Once again, the binary nature of biological sex: Colin Wright and Sean Carroll

December 6, 2022 • 9:30 am

I don’t want to write much more about this issue, but since we’ve been discussing the binary nature of human sex (or non-binary, if you oppose that view), I thought I’d call to your attention two items.

The first is a piece by a strong defender of the sex binary, Colin Wright, in which he republishes his first article on the topic (Quillette, 2018), and updates it. The second is physicist Sean Carroll’s new video discussing and explaining his controversial tweet implying that sex is not binary, but a spectrum. We’ll take them in order.

The new piece by Colin Wright at his Substack site (Reality’s Last Stand) is really the republication of his 2018 Quillette paper (“The new evolution deniers“), with an introduction to cover the last four years. Wright was on the track to be an academic at the time, but the Quillette article, which received a bunch of pushback, combined with other articles he wrote, including an op-ed with Emma Hilton in the Wall Street Journal, made him un-hireable and so he had to leave academia. He more or less predicts that at the end of his 2018 paper.

Colin’s first article is about the binary nature of sex and about those who deny it for ideological reasons.  As you know, I agree with Wright that sex is effectively a binary, or at least with this statement that he made in that article:

. . . the final result of sex development in humans are unambiguously male or female over 99.98 percent of the time. Thus, the claim that “2 sexes is overly simplistic” is misleading, because intersex conditions correspond to less than 0.02 percent of all births, and intersex people are not a third sex. Intersex is simply a catch-all category for sex ambiguity and/or a mismatch between sex genotype and phenotype, regardless of its etiology. Furthermore, the claim that “sex is a spectrum” is also misleading, as a spectrum implies a continuous distribution, and maybe even an amodal one (one in which no specific outcome is more likely than others). Biological sex in humans, however, is clear-cut over 99.98 percent of the time. Lastly, the claim that classifying people’s sex based on anatomy and genetics “has no basis in science” has itself no basis in reality, as any method exhibiting a predictive accuracy of over 99.98 percent would place it among the most precise methods in all the life sciences. We revise medical care practices and change world economic plans on far lower confidence than that.

If you haven’t read the Quillette piece, you can do so as it’s embedded in the update below; click to read

Wright recounts the genesis of his article, which was his realization that the binary nature of biological sex was under attack, and that, like creationism, this was a denial of scientific fact, though coming from the Left rather than the Right. He argues in the update above that he was motivated only by a concern for biological truth and not to attack “gender ideology”:

One thing you may notice is that The New Evolution Deniers doesn’t mention gender ideology at all. That’s because I came to the gender debate believing that people were simply wrong about biology, and that if I could clearly articulate exactly why, I would change people’s minds. It wasn’t until later, after looking under the hood to see where modern sex denialism was coming from, that I realized this wasn’t a matter of ignorance, but a result of highly motivated reasoning. It wasn’t about true or false to them, it was about good versus evil.

Although I’m on Colin’s side vis-à-vis the biological facts, as well as about the ideological nature of opposition, in fact if he doesn’t “mention gender ideology in the original piece”, he certainly alludes to it very heavily. For example:

Even more recently, the most prestigious scientific journal in the world, Nature, published an editorial claiming that classifying people’s sex “on the basis of anatomy or genetics should be abandoned” and “has no basis in science” and that “the research and medical community now sees sex as more complex than male and female.” In the Nature article, the motive is stated clearly enough: acknowledging the reality of biological sex will “undermine efforts to reduce discrimination against transgender people and those who do not fall into the binary categories of male or female.” But while there is evidence for the fluidity of sex in many organisms, this is simply not the case in humans. We can acknowledge the existence of very rare cases in humans where sex is ambiguous, but this does not negate the reality that sex in humans is functionally binary. These editorials are nothing more than a form of politically motivated, scientific sophistry.

. . . Despite the unquestionable reality of biological sex in humans, social justice and trans activists continue to push this belief, and respond with outrage when challenged. Pointing out any of the above facts is now considered synonymous with transphobia. The massive social media website Twitter—the central hub for cultural discourse and debate—is now actively banning users for stating true facts about basic human biology. And biologists like myself often sit quietly, afraid to defend our own field out of fear that our decade of education followed by continued research, job searches, and the quest for tenure might be made obsolete overnight if the mob decides to target one of us for speaking up. Because of this, our objections take place almost entirely between one another in private whisper networks, despite the fact that a majority of biologists are extremely troubled by these attacks to our field by social justice activists. This is an untenable situation.

If that’s not mentioning gender ideology, I don’t know what is! It’s hard to believe that someone could write about the controversy without mentioning why it exists, and Colin certainly does that.  I don’t see an issue with his take on why the controversy arose—and I agree that it’s a dispute over ideology, not biological fact. But I do take issue with his new claim that he doesn’t mention gender ideology.  Still, that’s really a quibble. The fact is that although Wright has left academia, he’s still fighting to make people realize the biological facts about sex, but is now also fighting ideologues who claim that he’s a transphobe.

He’s not. If you read his original piece in Quillette, you will find this:

It is undoubtedly true that trans people lead very difficult lives, which are only made more difficult by the bigotry of others. But social justice activists appear completely unwilling or unable to distinguish between people who criticize their ideology and people who question their humanity. Their social immune system appears so sensitive that it consumes itself. We need to acknowledge that trans issues and ideology are complex, and concern one of the most marginalized communities in the world. Because of this, we must give these issues the respect they deserve by approaching them with nuance and compassion instead of crudeness and cruelty. But we must not jettison truth in this process. If social justice activists require scientists to reject evolution and the reality of biological sex to be considered good allies, then we can never be good allies.

I would add in the first sentence “unwilling or unable to distinguish between people who criticize their ideology and people who question their humanity and the facts of biology.”

So much for Dr. Wright, who describes the biological fact accurately.  Now onto Sean Carroll, who started a mini-fracas on Twitter when he made the tweet below, criticizing Wright’s correct claim that “biological sex is real, immutable, and binary”, and then putting up a misleading graph from Scientific American implying that biological sex is a spectrum. The figure even shows a spectrum of colors. It isn’t rocket science to see that Sean appeared to agree with the Scientific American stand.

I tweeted back defending the same biological issues that concerned Wright.

And several other people, including responders to Sean’s Tweet, as well as Wright, Steven Knight, and Manchester Uni biologist Emma Hilton, criticized Sean’s view as well (see my post about that here).  Sean has responded on a video from his Mindscape series, and in the interest of fairness I’ll present his discussion of sex and of the tweet above. You can hear the discussion at the beginning of the podcast below. The bit about sex, the binary, and the tweet go from 05:29 to 25:30. 

To his credit, Sean begins by apologizing for that tweet, which he says was “snarky, dismissive, and lowers the tone of the debate.” You have to admire him for that—how many people would admit it and apologize?

He then elaborates on what his tweet was trying to say, which boils down to the idea that “human sexuality is complicated.” There’s a complicated developmental pathway that yields gametes and other traits associated with sex, chromosomes play a role, and there are other “secondary sexual characteristics”, like voice timbre and body hair, associated with sex. Further, he notes that “there are psychological, sociological, cultural and political aspects of sex,” which includes gender, your rights, how you’re treated by others, and so on. He says that there are issues beyond the biological ones, including philosophical and language issues, and he expatiates on those issues, evincing—and I agree—an empathy for those who are neither biologically male or female, as well as transsexual people.

I won’t go into that, for you can listen for yourself. All I’ll say is what I was trying to say in the first place: biologically speaking, sex is as close to a binary as you can get. And yes, like all developmental processes, it’s complicated. The sex binary is opposed or even denied by a lot of people, but the denial is largely motivated by ideology. The dispute does not come from a quarrel among biologists.

I’ll add as Sean emphasizes, that we often use “sex” in a looser manner, since we can’t see people’s gametes. That’s the difference between defining sex and recognizing it. Things become messier when you try to define sex using traits, like genitalia, that some people use to recognize sex.

Finally, of course I agree with Sean that “we should give all human beings equal dignity”. I believe I’ve made that point repeatedly when I write about the sex binary. I care more about the binary than he does simply because I am a biologist, because this issue involves evolution, and because I care about whether the facts of biology are presented accurately to people. Finally, I care that that biology remains, as far as humanly possible, free from intrusion by ideology.

65 thoughts on “Once again, the binary nature of biological sex: Colin Wright and Sean Carroll

  1. Nice. Sean Carroll is an admirable thinker, and I admire his willingness to apologize and clarify what he meant.

    I imagine Sean Carroll would probably take a similar hard-nosed and precise tack as PCC(E) regarding people misunderstanding the so-called “measurement problem” of quantum mechanics as indicating that the human mind is essential to the progression of external, cosmic reality.

    There are actual facts of science, and they are not subject to popular vote. Reality is whatever it is, whether anyone believes in it or not…even when there’s no one around TO believe in it.

  2. A great article, thanks!

    Robert put it better than I can: There are actual facts of science, and they are not subject to popular vote. Reality is whatever it is, whether anyone believes in it or not…even when there’s no one around TO believe in it.

  3. The binary nature of biological sex is true for vertebrates and most invertebrates and plants, but “sexuality” (“genetic pairing/mating”?) can sometimes be more exotic for fungi and bacteria. Perhaps those defending that there are more than 2 biological sex should specify which biological Domain they are alluding to.

    1. It seems important to differentiate between sexes and mating types:

      “The categories of sexes (anisogamous gametes) and mating types (gametes with genetic incompatibility markers) need to be kept apart because some species have both.”

      (Griffiths, Paul. E. “What are Biological Sexes?” Preprint, 2021. p. 11)

      “A sex is thus an adult phenotype defined in terms of the size of (haploid) gamete it produces: in an anisogamous population, males produce microgametes and females produce macrogametes. A simultaneous hermaphrodite is thus both male and female simultaneously, and a sequential hermaphrodite transforms sequentially from male to female (or vice versa). This definition of a sex differs from one that defines a sex in terms of gamete mating types (…). Under the Parker et al. definition of a sex in terms of gamete size, a mating type is not considered to be a sex, but simply a gametic type (that may or may not be related to gamete size) that shows a preference for fusion with certain other gamete types. In isogamous populations, there is thus one sex (though there may be several mating types). Retaining the definition of a sex for an adult phenotype that produces a given gamete size, and a mating type for a gamete phenotype that has a given characteristic for selective fusion may serve to remove some of the confusions that have arisen in the literature.”

      (Parker, Geoff A. “The Origin and Maintenance of Two Sexes (Anisogamy), and Their Gamete Sizes by Gamete Competition.” In The Evolution of Anisogamy: A Fundamental Phenomenon Underlying Sexual Selection, edited by Tatsuya Togashi and Paul Alan Cox, 17-74. Cambridge: Cambridge University Press, 2011. p. 18)

  4. Carroll says “There’s a complicated developmental pathway that yields gametes and other traits associated with sex, chromosomes play a role, and there are other “secondary sexual characteristics”, like voice timbre and body hair, associated with sex.”
    This is true. We have been very occupied with discussing the sex binary that we have not discussed these developmental pathways sufficiently. Here is an article that discusses how to think of the pathway between sex and sexual development: https://darwinianreactionary.wordpress.com/2019/10/22/normal-sexuality/

  5. What about mitochondria? Aren’t they almost always inherited from the female because the spermatozoa have only a small contingent? Mitochondrial Eve, and that? How does that play into the discussion of male or female?

    1. Only that maternal mitochondrial DNA is passed on into both sexes, while paternal mitochondrial DNA effectively does not. Mitochondria otherwise has nothing to do with biological male versus female.

  6. I should add that I’m at work and haven’t the time to read the articles yet, but the mitochondria question had been bugging me and hadn’t heard it addressed yet, or missed it. And no, I’m not a scientist, nor do I play one on tv, so ignore me if my questions are so dumb to not be worth discussing.

    1. No it’s not dumb! Mitochondrial inheritance is another one of those secondary sex traits that differ between males and females. But it’s not part of the definition of the two sexes (based on gametes) or part of how one distinguishes male vs. female individuals (because it’s so hard to observe directly).

      1. I guess my question is do the refuseniks reject the idea that mitochondria only get passed down from the mother, meaning that they would claim that someone who is “gender fluid” or trans could claim that by declaring themselves female that their personal mitochondria could be passed down to an offspring. I realize it’s not a practical test, it was just something that I was thinking about over my PB&J lunch.

        1. I suspect they don’t get as far as rejecting it, as they don’t even consider it, or in many cases, know about it.
          Presumably, if told about it, these gender theorists would tell you that you are a lying ‘phobe and cancel you. Just like gametes – don’t matter! Chromosomes? – Don’t matter! Endocrinology? – Doesn’t matter! It seems that sexes did not develop to allow a certain form of reproduction with added mix-and-match genetic variation, but simply as a tool of the patriarchy to divide and conquer. I’m still waiting for the historical evidence of matriarchal societies that did not have sexes, but it must be coming any day now.

  7. > I agree with Sean that “we should give all human beings equal dignity”

    I don’t. I don’t think we should give human fetuses or human corpses the same dignity as living humans who have already been born. I also think that there are also living humans where it might be worth discussing what kind of dignity they deserve, particularly those in a permanent vegetative state.

      1. Great article, thank you!

        [D]ignity has three features that undermine any possibility of using it as a foundation for bioethics. […] dignity is relative […] dignity is fungible [… and] dignity can be harmful […] A free society disempowers the state from enforcing a conception of dignity on its citizens.

  8. If sex is a spectrum, show me the spectrum of gametes. I see the spectrum of peoples ‘genderly feelz’ so I accept a gender spectrum, but show me the rainbow of gametes.

    1. The goal of establishing that sex is a “spectrum” is, I think, twofold:

      1.) eliminate sex as a reasonably clear method of differentiating men from women while leaving space in the middle for people who claim to be neither. This requires deference to Gender Identity as the best measure.

      2.) support the idea that males who take female hormones & undergo feminization surgery are now much closer physically to the female end of the spectrum than they are to other males (and same for females undergoing the process of “masculinization “), and should be grouped accordingly.

  9. For example, here’s a paper by Claire Ainsworth titled “Sex Redefined” (2015), which has recently been mentioned by German gender activists as an alleged scientific confirmation of their assertion that there are more than two sexes: https://www.nature.com/articles/518288a

    There is a table titled “The Sex Spectrum”, but what I see there is not really a spectrum of sexes but just a spectrum of chromosomal and phenotypical variants that do not constitute additional sexes—especially as biologists do not define sex in terms of chromosomes or/and phenotypes.

    Ainsworth shouldn’t have used the highly misleading title “The Sex Spectrum”, because she herself doesn’t mean to say that there are actually more than two sexes.
    When asked on Twitter “In your piece ‘Sex Redefined’ are you making the claim there are more than 2 sexes?”, Ainsworth replied: “No, not all. Two sexes, with a continuum of variation in anatomy/physiology.”

    An important general point is that…

    “The chromosomal and phenotypic ‘definitions’ of biological sex that are contested in philosophical discussions of sex are actually operational definitions which track gametic sex more or less effectively in some species or group of species. Neither ‘definition’ can be stated for species in general except by defining them in terms of gametic sex.”

    (Griffiths, Paul E. “What are Biological Sexes?” Preprint, 2021. p. 1)

    “To a biologist, “male” means making small gametes, and “female” means making large gametes. Period! By definition, the smaller of the two gametes is called a sperm, and the larger an egg. Beyond gamete size, biologists don’t recognize any other universal difference between male and female. Of course, indirect markers of gamete size may exist in some species. In mammals, males usually have a Y chromosome. But whether an individual is male or not comes down to making sperm, and the males in some mammalian species don’t have a Y chromosome. Moreover, in birds, reptiles, and amphibians, the Y chromosome doesn’t occur. However, the gamete-size definition is general and works throughout the plant and animal kingdoms.”

    (Roughgarden, Joan. Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. Berkeley: University of California Press, 2004. pp. 23-4)

    1. “…Ainsworth replied: “No, not all. Two sexes, with a continuum of variation in anatomy/physiology.”

      Sorry, there is a word missing. She writes: “No, not at all.”

  10. I’m glad Mr. Wright weighed in on this. I’ve sent him (a tiny amount of) Money.
    Like our host he is a voice of sanity in the madness.

    Sean (and others) are good examples of experts in their field making claims they’re really not as good as even well informed amateurs in.
    There are topics I know a Lot about from years of study, qualifications, deep reading over decades or experience. Other areas I avoid in my column or dinner parties. Or I hedge big time.

    I pride myself on epistemic humility and I wish more big shots did also.

  11. The use of “trans” shortened unfortunately from “trans-sexual” (like now the prefix has become corrupted) seems inherently to support the binary itself. Generally it means going from one to another, though can have more subtle meanings. Rather than destroying the language, like “phobia” in Islamophobia, I wish there would be more care in creating firebrand words.

    1. Concur. It’s not just in English, either. In German, the adjective ‘diverse’ has been entirely repurposed to mean ‘non-binary’. That means that calling a group ‘diverse’ no longer means that it has people with a variety of backgrounds. That’s probably the single most painful development I’ve seen in the last few years – but I fully expect stranger abuses of language to befall us.

      1. Not really. There was a court ruling allowing true intersex people to specify “divers” rather than male or female. There was some debate on which catch-all term is best. In that sense, yes, “divers” means “intersex”, which applies to a small minority of people. Nothing to do with trans and so on. Outside that context, “divers” hasn’t changed its meaning.

        1. We’ve had the discussion here that groups can be diverse (with people from various backgrounds) while individuals can be divergent (diverging from the mainstream, if it exists). I wouldn’t object to the existing term ‘intersex’ but might prefer ‘sexually atypical’ or ‘sexually exceptional’ (as in ‘an exception to the 99.98%’; unfortunately, ‘exceptional’ has various polarizing definitions in English, with some people only using it as an ultra-high and others using it as an ultra-low, viz. ‘exceptional learner’).

  12. Given the gametic definition of sex, individuals who are classified as intersexual but can nonetheless produce either ova or spermia are either female or male, no matter how chromosomally or phenotypically abnormal or atypical they are. Right?
    But what about intersexual individuals who can produce neither ova nor spermia? They are sexless (neither female nor male) under the gametic definition, aren’t they? Or does this definition allow one to classify even them (some of them at least) as either female (quasi-female) or male (quasi-male) in a non-arbitrary way?

    1. Perhaps but it is only a variation on the two sexes. A developmental disorder. “Disorder” says it all.
      If any of these people could reproduce consistently others of that type maybe that would be another sex but that doesn’t happen.
      If they could reproduce it would be in line with the sex binary.

    2. First question: Yes. But the person may not necessarily be willing or able to have the medical investigations needed to figure out unambiguously which type of gametes he or she is able to produce. So while all are undoubtedly male, female, or both (as in rare people with ovotestes who make both gametes), it may not be possible in the individual person to say for sure especially if resources are limited. Most children who don’t have a recognizable penis will want to be raised in childhood as girls to avoid teasing in boys’ locker rooms. At puberty there may be some surprises. If it turns out then that he has testes that could produce gametes and testosterone he will be a male. A male without a penis who has been raised as a girl may not feel like a male but if he was interested in having children, he would have to accept that he would be contributing sperm (somehow), not eggs. He is reproductively male and needs to find a female partner.

      Second question: People who produce no gametes, never could, and never will, because they have no gonads are sexless by our definition. However, people with complete gonadal agenesis will look like normal baby girls (regardless of presence or absence of a Y chromosome) and there will be nothing to suspect anything wrong until menstruation doesn’t start. They don’t identify as intersex. Since they were instantly recognized as girls in the delivery room and were registered as female births, they are entitled to continue to call themselves girls/women. Even if they are found to have a Y chromosome, this doesn’t make them boys either in a reproductive sense (because no gonads, no sex) or in a social presentation sense. No one would refer to such a girl as “mis-assigned female at birth” and tell her to make her body muscular and hairy with testosterone to have it match her Y chromosome. She might want to take estrogen to prevent osteoporosis, though.

      I need to stress how unhelpful it generally is to patients to be told what they “really” are if it’s different from how they have been brought up. We need to see patients as individuals with needs, not to satisfy ourselves that our classification system is air tight. The main thing is that none of these so-called intersex conditions undermine the central idea that sex is an absolutely dichotomous character. There are no intermediate or spectral gametes, ever. There are all sorts of anatomical and functional differences, though, which socially are the basis of what we think of when we think of sex, and some of them will be different enough to be a burden to people affected. But these are all developmental abnormalities, like having a cleft palate obvious at birth or some forms of heart disease that don’t show up until adulthood. They don’t represent a spectrum of normal development.

  13. I think Sean got the following part especially right, I think. From 12:45 to about 16:00:

    [The gamete-production definition of sex is] a term of art in biology. It does make for a weird dating profile: if you say, I’m 5’10”, 28 years old, sandy blond hair, small motile gametes. Nobody ever says that, right? Why not; what is the point of bringing this up? Well, somehow, for hundreds and thousands of years, human beings have been able to have this concept of human sexuality, without knowing anything about the size of their gametes.

    You could choose to be clear, if really what you mean is [this definition]: … [then say:] “Human beings either have large sessile gametes or small mobile gametes.” And guess what, no one would argue with you … . The reason people go on and translate that into “biological sex is real and immutable and binary,” in a way that doesn’t make clear that they are referring to this term of art within the context of biology, is precisely because they want to claim more than that. Because I agree with Jerry Coyne very much [about the fallacious appeal to nature] … . Why would people get invited onto the Tucker Carlson show to talk about the size of gametes? … It is precisely because they want to cheat. They want to equivocate between the biological definition and the human-scale definitions. They want to use the language and deploy it in such a way that you can say, sex is only binary, therefore, we should not believe that transwomen are women, for example.

    1. I disagree – he gets this wrong. The definition of sexes based on gamete size is not a term of art. It’s a universal definition for all animals. Humans are animals. In some animals it’s possible to see the gametes by picking up the animal and looking at it, and there’s no guessing which is female and which is male. It happens that in humans this isn’t possible (the body wall is opaque, the gonads are internal), but that doesn’t mean humans don’t conform to the same definition of the sexes.

      The urge to use secondary sex traits to define the sexes arises because a tiny minority of individuals who are one sex want to be able to say they belong to the other sex. This is indeed a term of art that involves behavioral or medical or surgical modification of some of those secondary sex traits. It’s also a kind of denial of evolution — denial of the continuity of animal life from sponges to humans — as Colin Wright correctly described it.

      1. I disagree in turn. People who are not wearing their biologist hat generally define sex by phenotype. When was the last time you looked at an attractive person and thought, “OOoo, nice gametes!” Of course the biological definition applies to all animals (and many plants); that’s why science honed in on it. But the goals of science and of daily life, while they overlap, are different.

    2. The only time human-scale definitions of “woman” don’t track with the biological-scale definition of “woman” is when a culture has such rigid sex roles that a man who violates them is scornfully called a woman in derision, or something that’s not a man in bewilderment.

      There’s equivocation and cheating going on, all right. But I don’t think it’s coming from the side that defines a woman as the female of the human species. It appears to be coming from the side that defines a woman as I don’t owe you a definition, transphobe.

  14. Call this a nitpick, but the language and notion of “non binary” of anything still strikes me as specious.

    Left/right handedness is binary. Ambidextrosity means neither 100% left nor 100% right, but that does not mean handedness is “non binary”, nor that an ambidextrous person exhibits “non binary handedness” – they are ambidextrous. That is very clear language for a very clear idea.

    Ambidextrousity is also not “non ternary”, nor “non unary”, but do all the “non-this and “non-that” sound sensible? No, because ambidextrosity does not negate binary handedness.

  15. The problem with Sean Carroll is his moral certainty:
    “ I care a huge amount about whether we treat human beings with dignity and respect, including people who are intersex, including people who are trans. I think that in the world we live in, we do not do that right now. These people suffer, they are subject to depression and suicide and bullying. And it’s an embarrassment, it’s something that as a culture, we should be embarrassed about. It’s one of the very clear ways in which we fall short of giving all human beings equal dignity, right?”

    There are a lot of moral problems with things like “affirmative care” or puberty blockers.

    1. “… they are subject to depression and suicide and bullying. ”

      Abigail Shrier discusses the notion that suicide and gender problems are connected in Irreversible Damage but I do not have quotes handy. I need to get it again.

    2. Don’t mean to overcomment but I agree with you about these moral problems. First, people with DSDs don’t want to be called “intersex” because they are not between the two sexes. These people are males or females, and don’t want to be lumped in with AGPs and other people who are trans (whatever that means).

      Second, it’s not at all clear that being trans is the cause of depression, suicide, and bullying due to others “fall[ing] short of giving all human beings equal dignity.” It’s not even clear that trans people have higher rates of suicide than other people with similar mental health problems who are not trans.

      Instead it’s likely that autism and other psychiatric disorders (which are highly heritable, have many known genetic risk factors, and are wildly over-represented among youth treated in gender clinics) lead to depression, gender dysphoria, and the feeling of being trans. Lots of people with autism, psychosis, and other mental health issues do experience depression and discrimination (it practically goes with the territory for people with bipolar disorder or schizophrenia). That’s bigotry but it’s not transphobia.

  16. Scientific claims, like non-binary sex, made contrary to evidence, remind me of the 1984 practice of forcing citizens to accept that 2 + 2 = 5. This strikes me as a means of asserting power rather than reason, just like Trump’s lies- if you an make people believe an assertion contrary to reason and the evidence of their own eyes, you have power over them. Indeed, one of the main objectives of “critical theory” is to make science and reason the enemy of the people, like Emmanuel Goldstein in 1984. The actions of the DEI thought police only makes the parallel more evident.

  17. I like Sean Carroll’s books on physics and have learned a lot from them. He is truly in command of his material and easily instructs even non-physicists like myself. Having said that, I’m afraid he’s stepped off a cliff regarding sex as non-binary. His intentions and sentiments are good, but intentions and sentiments are not science.

  18. Here is a statement of fact. ‘Apart from fungi and some kinds of algae, multicellular organisms are anisogamous. Individuals within anisogamous species produce either large or small gametes. Humans are multicellular anisogamous creatures and are therefore strictly binary when they are capable of gamete production.’

    So here’s my question. Why do biologists need the words male, female and sex to discuss the exchange of genetic material through small and large gametes? Beyond gamete size what does a ‘male’ plant have in common with a ‘male’ vertebrate? Why not call them minigamous and the ‘females’ maxigamous?

    Knowing an individual’s type of gamete production without knowing its species tells you very little about its phenotype or behaviour. Sean Carroll is incorrect when he says that biologists use male and female as terms of art. They are terms of tradition and convenience. Saying that sex is binary because gametes are binary is an ideological statement. At minimum it is buying into the notion that scientists have the authority to define what words mean despite history and common usage. But, generally, the statement is used to deny the identity and even existence of people who don’t fit or don’t feel they fit the traditional categories of male and female.

    1. “Saying that sex is binary […] is used to deny the identity and even existence of people who don’t fit or don’t feel they fit the traditional categories of male and female.”

      I assume the “statement” above is accurately re-stated in quote form.

      So now I ask about how “tradition” is working here. What “tradition”? Where is this “tradition” from, how would we know it?

      Otherwise – I fail to understand what the point is.

      1. Sorry I was unclear. The statement I am referring to at the end is the statement that ‘sex is binary because gametes are binary’ – not a direct quote, but said in many ways on this site and others.

        Luana Marjora:

        “One of the most fundamental rules of biology from plants to humans is that the sexes are defined by the size of their gametes—that is, their reproductive cells. Large gametes occur in females; small gametes in males. In humans, an egg is 10 million times bigger than a sperm. There is zero overlap. It is a full binary.“

        What I am saying is that though this is true – using the words male and female in this context loads a lot of other assumptions and ideology. Though there is zero overlap in gamete production, there is a lot of overlap and ambiguity in what we consider ‘male’ and ‘female’ when we consider behaviour and phenotype, which is the traditional way of determining male and female right up to the late 19th century when the idea of gametes was defined and named.

        1. People in the past did not determine who was a male and who was a female by looking at their behavior. They looked at males and females and determined how they ought to behave considering this.

        2. “… there is a lot of overlap and ambiguity in what we consider ‘male’ and ‘female’ when we consider behaviour and phenotype …”

          My previous comment was a request – and I still haven’t seen any examples of “what we consider ‘male’ and ‘female””, how much exactly these things “overlap”,… or is it “ambiguity”…

          Perhaps elbows count. Are male elbows really much different from female?
          Vein structure?
          Digestive enzymes?

          These things sound like phenotypes (enzymes) or behavior (handedness), they overlap between male and female to me. Are they part of the point being made?

          1. As always, I echo Sastra above.

            > “Perhaps elbows count. Are male elbows really much different from female?”

            (I am taking this as a serious question and this is a serious answer.)

            Getting warm. Some men who present as women after going through male puberty can be nonetheless quite convincing with hormones, hair, makeup, voice, and mannerisms, especially if they add body sculpting. (My nephew-in-law got taken in during a first “coffee date”. He’s a good soul, if not the sharpest tack in the pizza, and gently laughed it off as he told the story to family.) I mean not just breast implants but lip injections and surgical shaving of the Adam’s apple and the brow ridge that keeps the water in the shower from running into our (male) eyes. But the male mandible is heavier, the hands are different — you can see this even in the videos influencers post on YouTube when they talk with their hands –, and the distal end of the forearm bones (colloquially called the wrist but it’s still the forearm) and the bones of the leg at the ankle joint. And the feet are always bigger, even in a short man. All the bones are bigger and heavier, even the elbows, but the ones I listed are the ones you can see easily. Women have a different “carrying angle”, on average, when standing with the palms forward, and yes, this difference arises in the two joints at each elbow.

            All these features, which are just the easily visible surface anatomy never mind the bones of the pelvis, kill the illusion that the person is a woman pretty quickly. Once you see them and integrate them all, you know he’s a guy. You can’t unsee it. It’s like finding the penguin (“Leif Penguinsson”) in the Nature Briefing quiz on Fridays. So taken in total, I doubt there is much overlap between male and female bodies, even drugged and surgerized. Women can masculinize to some degree beyond body hair but men can’t really feminize, (which is why they shouldn’t compete as women.)

            And if you are really stuck in trying to distinguish a male phenotype from a female, you can go by the presence of a penis and scrotum. That usually works. They will shrink some after years of testosterone deprivation but they don’t disappear. Fortunately few men seem to go in for “sex-change” surgery any more because bottom surgery doesn’t work very well. Today they don’t need a sex change, they just need a gender change.

            There is a growing genre now of trans pornography. I’m not sure who the paying customers are for this but it is useful for casual research into phenotypic mimicry albeit with highly biased samples.

            1. OK – apparently “handedness” is .. well, they’re working on it :

              “The distribution of hand preference in normal men and women”

              “Male-female differences in left-handedness in Sardinia, Italy”

              … though I never read about transgender patients interested in changing their hand preference. I just assumed stochastic events explain how most people are right-handed. And maybe kitchen layout.

            2. [ just one more I hope, I’ll try to lay off after this ]

              baldness genes – I’d have to review this area, but I think men get them more frequently than women – perhaps a Punnett square will show how.

              Yet, I have not seen any interest of females incorporating this trait in their bodily transformation to male. Why not? It would be expected, if I understand – or it would be excepted – if so, why?

              Males, though – remember Hair Club for Men? Clearly males will pay to counteract baldness genes. Not that there’s anything wrong with that!

    2. “Saying that sex is binary because gametes are binary is an ideological statement.”

      I disagree. Because gametes in the plant and animal kingdom fall into discrete size categories, it becomes an empirical description of nature’s reality to then define sex in this way and conclude it is a binary pattern. There needs to be general agreement on what words like sex mean in order to have a productive discussion about the many issues related to sex that include reproduction, development, population genetics, evolution, behavior, etc. Focusing solely on humans and human expression is fine of course, if the topic is about human sexuality, gender expression, and the like. But from what I’ve seen from gender activists in the media and even in my place of employment is an effort to conflate/confuse two different ideas (sex and gender) and then assert that sex is a continuum. This is an assertion without evidence. Indeed, all of the evidence indicates otherwise, in humans as well as the millions of other anisogamous species on the planet.

      I’m an advocate for clarity in what our words mean. Otherwise, what’s the point of trying to communicate? None of this should be taken as denying anyone’s identity or existence. Indeed, I have nothing but compassion for those who feel like they don’t belong in traditional categories. I’d like to think that the general awareness campaigns of human sexuality, orientation, and gender expression issues have helped to reduce bigotry and increase social acceptance, but perhaps I’m wrong on this. Redefining basic biological concepts in an effort to advance a social justice cause strikes me as wrongheaded.

      1. Exactly. Let’s be clear about what our words mean in our attempt to communicate. Defining sex differences in a reproductive biological context definitely needs to refer to gamete size. But I must disagree that making the statement that gamete size determines sex in the context of the complications of defining gender and sexuality in humans is not overlaid with ideology (and it certainly feeds into the ideology of those who would deny the lived reality of a large number of people.)

        Renaming is not redefining. We can talk about gamete size and its effects on reproductive evolution without using the words male and female. Or we can, as we seem to be doing, reserve male and female for medical or biological contexts and use different words when we are talking about appearance and behaviour. Or we can define, as narrowly as possible, the context in which we are using the traditional words.

    3. Denying the biological differences between men and women have serious detrimental consequences for women -in sports, or prisons, for example-, and teenagers -who are denied proper counselling and care. It’s at least as bad as transphobia.

    4. “a lot overlap and ambiguity in what we consider ‘male’ and ‘female’ when we consider behaviour and phenotype,”

      How much, how significant, and examples are necessary.

      “… which is the traditional way of determining male and female right up to the late 19th century when the idea of gametes was defined and named.”

      What precisely does this mean, and what is the relevance of – a peculiar word for this – “tradition”?

      Knowledge is superseded when better science produces better knowledge, but I do not see how that makes the antiquated knowledge a “tradition”.

    5. I’m going to bet that the terms male, female, man, woman, etc., date back to long before the existence of gametes or fertilization was known. Sure the critter with the penis was doing something to the one with the vagina that sometimes resulted in eggs or babies, but exactly what was a mystery until microscopes were invented. And the ovum was discovered only much later, up to which time it was believed that the man planted his seed in the furrow of the woman’s soil and up grew a baby, like a carrot.

    6. “Let’s be clear about what our words mean in our attempt to communicate.” By all means.

      But somehow “[reserving] male and female for medical or biological contexts…[denies] the lived reality of a large number of people.”

      Says the person commenting on the web site of a biologist.

      This relentless policing and appropriation of language is (at least to this other biologist) intolerable and unacceptable.

      Chairephon, “male” and “female” are taken. Biologists use them to mean a specific thing. You can’t have them for something else. If you want a word to refer to a trans woman, make up a new one (e.g., “trans woman”).

      Nobody here (least of all the biologists) is denying anyone’s reality or existence. And we’re not denigrating the humanity or equality of trans people, including the many trans people I know well and care deeply about.

      But we’re (or at least I’m) refusing to negotiate away the broadly accepted meaning of a biological term just because a tiny minority of individuals with AGP or gender dysphoria want it to mean something else. Trans women are humans, with rights, and deserving of equality and respect. But trans women are male.

      1. But somehow “[reserving] male and female for medical or biological contexts…[denies] the lived reality of a large number of people.”

        That is not a fair paraphrase of what Chairephon wrote. Two sentences about different aspects of the subject are cut and pasted – in reverse order – into something new.

        1. Not at all. To show why requires fully quoting. Again I apologize for length and number of comments.

          “Saying that sex is binary because gametes are binary is an ideological statement. At minimum it is buying into the notion that scientists have the authority to define what words mean despite history and common usage. But, generally, the statement is used to deny the identity and even existence of people who don’t fit or don’t feel they fit the traditional categories of male and female.”

          “But I must disagree that making the statement that gamete size determines sex in the context of the complications of defining gender and sexuality in humans is not overlaid with ideology (and it certainly feeds into the ideology of those who would deny the lived reality of a large number of people.) Renaming is not redefining. We can talk about gamete size and its effects on reproductive evolution without using the words male and female. Or we can, as we seem to be doing, reserve male and female for medical or biological contexts and use different words when we are talking about appearance and behaviour. ”

          Both statements refer to the same claim: that the definition of sexes by gamete type is an ideology that harms trans people who don’t fit or feel they fit traditional sex stereotypes. Both aspects of the statement are false, and combining them in either order doesn’t affect their false nature. The scientific definition of sexes is not an ideological claim, and it does not harm trans people.

          1. By omitting the phrase “in the context of the complications of defining gender and sexuality in humans” in your summary, you distorted the meaning of the part before the ellipsis in your reverse-ordered quotation.

    7. At minimum it is buying into the notion that scientists have the authority to define what words mean despite history and common usage.

      Related: this essay by Scott Alexander. Its point being that different categorization schema are useful for different purposes.

  19. Here’s a new article by Colin Wright, in which he demolishes a paper by “a “Multimodal Sex literature survey team” composed of researchers from UC–Berkeley and Loyola University Chicago”, who argue “that sex is best viewed as “a constructed category operating at multiple biological levels” rather than bimodal or binary.”

    “Are There More Than Two Sexes,” by Colin Wright:

    1. [ I like these random “bumps” on comments to jog my thinking ]

      So sex is “a constructed category operating at multiple biological levels”

      I suppose handedness could be argued against this way as well. I’ll try a sort of Devil’s advocate :

      Lots of people use only certain fingers to write – e.g. only a thumb and index finger – so it is wrong to assume they are left or right handed based on that. Because fingers and thumbs individually obey mirror symmetry. The right index finger is, in principle, indistinguishable from the left. We have to use a tool to arbitrarily decide which is left or right.

      So, because some people use only certain fingers and thumbs to write, but not their entire hands, is handedness itself a “spectrum” between left and right?

    2. … yes, I commented before reading. But yes, this is a refreshing piece of writing, appreciate sharing it. A quote :

      “… the quick ascendance of fashionable pseudoscience in academia on the biology of sex is ample reason to worry that this paper will not receive the withering review it deserves.”

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