Wayne State University Law Faculty Research Publications Law School 1-1-1995 Sex and Temperament in Modern Society: A Darwinian View of the “Glass Ceiling” and the “Gender Gap” in Compensation Kingsley R. Browne Wayne State University Recommended Citation Browne, Kingsley R. Sex and Temperament in Modern Society: A Darwinian View of the “Glass Ceiling” and the “Gender Gap” in Compensation. 37 Ariz. L. Rev. 971 (1995) Available at: https://digitalcommons.wayne.edu/lawfrp/147 This Article is brought to you for free and open access by the Law School at DigitalCommons@WayneState. It has been accepted for inclusion in Law Faculty Research Publications by an authorized administrator of DigitalCommons@WayneState. Articles SEX AND TEMPERAMENT IN MODERN SOCIETY: A DARWINIAN VIEW OF THE GLASS CEILING AND THE GENDER GAP Kingsley R. Browne* Table of Contents I. Introduction ............................................................................... 973 II. Sex Differences and Evolutionary Theory ..................................... 985 A. Natural Selection and Evolutionary Psychology ..................... 985 B. Evolution of Temperamental Sex Differences ....................... 990 C. Evidence of Differential Reproductive Strategies in Our Evolutionary Past ................................................... 1000 D. Evidence for the Continued Existence of the Evolved Psychological Mechanism ...................................... 1006 III. Biological Sex Differences in Risk-Taking, Status- Seeking, Aggressiveness, and Nurturance ..................................... 1016 A. Behavioral and Temperamental Sex Differences ................... 1017 1. Aggressiveness, Dominance-Assertion, Competitiveness, Achievement Motivation, and Status-Seeking ........................................................ 1017 2. Risk-Taking ................................................................. 1028 3. Nurturance, Empathy, and Interest in Others .................. 1033 B. Evidence for a Biological Basis for Temperamental Sex D ifferences ................................................................. 1037 1. Behavioral Genetics ...................................................... 1038 2. Hormones and Behavior ................................................ 1040 a. The Organizing Effect of Hormones on Developing Fetuses .................................................. 1043 b. The Activational Effect of Circulating Hormones ....... 1047 C. Socialization Is an Inadequate Explanation for Sex D ifferences ....................................................................... 1050 * Associate Professor, Wayne State University Law School. © 1995 Kingsley R. Browne. The author would like to thank Cynthia Browne, David Buss, John Dolan, Joseph Grano, Owen Jones, Ariel Levi, Bobbi Low, Michael McIntyre, Ralph Slovenko, and Lionel Tiger for their valuable comments on an earlier draft of this article, as well as the participants in a faculty workshop at Benjamin N. Cardozo Law School. The author has also greatly benefited from discussions at the Conference on Law, Biology, and Human Behavior sponsored by the Gruter Institute for Law and Behavioral Research. 972 ARIZONA LAW REVIEW [Vol. 37:971 IV. The Glass Ceiling and the Gender Gap ......................................... 1064 A . The Glass Ceiling .............................................................. 1064 B. The Gender Gap in Compensation ....................................... 1075 C. The Feminist Critique of the Status of Women in the W orkplace ........................................................................ 1083 1. The Argument that Women Are Disadvantaged by Current Workplace Structures that Force Them to Choose Between Work and Family ................................. 1083 2. The Argument that Women Must Make Choices that M en Have Never Faced ................................................. 1092 3. The Argument that Underrepresentation of Women in Particular Jobs Demonstrates Discrimination ............... 1099 V . Conclusion ................................................................................ 1101 1995] SEX AND TEMPERAMENT 973 [I]f social inequality based on sex is a serious problem, and if we really intend to do something constructive about it, we are going to need a comprehensive understanding of its causes. I am convinced that we will never adequately understand the present causes of sexual asymmetry in our own species until we understand its evolutionary history in the lines from which we descend.1 I. INTRODUCTION Human beings are animals. As such, we-like all other living things- have been shaped over the course of our history by the forces of natural selection. 2 At one level, such an assertion is largely uncontroversial. We understand that the reason that humans have a bipedal form of locomotion is that bipedalism was adaptive in the past and presumably remains so in the present. Scientists may differ about the particular reasons that bipedal locomotion became established in our species, but few doubt that it was a product of natural selection. Although there may be theological objections to the general notion that humans have been shaped by natural forces and scientific disputes about the precise course that natural selection has taken us, the scientific case for the proposition that humans have evolved according to the principles of natural selection is overpowering. 3 What does appear controversial in some quarters, however, is the suggestion that natural selection has presided over not only the morphological evolution of humans but over our psychological evolution as well. Yet the mechanisms that shape human behavior, no less than those that shape human anatomy and physiology, must be a product of the fundamental laws of biology. This is not a claim that we are genetically programmed automatons and that the environment "doesn't matter." It matters a great deal, but the environment per se "is powerless to act on the psyche of an animal, except in ways specified by the developmental programs and psychological mechanisms that already happen to exist in that animal at a given time."4 Over the last three decades, theoretical and empirical work in biology, psychology, and anthropology has provided powerful support for the conclusion that, to a much greater extent than is typically recognized, human behavioral tendencies are shaped by our biology. Everyone recognizes, of course, that the reason that humans do not (usually) behave like chimpanzees is that we are not chimpanzees, but there seems to be an underlying assumption that chimpanzees act the way they do because they are chimpanzees and humans act the way they do because they choose to.5 There is a grain of truth in this 1. SARAH B. HRDY, THE WOMAN THAT NEVER EVOLVED 14-15 (1981). 2. MARTIN DALY & MARGO WILSON, SEX, EVOLUTION, AND BEHAVIOR 279 (2d ed. 1983). 3. See generally TIMOTHY H. GOLDSMITH, THE BIOLOGICAL ROOTS OF HUMAN NATURE: FORGING LINKS BETWEEN EVOLUTION AND BEHAVIOR (1991). 4. John Tooby & Leda Cosmides, On the Universality of Human Nature and the Uniqueness of the Individual: The Role of Genetics andAdaptation, 58 J. PERSONALITY 17, 21 (1990). 5. See Carl N. Degler, Danvinians Confront Gender; or, There Is More to It than History, in THEORETICAL PERSPECTIVES ON SEXUAL DIFFERENCE 33, 37 (Deborah L. Rhode ed., 1990) [hereinafter THEORETICAL PERSPECTIVES] (noting that "[a]Imost all modem students of human behavior give lip service to the Darwinian principle that human beings are included in the process of evolution through natural selection, but in practice many see a sharp disjunction between animals and human beings when they try to account for human behavior"). 974 ARIZONA LAW REVIEW [Vol. 37:971 assumption, since humans almost certainly have greater conscious control over their behavior than do chimpanzees. Although there is a tendency to envision a sharp break between animals and humans-viewing the behaviors of animals as largely fixed by biology and the'behaviors of humans as largely independent of biology-students of behavior now reject that sharp dichotomy, believing that animal behavior is more environmentally sensitive and human behavior more biologically influenced than previously believed. 6 It is time to acknowledge that the assumption that our behavioral repertoire is unconstrained by our fundamental nature7 is certainly wrong. Although it is conceivable, for example, that the state could forbid all sexual behavior, it could not forbid sexual desire, and given the strength of that desire it is extraordinarily doubtful that any society, no matter how totalitarian, could effectively forbid the behavior. The idea of a fundamental "human nature" is resisted by many,8 apparently out of concern that recognition of biological roots of human nature would deny the autonomy and dignity of the individual.9 But to say that there is an underlying "psychic unity of mankind" is not to deny individual difference or personal autonomy. Indeed, the concept of such a unity had its origins in liberal notions of fundamental human equality. Many also have political objections to the idea of a fundamental human nature, fearing that appeals to a biological human nature are merely a subterfuge to maintain the status quo.0 Nonetheless, an understanding of why we are the way we are is a precondition to our becoming the way that we hope to be. An understanding of human behavior and psychology may illuminate many public policy issues. One of the thorniest sets of issues facing our society today is