Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
Here’s a new article in Nature (click on the title screenshot below to read it); it’s about the dearth of information about the safety of drugs used by pregnant women. Except, to Nature, they refer not to “women” but to “pregnant people,” for in the article, that is about the only term that refers to women who are pregnant. “Women” is used almost exclusively when it’s in quotations from others.
Here’s my count:
“Pregnant people”: Used 41 times
“Women”: Used 5 times, 4 of them in quotes from others
Clearly some bowdlerization is going on here.
The sad part of this article is that it has a lesson worth reading—a dearth of knowledge about how many drugs affect pregnant women—but it’s annoyingly peppered with politically correct and annoying usages. For example:
The first usage of the “pp” term is in fact in the subtitle, which I’ve highlighted below (again, click the article to read it):
Here’s a screenshot with “pregnant people” highlighted. This is only a small sample of the article:
Need I say more? What this means is that Nature is clearly truckling to the language adopted by extreme gender activists, who consider trans-identified men as “women”. Ergo, the words “pregnant women” are seen as offensive, because “women” include trans-idenfied men who can’t have babies. Voilà: “pregnant people.” Also, as reader Coel says below, “The main problem is trans-IDing women, aka ‘trans men’, who, being women, can get pregnant, but who they regard as ‘men’. Hence ‘pregnant women’ would exclude them, and so amount to erasure of and thus genocide of those ‘trans men’ who are indeed pregnant.”
Here are the five uses of the word “women”, all but the last quotes from other authors (they can’t sanitize other people’s words):
Note that the last usage of woman, not in quotes, is required because they are referring to females who are not pregnant. But the journal still slipped up: they could have used “people with uteruses”, or, like TheLancet, “bodies with vaginas”:
Conclusion: Nature has been ideologically captured. But we already knew that, didn’t we?
Although the view that sex is a spectrum, and that there are more than two biological sexes in humans and other species, is still prevalent among the woke, others are realizing that sex in humans (and nearly every other species of plant and animal) is indeed a binary, with a tiny fraction of exceptions in humans. These include individuals with “differences in sex determination” (DSD) and almost nonexistent hermaphrodites. Estimates of exceptions in our species range from 0.02% to 0.005%.
The rise of the “sex is a spectrum” notion is due solely to the rise of gender activism and to people who identify as nonbinary or transgender. But gender is not the same thing as biological sex: the former is a subjective way of feeling, while the latter is an objective fact of biology based on a binary of gamete types.
I personally don’t care if someone identifies as a member of a nonstandard gender, but I do care when people like Steve Novella, who should know better, argue that biological sex is not a binary but a spectrum. In fact, there are far more people born with more or fewer than 20 fingers and toes than are born as true intersexes, yet we do not say that “digit number in humans is a spectrum.”
It’s a shame that many of those who claim that sex is a spectrum are biologists who recognize the sex binary and its many consequences, like sexual selection. The misguided folks include the three main scientific societies studying evolution, who issued a statement that biological sex was a spectrum, and further that this was a consensus view. (Their original statement is archived here.) The societies then took down their claim when other biologists pointed out its inanity (see here, here, and here). And it’s not only biologists who recognize the ideology behind the claim that sex is a spectrum; the public does, too. NBC News reported this in 2023 (note the conflation of sex and gender):
A new national poll from PRRI finds Americans’ views on gender identity, pronoun use and teaching about same-sex relationships in school deeply divided by party affiliation, age and religion.
Overall, 65% of all Americans believe there are only two gender identities, while 34% disagree and say there are many gender identities.
But inside those numbers are sharp differences. Fully 90% of Republicans say there are just two genders, versus 66% of independents and 44% of Democrats who believe the same
Sadly, if you’re on the side of truth in this debate, at least as far as the number of sexes go, you’re on the side of Republicans. So it goes. Further, Americans and sports organizations themselves are increasingly adopting the views that trans-identified men (“transwomen,” as they’re sometimes called) should not compete in sports against biological women. This is from a 2025 Gallup poll.
Sixty-nine percent of U.S. adults continue to believe that transgender athletes should only be allowed to play on sports teams that match their birth sex, and 66% of Americans say a person’s birth sex rather than gender identity should be listed on government documents such as passports or driver’s licenses.
Thus, although wokeness is like a barbed porcupine quill: easy to go inside you but hard to remove, I’m pretty confident that the claim of a biological sex spectrum will eventually decline even more. But there are still some ideologues who twist and misrepresent the facts to argue that there are more than two sexes. (The argument centers on humans, of course.) One of these is Princeton anthropologist Agustín Fuentes, who has written several papers and a recent book arguing for the human sex spectrum. I’ve pushed back on his arguments many times (see here), and wrote a short review of his book Sex is a Spectrum, a book that should be read with a beaker of Pepto-Bismol by your side. There’s another and better critical review of Fuentes’s book by Tomas Bogardus, here, which Bogardus has turned into his own new book, The Nature of the Sexes: Why Biology Matters.
This post is just to highlight another critical review of Fuentes’s book and his views on sex, one written by Alexander Riley and appearing at Compact. You can get to a paywalled version by clicking on the title below, but a reader sent me a transcript, and I’ll quote briefly from that below.
A few quotes (indented). I don’t know how readers can access the whole review without subscribing:
Fuentes, an anthropologist who has extensively studied macaques, begins with a primer on the evolution of sexual reproduction in life on the planet. To show how “interesting” sex is, he offers the example of the bluehead wrasse, a fish species in which females can turn into males in given ecologies. The example, he says, is “not that weird” in biology.
But the reality is that species like this one most definitely are weird, not only in the animal kingdom, but even among fish, who are among the most sexually fluid animals. Among fish, the number of species that are sexually fluid in this way is perhaps around 500 … unless you know that there are approximately 34,000 known fish species. In other words, even in the most sexually fluid animals, transition between male and female by one individual can happen in only 1.5 percent of the total species. What Fuentes describes as “not that weird” is certainly highly unusual. [JAC: note that switching from male to female or vice versa does not negate the sex binary.]
This sleight of hand is typical of Fuentes’s handling of evidence. He attacks a classic argument in evolutionary biology that differences in male and female gametes (sperm an eggs, respectively) explain many other differences between the two sexes. In short, because eggs are much costlier to make than sperm, females have evolved to invest more energy in the reproductive chances of each gamete compared to males. This bare fact of the gamete difference means, according to the Bateman-Trivers principle, males and females typically develop different mating strategies and have different physical and behavioral profiles.
The distortion below is typical of ideologues who promote Fausto-Sterling’s data even when they know it’s incorrect:
Fuentes notes that what he calls “3G human males and females,” that is, those individuals who are unambiguously male or female in their genitalia, their gonads (the gland/organ that produces either male or female gametes), and genes, do not make up 100 percent of human individuals. He goes on to suggest that at least 1 percent of humans, and perhaps more, do not fit the 3G categories. This is a claim unsupported by the facts. The citation he links to this claim is an article by biology and gender studies professor Anne Fausto-Sterling. The claim made by Fausto-Sterling about the percentage of those who are intersex has been thoroughlydebunked. She includes a number of conditions in her category of intersex (or non-3G) that are widely recognized as not legitimately so classified. One such condition (Late Onset Congenital Adrenal Hyperplasia, or LOCAH, a hormonal disorder) makes up fully 90 percent of Fausto-Sterling’s “intersex” category. Individuals with LOCAH are easily classed as either male or female according to Fuentes’ 3Gs, and nearly all of them are able to participate in reproduction as normal for their sex. The percentage of those who are actually outside 3G male or female classes is likely around 0.02% percent, which means that 9,998 out of every 10,000 humans are in those two groups.
What’s below shows that trans-identified men do not become equivalent to biological women when they undergo medical transition:
Transwomen are much more likely to exhibit behaviors of sexual violence and aggression than women. A 2011 study showed clearly that even male-to-female transsexuals who had undergone full surgical transition, and who therefore had undergone hormone therapy to try to approximate female hormonal biology, still showed rates of violent crime and sexual aggression comparable to biological males. They were almost twenty times more likely to be convicted of a violent offense than the typical female subject. This is reason enough to keep individuals who have male hormonal biology out of spaces in which they interact closely with semi-clad girls and women.
And Riley’s conclusion:
The fact that Fuentes can make such ill-founded claims without fearing serious pushback is an indication of how captured academic culture is by the ideology behind this book. A healthy academic culture would not so easily acquiesce to political rhetoric masquerading as science.
Yes, anthropology has been captured—especially cultural anthropology—and, as I said, even some biologists have gone to the Dark Side. I have nothing but contempt and pity for those who know that there are two sexes but twist and mangle the facts to conform to the woke contention that the sexes can be made interchangeable. But I should add the usual caveat that, except for a few exceptions like sports and prisons, transgender people whould be given the same rights as everyone else.
Another sign of people rejecting the “sex is a spectrum” claim is that Fuentes’s book didn’t sell well. Despite coming out less than a year ago. it’s now #301,447 on Amazon’s sales list, and has only 25 customer ratings, totaling 3.8 out of 5 stars. It didn’t exactly fly off the shelves.
Here are two Amazon reviews by savvy readers (note: none of the reviews on Amazon are by me):
Yesterday we were talking about Michael Shermer’s new book on Truth, but only insofar as I disagreed with his podcast characterization of free will. Now, however, while promoting his book on the radio, Shermer encountered some misleading “progressivism” about sex from one of public radio’s most well-known announcers and on NPR’s biggest station: Brian Leher on WNYC in New York. You can read about what happened by clicking on the sceenshot below at BROADview News. And below that you can hear the whole 35-minute interview of Shermer by Lehrer by clicking on the black screenshot and then on the “listen” arrow. You might want to start about halfway in (see below).
First, some excerpts from the article:
Like so many liberals, I grew up with NPR as my soundtrack: BJ Leiderman’s thumping theme songs in the background, or the soothing voice of the late great Susan Stamberg. I loved NPR.
It became difficult to listen to starting in 2016, as the mission changed from reporting to making sure that we all had the same opinion. Then, once Katie Herzog mentioned a game in which you turn NPR on at random times and see if they’re talking about race, NPR started to seem like a joke. But also: it wasn’t funny. It wasn’t funny when they reported on gender—because they often reported activist talking points about the medical interventions as facts, and labeled truths as disinformation.
We’ve seen shifts in other mainstream media outlets, even a kind of two-steps-forward, one-step-back movement in The New York Times’ reporting on gender. But NPR is more dug in than ever. I assume this is in reaction to the defunding of the Corporation for Public Broadcasting. To admit that they were so biased that they didn’t deserve public funding was to retire their pitch for more funding from listeners—although what they should have done was pivot, to do a better job and argue that they deserved the funding.
All this is background for what happened yesterday on WNYC, the most-listened-to public radio station in the country. Journalist Brian Lehrer has hosted a weekday news call-in show for some 35 years, and was widely admired as one of the best out there—fair-minded and willing to engage with different voices. Like many others in the media, he changed.
You can see the change when “Mabel” calls in at 16:23. Mabel apparently didn’t tell the call screener what she wanted to say on the air, because she actually got through to the broadcast. Mabel then emphasized that there were two biological sexes and members of one cannot become members of the other. As you’ll hear, Lehrer pushed back, saying that biological sex can be changed through “transgender’ hormones and surgery. (Lehrer apoparently doesn’t know the difference between sex and gender.) More from the article:
Mabel likely didn’t tell the screener what she really wanted to say, because it started with how America is becoming a third-world country and complaints about the lack of affordable housing. But then she said “The Democratic Party has let me down,” because they’ve also been untruthful. “Now they’re saying that men can become women and I feel that you are just discounting women as a species,” she said. Dems were “trying to make us believe that you can turn a male into a female.” She added that women were more than their anatomy; they were also shaped by their experiences.
That last part allowed Lehrer to make his case that “trans women would say they had their experience of being a woman before they had any hormone replacement therapy or surgery.” Amazingly, he added: “Maybe you’re just biased against a segment of society who you don’t like.”
Actually, you don’t have the experience of being a woman before you transition; you have the feeling that you are a woman and want to change aspects of your body to conform to that. More:
This was absolutely shocking—to hear Brian Lehrer, the former Voice of Reason, tell a caller that because she feels lied to about this issue she’s hateful was astonishing, and just incredibly unprofessional.
Shermer, on the other hand, handled it like a champ. He went into the difference between subjective truths—I feel like I was born in the wrong body—and objective ones: we cannot change sex, which is binary and based on gametes. Shermer said he worried about the future of the Democratic Party because it cannot distinguish between objective and subjective truths.
Lehrer himself seemed to be in shock, having hermetically sealed his studio to protect against any facts that interrupted the narrative he’d constructed. “This is what the right wing says, that it’s gender ideology,” he retorted. WNYC has worked hard to exclude liberal dissident voices, which has allowed them to maintain that left/right framing.
But Shermer pushed on. He explained the difference between the vanishingly rare occurrence of childhood-onset gender dysphoria and rapid-onset, the theory of social contagion, the poor evidence base, the shift in several European countries. “The facts matter,” he said.
Lehrer: “It sounds like you’re being very dismissive.” He said doctors would disagree that you can’t change sex, or that sex is binary. And finally, when Shermer came back with reasonable answers, Lehrer said: “You’re here supposedly representing science.” That is: Lehrer believed Shermer had lost all credibility by applying the same lens to youth gender medicine that he applied to everything else.
Most shocking about this whole exchange was what happened after it ended. Lehrer invited people who were offended to call in. After Shermer was gone! “Equal time,” he said—as if they’d ever given a minute to any of us wanting to share another side of the story.
And so, the parents and grandparents and uncles of trans kids rang up. . . .
Shermer did handle it like a champ, acknowledging that biology is binary but gender is an “internal, subjective state.” If you want to just hear the relevant exchange, start the podcast at 16:23.
At the end of the piece, author Lisa Davis gives the emails of the segment’s producers in case readers or listeners want to write them, but you can go to the site above and complain if you wish. Regardless, Lehrer shows how fully NPR has bought into the theory that humans can change from one sex into another. Shermer does a great job correcting Lehrer, emphasizing that gender is an internal, subjective state and, as far as biological sex goes, we are not clownfish: humans can’t change from one sex to another.
Here we have a five-minute video that, I think, goes some way towards understanding why the Democrats lost the last Presidential election and have dropped in public approval to the lowest point in several decades. The graph below, which appears in The Liberal Patriot’s post “Why is Democratic Favorability at a 25-year Low?“, shows that both parties have fallen in ratings since 2000,, but as of mid-2025 Democrats have done worse than Republicans. (Note that the latest data might not correspond to this.) But there’s enough unfavorability of “our” party that Democratic strategist David Plouffe argues in today’s NYT that “To win everywhere, Democrats must change everything” (op-ed archived here).
UPDATE: Some more recent data:
After all this, Americans still hate Democrats more than they hate Republicans.
Now I’m no political pundit, but I’m not the only person to suggest that the wokeness of the Democratic party as espoused by its more vocal “progressive” wing is hurting the party as a whole. The implicit call for open borders, the explicit claim that biological sex is simply the way one identifies rather than a physical reality (a stand that conflates gender and reality), and the Kendi-an viewpoint criticized in John McWhorter’s book Woke Racism—all of this seems to me to turn off centrist voters or the more sensible Republicans who aren’t firm MAGA-its.
The video below, which I found on YouTube after someone sent me a clip, instantiates the kind of view that alienates reasonable people. Here we have Dr. Nisha Verma refusing to admit that men cannot get pregnant. She is clearly conflating gender (sex-identification) with biological sex, which involves the ability to produce either large, immobile gametes (females) or small mobile ones (males). Only biological women can get pregnant, for they have the reproductive apparatus evolved to produce eggs and carry fetuses. (Note that removing that apparatus, as during a hysterectomy, does not suddenly change a female into a male).
This is part of a Senate hearing on the safety of abortion medication. AcademyHealth gives Dr. Verma’s credentials this way:
Dr. Nisha Verma is a board-certified obstetrician-gynecologist and complex family planning subspecialist. She currently serves as Senior Advisor for Reproductive Health Policy & Advocacy at ACOG. She is Adjunct Assistant Professor at Emory University School of Medicine and provides clinical care in Georgia and Maryland. She has testified in front of Congress on the harms of abortion restrictions and currently has a research grant to explore the impact of Georgia’s six-week abortion ban on people with high-risk pregnancies in the state. Dr. Verma has traveled the country training physicians on building evidence-based skills for effective conversations about abortion and has spearheaded ACOG efforts to support physicians and their institutions post-Dobbs.
Take five minutes to hear Verma’s masterpiece of equivocation as Hawley drills into her asking if men can get pregnant. Verma refuses to answer the question with a straightforward “no,” because she doesn’t want to get into trouble by denying that trans-identified women (also known as “trans men”) count as what most people think of as “men”, and thus some “men” can get pregnant. It’s painful to watch Verma squirm and wriggle, all because she wants to equate “identity” with biological reality. Hawley even gives her an opening, referring not just to “men,” but biological men. If you use the biological construal, then of course “men” cannot get pregnant. But Verna still won’t even answer that unambiguous question, accusing Hawley of trying to be “polarizing”. Perhaps he is, but he is on the right side in this exchange.
This question is a byproduct of Hawley trying to emphasize the dangers of medications designed to produce abortion (“abortifacients” like mifepristone and misoprostol). These are generally quite safe, which is why they’re widely prescribed. And, as someone who’s pro-choice, I have no problem with these drugs, and probably agree with Verma on this issue. Hawley is trying, however, to attack her credibility by trying to pin her down on the biological definition of “woman.” She comes off looking ideological rather than “science based.”
Verma would have been much better off had she answered this way:
“If one adheres to the biological definition of ‘woman’ and ‘man,” involving reproductive systems, then no, men cannot get pregnant. Some people believe, however, that biological women who identify as men, called ‘trans men’ or ‘trans-identified women’, also count as ‘men.’ If you have that construal, which is really gender-based and not biology-based, then yes, some people who identify as ‘men’ can get pregnant.”
But she can’t answer that way because even saying this palpable truth is enough to get you deemed a “transphobe” by “progressives”. (I speak here from personal experience.)
I’ll add that self-identification equates to biological reality only when sex is involved. As Rebecca Tuvel found to her dismay, progressives won’t allow you to identify as a member of a race or ethnic group different from your natal group. Nor can you do it with age, or height, or anything else. I am still mysified why equating self-identity with biological reality is possible only when sex is at issue, not age, race, or species.
But I digress. Listen to Verma embarrassing herself below. This is what happens when you equate sex with gender, and I urge fellow scientists not to conflate the terms this way, for the public will not be fooled.
Here are the YouTube notes:
Sen. Josh Hawley (R-MO): “Can men get pregnant?”
Dr. Nisha Verma: “I’m not really sure what the goal of the question is.”
Hawley: “The goal is just to establish a biological reality. You said just a moment ago that science and evidence should control, not politics. So, let’s test that. Can men get pregnant?”
Dr. Verma: “I take care of people with many identities…I’m also someone here to represent the complex experiences of my patients. I don’t think polarized language or questions serve that goal…
” Hawley: “It is not polarizing to say that there is a scientific difference between men and women…It is not polarizing to say that women are a biological reality and should be treated and protected as such.”
After I wrote this, I asked Emma Hilton if she’d seen the video and of course she had tweeted about it. Emma’s a bit more charitable than I, but is clear-eyed about Verma’s moment in the spotlight. Coincidentally, both of us confected what Verma should have said. I still have no idea if Verma really believes what she says, or is playing to the progressive public.
I don’t know how many times Agustín Fuentes, an anthropology professor at Princeton, will keep repeating the same arguments about why biological sex isn’t binary (see these posts on my site). It never seems to end. You’d think he’d stop banging the drum now that he’s written a whole book on the issue called Sex is a Spectrum, but he keeps on making the same old arguments that have been refuted many times (see this review by Tomas Bogardus, for example). Why does someone make such weak arguments, and continue to do so without ever addressing the many criticisms he’s encountered?
I strongly suspect it’s because Fuentes is an ideologue: he believes that if people see biological sex as spectrum rather than a binary, opprobrium against trans people will lessen or vanish. But trans people should be treated with respect no matter whether or not sex is binary, for “is” does not equal “ought”—a lesson Fuentes should have learned. Further, nearly all trans people implicitly accept a sex binary: after all, they transition from having a male role or appearance to having a female role and appearance, or vice versa. But I’ve written about that before. Nor does the binary nature of sex have anything to say about how we should regard people of nonstandard gender.Making that argument is another violation of Hume’s Law.
Now Fuentes has been joined by Nathan Lents, a professor at John Jay College. Lents has done good work refuting Intelligent Design, and I’m sad that this essay, published in ProSocial World, an endeavor of biologist David Sloan Wilson and colleagues, is not of Lent’s usual quality. In fact, it’s a terrible article, replete with mistaken arguments and bad logic.
Now it’s possible that these authors really believe that biological sex is a spectrum and are not just trying to buttress a “progressive” gender ideology, but I would find that behavior obtuse. Read Dawkins (link below) or Bogardus to see why.
I am so tired of this misrepresentation and confusion that it deeply nauseates me to have to discuss them again, but I’ll try to do so briefly, using quotes from the article by Fuentes and Lents. Click on the headline below to read (it’s also archived here).
Fuentes and Lents (henceforth F&L) first admit the binary of gametes, a binary used to define the sexes by most biologists who aren’t ideologues:
The major clades of eukaryotes – plants, animals, fungi, and the many kingdoms of protists – have evolved both unique and shared aspects in their sexual reproductive mechanisms, but one such aspect – the differentiation of gametes into two major forms – is a common theme. Anisogamy, the property of having two types of gametes – one very large and relatively immotile and one very small and highly mobile – is a key feature of sexual reproduction in all animals, all land plants, and many protist kingdoms.
F&L’s beef is not that there is a gametic binary (see Richard Dawkin’s great Substack essay for why defining—actually, recognizing—the sexes this way is essential and useful), but rather that organisms recognized as “male” (small mobile gametes) and “female” (large immobile gametes) show variation in other traits related to sex. On average, human males differ in body size from females, but there is variation within each sex. And so it goes for body hair, gene expression, behavior, penis size, and so on. But of course these traits, while correlated and connected with sex, are not part of the definition of sex, which involves the gamete binary.
Some quotes from F&L:
In our view, this binary classification of sex in animals is insufficient for capturing the full breadth of biological sexual diversity.
Some of the inadequacies of the binary sex classification for individuals are uncontroversial, as it has long been known that a large number of species – around 20% of non-arthropod invertebrates – include individuals that are simultaneously hermaphroditic. Many others, including around 2% of vertebrates, are sequential hermaphrodites. Animal bodies exist in a variety of sexed forms, with some even reconfiguring their biology relating to sex, including for the production of gametes, within their individual life history, sometimes multiple times. The presence of simultaneous and sequential hermaphrodites vexes the binary classification for sexed bodies and demonstrates that sex is neither immutable nor neatly reducible to gamete production.
Furthermore, sexual dimorphisms, sexual bimodalities, and a spectrum of sex-influenced gene expression are observed throughout animal bodies and across animal species. Some of this variation is patterned in close association with gamete production, but much is not so simply described. Across bodies, behaviors, and physiologies, there is substantive inherent variety and diversity, creating a sexual continuum of genetic, developmental, and behavioral biology within and across species. Individual animals can vary widely in the development, patterning, and expression of sexual biology in a variety of ways, from body sizes and compositions, to color patterns and genital anatomy, to courtship behaviors and parental investment, to name some of the most commonly diverse components of sex. These biological variations rarely collapse into two discrete sex-based categories defined by gamete production. Moreover, much of the biological variations in bodies, even those closely associated with reproduction, are also engaged in a diversity of other bodily functions and processes with myriad phylogenetic, ecological, and behavioral constraints and affordances, which are also not ubiquitously or consistently associated with the type of gametes a body produces.
But nobody contests this form of variation; but to pretend that hermaphrodites refute the sex binary is disingenuous. Yes, some individuals can make both types of gametes, and some, like the infamous clownfish, can actually change their sex, but the gametic binary remains. (I don’t much care if you call hermaphrodites a “third sex”, but they still bear only two types of gametes—the only types that exist.) Human hermaphrodites, like other individuals called “intersex,” are vanishingly rare, and none have been able to produce viable gametes of both types. But F&L’s arguments are not about hermaphrodites or “intersex” individuals with differences in sex development. Instead, their arguments are about variation among individuals, most of them of regular sex.
They also extend their argument among species. In various species of animals, for instance, biological sex can be determined by genes, chromosomes, rearing temperature, social milieu, haploidy versus diploidy, and so on, but there are only two types of gametes and reproductive systems, no matter how sex is determined. That in itself should tell you something important about the binary. Nevertheless, F&L persist with their “variation means there’s no binary” argument:
Dramatic sexual diversity and variation is not limited to adulthood. There is also substantive diversity in mechanisms of sex development across various animal taxa. There are chromosomal systems, other genetic systems, as well as systems based on season, temperature, age, social status, and population density, most of which have convergently evolved in multiple disparate lineages, emphasizing the relative genetic, cellular, and developmental flexibility and adaptability of these sex systems.
But, to paraphrase Ronald Fisher, the sexes are always two. Why is that? F&L are using a familiar but misguided tactic trying to refute the sex binary. I call this “The Argument from Complexity” and it can be stated this way:
There is variation among individuals in traits related to and correlated with gamete type, and that variation is often not binary but bimodal or even forming a spectrum. Further, the determination of these traits, like body size or behavior, depends on a complex interaction between genes, development, and the environment. Therefore biological sex itself is not a simple binary, but a spectrum.
You can recognize the fallacy in this; I believe Emma Hilton calls it a “bait and switch”. Yes, determination of ovaries and testes itself is complex, with many genes (as well as the internal environment) involved. And individuals vary in gene expression, body size, ornamentation, and other traits connected with sex. But there are still only two types of gametes and two sexes. Male and female peacocks look very different, but nobody says that refutes the sex binary. (In fact, the sex binary explains this difference.) And individuals of the two sexes must mate with each other to produce offspring—save for parthenogenetic or self-fertilizing species, which still participate in the gamete binary. Regardless of the complexity of development in humans, you get an offspring only when a male having sperm mates with a female having eggs. If the male is very short, or has a tiny penis, that makes no difference!
Here’s F&L’s version of The Argument from Complexity:
Importantly, the recognition that sex can be a complex mixture of anatomy, physiology, and behavior does not serve to deny or minimize the existence and impacts of sex differences. In fact, it affirms them and emphasizes their importance. While the matter of which gamete an animal body makes – its gametic sex – is clearly important, it is not the only variable by which animal morphologies or behaviors can be, or are, sexed. If these other variables were neatly binary, immutable, and non-overlapping, it would not be necessary to distinguish between gametic sex and biological sex. But, since nearly all other sex traits are either continuous or bimodal, are not always immutable nor perfectly correlated, a simple and categorical definition of sex that is based purely on gamete production is both unwarranted and potentially misleading.
. . . Animal morphology and physiology are the product of complex interactions of biological, developmental, and environmental systems, and the human environment is a particularly complex assemblage of biotic and abiotic factors: what we refer to as human culture. Human phenotypic expression is always mutually shaped by cultural milieu. It is well-established that adult height and weight, childhood development trajectories, taste bud reactivity, muscle development and coordination, patterns of sexual arousal, resistance (or lack thereof) to disease-causing bacteria, and nearly every other aspect of human bodies emerge from mutual and interactive development of physiology, morphology, cultural context, and lived experiences.
All that is sand thrown into the eyes of the public; it has nothing to do with the binary nature of biological sex.
Finally, N&L even make the bonkers argument that the athletic advantage of males or females may not be a result of their evolved differences (based on gene expression), but could be a result of social conditioning. This is an argument made by those “progressive” individuals who think that we should not be dividing sports into male versus female leagues. (The Olympic Committee has just decided otherwise.):
Furthermore, it is not currently known which, or how much, of all of this patterned variation is shaped by differences in how boys and girls, and men and women, use their bodies on a daily basis. While human anatomical development is a fairly canalized pathway producing a relatively consistent phenotypic range, the developmental process itself both affects and is substantively affected by how that anatomy is physically and socially engaged, especially during childhood and adolescence. Indeed, there is emerging evidence that persistent culturally mandated gender differences in play behaviors and sports participation, which are quite substantial in many cultures, have clear and strong effects on the developmental dynamics of skeletal and muscle formation.
Similarly, gendered differences in the social environment likely contribute to differences in sexed bodies in ways that are probably impossible to untangle. For example, it is well established that hormone levels and ratios are affected by the social environment, and these same hormones directly impact both the development of many tissues and sex-related and non-sex-related behaviors (muscle hypertrophy, hair distribution, metabolism, mental alertness, and libido, to name a few). Such complexities are not limited to humans by any stretch, as Patricia Brennan explains in another essay in this series, in Ruddy Ducks, social interactions directly impact the seasonal growth and development of the penis, emphasizing the dynamically responsive nature of sexual anatomy, even in adult animals.
It’s not clear to me what the penis of ruddy ducks has to do with human behavior and sports participation. Sadly, F&L don’t discuss the evidence that even injecting biological males with hormones and giving them puberty blockers, an important change of internal environment, nevertheless still gives these trans-identified males an athletic advantage over biological women.
I hope that I don’t have to make these points again, but I suspect I will. The ideological termites have dined well, and have even managed to convince biologists and science popularizers like Steve Novella and Bill Nye that sex is a spectrum. Have a look below at Bill Nye using the Argument from Variation to claim that sex is a spectrum. (I have never liked his arguments, and this bit shows he’s drunk the Kool-Aid.) Nye also notes that sex is “assigned at birth”. What is extra confusing is that he conflates sex with both “sexuality” and gender.
This op-ed piece in the San Francisco Chronicle is by two academics, Joan Roughgarden, whom people here might know (I reviewed her book Evolution’s Rainbow in the TLS), and Jaimie Veale, who are identified in the piece like this:
Joan Roughgarden is a professor emerita in the Department of Biology at Stanford University and author of “Evolution’s Rainbow: Diversity, Gender and Sexuality in Nature and People.” Jaimie Veale is a senior lecturer at the School of Psychological and Social Sciences at the University of Waikato in New Zealand and a past secretary of the World Professional Association for Transgender Health.
As Wikipedia notes, “In 1998, Roughgarden came out as transgender and changed her name to Joan, making a coming out post on her website on her 52nd birthday.” Jamie Veale‘s gender is not public, but she (Wikipedia refers to Veale as “her”) is described as researching transgender health and other issues. But their own identification, while perhaps motivating the thesis of this short letter, is hardly relevant to discussing the issues below. Click the headline to get the archived version, as the Chronicle’s own version is paywalled.
Roughgarden and Veale (henceforth “R & V”), make a number of statements, some of which I agree with and other which I don’t, but overall they made me think about the differences between (biological) sex and gender.
First, they agree that sex is defined by gamete size, something that Roughgarden, to her credit, has always admitted:
Zoologists, botanists, ecologists and evolutionary biologists generally define sex in this way: males make small gametes (sperm), females make large gametes (eggs) and hermaphrodites, such as most plants and many marine animals, make both.
Many animals change sex, such as coral reef fish that switch from making sperm to making eggs, or the reverse, during their lives. In turtles and other reptiles, sex is determined by the temperature at which eggs are incubated. Thus, sex may be determined well after conception according to social and environmental circumstances. And in humans, gamete production does not occur at conception. Various precursor stages appear in the fetus weeks after conception and gamete production awaits puberty.
I would note, though, that sex in humans, which is what everyone’s interested in, is determined at fertilization: whether or not the fetus has the Y-linked SRY gene that is the trigger male development.
But they also claim that every trait other than gamete size is not part of sex but is part of gender:
Beyond gamete size, everything else — including secondary sex characteristics, body size, shape, color, behavior and social roles — is gender.
Gender in nature is also extraordinarily varied and fluid across plants and animals, including humans. Beyond gamete size, no general binary describes how living things look, act or relate to others. Across species, gender difference ranges from penguins with near identical male and female genders to the extreme dimorphism of lions. Human gender diversity is in the middle, showing some gender difference that varies within and across cultures.
Thus whether or not you have a penis or vagina (secondary sex traits) are, assert R&V, part of your gender, even though their presence, and the other traits mentioned, are highly correlated with biological sex. The idea that physical traits are part of gender seemed wrong to me, but the notion of what “gender” really is has eluded me for a long time. So I thought about why it seemed wrong to call physical traits parts of gender instead of sex (behavior, as I note below, is a partial exception). This led me to come to my own tentative definition of gender.
The first thing I did, of course, was look up “gender” in the Oxford English Dictionary. Virtually all the definitions had to do with the classes of nouns in languages in which words have genders, like French and German. But there was one related definition that did correspond pretty closely to what I see as gender: gender identity.
An individual’s personal sense of being or belonging to a particular gender or genders, or of not having a gender.
Gender identity is generally regarded as distinct from biological sex, or sex as registered at birth. In later use it is also often (and for some commentators controversially) distinguished from gender as a socially or culturally constructed state (cf. gendern. 3b), and from its manifestation in gender expression or presentation (see gender expressionn., gender presentationn.).
Thinking further, it seemed to me that gender identity (what people mean when they self-describe their gender) is a psychological rather than a physical trait: it is how someone feels vis-à-vis where they lie the spectrum between being masculine or being feminine. Or perhaps they feel they aren’t on that spectrum at all, or are somewhere in the middle. Now of course in this sense gender can be described as “biological,” but only in the sense that all human thoughts and feelings are biological because they reside in the neurons of the brain. But otherwise, you can’t tell someone’s gender by their behavior, genitalia, body size, etc. You can’t tell what self-conception a person has who possesses a penis and a beard, because you can’t see inside their brain. Most such people, of course, are of male sex and feel themselves to be pretty close to male on the psychological spectrum, but traits besides gametes are not dispositive of gender. You would find out someone’s gender not by observing them, but by asking them.
Behavior is a slightly different issue since behavior issues from one’s self=conception. So R&V are correct in saying that historically, different genders have characterized many societies—though I’m using gender in my sense and not theirs:
Across cultures and through time, societies included people corresponding to what the West now calls trans or gender diverse. Anthropologists and historians documented these people across North America, South America, Polynesia, India, Southeast Asia, ancient Rome and other parts of the world. Many cultures accepted these individuals as simply part of everyday life, often holding respected social and spiritual roles unique to their cultures.
I agree with them so long as you consider gender a psychological and not physical feature, and one that can but not necessarily is expressed visibly through behavior. In other words, gender is your self-identification in terms of how you fit on the sex spectrum (or off it), and gender roles are how those self-identifies are acted out in society.
But I disagree with the authors on two issues. First, on their claim that gender identity should somehow be recognized by the courts:
In matters of law and policy, “sex” actually refers to elements of gender because the criteria that have historically determined one’s “legal sex” (typically genitals, chromosomes, appearance and/or behavior) are properties of gender and not sex. As such, the courts should recognize that legal sex encompasses gender diversity.
The authors aren’t clear about this, but it could mean that they think that biological males who identify as being women should be able to enter women’s spaces, including prisons or sports leagues, or have a right to do rape counseling if a woman wants a biologically female rape counselor. If that’s what they mean, then no, you need to recognize biological sex alone rather than gender. But I do agree with the authors’ final statement that you should follow the Golden Rule when it comes to gender identity: treating others as you would like to be treated if you were such people. (The exception, of course, are the stuff like sports and prisons).
Second, the authors seem to imply that “affirmative care” (they call it “appropriate care”, though I’m not sure that’s what they mean) is mandated for all young people suffering from gender dysphoria:
If “appropriate care” means “psychological care up to a certain age—the age when those with dysphoria can decide whether to take hormones or undergo surgery”—then I agree. But if they mean “affirmative care,” in which the wishes of children or adolescents are accepted and acted on therapeutically and medically, then I disagree. I favor “objective” therapy, not “affirmative” therapy, but therapy done with empathy. But I do not sign onto the use puberty blockers or surgery until a patient is of an age of consent (18 or 21; I waver).
I find the article confusing, both in R&V’s definition of gender and in how they want it to be used in law. There are some people—I believe Alex Byrne is among them—who say that gender is really a word that has no real meaning (it’s analogized to a “soul”). But there is still the phenomenon of people who don’t feel they adhere to concepts of masculine or feminine psychology, and I’m groping to find a definition of “gender” that can describe such people. (Most of them are, of course, biologically male or female using the gametic definition.)
Feel free to give your own take on gender in the comments. But remember, be civil and don’t call anybody names!
Here’s a 1.5-hour interview of biologist Carole Hooven by the Free Press’s Coleman Hughes. As you may know, Hooven got her Ph.D. at Harvard, started work as a teaching fellow in biological anthropology, and subsequently wrote the excellent book T: The Story of Testosterone, the Hormone that Dominates and Divides Us(2021). She was apparently a superb and popular teacher, nabbing a lot of teaching awards. But then the downfall: she got into trouble after she went on a Fox program and spoke the truth, asserting that there are two biological sexes—carefully adding the caveat that pronouns should be respected and that people with non-standard genders should be treated equally. (You can see the 4-minute Fox interview here.)
But of course the assertion that there are two biological sexes, although true, gets you labeled a “transphobe” (even with the proper caveats), and the DEI people in Carole’s department eventually made it impossible for her to work there, so she left. Harvard should be ashamed of this, and the school has done nothing to rectify its misbehavior. Subsequently, others have been demonized or called “transphobes” for defending the two-biological-sex fact. The demonizers, which include people like Steve Novella and the co-Presidents of the Freedom from Religion Foundation, should also be ashamed of their misbehavior, but they are seeking props for putting ideology over biological truth.
Carole begins by recounting her checkered—or should I say “diverse”—career, describing what happened at Harvard, and then explains the gametocentric definition of sex rejected by gender ideologues. The rest of the interview, with both discussants showing their characteristic eloquence, is a biology lesson, a lesson on sex determination, what can go wrong with the “normal” forms of development, and how evolution has produced differences in the morphology and behavior of the two sexes. Testosterone naturally makes an appearance. You can see why Carole won so many teaching awards.
The YouTube notes are these:
In elite circles, it has become strangely difficult to say out loud what every biology department taught as recently as 10 years ago: that sex is binary, that testosterone matters, and that average differences do not mean categorical rules. That’s why I wanted to sit down with Carole Hooven, an evolutionary biologist who spent 20 years at Harvard teaching hormones, behavior, and evolutionary psychology before she was pushed out for stating precisely that.
In our conversation, Hooven traces how she got here: from her early fieldwork studying chimp aggression in Uganda, to her best-selling book on testosterone, to the moment a single Fox News clip triggered a campus-wide effort to paint her as “dangerous.” She explains what research actually says—about rough-and-tumble play, aggression, libido, and the long-run effects of puberty blockers and cross-sex hormones—and how activists and journalists systematically mislead the public.
Hooven isn’t angry or ideological; she is empirically careful. She draws a distinction almost nobody in public debate seems capable of holding anymore: Sex itself is binary, but sex-associated traits form overlapping distributions. Confusing those two ideas is what produces so much intellectual chaos and so much institutional cowardice.
This episode challenges the comforting myths: that these debates are “just semantics,” that biology can be legislated away, and that open scientific inquiry can coexist with fear of one’s students. What Hooven makes clear is that the science hasn’t changed, only the cost of talking about it.
