Carole Hooven in Tablet on binary sex

September 26, 2025 • 9:30 am

Dr. Hooven (“Carole” to me) has a new piece in Tablet (click headline below to read for free) explaining why all sensible biologists see sex as a binary defined by two (and only two) types of gametes. Perhaps you’ll already be familiar with some of her arguments in the article below (click to read), as I’ve written extensively on the topic. But she adds some good angles in the piece, which she ties together by reporting how she was forced to leave Harvard because her department couldn’t abide her teaching that sex was binary (see her story here).

The impetus for the Tablet piece begins with Agustín Fuentes’s recent book Sex is a Spectrum: The Biological Limits of the Binary, a book that is ideologically rather than scientifically based (see my own short review here and another critical review here). It’s simply a bad and misleading book. And, like so many other people denying the binary nature of sex, Fuentes is motivated not by any new scientific developments effacing the binary, by rather by ideology: if he and others are able to say biological sex is not a binary but a spectrum, it supposedly gives succor to those who don’t identify themselves as “male” or “female”. This motivation becomes clear in Fuentes’s last chapter. (Please note that the concept of “transsexual” implicitly assumes a sex binary, as there are only two ways to transition.)

Carole was inspired to write her piece, however, by a positive review of Fuentes’s book in Lancet, written by Sarah Richardson—a Professor of the History of Science and Professor of Studies of Women, Gender, and Sexuality at Harvard, as well as director of the Harvard GenderSci Lab. She was a colleague of Hooven but they have clearly parted intellectual ways. (See my take on Richardson’s piece here,). Richardson’s review, also attacking the binary, is not only ideological, but also mean-spirited, attacking the motives of those who tout the sex binary. (See below.) My report on Richardson’s misguided piece gives a screenshot of her review as well as some of Carole’s tweets that gave rise to her Tablet piece.

As Carole says in her new piece, Richardson prefers to attack the binary people (we can call ourselves “anisogamists”) on ideological rather than scientific grounds. We are, Richardson avers, motivated by a desire to erase trans and nonbinary people. That is dumb; none of us want to do that!

A quote from Hooven in Tablet:

Richardson not only thinks the “gametic” definition of sex is wrong; she also insists that its adherents have sinister political motives:

Although the gametic definition makes reference to biological systems, it is sophistry, not science. Those who promote this definition favour the assertion that sex inheres in gamete (sperm and egg) production because, in part, it facilitates their political aims by fuelling unhinged panic in some quarters about transgender threats to traditional gender roles. … Like scientific bigots of yore … the recent favour bestowed on [this] definition of sex … appeals selectively to science to naturalise and rationalise inequality and exclusion.

Richardson goes on to praise Fuentes for recognizing scientists’ “responsibility to respond to harmful deployments of inaccurate, overly simplistic, and reductionist science by those attempting to naturalise and depoliticise their hateful views.”

This is intellectually dishonest in the sense that many anisogamists, including me, favor trans rights (though they are limited in a few respects, involving things like sports participation and prisons). It’s even more dishonest in that previously Richardson herself had promoted the sex binary. To wit: a tweet from philosopher Tomás Bogrdus, followed by the first of four critical tweets by Hooven:

It gets more awkward for Richardson. In this 2025 review, Richardson says the gametic view of the sexes is sophistry, and those who promote it are motivated partly by bigotry.

Buuuuut in her own 2013 book, Sex Itself, Richardson seems to promote the gametic view. See attached. https://t.co/IxpFAGwVrb pic.twitter.com/xu8YsOUKbd

— Tomas Bogardus (@TomasBogardus) August 6, 2025

Since there have been no important advances in sex concepts based on science in the last 12 years, we can hypothesize that Richardson changed her views on the binary to conform to the Zeitgeist: in this case to the rapid increase of people who see themselves as nonbinary, and whose self-identification must be considered sacred.

Now Carole is extremely nice and her Tablet piece, while pointing out the misguided rancor of Richardson, is itself perfectly polite, sticking to the facts. One thing I like about it is how she introduces the binary, not simply by asserting the universality of only one distinction between males and females (gamete type) or of the utility of a binary concept (see Dawkins’s piece here for that), but through the act of sexual reproduction itself. This then naturally segues into the gamete binary. The bolding in Carole’s excerpt below is mine.

The question of how to define sex is not a new one, but the answer has taken on new urgency, given its implications for areas such as law, public safety, healthcare and sports. Despite the urgency, the correct answer has been understood since the late 19th century.

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.

Hooven herself segues into the implications for science education, and mentions Harvard’s “kick in the pants” by the Trump Administration:

What happens on campus and in scientific journals carries tremendous influence beyond the academy. So when those institutions promote this kind of pseudo-debate and name-calling over consensus science, knowledge is subordinated to political goals. When a prestigious university signals that a scientifically grounded view is socially radioactive, that framing leaks into the wider culture—into media, politics, and policy. Soon, an orthodox fact becomes unsayable in polite company, making it harder to have good-faith public debates and contributing to political extremism.

. . . Harvard has made some meaningful and positive changes that are designed to increase viewpoint diversity, including the abolition of mandatory DEI statements in hiring and the adoption of an institutional neutrality policy, which prohibits the administration (from department chairs to the president) from issuing public statements on issues not directly relevant to the core mission of the university. More recently, under pressure from the federal government, DEI offices have been rebranded, statements about the importance of viewpoint diversity have been issued, and committees established to investigate and report on other problems with campus culture (most concerning bias on campus in the wake of Oct. 7). While these changes are positive, they should not have been necessary, nor should extreme external duress have been required to prompt them.

It’s unfortunate that Harvard’s kick in the pants had to come from the federal government. The punishments levied, including a freeze on more than $2 billion of research grants, may be illegal and vastly out of proportion and will likely do more harm than good. So while Harvard is right to fight back, it would be wrong not to use this as an opportunity to make substantive changes.

Apparently Tablet approached Carole to turn her Twitter posts into this article.

You can read the rest for yourself, but she told me to pay special attention to the video in the second link below. I’ve put the video below to save your having to click (the link is in a discussion of Richardson’s position at Harvard):

[Richardson] is also the head of Harvard’s GenderSci Lab, whose work aims to “counter bias and hype in sex difference research, elevate the importance of context, contingency, and variation in the study of gender and sex in biology … and engage the implications of biological claims about gender and sexual diversity for law and public policy relevant to the lives of gender and sexual minorities.“

The YouTube notes on the video describe it this way (you can read more about Lett here):

Sarah Richardson, PhD, Director of the GenderSci Lab at Harvard University and Elle Lett, PhD, discuss what there is to be hopeful about in the science of gender and science in early 2025 at an Intersectionality Research Salon.

Note that Lett praises Richardson for helping “craft the world we want to see. . . through science.” And Richardson makes no bones about using her work to put out “messages” that, to me, are apparently “progressive” messages. One senses not a motivation to seek the truth, but to buttress those seen as oppressed.

You can of course use science to better the world in a direction that you want. Innovations in medicine, like mRNA vaccines, is one example. But what you can’t do, and what Richardson and Fuentes are trying to do, is to bend science out of shape, pretending that it conforms to and buttresses a particular ideology. (This is what I call “the reverse naturalistic fallacy”.)

Not only do Fuentes and Richardson twist the science, but their harmful activities extend to mischaracterizing their opponents as bigoted transphobes. That, they must surely know, is wrong. But when you can’t attack your opponents’ facts, you can always attack their motives.

Now it hasn’t escaped my notice that I myself characterize Richardson’s and Fuentes’s motives, but they’ve been pretty transparent about them. And besides, we have the facts on our side, facts I’ve adduced many times. Sex is binary.

Democratic candidate for U.S. Senate seat in Texas says that there are six biological sexes

September 19, 2025 • 10:00 am

You may remember the attack ads on Kamala Harris put out by Trump’s team during the last election. Some of them singled out her statement that the government should fund gender transitions for prison inmates, while others mentioned that Harris wants to “allow biological men to compete in womens sports” (see video in tweet at bottom). Most of these ads ended with the mantra: “Kamala is for they/them, President Trump is for you.” I have to admit that that’s a clever ending, though I dislike the general anti-trans tone of the ads. While I agree that trans-identified men (biological men) should not compete in women’s sports, these ads, aimed mostly at young men, rest heavily on a Republican foundation of anti-trans bigotry rather than on reasoned discussion of whether men should compete against women in athletics or whether taxpayers should fund gender changes.

Did the ads work? (There’s even a Wikipedia page on them.) Both that page and a HuffPo article show that the ads might have been effective in converting swing voters to Trump, but, on the other hand, might not have been. The evidence is mixed, though it’s pretty clear they didn’t clearly hurt Trump or help Harris.

From Wikipedia:

The ads, which had several different variations, aired more than 30,000 times in every swing state. The Trump campaign put the ads in heavy rotation during televised NFL and college football games and NASCAR Xfinity Series races. According to an analysis by Future Forward, a Democratic super PAC, “Kamala is for they/them” was one of Trump’s most effective 30-second attack ads, shifting the race 2.7 percentage points in favor of Trump after viewers watched it. Conversely, an RCT study by Ground Media released by GLAAD, an LGBTQ media monitoring organization, stated that the ad did not have an impact on who viewers intended to vote for.

HuffPo (the surveys are different from those given above):

Republican ads suggesting Vice President Kamala Harris cared more about promoting transgender rights than boosting the economy likely contributed to Donald Trump’s victory, according to a new survey conducted after Tuesday’s election.

Another poll released this week by a different Democratic firm found, however, that hardly any voters were motivated by opposition to transgender surgeries or what Republicans derisively call “boys in girls sports.”

Here’s a video from Reuters discussing these ads:

The video says that Trump’s ad campaign was “against transgender rights”, suggesting that it was about more than sports or funding gender change in prisons. But these are only two forms of “transgender rights”, and for nearly every other right, I’ve argued that transgender people should be treated the same way as everyone else. But because of the conflation of these different “rights,” and the fact that trans issues aren’t on most voters’ radar (voters care more about their own economic well being), it’s probably best for the Democrats not to pronounce on trans sports participation—or to proclaim that there are more than two sexes. And the number of biological sexes happens to be the subject of this post.

Some Democrats, it seems, just can’t seem to stay away from crazy pronouncements about sex and gender, and that could hurt us in the midterm elections. If I were a Republican, I would ask my opponent to tell me how many biological sexes there are. If they say anything other than two, they look mushy and woke, sort of like the Society for the Study of Evolution.

Reader Robert called my attention to the Substack post below by Josh Barro. reporting that the leading Democratic candidate for the upcoming Texas Senatorial election is saying things like “there are six sexes” (yes, six) and that “God is nonbinary”. Click the screenshot to read:

Who’s author Josh Barro? He’s described by Wikipedia this way:

Barro has expressed heterodox political views, and has criticized both major parties.

. . .On October 11, 2016, following the Republican Party’s nomination of Donald Trump for president, Barro said he had left the Republican Party and registered as a Democrat. Barro cited as reasons for his decision the “fact-free environment so many of its voters live in, and because of the anti-Democrat hysteria that had been willfully whipped up by so many of its politicians,” which created a “vulnerability in our democracy.”

In November 2024, after Democrat Kamala Harris was defeated by Trump in the 2024 United States presidential election, Barro published a column entitled “Trump Didn’t Deserve to Win, But We Deserved to Lose,” wherein he broadly criticized the Democratic Party, including Democratic governance of New York City, where he lives. Barro particularly criticized Democrats for ineffectively responding to issues such as inflation and immigration, adding, “I am unfortunately a Democrat.” In February 2025, he wrote that “[t]he woke brigades in the Democratic Party aren’t merely annoying. They have undermined Democrats’ appeal to the same minority communities they are supposedly so focused on ‘including.’ “

Barro, then, seems to be a moderate Democrat who shares some of my opinions on the election. And his column is largely about the Texas Senatorial candidate James Talarico, described this way:

. . . . an American politician, Presbyterian seminarian, and former public school teacher serving in the Texas House of Representatives since 2018. He is a member of the Democratic Party and has been called a “rising star” among Texas Democrats.

. . . .. In September 2025, Talarico announced his candidacy for the 2026 US Senate race in Texas.

In that election Talarico, should he win the Democratic primary, will face John Cornyn, a Republican who has held a Texas Senatorial seat since 2002, and is now senior Senator above Republican Ted Cruz. Given that no Democrat has won a U.S. Senate seat from Texas since 1990, Talarico, who won his state House seat handily, seems unlikely to repeat that win for a U.S. Senate seat. But we need all the seats we can get in the Senate, and Talarico isn’t helping himself, at least according to Barro:

. . . And yet the new hotness in Texas is James Talarico, a handsome 36-year-old Presbyterian seminarian who represents part of Austin in the state legislature. He’s undeniably charming, and he’s gotten a lot of mileage out of a recent appearance on The Joe Rogan Experience. But he’s a liberal’s idea of what a conservative might like: A clean-cut young man who’s adept at quoting scripture in support of a conventional set of liberal policy priorities.

As his primary opponent Terry Virts has pointed out in a short attack video, Talarico has one particular liability related to this that sticks out like a sore thumb. He made a bunch of out-there comments about sex and gender at a hearing where he argued against legislation that would have set a (widely popular) restriction limiting girls’ sports at schools in the state to female participants. At the 2021 hearing, Talarico offered a bunch of ideas about how both science and scripture cut against such a rule.

“Modern science obviously recognizes that there are many more than two biological sexes,” he declared. “In fact, there are six.”

“God is non-binary,” he said, with unintentionally comical gravity, in another speech about the bill. I really suggest watching the video to get a sense of how these quotes are going to be clipped into highly effective attack ads if Talarico becomes our nominee in this race.

(The video of Talarico’s remarks is below.) Shoot me now! What six biological sexes does Talarico favor? I want to know! And as for God being nonbinary, well, for an atheist like me that’s a non-starter, but even if you’re religious, how can you claim that God is “nonbinary”. The only evidence is against that: in the Bible where God is always referred to as “he”. Barro goes on:

Virts, a former fighter pilot and astronaut who once commanded the International Space Station, has a clear argument about what’s wrong here: These arguments are out of step with the vast majority of Texans. We saw with the “Kamala is for they/them” ad that attacks on this issue can be highly effective, even if the comments made on tape are a few years old, and even if Democrats think people really ought to pay more attention to Medicaid cuts. So Virts challenges Talarico: How will he respond to those attack ads that will inevitably come?

I asked the Talarico campaign that question, and they provided me a statement from the candidate that does not give me confidence that he’s prepared to go into a general election and neutralize this issue in a race against Paxton.

I reproduce it here in full:

As I’ve said before, there are two sexes and intersex people.

When it comes to trans student athletes, I believe sports need to be safe and fair. These decisions are best left up to sports leagues and local officials — not politicians — with sensible limitations on who plays in competitive leagues.

This quote — pulled out of context from a nuanced conversation about a bill that would impact Texas students — represents what our campaign is running against: the billionaires and their puppet politicians who divide the rest of us so we don’t notice they’re gutting our healthcare, defunding our schools, and cutting taxes for themselves and their rich friends.

We’ve noticed. And we’re done being divided.

The third paragraph is classic politics of evasion: a candidate responding to an attack on an issue where he is weak by saying the real issue is something else. This has not worked as a strategy for Democrats when theyhave taken unpopular stances on issues they’d rather not discuss, like crime, immigration, and what gender even is. The second paragraph, meanwhile, is an effort to fudge the question of girls’ sports by taking no position at all. This just isn’t going to be good enough to counter what voters will see in the ads: Talarico saying something bizarre, in support of an unpopular policy, in a way that shows he does not think like ordinary Texans.

It’s too late for Talarico, who is religious, to take back what he said, but his attempt to “clarify” it just muddled the issue. It’s clear that Talarico does indeed believe there are six biological sexes, but realized too late how dumb that looked to the public, and in his correction erased 67% of the sexes. The quote was not pulled out of context. See for yourself below:

Some early Dem skirmishing in this primary: @AstroTerry, a retired astronaut who has been running since June, warns that Talarico’s past statements about gender make him less electable.

Plays the 2024 anti-Harris ads and warns “the same ads will be played by Ken Paxton.” https://t.co/zCHjTAXUbu pic.twitter.com/FkaQQxL136

— David Weigel (@daveweigel) September 9, 2025

Barro goes into the intersex issue, something you can read for yourself, showing that Talarico has apparently been seduced by Anne Fausto-Sterling’s claim that 1.7% of people are intersex, a figure that’s a huge overestimate no matter what you define as “intersex”—or even if you want to use that term. Barro closes by returning to the number of sexes and sports again:

But to step back, the big political problem here is the emergent liberal instinct toward galaxy-brain, well-ackshually there are six sexes-style argumentation. We could call it the party’s John Oliver problem — some Democrats’ excessive interest in counterintuitive arguments that only impress people who start from strongly liberal preconceptions. Sex and gender are subjects that everyone has a lot of direct personal experience with. And we know, from life, that sex is by and large not a difficult concept — there are males and females and, if you look at their genitalia, it’s almost always quite easy to find out who’s what. Then, some liberal comes around and tells you he’s read The Science and everything you thought you knew about that is wrong. Sex is a spectrum and actually quite confusing and difficult to assess. In fact, there are four new sexes you hadn’t even heard of! Very complex, very complex, you see. This does not make the liberal sound smart. It makes him sound like an idiot who’s easily drawn to fashionable-but-silly ideas.

Or like Steve Novella or Agustín Fuentes or any number of misguided academics and physicians. Barro continues:

. . . .On girls’ sports specifically, Democrats’ problem is that they’ve gotten on the unpopular side of an issue by arguing for something that was never morally necessary. But more broadly, on some of these social issues, Democrats’ problem is that they have gotten attached to a way of thinking that makes them overly open to implausible claims and overly impressed by rhetorical flourishes. Addressing the problem requires pausing before one speaks to ask, “Will I sound normal if I say this? Will I sound like I’m using rhetoric to camouflage a weak idea? Will I sound like I spent too much time talking to graduate students?”

If you ask yourself those questions, you’ll never make the mistake of saying “God is non-binary” in front of a camera.

Note that Barro argues that one can recognize biological sex by genitalia, which isn’t precisely correct. It’s recognized by gamete type—large and small—and there’s a very high correlation between the gamete-producing apparatus of a person and the morphology of their genitals (doctors don’t look at gonads at birth). Beyond that, Barro is right. Democrats should not look like they just fell out of a coconut tree!

Short (?) review: “Sex is a spectrum”

September 11, 2025 • 10:45 am

Reading time: Whatever. . .

You’ll probably guess from the title of this short (150-page) book by Agustín Fuentes (Princeton University Press) that I am not keen on its thesis, and you’d be right. In fact, the thesis is nothing new, even if you have read Fuentes’s article about it in Natural History and Scientific American or the many attacks on the sex binary coming from woke but misguided people. These attacks, which assert that sex is really a “spectrum”, have also been launched by Steve Novella at Science-Based Medicine, the editors of Natural History, the Lancet, and other places that Luana and I discussed in our piece in Skeptical Inquirer (see our point #1).

In fact, it seems more common to see pieces attacking the sex binary than defending it, even though, in terms of biological sex—the binary of male and female, based on gamete type (big and immobile versus small and mobile)—happens to be true. As Dawkins and I (and others) have mentioned, it’s as close to a binary as you can get, with exceptions (“intersex” individuals) having a frequency of about 1 in 5600 or 1 in 6700, depending on how you define intersex. That is lower than the frequency of individuals born with extra or missing digits, but we don’t say that “humans lie on a digit spectrum”.

I won’t go into the numerous reasons why biologists in general see a sex binary in vascular plants and all animals; read Richard Dawkins’s eloquent exposition of the reasons here. Nor will I give a long review of Fuentes’s book, as a good critical one has already appeared, and Fuentes’s recycled arguments have been attacked by many of us. Let me just add that why this has suddenly become a big kerfuffle is not because any new biological facts have surfaced showing that animals actually have three or more types of gametes (they don’t), but because of the rise of gender ideology.

Fuentes wrote his book for the same reason that most others criticize the sex binary: because of the recent increase in the number of people who see themselves as not belonging to either sex, but lying outside the male/female dichotomy –or in between. This is gender, though, and while people do have these feelings, some of which may even have a biological basis, it does not dispel the reality of the gamete binary, which biologists seized on as the “concept” of biological sex for two reasons. First, the two-gametes reality is sole binary true of all animals and vascular plants; and second, because the binary concept is also deeply explanatory, giving insight into things like sexual selection. But because some people feel they’re not male or female, “progressive” scientists feel a duty to twist our view of nature so that sex becomes a spectrum. They may mean well, but they damage biology by misleading people about biological sex. They also damage biology by leading people to distrust it because the distorters demand that folks deny things that are palpably real.

And so Fuentes, though he feels the binary is “damaging” (his arguments are not convincing), actually does the damage himself. You can see his ideological motivation in the last two sections of the book, which deal respectively with why trans-identified males should be allowed to compete in women’s sports, and why we should not have bathrooms based on natal sex. (I happen to agree with the latter point but not the former.) But these are questions of politics and ideology, not biology.

So what is Fuentes’s argument? Again, it’s familiar. Sex as “enacted” in the real world of humans (note the concentration on humans) involve the 3 “Gs” (genitals, gonads, and genes), as well as physiology, hormones, reproductive leanings, and psychology (how one “feels”). These don’t always align perfectly, and because they don’t, sex is not binary. But this is a straw-man argument, since he’s arguing against the biological binary based on gametes, and none of us have asserted that there is always a perfect match between chromosomes, genital morphology, self-concept, physiology, and gamete type (the concordance, however, is often very high).

Fuentes raises familiar and already-rebutted arguments: fish like wrasses and clownfish change sex as sequential hermaphrodites. Bees have three types of castes, workers, queens, and drones. And so on and so on. But none of this refutes the sex binary. Fish, at a given time in their lives, produce either large or small gametes, and worker bees, as everyone with a brain knows, are females. Although their reproductive organs are underdeveloped, these organs are clearly female, and in fact some colonies of honeybees in South Africa have no queens: the normally “sterile” workers have fully developed female organs and lay parthenogenetic eggs without a need to be inseminated. Those colonies are 100% female.

Every example Fuentes gives falls into the gametic binary, and, as Bogardus’s review notes, Fuentes tacitly ACCEPTS a sex binary. Fuentes shies away from the words “male” or “female” (unless they’re in parentheses after “3G”), but instead constantly refers to “large gamete producers” and “small gamete producers”. Never does he refer to “intermediate gamete producers” or any other type of gamete producers. This is a tacit admission that sex, conceptualized through gamete type, is indeed binary.

As Bogardus said in his review (his bolding)

But there are strong reasons to deny that sex “comprises” multiple traits and processes. There is really only one trait that seems to be necessary and sufficient for being a male, namely having the function of producing a component with the function of producing sperm. And similarly for females, with regard to ova. To be “hormonally female” is to have hormone levels typical of the females of the species, but a male who has e.g. hormone levels typical of females of that species does not literally become a female in any sense of the word. Nor does he have multiple sexes, being both male and female.

Instead, what’s true is that there are many traits and processes that are linked to sex—there are a variety of sex-linked traits. But in order for these traits to be linked to sex, they must be distinct from sex. Fuentes is mistaken, then, to think that sex “comprises” multiple traits and processes: he’s confusing a multiplicity of sex-linked traits with sex itself.

Fuentes spends much of the book in a misguided quest to show that there aren’t really any biological differences between human males and females (or such differences are inconsequential), and so sex becomes a slippery concept. He never actually tells us how he defines “male” and “female”, perhaps because he thinks they don’t exist. Even differences in musculature and bones that mandate the creation of men’s vs. women’s sports, Fuentes suggests, have a social origin, perhaps based on differential training (“gendered training dynamics,” p. 143).

I can see that this is going to get long unless I bring it to a halt, and so I will. I’ll make one more point, involving how Fuentes contradicts himself—not for the first time in this book. Although he argues that any differences between men and women are “biocultural”, based on an interaction between nature and culture (he’s right for some traits), he also argues that it is imperative to take self-identified sex into account when doing medical or scientific investigations. And that is right, too: some drugs have differential effects on the sexes because of their biological differences (whatever the source of those differences). But if biology is only part of the reason for those differences, and sometimes a small one, shouldn’t we be dividing up research subjects not by biological sex, but by gender, culture, or even “lived experience”. Imagine designing a medical study based on experience!

At any rate, I’m done. I did my due diligence in reading the book, even though I already knew everything Fuentes was going to say—because he’d said it before. I’ll add that it’s not only a tendentious book, but a tedious book. The writing is poor, droning on in a hybrid popular + academic style that is hard going. Fuentes, for example, never cites one area without citing three. (Example on p. 135: “”These conditions represent complex interlacing of physiological, neurological, social, experiential, and individual processes.”) Over and over again you must slog through such sentences. The man needs to learn how to write popular scientific prose.

I’ll finish with the final paragraph of the review by Bogardus, who did much more due diligence than I (plus he’s a biologically-informed philosopher, good at pointing out and refuting muddled arguments):

Though Fuentes offers much sound and fury against “the binary view,” in the end it amounts to nothing: his thesis is either uncontroversially true or obviously false. Even worse, in tragic Shakespearean fashion, Fuentes sows the seeds of his own undoing, unwittingly supplying himself with premises sufficient to prove that the title of his book is exactly false: Sex itself is not a spectrum at all, but rather is binary.

The only thing I’ll add is that you don’t need to read this book if you already know about the “binary” controversy. Fuentes sheds no more light on it.

American Humanist vigorously endorses “affirmative care” with no lower age limit

September 4, 2025 • 10:30 am

The American Humanist Association (AHA) is among the most prominent humanist/atheist/skeptical organizations in America, but it’s been getting increasingly “progressive” (read “woke”). You may remember that in 2021 the AHA revoked its “Humanist of the Year” award given to Richard Dawkins 15 years earlier, saying this:

Regrettably, Richard Dawkins has over the past several years accumulated a history of making statements that use the guise of scientific discourse to demean marginalized groups, an approach antithetical to humanist values. His latest statement implies that the identities of transgender individuals are fraudulent, while also simultaneously attacking Black identity as one that can be assumed when convenient. His subsequent attempts at clarification are inadequate and convey neither sensitivity nor sincerity.

This is an arrant mischaracterization of Dawkins’s views, which were most famously expressed in this tweet in 2021 (note the coincidence with the year of revocation):

It didn’t matter to the AHA that Dawkins tried to explain what he meant by that tweet: it was a question intended to provoke discussion:

It didn’t matter that the Rachel Dolezal “transracial” issue is certainly worth discussing, and the first tweet above surely did not mean that Richard thinks the “identities of transgender individuals are fraudulent, while also simultaneously attacking Black identity as one that can be assumed when convenient.” That can be said only if you want to attack Dawkins to begin with or are flautning virtue at the expense of truth.

This shows two things relevant to this post: that the AHA has become overly woke, and, more relevant for today, the organization waving the banner of gender activism (here the issue of transgenderism) beyond reason, ignoring the facts. Both of these conclusions can be seen in the article below by Kavita Narayan, identified by the AHA as “a humanist writer and researcher based in LA.”.

Even though the piece is long for many people’s attention spans, I suggest you read the whole thing to check whether my assertions are correct and to see where the AHA probably stands on this issue. I assume that the AHA agrees with Narayan’s views, as she repeatedly invokes what the AHA believes to justify her conclusions, and the organization allowed her to publish the long article.

Here are some of the AHA’s assertions I’ve gleaned from the article. Bold headings are mine, Narayan’s quotes are indented, and my comments are flush left:

1.) Denying “affirmative care” to anyone (including adolescents) who wants it, with that care including hormones and surgery, is unethical.

Transmasculine and nonbinary individuals report invasive gatekeeping, as well: Jordan, 22 and nonbinary, remembers undergoing humiliating questioning before a hysterectomy consultation, a stark reflection of a system built only for cis bodies.

A humanist framework grounded in reason, equality, and bodily autonomy holds that denying care based on gender identity is not only a practical failure, but an ethical breach. “To deny someone care… is not just unethical, it’s inhuman,” says ethicist Casey Ruhl.

. . . This is where humanism can make a unique impact. Unlike traditional religions that may treat gender diversity as a moral debate, humanism begins from a different premise: that every individual has inherent worth, and that self-determination is not a privilege, but a right. “Humanism allows us to honor people without pretending to know them better than they know themselves,” says Elan, a queer humanist chaplain.

Note that they give no age limit here: any child or adolescent who claims to be of the sex different from their natal sex has a right not just to be believed, but also given affirmative care. I would add here that unless you’re “of age” (I’ll take it to be the age of 18, the legal age at which a person can make their own healthcare decisions), I would not be so quick to say that a person “knows themselves,” particularly when it comes to “knowing” that they’re really of their non-natal sex. “Self-determination” for medical issues is not a right for anyone under 18, and may not be warranted if someone wants to transition when they have other psychological issues when over age 18. Often gender dysphoria is part of a complex of other, unrelated psychological problems, problems that are often confused with gender dysphoria itself (see below). It can also be exacerbated by social pressure–the “affirmation” from peers, which is often very strong.

Finally, remember that doctors are not obligated legally to do anything that a patient wants, even if it’s harmless. If someone goes to a doctor with a viral infection and demands antibiotics, doctors are perfectly within their rights to refuse, for antibiotics are not only useless against viruses, but their wanton use can increase antibiotic resistance in bacteria. If you ask someone to cut off your arm because you think it’s superfluous (yes, there are such people), doctors can and will refuse, and will not suffer for it. And no doctor is obligated to give children or adolescents puberty blockers or hormones just because they ask for it. (A good doctor will refer such people to competent specialists.) This doesn’t mean that if someone has an easily treatable ailment or injury, it is ETHICAL for a doctor to refuse treatment, but gender transitioning does not fall into this category. It takes a specialist in pediatric gender transitioning, objective rather than affirmative therapy, and above all what we don’t have: evidence that it’s safe to use puberty blockers. After puberty is over, of course, a gender-specialist doctor can help transitioning by giving hormones and other things, though surgery is something that requires careful thought, and perhaps many surgeons won’t agree to go snipping off breasts or genitals.

2.) There is no lower age limit to begin “affirmative treatment”, and treatment that includes puberty blockers is reversible. While the article argues that gender-affirming care is safe and efficacious “when providce with informed consent”, what does that mean? If parents assent that it’s okay to inject a child or adolescent with hormones or cut off bits of their body, does that mean that a child of any age has a right to do that, so long as they find a compliant doctor? Look at the title of this section:

The Myth of “Too Young” and the Data That Debunks It

Opponents of gender-affirming care often argue that children are too young to make life-altering decisions. But this talking point misunderstands both the process and the people it affects.

Gender-affirming care for minors doesn’t begin with surgery. It starts with listening. It involves long conversations with therapists, pediatricians, and families. Puberty blockers, often the first clinical step, are fully reversible and give young people time to explore their identity without the permanent effects of endogenous puberty.

Narayan’s “myth of too young” is invidious. First, it’s not uncommon for children to be referred to doctors for affvirmative therapy or even hormones after just one or a few visits, lacking those “long conversations.”

Second, talk therapy that supports and verifies the conclusion of a young person that they are transgender should be, but is not invariably, objective. What if the therapist fails to affirm the child’s assertion, concluding that the child is too young or is caught in a morass of psychological confusion? Is that unethical?

And is “too young” really a myth? Children as young as 11 (e.g., Jazz Jennings) have taken puberty blockers, and, at 17, Jennings had the difficult and complex “bottom surgery”. Other papers report girls as young as 13 getting double mastectomies. In 2022, the organization WPATH, a villain in this narrative, recommended these things:

The World Professional Association for Transgender Health said hormones could be started at age 14, two years earlier than the group’s previous advice, and some surgeries done at age 15 or 17, a year or so earlier than previous guidance. The group acknowledged potential risks but said it is unethical and harmful to withhold early treatment.

Surgery at 15 and hormones at 14?

Note the “unethical” trope, as raised by Narayan above. As for “harmful to withhold early treatment,” it’s important to realize that the majority of adolescents and children who are not given affirmative treatment eventually come out as gay, so that neither surgery or hormone treatment needs to be done.

As I’ll mention in a minute, those treatments might damage people’s health, despite Narayan’s assertion, and we don’t know their long-term effects, except that post-puberty hormone treatment, as well as bottom surgery, can leave people without the ability to have a sex life that includes orgasms. Simply affirming a child’s self-diagnosis and giving them whatever hormones they want is bad practice without careful vetting, and certainly there are ages that are “too young” for that. (I’ve suggested a lower limit of 18, but even 21 may be okay.)

At any rate, there are a variety of studies showing the proportion of children with gender dysphoria who do not receive affirmative care and wind up deciding they’re gay. This varies from 39% to 80% among boys. Data from girls are sparser, but several studies of small samples say that untreated gender-dysphoric girls usually become lesbian or cisgender women. Given this, and the possible dangers of hormone treatment and demonstrated dangers of surgery, saying that no child is too young to be treated, and that they have a right to be treated the way they want, is, to me, both unethical and harmful. To foster the idea that there is no such thing as “too young” is pushing children to make decisions that they’re not ready to make—decisions that will change their lives and bodies forever.

As for the harm of puberty blockers when they are stopped, there is insufficient evidence about the long-term effects of puberty blockers on several traits, and some evidence that there are irreversible effects on bone density and height. As the Cass Report states:

There were no high-quality studies identified that used an appropriate study design to assess the outcomes of puberty suppression in adolescents experiencing gender dysphoria or incongruence. There is insufficient and/or inconsistent evidence about the effects of puberty suppression on gender dysphoria, mental and psychosocial health, cognitive development, cardio-metabolic risk, and fertility. There is consistent moderate-quality evidence, albeit from mainly pre-post studies, that bone density and height may be compromised during treatment.

There is a lack of high-quality research assessing the outcomes of hormones for masculinisation or feminisation in adolescents with gender dysphoria or incongruence and few studies that undertake long-term follow-up. There is little evidence regarding gender dysphoria, body satisfaction, psychosocial and cognitive outcomes, and fertility. There is moderate-quality evidence from mainly pre-post studies that hormone treatment may in the short-term improve some aspects of psychological health. There is inconsistent evidence about the effect of hormones on height/growth, bone health and cardiometabolic effects.

There is certainly not enough evidence to say that the effects of puberty blockers on the body are safe and fully reversible, although some of the phenotypic effects may be. The lack of firm evidence that blockers are irreversible and safe is one reason the puberty blockers (not approved, by the way by the FDA for blocking puberty, and always prescribed “off label”) are considered “experimental treatment” in the UK under 18, and are severely restricted in quite a few other countries like Sweden. Almost nowhere are they permitted to be given willy-nilly to children or adolescents at their request, as Narayan seems to feel.

3). Withholding affirmative care increases depression and suicidality. Affirmation is, as the article says, “life-saving”. Note that the AHA is very canny here, repeatedly using the word “suicidality” rather than “suicide”, although the general claim among gender activists is that withholding affirmative care increases suicide itself. But the American Psychological Association defines “suicidality” as “the risk of suicide, usually indicated by suicidal ideation or intent, especially as evident in the presence of a well-elaborated suicidal plan.”

The AHA says this:

Affirmation isn’t just emotional. It directly correlates with better mental health outcomes. A 2022 study in JAMA Network Open found that transgender youth who received gender-affirming care had significantly lower rates of depression and suicidality than those who did not. These effects persist into adulthood, with gender-affirming hormones and surgeries linked to improved quality of life and reduced psychological distress.

The link given doesn’t go to an article I can find, but I do know of one good study that seems to me the gold standard of the relation between gender dysphoria and suicide itself. And it shows that, when you disentangle the effects of psychiatric problems not related to gender dysphoria from the data, there is no difference in the suicide rates of adolescents without gender dysphoria compared to those either presenting for treatment for gender dysphoria or going on to gender reassignment via surgery and hormones. That is, dysphoria and its affirmative treatment doesn’t increase suicidality or suicide itself. You can find this 2024 study below, published last year in the BMJ [British Medical Journal] Mental Health; click on screenshot to read. If you’re blocked, click here to see the full text or here to get the pdf:

The study is the best because it had a large sample, lasted over 23 years into adulthood, and, moreover, was conducted in Finland, where every individual is numbered and their doctor and psychiatric visits tallied. The sample was of 2,083 adolescents who sought gender-identity assessments and/ir desired gender reassignment (GR). For each of these target individuals, EIGHT control individuals were assigned, matched by age and sex. The results were that, without multivariate analysis, there was a slight but nonsignificantly higher rate of suicide among the 2,083 “GR” (gender-referred) children, some of which went on to full transition. But that difference completely disappeared when the authors controlled for other psychiatric issues. As the paper says (my bolding):

Most importantly, when psychiatric treatment needs, sex, birth year and differences in follow-up times were accounted for, the suicide mortality of both those who proceeded and did not proceed to GR did not statistically significantly differ from that of controls. This does not support the claims that GR is necessary in order to prevent suicide. GR has also not been shown to reduce even suicidal ideation, and suicidal ideation is not equal to actual suicide risk. To the best of our knowledge, the impact of GR on suicide mortality among gender-referred adolescents has not been reported in earlier studies. In an earlier study by Dhejne et al,¹¹ even when psychiatric morbidity was controlled for, participants diagnosed as transsexual in adulthood who had undergone both hormonal and surgical GR displayed increased suicide mortality compared with matched population controls. Nonetheless, these authors focused on patients treated before 2002. More recent cohorts, particularly adolescents, may differ from those in earlier decades, and stress related to gender identity itself may be lower presently because of decreasing prejudice.

In other words, gender-dysphoric youth who sought help but did not proceed to gender reassignment did not differ in suicidality from those who went on to gender reassignment. Further, when psychiatric difficulties were taken into account (number of visits to psychiatrists), neither of these differed in either suicidality or suicidal rates from controls. The finding that there was a difference in earlier studies may have been due to the conflating effects of psychiatric difficulties, since those seeking help for gender dysphoria, or proceeding to gender reassignment, apparently have more such difficulties (unconnected to dysphoria) than those who don’t, and psychiatric difficulties greatly increase the rate of suicide.

What all this means is that neither “suicidality” nor suicide itself differs in rate among control children lacking gender dysphoria, whether or not they go on to gender reassignment treatment. The argument for affirmative care that says, “you can have either a dead daughter or a live son” is not borne out, at least by this study. Have a look at it; I was impressed by the quality of the work, which would not be possible in countries where every individual is tracked for both medical and psychiatric care.

The AHA, then, is, to my mind, grossly distorting what we know about suicidality, affirmative care, and the risks of gender dysphoria. It is not known to be safe to give adolescents puberty blockers; there should be a lower age limit; and you are not preventing suicides by giving “affirmative care.” In this sense I consider the article misleading and irresponsible.

So many skeptical/humanist/atheist organizations lose their skepticism when it comes to gender issues! The only one I trust, because it’s published articles on gender like this and this, is the Center for Inquiry, which appears to be the only one that is strongly based on evidence.

But read for yourself, and, if you have time, do a scan of the literature, including the Cass Review.

Tomorrow I’ll publish a letter to the AHA from a disaffected member who took strong issue with the article above, and will say a few words about their response, which I won’t publish as I didn’t ask permission. Thanks to that reader for calling this article to my attention.

Let me finish by saying I have nothing against adolescents or children who feel that they are trapped in the wrong body, nor should there be discrimination (except in sports or things like jails) affecting transgender adults. I’m glad to call anybody whatever pronoun they want, and abhor those who really do dislike or denigrate trans individuals. All I ask for is rationality when it comes to treating young people, and that that treatment should always, like all medical treatment, be based on evidence.

Sex variation in birds, with Emma Hilton’s analysis

August 21, 2025 • 10:20 am

Here we are dealing with sex again. But quite a few readers have written me asking me about the new paper below, which appeared in Biology Letters of the Proceedings of the Royal Society of London. (Click on the title below to read, or find the pdf here.

. . . and there is also a News and Views in Science.

The upshot of the paper is that researchers from Australia looked at 480 Australian birds across five species (rainbow lorikeet, scaly breasted lorikeet, laughing kookaburra, crested pigeon, and Australian magpie); their goal was to see how often a bird’s sex chromosomes (ZW in females, ZZ in males; in birds females are the heterogemetic sex), were discordant with that bird’s gonadal makeup (what we call “biological sex” as well as other aspects of its morphology. (Since these birds are sexually monomorphic for color and pattern, the authors looked at wing, bill, and tarsus size, which presumably do vary among the sexes on average.)

But the main object of study was whether the chromosomes—identified using two sets of DNA primers for genes that were chromosome-specific—were dicordant with the gonads. If everything’s concordant, all ZW birds should have ovaries and all ZZ birds should have had testes.

The surprising result was that there was a fair amount of discordance between sex traits (gonads) and the chromosomes, ranging between 3% and 6% of individuals depending on the species. (These individuals are called “sex reversed”, which I think is a bit confusing.) But it’s still high. Moreover, most, but not all of those “sex-reversed” (henceforth “SR”) individuals seemed to have gonads that appeared normal, though testes in SR ZZ males were generally smaller than normal. We don’t know what percentage of the SR birds were fertile, though at least one female showed signs that she produced an egg.

The authors also found that more than a third of the SR individuals had both male and female gonadal tissue, though most of these were all likely sterile or fertile as only one sex (the authors dissected dead or injured birds sent to wildlife hospitals and thus don’t know their reproductive history). From the paper:

. . . . . 20% of sex-discordant individuals in our study presented with some gonadal enlargement, indicative of reproductive readiness [67–69], while 36% had atypical gonadal make-up (i.e. ovotestes, both an ovary and a testis or ambiguous gonads.

My conclusion:

Since I’ll take 5% as the general proportion of SR birds, 36% of that is about 1.8%, meaning that 1.8% of the sample—if you consider these birds a random sample—had a mismatch between gonads and chromosomes, either having fairly normal gonads that were different from those predicted by the chromosomes, or having ovotestes and were true intersexes. That is unexpectedly high. The authors do say that birds can get screwed up this way because they’re susceptible to environmental toxins, but we don’t know about these individuals.

Now before these data are scarfed up and distorted by gender activists, I have to make a few points:

1.) Humans do not have anything like this kind of discordance. How do we know? Because by now thousands of human genomes have been sequenced, both randomly by the NIH and the “thousand genome project” (now much more than 1000), as well as gene-sequencing companies like 23andMe, and if there were this kind of discordance, we would know: fertile women who submitted their DNA, for example, would hear that they had a Y chromosome. So you can’t extrapolate these bird data to humans, who are very different in both chromosomal constitution and lability to disorders of sex determination (see Emma Hilton’s tweets below).

2.) The prevalence of “intersex” individuals in humans is much lower than these authors observed in birds. Although “intersex” has been estimated in different ways by different people, decent estimates range around one in 5,600 people (0.018%) or, close to that, about 1 individual in 6700 (0.015%). That is much lower than 1.8%, which is nearly 2 birds in a hundred. Extrapolations to humans are again unwarranted.

3.) These data do not tell us that the sex binary is wrong, in birds or any other animal. Even the SR birds, produced either testes, ovaries, or tissues from both: two types of reproductive tissue evolved to produce the two types of gametes that constitute the sex binary. There was no tissue that could have produced any other type of gamete, nor do we know of any such thing in birds.

4.) These data say nothing about the prevalence of gender-nonconforming or transsexual individuals in other species, including humans. It is folly, of course, to use this kind of data from nature to address these gender-ish phenomena in humans. What these authors have an “is” (discordance) in birds, but gender-nonconforming and transsexual people in humans still conform to the sex binary, but feel their gender is different from that of their natal sex. And of course discussing the problems with extrapolating these data to humans is not in any way “transphobic.”

So that’s my caveat, but Emma Hilton from the University of Manchester, who knows a lot more than I do, has produced a thread of tweets about the paper with her usual wit. The tweet thread starts here, and I’ve posted them all below.

Emma’s last couple of tweets were added in response to my importuning her to say something that I could understand, because, with her knowledge, she wrote tweets I found hard to fathom. She also wrote me an email in response to my own question, which as I recall was something like, “Emma, does this mean that the proportion of true intersex birds is much higher than found in humans?” Her response [“DSD” means either “disorders of sex determination” or its more euphemistic “differences of sex determination”].

I’m not resistant to “true intersex”, although I could introduce a resolution not often talked about – the left-right resolution 😀 [JAC: see below about developmental asymmetry]

OT-DSD (ovotestis-DSD) in humans is “true intersex”, at least when the amounts of each tissue generate meaningful conflict in downstream development, which, for the most part, they don’t. Most OT-DSD is discovered in XX individuals with residual testicular tissue that doesn’t interfere with healthy ovarian tissue function and downstream development i.e., they are uncomplicated females and furthermore, natural mothers!

(On the above, there is brilliantly-crazy paper that you might like to see, where a group of medics in Turkey – IIRC – present a panel of female OT-DSD and babies [all good info], and the whole discussion is about Jesus and the possibility of virgin births).

So birds are more plastic than humans for various reasons – the specifics of their genetic determination, the common asymmetry of development in females (that might hint at the possibility of sequential hermaphroditism), the ensuing susceptibility of the undifferentiated gonad to a “make male” trigger.

So I’d be happy to stand by the premise that OT-DSD is often “genuinely intersex” at the individual level (typically arising from a left-right conflict) and the birds are more susceptible to this particular type of conflict.

h/t: Luana

Scientific American reverts to unscientific wokeness

August 20, 2025 • 10:00 am

Well, Laura Helmuth may no longer be at the helm of Scientific American, but the magazine seems to have again again dipped its toes into the waters of unscientific ideology. To wit: they’re posted a 14-minute podcast emphasizing that nature—and that includes humans—is “non-binary”. The problem is that, as usual, they get what is binary (biological sex) deeply confused, conflating it with behavior and morphology of animals, features that, while they may be bimodal, are not nearly as nonbinary as biological sex, which, as I’ve explained ad nauseum, defined on the basis of gamete types. (See also this post by Richard Dawkins.)

If you click on the link below at Scti.Am, you can hear this ideologically-motivated discussion between writer Rachel Feldman and biologist Nathan Lents of John Jay College, who is touting his new book (see bottom). I haven’t read it, but he summarizes its thesis in the podcast. The ideology is implicit, not explicit, but is encapsulated in the constant and obsessive denigration of the binary by both Feldman and Lents. The problem is that they don’t understand what biologists mean by “the binary.” It’s the binary of gamete type (used to define biological sex), Jake!

Click to listen. It’s only 14 minutes, but I found it painful.

The mishigas begins at the beginning, when Feldman, touting the “nonbinary” thesis, proclaims at the start

“What we’ve often labeled as anomalies might actually represent successful evolutionary adaptations deserve serious study. And these creatures can help us understand how our own species breaks the binary, too.”

But of course nobody with any brains has ever said that the diversity of behaviors in human males and females, or the fact that there is some overlap in traits like height red blood cell count, ARE binary. We recognize that traits like height are bimodal (the modes certainly reflect some sexual selection), but Feldman, like Lents, misses the real binarythat’s at issue (and that has led to sexual selection): the binary of gamete type. For reasons Richard Dawkins, Emma Hilton, Colin Wright, Carole Hooven, and I have explained at length, gamete type is the concept of sex (not an a priori definition), because a binary of gamete type (large, immobile eggs vs. mobile sperm) is almost completely universal in plants and animals.

Nor has anybody with neurons that work said that the diversity of behavior, morphology, and so on in mammals is unworthy of study, or doesn’t exist. Look at all the attention devoted to the difference between bonobos and chimps, for example!

At any rate, Feldman says that Lents’s new book claims that biologists have completely failed to appreciate the role of diversity among individuals in the life of social animals. As she says, Lents’s book “breaks down the idea of there being a sex binary in most places in the natural world.”

This is confused. There is a binary of gamete type—eggs and sperm—in all animals and plants. While some creatures like earthworms can be hermaphrodites, they still carry only eggs and sperm, and thus are members of both sexes, not a third sex. There is no third type of gamete.

But of course if you take any other trait, there is variation within sexes. Even in humans there is variation within males in whether or not they have a penis, and this rare variation does not represent a third sex, or a breaking of the binary of sex, but a developmental anomaly. Nor does the variation among very rare “intersex” individuals represent a “successful evolutionary adaptation”, for most of these individuals in humans are sterile.

Now some variation in behavior can be an adaptation, for example the existence in some fish species of what is called “sneaky fuckers“: males that develop the appearance and behavior of females so they can get close to females to mate with them without attracting the attention of aggressive larger males. But these s.f.s are still males. There is a nonbinary of reproductive behavior, but not of sex. The sneaky fuckers are MALES. It is annoying that neither the interviewer nor Lents realize that this behavior not breaking the binary of biological sex, but affirming it. What is broken is uniformity of sexual behavior, but nobody every claimed it was unbreakable.

In fact, Lents pronounces here that “The binary is really the problem. . . instead what you see is a continuum. . of masculinity and femininity”. . . . The categories [of male or female] themselves are too narrow to be helpful. . . Natural variation doesn’t fit into those buckets.” I cannot believe that Lents is unaware that the controversy about sex has involved the binary of biological sex, and that this controversy exists for only one reason: some humans don’t accept their natal sex. Every biologist who has followed this ideologically-based disputation knows that. Instead, Lents asserts that “The binary is inhibiting us,” and implies that those who reject the binary are not “open minded”.

That is wrong and misguided. I propose that Lents wrote this book for the same reason Agustín Fuentes probably wrote his book: if you reject the male/female binary, it supposedly supports the worldview of those people who don’t think of themselves as male or female, or feel that they are really members of the sex that wasn’t their natal sex. This feeds into the “progressive” view exemplified by the mantra “trans females are females” (or the same for trans males).

This ideological rejection of the sex binary exemplifies what Luana Maroja and I called “the reverse appeal to nature”: imposing your ideological views of what’s good onto nature itself. (It’s the converse of “the naturalistic fallacy”). But recognizing that biological sex is binary in humans, all other animals, and plants is not constricting or inhibiting. Au contraire: it’s opened up whole new worlds of investigation, including theoretical investigations of why the sexes are always two (cf. Ronald Fisher) and, most of all, the recognition that sexual selection and sexual dimorphism is nearly always explained at bottom by differential investment of males and females in their different gametes. Ignoring the sex binary in this case would lead to our missing crucial understanding of traits that are ubiquitous in biology (e.g., ornamented and plumed males versus more drab females, males competing for females, etc., etc., etc.).

I’ll add one more evasion that Lents makes. He cites Joan Roughgarden’s book Evolution’s Rainbow as support for his views, but doesn’t note that Roughgarden herself, who is trans, nevertheless said explicitly that biological sex is binary. What Roughgarden got wrong was repeatedly committing the naturalistic fallacy: arguing that the diversity of sexual behavior is animals somehow justified the diversity of sexual behavior in humans. That was unnecessary, and a logical fallacy. Showing that female bonobos rub their vaginas together does not prove that lesbians in human are “natural” and not immoral. That has no bearing on the issue. The morality of same-sex behavior in humans doesn’t need justification by finding it in animals. Even if no animal showed it, there’s would still be nothing wrong with homosexuality. (I reviewed Roughgarden’s book in the Times Literary Supplement, and will be glad to send readers a full copy if they inquire, as it’s no longer on the Internet.)

But I digress, and will make only one more point. When Lents is asked to give a “nonbinary” example of behavior, he cites recent work showing changes in the behavior of Hawaiian crickets. A fly that parasitizes these crickets invaded the islands, attacking the males who chirp loudly to attract females. Chirping thus became maladaptive, and natural selection silenced males, so they had to attract females without chirping. Lo and behold, many (though not all) of the cricket males became silent. But they still got mates. Why? Because the silent males paired up with calling males, so they could still get females without calling attention from the parasitic flies. This pairing was adaptive for the silent males, though probably not for their chirping confrères.

This is interesting, and probably an example of evolved behavioral change in one sex—but note that Lents still refers to two sexes as “male” and “female”, implicitly accepting the sex binary. For crying out loud, no biologist doubts that there can be behavioral “polymorphism” in animals. In bees, females can be sterile workers and, less often in a colony, fertile queens. That is not a problem, nor does it even bear on the sex binary.

As I said, Lents surely knows that the binary at issue is one of sex definition, not sexual behavior or morphology. He doesn’t mention the binary of biological sex. Instead, he caters to “progressive” listeners by repeatedly assuring them that the binary (whatever it is) is dead.

It’s dead, but it isn’t lying down, and never will. To talk about the sex binary as Lents and the reviewer do, is, I believe, intellectually dishonest. (It may be in the book, but I’ll bet that if it is it will be denigrated as irrelevant and distracting).

I hoped that the new Scientific American, sans editor Laura Helmuth, wasn’t going the Helmuthian route of distorting biology to cater to the au courant liberal ideology. I’ll be watching them. In the meantime, sex is binary: there are two sexes, and that’s all she wrote.

Evolution meetings include an ideologically-based symposium on “teaching sex and gender”. It’s a spectrum, Jake!

June 20, 2025 • 11:00 am

A while back, the Presidents of the Society for the Study of Evolution (SSE), the American Society of Naturalists (ASN) and the Society of Systematic Biologists (SSB) posted this letter on the SSE website (click title to see archived version):

The letter was a response to Trump’s Executive order on sex, which gave the biological definition of sex: a binary based on the physiological apparatus for producing gametes of different size, of which there are two forms. This is how the “Tri-Societies Letter” (henceforth “TSL”) started:

As scientists, we write to express our concerns about the Executive Order “Defending Women From Gender Ideology Extremism And Restoring Biological Truth To The Federal Government”. That Order states first, that “there are two sexes…[which] are not changeable”. The Order goes on to state that sex is determined at conception and is based on the size of the gamete that the resulting individual will produce. These statements are contradicted by extensive scientific evidence.

The TSL, posted on the SSE webpage, asserts that sex is a multivariate trait, is not binary but a spectrum, and that this spectrum occurs in all biological species. It adds this (bolding is mine):

Scientific consensus defines sex in humans as a biological construct that relies on a combination of chromosomes, hormonal balances, and the resulting expression of gonads, external genitalia and secondary sex characteristics. There is variation in all these biological attributes that make up sex. Accordingly, sex (and gendered expression) is not a binary trait. While some aspects of sex are bimodal, variation along the continuum of male to female is well documented in humans through hundreds of scientific articles. Such variation is observed at both the genetic level and at the individual level (including hormone levels, secondary sexual characteristics, as well as genital morphology). Beyond the incorrect claim that science backs up a simple binary definition of sex, the lived experience of people clearly demonstrates that the genetic composition at conception does not define one’s identity. Rather, sex and gender result from the interplay of genetics and environment. Such diversity is a hallmark of biological species, including humans.

Note that it gives no way to determine whether an organism, including a human, is male or female! And how many sexes are there? This gives us no clue.

The letter went on to imply that all the members of the society, or at least nearly all of them, agreed with the Presidents’ views in the TSL:

Our three scientific societies represent over 3500 scientists, many of whom are experts on the variability that is found in sexual expression throughout the plant and animal kingdoms. More information explaining why sex lies along a continuum can be found here. If you wish to speak to one of our scientists, please contact any of the societies listed below.

It turned out that this was a distortion: the Societies had never polled their membership to see how many people agreed with their letter.

The result was considerable pushback against the TSL from scientists, 125 of whom wrote a letter to the Societies saying they didn’t agree with the TSL’s characterization of sex. Luana Maroja was the driving force behind this pushback, and the letter included this (I signed it, of course):

However, we do not see sex as a “construct” and we do not see other mentioned human-specific characteristics, such as “lived experiences” or “[phenotypic] variation along the continuum of male to female”, as having anything to do with the biological definition of sex. While we humans might be unique in having gender identities and certain types of sexual dimorphism, sex applies to us just as it applies to dragonflies, butterflies, or fish – there is no human exceptionalism. Yes, there are developmental pathologies that cause sterility and there are variations in phenotypic traits related to sexual dimorphism. However, the existence of this variation does not make sex any less binary or more complex, because what defines sex is not a combination of chromosomes or hormonal balances or external genitalia and secondary sex characteristics. The universal biological definition of sex is gamete size.

You can see my other posts about this kerfuffle here.

The response from the Societies can’t be posted as we were refused permission to do so, but I characterized it this way:

. . . . this time we asked for a response and got one, signed by all three Presidents. I can’t reprint it because we didn’t ask for permission [we later did but were refused], but some of its gist is in the response below from Luana [Maroja]. I will say that they admitted that they think they’re in close agreement with us (I am not so sure!), that their letter wasn’t properly phrased, that some of our differences come from different semantic interpretations of words like “binary” and “continuum”(nope), and that they didn’t send the letter anyway because a federal judge changed the Executive Order on sex (this didn’t affect our criticisms). At any rate, the tri-societies letter is on hold because the organizations are now concerned with more serious threats from the Trump Administration, like science funding.

The upshot was that the Societies eventually decided to remove the letter from the SSE website. What remains on the the original page is this, “This letter was originally posted on February 5th. A revised version is in progress and will be posted shortly.”

We are still waiting. I’m betting that no revision will ever appear. And it shouldn’t, for it’s not good for the premier evolution societies to pretend that biologists see sex as a spectrum.

What I’m leading up to is that, at the SSE’s annual conference taking place this month, the Society is sponsoring a three-hour symposium with four lecturers, a symposium that seems designed to reiterate the premises of the now-vanished letter. You can see the summary of this symposium by clicking on the link below to see synopses of the four lectures; then click on the bottom symposium, which looks like this:

If you go through the written summaries of the talks, you will see two themes reiterated:

1.) Biological sex is not binary but multifaceted, a “complex suite of traits across multiple organizational levels”. No definition of biological sex appears to be given.

2.) Teaching that sex is binary harms those people who feel they’re not part of the binary, presumably nonbinary people, genderfluid people, some trans people, and the like. An important goal of teaching about sex and gender is to avoid harming people, and this form of teaching must be designed to avoid that harm.

The first point simply reiterates what was in the now-disappeared letter. It makes the argument that many “progressive” biologists make: sex involves a combination of different traits. This of course neglects the universality of the gametic definition, for no other definition holds for all animals and vascular plants. That’s why the definition (really a post facto observation) is used. In fact, many of those who hold to the “multifactoral” definition never even give a definition of sex, so I don’t know how they can tell that, say, a rabbit is male or female.

The second point turns biology teaching into a form of social engineering or propaganda: we must teach about sex in a way that does not harm people (i.e., offend them). I see this as distortion of biological truth in the interests of social justice, something that Luana and I discussed in our paper “The Ideological Subversion of Biology.” In fact, of course, teaching that biological sex is binary should not make anybody feel worthless or demeaned, for the dignity and rights of people depend not on biology but on morality, which is a social construct. I have made this point endlessly and won’t repeat it here; see the end of the paper linked just above.

Some quotes from the summary and the abstracts:

Symposium summary at the beginning:

This symposium will explore the current science behind sex and gender, explore how educators can move their instruction beyond simple binary XX/XY paradigms, and provide educational materials for teaching this nuanced and difficult subject.

The non-binary nature of sex:

However, “biological sex” can describe a complex suite of traits across multiple organizational levels, including chromosomal inheritance, physiology, morphology, behavior, etc. To capture the full range of sex variability and diversity, we must critically assess our research approaches for studying sex associated traits. In this talk, I will provide practical guidance for conceptual frameworks, experimental designs, and analytical methods for studying and teaching the biology of sex. I invite fellow scientists and educators to conscientiously apply these inclusive approaches, to advance our biological understanding of sex and to encourage academically and socially responsible outcomes of our research.

. . . . Biology is the study of the diversity of life, which includes diversity in sex, gender, sexual behavior, and sexual and romantic orientations. However, the few existing studies of biology textbooks and classrooms suggest that many textbook authors and classroom instructors represent only a narrow swath of this diversity which can lead to an over emphasis on binary sex, conflation of sex and gender, and reinforcement of essentialisms.

Biological sex is a complex and highly variable trait; however, overly simplistic explanations are common in undergraduate biology classrooms. Here we test the impact of an accurate approach to teaching about the diversity of biological sex in organismal biology (‘treatment’ lecture) and compare this approach to a ‘traditional’ lecture section of the same introductory biology course.

The harm of teaching sex “wrongly”.

Although science is thought to be objective and free of emotion, many people are uncomfortable talking about the biology of sex. That discomfort and fear leaves room for hostile attacks on the science of sex to easily propagate through political and social channels. This creates unique challenges for educators in this area. In this presentation, I will discuss the biological basis of sex and sexual diversity from the perspective of a developmental biologist. The hierarchical nature of development connects genetics to phenotypes. Development dictates how sexual diversity emerges within species. The evolution of development dictates how sexual diversity arises among species. I will use development to demonstrate how biologists can distill complexity down into understandable chunks to address the most pervasive misconceptions about sex, especially those actively being used to take away
people’s rights.

. . . To more fully characterize the current range of narratives about sex, gender, sexual behavior, and orientation (SGBO narratives) present in undergraduate biology courses, we interviewed a national sample of 53 biology majors whose genders do not align with the sex they were assigned at birth (i.e., trans-spectrum students) about the SGBO narratives they encountered in biology courses.

We analyzed interviews using reflexive thematic analysis with the goal of identifying SGBO narrative in biology content and how these narratives supported or harmed these students’ sense of belonging in biology classrooms. We found five SGBO narratives that harmed trans-spectrum students’ sense of belonging. We also found three narratives that supported trans-spectrum students’ belonging. These narratives could manifest in the classroom in multiple ways ranging from short disclaimers to elaborate case studies. The ways the narratives manifested influenced their impact on at least some students. These narratives and how they manifest provide potential teaching suggestions to both support trans-spectrum in STEM classrooms and more accurately teach the diversity of biology of sex, gender, sexual behavior, and orientation.

(Continuing the last quote in the section just above):

. . . We show that (1) the treatment lecture has a positive impact on feelings of inclusion for LGBTQIA+ students, (2) the treatment lecture had a positive impact on LGBTQIA+ and TGNC (transgender and gender nonconforming) student experiences in the course compared to other students. . .

This is not a huge deal, but I don’t think that one should distort the most widely accepted definition of sex to avoid offending people who don’t think they adhere to it. I can’t see any other reason for this symposium. And yes, sex is binary, and that’s universal: there are only two types of gametes, and this holds across all animals and vascular plants. It’s not only universal but useful, for the binary enables us to understand one of the most important phenomena in biology: sexual selection, a form of selection that leads to differences between males and females. Of course teachers should be sensitive to their audience and not denigrate those who feel non-binary, but they should also teach the conventional wisdom about sex, which is apparently not going to happen at this symposium.

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