Debunking Pseudoscience: ‘Multimodal Models of Animal Sex’

A new paper proposes a “multimodal” model of biological sex. Here’s why it’s pseudoscience.

Reality’s Last Stand is a reader-supported publication. Please consider becoming a paying subscriber or making a one-time or recurring donation to show your support.

In recent years there has been a concerted effort by activists to debunk the longstanding scientific consensus that the categories male and female represent real and discrete biological categories in humans. The Oxford philosopher Amia Srinivasan, for instance, rejects the notion that biological sex is “natural,” “pre-political,” or “objective,” claiming instead that it is “a cultural thing posing as a natural one.” UC Riverside’s Gender and Sexualities Chair, Brandon Andrew Robinson, claims that we “should stop teaching that sex is biological” because we “assign meaning to certain things…because of dominant gender ideologies.” In this view, categorizing people as male or female is not only biologically incorrect but also harmful and oppressive.

For a long time these ideas festered away in humanities departments without serious inroads with the hard sciences. But as Queer Theory and social constructivism became entangled with notions of “Social Justice” and Left-wing politics, and as political discourse has become increasingly polarized, many activist scientists have been attempting to provide an imprimatur of legitimacy to these anti-scientific beliefs.

Early attempts at debunking the two-sex model sought to expand the number of sexes beyond two. One such example is Brown University Professor Emerita Anne Fausto-Sterling, who claimed the “two-party sexual system” in humans was “in defiance of nature,” and that there were instead “at least five sex categories, and perhaps even more.” However, the additional sexes she proposed simply corresponded to various intersex conditions, not new sexes akin to the functional reproductive roles that universally define all males and females.

More modern attempts to debunk the binary nature of sex have moved away from trying to discover new sexes, and have instead called for the elimination of sex categories entirely in favor of viewing sex as a continuous, although perhaps bimodal, spectrum consisting of many traits. Such ideas have found homes in the pages of Nature and popular science magazines like Scientific American. Figures like the one below are often used to visualize this model.

This representation of sex has proven popular because it accords with our intuitive (albeit naïve) sense that most of us cluster around a typical male or female typology while recognizing that our various anatomical traits are quite variable. I’ve written a lengthy rebuttal of the sex spectrum model here, but the short version of it is that the sex spectrum model conflates traits that are influenced by one’s sex—such as breast size, body hair, voice pitch, hip morphology, etc.—with sex itself, which is defined by one’s primary sex organs (i.e., testes versus ovaries).

Because the sex binary has been deemed “oppressive” and invalidating of transgender identities and experiences—cardinal sins of our age—this has started an arms race among activist scientists to come up with a model of sex that is the least binary thing imaginable. Since the “bimodal spectrum” concept still entails two of something, this must be abandoned as it may be seen as problematically implying a fundamentally binary underlying property that’s producing the bimodal distribution of sex-related traits—and they’d be right!

In pursuit of this goal, a “Multimodal Sex literature survey team” composed of researchers from UC Berkeley and Loyola University Chicago has been assembled to “re-imagine a more inclusive framework for biological sex.” On January 27, 2023, the team produced their first pre-print titled “Multimodal models of animal sex: breaking binaries leads to a better understanding of ecology and evolution.” The paper argues that sex is best viewed as “a constructed category operating at multiple biological levels” (C) rather than binary (A) or bimodal (B).

This figure has been reproduced from the original manuscript for better resolution.

To support their assertion, the authors first survey sex at four different “levels”—genetic, endocrine, morphological, and social—in order to interrogate the degree to which these traits can be considered binary. Next, they present three “case studies” where they claim sex “may be better categorized as multimodal” as opposed to “binary or bimodal.” The authors conclude that their “expanded understanding of ‘sex’ better equips us to understand evolutionary processes on their own terms,” and will help biologists “push back against misunderstandings of the biology of sexual phenotypes that enact harm on marginalized communities.”

The arguments presented throughout the paper are not just poor, but are rooted in a fundamental misunderstanding of the universal defining property of all males and all females across all taxa—having the function of producing sperm or ova, respectively. That any individual scientist, lab, or “survey team” could claim to be expanding the boundary of our knowledge on a topic that they do not understand at its core is embarrassing.

In saner times such a paper would perhaps elicit a small chuckle from a journal editor before issuing a swift rejection. But current times are far from sane, and the quick ascendance of fashionable pseudoscience in academia on the biology of sex gives us ample reason to worry this paper will not receive the withering review it deserves.

So allow me to provide that now.

---

Lengthy and thorough rebuttals like the one below take considerable time and effort to produce, but are necessary. If you find my work valuable, please consider becoming a paying subscriber or making a one-time or recurring donation.

Sincerely,

CW

---

Knocking Down Strawmen

A common tactic activists scientists use to bolster their new models of biological sex is to construct a scientific opponent who simply does not exist. When attempting to debunk the binary nature of sex, this is typically done by misconstruing and over-applying the fundamental binarity of sex relating to gametes (i.e., sperm versus ova) to sex differences generally. For instance, they might point out that while there are only two types of gametes (sperm and ova), height differences between males and females are nevertheless not binary. Thus, what they often portray as being exceptions to the rule of binary sex categories are actually just gross conflations of two very distinct concepts—sex itself (i.e., the state of being male, female, or both) versus any and all measurable sex-related differences. But not all sex differences are differences of sex.

To my knowledge, no biologist has ever claimed that males and females differ discretely and absolutely in every conceivable way. And if a biologist were to claim such a thing, they would be immediately laughed out of the room as it is so obviously untrue.

This is the strawman the authors begin constructing in their introduction when they claim that “the common assumption is that there are two sexes, strictly classified as female or male” that’s rooted in gamete size.

In sexually reproducing species, the common assumption is that there are two sexes, strictly classified as female or male (Fisher 1930; Hurst 1996; Jaffe 1996). This assertion is supported by the cellular mechanisms of sexual reproduction, in which multiple (usually two) parental gametes combine genotypes to create an offspring with a novel genetic makeup. In animals, these gametes are of different sizes (e.g., large ova and small sperm), a condition called anisogamy.

The authors then go on to present supposed challenges to the “common assumption” of two sexes. The first challenge they posit is the existence of hermaphroditic species, which they believe violates the binary sex model because individuals produce both sperm and ova and “do not have separate sexes.”

However, the binary classification of gametic sex breaks down when we consider the broader diversity of gametic phenotypes. For instance, hermaphroditic species possess both gamete types required for reproduction, and do not have separate sexes (Jarne and Auld 2006).

The sex binary, however, does not require that the two sexes exist in separate bodies. The authors are simply conflating the sex binary with a phenomenon called gonochorism or dioecy, which is “the condition of individual organisms within a species existing as one of two possible sexes, specifically male or female.” The existence of hermaphroditic and gonochoric species just represent different ways a species can utilize male and female reproductive strategies. Regardless of whether an organism is only male, only female, or both male and female, there are still only two fundamental functions—the production of sperm and/or ova.

Two sexes, housed differently.

The second challenge to the sex binary raised by the authors involves the existence of isogamy, which is a type of sexual reproduction in some species that involves combining gametes of equal size.

Outside of animals, systems of sex determination rely on genetic markers that determine compatibility between equally-sized gametes, a condition known as isogamy (Togashi and Cox 2011) found in fungi (Kothe 1996; Lee et al. 2010; Billiard et al. 2011, 2012), algae (Perrin 2012; Tillmann and Hoppenrath 2013), and amoebozoa (Douglas et al. 2016).

The issue here is that the sex binary does not apply to isogamous species, because they do not, by definition, have sexes; instead, they have mating types. But no biologist has ever claimed isogamous species are comprised of two sexes, because that would be literally meaningless in this context. The authors appear to be conflating sex (as in sexual reproduction) with sexes (males and females). But there can be sex without sexes. So, once again, the authors are relying on demolishing nonsensical strawmen to make their case.

To make their strawman argument even more explicit, the authors quote the biologist Joan Roughgarden saying that “the biggest error in biology today is uncritically assuming that the gamete size binary implies a corresponding binary in body type, behavior, and life history.”

Now let me make my point more explicit: biologists do not claim that “the gamete size binary implies a corresponding binary in body type, behavior, and life history,” because such a claim is absurd, unnecessary, and easily refuted by the most cursory glance at reality.

The final strawman the authors construct is to incorrectly assert that “sex” is a term “used to encompass a broad collection of gametic, genetic, hormonal, anatomic, and behavioral traits.” They claim that semantically flattening all of these traits into “a binary model, for which individuals are classified as either ‘female’ or ‘male’” is “an oversimplification, since ‘sex’ comprises multiple traits, with variable distributions.”

While this portrayal of sex as a combination of many traits is a common belief among those who lack a fundamental understanding of what it means to be male or female, this does not track reality. Rather, these traits are upstream mechanisms that guide sex development and downstream consequences of one’s sex. They do not describe sex itself which, again, refers only to the function of producing a certain type of gamete.

The authors assert that a binary understanding of sex “fails to accurately capture the diverse and nuanced nature of sex,” but in reality the underlying binarity of sex serves as a central organizing principle that affords us a much deeper understanding into patterns of evolved sex differences in nature than would be possible by looking at every trait in isolation. Nobody is insisting that every axis on which males and females differ on average must be collapsed into a binary. Two things can be true at once: sex is fundamentally binary, yet this binary can be expressed in myriad ways both anatomically and behaviorally. There is no contradiction here.

The paper’s next four sections interrogate the degree to which sex is binary at four different “levels”—genetic, endocrine, morphological, and social. I will cover each of these sections briefly to highlight their fatal flaws.

‘Sex at the Genetic Level’

This section covers various genetic “sex determining” mechanisms in nature. For instance, they describe chromosomal sex determination systems in mammals where males generally have XY (heterogametic) sex chromosomes and females have XX (homogametic) sex chromosomes. This is contrasted with birds where the males have ZZ (homogametic) and the females have ZW (heterogametic) sex chromosomes. They highlight systems where sex development is triggered not by the presence or absence of certain genes on sex chromosomes, but rather by their dose. Other systems use a combination of gene presence/absence and dose dependence.

Some species, like many reptiles, don’t use sex chromosomes at all to trigger sex development, but rather the temperature at which an embryo is incubated will turn on or off genes that cause it to develop into a male or female. And in some cases genetic pathways and environmental factors can interact to guide sex development.

There are indeed many complex and interesting ways that sex can be determined in nature, but the authors’ take-away from all of this complexity is to conclude that, “Altogether, evidence from these diverse species reveals that genetic sex is not the universal binary often assumed, and that genetic sex is one variable among the many traits that comprise multimodal sex.”

This conclusion is nonsensical because it muddles cause and effect by conflating how sex is determined with how sex is defined for an individual. “Sex determination” is a technical term in developmental biology referring to the process by which certain genes trigger and regulate sex development in an embryo. As covered above, these mechanisms can be genetic, environmental, or a complex mixture of both. However, no matter how sex is developmentally determined for an individual, their sex is always defined the same way—by the type of gamete they do or would produce.

This should be obvious, as it would have been literally impossible to have ever discovered these different sex determining mechanisms without first knowing what males and females are apart from the genes and environmental factors that produce them. The only way we know, for instance, that male birds typically have ZZ chromosomes, that male mammals are typically XY, and that male alligators typically develop at incubation temperatures over 34°C, is because being male (or female) is independent of the mechanisms that produce them.

Nobody ever claimed that the existence of two sexes required sex determining mechanisms to be simple and binary. That is a made-up claim.

The last part of this section gets even more bizarre, as they attempt to include the various reproductive strategies, or ways that “genetic material is transmitted to the next generation,” as evidence against the sex binary. They believe that because some organisms reproduce sexually, some asexually, and some utilize a combination of sexual and asexual reproduction, this somehow presents a challenge to the idea that there are only two sexes. But how organisms utilize sex is entirely irrelevant to the question of how many sexes there are.

The authors conclude that “The vast array of sexual determination and reproductive systems challenge frameworks that impose human cultural binary categories on animals, and show how even at the most fundamental levels, the biological underpinnings of sexual phenotypes are extremely diverse and multimodal.” Yet, in reality, everything they have presented is demonstrative of the binary nature of sex, and their language so far has yet to reference a third sex beyond male and female.

‘Sex at the Endocrine Level’

In this section, the authors attempt to dispel what they claim is a “common misconception” that “androgens regulate ‘masculine’ phenotypes and estrogens regulate ‘feminine’ phenotypes.” They say that this has led to the use of terms like “masculinization” and “feminization,” which they say is “circular and confusing” because “both females and males possess the capacity to produce, metabolize, and respond to these hormones.” Further, while they acknowledge that “testosterone levels in circulation are typically higher in males than in females, for many species, there is no testosterone threshold for ‘maleness.’” Because of the “daily, seasonal, and cross-species variation in hormone levels” observed in many species, the authors conclude that “hormone levels are not a binary indicator of sex.”

This is a common argument levied by gender activists attempting to dismiss the differences between males and females as simply being a matter of degree. While it is true that hormones are involved in and guide the development of many sex-related differences in anatomy and overall phenotype, hormone levels do not define an individual’s sex. We label androgens like testosterone “male” or “masculinizing” because of their central role in guiding the development of male secondary sex characteristics. Likewise, estrogens are labeled “female” or “feminizing” because of their central role in producing adult female phenotypes. These labels are given to these hormone classes in retrospect because of their observed effects in guiding sex development for males and females.

Nobody ever claimed that hormone levels are “a binary indicator of sex.” This is simply another strawman they’ve constructed. Hormone levels are correlated with an individual’s biological sex, but they don’t define one’s sex. This should be obvious, because it would be impossible to say that androgens are correlated with being male, and estrogens female, unless we were already aware that being male and female is something separate from hormone levels.

‘Sex at the Morphological Level’

In this section, the authors attempt to debunk the sex binary by showing that “the presence, shape, and size of genitalia, such as the vaginal opening or phallus, do not always fall into neat categories of sex.” They take issue with organismal biologists who “often make binary sex assignments to individuals based on their primary sexual characteristics, despite the diversity of genital morphology within and among taxa.” To make their argument, the authors give several examples: female hyenas with pseudo-penises; Neotrogla barkflies where the females have a penis and the males a vagina; male lizards with different hemipene morphology based on their mating strategy; the absence of phalluses entirely in 97 percent of bird species; male pregnancy in seahorses and pipefish; and other various examples of genital diversity in nature.

But primary sex characteristics (penis, scrotum, vulva, vagina, etc.) do not define an organism’s sex. In some species these organs have evolved to help facilitate reproduction, and can therefore be used as a highly reliable (although not totally infallible) proxy for identifying who the males and females are at a glance, but these organs to not ultimately define males and females.

These “binary assignments to individuals based on their primary sexual characteristics” are done after we have identified who the males and females are in a species by observing who produces sperm or ova, respectively. We know female hyenas have a pseudo-penis because they produce eggs. We know female Neotrogla barkflies have a penis (or gynosome) and males have a vagina because we know which gametes they produce. We know that male seahorses and pipefish become pregnant because we know they produce sperm. We know that different male lizard morphs are all male because they all produce sperm. We know the sex of birds in species with or without phalluses because we know the type of gametes they produce.

See a pattern?

The authors then go on to argue that variation in secondary sexual characteristics, which include trait differences between males and females that are not directly involved in reproduction like ornamentation, weaponry, and other anatomical traits, also disprove the sex binary.

One example they provide is the existence of “three morphs of male ruffs” that “exhibit extremely divergent size and plumage ornamentation, which correspond to alternative mating strategies and chromosomal genotypes.” Another example is a species of damselfly that exhibits “three female morphs, consisting of two ‘gynomorphs’ that vary in color, and one ‘andromorph’ that closely resembles males in color, sexual ornamentation, and behavior.”

The authors conclude that because “there are many cases in which the distribution of these [primary and secondary sexual morphologies] is multimodal,” this disproves the existence of only two sexes.

But how was it ever determined that there are “three morphs of male ruffs” or “three female morphs” in a species of damselfly where two resemble females and one males? What does it mean to resemble a male or female here, as opposed to being a male or female? The existence of multiple morphs of a sex, even when one acts as a mimic of the other sex, does not disprove the existence of two sexes. Morphs represent variation within a sex, and sex mimics are mimics—one sex imitating the other sex.

Every example the authors give as evidence against the sex binary actually confirms it. The sex binary is based solely on the binary distinction between sperm and ova, a distinction the authors of this paper fully understand (whether or not they’d ever admit it) because of how they use the words male and female throughout the paper as something totally distinct from genes, hormones, and genitalia.

‘Sex at the Social Level’

This section is perhaps the most bizarre, as it attempts to debunk the sex binary by arguing against “scientific notions of how animals ‘should’ behave” or “sex role theories,” which they claim “originate with Darwin in the Victorian era.” Specifically, they take aim at what they call the “Darwin-Bateman paradigm,” also known as Bateman’s Principle, which they claim “posits that anisogamy drives the direction of sexual selection to be stronger in males, resulting in ‘traditional’ sex roles for male-male mate competition and female mate choice.” The authors claim that because “many examples in fish, frogs, and birds” appear to “contradict the notion that the sex with the larger gamete suffers higher mating costs and invests more resources into the next generation,” Bateman’s Principle is wrong.

There is a lot wrong with this line of argument. The first is that Bateman’s Principle was never meant as a defense of “traditional sex roles” or suggest “how animals should behave.” Bateman was simply trying to find an explanation behind the well-documented pattern in nature that males tend to exhibit more intra-sexual competition for mates than females. In his 1948 paper in Heredity, Bateman never claimed this was the case for every species, and was careful in his language to avoid making universal claims.

Bateman performed an experiment in Drosophila fruit flies to test the hypothesis that differences in observed mating behavior and intra-sexual competition between males and females was driven by the different investment costs associated with producing sperm versus ova. While he concluded that this was the case in Drosophila, he never claimed this was the case for all species. In other words, Bateman was claiming to have discovered a mechanism for a widely observed trend in nature, not a universal rule that applied in every case.

While the authors claim that exceptions to Bateman’s Principle in “fish, frogs, and birds” contradicted the rule, Bateman himself raised some of these exceptions in his original paper, such as in fishes.

The second issue with the authors’ claims is that it has absolutely nothing to do with how many sexes there are. Mating systems are extremely diverse, but the relative levels of intra-sexual competition and promiscuity of males and females in any species have no bearing on the sex binary.

The authors conclude that “Compared to the other traits we review, sex studied at the social level seems to more readily acknowledge variation outside of binary categories, perhaps because plasticity is a fundamental aspect of behavioral research.” This muddled conclusion is a result of conflating any and all sex-related behavior with the fundamental property of being male or female, but these are completely different concepts.

Three Case Studies

1. Sex-Role Reversal

In this section, the authors present three different "case studies” that are meant to demonstrate how the multiple “independent levels of sex” surveyed in the previous sections can be integrated “in a multimodal framework.”

The first case study looks at several “sex role reversed” species that “defy ‘traditional’ expectations of social sex roles” like “male competition and female parental care.” They focus on four different bird species that fit this description and thus “present fascinating cases of multimodal sex.”

The authors touch on each “level” of sex mentioned above for these species, and claim this demonstrates why “binary thinking” is limiting. For instance, at the social level it is the females who compete for multiple mates, while the males care for young. At the genetic level, females are the heterogametic sex. At the endocrine level, “sexually selected traits like weaponry, plumage ornamentation, and aggression” are controlled by hormone levels in females but not males. Morphologically, the females are larger than males. All of this, according to the authors, demonstrate that “‘sex-role reversed’ systems clearly defy a binary framework.” But does it?

Not even a little, because the “sex binary” does not refer to, and was never meant to be applied to, every measurable genetic, hormonal, morphological, or behavioral difference between males and females. And it is absurd to suggest it ever was or should be.

The authors say that these systems should not be considered “rare exceptions,” but should be used as “a model to understand the multimodality of sexual phenotypes.” But “sexual phenotypes” are not the same as sex itself, and untethering these species from a binary male-and-female framework actually obscures what makes these systems interesting. Indeed, the only reason the authors selected these species in the first place is because they provide an interesting contrast to a more general pattern. But understanding the conditions that bring about interesting exceptions to a rule give us a deeper understanding of both the rule and the exceptions. If we totally ignore the general pattern as a backdrop and simply view species in total isolation, we will have turned science into mere stamp collecting and sacrificed true understanding.

2. More Than Two Sexes?

The second case study claims to investigate “the evolutionary consequences of more than two sexes.” Perhaps here we will finally be told what these new sexes are! But the first sentence moves the goalpost from “sexes” to “operative sexes,” which they never define.

The example they give of a species “with more than two sexes” is the white-throated sparrow (Zonotrichia albicollis). This species has two color morphs, males and females with either white or tan stripes. The more aggressive white stripe morph has a large inversion on chromosome 2, and the species mates disassortatively by color morph, meaning that white stripe morphs tend to mate with tan striped morphs. This chromosome inversion coupled with the disassortative mating by morph has led to a situation where chromosome 2 “behaves like” another sex chromosome.

But having more than two sex chromosomes is not the same as having more than two sexes. While this species may be an interesting case study for how sex chromosomes have evolved, it certainly isn’t an example of a species with “four sexes,” which would require four distinct gamete types.

The authors also bring up a species of Pogonomyrmex ants that they claim “requires three sexes to operate, and four to persist beyond.” Having studied ants in graduate school I thought I would have heard of an ant species with three or four sexes. However, after looking at the paper cited, it’s clear that the paper’s author, Joel D. Parker, is just as confused about what constitutes a new sex as the authors of the multimodal sex paper.

Here’s how the ant paper’s introduction begins:

Fisher’s observation that ‘the sexes are, in fact always two’ might have been premature. Two recently discovered systems within the ant genus Pogonomyrmex (one in P. rugosus, the other in P. barbatus) each comprise two distinct types of female and two distinct types of male.

But “two distinct types of female and two distinct types of male” does not equal four sexes; it equals two sexes. The “distinct types” of females and males are not their own unique sexes—they’re just different types of males and females. At most this system could be described as two sexes and four mating types.

The authors finish this section with a rare instance of self reflection, admitting that “It is typical to frame such systems as having subtypes of two sexes.” However, they say that “if we are willing to consider the white- throated sparrows and Pogonomyrmex systems as having more than two sexes, why not apply a similar framework to the ruff and other polymorphic systems?”

Yes, if you are willing to abandon the universal definition of male and female and expand it to include “mating types,” then sex is no longer binary. Doing so would require us to ignore anisogamy as a distinct type of reproductive system, or simply come up with a new words to describe “males” and “females.” But our current terminology works perfectly well, and we must not give in to making our scientific language less precise to satisfy political sensitivities.

3. Ecological Consequences of Multimodal Sex

This case study is somehow the most confused and irrelevant in debunking the sex binary. It begins by correctly pointing out that “Not all members of the same sex look and behave the same way,” but goes on to describe these same-sex color and behavioral morphs as being different sexes. They even refer to these different morphs as examples of “intrasexual polymorphism,” which means morphs within the same sex, yet they conclude by asserting that “Collapsing intrasexual polymorphisms into a female-male binary erases extensive multivariate phenotypic variation.”

This just makes no sense whatsoever. They admit that these color and behavioral morphs represent variation within males and females, yet somehow believe that describing the system in terms of males and females “erases extensive multivariate phenotypic variation.” Yet this is not the case, because the “extensive multivariate phenotypic variation” is fully retained in describing the variation as “intrasexual polymorphisms.” Abandoning the binary sex framework at its root erases a much more fundamental framework.

Conclusion

The paper ends with a discussion about “the interplay of science and society” that reveal the authors’ true motivations. They assert that “uncritically applying a simple binary without considering the mechanisms shaping sex-specific effects can confound inferences and completely erases the biological realities of TGNC and intersex people.” Further, the authors state:

The historical legacies of sexism, racism, queerphobia, and ableism have deeply influenced the frameworks we use to study nature. Challenging these foundations is difficult but vital to both increasing inclusion in biology and dismantling assumptions that interfere with our ability to observe the natural world on its own terms.

It is undoubtedly true that sexism and racism has historically interfered with producing good science, but we cannot allow new passions and political ideologies to do the same.

The authors make their political motivations explicit:

There is pressure for scientists to avoid making the politics of our work explicit, especially those of us who do not directly study social issues. However, especially in the United States, legislation targeting TGNC people is increasingly undergirded with simplistic binary language purportedly rooted in biology.

Because they believe “binary language” is fueling “legislation targeting [transgender and gender nonconforming] people,” all binary language must be abandoned. As scientists, the authors say we are “best situated to communicate how nature is a rich tapestry of diversity that affirms, rather than invalidates, human experience.”

As biologists we should not be engaged in erasing, invalidating, or affirming people’s identities or experiences. Our job is simple: describe and explain the natural world as accurately as possible.

This paper may be an attempt to incorporate diversity, equity, and inclusion (DEI) into their research program. Many scientists are now required to state explicitly when applying to faculty positions how their research relates to DEI. It should come as no surprise that forcing scientists to inject political initiatives into their research to remain eligible and competitive for grants and promotions comes at the cost of scientific rigor.

In the end, the authors have failed to demonstrate anything other than the existence of two sexes. In fact, their language throughout reveals the fundamentally binary nature at the root of every phenomena they claim debunks it. They have done nothing but demonstrate their complete ignorance of a field they are claiming to be advancing, and have made their political motivations for doing so explicit.

Because this paper is currently a pre-print, that means it has not yet completed peer review. It may be under review somewhere right now. Let me be clear: this paper does not deserve a review; it deserves an immediate rejection without comment. However, given current political trends, I do not trust the review process to filter out papers of such poor quality drenched fashionable DEI rhetoric.

I hope that my review can shine a light on this paper before it is published, and make any editors or reviewers think twice before allowing it to taint their journal’s pages. Good academic reputations are built over decades and even centuries, but they can be destroyed in an instant.

---

Organizations to Support

• Society for Evidence-Based Gender Medicine (SEGM)

• Sex Matters

• Parents Defending Education

• Transgender Trend

• Genspect

• Foundation for Individual Rights and Expression (FIRE)

• Women’s Liberation Front (WoLF)

• Women’s Declaration International

• LGB Alliance

• Fair Play for Women

• Counterweight

• The Free Speech Union

• Heterodox Academy