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Evolution's Rainbow

Evolution's Rainbow: Diversity, Gender, and Sexuality in Nature and People

Joan Roughgarden
Copyright Date: 2013
Edition: 1
Pages: 496
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  • Book Info
    Evolution's Rainbow
    Book Description:

    In this innovative celebration of diversity and affirmation of individuality in animals and humans, Joan Roughgarden challenges accepted wisdom about gender identity and sexual orientation. A distinguished evolutionary biologist, Roughgarden takes on the medical establishment, the Bible, social science-and even Darwin himself. She leads the reader through a fascinating discussion of diversity in gender and sexuality among fish, reptiles, amphibians, birds, and mammals, including primates.Evolution's Rainbowexplains how this diversity develops from the action of genes and hormones and how people come to differ from each other in all aspects of body and behavior. Roughgarden reconstructs primary science in light of feminist, gay, and transgender criticism and redefines our understanding of sex, gender, and sexuality. Witty, playful, and daring, this book will revolutionize our understanding of sexuality.Roughgarden argues that principal elements of Darwinian sexual selection theory are false and suggests a new theory that emphasizes social inclusion and control of access to resources and mating opportunity. She disputes a range of scientific and medical concepts, including Wilson's genetic determinism of behavior, evolutionary psychology, the existence of a gay gene, the role of parenting in determining gender identity, and Dawkins's "selfish gene" as the driver of natural selection. She dares social science to respect the agency and rationality of diverse people; shows that many cultures across the world and throughout history accommodate people we label today as lesbian, gay, and transgendered; and calls on the Christian religion to acknowledge the Bible's many passages endorsing diversity in gender and sexuality.Evolution's Rainbowconcludes with bold recommendations for improving education in biology, psychology, and medicine; for democratizing genetic engineering and medical practice; and for building a public monument to affirm diversity as one of our nation's defining principles.

    eISBN: 978-0-520-95797-8
    Subjects: Ecology & Evolutionary Biology

Table of Contents

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  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-viii)
  3. Preface to the 2013 Edition
    (pp. ix-xii)
    Joan Roughgarden
  4. Preface to the 2009 Edition
    (pp. xiii-xvi)
  5. INTRODUCTION: Diversity Denied
    (pp. 1-10)

    On a hot, sunny day in June of 1997, I attended my first gay pride parade, in San Francisco. The size of the crowd amazed me. As I marched from Civic Center up Market Street to San Francisco Bay, a throng of onlookers six persons deep on both sides shouted encouragement and support. For the first time, I felt the sheer magnitude of the gay community.

    I stored this impression in the back of my mind. How, I wondered, does biology account for such a huge population that doesn’t match the template science teaches as normal? When scientific theory says...


    • 1 Sex and Diversity
      (pp. 13-21)

      All species have genetic diversity—their biological rainbow. No exceptions. Biological rainbows are universal and eternal. Yet biological rainbows have posed difficulties for biologists since the beginnings of evolutionary theory. The founder of evolutionary biology, Charles Darwin, details his own struggle to come to terms with natural variation in his diaries fromThe Voyage of the Beagle

      In the mid 1800s, living species were thought to be the biological equivalent of chemical species, such as water or salt. Water is the same everywhere. Countries don’t each have water with a unique color and boiling temperature. For biological species, though, often...

    • 2 Sex versus Gender
      (pp. 22-29)

      To most people, “sex” automatically implies “male” or “female.” Not to a biologist. As we saw in the last chapter, sex means mixing genes when reproducing. Sexual reproduction is producing offspring by mixing genes from two parents, whereas asexual reproduction is producing offspring by one parent only, as in cloning. The definition of sexual reproduction makes no mention of “male” and “female.” So what do “male” and “female” have to do with sex? The answer, one might suppose, is that when sexual reproduction does occur, one parent is male and the other female. But how do we know which one...

    • 3 Sex within Bodies
      (pp. 30-42)

      Although the binary in gamete size is practically universal, the way male and female functions are packaged into individual bodies does not fit into any consistent polarity. We tend to think that males and females must be in separate bodies because most of us are, as are most of the animals we live with, such as our pets, domesticated stock, and the birds and bees around our parks. However, many species have other ways of organizing sexual functions.

      An individual body who makesbothsmall and large gametes at some point in life is called a hermaphrodite. An individual who...

    • 4 Sex Roles
      (pp. 43-48)

      Even species thought of as typical, with one gender per sex and individuals who maintain a single sex throughout life, often have gender roles quite different from the traditional template. Indeed, in some species, males (apart from making sperm) look and behave much as females do in other species, and females (apart from making eggs) look and behave much as males do in other species. If these species could express their thoughts about us, they would describe our gender distinctions as reversed.

      Anglerfish are deep-sea fish who have what looks like a tiny fishing pole attached to their head. A...

    • 5 Two-Gender Families
      (pp. 49-74)

      Let’s move on now to species with two genders that don’t change sex, do not have intersexual body parts, and aren’t sex-role reversed. Are such animals “normal”? Have we come at last to the familiar gender roles performed by ordinary bodies, as depicted on nature shows? Or are nature shows perhaps not telling the whole story? What goes on in two-gender animal families, and how are such families organized?

      Many of us were raised to admire the nuclear family as a norm and were taught that single-parent families, families of same-sex couples, or communes were second-best alternatives or, even worse,...

    • 6 Multiple-Gender Families
      (pp. 75-105)

      The social roles of multiply gendered animals are indicated by their bodies. Males or females in a species may come in two or more sizes or colors. The morphological differences are the tip of the iceberg. The two morphs approach courtship differently, have different numbers of mates, have different arrangements of between-sex and same-sex relationships, live different life spans, prefer different types of real estate for their homes, exercise different degrees of parental care, and so on. Because body shape, color, and posture—the important modes of communication in fish and lizards—are so easily visible to biologists, multigender societies...

    • 7 Female Choice
      (pp. 106-126)

      As further evidence of the difficulties with sexual selection theory, let’s consider how real-life female choice differs from female choice in Darwin’s sexual selection theory. Darwin focuses on mating only. A female is supposed to select males according to their attractiveness and prowess. Males are supposed to compete among themselves for mating opportunities and to advertise their good looks to females. This peculiar emphasis on the mating act alone is simply not supported by actual female choices, which are more concerned with the totality of reproduction, including the growth and protection of the young.

      “Darwinian fitness” is a technical term...

    • 8 Same-Sex Sexuality
      (pp. 127-158)

      The final nail in the coffin of Darwin’s sexual selection theory is the discovery of extensive same-sex sexuality in nature. According to Darwin, homosexuality is impossible because the purpose of mating is to transfer sperm with the intention of producing offspring, and a homosexual mating can’t produce offspring. So, if homosexuality is discovered, and if one also wishes to retain sexual selection theory, some fancy footwork is needed. Typically, biologists quickly assert that homosexuality is an “error” or, if not an error, then some devious and unsavory trick. On the other hand, if matings serve as much to manage relationships...

    • 9 The Theory of Evolution
      (pp. 159-182)

      Diversity in gender expression and sexuality undercuts Darwin’s theory of sexual selection. Saying this, however, does not meanallof Darwin’s writings are incorrect. Indeed, I feel we should not lose sight of his overwhelming contribution, even though I believe one of his theories is seriously mistaken.

      Perhaps Darwin’s most important discovery is that all species are related to all other species through shared descent from common ancestors. The most grand and most lowly share in the unity of life. Darwin came to this insight as a young man, during his travels as a naturalist on a sailing ship called...


    • 10 An Embryonic Narrative
      (pp. 185-195)

      Many developmental mechanisms must exist to produce the diversity of bodies, gender expressions, and sexualities so evident among the animals we’ve just visited. What are these mechanisms? How do two fertilized eggs that start out looking just about the same wind up producing two adults as different as a lion and a lioness, or a man and a woman? How does one fertilized egg grow up to become a corporate CEO, while another grows up to be a drag queen? This part of the book is about the developmental mechanisms that bring about diversity.

      The story of development is told...

    • 11 Sex Determination
      (pp. 196-206)

      The single biggest difference among people is sex—traits related somehow to the size of the gametes they make. Yet the overall difference between human males and females is moderate compared to other vertebrates. Mice males and females are nearly identical, except for gamete size and related genital plumbing, whereas lions have conspicuous male/female differences. Other than gamete size, our statistically valid sex differences are few and small, and our distributions overlap extensively. How do such differences between males and females develop?

      Accounts of how male and female differences develop in mammals usually begin with gonadal differentiation—the genes that...

    • 12 Sex Differences
      (pp. 207-237)

      Suppose now that a baby’s sex has been determined—the baby’s gene committee has met during early development and somehow managed to come to a decision. What next? How does development continue? Will all males graduate from uterine school wearing the same coat and tie, and all females the same dress? Obviously not. How much biological difference is there among males, and among females, and between males and females?

      A motivation behind this chapter is that genetic and anatomical differences are increasingly being detected between gay and straight people, between transgendered and nontransgendered people, and between and among intersexed and...

    • 13 Gender Identity
      (pp. 238-244)

      Do the brains of politicians and poets differ? Can we find a ricegrain of Beethoven’s brain shared by all composers and a different rice-grain of Picasso’s brain shared by all painters—anatomical markers of ability in performing and graphic arts? Perhaps. No one’s looked. But it is known that the part of the brain controlling left-hand fingers is larger in string players than in anyone else.¹

      As we have seen, among our vertebrate relatives, the two male genders of plainfin midshipmen fish have different brains, and in tree lizards, the three male genders develop with different hormone profiles. Ample biological...

    • 14 Sexual Orientation
      (pp. 245-261)

      If outside behavior matches inside morphology, then gay and lesbian people may have unique bodies. If string players have special brain parts for left-handed fingering, and race jockeys special genes for a short physique, then perhaps people of same-sex sexuality have special brain parts and/or genes for sexuality too. The search for biological aspects of sexual orientation often confuses sexuality with transgender expression.

      Remember the three rice-grains of nerve cells in the preoptic/hypothalamus area at the base of the brain? These grains, called SDN-POA, BSTc, and VIP-SCN, are sexually dimorphic in humans. VIP-SCN size seems to align with sexual orientation...

    • 15 Psychological Perspectives
      (pp. 262-279)

      My approach to variation in gender expression and sexuality is biological and behavioral, not psychological. Since Freud, however, gender and sexuality have often been discussed in psychological terms. I’m skeptical of psychology and, as a transgendered woman, have found psychologists to be dangerous, like gays and lesbians before me did. Psychologists operate with a medical model that pathologizes diversity. These medical wannabes have long persecuted and abused gender- and sexuality-variant people from a position of authority.¹ Nonetheless, some reviewers felt a purely biological account of gender and sexuality was incomplete and needed to be rounded out with psychological perspectives. Reviewers...

    • 16 Disease versus Diversity
      (pp. 280-305)

      A major threat to the human rainbow is the misclassification of human diversity as disease. Conventional techniques, from surgery to brainwashing, are applied to diverse peoples, often maiming them. Even those who escape overt injury live stigmatized lives, believing something is wrong with them. How could these abuses happen in today’s world?

      Medicine’s pathologizing of diversity springs from the absence of a scientific definition for disease. Medical dictionaries feature definitions like this: “Disease is an impairment of the normal state of the body that interrupts function, causes pain, and has identifiable characteristics.”¹ The problem with this definition lies in the...

    • 17 Genetic Engineering versus Diversity
      (pp. 306-326)

      Species need rainbows to survive, and today genetic engineering threatens our rainbow, as well as those of other species. Medicine threatens individuals, but genetic engineering threatens our entire species—our posterity. The damage from medicine is immediate, reflecting harm inflicted daily on people misclassified with fictional diseases, but harm from genetic engineering would reverberate through the future.

      The threat of genetic engineering springs from an arrogant belief that we should manipulate our gene pool. At times genetic engineering proposes to redecorate a whole rainbow, or it may target specific colors, such as those for unusual expressions of gender and sexuality....


    • 18 Two-Spirits, Mahu, and Hijras
      (pp. 329-351)

      By looking at how the universal human rainbows of gender and sexuality fit into the social categories of other societies around the world and at other moments in history, we may glean some ideas about how our own institutions might function better. Perhaps we can avoid the lost time and needless expense of suppressing biological difference. As with animal diversity, the facts of cultural diversity in gender and sexuality are unexpected and engaging. Yet, like natural science, the social sciences of anthropology, sociology, and history, as well as theology, all discount the very diversity that their painstaking research and primary...

    • 19 Transgender in Historical Europe and the Middle East
      (pp. 352-366)

      Gender variance was generally acknowledged by ancient writers in their descriptions of eunuchs, people similar to thehijra. We can find ancient eunuchs described in writings from the late Roman empire, from a.d. 100 to 400, as well as in the Bible and Islamic texts.

      As historian Mathew Kueffler recounts, the ancient Romans defined eunuchs as males who lacked functioning genitals.¹ The Roman lawyer Ulpian wrote, “The name of eunuch is a general one,” and he enumerated three types. Eunuchs “by nature” were those whose genitals didn’t continue developing at puberty. Such a person would have had sufficient genitals at...

    • 20 Sexual Relations in Antiquity
      (pp. 367-376)

      Same-sex sexuality was part of life in antiquity, although not as a category of personal identity. Whether one did or did not participate in same-sex sexuality no more defined who a person was, and who they thought themselves to be, than does, say, an appetite for French fries instead of potato chips. However, those who do eat French fries should avoid splashing ketchup on the table. Similarly, an appetite for same-sex sexuality required certain manners. The focus of social convention was not one’s choice of sexual partner, but rather how the sexual practice was carried out.

      Plato, the ancient Greek...

    • 21 Tomboi, Vestidas, and Guevedoche
      (pp. 377-386)

      This chapter leaves the Middle Ages and moves on to three examples of how human variations in sexuality, gender presentation, and bodies are being accommodated within contemporary societies.

      When I was about ten years old, I lived in the town of Bogor, in the hills of Java, Indonesia. I remember the wildlife, the flocks of fruit bats descending into the trees at sunset, the rain squalls, the steam rising from the road, the yummy rice cakes, the beautiful batik cloth, the red ants, the flowers—yes, the tropics at its best. I don’t remember anything at all about sexuality in...

    • 22 Trans Politics in the United States
      (pp. 387-400)

      Across-cultural survey of gender expression and sexuality would seem incomplete if the present-day United States were omitted. What’s happening here, where I write from, today? I believe what’s interesting here is that, all around us, new social categories are emerging to hold the people who formerly lived invisibly in the closet. This birth comes with pains and leaves stretch marks. The pain comes from the extraordinary threat of violence that transgendered people face just living their daily lives. The stretch marks come from the efforts to bend existing categories to encompass people whose reality is grudgingly being acknowledged.

      Trans people...

  9. APPENDIX: Policy Recommendations
    (pp. 401-408)
  10. Notes
    (pp. 409-460)
  11. Index
    (pp. 461-474)