I wish I had a happier post for number 30,000, but you’re stuck with this one. However, it’s in line with the kind of stuff I’ve been writing about for a while, so it’s appropriate.
Today we must deal with a letter from the Presidents of three organismal evolution and ecology societies (The Society for the Study of Evolution, American Society of Naturalists, and the Society of Systematic Biologists), a Diktat declaring that biological sex is not binary, exactly as they did in 2018 (same societies, almost the same statement). Both letters were also responses to statements by the U.S. government headed by Trump, taking issue with the government’s position that sex is binary. HHS incorrectly used genitalia as an earlier criterion for what was binary, but Trump’s new Executive Order uses an accurate definition of sex, one based on whether an individual’s reproductive apparatus is set up to produce large immobile or small mobile gametes. (I guess I should make the requisite disclaimer that while I agree with much but not all of Trump’s statement, that doesn’t mean I endorse Trump!)
My critique of the 2018 statement is posted at this site. I took the position that scientific societies shouldn’t take ideological stands unless they are attacking an ideology that damages the mission of the society itself, and are making a statement that corrects an incorrect but widespread view. Well, this again applies here: these three societies are attacking a biological fact: the binary definition of biological sex, something well within the ambit of biology societies. The problem is that, as in 2018, the three societies are using misleading and false arguments to show that biological sex is a spectrum. Further, as in 2018, the motivation for this statement does not appear to be a scientifically-based attempt to correct government misinformation, but rather seems to be ideological. In fact, biologists have recognized sex as binary (with a few very rare exceptions) since the late nineteenth century, and have based the binary conclusion on the fact that all animals and plants produce two types of gametes, with no intermediates (see below for references).
The desperate attempt in this letter, and the one in 2018, to show that sex is a spectrum intends, I think, to buttress those people who either feel they don’t belong in one of the two sexes, are transsexual (a behavior that assumes two sexes) or feel that they are somewhere in between—or even members of neither sex. But the attempt is misguided, for, as I’ve said repeatedly, morality, as The Naturalistic Fallacy and The Appeal to Nature Fallacy argue, should not be strongly based on biological reality. Observing nature does not tell us what is right or wrong, or specify how we should behave towards others.
However, the 2018 and present letters, instantiate a third falacy—what Luana Maroja and I call the “reverse naturalistic fallacy” described in our Skeptical Inquirer paper (bolding is mine below):
Both fallacies lead to the same errors. First, if we condition our politics and ethics on what we know about nature, then our politics and ethics become malleable to changes in what we discover about nature later. For example, the observation that female bonobos rub each other’s genitals as a bonding behavior has been used to justify why human homosexuality is neither offensive nor immoral. Bonobo behavior is, after all, “natural.” (Similar same-sex behaviors have been reported in many species and have been used to the same end.) But what if no such behavior had been seen in any nonhuman species? Or what if the bonobo observation was shown to be wrong? Would this make homosexual behavior immoral or even criminal? Of course not, because enlightened views of homosexuality rest not on parallels with nature but on ethics, which tells us that there’s nothing immoral about consensual sex between adults.
Second, we must realize that many behaviors that are “natural” because they’re found in other species would be considered repugnant or immoral in our own. These include infanticide, robbery, and extra-pair copulation. As one of us wrote, “If the gay cause is somehow boosted by parallels from nature, then so are the causes of child-killers, thieves and adulterers.” But we don’t really derive our morality or ideology from nature. Instead, we pick and choose those behaviors in other species that happen to resemble a morality we already have. (People do exactly the same thing—ignoring the bad behaviors and lauding the good ones—when they pretend to derive morality from religious texts such as the Bible.)
All the biological misconceptions we’ve discussed involve forcing preconceived beliefs onto nature. This inverts an old fallacy into a new one, which we call the reverse appeal to nature. Instead of assuming that what is natural must be good, this fallacy holds that “what is good must be natural.” It demands that you must see the natural world through lenses prescribed by your ideology. If you are a gender activist, you must see more than two biological sexes. If you’re a strict egalitarian, all groups must be behaviorally identical and their ways of knowing equally valid. And if you’re an anti-hereditarian—a blank slater who sees genetic differences as promoting eugenics and racism—then you must find that genes can have only trivial and inconsequential effects on the behavior of groups and individuals. This kind of bias violates the most important rule of science, famously expressed by Richard Feynman: “The first principle is that you must not fool yourself—and you are the easiest person to fool.”
Thus the latest letter, like the earlier one, is apparently written to try to convince people that in reality sex is not binary in nature, thereby buttressing gender-activist ideology. It is not meant to clarify mistaken biological views. In fact, the letters muddy the waters by presenting a misguided view of sex and giving it the imprimatur of biological societies. As we’ve learned so often recently, though, what scientific societies and journals say often flouts the truth, intended to be ideological rather than scientific.
The problem, then, is not that the societies are making a political statement about biology. The problem is twofold. First, the societies’ attempt to buttress their biological argument is wrong, involving a lot of misleading assertions—all in three short paragraphs.
Second, the Presidents of the Society say they are speaking not only for the 3500 scientists who belong to their organizations, but also for the majority of biologists, saying that their conception of sex represents a scientific “consensus”. It does not, nor do they know this. They did not poll their members before issuing their statement, and they buttress their argument by citing just two papers, one a very short Scientific American op-ed showing that the development of biological sex is complex and can be derailed by a number of mutations, the other a Nature paper by a freelance science journalist who uses a similar argument: the process of sex determination is “complex.” Indeed it is, but development is always complex, and yet, remarkably, evolution has channeled it into two pathways with similar destinations in all animals and vascular plants, producing, by a variety of developmental processes, two types of individuals in these species, one producing sperm and the other eggs. And that journalist, as you see below, doesn’t support the statement at all! Did they even bother to check that? (h/t: a reader below):
No, not at all. Two sexes, with a continuum of variation in anatomy/physiology.
— Claire Ainsworth (@ClaireAinsworth) July 21, 2017
The best refutation of the letter below is actually Richard Dawkins’s Substack piece on the binary nature of sex (excerpted from a forthcoming essay), “Is the male female divide a social construct or a scientific reality?” I recommend that you read it after you read the letter below. But I’ll give one quote from the piece first, showing Dawkins presenting the “Universal Biological Definition” (UBD) of sex:
It is no idle whim, no mere personal preference, that leads biologists to define the sexes by the UBD. It is rooted deep in evolutionary history. The instability of isogamy [the condition in which all individuals have gametes of the same size], leading to extreme anisogamy [the condition in which individuals have gametes of different sizes, meaning two], is what brought males and females into the world in the first place. Anisogamy has dominated reproduction, mating systems, social systems, for probably two billion years. All other ways to define the sexes fall afoul of numerous exceptions. Sex chromosomes come and go through evolutionary time. Profligate gamete-spewing into the sea gives over to paired-off copulation and vice versa. Sex organs grow and shrink and grow again as the aeons go by, or as we jump from phylum to phylum across the animal kingdom. Sometimes one sex exclusively cares for the young, seldom the other, often both, often neither. Harem systems change places with faithful monogamy or rampant promiscuity. Psychological concomitants of sexuality change like the wind. Amid a rainbow of sexual habits, parental practices, and role reversals, the one thing that remains steadfastly constant is anisogamy. One sex produces gametes that are much smaller, and much more numerous, than the other. That is all ye know of sex differences and all ye need to know, as Keats might have only slightly exaggerated if he’d been an evolutionary biologist.
On to the letter, and I’ll try to be brief since Richard’s piece shows the fallacies inherent in their defense of a “spectrum” of biological sexes. The letter is indented, and you can see the original by clicking the title below:
Policy: Letter to the US President and Congress on the Scientific Understanding of Sex and Gender
President Donald J Trump
Washington, DCMembers of the US Congress
Washington, DCFebruary 5, 2025
RE: Scientific Understanding of Sex and Gender
Dear President Trump and Members of the US Congress,
As scientists, we write to express our concerns about the Executive Order “Defending Women From Gender Ideology Extremism And Restoring Biological Truth To The Federal Government”. That Order states first, that “there are two sexes…[which] are not changeable”. The Order goes on to state that sex is determined at conception and is based on the size of the gamete that the resulting individual will produce. These statements are contradicted by extensive scientific evidence.
Scientific consensus defines sex in humans as a biological construct that relies on a combination of chromosomes, hormonal balances, and the resulting expression of gonads, external genitalia and secondary sex characteristics. There is variation in all these biological attributes that make up sex. Accordingly, sex (and gendered expression) is not a binary trait. While some aspects of sex are bimodal, variation along the continuum of male to female is well documented in humans through hundreds of scientific articles. Such variation is observed at both the genetic level and at the individual level (including hormone levels, secondary sexual characteristics, as well as genital morphology). Beyond the incorrect claim that science backs up a simple binary definition of sex, the lived experience of people clearly demonstrates that the genetic composition at conception does not define one’s identity. Rather, sex and gender result from the interplay of genetics and environment. Such diversity is a hallmark of biological species, including humans.
We note that you state that “Basing Federal policy on truth is critical to scientific inquiry, public safety, morale and trust in the government itself”. We agree with this statement. However, the claim that the definition of sex and the exclusion of gender identity is based on the best available science is false. Our three scientific societies represent over 3500 scientists, many of whom are experts on the variability that is found in sexual expression throughout the plant and animal kingdoms. More information explaining why sex lies along a continuum can be found here, under the Education and Outreach tab. If you wish to speak to one of our scientists, please contact any of the societies listed below.
Carol Boggs, PhD
President
Society for the Study of Evolution
president@evolutionsociety.orgDaniel Bolnick, PhD
President
American Society of NaturalistsJessica Ware, PhD
President
Society of Systematic Biologists
president@systematicbiologists.org
Oh dear; what a thicket of misguided argumentation we must make our way through here! Let’s take it paragraph by paragraph.
The first paragraph simply denies that there are two sexes, with sex defined by gamete size. These contentions, they say are contradicted by “extensive scientific evidence”. But they cite only two papers supporting that, throwing out a number of traits connected with sex but not part of the UBD, a definition that goes at least as far back back as Robert Payne Bigelow in 1894. For a list of gamete-based definitions from different eras, see this paper by Carlos Y. Fuentes (pdf here); the article is in Spanish but should self-translate into English. To check a more recent book, I just pulled the second edition of Doug Futuyma’s textbook Evolution on my shelf, whose various editions I taught from at Chicago. Sure enough, on p. 389 I find this:
Most sexually reproducing species have distinct male or female sexes, which are defined by a difference in the size of their gametes (ANISOGAMY). In ISOGAMOUS organisms, such as Chlamydomonas and many other algae, the uniting cells are the same size; such species have mating types but not distinct sexes.
I’ve pointed out before that the sex binary applies to all animals (including of course us) and all vascular plants, but not to protists, algae, and some fungi. But the UBD of course centers on humans, not algae or fungi, for humans are the object of the letter below. (They do note that the trait diversity that produces a sex spectrum applies to all biological species!)
The second paragraph can be addressed by Dawkins’s excerpt above: it mentions a lot of traits associated with biological sex that show variation, but these are not part of the UBD itself. Let me repeat his words again:
All other ways to define the sexes fall afoul of numerous exceptions. Sex chromosomes come and go through evolutionary time. Profligate gamete-spewing into the sea gives over to paired-off copulation and vice versa. Sex organs grow and shrink and grow again as the aeons go by, or as we jump from phylum to phylum across the animal kingdom. Sometimes one sex exclusively cares for the young, seldom the other, often both, often neither. Harem systems change places with faithful monogamy or rampant promiscuity. Psychological concomitants of sexuality change like the wind. Amid a rainbow of sexual habits, parental practices, and role reversals, the one thing that remains steadfastly constant is anisogamy. One sex produces gametes that are much smaller, and much more numerous, than the other. That is all ye know of sex differences and all ye need to know, as Keats might have only slightly exaggerated if he’d been an evolutionary biologist.
And of course we do see variation in sex organs, chromosomes, behavior, and so on, as well as “the lived experience of people”, which has nothing to do with any biological definition of sex. (What is the “lived experience” of sea urchins, foxes, or gingko trees, that would affect the binary nature of sex in those species?) In humans, the frequency of exceptions to the sex binary lies between 1/5600 individuals and 1/20,000 individuals. As I’ve said, that’s as close to a binary as you can get.
The authors also say this:
Scientific consensus defines sex in humans as a biological construct that relies on a combination of chromosomes, hormonal balances, and the resulting expression of gonads, external genitalia and secondary sex characteristics. There is variation in all these biological attributes that make up sex.
I have no idea what a “biological construct” is! What is the consensus about the meaning of that term?
The argument proceeds to cite a number of factors associated with sex in some but not all species, but, as Dawkins notes, these traits do not partake in the UBD noted by biologists well before we learned about chromosomes or hormones.
The authors fail to address this important question: if sex is defined by where an organism is positioned along dozens of variable axes, like hormone titer, lived experience, external genitalia, sex chromosomes (many species don’t have these), and other secondary sex traits (there’s a reason they’re called “secondary”!), then how do we determine what sex an individual is? It would have to be some kind of combinatorial, multifactoral analysis that takes all these factors into account. And of course it would result in the delineation of a gazillion sexes within many species—perhaps an infinite number in humans! Is that what the authors really believe? If they say they are “male,” for example, how do they know that?
And yet I’m sure that all of the authors of this letter, if they work on animals or plants, would use the terms “male” and “female” without defining them. For example, ASN President Daniel Bolnick, who works on stickleback fish, also sells them from his lab’s “stickleback stock center”. Below are the going prices. Note that they sell ony two sexes of stickleback: male and female. Why aren’t there more? Aren’t there sticklebacks with a lived experience that aren’t either male or female? How does Bolnick define these sexes and why aren’t there more of them?
I see this is running long, so I’ll make just two more points.
First, the spectrum of sex and the denial of the UBD is said not just to apply to humans, but to all species! From paragraph two of the letter (my bolding):
Beyond the incorrect claim that science backs up a simple binary definition of sex, the lived experience of people clearly demonstrates that the genetic composition at conception does not define one’s identity. Rather, sex and gender result from the interplay of genetics and environment. Such diversity is a hallmark of biological species, including humans.
What? All biological species have the kind of diversity that effaces the sex binary, so they must not participate in the UBD, either? Did the authors realize what they were saying? Is sex a spectrum in elephants, possums, aardvarks, cougars, and so on?
Finally, note that the paper repeatedly emphasizes the authority of their societies, as if they were speaking for all their members. But their members were not polled on this (I’ve asked some), and so the statements must have come from the Presidents themselves or more likely the small board of officers of the societies. It is a Diktat from on high, and the implied unanimity is false. Some members I’ve talked to in the last few days absolutely disagree with the statement and are even offended that they are implicitly characterized as agreeing that sex is non-binary. Nor have several people I’ve talked to discerned a “scientific consensus” that sex is somehow defined by combining a number of traits in a multifactoral way.
The statement below should and will offend the many members of these societies who do see sex as binary:
However, the claim that the definition of sex and the exclusion of gender identity is based on the best available science is false. Our three scientific societies represent over 3500 scientists, many of whom are experts on the variability that is found in sexual expression throughout the plant and animal kingdoms. More information explaining why sex lies along a continuum can be found here, under the Education and Outreach tab. If you wish to speak to one of our scientists, please contact any of the societies listed below.
Well, I could produce a long list of members of these three societies who do not endorse the letter above. (I was once President of the SSE and don’t endorse it, and I have considerable expertise examining the variability of sex expression in fruit flies. In the comments section below you’ll find another former SSE President who disagrees with their new letter as well.)
In the end, what we see here is three prominent organismal-biology societies having been ideologically captured to the point where they will twist and misrepresent scientific fact to buttress an ideologically-based view that sex is a spectrum. These societies and their Presidents should be ashamed of themselves. Scientific truth is not determined by pronouncements of the presidents of scientific societies, however notable these presidents may be. The UBD is one of the great (and few) generalizations in evolutionary biology, a definition that’s been immensely fruitful in understanding things like sexual selection. It’s a great pity that these societies are trying to scupper the UBD simply to buttress an evanescent form of gender ideology.
First, they are wrong. Sex is defined on the basis of anisogamy. Everything else is a characteristic—a correlate—of which type of gamete one has the equipment to produce. There’s a difference between the definition of something and the characteristics with which that something is associated. The letter fails to make this important distinction.
While it’s perfectly OK to be incorrect—a mistake can be corrected—it’s not OK to claim that you are speaking for the entirety of the scientific profession when you are not.
They only imply that they speak for their “3500 scientists, many of whom are experts” … they do not claim it explicitly and one must wonder what the vote might be if the membership were queried.
It’s an institutional statement, and they should have taken a vote before issuing it!
Absolutely. They should have clearly said that this represents their personal opinion and since they did not, it is a clear abuse of their titular positions and all three should be removed.
It’s a sleight of hand employed in an effort to garner credibility.
I think that this is a perfect 30,000th post as it represents an example of why WEIT is so valuable to me as a general type of informative post and also in particular to me as a non life-science person. Thanks for this website.
+1
+1
Agree.
yes! I would also like to hang on to reality, despite all of this.
Reality — accept no substitutes.
Agreed. Also wanted to say thanks for the link to Jerry’s 2018 post, where Ken Kukec commented liberally (ha ha). I of course never met Ken but valued his voice here. RIP.
Yes Mike. I think of Ken often as matters of law show up on WEIT and really miss him.
Yes. Perfect 30,000th post. Thanks to Coyne and Dawkins for telling it like it is on this. Denying basic biology for ideological reasons didn’t work for creationism, it didn’t work for Lysenkoism, and it won’t work for the sex denialists either. It could easily lead to disaster, though, as occurred with Lysenkoism.
Yes: evolution, and true liberal politics.
What’s going on in the USA. This is really insane. I am a biologist from Norway and can’t get my head around how ideologically captured organizations in the US are. Can’t they see they destroy the publics trust in science.
They even use the Sex redefined article as “evidence” that sex is not binary. As many of you know by now, Claire Ainsworth was actually asked about this in a twitter post. Here is her answer:
https://x.com/ClaireAinsworth/status/888365994577735680
Again, really insane and I can’t image this would be possible in any professional organizations for biologis in any Euroipean county
Apparently not. Not only that, but it’s this kind of stuff that gets people to vote for Republicans, because everybody can observe that there are two sexes in humans. Deny that and you lose votes.
It’s worse that losing votes.
When they write:
We agree [that truth is critical to scientific inquiry, public safety, morale and trust in the government itself]. However, the claim that the definition of sex and the exclusion of gender identity is based on the best available science is false.
Everyone will indeed see that:
three prominent organismal-biology societies (…) will twist and misrepresent scientific fact to buttress an ideologically-based view
Observing this, what will anti vaxxers think? Every conspiracist will be reinforced in their prejudices, and for once rightly so! This does something worse than losing votes, erodes trust in science.
IMO, the scientists who are defending the spectrum theory of sex should be canceled, once the dust settles.
“Yeah no, didn’t you go out of your way to defend that nonsense? No grants for you!”
And the next time that scientific orgs try to advise the public about best safety practices during the next pandemic, it will not fly as far.
I was recently educated here that it was St. Augustine who made the famous quote, bemoaning how Christians traveling abroad will discredit their cause by telling the locals errant nonsense that they know are not true.
“Usually, even a non-Christian knows something about the earth, the heavens, and the other elements of the world, about the motion and orbit of the stars and even their size and relative positions, about the predictable eclipses of the sun and moon, the cycles of the years and the seasons, about the kinds of animals, shrubs, stones, and so forth, and this knowledge he holds to as being certain from reason and experience. Now, it is a disgraceful and dangerous thing for an infidel to hear a Christian, presumably giving the meaning of Holy Scripture, talking nonsense on these topics; and we should take all means to prevent such an embarrassing situation, in which people show up vast ignorance in a Christian and laugh it to scorn. ”
Sad that we have to agree with that fellow, but we didn’t start this!
To the best of my knowledge, Claire Ainsworth’s tweet is entirely correct. She was asked about this by Dr. Li Qi Huang.
And I can’t understand why Claire Ainsworth doesn’t speak about how her article is being misrepresented again and again.
My guess (and it is only a guess) is that she is keeping quiet to avoid imperiling her commission income stream. A non-economic explanation is she fears that her words would be used by folks she opposes.
(Congrats on 30,000!)
oh yeah! Ditto! Congrats, Dr PCC(e). 30,000. Wow. I hope for many more.
My goodness, such addled and contorted thinking from professional biologists, of all people. It must really vex you and your colleagues, Dr Coyne. I can understand those who have no training in the biological sciences to have some confused ideas about chromosomes, development and such things, but these people? With apologies to Charles Babbage; I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a definition of biological sex.
Thanks for the Babbage reference. Looking it up, the original quote dealt with a demonstrably confused (stupid?) notion put forward by two separate members of Parliament. The historical parallels are just begging to be drawn.
Like Jerry, I too am a former President of SSE, and like Jerry, I too find this societal letter to be quite disturbing on several levels. It does not speak for me.
I gave up my memberships in SSE and SICB over these issues. The final straw was about antiracism not genderism, but both issues are promoted by the same society leadership. At one of the annual meetings a workshop on racism in science was poorly attended by senior researchers, and some of the young black women in the society complained about this on twitter. A prominent older member tweeted his regrets about not being able to attend, and was dogpiled by other members reminding him about the difference between not-racist and anti-racist, implying that he was maybe a little bit racist for not attending the workshop. When I complained to the society leadership about some members calling other members racists on social media, the response was that this is a good thing and members of the org should be calling out the older white guys for not attending workshops and not showing fealty to the cause .
This is why I support Jerry and others arguing against these actions by scientific societies and their journals: one can’t oppose these misguided efforts from inside the org, they can only be criticized from outside. Keep it up.
I too am a former President of SSE and I too am not keen on this letter.
Thanks John and Jerry for speaking up.
I agree that this is a very fitting 30,000th post.
We need to restore ‘institutional neutrality’ to all of our scientific societies.
There’s absolutely no reason for a scientific society to issue a document like this. Nothing is preventing individual members of these societies from banding together as individuals and issuing their own statement, if this is what they believe.
But instead, they want to leverage the society itself to issue a ‘diktat’ that supposedly speaks for all members, in order to pretend that there is some kind of consensus on this issue.
It’s virtue signalling at its finest. Their statement will convince absolutely no one, and it will be counterproductive at best. (Just like Nature’s endorsement of Biden over Trump in 2020 was found to have no effect in persuading people to vote for Biden; instead it just made Republicans distrust scientific institutions more.)
All these societies should follow the Kalven Report and refrain from making statements like this. Like universities themselves, scientific societies should generally be “the home and sponsor of critics, not themselves the critic.” Unless they’ve specifically been commissioned to conduct and study and draft a report, etc.
Well, hey – congratulations on WEIT post no. 30K!
Here’s to principles, clarity, wildlife photography – and so much more – things to be happy about!
Congratulations on number 30,000.
These PCC(E) “blog posts” are maybe a modern version of the Gould and Asimov essays that I used to look forward to once a month. Thank you.
Biological sex, with eggs and sperm, is not just in plants and animals. The trait also extends into the so-called Protista (although this is not a monophyletic group). It’s well known that multicellular algae have species with males (making sperm) and females (making eggs), and also hermaphrodite species that make both (and they don’t make intermediate gametes). I wish I had more comprehensive knowledge on the subject, but in looking up some things I was surprised to learn that the trait was not entirely confined to multicellular species. I thought it was! The large group of flagellated obligate parasites called Apicomplexans have a complex life cycle that include a sexual cycle where they put out large immobile ‘macrogametes’, and flagellated mobile ‘microgametes’. I have not idea why they aren’t simply called egg and sperm, but anyway that was interesting.
The single-called Protozoa of the genus Plasmodium, which cause malaria, display anisogamy as well. In the blood of the vertebrate host you see microscopically distinguishable male and female gametocytes that formed through meiosis from the asexual cells, each one contained in an erythrocyte. The size difference is not conspicuous at this stage but in the mosquito’s stomach, the male micro-gamete converts most of its volume into flagella and penetrates the macro-gamete to form a zygote and ultimately the infectious asexual sporozoites. All in one cell! (Well, one at a time, with lots of mitosis one both sides.)
The ~universally accepted theory underlying the UBD and the evolution of sex ratios
Parker G.A., Baker R.R., Smith V.G.F. (1972). The origin and evolution of gamete dimorphism and the male-female phenomenon. Journal of Theoretical Biology, 36, 529–553. doi:10.1016/0022-5193(72)90007-0
has been cited hundreds of times, including dozens of times in “Evolution” and in “The American Naturalist”.
OTOH the theory underlying genderism is, well, non-existent. There is no quantitative basis for predicting that, as Mark commented earlier today, “Some [who claim gender dysphoria]…really seem to be transgender [and] really are trans and they have to accept it.”
One could argue this is similar to the lack of theory to predict that across cultures and ethnic groups 2–10% of human males and females will report same-sex sexual orientation. But this is changing, for example here
Zietsch, B.P., et al. (2021). Genomic evidence consistent with antagonistic pleiotropy may help explain the evolutionary maintenance of same-sex sexual behaviour in humans. Nature Human Behaviour, 51, 1251 doi:10.1038/s41562-021-01168-8
The jury is still out whether that specific form of natural selection maintains the heritable genetic variation that predisposes some people to same-sex sexual attraction, but the underlying phenomenon is widely accepted because it has an observable biological basis. Genderism not so much.
This is just wildly inconsistent (or if you’re really up in arms about this then hypocritical) for the leadership of three societies whose flagship journals lead the way in the development of quantitative theory to explain evolutionary phenomena, and in which it’s almost impossible to publish new research without at least a nod to the relevant theory, to publish editorial policy statements based on nothing but social and cultural whims. Theory for thee but not for me, it seems.
That is really interesting! The JTB article is the one I use in my evolution class to teach why natural selection would settle upon anisogamy. I teach this with some nervousness, lately, but fortunately I can retire soon.
There is another theory out there called the Hurst-Hamilton hypothesis. I don’t get into that one owing to a lack of time. But here is a very engaging review that covers that and other areas: https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0020183
Ha yes I hope to retire soon as well!
I like the Whitfield paper. Hurst-Hamilton is a good idea but it’s not necessary in order to account for the two sexes in plants & animals (where there are lots of examples of biparental inheritance of organelles).
The harvester ant example seems specious (lit. “beautiful but false”). The ants don’t have 4 sexes, they have 2 sexes each with two different mating types. The different male morphs cause offspring to develop into workers or into queens, but that’s a very highly derived mode of queen determination in ants and bees and wasps; I think but don’t know that the ancestral mode is some kind of hormonal not genetic determination. What do you think?
I think this is the beautiful but false part: “The idea [4 sexes] is particularly potent if one views a social insect colony as a “superorganism” with the workers equivalent to the cells of a body. It’s as if a female mates with one male to produce her offspring’s somatic cells, and another to produce its germ cells.” Whitfield notes that males should want to mate only with females of their own mating type in order to get his own genes into the germ line of the next colony. Leo Buss wrote a great book about how one can think of multicellular organismal embryology as a pile of mechanisms for policing this kind of selfish behaviour of cells and limiting access to the germ line. If harvester ants evolved this complicated system thru the Hurst-Hamilton mechanism, there must be something complex going on that compels males to mate with females of the other mating type as well (and contribute to the “soma” of those other colonies). I don’t think there’s anything in the H-H theory to predict that?
Sorry for the long reply (last comment from me).
VERY LATE reply (Super Bowl party, etc.) I vaguely remember the harvester ant thing and went for another look. Each ant clearly has at most only two parents, but there are two types of males to produce the range of castes in the colony. The authors dabble with the idea that there are three sexes here, but they are referring to the view of someone else at that point.
I think Jerry would enjoy this paper.
I looked up antagonistic pleiotropy and found examples for senescence and for sexual selection, but not for sexual orientation. I’d appreciate a link to something on that aspect, suitable for a non-biologist.
And I’d also appreciate a suitable link with an overview of the current state of “gay gene” issues in general. TIA.
I don’t have a non-specialist discussion of antagonistic pleiotropy in the evolution of sexual orientation. The Zietsch article is the best I can do. The hypothesis is essentially this: many genes each have a small effect on both attractiveness and sexual orientation. If I happen to get few of those genes from each of my parents then I’m likely to be an unattractive guy with low fitness (few offspring); if I get a healthy dose of those genes then I’ll probably be an attractive and sexually successful heterosexual person; if my sibling happens to get a lot more of those genes from our parents than I did then s/he is more likely to become a lesbian or a gay man (also with lower fitness and fewer offspring).
This article from a few months ago seems good as an overview. The authors are concerned about ethical issues in studying sexual orientation and its genetic basis. But they start out by conceding that same-sex sexual attraction is heritable and is associated with lower fitness (fewer offspring), which is the pattern Zietsch is trying to explain.
Ventresca, C. et al. (2024). The methodological and ethical concerns of genetic studies of same-sex sexual behavior. American Journal of Human Genetics, 111, 2107–2116. doi:10.1016/j.ajhg.2024.08.007
Sorry again for overcommenting 🙁
FWIW, methodological and ethical concerns of the research specialists aren’t my concerns. The last I looked (a decade or so ago) there were various competing ideas about the evolutionary basis of same-sex attraction. Some seemed pretty clearly crackpot, and I am wondering whether the dust has settled into more of a consensus. Have there been any relevant whole-genome analyses?
Yes Zietsch is a genome-wide analysis (GWAS).
Cheers to PPC(E) for this excellent riposte to the madness. I hope that as usual large twitter a/c will repost and amplify it.
.
It can be frustrating this kind of stuff – fighting against politically and emotionally driven nonsense. I try to do it with Israel yet we still see pro-Pal terrorists on our streets and campuses. I’m like: Did they not read my articles or something?
I bet PCC(E) is deluded as I am sometimes like that. hehehe
Still the fight(s) are worth it. Truth matters.
Also useful link in there as I’m almost out of sticklebacks. Better grab some!
D.A.
NYC
Having written 3 books on the history of Mendelian genetics, my view might be considered. The issue is not about a strict UBD (“universal biological definition”) of sex, but the definition of sex between members of the human species. Like many characters (e.g., human height) sex is a product of multiple individual genes (multigenic as shown by GWAS).
As a result of meiotic shuffling in parental gonads, different humans inherit different combinations of these genes. Some are, indeed, directly related to the type of gamete that will be produced. However, human sex is, as the Boggs-Bolnick-Ware letter states, “a biological construct that relies on a combination of chromosomes, hormonal balances, and the resulting expression of gonads, external genitalia and secondary sex characteristics.”
Included here, are numerous genes affecting emotions towards one sex rather than the other. Classify them as “primary,” “secondary,” etc., if you will. However, as a result of (relatively rare) chromosomal recombinations, some humans will end up with emotions that differ from those that regularly appear when a certain type of gamete is encoded. Thus, especially in humans, “There is variation in all these biological attributes that make up sex. Accordingly, sex (and gendered expression) is not a binary trait. While some aspects of sex are bimodal, variation along the continuum of male to female is well documented in humans … .”
You are just repeating the Societies’ letter and, in fact, I can’t make heads or tails of what you’re trying to say. What are you talking about when you bring up “emotions”. Finally, we’re talking about biological sex, not gendered expression.
Your first paragraph is completely unintelligible to me. Sex BETWEEN members of the human species??
These tedious boffinosas can keep splitting hairs until their splitters fall off, but they know as well as everyone else that the binary sex categories exist, and that they are sometimes important to the functioning of civilization.
They know this.
I’m also trying to figure this out. My understanding is that, in general, females of the human species tend to be more nurturing and empathetic than males, while males are more aggressive. While social environments are involved, there appears to be a biological or genetic basis for this. And yet variations in development will lead to nurturing males and aggressive females.
Does this now entail that there is a spectrum of male to female, with Mr. Rogers being less male and more female than Hulk Hogan?
If not, could you give some specific examples of what you mean?
I’m also trying to figure this out. My understanding is that, in general, females of the human species tend to be more nurturing and empathetic than males, while males are more aggressive. Social environments are involved, but there also appears to be a biological or genetic basis for this. And yet variations in development will lead to nurturing males and aggressive females.
Does this now entail that there is a spectrum of male to female, with Mr. Rogers being less male and more female than Hulk Hogan?
If not, could you give some specific examples of what you mean?
I’m trained as a physicist, not as a biologist, but I’m afraid with these topics it’s often philosophers who highlight better where things go wrong.
What sex “is a product of” isn’t the same as what sex IS.
Moreover, once you start speaking of variations between members, you are no longer speaking of what sex is, but about how individuals can be labeled, which is a different question (“can every human be classified as either male or female?”).
Finally, even your approach won’t lead where you presume. Do a multi-dimensional plot using as axis your characteristics, you’ll see that the points representing individuals indeed form TWO distinct clouds whose membership we can conveniently call male and female (arguing it doesn’t requires falling for the univariate fallacy).
But that latter question IS the entire question on which the trans ideology hangs. Trans activists aren’t interested in gametes. It’s the labels, the categories of developed bodies that they claim are on a spectrum. It’s all based on the bogus idea that there are no disorders and that all developmental outcomes are equally healthy. Many people arguing against the ideology miss this point.
And yet here you are after all of that, a product of the fusion of a sperm and an egg. Just like 100% of all mammals. What’s that egg and sperm and only an egg and sperm thing called again? But do go on about how everyone’s feelze and attitides make a completely irrelevant continuum spectrum rainbowy sociology 101 something or other.
Imo, motivation:
Certainly not truth and consensus.
3 x presidents lived experience:
head in a ideological hole.
Lie on the sly:
it feels good. Allows one to shoot oneself in the foot.
Bad for science, understanding, reason & rationality.
Limp off into the sunset.
First, there was: Race is a social construct
Now there is: Sex is a biological construct
Next will be:
Homo sapiens are a biological construct and a social construct
The moon is a lunar construct
Electricity is a conductive construct
Plants are a photosynthetic construct
Pain is a nociceptive construct
The ocean is a hydrodynamic construct
Fire is a pyrochemical construct
Walking is a locomotive construct
The alphabet is a phonetic construct
The sun is a heliocentric construct
Music is a vibrational construct
Dreams are a REM cycle construct
Colors are a wavelength construct
Mirrors are a reflection construct
Numbers are a quantitative construct
Breathing is a respiratory construct
The sky is a celestial construct
Cats are a feline construct
Death is a mortality construct
Reality is a perception construct
Next, next will be:
Lunar is a moon construct
Conductive is an electricity construct
Photosynthetic is a plant construct
Nociceptive is a pain construct
Hydrodynamic is an ocean construct
Pyrochemical is a fire construct
Locomotive is a walking construct
Phonetic is an alphabet construct
Heliocentric is a sun construct
Vibrational is a music construct
REM cycle is a dream construct
Wavelength is a color construct
Reflection is a mirror construct
Quantitative is a numbers construct
Respiratory is a breathing construct
Celestial is a sky construct
Feline is a cat construct
Mortality is a death construct
Perception is a reality construct
Thus, of course, logically:
Social and biological is a Homo sapiens construct
Leaving us with:
Race is a social construct
Sex is a biological construct
And so it goes, until language folds in on itself like a Möbius strip of absurdity, leaving us gasping for meaning in a world where even existence is just another construct.
“Mobius strip of absurdity” … I’m stealing that one.
Though trained in science, I am not a scientist, so I cannot possibly know what “sex” is without consulting scientists, much like the lioness in heat who would have no idea with whom she should mate without first consulting a peer-reviewed journal in animal behavior. Given this handicap, I am forced to rely on language to judge credibility. Looking at the letter of the society presidents, my first warning sign was at the beginning: “as scientists.” (Oh, I see, a double play of identity and authority.) Then we have “extensive scientific evidence.” (Um, where?) And the “scientific consensus” clearly contradicts the President. (Oh, goodie, another appeal to authority that one should take on trust. Who but the fool doubts “the consensus”? Not scientists. Never.) Sex is a “biological construct.” (Warning lights flashing. Sociobabble smuggled in, perhaps unaware, signaling the real provinces of “authority” from which this argument arises.) “Lived experience.” (I’m done. Cards are on the table. Might as well declare yourselves cis and state your pronouns.)
“I’ve pointed out before that the sex binary applies to all animals (including of course us) and all vascular plants, but not to protists, algae, and some fungi.” – J. Coyne
If the multiple mating types of these organisms aren’t properly called sexes, then arguing that they constitute a transbinary sex spectrum is based on a conceptual confusion.
“Under the Parker et al. definition of a sex in terms of gamete size, a mating type is not considered to be a sex, but simply a gametic type (that may or may not be related to gamete size) that shows a preference for fusion with certain other gamete types. In isogamous populations, there is thus one sex (though there may be several mating types). Retaining the definition of a sex for an adult phenotype that produces a given gamete size, and a mating type for a gamete phenotype that has a given characteristic for selective fusion may serve to remove some of the confusions that have arisen in the literature.”
(Parker, Geoff A. “The Origin and Maintenance of Two Sexes (Anisogamy), and Their Gamete Sizes by Gamete Competition.” In The Evolution of Anisogamy: A Fundamental Phenomenon Underlying Sexual Selection, edited by Tatsuya Togashi and Paul Alan Cox, 17-74. Cambridge: Cambridge University Press, 2011. p. 17)
“From an evolutionary vantage, the one-and-only phenotypic feature that consistently distinguishes males from females is gamete size. In any multicellular organism, individuals that produce smaller gametes are males, by definition; and individuals that produce the larger gametes are females, by definition. This situation is referred to as anisogamy: the strongly bimodal distribution of gamete size (smaller in males, larger in females) that characterizes the vast majority of sexually reproducing organisms. (In some multicellular algae and fungi, two genetic types of gametes are similar in size, but technically these species do not violate the broader rule because the two genders are referred to as mating types [“+” and “−”] rather than as males and females.)”
(Avise, John C. Hermaphroditism: A Primer on the Biology, Ecology, and Evolution of Dual Sexuality. New York: Columbia University Press, 2011. p. 7)
“[W]hen all else fails, theorists and activists will point to species that do not have male and female sexes. For example, sex spectrum proponents will point to various types of organisms that reproduce through gametes of the same size, a form of sexual reproduction known as isogamy (iso = same, gamy = marriage). Isogamy is most common among simpler organisms like algae or fungi. It occurs when all gametes are morphologically similar, particularly in size, and when the contribution of genetic material and resources to the offspring is shared equally between the two parents. This differs from anisogamy (male-female sex) because, in anisogamy, the two gametes (the sperm and egg) are morphologically different in size and the contribution of resources to the offspring are highly unequal.
Proponents of the sex spectrum claim that isogamous organisms can have tens of thousands of sexes. But this conflates mating types with sexes. Mating types involve isogamy (same size gametes), and sexes involve anisogamy (different size gametes). Mating types are molecular mechanisms that regulate compatibility between fusing gametes. Isogamous organisms like fungi can have thousands of pairs of these complementary gamete genotypes (thousands of unique pairs of locks and keys), and therefore they can have thousands of mating types—but not sexes. Using fungi that do not reproduce through anisogamy as evidence against male and female is an obvious red herring. The only response required to such a tactic is this: humans are not fungi.
Whether it is humans, hyenas, clownfish, seahorses, flowering plants, slugs, or other kinds of anisogamous species, the sexes are defined the same: two roles organized around the production of two gametes of differing size and form. As evolutionary biologists Jussi Lehtonen and Geoff Parker write [“Gamete competition, gamete limitation, and the evolution of two sexes,” 2014]:
—
Of course, in many species a whole suite of secondary sexual traits exists, but the fundamental definition [of sex] is rooted in this difference in gametes, and the question of the origin of the two sexes is then equal to the question of why do gametes come in two different sizes.”
(Elliott, Zachary A. Binary: Debunking the Sex Spectrum Myth. Paradox Press, 2023. pp. 17-8)
This raises what seems a relevant question: What is it about the currently isogamous that resisted the selective pressures that made the whole rest of the biological world anisogamous? IANABiologist.
I think it’s primarily
unicellular species or only recently multicellular species — anisogamy seems to evolve very soon after multicellularity
if little dispersal is needed/possible — perhaps many fungi, where its underground hyphae meeting up, and dispersal is through spores. A little googling suggests it would take a lot of work to get around all the various things fungi do however!
Oh I’m not going to dis any fungi — I’ve watched The Last of Us 🙂.
A lot of learned, expert comments above, which are much appreciated. All I can add is congratulations to our host on his 30,000th post, and many thanks for the endless education, edification and entertainment I have been privileged to enjoy over the years.
As regards this latest example of ‘trahison des clercs’, it seems clear that the tide is turning. I would like to think that, not long in the future, this shameful (and shameless) statement will be widely regarded with the ridicule and contempt it deserves.
Here’s to the next 30,000!
Absolutely shameful. I fail to see how Carol Boggs, Daniel Bolnick, and Jessica Ware can credibly be leaders of these organizations while unable to define biological SEX (not even gender)! Disqualifying. It would be like the president of the Genetics Society claiming that double-stranded DNA is not the basis for heredity and that there is a spectrum of helices involved.
I’m so sick of the argument that sex in protists can be extrapolated to mammals which is illegitimate and they know it. The question they must answer is: name me a mammal (of which humans are a member) that is isogamous. Answer: ZERO! Further, do humans exchange genetic material using plasmids? Answer: NO!
OK, having established that and to Jerry’s point, how can you tell the sex of a human individual?
Genetic and morphological abnormalities (i.e. intersex or non-binary) are not violations of the male and female sex categories but exceptions that violate the definition of terms akin to amputees being evidence that humans are not bipedal. No.
I’ll go further. Anonymously poll the members of these professional societies on whether they agree with the definition of sex espoused by their society presidents and let that be a referendum on the legitimacy of them holding that office. They would be dismissed and frankly, should be.
Congrats on 30,000 posts! I have been writing for almost ten years on three different platforms and haven’t published a tenth as many.
I admire, and have written in my blogs, the fact that you are not blinded by any ideology except for a desire to seek the truth. We are (probably) on opposite sides of the political spectrum (I don’t believe in government as panacea and think that smaller government is always better, ceterus paribus), but I agree with much that you write.
Thank you for this website!
Golly, just getting to email at the end of the day and post 30,000, well, it sure does meet expectations. Likewise most of the comments above. Heartfelt agreement and heartsick it’s come down to post-modern trends…oh, see how deep the rot goes. I wish they hadn’t gone & done those muddled pandering statements. See here now, as I scientist I must say — oh, never mind. No wonder vaccination rates are plummeting.
Thanks for the 30,000 posts. I read WEIT as close or everyday as I can and am always glad for a new post. This reminded me to pull WEIT from my bookshelves. It is time to read it again.
I can’t imagine being able to produce as much good work as you have accomplished.
“… variation along the continuum of male to female is well documented…”
In which they acknowledge the binary nature of sex. Oof.
Commenter #3, from Europe, wonders at the capture of professional organizations by nonsensical fads in the US, in this case gender ideology. I think fads of this kind are often more intense in the US than than in Europe. Previous US examples include the recovered memory therapy fad; the “whole language” fad for teaching reading (did anything comparable even exist in Europe?); and, of course, the entire media industry concerning UFOs, alien abductions, sasquatches, angels, and so on (see “Coast to Coast” radio). The latter example suggests an explanation for the more intense US spread of certain varieties of bullshit: communication media dominated by the advertising industry. Maybe the US differs from Europe in the extent to which the entire culture is influenced by advertising—in the way that Europe’s culture was once (but no longer) influenced by the church.
I’m going to recommend a book on this very topic: Fantasyland: How American Went Haywire by Kurt Andersen. He traces the US tendency towards fads and conspiracies right back to the first folks who came over from Europe: religious fanatics and people wanting to get rich.
I think you’ll find it interesting.
Thanks, Sastra, I might look for that book. On the other hand, and contra the
subject under discussion, some US fetishes do travel across the Atlantic at least
as far as old blighty. See: https://unherd.com/newsroom/british-universities-are-doubling-down-on-dei/?tl_inbound=1&tl_groups%5B0%5D=18743&tl_period_type=3&utm_source=UnHerd+Today&utm_campaign=1567774e7a-EMAIL_CAMPAIGN_2025_02_10_09_57&utm_medium=email&utm_term=0_79fd0df946-1567774e7a-36034798
I am a post doc studying sexual selection, and a past member of both ASN and SSE, and I was infuriated with the letter written by these presidents. They completely deny one of the most important theories set out by great theoreticians like Geoff Parker, about the evolution of anisogamy and how this leads to sexes. As many others have said in the comments, sex is real, and binary. Yes, there are species where individuals can be simultaneously hermaphroditic, but that only means that they have both male and female gamete producing capabilities, and it does not eliminate the existence of Male and female. And the secondary sexual traits that the presidents list out in their letter ARE NOT THE BIOLOGICAL DEFINITION OF SEX USED BY ANYONE. It’s evolution class 101 where sex is defined as the relative number and size of your gametes!! Nothing more. Every other trait like chromosome, hormone, breasts, etc are secondary sexual traits which either just correlate with gamete type or are a consequence of a specific gamete producing strategy.
What annoys me the most is the presidents claiming to speak on behalf of all evolutionary biologist/members without their consent or knowledge!
I hope biologists who oppose this letter make their voices heard to the US public, so that scientists and general public do not think that these learned societies have lost their mind and scientific rigour to ideology.
Great post Jerry. Congrats on the 30,000 landmark!
What worries me about the SSE, ASN & SSB is that these scientific bodies have been captured by anti-science ideology to the point they are publishing anti-science rhetoric aimed at the President, no less. This is damaging to science in the round.
We are at a time when we need science more than ever. And that science needs to be understood and believed by the public and government, so that decisions around health, the environment and the climate are made correctly.
This letter from SSE will allow anti-science people to declare that either science backs their non-scientific views or that science is malleable to non-scientific influences and can be ignored. The result is that the public and decision makers will no longer take scientists seriously. They won’t value a true scientist’s input on their expert opinion any more than that of an ideologue who is abusing science or a huckster using the situation to make money.
And don’t get excited about Trump seeing scientific light. He is using a scientific definition of sex to bolster his beliefs about transgenderism. He will just as happily depart from science where it doesn’t suit him (see his views on climate and the appointment of RFK jr) and people like those responsible for this terrible letter are feeding him ammunition to do so.
Where are the publicly known scientists talking about it? Neil deGrasse Tyson has fallen down the gender hole, only Dawkins is speaking up. We need Richard Feynman and Carl Sagan more than ever, their premature passings were tragedies for humanity.
That such august scientific bodies are participating, even leading, such a blatant attack on science is a tragedy. We will all be poorer for it. Many people will die because of it.