The Volokh Conspiracy

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What Is "Sex"?


My new trade book On Sex and Gender, out today from Simon & Schuster, developed out of an academic project—first in the legal literature with Sex in Sport (2017) and Sex Neutrality (2021), then with scientists and policymakers in the medical research and sports spaces. This interdisciplinary collaboration allowed me a forest-through-the-trees view of three separate storylines from science, law, and progressive advocacy, all with the same basic theme: What is 'Sex'? In this post, I excerpt sections of the book that summarize these separate storylines and conclude with a reflection on how, taken together, they inform the current moment.

Note: In my first post I explained that I use the word sex in its biological sense. In this post I use gender not as a synonym for sex but rather consistent with one or more of the three ways it's otherwise defined: (1) The expectations others attach to us because of our sex, i.e., gender norms. (2) The ways we express ourselves that are coded as gendered, i.e., gender expression. (3) Our inner sense of our sex and/or gender, i.e., gender identity.

From Science

The following excerpt is from Chapter Five, Sex Just Is (Like Age):

Before the late 20th century, there wasn't a great deal of interest in—and so no real funding for—research into how males and females are different beyond the fundamentals of sex development. Work on human anatomy, physiology, function, and disease continued, of course, but on the male model.

This almost singular focus and the corresponding erasure of the female model was rationalized on the historically ironic grounds that we're alike enough that it's okay only to use males as research subjects—and to assume that the typical human is the average male. The fact that the menstrual cycle makes it more difficult to study the female body—and that it is certainly more expensive to study both and then contrast the two—helped to lock in this focus even as it was obviously inconsistent with the premise of sameness to take this position.

As a result, researchers did such famously inane things over the years as to study breast cancer—which primarily affects females and is tied to estrogen and progesterone production—using only male research subjects.

The seeds of change were planted in the early 1990s when the NIH began requiring that both sexes participate in human research. But this initial effort fell short because the NIH didn't require researchers to compare males and females, or to analyze enough participants of each sex to be able to establish whether there were differences in the ways male and female patients with the same condition present, or the effects of sex on the safety and efficacy of a drug or treatment regimen.

It wasn't until 2014 that the NIH required that all animal research consider sex as a biological variable. This led to an explosion in work directly comparing the two sexes to establish whether significant differences exist.

A major milestone along the way between the two NIH decisions was the publication of the report Exploring the Biological Contributions to Human Health: Does Sex Matter? (2001)…. Its "overarching conclusion" was simple: "Sex matters."

Among its key findings and recommendations are that: "Every cell has a sex" and so research on sex at the cellular level should be promoted; sex begins in the womb, and so sex differences should be studied "from womb to tomb" when necessary by "min[ing] cross-species information"; and to "ensure the integrity of sex differences research, [the report] strongly recommended that researchers clarify their use of the two terms [sex and gender]."

As I was drafting these posts, a prominent group of sex differences researchers wrote in Nature that "dropping" this work "would impede progress in a long-neglected area of biomedicine." I am grateful to the lead author, Art Arnold of UCLA, for his assistance last year as I was working on this part of Chapter Five.

Nature's editorial board has since announced a series on the topic titled Why it's essential to study sex and gender, even as tensions rise, concluding that "Where disagreements persist, our hope is that Nature's collection of opinion articles will equip researchers with the tools needed to help them persuade others that going back to assuming that male individuals represent everyone is no longer an option."

From Law

The law, meanwhile, has been busy with the mostly convergent (to science) task that is separating what's real about sex from the gendered inferences and artifacts that societies attached to us because of our sex. Although this hasn't gone uncontested—see my next post—the underlying idea is that sex itself isn't inherently problematic, including as a legal classification; rather, the ways we treat people because of their sex may be.

Entirely apart from developments in science and medicine, this work has taken down a lot of the structural sexism that historically served to box us in but that's been especially damaging for females (whatever their gender identity) who have been marginalized (e.g., in medicine) and subordinated (e.g., in law and society) on the basis of assumptions and expectations people have about us because of our sex.

These three short clips from Chapter Two of the book are out of order, but together they take us quickly to the present moment with a nod to how we got here. I'll say more about the legal history in my next post and in Chapter Seven.

The law has come a long way in the century and a half since the Bradwell [(1873)] decision. Huge strides have been made to ensure that this institution is working only with real (not manufactured) and immutable (biological) differences. The best evidence of the success of this effort is probably the Bostock [(2020)] decision.

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Bostock affirmed that it was a violation of Title VII of the Civil Rights Act of 1964—which prohibits discrimination in employment on the basis of sex—for a funeral home to fire a transgender woman simply because she was transgender since doing this required taking into account her (male) sex, which was irrelevant to the job. In reaching this result, which guarantees that transgender people have the same rights in the workplace as everyone else, the Court declined to re-define sex away from biology to include gender identity.

[* * *]

[Bostock's] effect was to strip from the law's idea of male, not the biology because that's always been the through-line, but the blind inferences and harmful artifacts that suggested it's somehow unnatural to have a nonconforming inner sense of oneself and a correspondingly desire to live a concordant external life. In its place, the Supreme Court left a more minimalist definition of male and of sex that stands in stark contrast to the ornate versions of the past.

From Progressive Academia and Advocacy

At the same time, progressive academia and advocacy have been busy on the mostly divergent (to science and law) project that is (1) treating all sex differences—even real and valuable ones—as 'myths and stereotypes,' (2) either growing gender to include gender identity or erasing gender role and gender expression so that it's only gender identity, and (3) treating the new gender, whichever it is, as synonymous with sex.

This can be confusing and so I do my best to explain it in detailed steps, with examples, in Chapter Three. But for now, I hope it works to say that these moves depend on both the tradition of using gender as a synonym for sex and our willingness to see the male-female binary as a social construct built from just a small sub-set of our sex characteristics that we can reconstruct to suit new agendas. Here's a clip on this last point:

[I]f sex was ever real it's not anymore because most of our sex characteristics are now alterable using drugs and surgical procedures. By taking birth control pills year-round, I can avoid ever having a menstrual cycle and thus this multifaceted aspect of being female. A male child can take blockers at the onset of puberty and estrogen thereafter to avoid physical masculinization and thus this multifaceted aspect of being male.

There's also gender affirming "top" and "bottom" surgery—breast augmentation, removal of the penis and testicles, construction of a neovagina. People of either sex can micro-dose with cross-sex hormones and have facial reconstruction surgery to curate an androgynous form.

Given that all of this is now possible, the argument is that only our chromosomes and our gender identities are actually fixed or immutable…. Then comes the coup de grace: for policy purposes, including for purposes of defining sex, of the two remaining sex characteristics—chromosomes and gender identity—the latter is most important.

The Forest Through the Trees

Stepping out of our disciplinary silos allows us to see these three temporally overlapping storylines together, to consider the significance of each project to its keepers, and to gain an apolitical, nonreligious understanding of why this moment is so culturally, politically, and legally explosive. Leaving aside for a moment the deep significance of sex and gender to our fellow citizens who are religious conservatives, among other things, it helps to explain why a whole lot of us who aren't religious or conservative are at profound odds with progressive academia and advocacy even as we may otherwise self-describe, as I do, as liberal or progressive.

It explains, for example, why Judith Butler's recent call for warring feminists to set aside their differences and ally against the right using the advocacy groups' template won't work. As I write in the book, our resistance "is almost never because we don't care about trans people, it's because we also care about sex."