Notes for Exam 3
Notes for Exam 3 Bios 373
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This 11 page Study Guide was uploaded by Cara Cahalan on Thursday April 7, 2016. The Study Guide belongs to Bios 373 at University of Nebraska Lincoln taught by Dr. Leger in Fall 2016. Since its upload, it has received 32 views. For similar materials see BIOPSYCHOLOGY in Biological Sciences at University of Nebraska Lincoln.
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Date Created: 04/07/16
Section 3 Study Guide: Focus on 15!! (16 and 17) Day 15 (3/10): Beyond Pink and Blue Lecture: Introduction As Nature Made Him, 2 twin boys, circumcised, one botched so parents had sex change operation (change to girl) John Money’s hypothesis: gender identity is due to postnatal socialization Competing hypothesis: gender identity is due to prenatal hormones Developmental Dominoes Male development o SRY gene (on Ychromosome) Produced HY antigen, a protein o Primordial gonads (undifferentiated) If HY antigen is present, develop into testes, induces gene expression o Testes produce Testosterone and dihydrotestosterone Develops male internal reproductive organs (Wolffian system) Penis and scrotum develop from “genital tubercle” (undifferentiated tissue) hormone that interacts with it (testosterone) influences its development/gene expression (testes) Masculinized brain structure Mullerianinhibiting substance Blocks development of female reproductive tract (Mullerian system) We all begin with both systems Female development o Females lack Ychromosome No SRY gene, no HY antigen o Primordial gonads develop into ovaries (instead of testes) o Lacking testes… No Mullerianinhibiting substance female reproductive tract develops Little testosterone, therefore… Wolffian system regresses, clitoris and labia develop from genital tubercle Feminized brain structure Organizational Effects of Hormones Gonadal steroid hormones o Organizational effects: longlasting anatomical/physiological forms brought about by exposure to a hormone during a sensitive period o Estrogens: estradiol and others Androgens: testosterone, dihydrotestosterone, and others o These two groups are NOT opposites Normal situations o Testosterone present develop the male syndrome* o Testosterone absent develop the female syndrome* o * Syndrome: includes external genitalia, internal reproductive tract, brain and behavior Three routes to masculinity o Direct testosterone route T + receptor interacts with DNA, influences gene expression (proteins produced that would not have otherwise) Most common outside the brain o Indirect testosterone route Testosterone enters cells and is converted to estradiol by aromatase (enzyme) influences gene expression masculinizing effect Most common in brain o Direct estradiol route Estradiol + receptor enters cell, influences gene expression masculinizing effect (indirect, rare) Chromosomal females (XX) will develop the male syndrome if given larger doses of estradiol Why? The defense against E is overwhelmed What is this defense? Alphafeto protein Binds to the outside of cells, but not inside to block estradiol entry into cell No effect on testosterone, present in males No masculinization by estradiol (females have no testosterone either) Summarizing 3 routes to masculinity: Males Females Direct T Yes (body) No Indirect T Yes (brain) No Direct E No (AFP) No (AFP) Organizational Disorders Afflicting chromosomal males: XY chromosome physically presenting as female o Androgen insensitivity syndrome due to defective testosterone receptors o Testes, yes. Ovaries, no. Why? SRY is present: primordial gonads become testes o No internal reproductive organs of either sex. Why? No response to testosterone so Wolffian system regresses Mullerianinhibiting substance causes Mullerian system to regress o External phenotype: female Afflicting chromosomal females: XX o Congenital adrenal hyperplasic (CAH) adrenal glands overproduce androgens o Ovaries, yes. Testes, no. Why? No SRY gene, so primordial gonads become ovaries o Female internal reproductive tract. Why? No testes, so no Mullerianinhibiting substance o Phenotype: masculinized external genitalia, brain, behavior Severity is highly variable Readings: Hormones influence reproduction: o Organizational hormones influence developmental patterns early in life, permanent o Activating later in life, temporary Sex hormones (steroid family) produced by the gonads (maletestes, female ovaries). Both sexes have both androgens and estrogens o Androgens: testosterone, dihydrotestosterone, and others o Estrogens: estradiol, others o Progestins: progesterone, more common in females Sensitive periods developing organism vulnerable to environmental conditions o Different parts of organism has different sensitive periods o Brain differentiates much later than genitals Example: new born rats o Sensitive period shortly after birth (1 week) o Male phenotype will develop whenever testosterone is present o Copulatory behavior exhibited in adulthood: after male stimulation, females will exhibit lordosis (copulatory posture) o Rat example: Row Chromosomal Sex Surgical Procedure Hormone treatment Adult Sexual Behavior 1 Male Castration (at birthNone Female 2 Male Castration (at 14 None Male days) 3 Male Castration (at birth)Testosterone (days 1 Male 7) 4 Female Ovariectomy (at None Female birth) 5 Female None Testosterone (days 1 Male 7) Female Ovariectomy (at Testosterone (days 1 Male 6 birth) 7) 7 Female Ovariectomy (at Testosterone (after Female birth) day 7) 8 Female None Large dose of Male estradiol (days 17) In rhesus monkey’s sensitive period for sexual differentiation of the brain occurs after birth Features of phenotype organized into male and female patterns: o Genital traits o Neural anatomy and physiology sexual differentiation in humans occurs in 3 trimester, due to receptors binding testosterone or estrogen molecules o Sexual orientation may be due to differences in prenatal hormone exposure o Other traits: Cessation of bone growth retarded when testosterone is present boys grow later Muscular strength Differences in kidney, muscle, and other tissues Shows that aspects of phenotype can develop independently of one another due to differences in sensitive periods Day 16 (3/15): The Fire Down Below: Activating Effects of Hormones Prelude: activating effects last time. Permanent effects due to hormonal status during sensitive period o Activating effects are temporary changes brought about by hormones. o An analogy: Organizational electrician installing wiring and switches Activating flip on light switch later o Activation won’t work unless organizational has been done. Organization can’t turn on the light without activation Lecture: Terms of Endearment Attractively opposite sex shows interest in you Proceptivity you show interest in the opposite sex Receptivity you willingly engage in sexual intercourse Female Sexual Motivation in not nonhuman mammals Motivation is activated by…. Estradiol only: rhesus monkey Estradiol + progesterone: rats Both lead to estrus (heat) temporary intense period of sexual motivation What about women? Background: Ovarian cycle hormones Estradiolproceptivity hypothesis: o Animal research: estradiol is always important Either alone, or with progesterone o Human research estradiol peaks near ovulation o Therefore: estradiol increases women’s proceptivity, increasing chances of conceptions o But, humans don’t have estrus Hormone action depends on: 1. Amount of hormone 2. Abundance of hormone receptors Receptor density differs among various organs and tissues If brain has few estradiol receptors little behavioral change even if the hormone is abundant Reproductive organs (with many receptors) can still have hormone induced changes o Just because estradiol is present don’t mean behavior will be affected by it o Ex. Enough testosterone and little beard growth Estradiolattractively hypothesis estradiol may make women more attractive to men in nonhuman primates (odor) o Men make more advances to more attractive women o If women accept advances at a certain rate than intercourse rates will go up, effect attractively instead of proceptivity Evidence: o Sex activity research: supports estradiolproceptivity hypothesis, no support for estradiolattractively. Initiate intercourse: menevenly, women most at ovulatory than follicular o Ovariectomy patients: selfreported “interest in sex”, support proceptivity. No decrease in intercourse rate (against attractively) Contextual hypothesis: o Hormones don’t matter, context does o Ex. Stress, desire for pregnancy, duration of abstinence, menstrual status and day of week Conclusions: o Estradiol probably increases women’s proceptivity a little, but not attractively o Contextual variables probably much more important than any hormone Male Sexual Motivation Testosterone and proceptivity in men o Individual differences in average T: no correlation with proceptivity difference, receptor density diff o Up’s and down’s in T in individual over time (proceptivity is increase with T increase) Lacking testosterone: Kallman’s syndrome o Males, organized properly prenatally, but no testosterone production after due to problem in hypothalamus o Appearance: prepubescence boy long after puberty should have occurs o Treatment: doses of testosterone, no interest in sex Ups and downs of T o Seasonal change: highest when day length decreases most rapidly o Erotic stimulation: sexy movies, sexual activity or its anticipation o Success: sports, graduation o Stress: decreases T Sex, lies and advertising: species differences in sexuality Intercourse rates: o Feast or famine species: gorillas and cats o Slow but steady species: titi monkeys, humans Relation to mating system o Feast or fame: 95% of all mammals, polygyny o Slow but steady: monogamous Ovulation o Conspicuous ovulation (sexual advertisement), common in feast or famine species Example: Baboon females sexual swelling leads to malemale competition for mating o Inconspicuous ovulation (concealed ovulation), common in slow but steady Fertility not apparent, so sex is periodic, keeps male around 1 female, male invests in offspring Conclusions Sexual motivation heavily dependent on hormones in some species, but not in others Human: sexual motivation increase in hormones in men more than women Nonhormonal sexual motivation in women may function to induce monogamous mating in men Readings: Why is sexual intercourse done in so many different ways? o Physiology of ovulation: Spontaneous ovulators hormonal changes in the female lead to ovulation Induced ovulators release eggs only after copulation o Preparing the uterus for implantation of the fertilized ova Overt sexual selection choices made prior to mating Cryptic sexual selection females choose among males even after copulation has taken place Day 17 (3/17): The Monogamy Myth Lecture: Type there is no question 16.5, the correct answer to 17.5 is C Naturalistic Fallacy Fallacy is to draw moral lessons from nature Main mating systems Terminology Males Females Relationship Monogamy 1 1 Longterm Polygyny (polygamy) 1 2+ Longterm Polyandry 2+ 1 Longterm Polygynandry 2+ 2+ Longterm Promiscuity Temporary o No clear categories: Most individuals are monogamous, but… A few males have a second mate slightly polygynous A few females have a second mate slightly polyandrous Points on a continuum Ecology of mating systems o Resource and mate distribution (Clumped or dispersed) o Clumped, monopolization is possible polygyny (usually) and polyandry o Dispersed, monogamy is likely (promotes equality between the sexes in appearance) Emperor tamarin both males and females have mustaches Mythical Monogamy Pure monogamy has never been found at the species level, but some come close (i.e. Trumpeter swans) Serial monogamy: a series of monogamous relationships o Man with multiple wives: Man socially monogamous, but reproductively polygynous o Johnny Carter four wives but only reproduced with the first socially and reproductively monogamous More than one mate at the same time: simultaneous polygyny or polyandry o Would become socially polygyny or polyandry, but could still be reproductively monogamous Biological markers of mating systems Mating system selects for traits that lead to reproductive success in that system o Like geneculture coevolution o Different mating systems select for different traits o Current traits reveal previous selection 1. Body Size ratios Monogamy Male = female Polygyny Males larger Polyandry Females larger Promiscuity Males larger o Size and fighting ability o To the victors do the reproductive spoils 2. Maturation rates Monogamy Male = female Polygyny Males later Polyandry Females later Promiscuity Males later o Later maturation rates because growing a larger body stalls maturation rate 3. Reproductive Variance Monogamy Males and females equally variable Polygyny Males more variable Polyandry Females more variable Promiscuity Males more variable Summary: biological markers o Reflect past selection conditions on males and females o Good indicator of what mating system the species used during its evolution o Monogamy promotes sexual equality o Polygamy promote sex differences But in opposite directions in polygyny and polyandry Human mating systems Biological markers o Men, on average, are about 10% taller, 40% heavier, slower to mature, greater reproductive variance o Due to women’s shorter reproductive window Other evidence o Anthropological Monogamy is universal, many societies also allow simultaneous polygyny But most individuals are monogamous Simultaneous polyandry is extremely rare (residents of Himalayas) Serial monogamy is common (more common in men) Promiscuity and adultery occur in all known societies, although often rare o Sociological data (U.S. data on serial monogamy): Remarriage after divorce or spouse’s death: more common in men than in women Remarriage that yields children: more common in men than in women Conclusions o Humans have been mostly monogamous, with a dash more polygyny than polyandry Readings: Polygyny more unmated males than unmated females, males exclude others in three ways: o Resource defense polygyny males acquire and defend that resources against other males o Female defense polygyny grouping of females, in mammals (lions forming prides) o Male dominance polygyny differences in success due to dominance differences, dominant gets mates Polygynandry males and females have multiple mates, polygyny and polyandry simultaneously (lots of conflict) Polygyny threshold when it is advantageous for a female to mate polygynously rather than monogamously Surreptitious matings female mimicry by males, males get close enough to females to mate (fish) Forced matings females exert strong mate choice, rape Day 18 (3/29): The Pretty Woman Story Lecture: Evolutionary Psychology of Mate Choice Intro to evolutionary psychology: we are descended from our ancestors who were adapted to their conditions Evolutionary psychology of mate choice o Our ancestors chose their mates “wisely” o The attributes of mates attractive today are the ones that led to reproductive success in our ancestors o These attributes are predictive of: Direct benefits: resources/services for female/offspring Good genes: genetic quality of offspring (i.e. symmetry of males) What about people? Sex differences in mate choice o Mate choice criteria often differ between men and women o Social science perspective: differences due to socialization (i.e. movies) o Evolutionary psych perspective: differences have evolved (i.e. body size differences) o Evidence? Spouse preference men and women agree that sense of humor, intelligent, cooperative, and considerate are all important Social scientists: see no difference! Evolutionary psychologist: no big deal Reproductively relevant criteria: after general criteria, we get differences: body proportions, facial attractiveness, income/resources, and status (differences in relative importance) What men find attractive, and why o What: o Why: Facial features (smooth skin, Indicators of youthful maturity symmetry) (high reproductive potential) Body proportions: waisttohip ratio (~70% is ideal), breast enlargement What females find attractive, and why o What: o Why: Shoulderstowaist ratio Ability to protect Resources/status Resources and status Gifts, time, attention Generosity What women and men find attractive: indications of health and vigor (facial symmetry) Sex differences revisited: o Relative importance of feature, not different features Women are not oblivious to male physique Men are not oblivious to female resources o Conclusions: Socialized or evolved? Details, socialized (i.e. clothing, hair styles) Basics, evolved (universal preferences for body proportions and facial symmetry) Movies don’t cause our mate preference choices, they use our evolved preferences o Positive Assortative Marriage (PAM) PAM: married couples resemble each other more than is expected by chance Statistics: positive correlations between wives and husbands on all sorts of traits: o Physical (height, weight), physiological (blood pressure, startle response), psychological (IQ, personality traits) Married couples, on average, are as similar as oppositesex first cousins How does PAM happen? o 3 hypotheses have been proposed: 1. Phenotype matching hypothesis: While young, learn the characteristics of one’s opposite sex parent or siblings When adult, search for the best match (similarity is attractive) 2. “Go for the best” hypothesis If males and females agree on what is best, phenotypic similarity results Pigeon breed example: all pigeon breeds thinks certain breed is most (or least) attractive Similarity is a byproduct of everyone going for the same thing 3. “Love the one you’re with” hypothesis PAMPromotingPlaces: Any setting in which similar reproductiveage people meet “Concentrates” similar genes (similarity is byproduct) Example: volleyball player, tall people marry other tall people Conclusions: o Phenotype matching? Probably not (similarity is not the goal) o Readings: Evolutionary psychology operations performed by the brain, which has been built by the influence of numerous genes that have been carefully scrutinized by natural selection Perceptual valences positive or negative assessments of the things we perceive Potential mates that we find attract are those that led reproductive success in our ancestors, and which tend to produce reproductive success today Species make choices about perspective mates, associated with characteristics of reproductive success either in the form of good genes or direct benefits Inbreeding depression production of fewer offspring or offspring with more effects than would result from matings of unrelated individuals o Day 19 (3/31): Mommy’s Baby Daddy’s maybe o Lecture: o What is Parental Investment (PI)? PI anything parents do or provide that increases the odds of their offspring survival and reproducing o Ex. Feeding, protection care, teaching o Sex Differences in PI Usually, mostly or exclusively by females (sometimes, mostly or exclusively male), sometimes equal Relation to mating system o Monogamy: biparental care favored (sparse food resources or intense predation on young) Keeps both parents investing o Polygamy: uniparental care allowed (food supply, predation pressure) Polygyny PI mostly by female. Polyandry PI mostly by male o Promiscuity: uniparental care allowed No association after mating, so female does it all o Parenting: another “biological marker” of mating systems When is PI adaptive? o Your PI is adaptive (for parents) only if: 1. Offspring does better with your help (due to ecology), and 2. offspring are genetically your own (due to probability of parentage) o The adult providing the PI is not necessarily the biological parent of the offspring This may be voluntary (adoptions) or involuntary o Cuckoldry adult tricked into providing PI for another’s offspring Two routes to cuckoldry: brood parasitism, “extrapairbond” fertilization Cuckoldry and the monogamous male: select for parenting, only adaptive is offspring is genetically yours Cuckoldry defense: mate guarding (barn swallow) and mate desertion (mountain bluebird) o Cuckoldry Defense in Men Sexual jealousy: o Men extreme concern about sexual activities of mate o Leading motive for: homicide among men, spousal abuse and homicide, and divorce by men Phenotypic similarity to offspring: two studies (Does child look like me?) o 1. 25 moms, 34 months postpartum: 21: baby resembles husband, 2: husband’s father, 2: mother o 2. 20 moms, 15 minutes postpartum 16: resemble husband, 4: mother o Terminating Parental Investment Prenatal termination: spontaneous abortion (miscarriage) due to maternal stress or fetal disorders o “Strangermale” effect in rodents: male removed early in pregnancy females resorbs fetus. Later in pregnancy spontaneous abortion due to infanticide by male strangers Cost cutting for females Postnatal termination: infanticide or abandonment o Terminating PI can be adaptive (in certain conditions) When is infanticide adaptive? o Maternal age infanticide is more common in younger mothers If environment is bad now, younger mothers have higher chance of producing future offspring Infanticide can protect residual reproductive potential o Parental stress Gerbil tails: young gerbils will kill young under stressful conditions because of their ability to potentially produce more in the future Human infanticide most common in stressed households: low income, single parent, lacking other family supports o Infant condition Physically malformed infants cleft palate Socially unresponsive often due to sensory deficits Neurological disorders “criduchat” syndrome o Conclusions: Discriminative parental solicitude unequal investments in offspring based on offspring traits If conditions are favorable invest If not walk/fly/swim away (try again later) o Readings: Hypothesis for changes in parental investment over time: o Expected benefits parents asses the number of quality of offspring and allocate resources accordingly, future projection based on current information o Previous expenditures current investment driven by amount of investment that individuals previously made Concorde fallacy current investment decisions based on previous expenditures can be risky! Parentoffspring conflict parent’s and offspring’s interests do not coincide (i.e. weaning) Lactational amenorrhea occurs when mammals secrete milk, chances of ovulation and fertility are reduced Hormonal changes due to lactation and energetic drains of lactation increase time between pregnancies Residual reproductive potential (RRP) about the future, time remaining is what matters o Day 20 (4/5): The Evolution of Love o Lecture: o The Behavior and Ecology of Love What is love? o Strong affection for another arising out of kinship or personal ties o Attraction based on sexual desire o Love is a private state, but gives rise to observable behaviors and physiological conditions Others: hunger, fear, memory The behavior of love o Titi monkeys and squirrel monkey. Pairs formed in the lab o After living together for months, one partner was removed for an hour and then reunited o What happened? Titi monkeys: Squirrel monkeys: When separated: When separated: no agitation, loud calling, change in behavior or cortisol surge cortisol When reunited: intense When reunited: no big cuddling, close deal following o Summary: Signs of stress occur in some species when separated from the mate Signs of “comfort” when with the mate Love? Why some species and not others? The ecology of love o Monogamy and biparental care (resources and predation) o About 3% of mammalian species are monogamous o “Loving” species are all monogamous o Might “love” facilitate parental teamwork? Brains and Bonding Experiment: new couples formed in lab and left together for 24 hours. Results: o Prairie voles: cuddling/grooming for 6+ hours, then sex, partner preference o Meadow/montane voles: no cuddling, sex maybe (if female is in estrus), no partner preference What’s sex got to do with it? o Prairie voles: cuddling without sex. Partner preference? Yes, but it takes longer o Sex triggers a surge of vasopressin in males and oxytocin in females o Inject vasopressin (males) or oxytocin (females): Partner preference occurs without sex, in only an hour o Inject antagonists to vasopressin or oxytocin Blocks partner preference (even with sex) o What about these hormones in the other species? Injections are ineffective. Why? Species differences in receptor densities OTR= oxytocin receptor V1a= vasopressin receptor More receptors in monogamous species Gene manipulations: insert prairie vole V1a gene into male mice partner preference! Summary: o Monogamy: o Promiscuity: Ne estrus Estrus Strong bonding No bonding High response to O and V Low response to O and V Peptides and people o Women: oxytocin increases during sexual arousal and while nursing o Men: vasopressin increases during sexual arousal o Both sexes: oxytocin increases with parental experience Giving oxytocin (nasal spray): increased trust and lower reaction to fearful faces The Evolutionary Origins of Love “Love” is patchily distributed in mammals, occurs in monogamous species (rodents, primates, antelopes) o Love may be derived from something that it is widespread in mammals (monogamy) o How about motheroffspring bonding?alpha Separation distress, reunion closeness and relief, but is all maternal love the same? NO Motherly love and mating systems o Monogamy (prairie vole): o Promiscuity (meadow voles): Oxytocin receptors always Oxytocin receptors birth present through weaning only Virgin “mothers” Virgin “murderers” Postweaning: tolerance of Postweaning intolerance of offspring offspring Fatherly love and mating systems o Monogamy: o Promiscuity: Vasopressin receptors abundant Vasopressin receptors always and always present sparse Virgin “fathers” No parental care at any time Summarizing: Parental love Mothers Fathers Monoga Always on Always on my Promisc Temporarily on Never on uity Conclusions: Monogamy: biparental care, and a different form of maternal care Males of monogamous species show parental behavior similar to that of females “Love” among adults may be an extension of evolved parental psychology Readings: Anterior cingulate cortex stimulated when looking at pictures of loved ones, associated with emotional responses Love comes from motheroffspring bond Evolution of love: began with temporary oxytocin/offspring care system (monogamous leave system on)
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