I already told you I am not continuing this discussion with you. Leave me alone please.

You’re being needlessly antagonistic. Leave me alone please.

This is not in line with current scientific beliefs at all, and most biologists will confirm that with you. Just like most things in biology and life in general, sex exists on a spectrum. We also distinguish between sex and gender. On the biological front alone, one person's sexual phenotype (what they appear to be) is determined by several factors, including but not limited to: how many chromosomes, how many are X or Y for humans (XXY vs XYY), the SRY gene (basically even if you're XY, if you don't have a functional SRY gene on your Y chromosome, you will develop as if you were XX), hormones such as testosterone and estrogen, and hormone receptors. We're not actually clear on what percentage of the population is noticeably intersex, but it's estimated to be on the same order of magnitude as red hair. This is not including trans at all, this is just human biological sex. Social roles are a whole separate, but very important ballgame. It doesn't seem like you're very familiar with current scientific thought on this topic, but if you're ever curious it's really interesting and I hope you investigate more! Fun fact! The Y chromosome is actually disappearing and we're not quite sure what's going to happen when it disappears. Not that it would happen for a very long time, but there's plenty more we don't know.

Let's test this idea and assume for a moment that sex exists on a spectrum.

What specific criteria are you using to place individuals at different points on this spectrum, and how do you calculate if an individual is closer to one end or the other of this spectrum compared to another individual? Which evidence supports these decisions?

Given that most species reproduce sexually, how does this concept work for the vast diversity of non-human species - including ones with a hermaphroditic reproductive strategy?

If a biologist discovers a new sexually reproducing species where the two halves of the reproductive system are embodied separately, how does she work out which are the archetypal females and which are the archetypal males, and how does she determine where she should place any later sampling of the population across the sex spectrum?

I would hope that anyone who confidently proclaims that sex exists on a spectrum will have ready answers for all of these challenges.

Sure! It's pretty trivial. I'm going to assume at least a high-school knowledge of math, since I'm assuming you're unfamiliar with terms like bimodal distribution, categorical data, et cetera. If you're interested in learning more, this kind of thing generally falls under statistics.

So this boils down to the question of essentially "if everything is on a spectrum, how can we categorize it?" and the answer basically boils down to "it's arbitrary." This is essentially called analog-to-discrete conversion. To skip ahead, human sex is on what's called a bimodal distribution. That means there's two big bumps on either end of the spectrum, and very little in the middle, but it's still accepted to be a spectrum. We can just "summarize" it by sorting them into discrete categories. Let's use voltage as an example! Common voltages have 0V for "False" and 1V for "True," right? For discrete signals. But what if the voltage is .3V? If the exact voltage isn't important, we can "summarize" it by setting an arbitrary limit (generally .5V), and then anything below gets summarized to 0V or "False," and anything over or including .5 V gets sorted into 1V or "True," but it's important to note that this has NOTHING to do with the underlying voltage we are measuring. The limit is arbitrary and we're only doing it because the exact measurement in this particular case isn't that important. Science is like this in general: we have the data that we don't understand, and we try to categorize it to make sense of it. But this obviously fundamentally doesn't change whatever we are actually measuring, this is just how we are defining and categorizing that information.

We don't have to imagine other forms of sexually reproducing species; we have many, many, many other examples across life, insects, mammals, bacteria all have different ways of combining genetics and reproducing. Clown fish are pretty much all hermaphrodites and can switch genders under stress, and this isn't that uncommon. There are plenty of examples of intersex individuals who can still reproduce, and plenty who can't for a variety of reasons. Humans are one of the few species that go through menopause, for example. The general idea for this two is talking about general reproductive strategies (for example, XY chromosomes etc etc) is different from talking about an individual, which might be sterile, intersex, whatever. This also is where societal roles come into play et cetera. This is a much larger discussion, though, and it would be difficult for me to summarize here, but I hope I've at least given you some terms so you can understand what's happening. Basically what science does is work from a bottom up approach: we have a lot of data, and we try to understand what is going on by applying labels and seeing if that helps, but these labels and limits are all changing and arbitrary, it doesn't actually affect what we're measuring. We try to use words to describe biology, we can't use words to influence biology, if that makes sense. A statistics class would probably help describe this better.

Edit: So part of the reason why I initially responded was because I was hoping to understand your perspective a little better, since I've heard it before and I find it fairly perplexing. I have a background in biology, science, and engineering in general, and this is just generally how science is done, I haven't said anything particularly controversial here as far as I'm aware. We create models based on what we think is happening, come up with a hypothesis and an intervention and then we experiment on it and try to see how our model compares to what's actually happening. We try to update words to match the data that we see, we don't try to impose words on data, that seems backwards. Are you open to talking a bit more about how you're thinking and reasoning about this?

Just want you to know I appreciate all the hard work you’re putting into trying to educate somebody even if it is likely they will barely register it. I’m sure others like myself found the write up overall interesting and helpful.

Thanks! I find all this super interesting, and I hope other people do too! It's a pretty wild world out there.

Sure! I think I understand what's going on here. I think we're having a few different misunderstandings, let me see if I can describe them.

By "human sex" I'm referring to everything that developmentally contributes to a human sexual genotype or phenotype. Here is a fun textbook example of all the things that go into human sexual development: https://open.lib.umn.edu/evosex/chapter/8-7-variations-in-hu...

From all these variables alone, we know there is some kind of spectrum to human sexual development. When we say something like "binary" that specifically means a discrete data type: true or false (nothing in between). Binary explicitly means there are two options and nothing else (discrete). For example, humans and butterflies, there's zero half-human half-butterfly hybrid. They're discrete. Most things in real life, however, are some form of continuous spectrum, and that's where "spectrum" comes is. We already know based on how many variables go into human sexuality that it's some form of spectrum for an individual, at the very, very least: male, some kind of intersex, or female. It's not binary (two options) for individuals.

(NOTE: also this is just for humans. As I mentioned, "female" and "male" aren't even that useful in a large part of life on Earth. There's a type of sea slug that essentially has penis battles to determine who donates which gamete, essentially, since every individual is capable of both at all times. As I mentioned before, all clownfish are hermaphrodites, they can switch if they need to. Many frogs and lizards can be too. That's why "female" and "male" are such abstract concepts, trying to describe generalized reproduction can be pretty gnarly once you get into any kind of detail, so no wonder the terms are fairly overloaded).

As I mentioned before, some of the factors that go into human sexual development include (1) number of chromosomes, (2) number of X's and Y's, (3) SRY gene on the Y chromosome, if present, (4) human sex hormones including the many forms of estrogen, testosterone, androgens etc, (for this discussion, probably not hormones like FSH, LH etc), (5) the receptors for these hormones. All of these things (and more) go into human sexual development. But you might have already noticed an issue with it: for example, all humans, regardless of sexual phenotype generally have both testosterone and androgens ("male" hormones) and various forms of estrogen ("female" hormones), so how does that work? How can we "measure" "sex"? What even is "sex"?

There's a few different abstractions at play. There's general abstractions like "female" and "male," which have multiple meanings. When we're making big generalizations about reproduction, it's helpful to talk about two general types of roles for mammals. For example, the male and female gametes for mammals are ova and sperm. We can also use it to talk about male and female hormones, estrogen, androgens, progesterone, FSH, LH, testosterone, to name a few. These are useful for talking about general reproductive abstractions, but each individual has aspects from both of these abstractions (estrogen, testosterone, androgens), so it's not a one-to-one mapping. You can't say "oh, human sexuality is determined by chromosomes," because it's not: XXY, XYY, and SRY gene all exist. You can't say "human sexuality is completely based on gametes" because hermaphrodites can have both ova and sperm, so are they male or female? That kind of thing. There's no "one determining" factor for human biological sex. Multiple things go into it, and therefore it's some kind of spectrum based on all the factors that go in.

When we talk about gender this becomes even more readily apparent. There's no "one determining factor" for what makes a woman or a man. It can't be chromosomes, SRY, hormones, gametes, or any one thing alone. We also know that it can't purely be about reproduction: infertile or sterile men and women can still be considered men and women. And this is just English, there are plenty of other languages that have had and have always had more than two main gender roles etc. So what on earth is it? The truth is, it's literally just an arbitrary line in the sand that we're trying to come to some form of consensus on. In general, we've found the most respectful way to do this, is to treat everyone as fully functional humans and have them self-report based on their language, culture, experience et cetera. Language and words are constantly changing and updating with our understanding, so whatever we decide on today, might change in the future too and that doesn't matter either.

Does that help the discussion at all? This is all fairly standard, there are quite a few textbooks on it, including the one I linked if you're interested.

That textbook chapter you linked is quite revealing, thanks. I see that diagram in particular as a good demonstration of how the "sex is a spectrum" concept can't possibly work in practice. The number of arrows criss-crossing back and forth shows how impossible it would be to order disorders of sex development (DSDs) into a spectrum in any logically consistent manner.

More importantly, there's not really any reason to do so, as every one of those DSDs can be explained with the binary sex model and a mechanistic understanding of human sex development. Take 5-alpha reductase deficiency for example, it's caused by mutations in the SRD5A2 gene, which adversely affects conversion of testosterone to dihydrotestosterone, causing internal testes and an underdeveloped penis, but otherwise normal male sex development including testosterone-driven male puberty. It would be pointless to try to place this somewhere on a spectrum, as it offers no additional explanatory power and just obfuscates the detail.

In your spectrum model, you seem to be using the word "sex" to describe some sort of undefined (and apparently undefinable) composite statistical scoring of a set of dissociated sex-linked characteristics, that is focused almost entirely on those present in humans. However, this is not how biologists would typically think of sex. Fundamentally it is about evolutionary questions, like: why does sex exist, why is it a stable reproductive strategy across almost all complex life? And it is about developmental questions: what makes sexed bodies, what are the underlying mechanisms? I don't understand how adopting a "sex is a spectrum" belief would help answer these.

You mention hermaphrodites but again I don't see how the spectrum model does anything but fail here? It offers no useful insights - the binary sex model is perfectly adequate to explain that an individual embodies both female and male halves of the reproductive system.

I hope this helps clarify my points, interested to read your response.

Hi! I'm a little confused what the confusion is. Yes, talking about binary terms and using them as an abstraction and a summary is perfectly convenient, and can be useful, but that doesn't change the data. It's just a summary of a very complex system. The terms "female" and "male" have multiple definitions because of that. Here's an example from the dictionary:

Female: (1) Of or denoting the sex that produces ova or bears young. (2) Characteristic of or appropriate to this sex in humans and other animals. (3) Of or denoting the gamete that is larger and less motile than the other corresponding gamete. Used of anisogamous organisms. (4) Designating an organ, such as a pistil or ovary, that functions in producing seeds after fertilization. (5) Bearing pistils but not stamens; pistillate.

There's a few others, but that's why both males and females have both "male" and "female" sex hormones. They're different levels of abstraction. Yes, talking about these abstractions is very convenient for reproduction, that's why we created them, but they're inherently abstract. Just like talking about a voltage as 0V or "OFF" or "FALSE" when it's actually 0.12323V is perfectly convenient and useful.

I actually talk to several biologists on a regular basis, and this is all pretty standard, because mostly what we're doing is just talking about how science works and data.

Being dependent on multiple variables, having that many possible dimensions, makes the data a spectrum. We can summarize that data in arbitrary ways, including drawing an arbitrary line and sorting them into categories, but that doesn't fundamentally change the data. No one is confused when we talk about male and female hormones within an individual. If a person who presents as phenotypically female and considers herself a woman comes into a doctor's office and it's discovered she has XY chromosomes, no one is that surprised: we know about the SRY gene, we know about lack of testosterone receptors etc etc, we understand this is normal. Or if someone presenting as a woman comes in with a beard, no one is surprised. Hirsutism in PCOS is fairly common. We know men and women have both male and female hormones. Again, we know how all of this works, so no one is surprised. Talking about abstract concepts for reproduction is a useful model, but it is just a summary and an abstraction, and it does not change the diversity of human sexual development. Words and abstractions do not change actual biology. We change words and abstractions based on increased knowledge of biology. We can talk about abstractions until we're blue in the face, but ultimately it's only a useful way of trying to describe the actual data. Does that make sense?

It makes sense but it is a false framing. The whole point of female and male is to distinguish the two reproductive roles in sexually reproducing species, whether those are hermaphroditic or gonochoric. The sex binary is based on anisogamy, that is, two classes of gamete being of unequal size.

All the "dimensions" you mention - hormones, chromosomes, etc. - are downstream of this, and they vary across species (e.g. some don't use hormonal signalling for reproduction, but neuropeptides). While there are variations, including those in sex development that may lead to a disordered system, it doesn't logically follow that sex itself is a spectrum.

To take one of your examples: a hirsute woman with elevated testosterone due to PCOS is female, and having this condition doesn't make her less so. Indeed, this is a condition that only affects people who are female, tied to ovarian function. Her condition can be described perfectly well without pretending that her sex lies on some sort of ill-defined spectrum.

Your comment about "drawing an arbitrary line" doesn't really fit with how biologists see this either, as it's not arbitrary at all but is based on understanding the mechanisms of reproductive function and development. And not based on gathering and arbitrarily categorising data without reference to the underlying system. The mechanistic insight is important.

Going way back upthread, this was originally about fairness in sport, male physiological advantage, and the other commenter getting surprisingly cross at me describing males as male, as he seemed to think there are medical interventions that can be performed on humans that convert males to female, which is not the case. Then you commented stating that sex is a spectrum. This is typically introduced into an argument to try to bolster the claim that it is possible for humans to change sex, the idea being to redefine sex as a cluster of characteristics to be considered separately to reproductive function, and then argue that because things like breast size (through a male taking exogenous oestrogen) and genital morphology (such as surgically inverting a penis to make a hole, and lining the entry point with scrotal tissue) can be changed, this constitutes a change in sex (e.g. a male, by this redefinition, supposedly becoming more female).

So that leads into another issue of why this "sex is a spectrum" idea has been introduced to the world at large. It is not to gain greater understanding of reproductive system, sex development and evolutionary questions regarding sexual reproduction. We can see even from this back and forth between the two of us how it only has rhetorical use, with my requests for precise detail on how this model might work in practice remaining unanswered.

Thanks for the discussion, interested to hear your thoughts on this.

Also one more thing of note before you go into "but intersex is just error":

"Errors" are important in models. Look up Type 1 and Type 2 errors. If I had a model for hair color, and it couldn't explain red hair, it would be a pretty terrible model. As I mentioned earlier, red hair and obviously, visibly intersex are about on the same order of magnitude.

To further illustrate this concept, consider humans and horses. You'll notice there aren't human-horse hybrids. We can come up with a criteria or a model to separate humans and horses with 1's and 0's and there's nothing in the middle. That's an example of a binary system. We could come up with a bunch of terrible models too that can't differentiate between the two ("mammals"). But ultimately, I could disprove your argument about transgender in sports even ASSUMING a binary model in sex because it's pretty fundamentally irrelevant. If we can't measure the difference between two things (sports performance between ciswomen and transwomen after 2 years of hormonal therapy), then the difference doesn't really matter. The fact that there's transMEN regularly playing in the Olympics is also fairly revealing.

I think you've missed my key point which is that sex is fundamentally defined by gamete type, and is not a post-hoc clustering of traits. The underlying biological concept is reproduction via anisogamy, which is robust across a multitude of species, humans included. Anisogamy, which you should know as you studied biology, is a reproductive strategy involving the fusion of a small gamete with a large gamete, producing a new individual.

In hermaphroditic species, the two halves of this reproductive system are both embodied in each individual, and are active either consecutively (as with sequential hermaphrodism) or concurrently (as with simultaneous hermaphrodism). In gonochoric species, these are embodied in two distinct classes of individual, via two distinct developmental pathways. Humans are a gonochoric species.

When you claim "sex is a spectrum" or "sex is bimodal", you are confusing sex characteristics with sex. These characteristics are species-specific, whereas sex itself is a cross-species categorization in which sex determination, sexual development, and sex characteristics will vary.

You comment "let's hypothesize that human sex is [always] determined by [XX or XY] chromosomes" and make the argument from this that conditions like Klinefelter syndrome and SRY-negative XY chromosomes disprove that hypothesis. Yes it does, but the hypothesis was flawed in the first place. There is no "human sex" that is different to "sex". More precisely, what you are actually talking about here are the mechanisms of sex determination and sex differentiation in humans. Analyses of DSDs have been very useful in gaining a deeper understanding of these, just as analyses of rare pathologies in other systems do.

Claiming "sex is a spectrum" adds no utility here. It conflates development with definition, and is used for rhetorical ends rather than advancing scientific knowledge. As our conversation has shown, there's not even any consistent understanding of what this spectrum might look like or where individuals should be placed on such a spectrum.

You mention sterility, but this doesn't change someone's sex. The elderly and infertile retain their sex because it's developmental, not performative. This is also why, for example, we can recognize worker bees as female despite them being infertile.

Going back to sports, the available evidence does not show that male athletes weakened through testosterone suppression are equivalent to female athletes. It is not possible to unbuild the body of a human male and rebuild it as female. Your claim that "scientists have already looked into this, and they determined that after two years of hormone therapy transwomen are fairly hard to distinguish from the natural variation in ciswomen for all their metric" misrepresents the research and doesn't take into account what we see performance-wise when these males are allowed to compete in women's sport. Note that while we observe "transwomen" dominating women's competitions, we don't see the same for "transmen" in men's categories, even when they've been on testosterone for many years. This in itself highlights the impact of sex differences in athletic performance.

Let me see if I understand your argument. I'm not sure about several aspects, and it sounds like you have multiple arguments.

[1] Sex is purely defined by gamete size. (Already incorrect, but if that makes the argument easier we can play pretend.) [2] Humans are a gonochoric species. (true) [3] In gonochoric species, unlike simultaneous or sequentially hermaphroditic species, gamete-size generally remains constant throughout the lifetime of the species (also true). [4] Therefore, humans generally maintain the same gamete size throughout an individual’s life (sure, not many people are switching their gamete size throughout their life).

We’re in agreement humans aren’t generally switching gamete sizes through an individual’s lifetime. That would honestly be ridiculous and no one is arguing this. However, while some of these ideas are true and are convenient for talking about various species, it’s not always correct when talking about individuals.

An example of this is using generalized words or labels on anything or anyone. “English-speaking” could mean someone who speaks only English, someone who speaks only a little English. What matters is context and relevance.

Human sexual phenotype can be described by three discrete categories if you want: male, female, intersex. This is what I mean by “spectrum,” I’m literally just mentioning it doesn’t fit the definition of binary (being able to be completely described with 0 or 1 without loss of data). Please see my previous explanation for further details on this. I literally did a proof-by-contradiction.

In individual humans, our genotypes do not always match our phenotypes. For example, XY + No SRY would be functionally identical to XX. XXY and XYY are both viable and happen, and a lot of people might not even realize they don’t have the chromosomes they think they do.

Obviously intersex is about the same proportion of the population as red heads, for context.

So intersex is a perfectly normal and natural human sex phenotype. There are literally human beings living with both gamete sizes for their entire lives, living hopefully happy, healthy lives. This has nothing to do with gonochoric or hermaphroditic species. We’re still a gonochoric species, even if intersex humans exist. Humans aren’t spontaneously changing gamete sizes throughout their lives, but some people literally just have both and have had both since birth. That’s just how it is.

So human sexual phenotypes don’t always match genotypes. They mostly do, probably over 80%, but we’re not honestly sure about the true rate of intersex mostly because it matters so little. As you saw in the textbook chapter I referenced, human sexual phenotype has many factors, but yeah, we can summarize it with three discrete categories: male, female, intersex. That’s again, just how it is. We can debate what to do with intersex, sure, but it honestly doesn’t matter very much.

Your sports argument seems a little strange, I’m honestly not sure I fully understand it:

[1] Gamete size is the only determining factor in human sexual phenotype [obviously incorrect, please see that book chapter] [2] As a society, we divide up sports by sex or gender [yeah, sure, we sometimes do that] [3] Gamete size is relevant in sports [very obviously incorrect, but what you probably mean is that gametes CORRELATE with testosterone, muscle mass differences etc, which is true, and we can measure those correlations] [4] People can’t change their gametes [no one is talking about this, ridiculously irrelevant] [5] Therefore people can’t change their sex?

Trans people exist. We have accepted that there is both biological sex and gender (social construct). Just like genotype and phenotype, they normally match, but sometimes they don’t. I honestly don’t understand why there’s any upset about this, there’s been evidence of this going back pretty far throughout history. We literally get the word hermaphrodite from the ancient Greeks.

So do you only care about transpeople because of sports? There are transmen in the Olympics, so I think they’re doing fine, and I literally linked several papers on transwomen in the Olympics, but I can link them again.

We’ve measured it. This is what science does.

More links: Sex differences and athletic performance. Where do trans individuals fit into sports and athletics based on current research? https://www.frontiersin.org/journals/sports-and-active-livin...

SPORTS AND PERFORMANCE IN THE TRANSGENDER POPULATION: A SYSTEMATIC REVIEW AND META-ANALYSIS

https://www.scielo.br/j/rbme/a/CDkTksYcMPcKYTHGfcJLX4K/?lang...

Transgender Women in the Female Category of Sport: Perspectives on Testosterone Suppression and Performance Advantage

https://link.springer.com/article/10.1007/s40279-020-01389-3

Honestly, if there is some advantage, they’ll measure it, try to understand it, and then change the rules. I’m sure it’s an ongoing discussion. I’m not sure I see your point with all this.

> We have accepted that there is both biological sex and gender

This is close to the real point of dispute, on which there are approximately three main positions, which amount to two political camps because the last two positions drive the same political conclusion (and can be hard to distinguish):

(1) Sex, socially-ascribed gender, and gender identity are real and distinct things, all of which are (or in the case of active gender should be) multidimensional spectra though they may have something like a bimodal distribution which can naively look binary, and normatively ascribed gender should be aligned to gender identity;

(2) Sex and ascribed gender and gender identity are real and distinct things, the former is a crisp binary defined by particular physical traits (which traits varies among holders of the belief and over time; gross anatomy was popular, combination of X & Y chromosomes was popular, gamete size is currently the most popular), and normatively both ascribed gender and gender identity should conform to sex; when gender identity specifically does not it is a kind of mental illness, that should be treated and corrected, not accommodated and validated;

(3) Sex and ascribed gender are real and distinct things with the nature and relationship described in #2, but gender identity does not exist and is a myth invoked to excuse personal moral deviance and/or sexual perversion.

Thanks! I'm on the biology side of things, so I tend to avoid going into gender because I don't understand it as well, but the biology seems clear enough. The gender side also makes sense to me broadly, since we have complex and varied cultures, and having a term to talk about different societies also seems helpful. There are multiple languages and cultures with explicit terms for intersex, for example.

I'm not super clear on why gamete size has become a popular argument for a so-called binary model, since intersex still exists and there are individuals with both gametes. Not to mention, for sports, gamete size seems much less relevant than hormones and natural variation within each sex/gender, and that seems to be the favorite example. Do you have any insights as to why gametes have become a popular argument?

I think you're still missing several key points. Biological sex is more than just gametes. This isn't some weird, niche theory, this is just basic biology. Even if it were just gametes, there are still several intersex conditions. The data is not inherently binary, we measure models by their outputs. This is a common misunderstanding from those not very familiar with how models are used in science and math.

> You comment "let's hypothesize that human sex is [always] determined by [XX or XY] chromosomes" and make the argument from this that conditions like Klinefelter syndrome and SRY-negative XY chromosomes disprove that hypothesis. Yes it does, but the hypothesis was flawed in the first place. There is no "human sex" that is different to "sex". More precisely, what you are actually talking about here are the mechanisms of sex determination and sex differentiation in humans. Analyses of DSDs have been very useful in gaining a deeper understanding of these, just as analyses of rare pathologies in other systems do.

I'm literally talking about human sexual phenotype. That's it. Phenotype does not always match genotype, that's the whole point. Do you understand the difference between genotype and phenotype, because that's half the point of what I've been discussing. You've also missed my entire point about how we measure models in science and what a model is. That whole demonstration was to show you how we actually test models in science.

> Claiming "sex is a spectrum" adds no utility here. It conflates development with definition, and is used for rhetorical ends rather than advancing scientific knowledge. As our conversation has shown, there's not even any consistent understanding of what this spectrum might look like or where individuals should be placed on such a spectrum

I'm not claiming anything. Human sexual phenotype is not binary, as demonstrated through a binary model with proof by contradiction. This is how we evaluate models. Even if we assume a binary model, as I've mentioned, it doesn't actually matter much since there isn't a huge difference between the two genders for most sports. There are measurable differences for others, but that has nothing to do with gamete size and everything to do with different levels of hormones like testosterone, estrogen et cetera, not gametes. Once again, there is significant overlap between the two sexes to start with.

> Going back to sports, the available evidence does not show that male athletes weakened through testosterone suppression are equivalent to female athletes. It is not possible to unbuild the body of a human male and rebuild it as female.

I'm honestly baffled by this statement. No one is "rebuilding" anyone or anything. I'm not actually sure what you mean by this, but this just further demonstrates that we've moved very far away from anything like science. This just sounds like a strange straw man. If you can't even acknowledge that genotype can be different from phenotype, then there's no point in further discussion, this just seems silly.

> Going back to sports...

Men and women have a lot more overlaps than differences. This has been demonstrated. It was actually surprising to me when I first learned about it. We literally do see plenty of transmen in the Olympics, so I'm not quite sure where you're getting this from. Yes, there are differences too, but again, it has nothing to do with actual gametes and mostly it has to do with testosterone and possibly different forms of estrogen etc. What you're calling "sex characteristics."

Here are a few papers: Sex differences and athletic performance. Where do trans individuals fit into sports and athletics based on current research? https://pmc.ncbi.nlm.nih.gov/articles/PMC10641525/

Effect of gender affirming hormones on athletic performance in transwomen and transmen: implications for sporting organisations and legislators https://bjsm.bmj.com/content/55/11/577?ref=goodoil.news

Transwomen might still be a little faster than ciswomen at least a year after hormone therapy, but most of the other metrics were within normal variation after 1-2 years hormone therapy.

Sexual reproduction certainly does involve more than just the gametes themselves, but the definition of sex is based on gametes - and that they comprise two distinct classes of cell, in size and form. Otherwise, in gonochoric species, how would anyone know which sex characteristics are female and which are male, and how the female and male sex development pathways differ? And in hermaphroditic species, which anatomical and cellular structures correspond to the female and male halves of the reproductive system. It all comes back to anisogamy. This is the fundamental definition of sex.

Regarding your second point: that there are variations in phenotype, some of them disordered, doesn't mean that "sex is a spectrum". For DSDs, we can describe them in terms of specific developmental differences compared to normal sex development. These are a set of discrete conditions that can be understood without conjuring up ill-defined spectrums. In fact, DSDs in humans have given those who study developmental biology considerable insight into the mechanisms of human sex development more generally.

I see after reading those papers you linked that they further illustrate the point I made earlier: that suppression of testosterone weakens males in some ways, but they still retain physiological advantage from testosterone-driven development earlier in their lives. To advocate for the inclusion of such males in female competitions is to advocate for female athletes to compete at a disadvantage.

If you look at the world records for pretty much every sport, the difference between female and male athletes is very clear. That there exists some overlap between weaker-performing male athletes and higher-performing female athletes doesn't mean that male advantage is significant in almost all sports, especially in ones more reliant on raw strength, such as weightlifting.

You mention the transmen who compete in the Olympics. This is true but they are competing against other female athletes, e.g. Hergie Bacyadan in the most recent Olympics, competing in women's boxing (and in that same Olympics, two males - controversially - won gold, in two other women's boxing divisions). None of them would even come close to qualifying against elite male athletes.

Here is the definition of sex from the Merriam-Webster dictionary:

1a: either of the two major forms of individuals that occur in many species and that are distinguished respectively as female or male especially on the basis of their reproductive organs and structures 1b: the sum of the structural, functional, and sometimes behavioral characteristics of organisms that distinguish males and females 1c: the state of being male or female 3: genitalia

Among those who study gender and sexuality, a clear delineation between sex and gender is typically prescribed, with sex as the preferred term for biological forms, and gender limited to its meanings involving behavioral, cultural, and psychological traits. In this dichotomy, the terms male and female relate only to biological forms (sex), while the terms masculine/masculinity, feminine/femininity, woman/girl, and man/boy relate only to psychological and sociocultural traits (gender). This delineation also tends to be observed in technical and medical contexts, with the term sex referring to biological forms in such phrases as sex hormones, sex organs, and biological sex.

https://www.merriam-webster.com/dictionary/sex

So what dictionary are you using where "sex" is purely defined by gametes? Please use references and support. I have literally provided studies, textbook chapters, and dictionary entries. You're not actually arguing anything, or if you think you are, you're begging the question. Sex is based on more than gametes and we've known that for decades.

> I see after reading those papers you linked that they further illustrate the point I made earlier: that suppression of testosterone weakens males in some ways, but they still retain physiological advantage from testosterone-driven development earlier in their lives. To advocate for the inclusion of such males in female competitions is to advocate for female athletes to compete at a disadvantage.

They literally concluded there wasn't a measurable difference in most of the aspects that they're considering after two years (though there was still an advantage in running after 1 year), so that's a very creative interpretation. There are more studies too, but I can see there's limited point in listing them, since you're reading with your own bias.

Also, keep in mind with the papers that I provided, the authors of these papers are PhDs in this specialty studying trans individuals. Meaning that people who are way more knowledgeable about all this view trans individuals as exiting, since before you seemed to be denying that. Also please notice, that they aren't measuring gametes, they're measuring the effects of hormone therapy specifically and how that might apply to sports. Rules etc in sports, sure, we can measure and change them, but there are plenty of phds out there studying both gender and sex. If you're trying to argue that nuances in the Olympics and college-level sports means trans can't exist, that seems like very faulty logic.

> If you look at the world records for pretty much every sport, the difference between female and male athletes is very clear. That there exists some overlap between weaker-performing male athletes and higher-performing female athletes doesn't mean that male advantage is significant in almost all sports, especially in ones more reliant on raw strength, such as weightlifting.

There are many, many sports where this is not the case and separating between men and women happened late, if at all. Sharp shooting et cetera. There are other sports where yes, there are measurable differences. Testosterone can help in certain sports, that's certainly true, but though that CORRELATES with gametes, it's not absolute, once again demonstrating that what we're actually interested in in sports is testosterone etc, not actual gametes.

> You mention the transmen who compete in the Olympics. This is true but they are competing against other female athletes, e.g. Hergie Bacyadan in the most recent Olympics, competing in women's boxing (and in that same Olympics, two males - controversially - won gold, in two other women's boxing divisions). None of them would even come close to qualifying against elite male athletes.

Incorrect. The transmen are competing against other men. Chris Mosier had an injury at the Olympics, which is unfortunate, but he qualified. In 2015 Schuyler Bailar competed in NCAA Div 1 men's team and did pretty well, top 15%. 2018 Patricio Manuel boxed professionally and won. Transathletes are a small percentage of the population and haven't been allowed at the Olympics for very long, so we'll see what happens there.

Overall, I'm not sure what elite sports has to do with the existence of trans people or human sexual development phenotype or how sex is "only gametes" (or chromosomes, you seem to go between both). The rules in elite sports are always changing, and I'm sure they'll change more. You've essentially assumed your gamete argument is true, despite going against the dictionary, the book chapter I listed, and the studies that I provided, all of which acknowledge trans individuals. This is called "begging the question." If we're going into rhetoric, this is sounding very motte-and-bailey fallacy.

One thing I will say, is that fundamentally science is about asking questions and measuring phenomena, generally using models etc to try to discern causality (probability and statistics). Science is NOT about telling people who or how to be or denying people's experience. Science can tell us what will happen when we take a drug, not if we "should or shouldn't" take the drug (that's for us to decide). In studying other cultures or experiences, science isn't about labeling "good" or "bad," or erasing experiences we don't understand. For example, we know from studying many other cultures and languages that there are multiple understandings of "sex" across cultures, especially where there are explicit terms for intersex et, which is why terms like "gender" can be useful.

I'm not sure why you have such a strong reaction to "trans people exist" or why you're trying to act like your views on it are "scientific," when I have provided (1) textbook, (2) dictionary, (3) studies showing that your views that (A) trans people do not exist and (B) sex and sexual phenotype are only determined by gametes are not supported by science and you have fundamentally misunderstood several key aspects of biology and math (binary vs bimodal). I've provided explanations for how we use models in science and how we talk about data. If you're actually interested in learning about this stuff, I hope some of the resources I have listed are helpful. Otherwise, I'm going to assume that this is not a productive discussion of two people trying to understand the world better. I'm sad this is your view of what science is, and if you're ever actually curious about this kind of thing, I hope you find it interesting.

It is very straightforward to show that sex is defined by gametes.

Imagine a biologist discovers a new sexually reproducing species. She does not yet know whether it is hermaphroditic or gonochoric, nor, if gonochoric, which individuals are female and which are male.

What does she investigate to find out?

She examines gamete production: which gonads produce small, motile gametes and which produce large, nutritive ones. That is the criterion that has defined "female" and "male" across all sexually reproducing organisms for well over a century of modern biology.

Everything else - chromosomes, hormones, genitalia, secondary characteristics - are species-specific downstream mechanisms that evolved to achieve that single binary outcome. They are not the definition itself.

I did ask a version of this earlier in my first reply to you, but I think its significance may have been missed. Anyone with a solid grounding in biology should recognise immediately that gametes are the root criterion. No other answer makes sense.

> It is very straightforward to show that sex is defined by gametes.

I read and corrected your previous comments then, and I will correct them again now. I know this is more or less what they teach in middle and high school biology, just like you might have learned "electrical current is like water flowing between between two voltages" (not a good metaphor, but one that is often taught) and "evolution is the survival of the fittest" (incorrect, but still sometimes taught). What you learn in college is that a lot of the metaphors that were helpful at the beginning can actually make it harder to learn a more nuanced view that's closer to reality. But there's a reason the dictionary definition is different and not just based on gametes. You're confusing applying abstract concepts to individuals.

>She examines gamete production: which gonads produce small, motile gametes and which produce large, nutritive ones. That is the criterion that has defined "female" and "male" across all sexually reproducing organisms for well over a century of modern biology.

Correct, when talking about species as a whole, this is quite useful. "Female" and "Male" can refer to many different types of species. We even refer to asexually reproducing species as "females" by default. Just like "English-speaking" can be a useful general label in numerous contexts. It's great being able to talk about "English-speaking people" as a generalization, but that label doesn't differentiate between someone who speaks at a first-grade level and a college-level. When we're talking about an individual person, we normally take a more nuanced view, as is reflected in the data.

Please see my previous comments on models, binary, etc. Being able to apply a label to something does not necessarily make it true, but we're back at the beginning and I see no point in going over my points again. You're also essentially confusing genotype and phenotype. There's a reason biologists differentiate between that. But again, I've gone over all this already. As someone with a solid background in biology, yes, gametes are important and are great abstractions for talking about specific things, but more than just gametes go into human sexual phenotype and we've known that for decades.

Anyone who has any kind of background in science or engineering at a college level should be able to understand models and data terms, like binary, type 1 and type 2, error, and abstraction. This is fundamental. If you're actually interested in learning more, please reread my previous comments.

* Edit: I missed one of your points.

> Regarding your second point: that there are variations in phenotype, some of them disordered, doesn't mean that "sex is a spectrum". For DSDs, we can describe them in terms of specific developmental differences compared to normal sex development. These are a set of discrete conditions that can be understood without conjuring up ill-defined spectrums. In fact, DSDs in humans have given those who study developmental biology considerable insight into the mechanisms of human sex development more generally.

I already addressed this in a previous comment, but please see Type 1 and Type 2 errors in models. I think the example I used in it was there are no horse-human hybrids (outside of fiction) because we can create a true binary model with horses and humans. That is NOT the case for male and female phenotypes in humans. There are individual humans with both organs, different gametes, different chromosomes, both characteristics etc etc. Obviously-intersex are on the order of red hair in humans, so "it's uncommon" isn't a good counterargument. Again: type 1 and type 2 errors in models.

For your other points about disorders, let's use red hair again. Red hair isn't "a disorder," even though technically it's a result of a type of melanin dysfunction: "Red hair occurs due to a genetic mutation in the MC1R gene, which affects the production of melanin pigments in hair. This mutation leads to higher levels of pheomelanin, resulting in the characteristic red or ginger hair color." It's a normal, but uncommon phenotype. We understand why it happens and how it occurs, similar to intersex. We don't actually know all the types of intersex or how they interplay with each other, but either way, it doesn't honestly matter. If someone appeared with genuine blue-pigment hair, that would break our model. Red hair is just another phenotype in the spectrum of hair colors. Same with grey hair. Same with intersex.

We can list all sorts of things as "disorders" or whatever, which is why we use models to discuss data in science, it's a more structured way of evaluating the world. Types of errors are important in evaluating models. There is as-of-yet no binary model for human sexual phenotype. We still generally sort everyone into two discrete categories, but that's what we choose to do as a society, the data itself is not binary. Just to emphasize this once again: models and data how we evaluate and categorize the world using science. Everyone can apply whatever label they want to something. That isn't science. We make progress in science by evaluating models.

Sex is still very bimodal, no one is arguing that, but fundamentally it's a spectrum. It is not just gametes. We have some of types of intersex listed, sure, but it's also just a normal, uncommon human phenotype.

Intersex has provided insights and is interesting to study. We're in agreement there.

For sports, we're not talking chromosomes or gametes at all. They're irrelevant. What they're actually measuring and evaluating is testosterone, muscle mass, etc, which does CORRELATE with gametes, yes. If we're actually concerned about sports, we'll measure and see what happens. But once again, I can assure you that it has nothing to do with gametes or chromosomes or whatever, and a lot more to do with hormones, muscle mass etc. The studies I listed seemed promising, but I'm sure we'll learn more over time.

I think we're in agreement that ultimately, we want athletes to be able to participate in a way that seems fair, by whatever measure that may be. I'm sure they'll collect more data and we'll decide what we want to do as a society. I am certainly not an expert. The studies I mentioned and several others seem promising. There have been some transmen in the Olympics against other men, though not many. There have also been women who have won gold against men in other sports (skeet I think?) before they were separated. There are obviously several sports where men have measurable advantages to women. For trans-athletes, I suppose we'll see what happens and what the data says.

Absolutely none of this justifies statements such as "transwomen are men." They are not. Sex and gender are both real, useful terms, and they have their own applications. Also, much like genotype and phenotype, they do not always match. Sexual phenotype does not always match genotype (chromosomes), organs etc.

We can see and measure the two groups. We can talk about fairness in sports. It is perfectly fine to talk about measuring differences between transwomen and ciswomen. It's perfectly fine to talk about measuring differences between transwomen and (cis or trans) men. It's even perfectly fine to talk about concern for fairness in sports with the inclusion of transwomen and transmen. All of that is fine.

It is not okay (disrespectful) and incorrect to (1) say that they don't exist (2) say that they're something other than what they identify as. None of that is supported by science. Sex and gender as useful, distinct terms are supported by science. We use those terms to study multiple species, cultures, in whatever forms. Intersex is an uncommon, but well supported phenotype that we literally have records of since ancient times and has been fairly common across many cultures. And across many species. It's honestly so broad it is difficult to define. Literally we have entire hermaphroditic species AND hermaphroditic individuals in non-hermaphroditic species. Similar to homosexuality, it's just a natural phenomenon that happens. You can view trans as part of intersex, or as more of a sociological construct, like gender identity. The data is there.

If you're actually just concerned for fairness in sports, then you could have talked about the athletes in a respectful way ("I'm concerned about the fairness of transwomen in sports with ciswomen"). You chose not to. In general, your way of thinking sounds more like religion than science, and I've heard it all before already.

Science isn't a rhetorical weapon. It's a way of studying, evaluating, and communicating about the world, not imposing judgement on it. There is plenty of data supporting trans, gender, intersex, whatever. There are also plenty of respectful ways to discuss this topic, as previously mentioned.

Why go out of your way to talk about it in a disrespectful way? Why hide behind trying to sound scientific, when it's clear you don't have a background in it? Why the focus on sports?

I think it's time we stop dancing around the topic and get to the meat of this discussion.

I do not consider it disrespectful to state someone's sex, particularly when it's relevant to the topic.

Consider my original comment on this thread:

"Most of the actual work to stop males from competing in women's sports, through evidence-guided changes in policy, has been driven by female athletes who are directly affected by this, feminists and feminist allies, scientists that study sex differences, and experts in the philosophy of sport.

That it's become such a well-known topic of contention is because sports are a spectator event and there have been some very high-profile instances of this unfairness towards female athletes."

Followed by this reply to a user who had a different view:

"They are male, and retain male physiological advantage even if they undergo interventions like testosterone suppression. It's not the only route by which a male athlete with such advantage might compete in women's sport, nor is it an issue limited to the USA. This is a broader issue affecting the fairness of women's sport in competitions across the world.

For instance, all three medallists in the women's 800m at the 2016 Rio Olympics were male. They had been issued with female birth certificates by their home countries due to having underdeveloped external male genitalia - and therefore according to the rules at the time could enter as female - but they still benefited from testosterone-driven development."

There is no disrespect in these comments.

As to why our conversation has focused on sports and sex differences, it is because it was the original topic before you joined the discussion.

As a side note, it's pretty widely accepted that referring to humans as "male" or "female" instead of "men" and "women" in general is dehumanizing. Using it as an adjective "male athletes" isn't considered disrespectful. Your personal opinion that it is NOT disrespectful isn't super relevant, since there are obviously more respectful and relevant terms (transman, transwoman, cis, pre- and post-transition). You weren't actually referring to all "males" in general in the previous discussion, you were specifically talking about transwomen athletes post-transition competing against ciswomen. If this wasn't intentional, then that was part of the confusion.

Some of your comments seemed to be removed, but for clarification, transwomen are women and transmen are men. Why not just use those terms in general? Why say "males," when you are actually talking about transwomen, which is a more accurate and relevant description? Then talk about pre and post transition, since that is the whole point of the discussion surrounding sports (criteria and debates around transition).

My comment is too long, so I'm going to try to separate it into 2.

> Your comment about "drawing an arbitrary line" doesn't really fit with how biologists see this either, as it's not arbitrary at all but is based on understanding the mechanisms of reproductive function and development…

I talk to biologists all the time for work. I studied biology in college and I work in science and engineering. This is how we talk about data and models in science. What I'm seeing in your response is a fairly deep misunderstanding in how science works, and that's why it might appear to you like I'm not actually answering your question. I am not "proposing a new model" about sex being a spectrum.

Let's take a step back and look at how science works and hopefully we can address this misunderstanding. I'll start with the fundamentals.

We use words to communicate about the world, but they're an imperfect medium. As a quick example, I can call an ant hill a "mountain." What information I might be trying to convey depends on: (1) definition, maybe my definition of mountain is .5 cm, (2) context, maybe I'm speaking metaphorically, (3) relevance, maybe I'm speaking from the perspective of an ant. So key things in communication are (1) definitions, (2) context, (3) relevance. Whatever word I call the object doesn't change the object in any way. This is because all words are representations (or models) of the world, and all models are, by nature, false. They cannot possibly describe every aspect of reality. Words are only as useful as the information they convey. So how can we evaluate the information in words or models?

We evaluate models by treating them as black-box functions and comparing their output to reality. We’re trying to measure how useful or predictive the model is.

How do we do this in practice? We (1) propose a hypothesis, (2) decide which variables are relevant (3) decide on necessary and sufficient conditions or some kind of function. Then we run that function and compare the output of our model to what we measure in reality.

Let’s look at a binary model for human sex. Our hypothesis is that we can define a set of criteria or definitions such that the output is either 1 “female” or 0 “male”. The definition of binary means that it can be fully and completely described by 1 or 0, nothing in the middle. For example, TRUE or FALSE is binary.

Let’s hypothesize that human sex is determined by chromosomes, so therefore XX is female (1) and XY is male (0).

XXY exists (Klinefelter Syndrome). That breaks our model. We can update our criteria. [XX is female] (1) and [XY and XXY are male] (0).

XY + no SRY exists. That also breaks our model. We can update our criteria. [XX and XY + no SRY is female](1) [XY + SRY and XXY is male (0)].

Lots of intersex conditions exist. What does that mean for our model?

To skip forward, we still do not have a defined set of necessary and sufficient criteria where we can describe all outputs of human sexual development with 1 or 0. This means the assumption that the output is binary for our model is broken. Can we still sort everything into binary categories? Sure. Nothing is stopping you from labelling something, but we understand that we’re giving up information while we’re doing this. When we talk about binary models, what we’re referring to is an output of a function or model, not just applying the labels. We do this because we can obviously just apply whatever labels to anything, there’s nothing “scientific” about it. So what’s actually important in evaluating that model is the necessary and sufficient criteria we come up with: the actual function, model etc. This is what I mean by “binary system.” You can still obviously sort the data into binary categories, but the underlying data is fundamentally a spectrum.

This is essentially called a “proof by contradiction.” We had a set of necessary and sufficient conditions, a set of defined definitions (like binary), and we found counterexamples for each one.

Another perspective could be: if I see an individual, what are the chances I could correctly guess characteristics about them (chromosomes etc) based on their phenotype? For male and female, you might be able to fairly accurately guess certain characteristics about them, probably somewhere around 80%. Does that mean that it's impossible for us to sort every individual into two categories? No. But being CAPABLE of sorting or labeling them into two categories does NOT make something binary.

To be honest, the existence of intersex alone should be sufficient to tell you that male and female are not completely “binary” concepts. So we’re dealing with some kind of discrete or continuous “spectrum.” For convenience and simplicity, let’s say it’s male, intersex, female, so discrete but not binary.

Second part:

Now let’s start to address some of your points.

> "The whole point of female and male is to distinguish the two reproductive roles in sexually reproducing species, whether those are hermaphroditic or gonochoric. The sex binary is based on anisogamy, that is, two classes of gamete being of unequal size."

Yes, that's why "female" and "male" are useful abstract concepts specifically to help talk about reproduction in several species. Using these two terms, we can talk about a diverse spectrum of reproductive strategies, including hermaphroditic and gonochoric.

I think your argument breaks down to:

[1] The terms male and female are strictly to distinguish between gamete size in gonochoric species. [Already incorrect, but sure, that’s one possible definition we can use] [2] Humans are a gonochoric species [yes] [3] Therefore ALL humans are either male XOR female

Is this your argument? Because it can pretty quickly be disproven with one contradictory example: intersex humans exist. Deductively arguing from abstracts also means its application is quite limited. For example, it inherently assumes humans are reduced to their reproductive function, which is obviously false. If we’re purely arguing from the perspective of ability to reproduce, then do you have a larger category in mind for “sterile” humans, including infants, the elderly etc? Obviously not all humans are capable of reproduction, which is why it’s useful as an abstract, but that quickly falls apart once you look at concrete examples like individuals. Again, just because you CAN label everything in a binary way, it doesn’t actually mean that the underlying data is binary.

> To take one of your examples: a hirsute woman…

From your response, I don't think I was very clear with these examples. Let me see if I can make my points more clearly.

Every human has male and female aspects. If you look at one individual, how accurately could you predict certain characteristics about them?

If I say "this person has a beard," could you immediately say with 100% confidence that it was a "male"? No. You could probably guess with fairly high accuracy, about 90%, but you could not be 100% confident.

What I was hinting at with these examples is that there is no "necessary and sufficient" definitions of "male" and "female" for individuals where you can predict with 100% accuracy. It doesn't make anyone "more or less" of whatever sex they're categorized as, but these examples illustrate the complexity of the underlying system. The simple fact is that “male” and “female” labels aren’t always very predictive or relevant when being applied to individuals. Not every “male” has a penis or a prostate or is capable of reproduction, and not every “female” has a uterus, ovaries, or is otherwise capable of reproduction. Humans are more than their reproductive capabilities and simple labels such as "male" or "female" can't fully describe those aspects. Reproduction is not always relevant.

> Your comment about "drawing an arbitrary line" doesn't really fit with how biologists see this either…

Yes, when biologists are abstractly talking about reproduction, individual variation isn’t very relevant. They’re not even talking about sterile individuals. Broadly applying those types of generalizations to individuals isn’t helpful.

> Going way back upthread, this was originally about fairness in sport, male physiological advantage, …

You’re making several pretty big logic leaps in here. Let’s try to sort this out.

First, sport isn’t about reproduction. That’s irrelevant, so please stop trying to argue that gamete size has anything to do with sports. So why do we divide sports into "men" and "women" if reproduction isn't relevant? It's because you've correctly seen that sometimes there's physical, measurable differences between the two groups and we as a society want sports to have some aspect of "fairness." There’s a lot to unpack here, though and you’ve made several incorrect assumptions.

“Male physiological advantage” is an incorrect blanket assumption. Where is the “male physiological advantage” in sharp shooting? Olympic Skeet wasn’t separated by gender from 1968 until 1992, when Zhang Shan from China won the gold metal. After that it’s been divided by sex. Some sports are split by gender for different cultural reasons, and yes, in some sports men as a group tend to be much taller and have advantages in certain areas, but this isn’t as universal as you seem to think. Lots of transphobic people tend to focus on trans women in sports, but they’re dead silent on trans men doing fairly well in the Olympics. There are several examples in basketball, wrestling, swimming etc.

> he seemed to think there are medical interventions that can be performed on humans that convert males to female, which is not the case

There is so much variation in human sexual development, as discussed with intersex, that there honestly doesn’t need to be much “medical intervention.” There is a lot of overlap between the sexes, and the fact that it’s actually so hard to define a criteria to separate them, makes this all easy to understand. And that’s where gender comes in. Gender itself is largely a social construct, so we’re pretty flexible on how we define it. Basically it’s pretty easy to see that it’s a real phenomenon and as scientists, we would like to document and discuss this real phenomenon.

> Then you commented stating that sex is a spectrum. This is typically introduced into an argument to try to bolster the claim that it is possible for humans to change sex, …

Sexual development in humans is hopefully by this point fairly obviously a spectrum. Human intersex exists in many different forms. In general, sports have nothing to do with reproduction, so that’s largely irrelevant. However, we as a society would like to make playing sports generally “fair” and there are general, measurable differences between men and women, and yes, sometimes that does mean men have a physiological advantage over women in certain sports. Scientists have already looked into this, and they determined that after 2 years of hormone therapy transwomen are fairly hard to distinguish from the natural variation in ciswomen for all their metric. That’s why there have been rules in place. I’m actually not sure what the rules are for transmen, but the fact that they’re showing up to the Olympics means that they’re probably doing okay.

> So that leads into another issue of why this "sex is a spectrum" idea has been introduced to the world at large. …

Hopefully you have a better understanding of what I mean now. You’re literally using the terms as a spectrum by talking about intersex and using it to describe hermaphrodite species. Being able to apply binary labels to a system doesn’t make it “binary,” what actually matters is the criteria and the output when we’re talking about models. Does that make sense? By calling it a “spectrum,” I’m not actually introducing some new niche model, the fact that I referenced a textbook should make this clear, I’m just saying the data isn’t “binary” and that should be obvious alone from being able to describe so many different species with two terms.

Hope this clears things up!