Stephen Knight on Sean Carroll, Colin Wright, and the binary of sex

November 16, 2022 • 9:15 am

Sean Carroll, bless his physicist’s soul, decided to respond to a tweet by Colin Wright (asserting the binary nature of sex) by giving his (Carroll’s) own take in on the biological nature of sex. Sean attached a figure from an old Scientific American article assertingthat sex is not binary, but a spectrum. Here’s the first to-and-fro:

The figure, enlarged (click further to make it even bigger):

This figure came from a Scientific American article published in 2017 by Amanda Montañez, called “Visualizing sex as a spectrum” (free access).  The article clearly implies that, like gender, sex is not binary but a spectrum:

Much of the public discourse in this arena centers on gender rather than sex, presumably because gender is understood to be somewhat subjective; it is a social construct that can be complex, fluid, multifaceted. Biological sex, on the other hand, appears to leave less room for debate. You either have two X chromosomes or an X and a Y; ovaries or testes; a vagina or a penis. Regardless of how an individual ends up identifying, they are assigned to one sex or the other at birth based on these binary sets of characteristics.

But of course, sex is not that simple either.

The September issue of Scientific American explores the fascinating and evolving science of sex and gender. One of the graphics I had the pleasure of working on breaks down the idea of biological sex as a non-binary attribute, focusing largely on what clinicians refer to as disorders of sex development (DSD), also known as intersex.

This figure clearly has an ideological purpose:

DSDs—which, broadly defined, may affect about one percent of the population—represent a robust, evidence-based argument to reject rigid assignations of sex and gender. Certain recent developments, such as the Swedish adoption of a gender-neutral singular pronoun, and the growing call to stop medically unnecessary surgeries on intersex babies, indicate a shift in the right direction. I am hopeful that raising public awareness of intersex, along with transgender and non-binary identities, will help align policies more closely with scientific reality, and by extension, social justice.

In reality, what they are trying to do is the reverse: adjust scientific reality so that it aligns with social justice. That is, if sex is a spectrum and not binary, then people of different genders can somehow feel that they are in harmony with biological reality. But that’s an example of the “appeal to nature.” The rights of people of different genders, including transsexual people, do not depend on the developmental biology of sex, or of any observations in nature about sex dichotomies.

I’m not going to discuss my claim that sex is binary; I’ve talked about it at length, as did Luana Maroja in her piece at Substack. I’ll just put it out there that the going biological definition of sex is that there are two sexes in vertebrates: males (who produce small mobile gametes) and females (who produce large, immobile gametes). There is no group that produces intermediate types of gametes that can unite with other gametes, so there is nothing beyond these two sexes. Further the exceptions to this male/female distinction (intersex folks and hermaphroites) constitute about 0.018% of the population. or about one in every 5600 people. For all intents and purposes, then, sex is binary.  Gender, in contrast, is less binary but still bimodal, since most people identify their gender (i.e., how the present their social sex role) as male or female, too.

Carroll, however, got into trouble by issuing the tweet above, which, as his caption noted, purported to represent the views of “actual science”. In reality, it represented the “progressive” ideological views of Scientific American. In light of the magazine’s steep decline, we can no longer take its word for what accepted science tells us.

If you follow the thread on Sean’s tweet, there are of this morning 737 comments—most of them critical and many explaining why Carroll’s notion that he’s showing us “actual science” leading to a non-binary view of sex is wrong.  I didn’t go through them all, but posted a few in yesterday’s Hili Nooz.

(One note: I didn’t know that Sean had left Caltech, but this is pinned to the top of his feed):

What the Sci. Am. figure actually shows is that the pathways determining sex-related traits (note that “gametes” are not shown!) is complicated, and if your definition of “sex” includes secondary sex characters, chromosomes, and so on, then lots of things can go wrong, producing intersex individuals. Still, only one individual out of 5600 represents one of these developmental anomalies.

I responded, and I swear that this is by far the most comments (195), retweets (1,529), and “likes” (8,258), I’ve ever gotten on any of my tweets. But it’s best not to feel good about that, because it only makes you want to get more approbation on Twitter, which is not a good reason for tweeting.

But the point of this is not to bash Sean, whom I like and who is our Official Website Physicist®, but to correct what he said. I hope he addresses the critics and hope even more that he admits that biological sex consists of two distinct groups with very few exceptions.

Stephen Knight, once known as the “Godless Spellchecker,” has a piece about the kerfuffle on his Substack site. You can read it for free by clicking on the screenshot below, but, as always, subscribe if you read often.

Stephen gives a tweet from Colin Wright, who’s written a lot about the binary nature of biological sex (see this post, for instance), and then gives his (Stephen’s) own take:

Below are excerpt’s from Knight’s piece. He’s pretty hard on Sean in a way I wouldn’t be, because Carroll is a nice guy and just made a misstep. But I’ll quote Knight anyway:

 Colin Wright is an evolutionary biologist stating an objective fact about the biological reality of human sex. This isn’t a mere opinion—it’s a scientific fact. There are few things in the field of biology that are so emphatically true as human sex being binary is.

If anyone were able to demonstrate that human sex wasn’t binary and immutable, their research would win them a Nobel prize and revolutionise our entire understanding of biology. But no such peer-reviewed research exists—for obvious reasons.

This doesn’t stop people that really should know better from from wading in with this sort of stuff though.

He then shows Carroll’s tweet.

Knight continues, and gives some Twitter responses from Emma Hilton, a Manchester Uni biologist (Matthew’s colleague) who also studies and lectures on sex determination.

Sean seems to arrogantly think he has the ‘actual science’ on his side when rejecting the binary nature of human sex. But in reality, all Sean is doing with this borrowed graphic is using the existence of intersex conditions as a jumping off point for some faulty conclusions.

The existence of intersex conditions or DSDs (difference in sex development) appears to be the graphic’s sole argument against the gender binary. However, although intersex people do exist (as a tiny minority ) they do not constitute a third or separate human sex. In fact, certain intersex conditions are entirely sex-specific—meaning some of them only affect men, and some of them only affect women. And the idea that someone with a ‘micropenis’ or an abnormally large clitoris is no longer unambiguously male or female is as false as it is harmful.

Development Biologist Emma Hilton highlights the peculiar claims within the graphic when she notes:

Another from Emma. (“DSD” refers to “disorders of sex development”):

Sean doesn’t appear to have replied to Emma’s (or anybody else’s questions).

Here’s Knight in a 9-minute clip of a discussion he had with Colin Wright, who explains why sex in humans is binary. If you haven’t read my own discussions on this site, Colin gives a good summary.  I should add that I’ve found a single case of an individual who produced both types of fertile gametes, a true hermaphrodite. The person apparently both ovulated and fathered a child (Wright mentions the possibility of such an individual at 4:47). But this is not, as Colin explains, a member of a third sex, but an individual combining both sexes. Nevertheless, one could count such a hermaphrodite as an exception to the binary, as Sax (2002) did when deriving the 0.018% figure for exceptions to the sex binary (mostly intersex individuals).

Wright also dispels the 1.8% figure of “nonbinary” individuals bruited about by Anne Fausto-Sterling. Though she later rejected her own figure, people are still using it. Either they haven’t followed the literature, or they know better but choose to hide the revisions.

Wright helpfully explains and dispels the ideological point of view that drives people to distort biological truth in this way:

I suspect the willingness to unthinkingly push pseudoscience of this sort is well-intentioned. People seem to believe that one must reject the human sex binary in order to ensure transgender rights.

First of all, intersex conditions are mostly not applicable to the trans debate—as the overwhelming majority of transgender people do not have an intersex condition—and it shouldn’t matter whether they do. Not to mention many actually living with intersex conditions aren’t too keen on their existence being used as a gambit in the spread of gender ideology either.

You don’t need to pretend humans can change their sex to be able to defend trans rights. It’s the equivalent of demanding we must agree the world is 6,000 years old in order to guarantee religious freedom.

If you use false premises to argue for certain rights, many will feel inclined to dismiss the validity of these rights along with your junk justifications. Not only is all of this completely unnecessary in the fight for trans rights, it can be counterproductive too.

All that is needed to advocate for trans rights is a commitment to individual liberalism. That’s it. Pushing false claims about gender as a condition of certain rights turns your cause into a religion. And I will invoke the very same liberalism I use to defend trans rights to reject your new faith. There is no contradiction here.

Why do I bang on about this (I think this is the last post about binary sex for a while)? Because I simply can’t stand people distorting biological reality in the service of ideology. This isn’t going to kill people, as Lysenko’s bogus “vernalization” theory did, but it still confuses and misinforms people, and infuses our field with an ideology that has spread to scientists themselves—as well as journals and granting agencies—who chill the atmosphere for free discussion. And that impedes the search for truth that is science.

Click “continue reading” to see screen capture of the original “sex” tweet by Carroll, which I’ve saved in case the original tweet goes away:

127 thoughts on “Stephen Knight on Sean Carroll, Colin Wright, and the binary of sex

  1. One might wonder why Carroll felt it necessary to weigh in (wrongly, of course) on a topic within a scientific discipline which is not his own. A cynic might be inclined to suspect that virtue-signaling (a form of moral preening) is the cause.

    1. I‘m inclined to believe that until I hear a better explanation, as I don‘t think that he is THAT stupid. Maybe something to do with his new employer?

      He quickly blocked replies, including such things as rebuttals from biologists, on Twitter.

    2. Sadly, Sean has a woke streak. He starts from the presumption that, on moral grounds, woke people are in the right, so just presumes that the science supports them. Hence, he Tweets on the topic without having looked into it or being aware of the counter-arguments.

      1. Yes Coel, I noticed the woke streak in Sean too, which was a bummer.

        I’m a big fan of Sean – we need more philosophically aware scientists (I put Prof CC in that category too, which is one reason I enjoy this site). But when Sean gets to commenting on identity politics stuff I get squeamish and “oh no, not you too!”

      2. I think Lord Kelvin (William Thomson), ‘disproving’ Darwin’s evolutionary theory by showing the Earth could not possibly be more than a 100 million years old (he settled on 20 to 40 million), is another good and notorious example. (He dismissed stratigraphic evidence and fossils -not his field-, but he failed to reckon with, or underestimated, another possible mechanism for the Earth not cooling so fast, ic. radioactive decay)

        1. I don’t think it’s fair to regard that as a “good and notorious” example of a physicist improperly crossing fields. The age of the Earth was pretty much unknown at the time, the geological estimates based on stratigraphic evidence were vague and wildly uncertain. Kelvin attempted the first substantial calculation. He was wrong — for reasons he couldn’t have known at the time — but this is a case of science working well, advancing by trying out ideas and then improving on them.

          1. I respectfully beg to disagree, at least somewhat. The stratigraphists had serious arguments for a much, much older Earth. For reasons he couldn’t have known at the time? I’m not firm on the timing, but I think he knew about radioactive decay, he just didn’t check it’s possible importance. Whichever way, Thomson arrogantly dismissed all of the stratigraphists’ monumental works in a one page article.
            At least he got his comeuppance.

          2. After some Googling: Thomson’s first estimate of the age of the Earth was 1864 (though he repeatedly refined his estimate in subsequent decades). Radioactivity was discovered only in 1896, and the finding that radioactivity released heat was 1903. Indeed, (wiki) “Rutherford famously made the argument in a 1904 lecture attended by Kelvin that this provided the unknown energy source” (40 years after Thomson’s original estimate and by then Thomson was 80).

            But, also, Thomson’s age estimate was backed up by his estimate for the sun (presuming that the Earth wasn’t older). Knowing why that is wrong needs knowing about the atomic nucleus (discovered 1911 by Rutherford) and then about nuclear fusion (not known until the 1930s).

            So, it might be fair to say that that Thomson was too dismissive of the stratiographists estimates, but overall I think it’s fairer to see this episode as the normal process of science, with wrong ideas being superseded.

    3. A famous physicist (who won the Nobel prize for chemistry) once said that all science is either physics or stamp collecting. It seems that some physicists think that, since they mastered the boss science (as they see it), they also know best about all the other sciences. A classic example would be Fred Hoyle and his panspermia nonsense.

      Sean could have fallen foul of this trap, or it could be he found a pretty picture that seemed to support his point of view and didn’t check it carefully enough. In particular there are a number of conditions listed on the spectrum between male and female that he failed to look up and it’s clear that, if that line is supposed to represent a spectrum, they are in the wrong order.

      1. Just to note that this “stamp collecting” line, while often repeated, is of dubious provenance. It is most commonly attributed to Ernest Rutherford, but that seems to have been originated by someone writing several years after Rutherford’s death. Is there any bona fide citation to any famous physicist actually saying this?

  2. Colin Wright’s contention that the claim that the sex is binary is not the same was the claim that every human can be unambiguously classified into either male or female is interesting. I would think that many who claim that sex is not black and white, but rather a spectrum are asserting the latter and it is the latter that has social implications.

    1. Even then it’s a complete red herring. The existence of DSDs really has no bearing on the trans issue at all. Hardly any trans person has a DSD, they are unamiguously male or female.

      1. It may be a different issue, but it is related to whether you think there are binaries in biology rather than populations that exhibit diversity of form and behavior

        1. Gregory, I agree with a lot of what you say in this thread, maybe 80-90%. I’d recommend you tone it down for now, though. You’re at 10 of the 82 posts in this thread, and we’re supposed to keep it below 10%.

          I’m not going to say that our argument is a lost cause on this site, but many people here are too emotionally invested in how sex relates to trivial social issues like sports, so they keep trying to reinforce a sexual dichotomy – which does hold true for 99.98% of humans. Once there are no further social implications of actual sex (from sports to selective service), I think biologists will be able to discuss the topic with little blowback from the PC crowd.

          Socio-politically, it looks like there are three broad categories of views: that people should live in (some of) the social roles of the sex they are born into (sports, etc.) (this view seems to predominate here), that people can choose their own sex and social roles (that view is frequently demonized here, not particularly represented), and that society should ignore sex and gender entirely, and leave biology to the biologists, not the general public (some people here hold that view). It seems like progressive culture is divided between the second and third views; I adhere to the third. I characterize the first as Right, the second as New Left, and the third as Libertarian.

          1. “… people should live in (some of) the social roles of the sex they are born into (sports, etc.) (this view seems to predominate here), “

            No, telling such people how they “should” live is not the dominant view here. Rather, it is saying that if women want sex-segregated sport, then the request is legitimate, and should be respected.

            Meanwhile, trans people should be free to live their lives however they wish; really, we don’t care, we’re fine with them! But, they should not encroach on other people’s quite legitimate rights to single-sex spaces.

          2. Insisting that girls and women have separate spaces to protect them emotionally and physically from men is hardly a “trivial issue,” be it in women’s sports, women’s shelters or women’s prisons. It’s all the same issue.

        2. Every mammal that has ever reproduced has done so either by producing oocytes or sperm: 2 reproductive roles. An individual not capable of reproduction is not relevant to the definition of a reproductive method. Further, any definition of the sexes has to work in a comparative context (unless you are a creationist).

    2. Only one individual out of 5600 can’t be unambiguously classified, and that’s what Wright admits. To me, that is for all intents and purposing a binary–and it’s certainly not a spectrum. Those who crow that 1/5600 are “exceptions” and show non-binary-ness are acting out of desperation.

      1. I know I’ve scrutinized the word “binary”, and still I struggle for the best words – but perhaps what might help here is to recognize we are always using a _model_ – a _model_ of sex in humans that is either male or female, of course, but – as statistician George E. Box stated :

        “… all models are approximations. Essentially, all models are wrong, but some are useful. However, the approximate nature of the model must always be borne in mind….”

        Box, G. E. P. (1979)
        “Robustness in the strategy of scientific model building”, in Launer, R. L.; Wilkinson, G. N. (eds.),
        Robustness in Statistics
        Academic Press, pp. 201–236,

        And in particular:

        “Worrying Selectively:
        Since all models are wrong the scientist must be alert to what is importantly wrong. It is inappropriate to be concerned about mice when there are tigers abroad.”

        Box, George E. P. (1976)
        “Science and statistics” (PDF)
        Journal of the American Statistical Association, 71 (356): 791–799

        for links/etc. see

        ^^tried to keep it short – it is not a criticism – I’m just trying to add to discussion.

        1. TP, I’m a fan of George Box and his critique of models. But the sex binary is not a model. There are only two gamete types in any species of animal or plant. This is the ontology of the problem.

          But it can in rare cases be hard to know which gamete type is found in an individual (e.g., some folks with DSDs). This is the epistemology of the problem. In other parts of this thread commenters are mixing one for the other, and arguing that because the epistemology is very rarely ambiguous therefore the ontology is wrong. I think that’s an error.

          1. OK, but why can’t sex as it pertains to reproduction of organisms be a model?

            Our minds model practically everything, if I understand the writing out there – sort of models all the way down.

          2. Because a model is an approximation of or a metaphor for something in the world that has more dimensions or parameters than can possibly be contained in the model itself. This is what makes a model both wrong (not all real parameters are represented in any model) and useful (if the most important parameters are included in a particular model).

            But there are only two gamete types. A “model” of sex can have only one parameter (number of gamete types) because there’s only one parameter in the real world of sex, and the parameter has only two possible values (sperm or eggs). There is nothing unknowable about that or missing from the “model”.

          3. “A “model” of sex can have only one parameter (number of gamete types) because there’s only one parameter in the real world of sex, and the parameter has only two possible values (sperm or eggs).”

            In mammals – but wouldn’t the model of sex incorporate that of reproduction, crossing, and everything that gametes are doing? How we understand mammals – or living things – get their genes into the next generation? The model of sex is useful, because we make good predictions with it.

            “sex” by itself would mean what to an alien who wanted to know? The alien would wonder why a gamete is important – and would be interested if there were a pair that explained embryogenesis.

            I still think sex can be a primitive model, like triangles are models, like a bottle is a model, or a hand – an essential archetype which we use before the observation is made of a triangle drawn in the sand, or a 2 L bottle pours water, or a gibbon uses a hand to eat food.

            But I’d be interested to know if anyone else recognizes this – I’m just chatting at the proverbial water cooler here.

          4. It’s a fun water cooler!

            Ok sure but now you’re talking about sex as a process – how to successfully reproduce. The conversation on the thread is about sex as a state – how many are there?

            There’s a long technical explanation why sex and reproduction as processes are not the same thing. Sex as a process is specifically about genetic recombination and not necessarily about reproduction; one can have sex & recombination without reproduction (bacteria do it all the time); and reproduction can happen without sex (lots of animals and plants and other things that have asexual budding or cloning without meiosis).

            The explanation why sex as a process is about genetic recombination is way too complicated for a comment here. I sort of hope someday our host might write a post about this, and about why meiosis (which divides the genome of each parent in half) and recombination explain the evolution of exactly two gamete types (which fuse together to restore the original genome complement in offspring) and two sexes in most sexual organisms.

          5. OK, but I’d say those are all models of some sort – some powerfully scientific ones, and some conceptual, or primitive, perhaps – at least patterns – that everyone uses.

            When the observations do not fit the model – apparently the impetus for the Scientific American piece … is what I am getting at … the sleep of reason breeds monsters.

          6. Just want to share this quote – I’ve rambled enough :

            “… the sciences do not try to explain, they hardly even try to interpret, they mainly make models. By a model is meant a mathematical construct which, with the addition of certain verbal interpretations, describes observed phenomena. The justification of such a mathematical construct is solely and precisely that it is expected to work—that is, correctly to describe phenomena from a reasonably wide area.”

            -John von Neumann, 1965
            In “Method in the physical sciences”
            Bródy F., Vámos, T. (editors)

            Detailed ref. :

          7. Thank you, Mike.
            Ontology vs. epistemology, key to unraveling the entire protracted discussion. That and careful accounting for polysemy of the terms ‘sex’ and ‘gender’.

            Binary sex–the state, not the process–is not a “model.” It is data. Direct observation, replicated again and again, every time anybody has looked.

          8. “Binary sex–the state, not the process–is not a “model.” It is data. Direct observation, replicated again and again, every time anybody has looked.”

            Models are fit to observations with a small number of parameters.

            How are the observations made? Patterns have to be recognized. Where do the patterns come from? A model that everyone uses, precisely because it is useful in the way the streetlight is useful for finding the lost keys. Where did the model come from? Prior observation and model building – and also rejection of models that do not make accurate predictions.

      2. I don’t think you need to grant even the “for all intents and purposes” concession, Jerry. Even that one individual is made up of two binary gamete-determined elements, male and female, which happen to co-exist in the same body through an accident of zygosity. There is no “spectrum” in that one individual, any more than there is in the population. To me, that’s an exception that “proves” the rule in its intended sense of “testing” the rule (sex is binary) and finding that the rule survives because of what we know about the exception.

        That individual is both male and female. S/He is not “in-between” or “third-sexed”. S/He will have to make up his/her own mind about how to present socially but that does not alter the binary nature of his/her gonadal/genetic anatomy.

        I’m not objecting to the “for all intents and purposes” view, just worried that it leaves a chink in the armour for the ideologues to work a screwdriver into and say, “Aha! So you admit that sex is not binary in every single human on earth!” Still, you’re more practised at this then I am, so I defer.

        1. Sorry. My “gonadal/genetic” is a mis-statement in the penultimate paragraph. I meant “gonadal/gametic” and missed the incorrect auto-correct. Apologies.

  3. “you don‘t need to pretend humans can change their sex to defend trans rights“

    True; mixing up sexual-development disorders with the whole trans discussion is very bizarre, to say the least. But the quote above implies that there is such a thing as “trans rights” and that they should be defended, which is far from obvious, to say even less.

  4. I’m really grateful Jerry is sharing my writing/videos here, it is most appreciated. I’m especially pleased that Jerry continues to hold fast and true to science over faith.this feels like an increasing rarity on the topic of gender. One quick note though, the quotes that directly follow the sentence ‘Wright helpfully explains and dispels the ideological point of view that drives people to distort biological truth in this way’ are actually my words, not Colin’s.

    Thanks again for covering this.

      1. Yes. Your words “Wright helpfully explains and dispels the ideological point of view that drives people to distort biological truth in this way” should read “Knight helpfully explains and dispels the ideological point of view that drives people to distort biological truth in this way” because the indented quote that followed are the words Stephen Knight said, not what Colin Wright said.

      2. I think you just accidently typed ‘Wright’ instead of ‘Knight’. Should read ‘Knight helpfully explains and dispels the ideological point of view that drives people to distort biological truth in this way’, because what follows is a quote of my writing, not Colin Wright’s. Thanks again!

  5. Thanks, Jerry. I hope that Sean will have one of his next Mindscape episodes on this topic with someone relevant. I must say you wouldn’t be a bad guest!

  6. “Why do I bang on about this (I think this is the last post about binary sex for a while)? Because I simply can’t stand people distorting biological reality in the service of ideology. This isn’t going to kill people, as Lysenko’s bogus “vernalization” theory did, but it still confuses and misinforms people, and infuses our field with an ideology that has spread to scientists themselves—as well as journals and granting agencies—who chill the atmosphere for free discussion. Ant that impedes the search for truth that is science.”
    For me, the worst side effect of this kind of nonsense is that erodes public confidence in science as a whole. I believe it is really corrosive and is causing long term damage.

    1. PCC(E): “In reality, what they are trying to do is the reverse: adjust scientific reality so that it aligns with social justice.”

    2. the worst side effect of this kind of nonsense is that erodes public confidence in science

      I’m wondering if it might be time to consider the current generation a ‘lost generation’ and leave it at that. Let the science of sex be lost for a decade or two. We’ve already lost enough public trust in a LOT of biology over the past 20 years. Keep an undercurrent of biological knowledge alive and well somewhere (US, nope; Canada, nope; UK, nope; NZ, nope; Germany, nope; Scandinavia, nope; … maybe Australia?). By the time the next generation rediscovers the need for biology, we will have forgotten social gender roles and their associations with natural sex, and we can move forward with biology again.

      I’m not sure how serious the suggestion is, but the PC movement seems like it’ll be relatively unstoppable for the next decade or two.

  7. Oh dear, sometimes people are born with six fingers, sometimes with four or three. We should stop thinking of Humans as being five-fingered, clearly the number of fingers is on a spectrum!

    Not only is Carroll a fool, but his lack of a response shows he is a coward as well.

    1. I know you present this as a reductio, but I am inclined to say a certain percentage of humans do have six fingers, so it is only an approximation to say we humans have five fingers on each hand. If you disagree, what percentage is the threshold? Do you want to say that humans are right handed?

      1. “Do you want to say that humans are right handed?”

        I would say that humans are either right-handed or left handed; a binary. People born without one or the other (or an additional hand), does not change that binary.

        In end, this is nothing more than a word game. I think you know that.

        1. This right-handedness is actually an apt analogy as there are some people who are ambidextrous and some people are more right handed than others — so I see a spectrum here too, albeit one where most people are close to the poles. It also mirrors the social pressures of the day–in the past many people who were naturally more left handed were forced to write with their right hands in school.

          1. yes, Dr MacMillan’s abmonition below about using analogies is apropos. I should not have done it.

            I don’t suppose you’ll address the point many have made; in humans there is no third gamete.

          2. Hi EdwardM, I am not aware of a third gamete — I don’t know enough developmental biology to know whether there are malformed sperm or eggs that one would not consider sperm or eggs. I would say that determining the sex of gametes is not the same thing as determining the sex of organisms and that the spectrum view, as far as I understand it, does not require additional types of gametes.

          3. “I would say that determining the sex of gametes is not the same thing as determining the sex of organisms.”

            Now you’ve said something that makes sense.

            In humans there are two (and only two) types of gametes; that is biological “sex”. It is binary.

            In our culture, the “sex” of a person is often made on the basis of secondary sexual characterics which in rare cases may not match their biological “sex”.

            In your arguments here you have been conflating these categories. I wish I didn’t, but I believe deliberately so.

            btw, sorry for any past typos. I do not have editting privileges and I’m a lousy typer

          4. The gametes are the sex. That is the whole point of everything and the come in two, no overlapping forms. Either a large, nonmotile one (female) or a small motile one (male). The sex of the organism is just that and the body is built around that germ line as a delivery and protection shell. Sex determination is just easier in 99.9% of cases by simply looking at the phenotype and not having to dig into the gonads. The purposeful confusion of the practical aspects of sex determination with actual sex (and worst, with gender) in the name of ideology is a serious problem.

      2. Red herring. No one demands that humans be regarded definitionally as having five fingers on each hand, nor certainly that humans are right handed. The latter is absurd and is therefore a misleading analogy to what you are trying to argue about a sex spectrum.

        Surgeons have to know about anatomical variation so they don’t cut the wrong thing, thinking it is something else as the follow the body’s internal roadmap. These variants, like six fingers, are considered abnormal only if they cause trouble with body functions including body image. A cleft palate causes more trouble than a sixth finger or a residual median artery in the forearm. But none have anything to say about what humans must have to be called human.

        Humans have two and only two sexes. That in some individuals it is difficult to tell what that sex is doesn’t change that. It is not at all like having six fingers or being left handed. Argument from analogy is often a fallacy, as here.

        1. But the people who are resisting binary thinking are resisting the demand that everyone be either classified as male or female. Leslie: do you want to say that definitionally every human being has to be either male or female? Or is this an empirical question. I wonder if biologists have not fully shed typological thinking and not fully embraced what Ernst Mayr called “population thinking.” Mayr was thinking about species, but there are similar issues about variation of sexualization too.

          1. “Leslie: do you want to say that definitionally every human being has to be either male or female?”

            You should listen to the video with Colin Wright that Jerry posted…he addresses this exact issue. The answer is that there are only two sexes, but it is certainly possible that an individual could have characteristics of both. Organisms that are true hermaphrodites…such as certain snails that produce both types of gametes and therefore can self-fertilize, would not be considered a third sex, but rather organisms that are both male and female.

            It seems the only way from a biological perspective to have a third sex would be to have a third type of gamete….

          2. “It seems the only way from a biological perspective to have a third sex would be to have a third type of gamete.”

            This is what Dr PCC(e) and many others have been saying and clearly needs to re-stated at every opportunity; humans, like all other multi-cellular animals, produce two (and only two) types of gametes.

            This is biolgogical sex. Those trying to claim biological sex is a spectrum use the existence of rare DSDs, which can make which gametes the person’s genes encode for difficult to determine, as a kind of rhetorical bait and switch.

            And, as others have pointed out, it seem deeply weird to be using this line of argument in support of trans rights.

          3. Human beings don’t “have” to be anything. What they are is male, female, or if rare XX/XY mosaics, both. (Not “somewhere on the spectrum” but both poles.)

            If society wants to embrace non-binary thinking it is free to do so. It just won’t have sex science on its side.

          4. Biology can have whatever categories it wants. Sex-binary-gametes, great. But let’s not pretend there is a philosophically privileged grounding there, which you seem to be assuming.

            Overall this is a philosophical question regarding what sorting buckets should be created and used and how they should interact in society. eg; personally I think whatever fairly neatly divides “tendency and ability to excel at physical violence, sexual violence, pedophilia” and “vastly less or zero tendency to those things” is a decent pragmatic framework to decide who goes in what prison for example. But that last is the important part. There’s no such thing as “just are”, categories only make any sense in reference to their purpose.

          5. These categories aren’t made up; males and females evolved by natural selection under whatever selection pressure created sex. It’s not a philosophical question, just as “are humans and chimps different species?” is not a philosophical question. And the evolution of two types of gametes is what started all the other differences. You don’t seem to understand that.

          6. And here you are misapplying population thinking. Mayr’s comments pertained to how speciation occurred and not to the reality of species, and never to sexes.

        2. Perhaps “bipedalism” is a better analogy. Humans are bipedal…but wait, what about people born with only one leg, or three? What about rare cases where individuals cannot walk on two legs but go about on all fours (

          Hopefully, we would conclude that these developmental disorders and anomalies do not preclude homo sapiens from being defined as “bipedal” in its locomotion, and that there is no “spectrum of locomotion” within humanity.

          1. I think some of this debate is due to the loose use of generalizations. Saying “humans are bipedal” could mean 1. All humans are bipedal, 2. The stereotypical human is bipedal, or 3 It is normal for humans to be bipedal, where “normal” here could be interpreted statistically or normatively. The words “disorder” or “abnornality” too can have statistical or normative connotations. (I would also point out that most humans who are younger than two are not bipedal, as are many adults, so 1. is false)

          2. If I biologist says “Humans are bipeds”, I would take that as a statement of how we typically are and, more importantly, how we have been designed by natural selection within our lineage to optimize survival and reproduction.

            Pointing out that humans younger than 2 are not bipedal is not dispositive of this view, anymore that saying that juvenile lions that can’t hunt yet mean that lions can’t be called predators.

            Any condition that deviates from bipedalism, such as only being born with one leg, or three, or having the propensity to crawl as an adult instead of walk would seem to decrease one’s ability to survive and reproduce, and so could rightfully be called a “disorder” or “malfunction”.

            This also kind of gets to the heart of this sex discussion. The two gamete model is all over the animal kingdom…are there any cases of species that employ more than two gametes? The utter lack of a spectrum of gametes may speak to the fact that such a sexual system is unworkable in practice….

      3. The point is that the number of fingers humans have is not on a spectrum, just because there exist abnormalities! This is the problem with Carroll’s tweet, it confuses sex with developmental abnormalities as Coyne himself says. Is the analogy perfect, of course not, I made just to poke fun at the guy. Your silly pedantry has made it funnier. Thank you.

        1. Glad that you are amused. Just one last pedantic question: what percentage of people would need to have 4 fingers before you would say it is false that humans have 5 fingers? 0.018%? 0.1% 1%? 10%? What is the threshold below which we should ignore anatomical variation in our definitions?

          1. You’re missing the point, Gregory. We don’t use anatomic variation to determine sex at all. Because there is phenotypic variation, whether we consider it “normal” or not, you can’t use it for definition. Gametes are male, or they are female. If a rare person has functioning gonads of both sexes, s/he produces gametes that are entirely sperm and entirely ova, no gametes that lie on a spectrum. There is no anatomical variation in gamete production.
            Advice to everyone else. Don’t fall into the trap of arguing by analogy. All your opponent has to do is show a defect in your analogy, like “infants are not bipedal”, and claim that he has defeated your principal argument. Then you waste cognitive effort trying to come up with another analogy. Use analogy only to illustrate for the slow kids an argument that you have already proved to the satisfaction of the bright ones.

          2. Hi Leslie, I think I understand the point, but I think there are other issues at play in this debate regarding the use of definitions in biology that others are missing. In math, you can define a triangle as a figure with three sides and it is clear cut that all triangles have three sides. In biology, it seems to me, when you say “humans are bipedal” or “males produce sperm” or “humans have five fingers on each hand” you allow for the fact that some humans are not bipedal, some males don’t produce sperm, some people have four fingers, etc. Cases like this are sometimes called “generics” by philosophers and linguists. For the case at hand, the claim “humans are either male or female” allows that some people are neither male or female or at least neither only male or only female. So I was wondering if this is a generic statement that many are mistakenly thinking is a true generalization.

            Now, you could say, as people do in this thread, well for “all intents and purposes” you can treat the claim humans are male or female as true, but for the small percentage of people who don’t fit into these poles it makes a big difference to their lives. So one issue, I think, is that the terms/definitions “male” and “female” and associated generic claims have roles to play within biology, they also play important roles in larger human culture too where intents and purposes differ.

          3. >”. . .small percentage . . .”

            How can you presume to speak for that one person who ovulated and managed to father a child as to what difference it made in his/her life?

            I’ve explained elsewhere why the “all intents and purposes” refuge is not necessary tor the argument that sex is binary in all cases. If you want to say that cultural role expectations are spectral, fine, but you don’t need to have non-binary sex to make that obvious and uncontroversial statement.

          4. Leslie: You say, “There is no anatomical variation in gamete production.” I would be surprised if this is true since we have variation in nearly every biological trait. What data do you rely on to make this claim?

          5. Gregory, please, slow it down. Again, I largely agree with you, but disagree with the technique.

            Please start by reading the site’s current working definition of ‘sex’ here:

            I know I risk our host’s ire at commenting further, but if you would like to continue participating here, please take a breather. A lot of these topics have been discussed to death here, so either search the archives, or wait for them to come up again. (I know it’s not my call to advise you here – and note what Alanis incorrectly referred to as ‘irony’.)

            I’m not sure what percentage of currently living humans are currently producing sperm only, eggs only, both, or nothing at all, but that is all that is being referred to in that definition. I am also not sure how humans can/do/will use technology to produce those cells outside of their ‘normal’ anatomical capacity, or how that eventuality will affect the definition (if I, a biological male, can create an ovum in a testtube or an advanced 3D printer or an ovary I have implanted…).

            A philosophical/logical/computer definition of ‘binary’ only allows for two options – of the four in my preceding paragraph, but many of the readers here see a world in which 99.98% of humans are capable of producing only sperm or eggs (and I agree), and they have therefore decided that that constitutes a binary state. We are simply using two mutually exclusive definitions of ‘binary’: one is philosophically/logically ‘true’ binary,rigorously defined; the other is a loose definition of ‘binary’ close enough for most people most of the time. None of this is done out of a spirit of emotional ‘desperation’.

            I’m shutting up now, I swear. Best of luck.

          6. That’s it. No more comments here from either of you. Take it offline if you want to blather further. And remember, you said you were done here before. You weren’t. Take a week off commenting, and don’t feel you have to weigh in repeatedly on everything.

          7. The gonadal cells that make ova are irreversibly committed (differentiated) to make only ova. The gonadal cells that make spermatozoa come from a different lineage dependent on the sry gene located on the Y chromosome* and are committed to make only sperm. There is no possibility for a variant gamete that has features of both or neither because there is no progenitor cell that could make such a variant. Even the person with hermaphroditism who had sperm- and egg- producing cells in the same body did not produce spectral “ovosperm” gametes.

            Of course I did not mean that all sperm and all ova are precisely identical with no variation within each sex—meiosis sees to that. There is no sperm that looks even remotely like an ovum. But if you want to say, “Aha! Gotcha!”, go right ahead.

            In the “How do we know what we know?” department, you can ask, how do we know there are no ovosperm morphs? Two ways:
            1). The ovarian and testicular cell types are committed as above. There is no mechanism whereby an ovosperm could be produced, Even if a true hermaphrodite has an “ovotestis”, s/he doesn’t make “ovosperms”, only small sperm and large ova like everyone else of that sex. (As has been pointed out most are in fact infertile.)

            2). Well, you could say, how do we know there aren’t people out there making anatomically variant ovosperm that we just don’t know about because they feel healthy and don’t need to be investigated? If a couple has borne healthy children, we assume that their gamete-producing apparatus is working in its expected binary fashion. But if a couple is infertile or has borne children with certain types of deformities, they get investigated extensively if they wish. No case of infertility or reproductive mishap has ever been reported as due to the production by one partner of gametes that are not clearly and obviously binary. No spermatozoon that can’t swim looks at all like an egg. This is the evidence that the mechanistic argument in 1) is correct.

            I can’t believe I haven’t reached 10% yet but I’m done here anyway.
            * In people. Don’t ask me about birds, clownfish, seahorses, and parasitic worms.

    2. “Not only is Carroll a fool, but his lack of a response shows he is a coward as well.”

      Carroll is anything but a fool, and his lack of a response is almost certainly evidence of that fact.

      Sean is a careful thinker, and rather than respond by either immediately giving in or hotly defending himself, he has obviously decided to do what he (belatedly) realizes he should have done in the first place: apply his mind to the actual claims being made in that article. This will take some time to study, so he is delaying any reply.

      You could say: but Sean should have fully investigated the claims BEFORE he made his tweet. Well, yes and no. The reality is that most of us trust science and scientists–and that includes scientists themselves, when it comes to areas of science outside their specialty. And it’s perfectly legitimate to assume that scientific claims made in respected sources are accurate without independently verifying them for yourself! Which is almost certainly what Carroll did.

      As for whether Sci Am should be treated as a reliable source for scientific information, we mostly all agree that it was once true, but is not any longer. But even if Carroll is aware that Sci Am has become a source of pseudoscience in recent years, who would guess that an article published way back in 2007 couldn’t be trusted for that reason? Not me, anyway.

      1. He clearly is not a careful thinker as evidenced by his tweet. The guy knows many excellent biologists, and decided to ignore them to tweet a ludicrous diagram from a bogus publication (from 2017 I might add.) There is no care or thinking going on here.

        1. “from 2017 I might add”… That certainly makes more sense than 2007, since I didn’t think that Sci Am had jumped the shark that long ago. But that does make me less confident that Carroll was really thinking when he made his tweet.

  8. It does seem like the sex deniers are the functional equivalents of young earth creationists. Like the YECs, they don’t claim that science is wrong, rather they cherry-pick and interpret the data through an ideological lense.

  9. it only makes you want to get more approbation on Twitter, which is not a good reason for tweeting.

    Approbation is not a good reason for posting, but psychologists design social media to be psychologically emotionally addictive, to drive participation through outrage. There are no good reasons for tweeting/facebooking/etc.

    I’m not criticizing you for using those media, and I am absolutely pro-free speech (even beyond current government restrictions on speech), but I hope that all users know what they are getting themselves in for. Many users have signed over their emotional well-being to corporations amorally competing with each other to increase engagement at all costs. I don’t see a good resolution.

  10. “(I think this is the last post about binary sex for a while)”

    I understand this must get tiresome for you. But you’re one of the few scientists willing to speak up about the biological truth. I hope you continue to speak out when you come across prominent examples of these falsehoods. Your voice on this is needed.

  11. As someone posting as ThatCheeseIsMine commented on MumsNet a while ago:

    Why would all being on a sex/gender spectrum, even if we were/are (I agree gender is a spectrum), mean there is no need for categories or segregation in particular circumstances?

    Age is a continuous spectrum, and our age changes, but nonetheless we have age categories, and they are arbitrary, but they are still important. There are children’s hospital wards and children’s sports, and age limits on buying alcohol and going to nightclubs, and driving, and having sex, and so on. Because there are some situations where categories and differences matter.

    The same applies to sex. (Not gender, sex.) The sexes aren’t normally segregated for everyday activities, but they are for specific situations where being female means you are vulnerable to or different from men. Like prisons, hospital wards and sports.

    Anyone can do any gender stuff they like (masculine/feminine presentation, interests etc) and they do and have done for ages. That’s not the same thing as sex, which like age is a physical reality.

    If you think it’s so regressive to have sex categories in some situations, does the same go for age categories? No kids/youth categories for sports? No separation from adults in terms of sex, driving, voting, hospital wards etc? If not why not? It’s a spectrum.

    This ridiculous idea that if you can argue something is a “spectrum”, then anything goes, falls down at the first hurdle.

  12. I still find it hard to understand that a skeptical physicist doesn’t immediately recoil from a graphic like the one he copied out of Formerly Scientific American. The graphic is *intended* to confuse the issue. Arrows that could have been drawn straight have been crossed, boxes were duplicated to create more boxes, distances were expanded to get curved arrows in – see a bit further into Emma Hilton’s twitter thread quoted in the article, from on.

    Carroll must have noticed it. He’s a smart guy and a noted skeptic so he must be aware of quacks’ methods. Making things look more complicated than they are is such a standard trick…

  13. Amanda Montañez: “I am hopeful that raising public awareness of intersex, along with transgender and non-binary identities, will help align policies more closely with scientific reality, and by extension, social justice.”

    The “public awareness” was raised. Isn’t that enough? No, of course not.

    What exactly _is_ “public awareness” nowadays?

    And this quote by :

    Amanda Montañez: “You either have two X chromosomes or an X and a Y; ovaries or testes; a vagina or a penis.”

    I think it is telling – as PCC(E) and the readership here has discussed at length – that gametes was not in this list of objects and their counterparts. I suppose because that would have been too much for the “public” to understand.

    1. Phase 1 — list and describe Disorders in Sexual Development
      Phase 2 — ?
      Phase 3 — TWAW & TMAM!!!

      It’s the Underpants Gnome Theory of Transgender Identities.

  14. It’s self-defeating for those advocating gender as a spectrum to attempt to tie gender to biological sex. Since sex is binary, they are tying themselves to the wrong horse. Gender is a spectrum; sex is binary. Keeping the two separate is both good science *and* good for gender-rights advocates. By conflating sex and gender—whether inadvertently or on purpose—gender-rights advocates are weakening their own position. All persons deserve respect and dignity. These are not biologically contingent, and they are not advanced by an erroneous view of the nature of biological sex.

    1. It is self-defeating only if we assume that they are mistaken and otherwise operating in good faith. I have in mind those among the activist academic crowd who are intent on obliterating all stable categories so that nothing can be declared “normal”.

      I agree that they weaken their own position among those who think about these issues, but we are not the ones they seek to convert. They have other ways to deal with the likes of us! That’s probably why the ones who speak out against this publicly and most forcefully seem disproportionately retired, near retired, financially independent, or otherwise secure in their livelihoods.

  15. Dr. Coyne,

    There is no doubt that gamete sex falls in only three categories: sperm, egg, or neither.

    But sex more generally clearly fall along more dimensions. We we talk about a persons sexual orientation, we are not talking about attraction to sperm or egg. We are talking about attraction to some combination of primary and secondary and tertiary sex characteristics.

    And those primary/secondary/tertiary characteristics come in a huge variety of combinations ranging from systematically masculinized to systematically feminized to combinations of both. That makes sex more complicated once you move out of gamete size discussion.


    1. The possession of gametes of big or little size (or the biological equivalent for making them) IS the biological definition of sex. And it is binary.

      You want to redefine biological sex as something else so that you can make it into a spectrum, and I’m not going to get drawn into that morass.

    2. “or neither”

      Is that true, and why not both?

      Surely, some cases of living things’ gametes can be found to match the Boolean binary operations AND, OR, and the unary operation NOT?

      And after all that, what would it mean for H. sapiens?

    3. Yes, you are right that secondary sexual characteristics do vary a lot. So, for example, female breast size does vary a lot, and you could plot breast size on a spectrum (ditto male penis size). But a women with smaller breasts is not less of a woman. A man with a larger penis is not more of a man. You can’t put all of this together and invent a spectrum of “manliness” or “womenliness” and plot everyone on a spectrum. You still have men and you have women (excepting 0.02% DSDs)

      1. Even the 0.02% of those with DSDs are still *either* male or female. There is no additional “human” sex because the individual has a condition that affects the sexual reproductive system, any more than those with Downs Syndrome (also a congenital chromosomal medical condition as are DSDs) are a new type of “homo” genus.

    4. Sauron, why do you jump from the 100% binary gametes to the bimodal gender? Let’s not forget that the sexually relevant morphological phenotype is also >99.98% nonoverlapping. Also, as an extension of your line of reasoning, just because humans and chimps are 95% genetically the same doesn’t mean that chimps and humans don’t exist or that they are a spectrum.

    5. No. Every person – and every eutherian mammal – who has ever reproduced has done so by producing either oocytes or sperm. Those are the two reproductive roles/sexes (those who produce neither are not relevant to the definition of a reproductive method – and as pointed out below, are perturbations of either the female of male pathway). A definition of sex must work in a comparative context as all the available evidence suggests two homologous sexes in vertebrates for at a minimum of hundreds of millions of years.

      Also the two gamete types do not just differ in size, but also in motility, chromatin packaging and marking, proteins and mRNAs present, etc.

      I agree that we use secondary sex characteristics as proxies/visual cues, but that does not make sex itself “more complicated” – every species does that.

  16. At times such as these, the ideology wars wind up pitting different groups against each other in arguments about what is scientifically True. But the only way forward with such things is to have a process where if one camp is proven to be wrong, then they should cheerfully walk back what they are saying.
    The far left is clearly wrong in what has always been the meaning of the term ‘biological sex’. But do they walk back their claims that sex is a spectrum (like gender)? No. What is especially bad is that among them are actual PhDs who should know better about the process of finding consensus around what is True. I mean on one day they may find new data that disproves prior conclusions involving their own research. And they likely will learn to accept that new data and move on. But then on another day they might double-down and deny clear truths when it conflicts with an ideology about what they want to be true.

  17. All that is needed to advocate for trans rights is a commitment to individual liberalism. That’s it.

    Not quite. It depends on what’s meant by “trans rights.”

    The usual panoply of human rights — the right to a fair trial, life, freedom of movement, freedom from slavery or unjust discrimination in jobs, housing etc. — are not in dispute here. The unique right they’re claiming might be phrased as “the right to determine what your true sex is, and be believed.”

    I leave out any reference to “gender” because I’ve become convinced that’s a red herring. Every definition of gender (“social sex,” “cultural stereotypes “etc ) is inadequate for expressing or establishing what modern trans activists insist they need: the right to enter single-sex spaces and reserves as a full-fledged member of that sex, based on the way an individual self-identifies. A commitment to Individual liberalism won’t help determine this, because there’s also the individuals who object to losing the fair accommodations they’ve been granted. We’re not just dealing with one individual. The issue is therefore a scientific and philosophical one: what is sex, and does it include and primarily rest on an untestable inner conviction?

    I suspect the most important reason DSDs are thrown around is because it’s considered fair and reasonable for people who have some of the more extreme cases of DSD to choose which sex they want to live as. If transgender ppl “knowing what sex they are” and “the sex they’ve been assigned without taking that into consideration “ are in conflict, this is to be considered on par with a male zygote whose complete failure to react to testosterone has resulted in an infertile female phenotype with a vagina and a uterus. They demand the right to choose the sex they insist they know themselves to be.

    Which is not an established right, and cannot piggyback to credibility on basic human rights, DSDs, or Individual Liberalism.

    1. Suppose a trans person produces small motile gametes, has a penis, balls, and no uterus, and has all of the male secondary sex characteristics, but then wants to identify as a female. Meaning, he wants to use the women’s bathroom, be identified as a woman on his driver’s license, join the woman’s volleyball team at his college, etc…

      So someone comes along and tells him he’s really a man because, definitionally, he produces male gametes and appears to have all of the male package of reproductive organs/characteristics and zero female reproductive organs/secondary sex characteristics.

      He rejects this categorically and says that his identification as a female has nothing whatsoever to do with his physical characteristics. The fact that he produces sperm and cannot gestate is irrelevant to the question of whether or not he is a man or a woman. The fact that he “feels like a woman” is sufficient to being a woman.

      Fine, but then why do so many trans people seek to have surgery to look more like the sex they identify with?

      It is contradictory to claim “physical attributes have nothing to do with self-identification as a man or woman” and “I need to have transformative surgery to remove my male reproductive organs, pump myself with hormones, and carve out a vagina in order to look more like a woman”. If the former was true, the latter would not be necessary.

    2. A rare rare instance where I must disagree with Sastra. A male (XY) zygote that is insensitive to testosterone (because of a mutation in the testosterone-receptor gene found on the X chromosome) will not develop a uterus (or ovaries). External genitalia look typically female but the vagina (not normally the subject of attention in a healthy prepubescent girl), develops only into a blind cul-de-sac. The externally visible parts that are “default” develop as female but the internal parts that require ovary-driven Müllerian ducts do not.

      There is, of course, no reason why these girls should not continue to live as women when the cause of their not reaching menarche is figured out. No one need even ever know unless the woman decides to share.

      If I understand Sastra correctly, think she is objecting to XY trans people using the existence of these women in their own claims to be regarded as women themselves, an objection I fully share.

      1. I stand corrected, you’re probably right. I thought there might have been something slightly developed in the form of a uterus in some individuals, but it’s not, of course, a uterus.

      1. Hey, if I want to identify with the original “Romanes eunt domus“, it is equally valid.

        (And if you like that scene in Life of Brian, there is a similar scene in Québec in John Candy’s final film Canadian Bacon – only politer.)

  18. “This isn’t going to kill people, as Lysenko’s bogus “vernalization” theory did, but it still confuses and misinforms people, and infuses our field with an ideology that has spread to scientists themselves—as well as journals and granting agencies—who chill the atmosphere for free discussion. And that impedes the search for truth that is science.”

    I would argue that it is at the minimum, causing serious harm, mentally and physically. Society is being taught lies. Children are being taught lies which they unconsciously know to be lies but do not have experience and knowledge to fight – it is a cruel thing to like like that to a child.

    We do not have the stats of how many “trans” persons* have taken their lives after finding that un-necessary, needless “surgeries” and the horrific side effects from drugs that *create/induce endocrine disease* cause.

    Just one person who takes their own life because of this means this ideology IS killing people.

    And then we have the situation where a person who says they are the sex they are not, uses that as a way to access vulnerable people. To harm. The threats to life and limb are daily from people who demand that society buys in entirely to the lie.

    The lie? that humans can change sex by merely announcing it.
    That anyone who denies or challenges that lie can be threatened with impunity. That laws must be changed to ensure those who challenge – which would be you Jerry for merely publishing this – imprisoned.

    Its already happening. Women in particular, have been arrested for stating the bald fact that sex is binary and immutable. Christina Ellingsen in Norway is facing potentially three years in prison for stating this fact – because Norway have laws preventing this being stated due to it being a “hate crime”.

    People are being imprisoned. They are being harmed by the “treatments”. They are being threatened for telling the truth.

    The next level will be people being killed – whether dying from the effects of the treatments, or taking their own lives after finding out the harms that have been inflicted on them or being killed for telling the truth/challenging the ideology.

    So, this ideology MUST be fought – or we do face a totalitarian future where the truth may NOT be said and if it is, then the punishment is swift and severe.

    (* I WILL use quotes for the term “trans” as there is no such thing as a “trans person” but there are persons who, for whatever reason, “identify” as not their sex. There is a difference. The former implies an additional type of human. The latter tells the truth.)

  19. Since Jodie Foster, Lambert Wilson, and Kristin Scott Thomas are bilingual in English and French, it follows that English and French are not distinct languages, but rather positions on a spectrum. By the same logic, the polylingual abilities of Audrey Hepburn and Viggo Mortensen show that there are no such things as distinct languages at all.

    I think the “sex is a spectrum” rubbish comes from an underlying wokester bias against all distinctions between one thing and another— evident also in their hostility to school testing and grading, and in their unease with mathematics, revealed in such things as the confection of “ethnomathematics” and that Sci Am stuff about the normal distribution. Of course, this does not apply to the distinction between whites and all non-whites, where the grade of oppressor and oppressee can be awarded. But logical consistency is not to be expected in the world of fashion, including ideological fashion.

  20. Sean Carroll is human… mistakes are inevitable, he has been called and now it’s his problem not those who follow the facts.
    In the case of sex is binary, ideology can waft around, lodge itself, inconsistency, distracting, distorting, waylaying energy, time and money and the unfortunate circumstances that result.
    Lucky he is a physist not a biologist on the ground so he can move on.
    Sometime in the future the issue will settle down to a agreed state, where we live with both, sex binary, gender spectrum. Shove the zero sum aside and live with it.
    But we are human.

  21. I wonder how much if any flack biologist Sean R. Carroll is inadvertently and erroneously receiving on account of the physicist Sean B. Carroll kerfuffle.

  22. Regarding the single case of the true human hermaphrodite, is there any chance he was a chimera? Any chance the DNA of the removed ovaries could be compared to that of the rest of his body?

      1. Yes, and and also not a hermaphrodite in the sense that we use it in species where individuals can actually reproduce by producing both gamete types.

  23. I always liked this passage from Brian Pippard’s inaugural lecture as Cavendish Professor, “Reconciling Physics with Reality”.

    One conclusion to be drawn from this story is that a physics research student is apt to over-estimate his understanding of things in general. Possibly we have been brainwashing him, unconsciously of course, into the belief that, because physics is the fundamental science, therefore with his understanding of physics he is able to cope with other sciences without further education. This unconscious attitude is not confined to research students. Some years ago, while taking part in a BBC panel discussion of scientific questions asked by listeners, I saw fit to contribute my pennyworth of knowledge on some biological topic. A biologist present remarked ‘We used to have a phrase about “Old wives’ tales”; nowadays we just refer to “What every physicist knows”.’

  24. I just listened to Sean Carroll’s discussion of this minor controversy on his Mindscape podcast and the two points I took away are, I think, quite relevant
    1. His initial tweet was unnecessarily snarky and did not elevate the conversation and invited trolls
    2. While it is true that in a biological sense one can make a broad definition of sex using the size and nature of gametes, the reason that this is a topic that gets on Tucker Carlson is nothing to do with gametes but is because certain people want to attack trans people and take away their rights and will use talk of gametes as a stalking horse for other more nefarious agendas.

    For my part I think that those who genuinely want make a technical point about biological facts need to consider that they are being useful idiots for people with a fascist bent who they may not actually agree with.

    1. I think we do (and this area has taught me a lot), for example the video points out how this issue is based on and promotes bad science education. If it is vital for science and education it shouldn’t be a worry anymore than pointing out that in a Milky Way coordinate frame Earth is spiraling and not elliptically orbiting Sun would be useful idiots for flat earth people with a pseudoscience bent.

      Wouldn’t the opposite argument be that better biology would both work against the fascist bent ideas as well promote Wright’s note that other interest groups agendas becomes less fragile by not compromising it with erroneous science?

      1. I agree that pointing out biological reality does not mean aligning with fascists/right-wingers Indeed, there are many left-leaning women (& some men) who oppose this ideology. Trans-activists seek to are attempting to attack our understanding of two discrete sexes to further their argument that gender identity is more important than sex. This latter notion is a demonstrably false idea – women and girls worldwide are oppressed on the basis of their sex, not gender identity. This is why female only spaces, activities and representation (which activists are trying to eliminate) are important.

        The right in the US are targeting trans-ideology not just out of phobia but because it’s an easy target due to the illogical, misogynistic, regressive, and homophobic things some prominent trans-activists proclaim (e.g. TW are W, sex is a spectrum, gender ID trumps sex, lesbians must date TW or are transphobic, sex is a social construct/invention of the patriarchy, conflating disorders of sexual development with gender identity, etc.).

        Frankly, the reason more left-leaning folks don’t speak out (except in anonymous forums – e.g. NYT columns that pertain to these issues, see the comments in is fear.
        Posts like the one by Tony Eales above add to this, and are reliant on what’s colloquially known as the “Hitler was a vegetarian” argument. I commend Jerry Coyne for speaking out on this.

        Another of the falsehoods some activists push is that people can change sex, which particularly hurts those who suffer from dysphoria. This being an evolution forum, I feel obligated to point out that no subset of males will never be thought of as females, regardless of much that speech is socially enforced. The reason why should be obvious (Hint: it rhymes with election).

        Finally, homophobia can lead to some right wing folks be “pro-trans” ( AKA “transing the gay away). This is the case in Iran, where being gay is taboo, but being trans is not. The mom of the one of the kids brought before the Texas legislature to argue for “gender affirming health-care” was caught on tape admitting she didn’t want a gays son.

        1. I take the point that the ideology being promoted by some trans activists is anti science and frankly wrong. The good thing about scientific facts is that they were true before the current culture war fads and will remain true once the culture war moves on to the next thing.
          Given this I have to ask myself the classic three questions

          Does this need to be said?
          Does this need to be said by me?
          Does this need to be said by me now?

          In answering these questions I personally need to weigh the harms and benefits of speaking up. I think it’s not quite right to characterise all the silence on the left as stemming from fear. YMMV

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