Although the view that sex is a spectrum, and that there are more than two biological sexes in humans and other species, is still prevalent among the woke, others are realizing that sex in humans (and nearly every other species of plant and animal) is indeed a binary, with a tiny fraction of exceptions in humans. These include individuals with “differences in sex determination” (DSD) and almost nonexistent hermaphrodites. Estimates of exceptions in our species range from 0.02% to 0.005%.
The rise of the “sex is a spectrum” notion is due solely to the rise of gender activism and to people who identify as nonbinary or transgender. But gender is not the same thing as biological sex: the former is a subjective way of feeling, while the latter is an objective fact of biology based on a binary of gamete types.
I personally don’t care if someone identifies as a member of a nonstandard gender, but I do care when people like Steve Novella, who should know better, argue that biological sex is not a binary but a spectrum. In fact, there are far more people born with more or fewer than 20 fingers and toes than are born as true intersexes, yet we do not say that “digit number in humans is a spectrum.”
It’s a shame that many of those who claim that sex is a spectrum are biologists who recognize the sex binary and its many consequences, like sexual selection. The misguided folks include the three main scientific societies studying evolution, who issued a statement that biological sex was a spectrum, and further that this was a consensus view. (Their original statement is archived here.) The societies then took down their claim when other biologists pointed out its inanity (see here, here, and here). And it’s not only biologists who recognize the ideology behind the claim that sex is a spectrum; the public does, too. NBC News reported this in 2023 (note the conflation of sex and gender):
A new national poll from PRRI finds Americans’ views on gender identity, pronoun use and teaching about same-sex relationships in school deeply divided by party affiliation, age and religion.
Overall, 65% of all Americans believe there are only two gender identities, while 34% disagree and say there are many gender identities.
But inside those numbers are sharp differences. Fully 90% of Republicans say there are just two genders, versus 66% of independents and 44% of Democrats who believe the same
Sadly, if you’re on the side of truth in this debate, at least as far as the number of sexes go, you’re on the side of Republicans. So it goes. Further, Americans and sports organizations themselves are increasingly adopting the views that trans-identified men (“transwomen,” as they’re sometimes called) should not compete in sports against biological women. This is from a 2025 Gallup poll.
Sixty-nine percent of U.S. adults continue to believe that transgender athletes should only be allowed to play on sports teams that match their birth sex, and 66% of Americans say a person’s birth sex rather than gender identity should be listed on government documents such as passports or driver’s licenses.
Thus, although wokeness is like a barbed porcupine quill: easy to go inside you but hard to remove, I’m pretty confident that the claim of a biological sex spectrum will eventually decline even more. But there are still some ideologues who twist and misrepresent the facts to argue that there are more than two sexes. (The argument centers on humans, of course.) One of these is Princeton anthropologist Agustín Fuentes, who has written several papers and a recent book arguing for the human sex spectrum. I’ve pushed back on his arguments many times (see here), and wrote a short review of his book Sex is a Spectrum, a book that should be read with a beaker of Pepto-Bismol by your side. There’s another and better critical review of Fuentes’s book by Tomas Bogardus, here, which Bogardus has turned into his own new book, The Nature of the Sexes: Why Biology Matters.
This post is just to highlight another critical review of Fuentes’s book and his views on sex, one written by Alexander Riley and appearing at Compact. You can get to a paywalled version by clicking on the title below, but a reader sent me a transcript, and I’ll quote briefly from that below.
A few quotes (indented). I don’t know how readers can access the whole review without subscribing:
Fuentes, an anthropologist who has extensively studied macaques, begins with a primer on the evolution of sexual reproduction in life on the planet. To show how “interesting” sex is, he offers the example of the bluehead wrasse, a fish species in which females can turn into males in given ecologies. The example, he says, is “not that weird” in biology.
But the reality is that species like this one most definitely are weird, not only in the animal kingdom, but even among fish, who are among the most sexually fluid animals. Among fish, the number of species that are sexually fluid in this way is perhaps around 500 … unless you know that there are approximately 34,000 known fish species. In other words, even in the most sexually fluid animals, transition between male and female by one individual can happen in only 1.5 percent of the total species. What Fuentes describes as “not that weird” is certainly highly unusual. [JAC: note that switching from male to female or vice versa does not negate the sex binary.]
This sleight of hand is typical of Fuentes’s handling of evidence. He attacks a classic argument in evolutionary biology that differences in male and female gametes (sperm an eggs, respectively) explain many other differences between the two sexes. In short, because eggs are much costlier to make than sperm, females have evolved to invest more energy in the reproductive chances of each gamete compared to males. This bare fact of the gamete difference means, according to the Bateman-Trivers principle, males and females typically develop different mating strategies and have different physical and behavioral profiles.
The distortion below is typical of ideologues who promote Fausto-Sterling’s data even when they know it’s incorrect:
Fuentes notes that what he calls “3G human males and females,” that is, those individuals who are unambiguously male or female in their genitalia, their gonads (the gland/organ that produces either male or female gametes), and genes, do not make up 100 percent of human individuals. He goes on to suggest that at least 1 percent of humans, and perhaps more, do not fit the 3G categories. This is a claim unsupported by the facts. The citation he links to this claim is an article by biology and gender studies professor Anne Fausto-Sterling. The claim made by Fausto-Sterling about the percentage of those who are intersex has been thoroughly debunked. She includes a number of conditions in her category of intersex (or non-3G) that are widely recognized as not legitimately so classified. One such condition (Late Onset Congenital Adrenal Hyperplasia, or LOCAH, a hormonal disorder) makes up fully 90 percent of Fausto-Sterling’s “intersex” category. Individuals with LOCAH are easily classed as either male or female according to Fuentes’ 3Gs, and nearly all of them are able to participate in reproduction as normal for their sex. The percentage of those who are actually outside 3G male or female classes is likely around 0.02% percent, which means that 9,998 out of every 10,000 humans are in those two groups.
What’s below shows that trans-identified men do not become equivalent to biological women when they undergo medical transition:
Transwomen are much more likely to exhibit behaviors of sexual violence and aggression than women. A 2011 study showed clearly that even male-to-female transsexuals who had undergone full surgical transition, and who therefore had undergone hormone therapy to try to approximate female hormonal biology, still showed rates of violent crime and sexual aggression comparable to biological males. They were almost twenty times more likely to be convicted of a violent offense than the typical female subject. This is reason enough to keep individuals who have male hormonal biology out of spaces in which they interact closely with semi-clad girls and women.
And Riley’s conclusion:
The fact that Fuentes can make such ill-founded claims without fearing serious pushback is an indication of how captured academic culture is by the ideology behind this book. A healthy academic culture would not so easily acquiesce to political rhetoric masquerading as science.
Yes, anthropology has been captured—especially cultural anthropology—and, as I said, even some biologists have gone to the Dark Side. I have nothing but contempt and pity for those who know that there are two sexes but twist and mangle the facts to conform to the woke contention that the sexes can be made interchangeable. But I should add the usual caveat that, except for a few exceptions like sports and prisons, transgender people whould be given the same rights as everyone else.
Another sign of people rejecting the “sex is a spectrum” claim is that Fuentes’s book didn’t sell well. Despite coming out less than a year ago. it’s now #301,447 on Amazon’s sales list, and has only 25 customer ratings, totaling 3.8 out of 5 stars. It didn’t exactly fly off the shelves.
Here are two Amazon reviews by savvy readers (note: none of the reviews on Amazon are by me):
PCC(E) : “But there are still some ideologues who twist and misrepresent the facts to argue that there are more than two sexes. ”
As the ideologues repeat themselves, so I take the opportunity to repeat the following :
“Ideological subversion [..] or psychological warfare [..] change(s) the perception of reality [..] to such an extent that despite the abundance of information, no one is able to come to sensible conclusions in the interests of defending themselves, their families, their community and their country. It’s a great brainwashing process, which goes very slow [..] ”
-Yuri Bezmenov
Interview 1983 or 1984
Many copies available, e.g: https://youtu.be/0fx1BYwCwCI?si=Bqd5UmnnBlRMxrGq
Fortunately, I’d note, there are still some sensible conclusions to be found.
But that does not happen by accident.
Or, phrasing this slightly differently, they should have exactly the same rights as everyone else. And indeed they do! That is, a trans-IDing male has exactly the same rights as a cis-IDing male. He does not lose any right by IDing as trans.
It’s the fact that he doesn’t necessarily gain some rights that trans activists want him to that is the contentious issue.
Agreed. The “trans” women can compete against (or be imprisoned with) the other males. Alternatively, all the males should be allowed to compete against (or be imprisoned with) females, not just the males who say a few magic words.
“I personally don’t care if someone identifies as a member of a nonstandard gender”
I try to practice what our host preaches. One helpful mental trick when I meet people around my university campus who have gender non-conforming presentation is to think of their traits as just fashion choices. “Ok, he’s wearing pigtails and a skirt, whatever.” I try to think of the “trans” kids as playing acting, like the folks dressed as anime characters, the goths, the gym bros, and the varsity athletes. Helps reduce my tendency to read their minds and ascribe ungenerous claims or attitudes to people based only on their superficial appearance.
This is helpful for me because I know and teach a lot of “trans” students, and they ~all turn out to be troubled, confused, often autistic, sometimes obviously gay, but overall fine individuals just trying to learn and get a degree. It’s the “trans” (or, worse, the “non-binary”) adults around my university who, like Fuentes, make unsupported claims about themselves and about the biology of human sex, and threaten those who disagree with their misguided views.
One of the few organizations that is tackling this issue and making sensible standards is USA Boxing. Originally they did not allow trans men (biological women) to compete because of the potential for injury. Now they have specific requirements for trans athletes. Here’s their requirements: https://assets.contentstack.io/v3/assets/blteb7d012fc7ebef7f/blt1b2d301085363e4d/6942d42fb9ac8ad6decbc1ca/USA_Boxing_Sex_Eligibilty_Policy.pdf
They differentiate trans athletes who have completed genital reassignment surgery and hormone replacement to those who haven’t. This is a more sensible way to approach the subject, rather than “anyone who says they are a women, is a woman”. I think the difference between people who identify as trans and those who have followed all the necessary procedures to BE trans is a huge distinction. Biological women shouldn’t have to tolerate “people with penises” (as Bill Maher calls them) in women’s prisons, breastfeeding classes, therapy groups, or gym saunas. I really think there are stages to being trans and they should all be completed to demonstrate a person’s true commitment to their feelings.
Amy, with respect, I think this is misguided. Men who medicalized their “trans” identity are still male. This review shows such males retain their athletic performance advantage over females, testosterone suppression or genital surgery notwithstanding.
https://doi.org/10.1007/s40279-020-01389-3
From the abstract, “Males enjoy physical performance advantages over females within competitive sport…Here, we review how differences in biological characteristics between biological males and females affect sporting performance…We report that the performance gap between males and females…is more pronounced in sporting activities relying on muscle mass and explosive strength, particularly in the upper body…[T]he muscular advantage enjoyed by transgender women is only minimally reduced when testosterone is suppressed.”
And sorry for overcommenting.
Thanks for the comment Mike. I was trying to make the point that trans people need to reach a higher threshold than “that’s how I feel” in order to be acknowledged in their trans identity. And that’s what USA Boxing is doing. Of course in polite company, I would also acknowledge their chosen identity and I agree with you: I see them as play acting.
Amy, the USA Boxing policy you linked to absolutely prohibits birth men from boxing against birth women, no exceptions. It reserves the right to test any registered boxers for maleness defined as SRY gene plus testosterone sensitivity. The policy explicitly does not make any reference to sex reassignment surgery or androgen suppression as an exemption or accommodation. Under such an inclusive formulation a female boxer would eventually die from being punched in the face by a man.
Sport (especially contact/combat sport) is the worst possible women’s space to let men enter if they have “done the work” or “committed to their feelings” with surgery and androgen suppression. In a women’s prison or a bathroom, you can at least punish the man if he assaults a woman. Theoretically he could be physically harmless (although degrading) to women if the likelihood of punishment was certain and swift. In boxing, the whole idea is to punch her in the face. If he killed her he wouldn’t be punished if it was within the rules.
I don’t know if there is any staged setting where any kind of man should ever be recognized as a sort-of woman just because he’s “done the work” to “demonstrate [his] true commitment to [his] feelings.” No matter what a man does he’s still a man. But sport is certainly not one of those where he could be a woman. That’s not what you meant, surely?
I must have read rules that were superseded. Sorry.
Yes, good point.
I think it really should include anything that applies to a single sex space. This includes bathrooms. Women are after all more vulnerable in these spaces. It also allows for children to be safer especially young boys when they wish to go into male toilets but not sufficiently savvy to do a risk assessment. Most mothers would agree to this principle.
Another thing that these men should not be included in is prizes awards scholarships etc that are available only for women. It is just another form of cheating.
The rights they are demanding to be honoured has NEVER been elaborated or explained and that is the nub of the problem.
The overemphasis within the education system has created a myriad of problems and in some cases the material is so sexually explicit that adults refuse it to be read aloud in the confines of grownups discussions. This is not a sustainable movement.
Trans rights are fine but it should not be at the expense of women and children’s rights
On a side note a detransitioner has been awarded $2 million against her doctor, expect more of the same.
https://x.com/fem_mb/status/2017425438155362516?s=20
Trans rights inevitably conflict with women’s rights. If a right or perq is awarded to a woman, it is worth less to her if she has to share it with men who call themselves women. You will have to choose, or get rid of special women’s rights altogether (like scholarships and preferential hiring.)
Children don’t have rights per se, but they have to be protected from harm, which trans rights also work against.
As exasperating as this attack on the sex binary is, it too shall pass. At some point, sex will “again” be a binary, and the focus will shift from sex to gender—where gender is “a subjective way of feeling,” as you say. Gender activists are hurting their own credibility by denying biological reality. My hope and expectation is that they will soon change course.
It started out as “well of course transwomen are male (and transmen are female) — nobody is arguing about what sex they are! They know. This is about gender.”
That, however was dropped when it became obvious that ppl wouldn’t be allowed to pick where they wanted to change, go to the bathroom, or enter any other single-sex space as long as it was okay to talk about single-sex spaces. Sex had to become so fraught with confusion and contradiction that it was more reasonable and easy to believe that “men” and “women” are genders, and “single-sex space” a laughable anachronism.
If you are trying to prove that some horses could be cows, you could
* Try to create obfuscation about the concept of a biological species
* Pretend that you didn’t mean horses can be cows “biologically”, but in some handwavy metaphysical sense.
Trans ideologues are trying the equivalent of both. Attack on biology and “gender identity” foofoo.
The above poll data consistently tested for views on gender, rather than biological sex. But of course there will always be Great Confusion on the supposed differences between those those terms. I tried to look at polls on whether sex is a spectrum, and got this Google AI result:
Scientific Consensus: A 2024 poll of British scientists found that 58% believe sex is a binary, while 29% believe it is a nonbinary spectrum. Many scientists argue that biological sex is fixed based on gamete production, while others contend that intersex individuals and varied phenotypes make sex a “bimodal” or spectrum-based system.
Public Perception of Sexuality: A 2019 YouGov poll indicated that 46% of Americans believe sexuality is a scale, while 38% believe it is not.
Generational Divide: Younger generations (Gen Z and Millennials) are less likely to view sexuality as strictly binary compared to Baby Boomers.
Political Polarization: Views on sex and gender are highly partisan, with Democrats far more likely than Republicans to accept that gender can differ from assigned sex.
Not an encouraging result! But again, there is that Great Confusion out there about sex vs gender, even among academics. If it ever was useful, the gender term is worthless now.
[TAC: note that switching from male from female or vice versa does not negate the sex binary].
Indeed, uttering that sentence AFFIRMS the sex binary. What else could one mean by calling the clownfish male before the transformation and female afterwards? Clearly when we are not speaking of a change in the fish’s psychological gender identity or preferred pronouns. We are using the words “male” and “female” in their proper meaning to refer to reproductive function and structures, specifically gametes. The “trans” nature of a clownfish is VERY different than the “trans” nature of Lia Thomas.
Maybe the poor clownfish is “on the spectrum” when “they” is in the middle of “transitioning” from male to female or vice-versa?
” …yet we do not say that “digit number in humans is a spectrum.”” But I have just formed the World Professional Association for Trans-Digital Health; we will lobby anthropology and medical associations for the cause of digit-Diversity, citing your point about digit number in humans.
Seriously, we need sociological investigation of the capture of professional organizations by faddish delusions: something like histories of the Children’s Crusade, the Dutch Tulip mania, and more recently the Recovered Memory Therapy episode.
The book Extraordinary Popular Delusions and the Madness of Crowds is an older but well known book that deals with this stuff, including Tulip Mania.
Check out Alice Dreger’s book, Galileo’s Middle Finger, which, as Wikipedia describes it, “explores the relationship between science and social justice by discussing a number of scientific controversies. These include the debates surrounding intersex genital surgery, autogynephilia, and anthropologist Napoleon Chagnon’s work.”
https://en.wikipedia.org/wiki/Galileo%27s_Middle_Finger
I just finished reading Alex Byrne’s book, ‘the Trouble With Gender’, which appears to be a highly effective rebuttal of this Fuentes book ( which I haven’t read ). But Amazon Melanialand ranks it at #1 000 000 in sales rank, well behind Fuentes! Based on the bibliography and footnotes, Byrnes has read v widely indeed on the subject, including many of the scientific and popularised books on sex differences in the brain. He basically believes the word ‘gender’ is too confusing, and the sex-gender distinction largely spurious.
Ramesh 98% male, 2% Denisovan indeterminate sex
I would go a bit further than PCC(E). Sex is always binary, in my opinion. Some (quite rare) humans have both sexes (hermaphrodites). Some humans (quite rare) are thought to be one sex when they are really another (for example, Imane Khelif and Caster Semenya). Some humans (quite rare) have no sex. In my opinion, DSDs are not rare exceptions to the sexual binary.
This. I just posted a longer version of the same point. DSDs are defects (typically) caused by deleterious mutations. There are other deleterious mutations that can effect any characteristic of an organism- this is special pleading for that class.
I had the same thought. It might count as third sex if a person is a fully functioning hermaphrodite, i.e., able to produce both types of gametes. I’m not aware of any such cases ever existing, though; and it would still be somewhat complicated, since sex is usually a species-level trait, unaffected by bizarre outliers.
Classifying either Semenya or Khelif as male is unwarranted, by the way. The former has a DSD with female genitalia and internal testicles, and there’s no real evidence of the latter having any condition at all.
I have found no cases in which a person produces both types of viable gametes.
Strictly speaking you are correct. The sex of both those athletes (and the medical evidence to diagnose it) is part of their confidential medical records and can’t be disclosed to anyone without their consent, or according to law. If there’s no “real evidence” it’s because the athlete hasn’t released it.
Athletic governors aren’t trying to determine what sex an athlete “really” is. Rather, they need only verify that all athletes seeking to compete in women’s events satisfy the eligibility criteria the governing body sets down. An athlete who says she is a woman and accordingly applies to register for women’s events must not be:
Testing (with the athlete’s consent as a condition for permission to register) is aimed at detecting any of these three criteria for disqualification. Practically speaking, detection of an SRY gene, plus assays for testosterone in the separate anti-doping regimen, will cause rejection on any of these three counts. (An athlete found to have an SRY gene who is sure she is a woman can appeal for supplementary lab testing plus medical exam if appropriate and if she consents to it. If she is diagnosed with complete androgen insensitivity she will be granted a waiver to compete.)
All this is confidential as far as other competitors and the general public are concerned. The larger community doesn’t need to know that any named athlete is competing under a “sex” waiver. It just needs to have confidence that all the competitors it cheers on are qualified under the rules and none are ringers or dopers. Any athlete disqualified for any reason can say publicly whatever s/he likes.
In the UK, Canada, and the Netherlands, official professional groups advised caution about Recovered Memory Therapy. Thus, the RMT enthusiasts achieved less institutional capture than the more recent enthusiasts of anything with the magic word “Affirmative” attached to it. I wonder if this failure of RMTism had something to do with the notorious legal cases involving RMT. If so, that lesson might apply, in time, to our present day instances of faddish delusion movements.
Here’s an archaeologist who read the book and is not impressed. I thought he did a good takedown of the book and as far as I know he has not received any blowback for it. From the intro: “What I learned: Unfortunately, pseudoscience exists in other realms beyond pseudoarchaeology.”:
https://www.archaeologypodcastnetwork.com/pseudo/172
After dissecting this ridiculous book, he very strongly recommends reading Jerry’s book as counter-balance.
I’m still disturbed that they don’t realize the implications of their logic with regard to DSDs. Female and male are functional definitions. If an individual can produce offspring they do so by producing one of the two gamete classes. If not, we can typically tell what sex they are by their gonads (and if they don’t have differentiated gonads they are not relevant to a definition of the sexes).
The logic of saying that DSDs disprove the binary would lead to not being able to make any statement about any group of organisms, since there exist mutations (or accidents) that can alter any characteristic. It would therefore render systematics or comparative biology impossible.
To prove sex is not binary, one would need to show a group of individuals that sexually reproduce without producing oocytes or sperm. No such group exists in mammals.
There is actually some humor associated with this topic. Fuentes authored an article in Scientific American (May 2023) titled “Here’s Why Human Sex Is Not Binary”. The humor is that the associated image shows the sexual binary.