Why Sex Matters: A Darwinian Look At Human Behavior.

WHY SEX MATTERS WHY SEX MATTERS A Darwinian Look at Human Behavior Bobbi S. Low princeton university press princeton, new jersey Copyright © 2000 by Princeton University Press Published by Princeton University Press, 41 William Street, Princeton, New Jersey 08540 In the United Kingdom: Princeton University Press, Chichester, West Sussex All Rights Reserved Library of Congress Cataloging-in-Publication Data Low, Bobbi S. Why sex matters : a Darwinian look at human behavior / Bobbi S. Low. p. cm. Includes bibliographical references. ISBN 0-691-02895-8 (alk. paper) 1. Human evolution. 4. Sociobiology. GN281.4.L68 2. Sex role. 3. Nature and nurture. I. Title. 1999 305.3—dc21 99-24612 This book has been composed in Palatino Typeface The paper used in this publication meets the minimum requirements of ANSI/NISO Z39.48-1992 (R1997) (Permanence of Paper) http://pup.princeton.edu Printed in the United States of America 10 9 8 7 6 5 4 3 2 1 F OR MY SON MICHAEL, and for my academic lineage: parental, sibling, and offspring generations Contents xiii Preface xvii Acknowledgments 3 1. Introduction 4 Vampire Stories and Beyond 6 Explaining Behavior without Folklore 9 Kinds of “Why” Questions 11 Simple Rules, Complex Outcomes 12 Humans as Critters 19 2. Racing the Red Queen: Selfish Genes and Their Strategies 23 Whose Genes Count, and Why? Kin Selection 27 Summing Up the Basics: Assumptions and Objections 31 Novel Evolutionary Environments: Can the Principles Still Hold? 33 More than Ants or Peacocks: Lifetimes, Culture, Ecology, and Variation 35 3. The Ecology of Sex Differences 37 Sex and Strategies 44 The Ecology of Being Male and Female 47 Mating Effort viii CONTENTS 52 Parental Effort 53 Variance in Reproductive Success: Mating versus Parental Strategists 57 4. Sex, Status, and Reproduction among the Apes 58 The Ecology of Dominance and RS in Primates 60 Ecological Aspects of Mating Systems 62 Sex, Resources, and the Ecology of Human Reproduction 66 The Ecology of Human Mating Systems 74 The Ecology of Monogamy and Polyandry 77 5. Sex, Resources, Appearance, and Mate Choice 78 What Men and Women Want 83 Beauty, Resources, and Mate Choice 84 Signals of Desirability and Their Manipulation 88 Who Can Choose? 92 6. Sex, Resources, and Human Lifetimes 95 Starting Out: Resource Striving in the Womb 96 What’s a Mother to Do? Optimizing Maternal Effort among Offspring 98 Conflicts of Interest: Abortion, Infanticide, Abandonment, Neglect 102 Sex Differences in Reproductive Lifetimes 110 Sex Differences in Senescence 113 7. Sex and Resource Ecology in Traditional and Historical Cultures 113 Sexual Divisions of Labor 115 Sex and Control of Resources CONTENTS 116 Men, Women, and Resources in Traditional