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.

69 thoughts on “Short (?) review: “Sex is a spectrum”

  1. There’s an indelible idea I first heard Dawkins say in one of his earlier speaking tours:

    Willful misunderstanding

    Fuentes has the same thing going on here – I mean I think that’s the only way to come up with it – to know exactly how sex works. How else? It’s not random words strung together, right?

  2. Fuentes is giving us a masterclass in motivated reasoning. He is explicit that the intent of his book is to further various forms of gender politics – such as allowing women’s rights and protections to men with “trans identities”. And so he starts with his conclusions that sex is an ill-defined, fluid and rather constructed concept, and works backwards from there.

    His difficulty is that he knows enough biology to make this hard for himself. So, he has to resort to omission and logical contortion to get to his conclusion.

    1. Even if sex were “just a social construct,” as Fuentes seems to think, so what? What makes anybody think that socially constructing a sexless/genderless society would be any better? Why do they think such a society wouldn’t have worse outcomes than has the battle of the sexes?

  3. There is nothing “intersex” about individuals with disorders of sexual development. The term is misleading to its core.

    You can’t be “inter-” a binary, and they aren’t. There is no intermediate gamete.

    “Intersex” is a misnomer. There are only males and females with disorders of sexual development.

    1. Indeed. People with such “intersex” conditions are not exceptions to there being just two sexes. They present challenges in classification at best. The number of classes still remains at exactly two: male and female So, at worst the challenge of such medical conditions is whether or not there are individuals where we can say they cannot be classified as male or female. I do not think that is true for anyone or any condition.

    2. I agree that it is an unsatisfactory term and it isn’t literally used for a person who is ‘between sexes’ as there’s no such thing, but people with those conditions use the term themselves in their organisations, so I think we are stuck with it until they use a different name.

      I’d really like them to change the term to make it clear that they aren’t part of the gender woo mob.

      1. The term “intersex” is mostly hated by people who have disorders (or differences, sometimes referred to as variations) of sexual development (DSDs/VSDs). They have repeatedly requested LGBTQIAP+ (or whatever) campaign groups not to use intersex or include them under the ever-expanding “trans umbrella”, but to no avail. It seems that their medical conditions are too useful to those trying to blur the dividing line between the sexes or even to deny that it exists at all.

        1. Yes, the alphabeti spaghetti are appropriating medical conditions that are nothing to do with trans.

          A person with a DSD/VSD does not necessarily have an intersex condition. I shared this interesting. link on a comment here that explains it….

          https://www.realityslaststand.com/p/intersex-is-not-as-common-as-red

          If the term was mostly hated then their organisations and campaign groups wouldn’t use the term in their names, eg the International Intersex Forum (IIF). But I hope they DO change it, as it is often misunderstood, and doesn’t belong with LGBT, but they need to be the ones to do it.

          Yes, the IIF has asked not to be included in the alphabet soup, but arrogant transactivists think they know better and refuse to let them go.

          Earlier this year the genderwoos produced yet another flag with yet another symbol, and claimed the flag now includes people with disabilities. There were so many complaints and they seem to have dropped it.

          Soon, all the additions will have erased the original rainbow flag.

  4. female/male applies to millions of species. woman/man are simply human instances of female/male. fuentes must show how his ‘sex is a rainbow spectrum of genderly feelze’ applies to all of these millions of species or his thesis fails.

  5. Bogardus‘s review was excellent. It will be difficult for Fuentes to counter. Thank you for persevering through Fuentes’s book and for keeping us apprised. You have the patience of a saint.

  6. One could play more games with frequency of more this or less that at birth, and the #%^$ Google AI once again is too helpful and so here I am being lazy about looking stuff up. According to the #%^$ AI …
    The frequency of people born with only 1 kidney is ~ 1/1000 (!). Birth with extra kidneys also happens, but is very very rare. But there is no kidney spectrum on the radar.

    The frequency of people born with 1 or more limbs missing rounds out to ~ 1/2000 births. Extra limbs are very rare, ~ 1/1000,000 births.

    And these are real biological things, not imagined biology because of how one feels.

    1. I agree. Any human organ could have been malformed during embryonal and prenatal development. That does not mean that each organ exists as a spectrum or on a spectrum. No, it’s normal versus malformed. If you are born with fewer or more than 10 fingers that’s abnormal.

    2. Surely scholars of Critical Limb Theory have argued for the spectrum of limb and finger number; and gone on to explain how the “normality” of two arms and five fingers is a social construct, devised by the evil Europeans in their colonial system of oppression.

      Frankly, I am puzzled by the absence of one crucial and extremely obvious aspect, downstream of the gametic definition, in most discussions of “gender”: viviparous development. In species like ours, the next generation is born alive after development in the womb of one and not the other sex. Have Augustin Fuentes and colleagues attempted to find spectrum aspects of this phenomenon?

      1. Jon, you joke about it, but “Critical Renal Theory” is a thing.

        “Hemodialysis Disparities in African Americans: The Deeply Integrated Concept of Race in the Social Fabric of our Society”
        doi: 10.1111/sdi.12589

        “Inflammation and the Paradox of Racial Differences in Dialysis Survival”
        doi: 10.1681/ASN.2011030305

        “Racism and Kidney Health: Turning Equity Into a Reality”
        doi: 10.1053/j.ajkd.2021.01.010

        “Racism versus precision in defining glomerular filtration rate?”
        doi: 10.1093/ndt/gfae015

  7. I have developed a HUGE annoyance with the word “spectrum”. Somebody is not just a little bit autistic or very autistic, but is “on the spectrum”. Instead of trying to argue that biological sex has interesting features other than the purely gametic, we are told “sex is a spectrum.

    These days I rather loathe the word “spectrum” except in the context of optical frequencies or eigenvalues of bounded self adjoint operations acting on Hilbert spaces or objects of the stable homotopy category that represent generalized cohomology theories.

      1. Maybe so. I must add, however, that the usage of “autistic spectrum” has some value in categorizing certain kinds of moderate or borderline cognitive disabilities— and in qualifying such cases for special educational and other services.

  8. Jerry wrote (bolding added by me):

    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.).

    I used to think (around the time of the North Carolina bathroom controversy in 2016) that sex segregation of bathrooms was not necessary. But I have changed my mind on that. I now oppose trans-identified males using women’s bathrooms for safety reasons. Under sex self-ID any male can claim at any time that he feels to be/is a women. With sex-desegregated bathrooms, predatory males can access women’s bathrooms, and such a male could say to a concerned woman in the bathroom that a (biological) man in the bathroom is nothing unusual or suspicious, no need to let your guard down. Sex-desegregation (coupled with sex self-ID) would normalize a dangerous situation (a male in a women’s bathroom).

    If it were an issue of whether castrated males should be allowed to use the women’s bathroom, I could agree to this.

    I would be interested in why Jerry thinks that “we should not have bathrooms based on natal sex.”

    1. Safety is one concern; modesty is another. Taken as a whole, a man is more likely to go into the Woman’s bathroom to leer and smirk than cause violence (though that statistical distinction may be blurred if the women strenuously object to being ogled.)

      A trans-identified male who enters the Woman’s is probably more likely to quietly go about their business than peep. I think that’s only significant, though, if TIMs feelings of satisfaction and belonging outweigh any “inconvenience” to women.

      1. I favor bathrooms that accommodate one person at a time: we have five of these in my building. When you design for more people, it becomes more problematic, as Helen Joyce describes in her book “Trans”, where she makes a good case for single-sex bathrooms designed to hold more than one person.

        1. A school here bragged about having bathrooms with floor to ceiling walls with no space for cameras under the door and with dead bolts. They claimed they were safe for girls..

          I asked how long it would take a teacher to get through the dead bolt if a boy had dragged a girl into the toilet to assault her. They didn’t reply.

          In several schools boys find it ‘funny’ to break the locks in unisex bathrooms so they can walk in on girls. In many places, girls now only use the bathroom in twos.

          “bathrooms that accommodate one person at a time” are reasonable if they have sinks, driers and sanitary bins, but they take up a lot of space. If my gym was to install them, we would lose at least one of the studios.

          Separate loos has worked for 100 years. I don’t see any need to change that to accommodate a tiny percent of men.

      2. “A trans-identified male who enters the Woman’s is probably more likely to quietly go about their business than peep”.

        There is no way to tell which men in dresses have gender dysphoria and which are predatory paedos like ‘Katie’ Dolotowski, ‘Jessica’ Yaniv and the WiSpa perv. That’s why ALL males need to stay out.

        Spend a few days on X and you will see hundreds of men in dresses, sharing photographs of themselves, bragging about being in the women’s spaces and saying how exciting is to listen to women peeing or unwrapping their sanitary products in the next cubicle. Some do a lot worse.
        Involving sanitary bins, but I won’t go there.

        I know many decent transwomen who use the gents with no issue. They all should.

          1. It definitely is! But it is handy to keep some of those images to use against them when they say that women are not endangered by men in their spaces. Their own fetishes are plain to see and, gradually, people are seeing them.

        1. Just a data point: what you see on X depends a lot on who you “follow”. I’ve spent time on X and don’t see posts by that sort of man (let alone ‘’hundreds” of them). I have occasionally seen posts of screenshots of that sort of thing, posted by gender-critical women.

          1. Of course, it depends on algorithms. I don’t follow any predators, but I follow a lot of gender critical people and we point each other to men who are abusing our spaces so that we can gather the data to show the ‘be kind’ people how some men are abusing our spaces.

            A lot of people don’t see what’s going on, so they deny it happens. When they share stuff like ‘transwomen are safe in women’s spaces’, GCs share news articles about the paedophile ‘Katie’ Dolotowski who sexually assaulted little girls in women’s toilets, or ‘Amy’ Miller who kidnapped a girl and sexually abused her for two days before she escaped, or we share photographs of men masturbating in women’s toilets. I always censor those pictures, but without them naive people can deny what is happening in the real world.

            ‘Hundreds’ is probably a huge underestimate. I’m only referring to what I have seen. You can find several cesspits on Reddit where those people gather and you can see the numbers, and their deeds, for yourself. Or look at government statistics. UK ONS stats show that over a seven year period 436 men who self identified as women were prosecuted for rape.

            Perhaps you don’t see these posts because you don’t get involved much in supporting women and girls.

            This is not all transwomen, there are a LOT of decent ones. I follow many. They use their own male spaces. But those who cross women’s boundaries are predators and need to be kept out of women’s spaces.

    2. I wrote too quickly and my opinion needs nuance, which I’ve put below. I favor bathrooms that accommodate one person at a time, where there’s no pborlem. At places like ballparks or where you expect several occupants, then yes, there is a problem which I’m working around in my head.

      1. Then let’s envision places where there might be either many or few occupants depending on time of day. Take an interstate rest stop well after dark. A mother arrives with her two young daughters. There is one other car in her parking lot, but dozens of semi-trucks idle on the other side of the building. Should she use the restroom or not? If you normalize the practice of male bodies in female spaces, then you will desensitize male protectiveness. You might, perhaps, in some jurisdictions find forms of it made illegal. Currently, if a man were to follow that woman or one of her children into the restroom, then any number of truck drivers who saw it would come to her aid—at least they would in my part of the country. Would you like them to set aside their vigilance? Should they become apathetic in the face of social pressure or threat of lawsuit?

        And setting aside safety, perhaps many women are simply uncomfortable tending to female concerns in the presence of men. Should we tell them to just get over it? Just shut up and change the tampon? Strip your body in front of that penised person and get on with your shower? And yet, here we are as a society, cowing to the strident demands of a tiny minority of men, telling women to bear the burden. Why? Is it so we can feel liberal and tolerant in the face of a never-ending activism that has no use for liberalism and its presumed tolerance?

        I wish you luck as you wrestle through this issue. We might point to countries that do things differently than we, but I would step cautiously in trying to pick-and-choose social practices that are embedded in a deeper cultural web. I long ago staked my position, the concerns of even a minority of young women and girls vastly outweigh for me the competing position of a significantly smaller number of men (and their female allies) who advance dubious claims. The incessant badgering and bullying by unreasonable people have also had another effect: I have reached the “F@ck them” stage of development. It is weirdly liberating—and no less concerning for being so.

        1. You really understand the situation Doug, thank you.

          Men who respect women have no issue staying out of our spaces. The only men who would cross women’s boundaries are, by definition, predators. 1 in 4 women has been raped or sexually assaulted by a man, many of us suffer from PTSD as a result. I took a full blown panic attack when I saw a male face under the door while I was taking a shower at my gym. It threw me back to an incident from my past and I couldn’t breathe. Why should women have to avoid using our own spaces because men might be in there?

          A friend had to leave a cubicle door open to help her elderly mother. A woman with toddlers and shopping bags may need to leave the door open. Women understand these things, and it doesn’t bother us, but it’s undignified to do this in front of men.

          1. “I took a full blown panic attack when I saw a male face under the door while I was taking a shower at my gym.”

            How do you know that it was not a female-to-male trans person, just using the facility consistent with their birth sex? One of my colleagues is female-to-male trans, is bearded, hefty in a very male way, and would seem to be completely out of place in the ladies’ room….. Yet that is what Trump is pushing for.

          2. #Barbara Piper

            It wasn’t a female. I took the panic attack before I even realized that it was a young male. My therapist explained that there is a primeval part of our brain that can recognise signs of danger by instinct and trigger us, before we even realize it in our conscious brain.

            Plus females commit only 0.05% of sexual assaults so it is highly unlikely that a female, even a trans identified one, would do such a thing, or be a danger to other women.

          3. @Joolz — My apologies for not making the point more clearly. The hypothetical was in the service of a warning to everyone: be careful about what you wish for.

      2. “What term do those having disorders or differences of sex development prefer be used? Let me know what the consensus is and I will use it.”

        The post above doesn’t have a reply button on it so I’ll respond here.

        People in the USA seem to use VSD and UK DSD, but I was reprimanded for using the term DSD
        by a woman who insisted she is intersex and active in that community.

        There are many organizations that use the term intersex, eg OII Europe (Organisation Intersex International Europe) and I have been told to use DSD/VSD for things like Klinefelters and Swyers, as per the link I shared from Colin Wright.

        Perhaps we could ask them to discuss it at their upcoming conference and give us a definitive answer. I agree that we should use whatever term they want when discussing those conditions.

        https://www.oiieurope.org/community-event-and-public-conference-2025/

      3. Pray, what is wrong with going with women’s preference on this, which is to require that people must use the bathroom of their sex? Period. Trans-identification simply doesn’t confer any rights on one to cross boundaries created for women’s privacy and security of the person, or any new rights of any kind at all. One doesn’t get to do anything, or demand that any special accommodation be made for one just because one calls oneself transgendered. I am loath to level the accusation that you are overthinking this, because most problems benefit from more thinking, not less. But here I am tempted. How is the moral arc of history bent toward justice by letting men use women’s bathrooms just because they want to?

        Architects have been designing public bathrooms that have to serve members of the general public for a long time. Men’s rooms with mostly urinals and a few toilet stalls, and women’s rooms with all stalls (and more stalls than the men’s room has) have stood the test of time in best use of floor space. “Queering” the plumbing at great expense just doesn’t seem to have any rationale other than perversity.

        1. 🎯 Thank you. If it ain’t broke there’s no need to fix it.

          Add more single use spaces if you want, we could do with more spaces for the disabled, but don’t change those safe spaces that we already have.

          1. And I’ll just press a bit by saying don’t build more single spaces. Someone has to pay to build them but more important they come out of the space budget. Somebody else has to give up something in order to find space for them. If only so many square feet of floor space are budgeted for public bathrooms (which don’t pay rent), building single-occupancy spaces means fewer users in aggregate can be handled from the same budget. We lose urinals, essentially, and many more sinks have to be installed, one per toilet.

            Fewer urinals stiffens male resistance against enlarging women’s bathrooms to equalize queuing time. We’ll say, “Ladies, you should have thought of that when you endorsed single spaces for trans people to use. We gave up our urinals to turn the floor space into single spaces so you would no longer be harassed by trans-identified men seeking ‘refuge’ in your space. There goes any co-operation from us to reduce our space even further to build larger female-only multi-use space, which would benefit you more in the long run.”

            There may be a case for enclosed single-occupancy bathrooms in areas where they sit empty most of the day. One toilet is then cheaper than one that can handle five or ten people at a time but rarely does. Then they could be unisex but in practice they usually aren’t, just because, I suppose, the building management wants the men to use easier-to-clean urinals as much as possible.

            Finally, single-occupancy spaces can be surreptitiously colonized by homeless people, denying them to everyone else until they are eventually rousted, or found dead of overdose. This requires that legitimate users have to get permission from some authority to have them unlocked, rather than just entering as needed.

  9. Had a brainstorm about “spectrum”.

    Some physics/math terms came to mind :

    •quantized
    •discrete

    … I think a case might be made somehow that sex – like the brilliant notion of digits – or legs – is discrete, or sorted into certain levels.

    That is in contrast to e.g. sound volume (amplitude) or energy where it is continuous – a “spectrum”.

    I’m in haste so maybe next time could explain better.

    1. Perhaps Fuentes is arguing for a wave–particle duality of sex in which it is either discrete or a spectrum depending on the argument that he is trying to make at any given point in time?

  10. There is an excellent essay on bathroom issues by Holly Lawford -Smith, “The Never-Ending Dispute over Public Bathrooms” in her book, “Sex Matters”. She argues that trans rights should not come at the expense of safety of women and girls, and we need to be aware not only of the needs of trans women, but also of risks in public bathrooms of voyeurism, exhibitionism and assault. Bathroom policy should respect all stakeholder groups. She lays out solutions for new builds and existing buildings.

  11. This is very good, and I appreciate you taking on this vexatious issue. There are people whose knowledge and stature I admire. But I wince when they are soft on “sex spectrum”. (Well, heck, who agrees on everything — it’s a question of proportion)

    But also, there is this, maybe a minor point in this whole post, but from what I have read and heard, it’s very important to a lot of women,:

    …” 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.)”…

    If I understand the above, you think we should not have (public) bathrooms based on natal sex

    Please consider this: Bathrooms (also, changing rooms, locker rooms) — the UK women (Sex Matters et al.) have been articulate in framing this as women’s rights issue. Helen Joyce, for example, has been thorough and eloquent, explains the history of sex-protected spaces and the reality of women’s vulnerabilities — paraphrasing:

    A woman in a man’s bathroom can be an embarrassment. A man in a women’s bathroom can be a threat.

    She further points out with the need for sex protected spaces, the people who want to breach those boundaries may well be precisely the ones women need to exclude. I find her and other womens’ arguments on this case to be convincing. If people who absolutely cannot accept their natal sex and can’t bear go into sex-based bathrooms, I think they need separate accommodations.

  12. Jerry wrote:

    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).

    This social origin hypothesis is false. How do we know that? You compare untrained women with untrained men. Any sex differences in musculature and bones cannot be explained by invoking gendered training dynamics since you are compairing untrained individuals. Such comparisons have been made. I suggest reading:

    Emma N. Hilton & Tommy R. Lundberg: Transgender women in the female category of sport: perspectives on testosterone suppression and performance advantage. Sports Medicine, 2021; 51(2):199-214 (free access at the publisher’s site)

    Fuentes wants to invoke the cultural authority of science to support the radical trans agenda. The problem is that people will only grant authority to science if it is perceived as unpolitical (a neutral arbiter of factual claims and explanations). A soon as scientists join the political fray, they are just another set of political actors – and their demands that they speak with the authority of science are likely to became unpersusasive.

    Fuentes’ book is about how we should define sex. That is not even a question that admits of a true answer. As the famous philosopher Karl Popper (1902-1994) used to say, definitions are statements that are not capable of being true. We assign meaning to words by convention, by agreement (the same way we decide on which side of the road we drive – in the US it’s on the right side, in the UK it’s on the left side). The reason for why scientists prefer one definition over another is differential usefulness when it comes to explaining things (the main business of science). So for Harvard professor Sarah Richardson (in her review of Fuentes’ book in The Lancet) to accuse the proponents of the gamete-based definition of sex of sophistry, which means false argument, is mindboggling. She is making a category error. Definitions are not capable of being true. They are more or less useful. So Fuentes and his followers need to convince us that his preferred definition of sex has higher explanatory power than the gamete-based definition. Of course, Fuentes has done no such thing in his book; he hasn’t even tried. (Anthropologist Ed Hagen highlighted this failing in his review of Fuentes’ book.)

    1. “Even differences in musculature and bones that mandate the creation of men’s vs women’s sports, Fuentes suggests, have a social origin …..”

      According to Wikipedia, Augustin Fuentes is a “primatologist” and a “biological anthropologist”. It is particularly silly for someone allegedly knowledgeable about primates to maintain this. Would Fuentes care to maintain with a straight face that the differences in musculature and bones of a male silverback gorilla and a female half his weight have a social origin? Granted, humans aren’t as sexually dimorphic as gorillas or chimpanzees, though perhaps as much as bonobos. What about other mammals? The difference of strength (as well as temperament) between bulls and cows is HUGE. For an extreme example, we can consider elephant seals. Would Fuentes wish to argue that the physical differences between male and female sea elephants are caused by different socialization? I laugh. Or would Fuentes maintain that, unlike almost all mammals, humans are uniquely NOT subject to significant biological sexual dimorphism. Personally I think he knows full well that he is full of it and he writes his nonsense with intellectual malice aforethought.

      1. Surely Gender Theory scholars have explained that the sexual dimorphism of cattle, gorillas and elephant seals was imposed on these unfortunates by European colonialism, or possibly by Zionism, and is maintained by Implicit Bias. A paper arguing these conclusions will soon be submitted to the scholarly journal Gender, Place, and Culture.

  13. Every human is immutably binary male or female. That includes all those with DSDs, a subset of which are known as intersex conditions.

    Here is an interesting piece about the differences between intersex conditions and DSDs by Colin Wright. He explains that many DSDs are not intersex conditions, and the true percentage of intersex births is only 0.018%.

    https://www.realityslaststand.com/p/intersex-is-not-as-common-as-red

    Trans activists have dragged people with intersex conditions into their ideology, even though the conditions are nothing at all to do with being trans. This is despite their organisations issuing pleas to leave them alone. TRAs also persecute those with DSDs. An acquaintance was chased off X with stress, when some of them kept insisting that he wasn’t a ‘proper man’ as he has Klinefelters.

    International Intersex Forum, Malta Declaration (2013):

    “No-one should instrumentalise intersex issues as a means for other ends.”

    Darlington Statement (2017):

    “Intersex is distinct from other issues. We call on allies to actively acknowledge our distinctiveness…and respect the intersex human rights movement without tokenism, or instrumentalising, or co-opting intersex issues as a means for other ends.”

      1. There is no exception to the rule that mammals are immutably binary, male or female.

        If anyone produces a peer reviewed paper proving this wrong, then they can go to the Nobel committee and collect their Nobel prize for disproving 200 million years of nammalian evolution.

        1. … errrrmm .. this is a thing – exceptions proving the rule … I thought it was accurate, for this, but maybe not…

          Or “corner cases”

          They agree with the model, though they appear to refute it…

          ?

          1. I was interpreting the expression as ‘if there is an exception to it, then there’s no rule’ but i’ve just asked Mr Google, and apparently that expression can have different meanings, one being that if there is an exception, then it proves a general rule. The example they gave was that if there is a sign saying parking is banned between 9 & 5 then the rule is that parking is allowed at all other times. I hadn’t thought of it that way.

            It’s interesting to learn new interpretations 👍.

        2. No exception? It is VERY rare, but there are pseudohermaphroditic individuals that have both testes and ovaries. Such individuals can be said to be both male and female. They cannot, of course, be reproductively capable as both male and female and usually are sterile as either male or female. Genuine hermaphroditism (simultaneously reproductively capable as male or female) such as occurs in annelid worms has never been observed in any mammal as far as I know.

          1. I know it’s is possible for a male to have remnants of ovarian tissue and for a woman to have remnants of testicular tissue, but the only case I have seen where there was a claim for someone to have both testes and ovaries was a very old photograph of a male being autopsied where they claimed that odd shapes in the photo were eggs.

            I learned that bodies develop by either the Müllerian or Wolffian route and, although development can go awry, leading to abnormal development, it can’t complete both routes fully, so a human cannot impregnate themselves. Presumably their genes and chromosomes would come into play to help determine the gametes that they were meant to produce.

            But I’m certainly open to following the science and would be interested in any science papers you can share.

          2. Yes, Luana and I reference this in our paper. I think that, over history, one person with ovotestes was capable of producing sperm that could effect fertilization, and another person who could produce a child. Nobody could do both–or rather, we have no evidence of anybody doing both.

  14. “Gendered training dynamic.” God, that’s so insulting to women athletes. If only Melissa Bishop had tried harder she could have shaved a full 2.3 seconds off her 800 m time (1:57.02) and beaten all the dudes who won medals in the women’s 800 at the Rio Olympics.

    Almost as bad: Caster Semenya’s gold-medal time of 1:55.28 is nine seconds slower than the qualifying time to enter the competition in Rio (1:46). Racing as a man he would have stayed home, not won Olympic gold.

    1. Yup, that race was a disgrace and the three fastest women should be awarded their medals by the IOC. Sadly, I’m not holding my breath.

  15. “why we should not have bathrooms based on natal sex. (I happen to agree with the latter point but not the former.)”

    Single-sex toilets are far safer than “gender-neutral” ones, because they allow gaps below the doors so that if someone collapses inside the cubicle (for example, from diabetes, epilepsy, cardiac arrest, etc.)they can be seen and rescued in time. Men gaining access to female-only facilities also puts women and girls at risk of voyeurism (e.g., through the placement of hidden cameras). Women’s single-sex facilities for occasions when they are vulnerable through being partially or completely undressed, etc. are necessary for their privacy, dignity, and safety. And if you allow one man in – because he “identifies” as a woman , whatever that is supposed to mean – you effectively allow all men in, as the UK’s Supreme Court ruled in April. Either a space is single-sex or mixed-sex – it can’t be both. And for the reasons above, single-sex is preferable by far. (Men deserve privacy and dignity, too, although women generally pose less of a threat to their safety than vice versa.)

    1. Apologies, I commented without refreshing the page and didn’t see my points has been made more eloquently by others already. Oops!

  16. Im interested to hear more about your view that ‘bathrooms’ shouldn’t be based on ‘natal’ sex. Why do you think that?

    The bathroom debate is a proxy debate for other single sex space such as: locker rooms, prisons, sports, refuges etc.

    If men are allowed in women’s bathrooms (we call them toilets here in Australia, no-one is having a bath in a shopping centre toilet block), why not let them in all the other single sex spaces. ie. why not just abolish all women only spaces? What would be your best argument?

    1. I explained my views above. Thinking about it last night, I think that people should use the bathrooms of their natal sex. However, that might be difficult to enforce if the trans person is not identifiable as a member of their natal sex because of surgery, hormones, clothes, etc.

      So I don’t have a best argument.

      1. How does this sound as a solution to the enforcement issue? Agree it’s not trivial. We revitalize the social taboo, backed up by legal enforcement, that men must not enter women’s bathrooms. If a man does so in a totally surreptitiously way that he doesn’t get busted by other women, he might get away with it. A woman who suspected he was a man (in drag or not) could call security/police, with the expectation that the police would treat it as an offence like sexual assault, and would arrest as per the law. It would be up to the police to investigate and collect whatever evidence they needed, which could include physical examination.

        At any arts event these days, you’ll see lots of people in costumes that do make it hard to tell. If a bearded breastless person passed behind me heading for a stall while I was standing at a urinal, I wouldn’t think anything of it, even if it turned out she was a woman. How would I know? I have seen ordinary feminine-looking women enter men’s bathrooms “because our line was too long”. But men aren’t worried about their safety from female interlopers.

        It’s not necessary that every single entry by men into women’s bathrooms be caught and punished, only that a man who does get caught can’t use the defence that he was following his gender instincts and was innocent of any wrongdoing. And the police should not be able to say, to complainants, “Sorry, our hands are tied by human/civil rights laws.” The more such men threaten violence against women who stand up for women’s protected spaces, the stronger the women’s case is for punitive enforcement.

  17. On September 8, 2025, I attended via Zoom a presentation by Steve Novella on why skeptics disagree about God and gender. I registered to ask Novella some tough questions, and I asked some of them.

    Novella was all over the place re gender. While he didn’t mention any names, he sounded puzzled, disgusted, and angry about why “certain evolutionary biologists” disagree with him about sex being a spectrum.

    Novella confused biological sex, “gender identity,” and even sexual orientation to make his case. At one point, he even said that someone with a DSD is “obviously a woman because she married a man.” (Uh, hello?? Men do marry other men. How could Novella not know this?) Yes, he used the canard of people with DSD, a reductio ad absurdum if there ever was one.

    During his talk, he said that biological sex is as inconsequential as calling Pluto a planet or a dwarf planet. He added that anyone “wanting to categorize people by sex” is either misguided or a bigot.

    I asked him how I know whether I am a female or a male since Novella said that neither gametes nor genes determine biological sex. He replied that he didn’t know, as biological sex “depends on the context.” He then asked me “why is this important to you if you’re male or female?” Facepalm. Major facepalm. I replied that I need to know my IDENTITY as a female or male. Novella repeated that my biological sex is unimportant.

    Then the moderators cut me off.

    Humanists and Freethinkers of Fairfield County HFFC, Connecticut) hosted Novella. They sent attendees an email which I’ve excerpted:

    “Thank you for registering for HFFC’s program featuring Steve Novella on Monday [9/8/2025] evening. Those who were able to join in-person or via Zoom saw a really interesting discussion about several areas where the skeptic community has disagreed over the years. We sent a warm thanks to Steve… If you missed the program, the good news is that in a month or two we will post a video excerpted part of Steve’s presentation.”

    Gee, I wonder which parts HFFC will cut..?

    I will keep WEIT updated if/when HFFC posts the “excerpted” presentation.

    One more thing — 3 men in the chat attempted to mansplain to me what a woman is. All of them agreed with Novella that sex is a spectrum and also completely trivial.

    SMH. Just SMH.

  18. Non-Westerner here. I do not know why you all in the Western world are being so weird about this. Anyone who claims sex is a spectrum should just be invited to milk a bull, even a castrated one, or to rear a cock for eggs.

    My country has mandatory military service for males and is very strict about it, so no worries about self-ID here, at least in the near future.

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