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Lecture 11: Sexuality & Control of Female Sexuality • Control of Females & Female Sexuality Is ‘The Female Orgasm’ Adaptive? • Evolution of Patriarchy • Clitoridectomy The Behavioral Biology of Women - 2006 Female orgasm as non-adaptive • Females have low variance in reproductive success (RS) (Symons 1979; Gould 1991) Female orgasm as non-adaptive • Females have low variance in reproductive success (RS) • Variance in sexual behavior does not effect a woman’s RS (Symons 1979; Gould 1991) Female orgasm as non-adaptive Female orgasm as non-adaptive • Females have low variance in reproductive success (RS) • Variance in sexual behavior does not effect a woman’s RS • Female orgasm is a by-product of mammalian bi-sexual potential. Orgasm is possible because it is adaptive for males. • Females have low variance in reproductive success (RS) • Variance in sexual behavior does not effect a woman’s RS • Female orgasm is a by-product of mammalian bi-sexual potential. Orgasm is possible because it is adaptive for males. • Can’t be adaptive because it doesn’t always happen. (Symons 1979; Gould 1991) (Symons 1979; Gould 1991) 1 Problems with Non-adaptive Hypothesis Problems with Non-adaptive Hypothesis • Assumes that females in a natural state — unlike males — breed at or near their reproductive capacity, and that there is little room for natural selection to operate on females • Assumption that copulation serves no function other than insemination • Assumes that females in a natural state — unlike males — breed at or near their reproductive capacity, and that there is little room for natural selection to operate on females Blaffer-Hrdy, 1981 Adaptive Hypothesis: Intermittent Reinforcement • Female orgasm has been selected to be irregular • Increases likelihood of mating • Encourage Extra-Pair Copulations (EPC) • Non-human primates have orgasms Blaffer-Hrdy, 1979/1981; Diamond 1980 Is ‘The Female Orgasm’ Adaptive? Problem with debate: Assumes female orgasm = Female sexuality Blaffer-Hrdy, 1981 Intermittent Reinforcement • Female orgasm has been selected to be irregular • Increases likelihood of mating • Encourage Extra-Pair Copulations (EPC) • Little evidence that human females engaged in closely spaced repeated copulations with multiple males • Non-human primates have orgasms • But, not during intercourse Blaffer-Hrdy, 1979/1981; Diamond 1980 “It is difficult to see how expending time and energy pursuing the will-o-the wisp of sexual satiation, endlessly and fruitlessly attempting to make a bottomless cup run over, could conceivably contribute to a female’s reproductive success. On the contrary, insatiability would markedly interfere with the adaptively significant activities of food gathering and preparing and child care. Symons, “The Evolution of Human Sexuality,” 1979 2 Is female orgasm adaptive? Questions about female sexuality: (1) Is ‘the female orgasm’ adaptive? (2) Is the clitoris a product of natural selection? (3) Is female sexual response adaptive? • Capacity for orgasm may be a universal — although not universally realized (Masters & Johnson) but not necessarily from intercourse • Non-human primate females appear capable of orgasm (not during intercourse) • Orgasm probably not frequent in many cultures • Orgasm during intercourse occurs about 1/4 of the time in some studies of western women (should go to fixation if adaptive for intercourse) • Problems with adaptive argument • Probably does not qualify as a physiological adaptation per se Has the clitoris evolved through natural selection? Has the clitoris evolved through natural selection? • Function of the clitoris: transmits pleasure upon stimulation that may or may not culminate in orgasm. Has the clitoris evolved through natural selection? • Function of the clitoris: • • transmits pleasure upon stimulation that may or may not culminate in orgasm. The size and position of the clitoris shows variation between primate species In humans, the clitoris is sometimes removed as a way to control/remove female sexual pleasure. • Function of the clitoris: • transmits pleasure upon stimulation that may or may not culminate in orgasm. The size and position of the clitoris shows variation between primate species Is female sexual pleasure adaptive? • Does the potential for female sexual pleasure affect her behavior and ultimately her reproductive success? 3 Is female sexual pleasure adaptive? • Does the potential for female sexual pleasure affect her behavior and ultimately her reproductive success? > Increase the probability of seeking extra-pair copulations, which under some circumstances may lead to: _ _ Improved “genetic” quality of offspring Confusion of paternity and investment from more than one male Is female sexual pleasure adaptive? • Does the potential for female sexual pleasure effect her behavior and ultimately her reproductive success? > Increase the probability of seeking extra-pair copulations, which under some circumstances may lead to: _ _ Improved “genetic” quality of offspring Paternity confusion and investment from more than one male > Strengthen the duration of pair-bond with an investing male — influencing offspring survival Is female sexual pleasure adaptive? Orgasm & Sperm Retention • Does female arousability (or orgasm) increase the probability of conception? > Arousability facilitates copulation > Orgasm and sperm retention Baker & Bellis, 1993 Orgasm & Sperm Retention Female Orgasm and Male Ejaculation • 35% sperm ejected by female within 30 minutes • Sperm retention influenced by female orgasm • Orgasm more than 1 • minute before male ejaculation led to lowest level of sperm retention Sperm from one copulation hindered retention of sperm at next copulation up to 8 days Baker & Bellis, 1993 Baker & Bellis, 1993 4 Female Orgasm and Male Ejaculation • Timing isn’t right: More • • • Intercourse and oxytocin release • Intercourse alone causes release of oxytocin than 50% of female orgasms before male ejaculation Don’t know how much ejaculated, thus hard to measure flow-back accurately Small sample size, certain individuals over sampled Hasn’t been replicated • Oxytocin may increase sperm uptake Is female sexual pleasure adaptive? • Does female arousability (or orgasm) increase the probability of conception? > Arousability facilitates copulation > Orgasm and sperm retention >Evidence not good for role of orgasm in sperm retention >IS evidence for a role of intercourse in oxytocin release and sperm retention Female Sexual Adaptations: (1) Is ‘the female orgasm’ adaptive? No, Probably has not been selected for independently (2) Is the clitoris a product of natural selection? Yes, shows evidence of this. (3) Is female sexual response adaptive? Yes, there is evidence of this The Control of Female Sexuality “Why is there such interest in the sexuality of women rather than men? Yalman, 1963 Paternity Certainty “Why the emphasis on the bodily modesty of women, their seclusion, their chastity, their sexuality, their punishment, their protection, their control? In short, why the modesty code?” Antoun, 1968 5 Societies with Extreme Control of Female Sexuality • Development with stratification of society Control of Female Sexuality Europe after development of agriculture • Accumulated resources could be passed on Purdah China to male heirs. Thus, increased importance of Paternity Certainty Control of Female Sexuality: Medieval and Rennaisance Europe Chastity Belts 6 Modern Chastity Belts Foot Binding in China Foot Binding in China Foot Binding in China Foot Binding in China Foot Binding in China • Means of restricting female movement • Denotes upper class status (aren’t reliant on feet) 7 Foot Binding in China today? Manifestations in Western society? Manifestations in Western society? Purdah Institution related to control of women’s sexuality and the perseverance of family honor in Arab Muslim societies throughout the Near East • Most extreme in upper classes 8 Purdah Purdah Institution related to control of women’s sexuality and the perseverance of family honor in Arab Muslim societies throughout the Near East Institution related to control of women’s sexuality and the perseverance of family honor in Arab Muslim societies throughout the Near East • Most extreme in upper classes • Female modesty represents honor of the • Most extreme in upper classes • Female modesty represents honor of the family • Females are competing for high status males. • One patrilineage guarantees paternity certainty to another patrilineage. family • Females are competing for high status males. • One patrilineage guarantees paternity certainty to another patrilineage. • Female claustration is maintained by both men and the husband’s female kin. Purdah How is paternity certainty guaranteed? • Seclusion Purdah How is paternity certainty guaranteed? • Seclusion • Special architecture for women • Special transportation for women • Special architecture for women • Special transportation for women • Veiling in public Purdah How is paternity certainty guaranteed? • Seclusion • Special architecture for women • Special transportation for women • Veiling in public • Child betrothal Purdah How is paternity certainty guaranteed? • Seclusion • Special architecture for women • Special transportation for women • Veiling in public • Child betrothal • Virginity tests 9 Purdah How is paternity certainty guaranteed? • Seclusion Control of Females/Female Sexuality • Two standards of sexual behavior for men and women • Special architecture for women • Special transportation for women • Veiling in public • Child betrothal • Virginity tests • Genital excision Control of Females/Female Sexuality • Two • standards of sexual behavior for men and women Divorce difficult for women Control of Females/Female Sexuality • Two standards of sexual • • Control of Females/Female Sexuality behavior for men and women Divorce difficult for women Parental choice of marriage partners Control of Females/Female Sexuality • Two standards of sexual • Two standards of sexual • • • • behavior for men and women Divorce difficult for women Parental choice of marriage partners Early marriage for girls • • • behavior for men and women Divorce difficult for women Parental choice of marriage partners Early marriage for girls Live with groom’s family (patrilineal) 10 Control of Females/Female Sexuality • Two standards of sexual • • • • • Control of Females/Female Sexuality • Claustration/ Seclusion behavior for men and women Divorce difficult for women Parental choice of marriage partners Early marriage for girls Live with groom’s family (patrilineal) Ownership of women Control of Females/Female Sexuality • Veiling Control of Females/Female Sexuality • Restricted access to males Control of Females/Female Sexuality • Violence and threat of violence Control of Females/Female Sexuality • Females and their families compete for access to high status males 11 Control of Females/Female Sexuality • Extreme forms with high social status Why is control of female sexuality greater in some societies than others? • Religion • Codifies restrictions and controls on women • Increase in female freedom with more secularization of society Steve McCurry Control of Females/Female Sexuality • Often associated with polygyny • Increased competition between males for mates • Large number of men without mates = more need to sequester women Clitoridectomy/Infibulation • Clitoridectomy: Removal of the clitoris • Infibulation: Removal of the clitoris and part or all of the labia majora, the mons veneris and the labia minora. Surgical closure of the vaginal opening. • More wives = harder to monitor Clitoridectomy/Infibulation • Type I: Clitoridectomy, clitoris excised Clitoridectomy/Infibulation • Type I: Clitoridectomy, clitoris excised • Type II: Clitoridectomy with partial or total excision of the labia minora 12 Clitoridectomy/Infibulation • • • Type I: Clitoridectomy, clitoris excised Type II: Clitoridectomy with partial or total excision of the labia minora Type III: Infibulation, clitoris excised, labia minora excised, labia major fused Clitoridectomy/Infibulation • Deinfibulation: Cutting open scar tissue caused by infibulation to allow for intercourse Clitoridectomy/Infibulation Clitoridectomy/Infibulation • Reinfibulation: Fusing the labia majora shut • Type I: Clitoridectomy, clitoris excised • Type II: Clitoridectomy with partial or total after childbirth. • • • excision of the labia minora Type III: Infibulation, clitoris excised, labia minora excised, labia major fused Deinfibulation: Cutting open scar tissue caused by infibulation to allow for intercourse Reinfibulation: Fusing the labia majora shut after childbirth. Female Genital Excision • 137 million women (as of 1998) • 2 million girls per year • Increased HIV risk 13 Infibulation in Northern Sudan Infibulation in Northern Sudan • Regulating female sexuality in order to safeguard virginity, thus protecting the honor of the woman’s and her husband’s patrilineage. > Guarantees paternity certainty to the husband’s family Infibulation in Northern Sudan • Regulating female sexuality in order to safeguard virginity, thus protecting the honor of the woman’s and her husband’s patrilineage. Infibulation in Northern Sudan • Performed and maintained particularly by older women > Guarantees paternity certainty to the husband’s family > Particularly important in patrilineal, patrilocal and patriarchial societies. Infibulation in Northern Sudan Infibulation in Northern Sudan • Performed and maintained • Performed and maintained • • Threat of female sexuality • Reliance on the patrilineage particularly by older women Threat of female sexuality particularly by older women 14 Infibulation in Northern Sudan • 98% of women have it done Infibulation in Northern Sudan • 98% of women • 39% have immediate substantial complications Infibulation in Northern Sudan • 98% of women • 39% have immediate • substantial complications Movement to stop hampered by civil war Health Risks • • • • • • • • • • • • • Hemorrhage Infection Tetanus Septicimia Fistula Urinary and menstrual function impairment Chronic genital pain Cysts Neuromas Ulcers Incontinence Infertility Chidlbirth complications and risk to newborn Next Time... Ethical Issues • Reproductive Strategies • Marriage and Mating Systems • Reproductive Value 15 Reproductive Success is limited by: Reproductive Success is limited by: • Ability to find and retain a mate • Ability to find and retain a mate • Energetic constraints on reproduction • Energetic constraints on reproduction • Offspring survival • Offspring survival Triver’s Parental Investment Hypothesis • Whichever sex invests more effort and more resources in offspring is, in effect, the limiting resource for the reproduction of the less investing sex and thus the object of competition. Reproductive Success is limited by: • Ability to find and retain a mate • Energetic constraints on reproduction • Offspring survival Trivers, 1972 Male Reproductive Success is limited by: • Ability to find and retain a mate > Human males can exert much more control over females and female sexuality than is seen in most other mammals. Reproductive Success is limited by: • Ability to find and retain a mate > Human males can exert much more control over females and female sexuality than is seen in most other mammals. • Offspring survival > Human males can invest much more in offspring survival (direct care and resources) than in most other mammals. 16 Reproductive Strategies Reproductive Strategies Males and females have different reproductive interests and constraints (even in a couple) What are male reproductive strategies and how do females respond to them? Male Reproductive Strategies Male Reproductive Strategies Control of Females/Female Sexuality Investment in Offspring / Mate Necessary for offspring survival Investment in Mating Effort Investment in Offspring / Mate When male investment won’t increase offspring survival Necessary for offspring survival Paternity certainty is high Access to mates is socially limited Paternity certainty is low Access to mates is socially limited Resources can be passed on Low cost to mating effort Male Reproductive Strategies Control of Females/Female Sexuality Investment in Offspring / Mate More male investment, especially in wealth and resources, leads to increased concern about paternity certainty and thus increased control of female sexuality (by men and female family members) Paternity certainty is high Resources can be passed on Male Reproductive Strategies Control of Females/Female Sexuality Investment in Mating Effort Monopolize females by controlling sexual access to them on a short term basis Investment in Mating Effort Investment in Offspring / Mate Acquire more resources for spouse and children Male-Male Competition Investment in Mating Effort Investment in mating through competition for mates 17 Male Reproductive Strategies Control of Females/Female Sexuality Male-Male Competition Male-Male Competition • Mating Competition • Direct Competition Investment in Offspring / Mate Investment in Mating Effort > > Physical Non physical • Indirect Competition • Resource Competition Direct Competition Sexual Dimorphism Male and Female Homicide Rates How do humans compare? Gorillas Australopithecus (Daly & Wilson, 1988) Male-Male Competition Male-Male Competition • Mating Competition • Mating Competition • Direct Competition • Direct Competition > > Physical Non physical • Indirect Competition • Indirect Competition > • Resource Competition Sperm competition • Resource Competition 18 Sperm Competition Testes & Body Weight • Frequency of multiple-mating • Duration of overlap in multiple-mating Male-Male Competition • Mating Competition • Extreme in humans compared to other primates • Direct Competition > > Resource Competition > Particularly in Stratified societies where the means of production can be controlled Physical Non physical • Indirect Competition > Sperm competition • Resource Competition Male Reproductive Strategies Control of Females/Female Sexuality Investment in Offspring / Mate Male-Male Competition Male Investment • When should males invest in their Investment in Mating Effort spouse and/or children instead of seeking other mating opportunities? 19 Male Reproductive Strategies Male Investment Necessary for offspring survival Paternity certainty is high Aka Hadza Access to mates is socially limited The Ache Resources can be passed on Aka Pygmies Aka Paternal Care • • • Fathers second most active care-givers behind mothers Provided most of care-giving in camp Style of care-giving intimate and affectionate (Hewlett) Aka Paternal Care • Conclusions • Where resources essential to More common if father: • • • • • • No brothers Wife from distant clan Married late Monogamous Small hunting net, more Not high status reliance on traps • Paternal care more common than in other foragers because of type of hunting practiced (net hunting) • Men with fewer resources spend more time in direct child care • survival can be accumulated or where males are the primary contributors to subsistence, fathers invest more time in competing for these resources and thus spend less time in direct child care Where resources are not accumulable men spend more time in direct care of children (Hewlett) 20 Ache of Paraguay Ache of Paraguay Does male investment help offspring survival? (Hill) Hadza of Tanzania Male care of Stepchildren and Biological Children Does paternity effect male investment? (Marlowe, 1999) Male Care and “Fertile” Women in Camp Switch to mating effort with more women in camp Hadza Men • Biological offspring received more care than stepchildren > Male care was not mating effort but paternal investment • Men provide less care to their biological children as their mating opportunities increase (Marlowe, 1999) > Males were investing less in parenting effort than in mating effort when mating opportunities increased. 21 Men’s Reproductive Investment Decisions: Paternity Confidence Men’s Reproductive Investment Decisions: Mate Value • Self-perceived mate value was positively related to mating effort and negatively related to reported paternal investment. Two possible proxies of paternity: 1. Phenotypic Resemblance 2. Perception of mate’s fidelity Men’s perception of their mate’s fidelity and their perceived resemblance to their offspring predicted men’s reported investment in their children. • Men with a high mate value were more likely to reduce their parental investment in relation to reduced mate fidelity as compared to men with a low mate value. But both high and low mate value men react in similar ways to reduced resemblance. • Are low mate value men more likely to tolerate unfaithful mates and lowered paternity? Apicella & Marlowe 2004 Male Reproductive Strategies Control of Females/Female Sexuality Investment in Offspring / Mate Apicella & Marlowe 2007 Male Reproductive Strategies Control of Females/Female Sexuality Male-Male Competition Investment in Mating Effort Investment in Offspring / Mate Male-Male Competition Investment in Mating Effort 22
