to prevent miscarriage - these girls showed increased rates of homosexuality

Organizational effects

Early effects of sex hormones which have lifelong irreversible effects on behavior

Ontogeny for sexual orientation: CAH

(Congenital adrenal hyperplasia) - condition that caused abnormally high levels of androgens (male hormones) beginning early in fetal development. Girls with CAH and girls whose mothers took miscarriage medication are often born with virilized (somewhat masculine) genitalia - the degree of genital virilization in girls with CAH does not appear to be related to behavior

Are men choosier compared to most male mammals?

Men are choosier compared to most male mammals

Who's more competitive (men or women)?

Men are more competitive (Bateman Thrivers Theory)

What indicators of investment capacity in women do men prefer?

Men prefer: physically attractive, youthful partners who have low waist-hip ratios

What mating system characterizes humans?

Normally, humans are polygynous. However, if the OR is an equal ratio of men to women, we should observe a monogynous mating system

What is Adult Gender Identity Disorder

Person's sense of being male or female changes or becomes conflicted as an adult. They can experience homosexual transsexualism or antogynephilic transsexualism. Transsexualism or gender nonconformity

How is CAH related to childhood toy preferences, childhood play patterns, and sexual oriented in women?

Prenatal exposure to hormones is the basis for the normally seen between boys and girls in toy and baby-tending preferences

Bruce and Brian Reimer. What did it prove?

Proved that socialization determines gender identity - removing a boy's testes and treating him like a female wouldn't simply make him a female. Early development plays an important role in later gender identity

Bateman-Thrivers Theory:

Selection favors competition among males for females (the limiting resource) so that they can increase their fitness

What psychological sex differences do we see in humans?

Sexual orientation, interest in visual stimuli, interest in casual sex, childhood play, job interest (people vs things), physical aggression

Ontogeny for sexual orientation: Animal studies

Study caused same sex partner preference in female zebra inches by manipulation sex hormone levels in eggs. And early manipulation of hormone levels in both male and female rats affects adult sex partner preferences - suggests that sex hormone signaling affects sexual orientation in humans, as well

Ontogeny for sexual orientation: The perirhinal cortex and INAH-3

Study found the INAH-3 to be approximately 2-3 times as large in heterosexual men as in women and homosexual men (difference too small-statistically insignificant for homo men). INAH-3 appears to be related to sexual motivation, but it is far from clear whether differences in the size or structure of this region directly results in differences in sexual orientation

Sociosexuality

The individual difference in willingness to engage in sexual activity outside of a committed relationship.

What do men gain from mixed reproductive strategies?

The mixed reproductive strategy would allow a male to have one fertile partner and invest in her offspring, but also commit just enough resources to gain reproductive access to a number of other women

What do women gain from mixed reproductive strategies?

The mixed reproductive strategy would allow women to recruit genes and investment separately, choosing the best source of each

What is gender?

The socially constructed role and behaviors a culture considers appropriate for men and women

Red Queen Hypothesis relation to the importance of physical attractiveness

We evolved to view signs of consistent good health as attractive, because that means they're more likely to be able to fight parasites (health, vigor, symmetry). The need to create new immune systems to fight off parasites (parasite and hot co-evolution)

Who's choosier (men or women)?

Women are choosier

Are women more competitive compared to most female mammals?

Women are more competitive compared to most female mammals