Sex categories
For organisms that reproduce via sexual reproduction, the biological convention is to label the individual donating the large gamete (egg), ‘female’, and the individual donating the small gamete (sperm), ‘male’.
In humans, who are complex organisms, reproduction (that is not medically-assisted) requires a set of organs: Gonads, which produce gametes (eggs are produced in the ovaries and sperm in the testis) and a set of genital organs.
In the vast majority of humans with ovaries, the genital organs take the form of fallopian tubes, womb, vagina, clitoris and minor and major labia – which are therefore termed ‘female genital organs’. In the vast majority of humans with testis, the genital organs take the form of vas deferens, seminal vesicles, prostate, penis, and scrotum – which are therefore termed ‘male genital organs’.
A small fraction of humans (less than 0.2%, Blackless et al., 2000; Hull, 2003) are born with genitalia that do not fit one of these two ‘sex categories’, either because of having one or more genital organs with a form intermediate between the female-typical and male-typical forms, or because of having some genital organs in the female-typical form and others in the male-typical form. These humans are typically referred to as intersex or with diversity of sex development (DSD).
Genetically, the vast majority of females have two X chromosomes, and the vast majority of males have an X and a Y chromosome. A small fraction of humans has a composition of the ‘sex chromosomes’ other than XX or XY (Blackless et al., 2000; Hull, 2003). Some of these other combinations have no effect on reproductive capacity (e.g., XYY) while others lead to sterility (e.g., XO).
The category of a person’s gonads (ovaries or testis) is determined already in utero. Currently, gonads can be surgically removed, but ovaries cannot be changed into testes or testes into ovaries.
Except in some DSD’s, the category of a person’s genital organs (female or male) is determined already in utero, and, unless medical intervention occurs, will not change throughout life. Currently available surgical and pharmacological interventions can alter or remove genital organs (e.g., a womb, a penis), for different purposes, including gender-affirming medical treatment.
We would like to note that while some individuals with gonadal, genetic, or genital variations may be unable to reproduce, many of the problems they face (such as unconsented genital surgery) are not a result of their biological condition but of the social importance of the sex categories in many societies (see below, under ‘gender’).
Sex-related hormones
Hormones are responsible for the differentiation of embryonic tissues into the different genital organs as well as later in life for the development and functioning of these organs as well as of secondary ‘sex characteristics’ (e.g., breasts, facial hair). We will refer to these hormones as ‘sex-related hormones’. The most known of these are testosterone, estrogen and progesterone.
In contrast to the genital organs, the sex-related hormones do not belong to two sets – female and male. Rather, they are found in all humans, in levels that overlap greatly (estrogen and progesterone) or moderately (testosterone) between female and male humans. Moreover, the levels of these hormones are very dynamic within each individual, changing in response to internal and external stimuli. For example, testosterone levels change in all humans following victory and defeat (reviewed in Hyde et al., 2019).
The level of sex-related hormones could be pharmacologically altered (e.g., by birth control pills, or medications for prostate or breast cancer), as well as for gender-affirming treatment.
The degree to which gender-affirming hormonal manipulations affect bodily characteristics is under debate. It is safe to say that it depends on time of administration (pre- or post-puberty) and varies from mimicking the typical bodily characteristics of the other sex (e.g., facial hair) to having no effect (e.g., height, if given post-puberty, e.g., Jordan-Young & Karkazis, 2019; Wiik et al., 2020).
Sex and the brain
Sex-related hormones also affect brain structure and function, in utero and throughout life. Yet, unlike genitalia and in contrast to a common myth, these effects do not add up consistently within individuals to create female and male brains. Rather, these effects interact with many other factors (Joel, 2011) to create unique mosaics of features, some in the form more common in females compared to males, and some in the form more common in males compared to females (Joel et al., 2015). Such mosaicism has also been found in several neural measures of the human hypothalamus, which show the largest known differences between females and males (Joel et al., 2020) (Read more about the Brain Mosaic here).
Gender
The term ‘gender’ has several meanings. It is used, unfortunately, as a synonym to sex; it refers to an individual’s inner feeling of being a girl/woman or a boy/man – a feeling termed ‘gender identity’; it refers to a set of psychological characteristics, masculine and feminine, that are considered appropriate to males and females or that are more common in males or females; it refers to a social system that attributes different meaning, status and power to whether one is female or male. It is this latter meaning to which ‘a world without gender’ refers.
Gender identity
The meaning of this term has changed considerably since it was used by John Money (1955) and Robert Stoller (1968) (reviewed in Mak, 2022). While Money used it to refer to one’s awareness of being male or female, as manifested in feminine or masculine behaviors (including sexual behavior), contemporary understanding treats gender identity as an inner, true, authentic self, often divorced from sex category (anatomy), gendered behaviors and traits (femininity-masculinity), and sexuality (Mak, 2022; Morgenroth & Ryan 2021; Tate et al. 2014).
Gender as a set of psychological characteristics
Although they may vary across cultures, most societies have different sets of behaviors and psychological characteristics which are deemed suitable for females (femininity) and males (masculinity). There are also group-level behavioral and psychological differences between human males and females, which often parallel the prescriptive gender stereotypes. However, at the individual level, sex/gender differences in behavioral and psychological characteristics rarely add up consistently within individuals to create to two types of humans. Rather, most humans possess unique mosaics of feminine (more common in women compared to men) and masculine (more common in men compared to women) characteristics (Joel et al., 2015, you can read more about gender differences in psychological and behavioral characteristics in Gender Beyond the Binary, coming soon.)
Gender as a social system
Gender is a social system that assigns different roles, status and power to males and females. Gender norms, stereotypes and social institutions affect most aspects of our lives, including our perception of ourselves and others, our social interactions across most (if not all) social contexts, and our access to power (read more about gender as a social system in Joel & Fine, 2022). A world without gender is a world in which this binary social system does not exist.
In modern Western societies, men, as a group, possess more of such valued resources as land and money, form a majority in legislative bodies and enjoy a higher social status than women. Understood as a structure of power relations, it is clear that the division of traits into feminine and masculine is not random. Qualities associated with males are characteristic of a dominant group (e.g., strength, aggressiveness, willpower). Qualities associated with females are those of a subordinate group (e.g., weakness, nurturing, gentleness) (Goffman, E. 1979. Gender Advertisements. London: The Macmillan Press Ltd, 46).
References
Blackless, M., Charuvastra, A., Derryck, A., Fausto-Sterling, A., Lauzanne, K. and Lee, E. (2000). How sexually dimorphic are we? Review and synthesis. Am J Hum Biol, 12(2), 151–66
Hull, C. L. (2003). How sexually dimorphic are we? Review and synthesis. American Journal of Human Biology, 15, 112–6
Hyde, J. S., Bigler, R. S., Joel, D., Tate, C. C. and van Anders, S. M. (2019). The future of sex and gender in psychology: Five challenges to the gender binary. American Psychologist, 74(2), 171–93
Jordan-Young, R. M. and Karkazis, K. A. (2019). Testosterone: An unauthorized biography. Boston, MA: Harvard University Press.
Joel D., Fine C. (2022) Who Is a Woman: Sex, Gender and Policy Making. Journal of Controversial Ideas, 2(2): 6. DOI: 10.35995/jci02020006
Joel D., Berman Z., Tavor I., Wexler N., Gaber O., Stein Y., Shefi N., Pool J., Urchs S., Margulies D., Liem F., Hänggi J., Jäncke L., Assaf Y. (2015) Sex beyond the genitalia: The human brain mosaic. Proc Natl Acad Sci U S A, 112, 15468–15473
Joel D., Garcia-Falgueras A., Swaab D. (2020) The complex relationships between sex and the brain. Neuroscientist, 26:156-169
Mak G. (2022) The Sex of the Self and Its Ambiguities, 1899–1964. D. McCallum (ed.), The Palgrave Handbook of the History of Human Sciences,
https://doi.org/10.1007/978-981
Morgenroth, T. and Ryan, M. K. (2021). The effects of gender trouble: An integrative theoretical framework of the perpetuation and disruption of the gender/sex binary. Perspectives on Psychological Science, 16(6), 1113-1142.
Tate, C. C., Youssef, C. P. and Bettergarcia, J. N. (2014). Integrating the study of transgender spectrum and cisgender experiences of self-categorization from a personality perspective. Review of General Psychology, 18(4), 302–12.
Wiik, A., Lundberg, T. R., Rullman, E., Andersson, D. P., Holmberg, M., Mandic, M., Brismar, T.B., Leinhard, O.D., Chanpen, S., Flanagan, J.N., et al. (2020). Muscle strength, size, and composition following 12 months of gender-affirming treatment in transgender individuals. The Journal of Clinical Endocrinology & Metabolism, 105(3), e805–13