Human sexuality

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: [email protected] 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

00_DHS3E_Frontmatter2.indd 6 1/20/15 12:27 PM

mailto:[email protected]
http://www.sinauer.com
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

00_DHS3E_Frontmatter2.indd 7 1/20/15 12:27 PM

http://www.SexInfoOnline.com
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

00_DHS3E_Frontmatter2.indd 8 1/20/15 12:27 PM

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