their sexual orientations and behaviors. In her review of biological theories about sex and gender, Sayers defined biological essentialism as the view that “biology has endowed women with an essential femininity” (1982, p. 147). Maracek offers the following definition of essentialism as it relates to sex and gender, saying:
This view of gender holds that the categories “man” and “woman” are natural, self‐evident and unequivocal. It regards sex‐linked behaviours and traits as fixed and stable properties of separate and autonomous individuals. (1995, p. 162)
Essentialism is a broader concept than biological determinism. It refers to theories or viewpoints that account for differences between categories by ascribing to them enduring, fixed, and prototypical characteristics. In other words: their essence. Haslam and Whelan. define essentialism as “The claim that there are natural kinds whose members share a common essence” (2008, p. 1297). As a theoretical perspective, essentialist thinking is often found when the focus is on identifying differences between the sexes or specifying the nature of womankind. One of the main justifications for essentialist views of sex differences is a commitment to biological determinism but essentialist theories can be based on differences that are seen to have sociocultural origins, usually taking effect in infancy or early childhood.
Defining Sex, Gender, and Sexuality
In discussing theories of causation in relation to sex and gender it is important to note the use of terminology since the terms, sex and gender, are often used interchangeably, especially in daily discourse and in the popular media. For example it is common on official forms to be asked to specify one's gender when it might be more precise to ask about one's sex, which is probably the information that is being sought. The American Psychological Association (APA) defines sex and gender as follows, “Sex usually refers to the biological aspects of maleness or femaleness, whereas gender implies the psychological, behavioral, social and cultural aspects of being male or female, (i.e. masculinity or femininity).” (http://www.apa.org/pi/lgbt/resources/sexuality‐definitions.pdf).
However, having said that, these distinctions can readily break down, and not only in popular usage. The designation of sex is made on the basis of the presence of a complex of structures and processes, including the sex chromosomes, gonads, hormones, external genitalia, and secondary sexual characteristics, and all of these elements can be present in different degrees at birth causing ambiguity about the assignation of sex, or they can be altered by later accidental or deliberate interventions. Thus, even at a biological level, sex is a complex cluster of characteristics, not one simple characteristic. Butler adds to this picture the view of sex as permeated with social meanings such that the distinction between sex as biological and gender as social breaks down (1990). This problem in distinguishing sex and gender has been taken on board by some contemporary theorists. For example, in a more recent paper on “Neurofeminism and feminist neurosciences” Schmitz and Höppner have decided to use the term “sex/gender” (2014). Increasingly then, there is recognition of the difficulties that arise in adopting the traditional definition of sex, which implies that sex is always dimorphic, that there are only two sexes, male and female, and that they do not change over the life course. The use of the terms sex and gender thus remains problematic.
The definition of sexuality or sexual orientation is also a matter for debate. Sexual identity and sexual desires, and behaviors are complex and can also be unstable across the life course. The APA offers a definition of sexual orientation stating that it is, “A component of identity that includes a person's sexual and emotional attraction to another person and the behavior and/or social affiliation that may result from this attraction” (http://www.apa.org/pi/lgbt/resources/sexuality‐definitions.pdf). This definition can be seen as essentialist and certainly the term “sexual orientation” is often used as though an individual's sexuality is fixed and unchanging. Social constructionists will often use the term “sexual preference” indicating a degree of choice and openness (Rosenblum and Travis 2016).
Biologically deterministic theories about sex, gender, and sexual orientation typically see all three as intrinsically linked and mapping neatly onto each other, with common biological origins. Thus, from this perspective, being female implies being feminine and attracted to males. This assumption forms the basis of what Adrienne Rich terms “compulsory heterosexuality,” the view that heterosexuality and attraction to the opposite sex is natural to the female sex and that any deviation from this is therefore unnatural and open to a wide range of hostile responses on the part of heteronormative societies (1980). Transgender people who reject the sex to which they were assigned at birth are an example of the uncoupling of biological sex and gender identity (Chrisler and McCreary 2010). Although it is the case that for centuries, sex, gender, and sexuality have been seen as different facets of the unified biological essence of men and women, increasingly these three elements are seen as separable and as potentially fluid (Diamond 2009), as discussed in a later section of this chapter.
Biological Theories about Sex and Gender
For some decades the majority of natural and social scientists have come to view extreme biological determinism as an untenable position because of the incontrovertible evidence that human behavior is strongly influenced by social and cultural factors. Thus very few of them would identify as hardline biological determinists and what becomes a matter of dispute is the extent to which scientists emphasize the social or the biological. However recent developments in neuroscience, evolutionary psychology and the “new genetics” have bolstered biologically based explanations of male–female differences (e.g. Buss 1995; Baron‐Cohen 2004; Brizendine 2007), provoking a second wave of feminist critiques of what they see as sexist and deterministic theories and assertions.
As discussed earlier, the aspect of biology seen as central to male–female difference or women's character has shifted over the centuries. Scientists no longer hold that important consequences arise because female bodies are moist whereas those of males are dry, as Galen asserted, or that female moodiness is because the womb has come adrift and is causing havoc, as Plato suggested. There is a number of theories that are actively discussed in recent and current literature and they focus on genes and evolution, hormones, and brains. The links between genes, evolution, hormones, and brains are strong. For example, biological differences between the sexes in brain function are seen by writers such as Herbert (2015) as due to sex‐linked hormones activated in utero and in the first months of life that shape the brain of males and females in different ways. In the following sections some recent theories will be elaborated, along with critical reactions to them.
Evolution and Genes
Sociobiological explanations of sex differences were particularly popular in the 1970s and 1980s with the publication of books like “Sociobiology: The New Synthesis” by Wilson in 1975 and “The Selfish Gene” by Dawkins in 1976. Wilson defined sociobiology as “the systematic study of the biological basis of all social behavior” (1975, p. 4) and argues that human nature is largely dictated by a set of evolved traits. He and other sociobiologists such as Barash (1977) see sexual difference as rooted in our early evolution, at a time, they argue, when the fundamental structure and function of our brains were set down. Given the demands of the primitive life, brains of males and females diverged to suit males to hunting and competitive behavior and women to child‐rearing and nurturing behavior. Such behavioral dimorphism was adaptively advantageous and secured the survival and reproductive success of the species. Barash recommends acquiescing to our biological natures, saying, “there should be a sweetness in life when it accords with the adaptive wisdom of evolution” (1977, p. 25).To sociobiologists, much of both male and female behavior is seen to be explicable in terms of reproductive strategies designed to optimize both sexes' chances of having many healthy offspring, and perpetuating their genes. A small number of theorists claimed to be feminist and advocates of biological
