There Are Still Only Two Human Sexes

It baffles me that, in furtherance of Woke ideology, so many people are somehow willing to pretend that human animals come in more than two sexes. These pretensions are part of an “antiscientific trend toward the outright denial of biological sex.” These arguments often take one of two forms: the argument from intersex conditions and the argument from secondary sex organs/characteristics. At Quillette, Colin Wright, who holds a PH.D. in evolutionary biology, explains that both of these arguments fail. His article is titled “JK Rowling Is Right—Sex Is Real and It Is Not a “Spectrum”:

[Both arguments involve] fundamental misunderstandings about the nature of biological sex, which is connected to the distinct type of gametes (sex cells) that an organism produces. As a broad concept, males are the sex that produce small gametes (sperm) and females produce large gametes (ova). There are no intermediate gametes, which is why there is no spectrum of sex. Biological sex in humans is a binary system.

It is crucial to note, however, that the sex of individuals within a species isn’t based on whether an individual can actually produce certain gametes at any given moment. Pre-pubertal males don’t produce sperm, and some infertile adults of both sexes never produce gametes due to various infertility issues. Yet it would be incorrect to say that these individuals do not have a discernible sex, as an individual’s biological sex corresponds to one of two distinct types of evolved reproductive anatomy (i.e. ovaries or testes) that develop for the production of sperm or ova, regardless of their past, present, or future functionality. In humans, and transgender and so-called “non-binary” people are no exception, this reproductive anatomy is unambiguously male or female over 99.98 percent of the time.

The binary distinction between ovaries and testes as the criterion determining an individual’s sex is not arbitrary, nor unique to humans. The evolutionary function of ovaries and testes is to produce either eggs or sperm, respectively, which must be combined for sexual reproduction to take place. If that didn’t happen, there would be no humans. While this knowledge may have been cutting edge science in the 1660s, it’s odd that we should suddenly treat it as controversial in 2020.

More recently, in an article titled “Sex Chromosome Variants Are Not Their Own Unique Sexes,” Wright responded to a Tweet by a purported biologist named McClean, making an unusual claim.

McLean, who prominently lists five degrees after his name and claims to be a human evolutionary geneticist, took issue with that claim and forwarded a very common—and very wrong—portrayal of biological sex: that different sex chromosome compositions beyond the standard XX and XY each represent their own unique sex. In fact, Dr. McLean appears to suggest in his tweet that there may be as many as 10 biological sexes!

It especially concerned Wright that McClean’s groundless claim was retweeted more than 4,000 times. There is apparently a hot market for bad biology.

First, Wright restates McClean’s claim:

The argument that individuals with sex chromosomes that deviate from the typical (46, XX and 46, XY) arrangements, such as those with Klinefelter syndrome (47, XXY) or Turner syndrome (45, X0), is common and usually used to argue that there are 6 sexes, though other numbers are frequently thrown around as well.

The proper response to the above claim is, again, that the size of the gametes determine sex. Males produce small gametes (sperm) and females produce large gametes (ova). Since some individuals do not actually produce gametes, we sometimes need to look to the sex organ rather than the gamete.  Once we do that, we can still see that there are only two sexes.  Wright explains:

But on an individual level (since not all individuals may be able to produce gametes) an organism’s sex corresponds to the type of primary sex organs (testes vs ovaries) and individual has developed. In mammals, which includes humans, the Y chromosome carries a gene (SRY) that encodes a testes-determining factor. If an individual has a Y chromosome with a functional SRY gene, they will develop testes and therefore will be biologically male. Absent a Y chromosome and functional SRY gene (unless the SRY gene has been transposed to an X chromosome), an embryo will develop ovaries and will therefore be biologically female. What’s important to note is that the presence of a Y chromosome, or two, or three, etc., all result in the development of testes and therefore these individuals are biologically male. Likewise, individuals with additional or fewer X chromosomes, in the absence of a Y, all develop ovaries and are therefore biologically female. With this in mind, the chart in the above tweet can more accurately be rewritten as:

X – Female
XX – Female
XXY – Male
XY – Male
XYY – Male
XXXY – Male

Wright concludes that these atypical chromosomal patterns do not result in new sexes, “but rather represent natural variation within males and females.”

Ergo, there are still only two sexes.  It’s interesting to note that there does not seem to be any confusion about this when discussing any animal other than humans. In this way, the Woke position on “many sexes” reminds me of claims by religious fundamentalists that evolution by natural selection is straightforward until those upstart biologists start trying to apply natural selection to human animals.

I might be wrong, of course.  Therefore, I’ll keep an eye out for ferocious arguments from Woke biologists that squirrels, hamsters and flowers come in six sexes (and unlimited numbers of genders).

[Supp 2025.10.31]

Saturday Night Live transgender skit from 1987 (and the audience reaction) illustrates how things have changed.

“How incredible to see that a comedy skit broadcast in 1987 on Saturday Night Live would set the stage for a real life mass medical scandal that became viral in 2020.”

Screenshot 2025 10 31 at 1.13.30 PM

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Erich Vieth

Erich Vieth is an attorney focusing on civil rights (including First Amendment), consumer law litigation and appellate practice. At this website often writes about censorship, corporate news media corruption and cognitive science. He is also a working musician, artist and a writer, having founded Dangerous Intersection in 2006. Erich lives in St. Louis, Missouri with his two daughters.

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  3. Avatar of johnE
    johnE October 13, 2021 Reply

    For anyone interested in this subject Abigail Shrier’s book “Irreversible Damage” might be of interest. It goes into the biology, psychology and culture of sex-change therapy.

  4. Avatar of Erich Vieth
    Erich Vieth October 20, 2025 Reply

    “There Are Only Two Gametes: The gametic understanding of sex is consensus mainstream science that makes research and understanding possible across a variety of key fields. So why are professors at Harvard and Princeton and editors at ‘The Lancet’ framing it as bigotry?” by Carole Hooven. Excerpt:

    It might be helpful to think about the act of sex, perhaps in nonhuman species like chickadees or chacma Baboons. In sexually reproducing organisms (the overwhelming majority of animal species), while sex often satisfies a deep drive and is generally enjoyable, enjoyment is not the primary purpose of sex; it is instead a strong motivator, natural selection’s solution to get animals to engage in an often-risky behavior that requires a significant expenditure of energy. The primary purpose of sex is to produce offspring that combine the genetic material of their parents, so that those offspring can go on to pass on their DNA to future generations, and so on.

    Moreover, sexual reproduction in animals can only occur when two distinct types of gametes (specialized sex cells containing DNA) fuse: the small mobile ones (sperm) and the large immobile ones (eggs). We call animals that produce sperm “male” and those that produce eggs “female.” That’s about it. The bottom line is that there are two gamete types and thus two sexes. There are no other sexes, no other reproductive categories.

    Among mainstream evolutionary biologists, there is simply no disagreement on these basic points: The “gametic view” is the established orthodoxy of our field. It applies across sexually reproducing animals and accommodates all the complexity and variation within the sexes. It holds in nonreproductively viable animals—like postmenopausal me—that don’t produce gametes; it holds in male seahorses that get pregnant; in clownfish who change from male to female (first producing sperm and then eggs); in females who identify as male (trans men) and take male levels of testosterone and have a deep voice and a thick, bushy beard.

    There are no additional or intermediate gametes. There are only sperm and eggs. Therefore, there are only two sexes, even if some people (or other animals) don’t fit obviously or neatly into one sex or the other. Traits associated with sex—like chromosomes, hormones, brain, feelings, or behavior—are not binary; nor do they define sex. However, there are two, and only two, sexes.

    I think Hooven is completely right. If one thinks of sex in terms of non-human species, it all so very clear. People go off the rails when they deal with human animals. They invent things like souls, immortality and more than 3 sexes.

    More on Carole Hooven, from Grok:

    Overview. Carole K. Hooven is an American evolutionary biologist, author, and educator known for her research on hormones, sex differences, and human behavior. She gained prominence for her book on testosterone and became a vocal advocate for academic freedom after facing backlash at Harvard University over statements on biological sex. Hooven emphasizes evidence-based science in discussions of gender, evolution, and campus culture, often challenging prevailing ideological norms in academia.

    . . . .

    Hooven spent over 20 years at Harvard, initially as a lecturer and co-director of undergraduate studies in the Department of Human Evolutionary Biology. She was an award-winning teacher, praised by students for her engaging style and clarity in explaining complex topics like evolutionary biology. In 2023, she transitioned to an associate role in Harvard’s Department of Psychology, working in the lab of cognitive psychologist Steven Pinker, where she continues research on sex differences and hormones.Currently, Hooven is a nonresident senior fellow at the American Enterprise Institute (AEI), a conservative think tank, where she contributes to discussions on science, education, and free speech. She is working on a new book exploring related themes in evolutionary biology and culture.

    …

    Controversies and Advocacy for Academic FreedomIn July 2021, Hooven sparked controversy during a Fox News interview, stating that biological sex is binary—”designated by the kinds of gametes we produce” (sperm or eggs)—while affirming respect for gender identities. This drew sharp criticism from Harvard students, faculty, and a graduate student teaching assistant, who accused her of harming trans and nonbinary people. The backlash included public shaming, ostracism by colleagues, and a department-wide email from the head of Human Evolutionary Biology distancing itself from her views, leaving her feeling unsupported.Hooven described the incident as a “DEI web” that prioritized ideology over science, leading to her resignation from her Harvard lecturing role in late 2023. She detailed this in a January 2024 Free Press essay, “Why I Left Harvard,” citing a toxic environment where “feelings overrode rational debate” and grade inflation eroded standards. The episode catalyzed the formation of Harvard’s Council on Academic Freedom in 2023, aimed at protecting intellectual diversity, with her case as a key example.In February 2024, the Foundation for Individual Rights and Expression (FIRE) awarded Harvard its “lifetime censorship award” for suppressing speech, explicitly referencing Hooven’s treatment. She has since become a prominent critic of “cancel culture” in academia, appearing on podcasts like Andrew Sullivan’s The Dish to discuss Harvard’s “existential crisis” and the erosion of viewpoint diversity. Hooven argues that monocultures in higher education—often progressive and female-dominated—stifle debate, as explored in her endorsements of works like Cory Clark’s research on women’s stronger inclinations toward moralistic punishment of dissenting scholars.Recent ActivitiesAs of October 2025, Hooven remains active in public discourse.

    On X (formerly Twitter, @hoovlet , with over 45,000 followers), she engages with topics like sex differences in infidelity judgments, critiques of puberty blockers (clarifying her book’s 2019 context on their partial reversibility), and autism spectrum discussions. She co-hosted an AEI event in July 2025, “Do Women Owe Men an Apology?”, examining gender dynamics in education and culture. Hooven continues advocating for “decolonizing” syllabi through evidence, not ideology, and warns against equating high-functioning individuals with severe autism cases.Her story underscores tensions between biological science and social justice in elite institutions, positioning her as a bridge between evolutionary research and free-speech advocacy.

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