Paper Human Sexuality
Discuss childbirth in America, particularly with regards to common medical interventions employed in the labor and delivery process. Please express your opinions on what we, as a society, are getting right (if anything) and on what ought to be changed (if anything). Support your arguments with data from peer-reviewed scientific journal articles. Feel free to discuss prenatal or neonatal care if you wish, but be sure to cover labor and delivery. find , chapter 8 and 9
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Discovering Human Sexuality THIRD EDITION
Available free of charge, this online companion to the textbook provides a thorough set of study tools that includes questions, activities, flashcards, and other
resources to help you learn the material quickly and effectively.
Animations (included in the Activities) clearly explain important concepts and processes in easy-to-follow narratives.
A comprehensive set of Study Questions covers the full range of content in every chapter. Each
question is referenced to a textbook section, for review.
Labeling Activities and dynamic step-by-step illustrations simplify complex concepts and reinforce
important anatomy and terminology.
Companion Website
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WEB ACTIVITIES The following activities are available on the site.
Page numbers indicate where in the textbook each is referenced.
ADDITIonAL fEATurES Chapter outlines & Summaries provide a thorough review of each chapter.
Learning objectives in the form of short-answer questions help you focus on the important topics in each chapter.
Quizzes with multiple choice and essay questions allow you to test your comprehension of each chapter and synthesize and apply the concepts you have learned. (Instructors must register in order for their students to be able to take the quizzes.)
flashcards help you quickly learn and review all the important terminology introduced in each chapter.
In addition, the website includes a set of Web Links for each chapter, as well as a complete Glossary.
2.1 The Vulva . . . . . . . . . . . . . . . . . . 22
2.2 Internal Anatomy of the Vulva. . . . . . . . . . . . . . . . . . . . . . . . 29
2.3 The Female Reproductive Tract, Part 1. . . . . . . . . . . . . . . 30
2.4 The Female Reproductive Tract, Part 2. . . . . . . . . . . . . . . 30
2.5 The Pap Test. . . . . . . . . . . . . . 34
2.6 Ovarian and Uterine Cycles . . . . . . . . . . . . 38, 42, 43
2.7 Main Processes of the Menstrual Cycle . . . . . . . . . . 43
2.8 The Reproductive Years . . . . . . . . . . . . . . . . . . . . . . . 44
2.9 Internal Structure of the Lactating Breast. . . . . . . . . . 51
_____________________________________
3.1 The Male External Genitalia . . . . . . . . . . . . . . . . . . . 62
3.2 Internal Structure of the Erect Penis and the Urethra . . . . . . . . . . . . . . . . . . . . . 65
3.3 The Mechanism of Erection . . . . . . . . . . . . . . . . . . . . 69
3.4 The Scrotum and Its Contents. . . . . . . . . . . . . . . . . . . 71
3.5 Internal Structure of the Testicle and Epididymis. . . . . . . . . . . . . . . . . 73
3.6 The Male Reproductive Tract . . . . . . . . . . . . . . . . . . . . . . . . 74
3.7 Anatomy of the Prostate. . . . . . . . . . . . . . . . . . . . 76
_____________________________________
4.1 Development of the Male and Female Reproductive Tracts. . . . . . . . . . . . . . . . . . . . . . . 89
_____________________________________
7.1 Definitions of Sexual Relationships . . . . . . . . . . . 192
7.2 Sternberg’s Seven Types of Love . . . . . . . . . . . . . . . . . . . 209
_____________________________________
8.1 How a Home Pregnancy Test Works . . . . . . . . . . . . . . 229
8.2 In Vitro Fertilization. . . . . 232 _____________________________________
9.1 Vasectomy . . . . . . . . . . . . . . 291
9.2 Tubal Sterilization . . . . . . 292 _____________________________________
15.1 Milestones in the Global HIV/AIDS Pandemic . . . 480
_____________________________________
a.1 Mitosis . . . . . . . . . . . . . . . . . . . 552
a.2 Mitosis Time-Lapse Video . . . . . . . . . . . . . . . . . . . . . 552
a.3 Meiosis. . . . . . . . . . . . . . . . . . . 552
a.4 Differences and Similarities between Meiosis and Mitosis . . . . . . . . . . . . . . . . . . . 552
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Discovering Human Sexuality
third edition
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Sinauer Associates, Inc. Publishers Sunderland, Massachusetts U.S.A.
Discovering Human Sexuality
third edition
Simon LeVay west hollywood, california
Janice Baldwin university of california
santa barbara
John Baldwin university of california
santa barbara
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Discovering Human Sexuality, Third Edition Copyright © 2015 by Sinauer Associates, Inc. All rights reserved. This book may not be reproduced in whole or in part without permission from the publisher.
For information or to order, address: Sinauer Associates P.O. Box 407 Sunderland, MA 01375 USA Fax: 413-549-1118 E-mail: publish@sinauer.com Internet: www.sinauer.com
Library of Congress Cataloging-in-Publication Data
LeVay, Simon. Discovering human sexuality / Simon LeVay, West Hollywood, CA, Janice Baldwin, University of California, Santa Barbara, John Baldwin, University of California, Santa Barbara. — Third edition. pages cm ISBN 978-1-60535-275-6 (alk. paper) 1. Sex (Psychology) 2. Sex (Biology) 3. Sex–Social aspects. I. Baldwin, Janice I. II. Baldwin, John D., 1941- III. Title. BF692.L47 2015 306.7–dc23 2014044757
Printed in the USA 5 4 3 2 1
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Simon LeVay, PhD is a British-born neuroscientist turned writer and teacher. He has served on the faculties of Harvard Medical School and the Salk Institute for Biologi- cal Studies and has taught at Harvard; the University of California, San Diego; and Stanford University. He is best known for a 1991 study that described a difference in brain structure between heterosexual and homosexual men; this study helped spark a wealth of new research on the biology of sexual orientation. LeVay is the author or coauthor of 11 books, the most recent of which is a historical novel, The Donation of Constantine (Lambourn, 2013).
Janice Baldwin, PhD and John Baldwin, PhD are sociologists at the University of California, Santa Barbara. They have been collaborators in numerous studies and coauthored many articles in the areas of play, creativity, sexuality, and sex educa- tion, as well as the textbook Behavior Principles in Everyday Life (Prentice Hall). John Baldwin’s latest book is Ending the Science Wars (Paradigm, 2008). The Baldwins co- teach an undergraduate human sexuality course that is regularly voted best course at UCSB. They also teach an advanced seminar course on the same topic. Their students run a sex-ed website, SexInfoOnline (www.SexInfoOnline.com).
About the Authors
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chapter 1 Sexuality: Pathways to Understanding 3
chapter 2 Women’s Bodies 21
chapter 3 Men’s Bodies 61
chapter 4 Sex, Gender, and Transgender 87
chapter 5 Attraction, Arousal, and Response 123
chapter 6 Sexual Behavior 155
chapter 7 Sexual Relationships 191
chapter 8 Fertility, Pregnancy, and Childbirth 227
chapter 9 Contraception and Abortion 265
chapter 10 Sexuality across the Life Span: From Birth to Adolescence 305
chapter 11 Sexuality across the Life Span: Adulthood 335
chapter 12 Sexual Orientation 365
chapter 13 Atypical Sexuality 401
chapter 14 Sexual Disorders 431
chapter 15 Sexually Transmitted Infections 461
chapter 16 Sexual Assault, Harassment, and Partner Violence 493
chapter 17 Sex as a Commodity 523
appendix a Sex and Evolution 551
appendix b Sex and the Nervous System 573
Brief Contents
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Contents
Sexuality Is a Broader Concept than Sex 4
Studying Sexuality Has Practical Benefits 4
Sexuality Has Changed over Time 4 Sexuality has been influenced by evolution 5
Society has changed sexuality 5
Box 1.1 Meet My Dads 6
Marriage has been transformed 8
Sex has become a topic of social discourse 9
Social movements have affected sexuality 10
Box 1.2 Freud and Hirschfeld: Contrasting Theories on Sexual Orientation 11
Sexuality Can Be Studied with a Wide Variety of Methods 12
Biomedical research focuses on the underlying mechanisms of sex 12
Psychology includes diverse approaches to sexuality 13
Sociologists focus on the connection between sex and society 15
The economic approach weighs costs and benefits 16
Chapter 1 Sexuality: Pathways to Understanding 3
A Woman’s Vulva Includes Her Mons, Labia, Vaginal Opening, and Clitoris 22
There is more to the clitoris than meets the eye 24
Box 2.1 Female Genital Cutting 26
The appearance of the vaginal opening is variable 27
The Vagina Is the Outermost Portion of the Female Reproductive Tract 29
The vagina undergoes changes during arousal 31
The G-spot is a controversial erogenous zone 31
The Anus Can Also Be a Sex Organ 32
The Uterus Serves a Double Duty 32 Box 2.2 Genital Self-Examination 33
Cancer can affect the cervix or the endometrium 34
Other uterine conditions include fibroids, endometriosis, abnormal bleeding, and prolapse 35
Should hysterectomy be so common? 36
The Oviducts Are the Site of Fertilization 36
The Ovaries Produce Ova and Sex Hormones 37
Box 2.3 The Feedback Loop that Controls Female Hormone Production 38
Menstruation Is a Biological Process with Cultural and Practical Aspects 40
Box 2.4 Menstrual Synchrony: Reality or Myth? 41
The menstrual cycle has three phases 42
The cycle is driven by hormonal changes 43
Does the menstrual cycle influence sexuality? 44
Attitudes toward menstruation vary 44
Box 2.5 Attitudes toward Menstruation 45
Women use pads, tampons, or cups during menstruation 46
Menstrual Problems Are Common but Treatable 48
Menstrual pain may or may not reflect underlying pelvic disease 48
The premenstrual syndrome has physical and psychological aspects 48
Menstruation stops during pregnancy—and for many other reasons 49
Sex steroids affect systems in women besides the reproductive tract 50
The Breasts Have Both Erotic and Reproductive Significance 50
Chapter 2 Women’s Bodies 21
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x CONTENTS
Breast cancer mortality can be reduced 51
Many factors affect the risk of breast cancer 52
Early detection is important 54
Box 2.6 Breast Self-Examination 55
Treatment depends on the diagnostic findings and the woman’s choice 56
Most women with breast cancer return to an active sex life 56
The Male External Genitalia Are the Penis and Scrotum 62
The penis combines erotic, reproductive, and urinary functions 63
Box 3.1 Male Circumcision 64
Box 3.2 How Big Should a Penis Be? 67
Box 3.3 Diphallia 68
Penile Erection Involves Nerves, Blood, and Chemistry 68
Erection is filling of the penis with blood 69
Muscles are also involved in erection 70
Erections occur during sleep 70
The scrotum regulates the temperature of the testicles 70
The Testicles Produce Sperm and Sex Hormones 71
Other glands contribute secretions to the semen 73
What is semen? 74
Box 3.4 Disorders of the Testicles 75
Box 3.5 Disorders of the Prostate Gland 76
Ejaculation Requires Coordination of Muscles and Glands 77
The testicles secrete sex hormones 78
Box 3.6 Designer Steroids 80
The brain and pituitary gland regulate hormone levels 80
Nudity Is Culturally Regulated 81
Chapter 3 Men’s Bodies 61
Genes and Hormones Guide Sex Development 88
Female and male reproductive tracts develop from different precursors 88
Female and male external genitalia develop from the same precursors 89
The gonads descend during development 91
Puberty is sexual maturation 92
The brain also differentiates sexually 92
Sex Development May Go Awry 93 Chromosomal anomalies affect growth and fertility 93
The gonads or genitals may be sexually ambiguous 95
Box 4.1 My Life with Androgen Insensitivity Syndrome 96
Gender Is a Central Aspect of Personhood 97 Gender identity might not match anatomical sex 97
Women and men differ in a variety of cognitive and personality traits 98
There are Many Sex Differences in Sexuality 99
Many gender differences arise early in life 101
Biological Factors Influence Gender 102
Evolutionary forces act differently on females and males 102
Box 4.2 Gendered Play in Primates 103
Experiments demonstrate a role for sex hormones 103
Life Experiences Influence Gender 105 Gender is molded by socialization 105
Cognitive developmental models emphasize thought processes 108
Gender Development Is Interactive 108 Box 4.3 The Boy Who Was Raised as a Girl 109
Transgender People Cross Society’s Deepest Divide 110
Box 4.4 Trans Men and Women in Cross- Cultural Perspective 111
Transexual individuals are of more than one kind 112
Changing sex is a multistage process 113
Some transgender people do not want surgery 115
Box 4.5 How Should We Treat Gender- Dysphoric Children? 116
Trans people struggle for awareness and acceptance 118
Chapter 4 Sex, Gender, and Transgender 87
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CONTENTS xI
Sexual Attraction: It Takes Two 124 Beauty is not entirely in the eye of the beholder 124
Culture influences the attractiveness of bodies 126
Attractiveness involves senses besides vision 129
Behavior and personality influence sexual attractiveness 130
Box 5.1 Sex Pheromones 131
Familiarity may increase or decrease attraction 133
Perceived attractiveness varies around the menstrual cycle 135
Judgments of attractiveness change as people get to know each other 136
Asexual women and men do not experience sexual attraction 136
Sexual Arousal Has Multiple Roots 137 Fantasy is a common mode of sexual arousal 138
Arousal occurs in response to a partner 139
Hormones influence sexual arousability 140
Conditioning may influence arousal 141
Box 5.2 Aphrodisiacs and Drugs 142
Sexual Arousal Follows a Response Cycle 143
In the excitement phase, genital responses begin 143
In the plateau phase, arousal is maintained 144
Orgasm is the climax of sexual arousal 145
Box 5.3 Female Ejaculation 146
Brain imaging suggests where orgasm may be experienced 147
Box 5.4 Foot Orgasms 148
In the resolution phase, arousal subsides 149
The phases may be linked in different ways 149
Some people experience multiple orgasms 150
Men experience a refractory period 151
The Masters and Johnson cycle may be incomplete 151
Chapter 5 Attraction, Arousal, and Response 123
People Derive Pleasure from Diverse Sexual Behaviors 156
Masturbation Is a Very Common Form of Sexual Expression 156
Box 6.1 Sex and Happiness 157
Negative attitudes toward masturbation are still prevalent 158
Several demographic factors influence masturbation 158
Women use more diverse techniques of masturbation than men 160
Gay people masturbate more than heterosexuals 161
Different cultures have different attitudes toward masturbation 161
The Kiss Represents True Love— Sometimes 162
Sexual Touching Takes Many Forms 163
Oral Sex Is Increasingly Popular 164 Fellatio is oral stimulation of the penis 164
Cunnilingus is oral stimulation of the vulva 165
Most Heterosexual Sex Includes Coitus 166 Coitus can be performed in many different
positions 166
The man-above position is a traditional favorite 167
The women’s movement encouraged alternative positions 168
Box 6.2 Progress in Coitus Research 169
Box 6.3 Sex and the Seasons 171
Anal Sex May Be a Part of Either Heterosexual or Male Homosexual Behavior 172
Men and Women May Have Different Preferences for Sexual Encounters 173
Sex Toys Are Used to Enhance Sexual Pleasure 174
Sex May Be in Groups 177 Box 6.4 What Is “Great Sex”? 178
Sexual Behavior and Attitudes Vary among Cultures 179
The Kama Sutra is the classic work on how to make love 179
The Aka emphasize the importance of frequent sex 181
Many Disabled People Have Active Sex Lives 181
Box 6.5 On Seeing a Sex Surrogate 182
Many intellectually disabled people are competent to make sexual choices 183
Spinal cord injuries present a major challenge to sexual expression 184
Arthritis is the number one disability affecting sex 186
Chapter 6 Sexual Behavior 155
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xII CONTENTS
Sexual Relationships Are Motivated by Many Factors 192
Moral Judgments about Sex Depend on Its Context 192
Demographic factors affect sexual attitudes 192
Box 7.1 Who May Marry? 194
Americans’ Attitudes Have Changed over Time 195
Casual Sex Has More Appeal to Men than to Women 196
Hooking up—the new norm? 196
Box 7.2 Straight Women, Gay Sex 197
Hookups can be pleasurable or abusive 198
Hookups can have positive or negative consequences 200
Casual sex is more accepted in the gay male community 200
Negotiating sex involves flirting 201
Box 7.3 Flirting Styles 202
Non-Cohabiting Relationships Are Often Short-Lived 203
Same-sex relationships have their own scripts 205
Non-cohabiting relationships may evolve rapidly 205
Love Cements Many Sexual Relationships 206
There are different kinds of love 206
Being in love may be the justification for marriage or sex 206
Liking and reciprocal attraction precede falling in love 206
Researchers are probing the biological basis of love 207
One theory proposes that love has three components 208
Unrequited Love Is Painful for Both Parties 210
Box 7.4 Love Stories 211
The rejector may experience guilt 212
Life Experiences Mold Our Sexual Relationships 213
Relationship styles are influenced by childhood attachments 213
Couples in relationships resemble each other 213
Communication Is a Key Factor in the Success of Relationships 214
Communication may be inhibited by upbringing or by the gender barrier 214
Relationship and marriage education teaches communication skills 215
How couples deal with conflict affects the stability of their relationship 216
Love, Jealousy, and Infidelity Are Intertwined 218
Jealousy can have a positive function 218
Extra-Pair Relationships Have Many Styles and Motivations 219
Personal and evolutionary factors influence infidelity 220
Box 7.5 We Just Clicked 221
Extra-pair relationships are uncommon 222
Chapter 7 Sexual Relationships 191
Pregnancy and Childbirth Raise Major Health Concerns 228
Pregnancy Is Confirmed by Hormonal Tests 228
Box 8.1 Birth Facts 229
Infertility Can Result from a Problem in the Woman or in the Man 230
A variety of factors can reduce sperm counts 230
Box 8.2 Declining Sperm Counts? 231
In vitro fertilization can circumvent many sperm problems 232
Box 8.3 Choosing Children’s Sex 234
Sperm can be donated 235
Abnormalities of the female reproductive tract may reduce fertility 236
Failure to ovulate can be dealt with by drugs or by egg donation 236
Surrogate mothers bear children for others 236
Adoption is limited by the supply of healthy infants 237
Fertility declines with age 237
Many Embryos Do Not Survive 239 Rh factor incompatibility can threaten second
pregnancies 239
Ectopic pregnancy can endanger the mother’s life 239
Chapter 8 Fertility, Pregnancy, and Childbirth 227
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CONTENTS xIII
Pregnancy Is Conventionally Divided into Three Trimesters 240
The First Trimester Is a Period of Major Changes 240
Prenatal care provides health screening, education, and support 242
Adequate nutrition is vital to a successful pregnancy 242
Tobacco, alcohol, drugs, and radiation can harm the fetus 243
The Second Trimester Is the Easiest 245 Tests can detect fetal abnormalities 245
Sex during pregnancy is healthy 247
Moderate exercise during pregnancy is beneficial 248
The Third Trimester Is a Time of Preparation 248
A hospital is the best location for childbirth if complications are foreseen 249
Childbirth classes prepare parents for birth 249
The fetus also makes preparations for birth 250
Labor Has Three Stages 251
The first stage of labor is marked by uterine contractions and cervical dilation 251
Box 8.4 Pain-free Childbirth 253
The second stage is the delivery of the baby 254
The newborn child adapts quickly 255
The third stage is the expulsion of the placenta 255
Box 8.5 Cesarean Section 256
Premature or delayed birth is hazardous 256
The Period after Birth Places Many Demands on Parents 257
Postpartum depression may be accompanied by disordered thinking 258
Childbirth and parenthood affect sexuality 258
Breast-Feeding Is the Preferred Method of Nourishing the Infant 259
Lactation is orchestrated by hormones 259
The content of breast milk changes over time 259
Infant formula is an alternative to breast milk 260
Breast-feeding has many advantages and some drawbacks 260
Birth Control Has a Long History 266 Feminists led the campaign to legalize
contraception 266
Box 9.1 Margaret Sanger and the Birth Control Movement 267
Contraception has not yet solved the problem of unintended pregnancy 268
Different users have different contraceptive needs 268
Physical Methods Block Sperm Transport 270
Male condoms are reliable when properly used 270
Female condoms are relatively intrusive 272
Box 9.2 Male Contraceptives of the Future? 273
Diaphragms and cervical caps are inconvenient but have few side effects 274
Spermicides are not very reliable when used alone 275
Intrauterine devices require little attention 276
Hormone-Based Methods Are Easy to Use 277
Combination pills offer health benefits 278
Continuous use of combination pills eliminates menstrual periods 280
Progestin-only pills have fewer side effects 281
Hormones Can Be Administered by Non-Oral Routes 282
Depo-Provera lasts three months 282
Transdermal patches last a week 283
Vaginal rings last three weeks 284
Implants are extremely reliable 285
Behavioral Methods Can Be Demanding 285 In fertility awareness methods, couples avoid coitus
during the fertile window 285
The withdrawal method is simple but challenging 287
Noncoital sex can be used as a means of avoiding pregnancy 288
There Are Contraceptive Options after Unprotected Coitus 289
Sterilization Is Highly Reliable 290 Vasectomy is a brief outpatient procedure 290
Tubal sterilization is more invasive and expensive 292
Disabled Persons Have Special Contraceptive Needs 293
Several Safe Abortion Procedures Are Available 293
Chapter 9 Contraception and Abortion 265
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xIV CONTENTS
Box 9.3 Abortion in the United States: Key Statistics 294
Vacuum aspiration is the standard first-trimester surgical method 295
Dilation and evacuation is used early in the second trimester 295
Induced labor and hysterotomy are performed late in the second trimester 296
Medical abortions are two-step procedures 296
Abortions do not cause long-lasting ill effects 297
Box 9.4 Does Abortion Traumatize Women? 298
Americans Are Divided on Abortion, but Most Favor Restricted Availability 298
The availability of abortion is decreasing 299
Box 9.5 Feticide 301
Some Forms of Childhood Sexual Expression Are Common 306
Primates display sexual behavior early in life 306
In contemporary Western culture, children are insulated from sex 306
Some children engage in solitary sexual activity 307
Box 10.1 Talking with Children about Sex 308
Sex with others can occur during childhood 309
Cultures vary in their attitudes toward childhood sexuality 310
Some Children Have Sexual Contacts with Adults 311
Most adult-child contacts involve older children and are single encounters 311
Some kinds of adult-child sex are more harmful than others 311
Strategies to prevent adult-child sex are quite effective 312
Box 10.2 Sex and Suggestibility 313
Preadolescence May Be Marked by an Increase in Sexual Interest 314
Preadolescent children segregate by sex 314
Strict gender norms may traumatize children who become gay adults 314
Puberty Is a Period of Rapid Maturation 315 Puberty is marked by visible and invisible changes 315
Box 10.3 My First Period 317
Puberty occurs earlier in girls than boys 318
What drives puberty? 319
The body signals its readiness for puberty to the brain 320
Puberty may come too early or too late 321
Adolescence Is a Time of Sexual Exploration 322
Many cultures have puberty rites 322
There are social influences on teen sexual behavior 323
Social media have risks and benefits 324
Males masturbate more than females 325
The sexual behavior of American teens has increased and diversified 326
Box 10.4 Losing It 327
Noncoital sex is popular among teens 328
Teen Sexuality Is Central to Identity Development 329
Teen relationships are often short-lived 330
Teen pregnancy is declining but is still too common 330
Chapter 10 Sexuality across the Life Span: From Birth to Adolescence 305
In Young Adulthood, Conflicting Demands Influence Sexual Expression 336
Most young men and women have only a few sex partners 336
Cohabitation Is an Increasingly Prevalent Lifestyle 337
Box 11.1 Cohabitation: Laws in Conflict 337
Cohabitation has diverse meanings 338
Cohabitation does not harm a subsequent marriage 339
Chapter 11 Sexuality across the Life Span: Adulthood 335
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CONTENTS xV
Marriage Takes Diverse Forms 339 The formalization of sexual unions has social
and personal functions 340
Many societies have permitted polygamy 340
Box 11.2 Mormon Polygamy 341
Polyamory includes a variety of nonmonogamous relationships 342
The Institution of Marriage Is Evolving 343 Box 11.3 Extreme Marriages 344
Companionate marriage makes the availability of divorce a necessity 344
Marriage is becoming a minority status 345
Relationship options have diversified 345
Most Long-Term Couples Are Satisfied with Their Sex Lives 346
The frequency of sex declines in the course of long-term relationships 347
Marital satisfaction declines during middle age 348
Many Factors Bring Relationships to an End 348
Box 11.4 You Know the Future of Your Marriage 349
Dissimilarity between husbands and wives shortens marriages 350
Marital Disruption Can Have Negative and Positive Consequences 351
Divorced men and women can suffer psychological, physical, and economic damage 351
Divorce may be the start of a new life 351
Many divorced people remarry 352
Does marriage have a future? 352
Menopause Marks Women’s Transition to Infertility 353
Menopause may be caused by depletion of ova 354
Women may experience a decline in sexual desire at menopause 354
Decreased hormone levels affect a woman’s physiology 355
Hormone therapy can reduce menopausal symptoms 355
Ethnicity influences the experience of menopause 356
Men’s Fertility Declines Gradually with Age 357
The Sex Lives of Old People Have Traditionally Been Ignored 357
Aging is accompanied by physiological changes in the sexual response 359
Medical conditions, drugs, and social factors can impair the sexuality of older people 359
Box 11.5 Seniors on Sex 360
The experience of aging affects people in diverse ways 360
There Is a Spectrum of Sexual Orientations 366
Sexual Orientation Is Not an Isolated Trait 367
Diverse Theories Attempt to Explain Sexual Orientation 368
Box 12.1 Boys Will Be Girls 369
Freud proposed psychodynamic models 370
Sexual orientation has been attributed to socialization 370
Biological theories focus on prenatal hormones and genes 371
Box 12.2 Why Gay Genes? 374
The Gay Community Has Struggled for Equal Rights 375
The gay rights movement began in Germany 375
Box 12.3 Gay Martyrs 376
Gay rights are a global issue 377
Growing Up Gay Presents Challenges 379 Box 12.4 Global Perspectives on Sexual Orientation 380
Box 12.5 Gay and Homeless 381
Coming out is a lifelong process 382
Lesbians and gay men are well represented in certain occupations 383
Gay People Who Belong to Minorities Have Special Concerns 384
Gay Sex Has Its Own Style 385 There is diversity within the gay community 386
Some gay people are parents 387
Changing One’s Sexual Orientation Is Difficult or Impossible 388
Homophobia Has Multiple Roots 389
Chapter 12 Sexual Orientation 365
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xVI CONTENTS
Cultural indoctrination transmits homophobia across generations 390
Gays are seen as rule breakers 391
Overcoming homophobia is a grassroots enterprise 392
Bisexual People Are Caught between Two Worlds 393
The prevalence of bisexuality depends on definitions 393
Bisexual people face prejudice 395
Lesbian, gay, straight, bi, other—more alike than different 396
Sexual Variety Is the Spice of Life 402 Most fetishes are related to the body 402
Box 13.1 Rubber Fetishism and the Internet 405
People cross-dress for a variety of reasons 406
Some men are aroused by trans women 407
Sadomasochism involves the infliction or receipt of pain or degradation 407
Box 13.2 In the Dungeon 409
Adult babies reenact infancy 410
Paraphilic Disorders Cause Distress or Harm Others 410
Exhibitionists expose themselves to nonconsenting persons 412
Obscene telephone calling is related to exhibitionism 413
Voyeurs are aroused by watching others 413
Frotteurism involves surreptitious physical contact 414
Some Adults Are Sexually Attracted to Children 414
Box 13.3 Frotteurism on Public Transit 415
Pedophilia and child molestation are not synonymous 415
Child molestation is a behavioral and legal term 417
Priests and others may molest children under their care 417
Some organizations support “minor-attracted people” 418
A Variety of Other Paraphilic Disorders Exist 418
Zoophiles are sexually attracted to animals 418
In necrophilia, nonresistance of the partner may be arousing 419
Sexual violence can be paraphilic 420
Box 13.4 Autoerotic Asphyxia 421
Sex Offenders Do Not Necessarily Repeat Their Offenses 422
There Are Numerous Theories of Paraphilic Disorders 422
Theories of Causation Have Suggested a Variety of Treatments 424
Conditioning is intended to change sexual desires 425
Cognitive therapy is aimed at preventing repeat offenses 425
The efficacy of psychological treatments is doubtful 426
Drug treatments interact with neurotransmitters or hormones 426
Castration is a treatment of last resort 427
Few “Kinks” Are Disorders 428
Chapter 13 Atypical Sexuality 401
Sexual Disorders Are Common 432 Men’s and women’s sexual problems differ 432
A multidisciplinary approach to treatment is preferred 432
Premature Ejaculation Is Men’s Number One Sex Problem 433
Box 14.1 Sensate Focus 434
There are different kinds of premature ejaculation 435
Sex therapy may help men to regulate excitation 436
Drug treatment may be effective 437
There Are Multiple Causes for Delayed Ejaculation 437
Erectile Disorder Has Many Causes and Treatments 438
Erectile disorder can have physical or psychological causes 438
Simple measures may alleviate the problem 439
Psychological treatments may be useful 439
Chapter 14 Sexual Disorders 431
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CONTENTS xVII
Viagra and similar drugs have become the leading treatments 440
Erectile disorder can be treated with devices and implants 441
Men May Have Little Interest in Sex 442
Sexual Pain Is Uncommon in Men 443
Female Sexual Arousal Disorder Involves Insufficient Genital Response 443
There Are Many Reasons for Sexual Pain in Women 444
Vaginismus may make intercourse impossible 445
Box 14.2 Dyspareunia: A Case History 446
Difficulty in Reaching Orgasm Is Common among Women 447
Psychotherapy and directed masturbation may be helpful 447
Box 14.3 Kegel Exercises 449
Faked orgasms offer a questionable solution 450
Too Much Interest in Sex Can Cause Problems 450
Compulsive sexual behavior can often be treated with SSRIs 451
Lack of Desire for Sex Is Not Necessarily a Problem 452
Estrogen or androgen treatment may improve sexual desire in women 452
Box 14.4 Sexual Minorities and Sexual Disorders 453
Sex therapy may be helpful for low sexual desire in women 454
New views on women’s response cycles may influence treatment options 455
Venereal Diseases Were Seen as Punishment for Sexual License 462
STIs Are Still Major Problems in the United States 462
Lice and Mites Are More of an Annoyance Than a Danger 465
Pubic lice itch, and that’s all they do 465
Scabies may be transmitted sexually or nonsexually 466
Trichomoniasis Is Caused by a Protozoan 467
Bacterial STIs Can Usually Be Treated with Antibiotics 467
Syphilis Is Down but Not Out 467 Untreated syphilis progresses through three stages 468
Syphilis has resisted elimination 469
Gonorrhea Can Lead to Infertility 469 Box 15.1 The Tuskegee Syphilis Study 470
Chlamydia Causes a Common Infection with Serious Complications 471
The Status of Bacterial Vaginosis as an STI Is Uncertain 473
Urethritis Can Be Caused by a Variety of Organisms 473
Viral STIs Can Be Dangerous and Hard to Treat 474
Molluscum Contagiosum Is a Self-Limiting Condition 474
Genital Herpes Is a Lifelong but Not Life- Threatening Infection 474
Recurrent outbreaks are the rule 475
Drug treatment can shorten or prevent outbreaks 476
Human Papillomaviruses Can Cause Genital Warts—and Cancer 477
HPV vaccines are available 478
Hepatitis Viruses Can Be Sexually Transmitted 479
AIDS Is Caused by the Human Immuno- deficiency Virus 479
Sexual transmission is chiefly by coitus and anal sex 481
HIV infection progresses in a characteristic way 482
Antiretroviral drugs suppress but don’t eliminate HIV 482
You Can Reduce Your STI Risks 484 Abstinence prevents STIs 484
Sexually active people can reduce their risk of STIs 485
Some sexual behaviors are riskier than others for STI transmission 485
Box 15.2 STIs and the Law 486
Condoms are the mainstay of STI prevention 487
Not Everything Is an STI 487
Chapter 15 Sexually Transmitted Infections 461
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xVIII CONTENTS
Can Money Buy You Love? 524 Historically, prostitution was viewed as a necessary
evil 524
Prostitution is on the decline 524
Box 17.1 Courtesans 525
There Is a Hierarchy of Prostitution 526 Street prostitution has many risks 526
Box 17.2 The Economics of Prostitution 527
Female, male, and transgender streetwalkers have different experiences 528
Some prostitutes work out of massage parlors and strip clubs 529
Escort services are the main form of prostitution in the United States 530
Only a minority of men use prostitutes 532
Some women use male prostitutes 532
Juvenile prostitution is of special concern 532
Box 17.3 Juvenile Prostitutes in Portland, Oregon 533
Sex trafficking is a global business 534
There Are Conflicting Views on Prostitution 536
There are several options for legal reform 537
There Is More to Sex Work than Prostitution 538
Stripping is going mainstream 538
Phone sex has diversified 539
Pornography Has Always Been Part of Human Culture 539
Pornography has battled censorship 540
New technologies mean new kinds of pornography 540
Box 17.4 What’s It Like to Be a Porn Star? 542
Chapter 17 Sex as a Commodity 523
What Is Rape? 494 Young women are the most frequent victims of rape 494
Most rapes are not reported 495
Most perpetrators are men known to the victims 495
College Rapes Are Becoming Less Common 496
Box 16.1 It Happened to Me 497
The number one “date rape drug” is alcohol 499
Rape Can Have Severe Effects on the Victim 500
Box 16.2 Reducing the Risk of Rape 501
Services are available for rape victims 501
Rape can inflict long-lasting harm 502
Box 16.3 Ten Ways Men Can Prevent Sexual Violence 503
Male victims have special concerns 504
LGBT people are at high risk 505
Rape Laws Have Become More Protective of Victims 506
Reforms began in the 1970s 506
What happens to men who rape? 506
Repeat offending is common 507
Why Do Men Rape? 508 Rape may have evolutionary roots 508
Some characteristics distinguish rapists from nonrapists 508
Social forces influence the likelihood of rape 509
Intervention Programs Are of Uncertain Value 509
Box 16.4 Rape and War 510
Intimate Partner Violence Is a Crime with Many Names 511
Intimate partner violence follows an escalating cycle 513
Breaking up is hard to do 513
Help is available 514
Sexual Harassment Occurs in Many Environments 514
There are two kinds of workplace sexual harassment 515
Sexual harassment often begins early 516
Sexual harassment harms its victims 517
Victims of sexual harassment can take steps to end it 517
There Are Three Kinds of Stalkers 518
Chapter 16 Sexual Assault, Harassment, and Partner Violence 493
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CONTENTS xIx
There is some pornography for women 543
There Are Conflicting Perspectives on the Value or Harm of Pornography 544
Research has not resolved the question of pornography’s effects 545
Sex Is Part of the Mass Media 546 Sex sells, sometimes 546
Rival Theories Offer Explanations for Sexual Reproduction 552
Sexual reproduction may remove harmful mutations 553
Sexual reproduction may generate beneficial gene combinations 554
Future research may solve the puzzle 554
Why Are There Two Sexes? 555 Hermaphrodites combine male and female reproductive
functions 556
Evolution Has Led to Diverse Methods of Sex Determination 556
In mammals, sex is determined by chromosomes 557
Sexual Selection Produces Anatomical and Behavioral Differences between Males and Females 557
Males and females follow different reproductive strategies 557
Females and males are exposed to different reproductive risks 558
Males often compete for access to females 558
Females often choose among males 559
Sometimes males make significant investments in reproduction 562
If males invest, sexual selection may work differently 562
Diverse Relationship Styles Have Evolved 563
Social and sexual arrangements are not necessarily the same 563
Male promiscuity offers obvious evolutionary benefits 564
Why are females promiscuous? 564
Female promiscuity leads to adaptive responses by males 565
Males may copulate with females by force 566
Sometimes, Helping Relatives Reproduce Is a Good Strategy 567
Avoiding Incest Is an Evolved Behavior 568
Sex Has Acquired Other Functions beyond Reproduction 568
Female and male bonobos engage in nonreproductive sex 568
Bonobos use sex for conflict resolution and alliance formation 569
Appendix A Sex and Evolution 551
Box B.1 The Nervous System 574
Erection Can Be Mediated by a Spinal Reflex 576
Sensory innervation of the genitalia 577
The pudendal and pelvic nerves 577
Erectile Tissue Forms a Hydraulic System 578
Muscles Are Also Involved in Erection 579
The Brain Influences Erection and Ejaculation 580
Appendix B Sex and the Nervous System 573
Glossary 583
Photo Credits 595
References 597
Author Index 631
Subject Index 635
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Preface
This past year was tough, making the switch to LeVay et al., but I’m glad I did it. Discovering Human Sexuality is unique in both approach and content. The authors have a point of view, but still provide balanced coverage of contro- versial issues. The boxes are wonderful. One of the things I like about it is the inclusion of historical and cross-cultural detail in the boxes. It’s a very readable and beautiful book. The illustrations and diagrams are excellent—the best of any text I have ever used.
Josephine Caldwell-Ryan Southern Methodist University
Discovering Human Sexuality, Third Edition, is the continuation of a textbook that originated in 2003 with the publication of Human Sexuality by Simon LeVay and Sharon Valente. Since then, the book has gone through several changes of author- ship, format, and title. One consistency, however, has been the identity of the lead author. Another has been the book’s high academic and pedagogical standards, which have earned it a prominent place in the market and broad praise from review- ers and users, including the kind words cited above.
The Second Edition of Human Sexuality appeared in 2006 with the same two authors. For the 2009 edition, however, Janice Baldwin replaced Sharon Valente. Also, we decided to produce two distinct versions of the book. One of them— Human Sexuality, Third Edition—continued the approach pioneered in the earlier editions. The other, which we titled Discovering Human Sexuality, was a somewhat shorter and more accessible version that demanded less prior knowledge on the part of the students, especially in the area of biol- ogy. John Baldwin joined LeVay and Janice Baldwin as third author of this version. In 2012 we continued with the same two versions (Human Sexuality, Fourth Edition, and Discover- ing Human Sexuality, Second Edition).
For the current edition we have decided to merge the two versions into one, which we have titled Discovering Human Sexuality, Third Edition. It was a difficult decision to make because both versions had been successful in the market- place and each served a somewhat different need. However, the workload involved in producing two different textbooks at the same time was excessive. In addition, we realized that we could incorporate the best features of Human Sexuality into Discovering Human Sexuality by judicious changes to the text and by the addition of two appendices containing more advanced “optional” material.
Features of Discovering Human Sexuality, Third Edition Important features of Discovering Human Sexuality distin- guish our book from competing texts:
evidence-based approach We believe that human sexu- ality is an academic subject like any other, meaning that it should be grounded in reason. Throughout the book, we have sought to present statements that are supported by data, ideas that are tested or testable, and recommendations that are based on research. There are many unanswered questions in sexuality, of course—questions about how ab- normal modes of sexual expression (paraphilic disorders) develop, for example, and how best to treat them. In deal- ing with these controversies, an evidence-based approach demands a nondogmatic style and a willingness to admit that not everything is known. Some students may feel chal- lenged to enter the field of sex research themselves in order to help fill those gaps in our understanding.
Some human sexuality texts contain a great deal of advice to students, especially in the area of relationships. Much of this advice has no objective basis and seems designed more to transmit the authors’ values than to foster an authentic learning experience. In Discovering Human Sexuality, we keep the total quantity of advice down and try to ensure that the advice we do give has been “field-tested.” Even in such an elementary matter as how to put on a condom, many texts include useless steps, such as squeezing the tip of the con- dom to leave space for the ejaculate. Doing so serves no pur- pose—the man who could burst a condom with his ejaculate has yet to be born—and neither the World Health Organiza- tion nor the leading U.S. experts believe that it should be part of the instructions for condom use. It has become an element in the folklore that gets perpetuated by textbooks— though not by this one.
Literature citations are, of course, an important element of an evidence-based book. We have been surprised by how cavalierly some competing books deal with this issue—quite commonly, citations in the text are not matched by any cor- responding entries in the bibliography. In Discovering Human Sexuality we have made every effort to ensure that references are fully documented. Another common practice that we consider unacademic is referring to original research stud- ies by citing magazine or newspaper articles that mention
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xxII PREFACE
them, rather than the journal articles in which the research was presented. Our policy has been to cite original sources wherever possible, and to use magazine and newspaper ref- erences for the kinds of topics they excel at, such as news stories, cultural trends, and the like.
emphasis on diversity Today’s college students come from a wide range of backgrounds, and in their adult lives they will have to deal with people very different from themselves. Our text presents this diversity in a detailed and nonjudgmental fashion. For example, with regard to sexual orientation, we go far beyond “gay,” “bisexual,” and “straight”: We talk about the ever-changing history of the butch-femme dichotomy in lesbian culture, women whose self-identity is too fluid for one-word labels, gay men who are “bears” or “bear cubs” or into the leather scene, what it’s like to be gay and Asian-American or Native American, how the gay experience differs for different generations of Americans and for gay people around the world, and so on. Similarly, we take pains to discuss racial, ethnic, and religious diversity, as they affect sexuality, and of course diversity in the actual modes of sexual behavior—includ- ing some of the more unusual forms of sexual expression such as “adult babies” and men whose partners are (liter- ally) dolls.
presentation style Simon LeVay, Janice Baldwin, and John Baldwin are all experienced authors of college text- books. In creating Discovering Human Sexuality, we have pooled our writing skills to ensure that the text is fully ac- cessible, engaging, and relevant to students of diverse back- grounds. The result of these combined efforts is, we believe, the most readable and student-friendly human sexuality text on the market.
art program Another way that we have striven to main- tain both comprehensibility and interest is through the illus- trations. One might think that it would be a simple matter to illustrate a book on human sexuality, but in reality it is a significant challenge. Illustrating some of the concepts dis- cussed in this book, especially in its more biologically orient- ed sections, requires a great deal of thought and design skill. Our publisher, Sinauer Associates, is an industry leader in the use of art as a pedagogical medium. Thanks to our pub- lisher’s efforts, many complex topics, such as the regulation of the menstrual cycle, have been given a visual representa- tion that gracefully parallels and clarifies the accompanying text. Nearly every two-page spread in the book offers one or more illustrations—photographs, drawings, diagrams, graphs, or charts—relevant to the text on that spread. Besides their informative value, illustrations offer important visual relief. Some of our competitors’ texts contain sequences of
up to ten pages without a single illustration—a definite chal- lenge to the average student’s attention span.
boxes The 76 boxes are an important feature of the book. The boxes are organized into eight themes: Controversies; Biology of Sex; Cultural Diversity; Research Highlights; Sexual Health; Sex in History; Personal Points of View; and Society, Values, and the Law. Within each theme, the sub- jects range from the serious to the lighthearted, but they all attempt to broaden the reader’s horizons with a more in- depth look at specific questions than is possible within the main text: What exactly does “losing one’s virginity” mean to today’s teenagers, behaviorally and emotionally? Is there more than one kind of female ejaculation? What’s it like to be a rubber fetishist? Why do some Amazonian peoples be- lieve that a child can have several fathers? In tackling these and many other questions, the boxes provide breaks from the steady flow of the text and allow students to consider specific issues in a more relaxed and informal way.
Other aids to learning and revision include key terms (indi- cated by boldfaced type and defined in a running glossary), FAQs (frequently asked questions), discussion questions, chapter summaries, Web resources, and recommended reading materials.
Discovering Human Sexuality’s student companion web- site (sites.sinauer.com/discoveringhumansexuality3e) is an invaluable learning aid. This site parallels the text with a thorough set of study questions, animations, activities, Web topics, quizzes, and other resources. Website activities are linked to the text and are referenced in maroon type in the printed text. In addition, a complete set of instructor supple- ments is available to qualified adopters of the textbook. See the section on Media and Supplements for details on the full range of material that accompanies Discovering Human Sexuality.
The Third Edition The following are examples of the many changes that we have made for the Third Edition: zz Chapter 1, “Sexuality: Pathways to Understanding,”
has been thoroughly rewritten. It now pays less attention to the history of sex research and more to the diversity of methods that are used to study sexu- ality. We discuss a specific example of the use of each methodological approach. zz We have added discussions of many topics that
were not covered, or only briefly covered, in earlier editions. These topics include group sex (Chapter 6); data-mining studies based on OkCupid and
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other websites (Chapters 5, 12, and elsewhere); the influence of physical attractiveness on men’s and women’s satisfaction with their long-term relation- ships (Chapter 5); the new definitions of paraphilias and paraphilic disorders in DSM-5 and the contro- versy surrounding them (Chapter 13); the current debate on how to respond vigorously and yet fairly to allegations of campus rape (Chapter 16); and the personalities and attitudes of men who use prosti- tutes (Chapter 17). We have also deleted numerous passages that seemed less interesting or instructive than they were a few years ago. zz We have added 19 new boxes on a wide range of
topics, including “Foot Orgasms,” “Pain-free Child- birth,” “Feticide,” “Why Gay Genes?” “STIs and the Law,” and “What’s It Like to Be a Porn Star?” zz We have of course taken the opportunity to update
the book with the latest research, surveys, statistics, laws, medical advances, contraceptive techniques, and cultural happenings. zz The two appendices cover material that was not
included in Discovering Human Sexuality, Second Edition. We present this material in the form of appendices so that instructors may include it or not as suits the purposes of their classes and the interests and backgrounds of their students. Appendix A is an abbreviated and updated version of the chapter “Sex and Evolution” from Human Sexuality, Fourth Edi- tion. It tackles important questions that are addressed in few other undergraduate human sexuality text- books, such as: What is the adaptive value of sexual reproduction? How does sexual selection work? What are the benefits and costs of male and female promiscuity? and What is the basis of incest avoid- ance? Appendix B lays out more detail on the role of the nervous system in sexual behavior and physiol- ogy than is presented in the main text, including, for example, the anatomy and functional role of the autonomic nervous system in genital responses.
Acknowledgments Producing a modern college textbook such as this one requires the combined efforts of a much larger team of professionals than the three of us who are privileged to have our names on the front cover. The staff members of Sinauer Associates have produced, with great efficiency and good humor, a textbook of outstanding visual quality and educational value. Those with whom we have had the most enduring contacts are editor Sydney Carroll, produc- tion editor Martha Lorantos, and photo researcher David
McIntyre, but many others labored behind the scenes to ensure the book’s high quality and timely production. We are especially grateful for the production oversight of Janice Holabird and Christopher Small, and for the creative cover design by Joan Gemme. We also thank Lou Doucette for her skillful copyediting; Jason Dirks, Carolyn Mailler, Mara Sil- ver, Suzanne Carter, Ann Chiara, Thomas Friedmann, and Nate Nolet for their work on the media and supplements package; Marie Scavotto, Nancy Asai, and Susan McGlew for their effective work promoting the book; Johanna Walko- wicz for obtaining outside reviews; and Penny Grant for sending us our checks on time!
Reviewers We acknowledge with gratitude the extensive and construc- tive comments made by the people who reviewed chapters of Discovering Human Sexuality for the new edition. These reviewers are listed below. Helpful comments have also come from the Baldwins’ students at the University of Cali- fornia, Santa Barbara.
Ernest Abel, Wayne State University Amy Beeman, San Diego Mesa College Kimberly Blackwell, Hampton University Elizabeth Calamidas, Richard Stockton College Michael Clayton, Youngstown State University Karen Gee, Mission College Samantha Gibeau, Lane Community College John Hallock, Pima Community College Julie Harris, East Carolina University Lynda Hoggan, Mt. San Antonio College Nathan Iverson, California State Polytechnic University, Pomona Jason Lavender, North Dakota State University Janet Lever, California State University, Los Angeles Vicki Lucey, Modesto Junior College Stephanie Marin, California State Polytechnic University, Pomona Wanda C. McCarthy, University of Cincinnati Clermont College Heather Meggers, Birmingham Southern College Tami James Moore, University of Nebraska at Kearney Peggy Oberstaller, Lane Community College Carolyn Peterson, University of Cincinnati Jason Rothman, California State Polytechnic University, Pomona Justine Shuey, Montgomery County Community College Peter Sparks, Oregon State University–Cascades Paul Vasey, University of Lethbridge James Vaughn, University of Science and Arts of Oklahoma
PREFACE xxIII
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Media and Supplements to accompany Discovering Human Sexuality, Third Edition
For the Student Companion Website sites.sinauer.com/discoveringhumansexuality3e
The Discovering Human Sexuality, Third Edition Companion Website includes a robust set of study and review aids—all available at no cost to the student. This online companion to the textbook takes the place of a printed study guide and includes the following resources: zz Chapter Outlines: Complete outlines of each chapter
provide an overview of the chapter and include links to the relevant Study Questions for each section. zz Chapter Summaries: A thorough review of each chap-
ter’s content. zz Learning Objectives: The objectives help focus the
student on the important concepts and topics in each chapter; each is referenced to specific textbook head- ings and pages. zz Activities: For selected chapters, animations, dynamic
illustrations, and labeling exercises help the student learn and understand complex concepts and ana- tomical (and other) terms. zz Study Questions: An extensive set of interactive self-
study questions covers the full range of content in every chapter. zz Flashcards: Students can quiz themselves on all the
important terms from each chapter, or they can browse the list of terms as a review. zz Web Links: A set of online sites and resources relevant
to each chapter. zz Glossary: A complete online version of the book’s
glossary. zz Online Quizzes: Two sets of questions are available
for each chapter, for instructors to assign or make available to students as review exercises (instructor registration required): zz Multiple-Choice Quizzes test student compre-
hension of the material covered in each chapter. zz Essay Questions challenge students to synthe-
size and apply what they have learned.
For the Instructor (available to qualified adopters)
Instructor’s Resource Library The Discovering Human Sexuality, Third Edition Instructor’s Resource Library (IRL) contains a wealth of resources for use in course planning, lecture development, and assessment. Contents include: zz Textbook Figures & Tables: All of the textbook’s figures
(both line art and photographs) are provided as JPEG files at two sizes: high-resolution (excellent for use in PowerPoint) and low-resolution (ideal for web pages and other uses). All the artwork has been reformatted and optimized for exceptional image quality when projected in class. zz PowerPoint Resources: Two ready-to-use presentations
are provided for each chapter: zz A lecture presentation that includes text cover-
ing the entire chapter, with selected figures. zz A figures presentation that includes all the fig-
ures and tables from the chapter. zz Instructor’s Manual: The Instructor’s Manual pro-
vides instructors with a variety of resources to aid in planning their course and developing their lectures. For each chapter, the manual includes a chapter overview, a chapter outline, the complete chap- ter summary, class discussion questions, teaching resources, and suggested readings. zz Media Guide: The Media Guide includes extensive
lists of suggested video segments (and full-length titles) that are ideal for use as lecture starters or other in-class activities. Video suggestions (with links and sources) are provided for topics across all chap- ters, and suggested discussion questions are also included. zz Test Bank: The Test Bank consists of a broad range of
questions covering all the key facts and concepts in each chapter. Each chapter includes multiple-choice, fill-in-the-blank, and, new for the Third Edition, short answer questions. Also included are all of the Companion Website quizzes (multiple-choice and essay), the textbook end-of-chapter questions, and
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MEDIA AND SUPPLEMENTS xxV
the Media Guide discussion questions. All questions are keyed to Bloom’s Taxonomy and referenced to specific textbook sections. zz Computerized Test Bank: The entire test bank is pro-
vided in Blackboard’s Diploma software. Diploma makes it easy to assemble quizzes and exams from any combination of publisher-provided questions and instructor-created questions. In addition, quiz- zes and exams can be exported to many different course management systems, such as Blackboard and Moodle.
Online Quizzing The Discovering Human Sexuality Companion Website fea- tures pre-built chapter quizzes (see above) that report into an online gradebook. Adopting instructors have access to these quizzes and can choose to either assign them or let students use them for review. (Instructors must register in order for their students to be able to take the quizzes.) Instructors also have the ability to add their own questions and create their own quizzes.
Value Options eBOOK Discovering Human Sexuality, Third Edition is available as an eBook, in several different formats. The eBook can be pur- chased as either a 180-day rental or a permanent (non-expir- ing) subscription. All major mobile devices are supported. For details on the eBook platforms offered, please visit www. sinauer.com/ebooks.
Looseleaf Textbook (ISBN 978-1-60535-379-1) Discovering Human Sexuality is available in a three-hole punched, looseleaf format. Students can take just the sec- tions they need to class and can easily integrate instructor material with the text.
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Discovering Human Sexuality
third edition
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1Chapter
Sexuality is a fundamental aspect of human nature.
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Sexuality: Pathways to Understanding
Sexuality is a central and all-pervasive theme of human existence. At its best, sexuality charges our lives with energy, excitement, and love. It offers a deep sense of connectedness, capable of spanning and healing social divisions. It creates family, the primary unit of society and the cradle of future generations.
At its worst, sexuality brings prejudice, anguish, violence, and disease. To begin our exploration of this powerful and mysterious force, we first
ask what the terms “sex” and “sexuality” mean and why sexuality is a topic worth studying. We go on to review some of the ways in which human sexuality has changed between the origin of our species and the present day. Our purpose is to make clear that, even though there may be some eternal truths about sexuality, it is not static: It changes slowly as a result of evolutionary forces, and much faster under the influence of culture. We then go on to describe the variety of methods by which sexuality can be studied, methods that will be applied repeatedly throughout the remainder of the book.
To do it justice, we must approach human sexuality with open minds, with respect for diversity, and with all the modes of inquiry that have been used to illuminate human nature. Approached in this way, the topic is not just another step in your college career: It is a personal voyage of discovery that will help you to enjoy the best that sexuality has to offer, and to avoid the worst.
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4 chapter 1
Sexuality Is a Broader Concept than Sex The term sex has two meanings. First, it means the distinction between female and male—a distinction that, as we’ll see in later chapters, is not as clear-cut as you might imagine. Second, it means engaging in sexual behaviors. These behaviors may be very obviously sexual because they are marked by genital phenomena such as vagi- nal lubrication, penile or clitoral erection, orgasm, and so on. But they also include behaviors that do not directly involve the genitals, such as courtship, as well as behaviors such as kissing that may or may not be sexual depending on context.
The term sexuality includes sex but also goes beyond it to encompass the entire realm of human experience that is more or less closely connected with sex. It means, for example, our gendered traits—the psychological traits that differ, to a greater or lesser extent, between women and men. It means our sexual and romantic attrac- tions and relationships—who we find attractive or fall in love with, and how we establish, maintain, or dissolve sexual partnerships. It means becoming a parent (or preventing that from happening). It also includes the two-way relationship between our personal sexual identities and behaviors and social structures such as the law, religion, medicine, and politics.
Studying Sexuality Has Practical Benefits There are many possible reasons why you have chosen to take a course in human sexuality. Maybe you’re simply curious about a topic that is often treated with embar- rassment, evasion, or flippancy. Maybe you are looking for ways to improve your own sex life, or you think you have sexual problems that need to be solved. Maybe you are planning a career that requires an understanding of human sexuality.
Regardless of your specific motives, many practical benefits are to be gained from taking this course and reading this textbook. Here are some examples:
zz Improving your understanding of the structure and function of your geni- tals and those of your partners will help you give and receive more plea- sure from sex. zz Learning more about how people communicate on sexual topics will
increase your chances of forming and maintaining satisfying relationships and avoiding abusive ones. zz Learning about sexual diversity will encourage you to be more under-
standing of unusual sexual desires and behaviors—whether in others or in yourself. zz Educating yourself about contraception and sexually transmitted infections
will lessen the chance that your sexual behavior may end up harming you or your partners. zz Becoming knowledgeable about sex will be an asset to you in your future
career—most especially if you enter the medical or helping fields, but also in any career that brings you into contact with other people. zz Educating yourself about sex will enable you to educate others—including
your friends and your own children, if you plan to have them. zz By learning to think critically about research, you will become a more
discriminating consumer of media reports and advertising relating to sexuality.
Sexuality Has Changed over Time Most—but not all—women and men experience sexual desire and engage in sexual relationships at some point in their lives. This has likely been true across the course of
sex A person’s identity as female or male, or sexual behavior.
sexuality The feelings, behaviors, and identities associated with sex.
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Sexuality: pathwayS to underStanding 5
human history and prehistory, and it is true around the world today. But the ways in which these desires and relationships express themselves have been extraordi- narily varied. Here we sketch some of the changes that have occurred over time.
Sexuality has been influenced by evolution Humans evolved from the common ancestors of humans and nonhuman pri- mates, who lived about 7 million years ago. You might think that we could get some idea of early human sexuality by studying the sexual behavior of our clos- est relatives, the great apes (chimpanzees, bonobos, gorillas, and orangutans), on the assumption that these animals have changed less over time than we have.
It turns out, however, that there is a great deal of sexual diversity even among these closely related species. Among chimpanzees, for example, most sexual behavior is between males and females and has the potential to lead to preg- nancy. Among bonobos, which look very similar to chimpanzees, sexual contact between individuals of the same sex is common. The function of such behavior is clearly not reproductive; rather, it serves the purposes of conflict resolution and alliance formation (Parish & de Waal, 2000). Among orangutans coercive sex—analogous to rape in humans—is common (Knott et al., 2010), but that’s not true for bonobos. Some of these species differences are described in Appendix A.
One general characteristic of sexual behavior among our primate relatives is that more of it takes place than is strictly necessary for reproductive purposes—some- times a great deal more. Another is that individuals compete for sex partners: Males often compete for access to the most fertile females, while females often compete for the attention of high-ranking males. You don’t have to be a sex researcher to know that these kinds of competition are prevalent in our own species today. It’s likely that competition for partners has characterized sexuality throughout human history and prehistory, and that this competition has driven the evolution of sex differences in appearance and behavior.
Early in the evolution of our species, humans probably lacked understanding of the connection between coitus (penile-vaginal intercourse) and reproduction. Of course, they acted as if they understood, just as our primate relatives do, but their sexual behavior was actually driven by instincts that required little conscious aware- ness. Even today, there are human cultures where people are unaware of biological facts that seem obvious to us, such as the fact that a child has just one father, or that pregnancy and childbirth result from a single act of coitus (Box 1.1).
Over the course of human history the trend toward an increasingly conscious understanding of how sex “works” has influenced human sexuality in directions that seem counterintuitive in evolutionary terms. For example, the knowledge that the deposition of semen (the male ejaculate) in the vagina is what causes pregnancy led to the introduction of contraceptive practices. These included withdrawal of the penis prior to ejaculation—a practice known already in Old Testament times—and the use of various kinds of barriers placed in the vagina. Similarly, methods intended to interrupt an established pregnancy—by use of certain herbs or poisons, or by black magic—were widely used in the Middle Ages, with varying success. As methods for contraception and abortion have improved over the centuries, so has it become increasingly possible to enjoy the pleasures of sex without its natural consequences. This has undoubtedly increased people’s—especially women’s—willingness to engage in sex both within and outside of established relationships.
Society has changed sexuality Human sexuality has been greatly influenced by the development of social controls. The transition from a hunter-gatherer lifestyle to one of settled agriculture took place coitus Penile-vaginal intercourse.
Male primates, such as these golden snub-nosed monkeys, often fight over access to females.
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in the Middle East roughly 10,000 years ago. This transition led eventually to the formation of city-states, which required governments and the regulation of social behavior. Nudity was restricted, in part with the aim of reducing sexual arousal, pre- venting the sight of sexual arousal in others, and eliminating sexual conflicts. (Some present-day hunter-gatherer cultures still permit nudity.) Marriage was formalized, and nonmarital sex was discouraged to a greater or lesser degree.
Meet My Dads no matter how many men a woman has sex with, any child she bears has only a single biological father—the man whose sperm fertilized the woman’s ovum. in most cultures around the world, people accept this reality of single paternity. yet anthropologists have discovered an exception among many of the indigenous tribal societies of lowland South america (amazonia and nearby areas). here people believe that a man’s semen remains in the woman’s body indefinitely after sexual intercourse, so if several different men have sex with her before she becomes pregnant, then all of them contribute to the making of her child (Becker- man & Valentine, 2002).
this belief is called partible paternity (“divisible fatherhood”). By studying language relationships among the societies where partible paternity is found, anthropologist robert walker of the university of Missouri and his colleagues have traced it back to the distant past, probably to the time when the lowlands were first settled and the settlers spoke a common language (walker et al., 2010).
what benefit does the concept of partible paternity confer? anthropologists such as william crocker of the Smithsonian institution have found that the societies that believe in parti- ble paternity engage in distinctive sexual practices (crocker & crocker, 2003). they may participate in rituals in which women engage in sex sequentially with multiple men. and unlike in other cultures, where men typically guard their wives from sexual con- tact with other males, men in these amazonian tribes may freely offer their wives to male relatives as well as to powerful men who are actual or potential allies.
partible paternity, and the practices associated with them, benefit women’s efforts to raise children. that’s because the multiple “fathers” of a given child may give gifts in exchange for sex, may support or protect the child, or may at least refrain from killing the child. (the killing of infants and children by men has traditionally been a significant cause of mortality in ama- zonian cultures.)
what about the men? on the face of it, the notion of par- tible paternity seems to disadvantage them, because they may
end up supporting children who are not biologically theirs. on the other hand, they are “hedging their reproductive bets” by spreading their semen widely. this may be of particular value to high-status men, who gain disproportionate access to other men’s wives, thanks to partible paternity. in addition, partible paternity gives men some assurance that their biological chil- dren will have male support in the event of their own premature death, something that’s all too common in amazonia.
this still leaves unanswered the question of why partible paternity is common in lowland South america but rare else- where. the answer may be related to the importance of kin- ship and alliances in those societies, combined with a general absence of material wealth. in such circumstances paternity may be used as a unit of wealth that can be traded, as it were, in social networks.
partible paternity the belief that two or more men may be fathers of the same child.
This Araweté woman of Brazil may believe that two or more men fathered her son.
Box 1.1 Cultural Diversity
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Organized religion played a role in these changes (Endsjo, 2011). Although religious teachings have varied greatly, they have often fostered procreative heterosexual sex within marriage while labeling other forms of sexual expression as sinful. This was particularly true for the Christian religion: For most of the two millennia since its foundation, Christian teachings forbade all nonmarital sex, homo- sexual sex, masturbation, contraception, abortion, and polygamy. Even marital sex was restricted to coitus in certain positions, and it was forbidden on certain days of the week and during Lent (Ranke-Heinemann, 1990). Priests were commonly barred from marriage or any kind of sexual activity. This changed to some extent after the Reforma- tion, when western Christianity splintered into numerous denominations, some of which have become much more liberal in the area of sexual ethics compared with the Catholic Church.
The development of large-scale societ- ies led to the emergence of class structures, with the rich and powerful at the top and the impoverished masses at the bottom. What class you belonged to greatly influenced your sex life. Take India: The Kama Sutra, compiled around the 2nd century, describes innumerable ways for men to obtain sexual pleasure and to give sexual pleasure to women (Vatsyayana, 1991) (Figure 1.1). It also describes sex between women and between men. But the Kama Sutra was written for and about the idle rich. (What to do between breakfast and lunch? Teach your parrot to talk.) If the sex lives of low- caste Indians were anything like they are today, they involved hasty, fully-clothed couplings with the minimum of pleasure or romance (Nath & Nayar, 1997).
Another way that class influenced sexuality had to do with polygamy. The major- ity of human cultures have permitted men to have more than one wife, but it was largely rich and powerful men who did so, because they had sufficient means—King Solomon is said to have had a thousand wives. Polygamy reduced the numbers of available women and thus made it harder for poor men to afford even one wife. What’s more, polygamy is connected with the idea that women are men’s property— if a rich man has many cattle, why shouldn’t he have many wives? By banning polyg- amy, the Christian religion promoted a somewhat more gender-equitable society.*
Across history, large numbers of men have been deprived of a sex life altogether by being castrated—that is, by having their testicles removed, and sometimes the penis also. Such men were called eunuchs. Castration was carried out as a punish- ment among criminals or prisoners of war, or (if done before puberty) to produce asexual male slaves who could serve certain roles such as court attendants, harem guards, dancers, or singers. Some eunuchs achieved powerful positions in imperial courts across Asia. In India, some men were (and still are) voluntarily castrated as an initiation into the transgender religious caste known as hijras, who are described further in Chapter 4 (Nanda, 1998).
Figure 1.1 The Kama Sutra describes a wide variety of sexual positions.
* In early Islam, polygamy helped provide for the many women whose husbands died in warfare.
heterosexuality Sexual attraction to, or behavior with, persons of the opposite sex.
homosexuality Sexual attraction to, or behavior with, persons of the same sex.
polygamy Having more than one spouse at the same time, as a social institution.
castration Removal of the testicles or testicles and penis.
eunuch A man who has been castrated.
transgender (or trans) Identifying with the other sex or rejecting gender norms.
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In general, castration has served the interests of noncastrated men, especially powerful men, and it therefore represents another way in which class and sexuality interact. Today, castration by surgery or “chemical castration” by drugs is performed voluntarily on some men with prostate cancer in an effort to prolong their lives—per- haps a quarter of a million American men are in this situation (Wassersug et al., 2014).
Another important effect of cultural change has involved sexually transmitted infections. When people lived in small groups and stayed in a restricted area, they tended to reach a biological accommodation with the infectious agents (bacteria and viruses) present in that population, such that their effects were not especially severe. Increases in population density and long-distance travel changed this picture: The organism that causes syphilis, for example, was present in the native populations of the Americas long before the arrival of Columbus and other explorers, but when these men returned to Europe, bringing the organism with them, it unleashed a dev- astating epidemic (Rothschild et al., 2000). Potentially fatal diseases such as syphilis and (more recently) AIDS made sex itself seem frightening and sinful.
Marriage has been transformed Yet another important change has been the radical decline in birth rates that has taken place in most countries, starting in the late 18th century. Over this period the number of children born to the average American woman has fallen from 7 or 8 to about 2 (Figure 1.2). Today, there are plenty of women or couples who choose to have no children at all—something that used to be quite unusual, except for women in religious orders. This decline has not been accompanied by any decline in people’s interest in sex. Thus the idea has gained currency that sex has a legitimate emotional or recreational function, beyond the production of children.
The institution of marriage has changed over time (Abbott, 2011). In many tradi- tional societies marriage signified the transfer of ownership of a woman from her father to her husband; marriages were negotiated and often involved large bridal payments. People fell in love, but they were lucky if they married the people they fell in love with. In Europe and America, even as late as the 19th century, a suitor was expected to ask the girl’s father for permission to propose to her, and if permis- sion was refused—because the young man had insufficient means, for example—the young couple’s only recourse might be to run away (elope) and marry at some distant location.
A woman was expected to be a virgin when she married, but a man could be forgiven or even admired for “sowing his wild oats.” (This was an example of the double standard, by which males and females were, and still may be, held to differ- ent moral codes.) The husband’s and wife’s roles in marriage were also quite distinct:
double standard The idea that acceptable behavior is different for men than for women.
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The husband was the breadwinner, the wife the homemaker and child rearer, perhaps with the help of servants.
Before the 20th century, marriage was for life: Divorce was quite uncommon and was only permitted in cases of proven adultery. Divorce laws were greatly liberalized over the course of the 20th century, and now nearly half of all U.S. marriages end in divorce rather than death (Wilcox & Marquardt, 2011). What’s more, it’s now widely accepted that women are sexually active before mar- riage, and that couples may live together (cohabit) before mar- riage or without marrying at all. And the birth of children outside of marriage, once a shocking secret, is now more or less routine: Over 40% of all U.S. births are now to unmarried women, who may be single or cohabiting with a man or with a woman (Martin et al., 2013).
Up until the mid-20th century the vast majority of Americans considered inter- racial marriage to be sinful, and such marriages were illegal in many states. Atti- tudes changed gradually after World War II, and in 1967 the U.S. Supreme Court established a constitutional right to marry across racial lines (Figure 1.3). Currently we are witnessing a similar trend with regard to same-sex marriage, but gay couples who marry today are joining an institution that has lost a great deal of its former significance.