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Biology Ch.12

by: Monique Magpayo

Biology Ch.12 Biol360

Monique Magpayo
Cal State Fullerton
GPA 3.52

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Chapter 12 Lecture and Book Notes
Biology of Human Sex
Maryanne Menvielle
Class Notes
Biology Book Notes, Lecture Notes Chapter 12
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This 8 page Class Notes was uploaded by Monique Magpayo on Tuesday March 29, 2016. The Class Notes belongs to Biol360 at California State University - Fullerton taught by Maryanne Menvielle in Spring 2016. Since its upload, it has received 13 views. For similar materials see Biology of Human Sex in Biology at California State University - Fullerton.

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Date Created: 03/29/16
CH 12 Book NOTES and terms  SEXUAL ORIENTATION: is the dimension of personality that describes the balance of our sexual attraction to the two sexes. (the direction of a persons sexual feelings: sexual attraction towards persons of the opposite sex, the same sex, or both sexes.  HETEROSEXUALITY: sexual attraction only or predominantly to persons of the other sex  HOMOSEXUALITY: sexual attraction only or predominantly to persons of one’s own sex  BISEXUALITY: sexual attraction to both sexes  The colloquial terms STRAIGHT and GAY have replaced the “heterosexual” and “homosexual” terms  LESBIAN- homosexual applied to women only  KINSEY SCALE: a 7 point scale of sexual orientation devised by Alfred Kinsey  The Kinsey scale is less used today by researchers than in the past.  GENDER-VARIANT: atypical in gender characteristics  GAYDAR- the ability to recognize gay people on the basis of unconscious behaviors, voice quality, gait, and so on.  GYNEPHILIC: sexually attracted to women  ANDROPHILLIC: sexually attracted to men  MEDIAL PREOPTIC AREA: a region of the hypothalamus involved in the regulation of sexual behaviors typically shown by males  INAH3: (third interstitial nucleus of the anterior hypothalamus) a neuronal cell group in the hypothalamus that differs in size between men and women and between gay and straight men  THE HYPOTHALAMUS AND MALE SEXUAL ORIENTATION: a cell group known as INAH3 lies within the medial preoptic area of the hypothalamus, a region concerned with MALE-TYPICAL sexual behavior  Two autopsy studies found that INAH3 is smaller in women and gay men than in straight men; but they did not agree on the magnitude of the difference  COME OUT OF THE CLOSER: (or “come out”) Reveal a previously concealed identity, such as being gay  BATHHOUSE: a facility, usually in the form of a private club, used for casual sex between men  BUTCH: masculine acting, often used to describe certain lesbians  FEMME: feminine- acting, often used to describe certain lesbians or bisexual women.  BEARS: in gay slang, a burly gay man with plenty of body hair; more generally, a member of a gay male subculture that rejects many of the prevailing standards of gay male attractiveness and behavior.  GAY BASHING: hate crimes against gay people. Sometimes includes verbal abuse as well as physical violence  IMPLICIT ASSOCIATION TEST: a psychological test that is intended to reveal unconscious or unstated preferences  HOMOPHOBIA: prejudice against homosexuality or gay people  FEMIPHOBIA: prejudice against femininity in males.  BIPHOBIA: prejudice against bisexuals o SUMMARY  SEXUAL ORIENTATION defines how a persons disposition to experience sexual attraction varies with the sex of their potential partners  It can be represented on a 5- or 7-point scale from heterosexual  Though varying bisexuality, to homosexual  Only 2-3% of population is homosexual. With men being more common than women  Lesbian and gay men, although diverse, tend to be sex-atypical n their self-described masculinity-femininity, in cognitive and personality traits, and in occupational interests.  This gender nonconformity is evident in children who later become gay adults.  A variety of THEORIES have been put forward to explain how sexual orientation develops.  ACCORING TO FREUDIAN PSYCHOANALYTIC THEORY: Heterosexuality emerges from a complex sequence of stages of PSYCHOSEXUAL development  The DISRUPTION of several of these stages may lead to homosexuality  ACCORDING TO SOCIALIZATION THEORIES: a child’s ultimate sexual orientation is molded by innumerable rewards and punishments given by parents and others  ACCORDING TO BIOLOGICAL THEORIES,: sexual orientation is affected by factors such as prenatal hormone levels, which are thought to influence the organization of brain systems responsible for sexual attraction.  GENES also influence sexual orientation, especially in men, but the specific genes involved have not yet been identified  The MODERN GAY RIGHTS movement began in 19 century GERMANY and spread to the US after SECOND WORLD WAR  A key event was the STONEWALL REBELLION, a riot in NYC in 1969 that led to the politicization of the gay community  THE AIDS EPIDEMIC, which began around 1980, devastated gay male communities.  It was also the spur to more effective political action and to greater openness on the part of gay people  The rapid advances made by lesbian and gay men have made them the focus of a cultural conflict between conservative and progressive forces in American society.  The same conflict is playing itself out worldwide,  In some countries, gay people have gained greater acceptance than in the US while others they are more severely stigmatized  PRE-GAY CHILDREN who are markedly gender nonconformist typically experience taunting, abuse, or efforts to normalize them.  For GAY PEOPLE, PSYCHOLOGICAL DEVELOPMENT is pa process of “coming out”  The “COMING OUT” PROCESS involves several stages:  SELF REALIZATION and SELF ACCEPTANCE  DISCLOSURE TO OTHERS  JOINING THE GAY COMMUNITY  And INTEGRATING ONE’S HOMOSEXUALITY WITH OTHER ASPECTS OF ONE’S CULTURAL IDENTITY  Gay sex and gay relationships are quite similar to their heterosexual counterparts  Gay men tend to be more sexually adventurous and have more partners than lesbians or heterosexual people, but monogamous gay relationships are also common  There is diversity within the gay and lesbian communities. Some lesbian identify as “butch” and some other “femme”  Some gay men have preferred sex roles as “tops” or “bottoms” but many are “ versatile “  With the gay male community there is a leather/ BDSM subculture as well as “bear” community that rejects the prevalent gay standards of male beauty  Many lesbian and some gay men are parents, either from earlier heterosexual relationships or as a result of a variety of reproductive techniques that are open to gay couples  The children of gay parents generally thrive: they may experience some taunting in school, but they are as well adjusted as the children of straight parents, and they tend to be more tolerant and empathetic  Anti-gay attitudes and behaviors (homophobia) have multiple roots  HOMOPHOBIA ROOTS:  CULTURAL INDOCTRINATION  An AVERSION to the idea of engaging in sex with a SAME SEX PARTNER  An IMAGE of HOMOSEXUALITY as a TRANSGRESSION OF SOCIAL RULES,  Or a DEFENSE MECHANISM against one’s own real or feared homosexual tendencies  Overcoming homophobia depends primarily on personal interactions at a grassroots level  Bisexual men and women have the advantage of a wider potential range of sexual experience , but they also face social stigma (biphobia)  They may be mischaracterized as closeted gay people, as oversexed, as spreaders of AIDS, or as inconsistent partners.  BISEXUALS have attempted to forge a social and political identity that is at least partially separate from that of gay people LECTURE NOTES  4 MAIN TOPICS: intro to orientation, reasons for studying orientation, biological studies of orientation, other models of the development of ones orientation  SEXUAL ORIENTATION- DEFINITIONS  Sexual orientation-A persons erotic and emotional orientation. Heterosexual- straight  Homosexual-gay/lesbian  Bisexual towards both men and women  SURVEYS are usually used to collect info to how many people are gay, straight, or bi -It is difficult to determine How one views themselves and their gender identity affects their answer  Definitions used. Are they homo if Exclusive same-gender experiences or if some same gender experiences  Or is it applied to any type of attraction with or without action  The honesty of the participant may alter their answer towards the survey as well  10% of men and women had at least one same-gender sexual experience in adulthood  4% of men and women experience same gender attraction  Only 2% of men and 1% of women would describe themselves as EXCLUSIVELY HOMOSEXUAL  Many argue that bisexuality does not exist, they think these are people who have not fully embraced their homosexuality  ALFRED KINSEY had a different view on orientation and developed a continuum of sexuality with a range from 0-6  0- exclusively heterosexual  1-mostly heterosexual with incidental homosexual experience (like a shared kiss)  2- heterosexual with substantial homosexual experience  3- equal heterosexual and homosexual experience  4- homosexual with substantial heterosexual experience  5- homosexual with incidental heterosexual experience  6- exclusive homosexual  In order to explain the development of one’s orientation  VARIOUS IDEAS: biological or psychodynamic o BIOLOGICAL:  Genetic factors  Prenatal exposure to androgens  Birth orders o PSYCHODYNAMIC  Freud’s Psychoanalytic model  Socialization  RESEARCHING ORIENTATION :  Argument of NURTURE vs. NATURE  Is one sexual orientation something they are born with (NATURE)  Or is it the way they were raised or impact of life experiences (NURTURE)  Researching orientation also makes us ask what is NATURAL vs. NORMAL  SOME SAY since it is not practiced by all then it is not NORMAL  Homosexuality is considered UNNATURAL  The other side argues that what is NATURAL IS NOT ALWAYS THE NORM in society. Many of our sexual behaviors are influenced by society and cultural standards  They also point to observation of same sex behaviors and pairings in many different species such as sheep, dolphins, penguins, and primates  Many people are not comfortable with the results of these research  Scientific findings do not always lead to social enlightenment  If it is proved scientific, a fear would be to “cure” homosexuality BIOLOGICAL  Exploring why homosexuality runs in families  One of the first steps to determine if there is a genetic cause ((intellegience, autism, orientation)) would be to Conduct research with TWIN STUDIES  TWIN STUDIES are very insightful to the influence of genes on a particular trait  TWIN STUDIES utilize pairs of monozygotic and dizygotic twins  MONOZYGOTIC: are identical twins since they possess the same DNA formed from a single zygote or fertilized egg  DIZYGOTIC TWINS: occur when two separate eggs are fertilized by separate sperm that occur from a single pregnancy. FRATERNAL TWINS ARE NO MORE GENETICALLY RELATED TO OTHER THAN ANY OTHER SIBLINGS that occur during separate pregnancies  The only difference is fertilization and development occurred with FRATERNAL twins at the same time  TWIN STUDIES Look at CORCORDANCE RATE- which is the rate at which both twins exhibit a particular trait and compares that rate to how often it occurs in monozygotic twins vs dizygotic twins  This allows researchers to evaluate the influence of genes have on the trait as opposed to environmental influences  Since MONOZYGOTIC and DIZYGOTIC TWINS both develop in utero together and have many of the same life experiences, the real differences between the concordance rates of these groups can be attributed to the influence of genes  For example: if a trait is entirely genetic, you would expect the CONCORDANCE RATE to be 100% in monozygotic twins  ENTIRELY GENETIC= 100% concordance rate of monozygotic twins  While the percentage of DIZYGOTIC twins, who both share the same trait, would be significantly less and more likely to be at the same rate as non twin siblings  If there is NO GENETIC INFLUENCE on a trait then you will expect the CONCORDANCE RATE on monozygotic and dizygotic twins to be about the same  If the rate is MULTI-FACTORAL (GENETIC and FACTORS involved) = % of concordance of monozygotic twin is higher than dizygotic twins and it will not be 100%  NO GENETIC INFLUENCE= CONCORDANCE rate of monozygotic and dizygotic twins the same  Intelligence is a gene , but environmental factors such as nutrition and educational experiences would impact one’s cognitive abilities  TWIN STUDIES and ORIENTATION  BAILY & PILLARD (1991) found 52% concordance rate of male identical twins and 22% in male fraternal twins  Meaning 52% of the time, when one identical twin identifies as homosexual , the other one did as well  A follow up study BAILY & et al., (1993) found 48% concordance rate in female identical twin and 16% of female fraternal twins  Other studies have found similar results such as KENLER AND KIRK  The conclusion that can be drawn from this data  CONCLUSION: Monozygotic (identical) twins are MORE LIKELY (higher concordance) to have the same orientation (gay or straight) than dizygotic twins  Suggesting that orientation is a MULTI-FACTORAL TRAIT that has some genetic component  But a single gay gene does not appear to exist  PRENATAL HORMONE HYPOTHESIS suggests that exposure or sensitivity to androgens affect orientation  The idea is EARLY EXPOSURE predisposes individual to become gynephilic or attracted to females  Support for this idea comes from animal studies where they expose androgens to rats during key developmental periods and then subsequentaly saw changes in their sexual preferences and interactions  We also know when female fetuses are exposed to androgens as in the case of CAH (CONGENITAL ADRENAL HYPERPLASIA) they exhibit a high range of same sex attraction and behaviors  On the opposite end, the hypothesis suggests that MALES that have been exposed to LOW LEVELS OF androgens during early development would express androphilic preferences or attraction to males  This would be similar to the preferences of females who were also exposed to lower levels of androgens  There is likely no constant levels of androgens that would determine the preferences since ones sensitivity towards the hormone varies  OTHER MARKERS OF ANDROGEN EXPOSURE o FINGER LENGTH RATION (D2:D4) comparing the length of the index finger (D2) to the ring finger (D4)  It is known the HIGHER EXPOSURE to ANDROGENS= LOWER D2:D4 ratio  This means the typical male’s index finger is shorter than ring finger  Women’s index finger (D2) is almost as long as ring finger (D4)  A study by McFADDEN in 2005 FOUND that less men have a ratio similar to straight men than straight women  RESULTS: Lesbians have a ration more similar to straight men than straight women o STUDYING THE STRUCTURAL DIFFERENCES IN THE BRAIN  INAH3 area of the hypothalamus is located in the MEDIAL PREOPTIC AREA which is found in front of the hypothalamus and is known to REGULATE male-typical sexuality  Studies of this area of the brain reveal that there is a SIZE DIFFERENCE between males and females and heterosexual males and homosexual males  The results of this studies show that INAH3 AREA IS SMALLER in gay men compared to straight men with the size being similar to a heterosexual female  There is no difference between gay men and straight women  One study used PET scans to detect brain activity in response to AND (ANDROSTADIEONE) which is a compound release by males in sweat and urine  Exposure to undetectable levels of AND show that the hypothalamus including the medial preoptic area were activated in people who were attracted to males  HYPOTHALAMUS ACTIVATED in heterosexual women and homosexual men  The same brain response was not seen in heterosexual men and lesbians indicating the compound did not trigger a response  OTHER studies used the female compound equivalent to AND showed opposite findings when exposed to compounds released by females o BIRTH ORDER  Observation: GAY men have more OLDER BROTHERS than straight men  POSSIBLE EXPLANATION: H-Y antigen hypothesis (a maternal immunological response to male embryos.  This immune response would occur since the Y chromosome produces proteins or antigens that are involved in the process of sexual differentiation  These proteins would be seen as foreign to the mother’s body which will trigger an immune response that would target the embryo  With each pregnancy, the immune response would intensify, affecting subsequent male embryos in a greater capacity  This immune response is thought to affect the development of the brain  EVERY male pregnancy causes a larger immune response which affects the brain development o PSYCHOANALYTIC  SIGMUND FREUD proposed that homosexuality was a DISRUPTION of “normal” psychosexual development. Basically homos were stuck in this phase and had to figure out their psychosexual development  No evidence supports this model o SOCIALIZATION  Sexual orientation has been attributed to socialization and early sexual experiences  No evidence supports this model  Suggests that events like molestation, rape, and consensual same sex relationships in same sex environments would lead to one becoming a homosexual   REFERENCES TO STUDIES NOT DISCUSSED IN THE TEXTBOOK  Bailey, J. Michael, & Pillard, Richard C. (1991) A genetic study of male sexual orientation. Archives of General Psychiatry, 48, 1089-1096.  Bailey, J. Michael et al. (1993). Heritable factors influence sexual orientation in women. Archives of General Psychiatry, 50, 217-223  Kendler, Kenneth S., et al. (2000) Sexual orientation in a U.S. national sample of twin and nontwin sibling pairs. American Journal of Psychiatry, 157, 1843-1846.  Kirk, K., et al (2000). Measurement models for sexual orientation in a community twin sample. Behavior Genetics, 30, 345-356.  McFadden, Dennis, et al. (2005). A reanalysis of five studies of sexual orientation and the relative length of the 2 and 4 fingers. (The 2D:4D ratio). Archives of Sexual Behavior, 34, 341-356.


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