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9 The Construction of Sexual Bimorphism and Heterosexuality in the Animal Kingdom Kirsten Smilla Ebeling Like transgendered humans, vaginaless female hyenas may seem strange. But life shows far more variety in the sexual realm, both within and among species, than our straight-and-narrow view of normalcy might suggest. (Margulis and Sagan 1997, 199) To most people in Western industrial cultures, the difference between male and female humans, animals, and plants is self-evident. In the same binary fashion, biologists categorize different forms of reproduction as sexual and asexual. In biology classes students may learn about hermaphrodites, like the earthworm, which have male and female reproductive organs. But despite the acknowledgment of animals that are both female and male, the sexes are considered dichotomous and heterosexual modes of reproduction are regarded as predominant. In this chapter, I describe animal species and forms of reproduction that do not ¤t into the bipolar classi¤cation system of sex and reproduction. Additionally , I question whether the primacy of sexual dimorphism and gonochorism1 can be maintained.I discuss this question in the context of interactions between human sex/gender relations and the production of biological knowledge.I point out that discursive processes involving negotiations about gender relations play an important role in biological theories about sex and reproduction.2 I use only examples from the animal kingdom, although an analysis of the binary system of sex and reproduction in the plant kingdom would be promising as well. For instance, as discussed in chapter 11 of this volume, the majority of plant species are not dioecious3 but hermaphroditic. Though I have encountered no comprehensive quantitative surveys of all plant species, Sabine Riewenherm ’s (1996) overview of more than 1400 European ®owering plants found that 92 percent were hermaphrodites and only 3 percent were dioecious.4 Others have examined biologists’ anthropomorphic heteronormative perspectives on plants (see chapter 11 of this volume; Schiebinger 1993). These are important avenues of research. Here, I limit my focus to the animal kingdom. I selected my examples mostly from popular biological texts that were published in German or in English (and sometimes in both languages) from the 1950s to the 1990s. While I have included texts from each decade of this period, my selection does not constitute a representative sample. Animal Species That Do Not Fit into the Dichotomous Sex Structure The study of hermaphroditism can be traced to the ancient world. Biologists describe simultaneous hermaphrodites, which are beings that have both female and male reproductive organs, and consecutive hermaphrodites, which have female and male reproductive organs serially. One consecutive hermaphrodite is the protogynous ¤sh species Bluehead wrasses (Thalassoma bifasciatum ), whose habitat is the Atlantic Ocean. Among this species all individuals are born female, but some change their sex as soon as their bodies reach a certain size. This sex change—as one biology textbook explains—is “socially controlled ” (Krebs and Davies 1984). If there are only a few large males and many females, some of the females turn into males. Other hermaphrodites undergo this process the other way around. For instance , all individuals of the protandric species Anemone¤sh (Amphiprion akallopisos ) are ¤rst male and may turn into females after reaching a certain body size. Again, this sex change is socially controlled: the Amphiprion akallopisos live as monogamous couples,and if the female of a couple disappears,the remaining male turns into a female and is joined by a new small male (Krebs and Davies 1984). Compared to these binary classi¤cations of simultaneous and consecutive protandric and protogynous hermaphrodites, the Thaliacea are more complex. These sea dwellers are small pelagic tunicates that have a stable but ®exible body covering called a tunic.5 Biologists describe a complicated alternation of generations among these animals: ¤rst, an egg develops into an individual that multiplies asexually by budding into four individuals; these, in turn, produce a colony through budding (Remane, Storch, and Welsch 1980). The hermaphrodites of such a colony are categorized into three types according to age. The oldest animals of a colony ¤rst produce sperm and later one egg. The middleaged individuals produce female and male gametes simultaneously, whereas the youngest animals of a colony ¤rst produce an egg and afterward sperm. Hence, this animal species includes four different types of simultaneous and sequential hermaphrodites, as well as protandric and protogynous hermaphrodites. In the class of the Turbellaria even more types of hermaphrodites are identi ¤ed. For example, biologists describe species in which the males and the females change their...

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