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Female and male brains are different, thanks to hormones coursing through the brain before birth. That’s taught as fact in psychology textbooks, academic journals, and bestselling books. And these hardwired differences explain everything from sexual orientation to gender identity, to why there aren’t more women physicists or more stay-at-home dads. In this compelling book, Rebecca Jordan-Young takes on the evidence that sex differences are hardwired into the brain. Analyzing virtually all published research that supports the claims of “human brain organization theory,” Jordan-Young reveals how often these studies fail the standards of science. Even if careful researchers point out the limits of their own studies, other researchers and journalists can easily ignore them because brain organization theory just sounds so right. But if a series of methodological weaknesses, questionable assumptions, inconsistent definitions, and enormous gaps between ambiguous findings and grand conclusions have accumulated through the years, then science isn’t scientific at all. Elegantly written, this book argues passionately that the analysis of gender differences deserves far more rigorous, biologically sophisticated science. “The evidence for hormonal sex differentiation of the human brain better resembles a hodge-podge pile than a solid structure…Once we have cleared the rubble, we can begin to build newer, more scientific stories about human development.” (20101203)
E-Book Content
Brain Storm
Brain Storm The Flaws in the Science of Sex Differences
REBECCA M. JORDAN-YOUNG
HARVARD UNIVERSITY PRESS Cambridge, Massachusetts London, England 2010
Copyright © 2010 by the President and Fellows of Harvard College All rights reserved Printed in the United States of America Library of Congress Cataloging-in-Publication Data Jordan-Young, Rebecca M., 1963– Brain storm : the flaws in the science of sex differences / Rebecca M. Jordan-Young. p. cm. Includes bibliographical references and index. ISBN 978–0–674–05730–2 (cloth : alk. paper) 1. Brain—Sex differences. I. Title. QP81.5.J67 2010 612.8′2—dc22 2010010165
For Sal
Contents
Preface
ix
1
Sexual Brains and Body Politics
2
Hormones and Hardwiring
3
Making Sense of Brain Organization Studies
4
Thirteen Ways of Looking at Brain Organization
5
Working Backward from “Distinct” Groups
6
Masculine and Feminine Sexuality
7
Sexual Orienteering
144
8
Sex-Typed Interests
198
9
Taking Context Seriously
10
Trading Essence for Potential Notes
293
References
339
Acknowledgments Index
383
379
1 21
237 269
109
41 65 91
Preface
Most books set out to answer questions. This book sets out to question answers. The answers I question have to do with the nature and causes of differences between men and women, and between straight people and gay people. Specifically, I question what we “know” about male and female brains, or gay and straight brains. When Simon LeVay reported in 1991 that he had found a difference in brain structure between gay and heterosexual men, which was trumpeted as the discovery of “The Gay Brain,” I found it interesting but also puzzling. How could gayness take a single identifiable form in the brain when it takes such varied forms in people’s lives? At the time, I had already been engaged for several years in large-scale sexuality research related to the AIDS epidemic. In an outreach storefront in Washington, DC, I ran a project that focused on injection drug users. It was there that I first met a lot of gay men. These men were not the pos