Misleading letter from three scientific societies, arguing that sex is a spectrum in all species, remains online

As I wrote on February 13:

. . . . the Presidents of three organismal-biology societies, the Society for the Study of Evolution (SSE), the American Society of Naturalists (ASN) and the Society of Systematic Biologists (SSB) sent a declaration addressed to President Trump and all the members of Congress. (declaration archived here)  Implicitly claiming that its sentiments were endorsed by the 3500 members of the societies, the declaration also claimed that there is a scientific consensus on the definition of sex, and that is that sex is NOT binary but rather some unspecified but multivariate combination of different traits, a definition that makes sex a continuum or spectrum—and in all species!

You can see the tri-Societies’ announcement, published on February 5 on the SSE’s website, by clicking on the headline below:

On Feb. 13,, 23 biologists wrote to the Presidents of the three societies (our letter is at the link above), correcting their view that sex is a “construct” and is multidimensional. (Our response was largely confected by Luana Maroja of Williams College.) We emphasized that biological sex in humans (and in other animals and vascular plants) is as close to a binary as you can get (exceptions in humans range from 0.005% to .018%). We noted as well that biological sex is defined by the nature of the two observed reproductive systems in nature: one designed to produce large, immobile gametes (females) or small, mobile gametes (males). In some species of plants there are individuals of both sexes (“hermaphrodites”), but there are only two separate sexes, and each species has only two types of gametes.

We later got more people to sign the letter to the societies, ending up with 125 signatures of people willing to reveal their names.

The Presidents of the three Societies did not answer us at first, though eventually they did respond, though we cannot publicize their private email.  I’ve outlined the tenor of their response here, saying that they largely conceded our points:

 I will say that [the Society Presidents] admitted that they think they’re in close agreement with us (I am not so sure!), that their letter wasn’t properly phrased, that some of our differences come from different semantic interpretations of words like “binary” and “continuum”(nope), and that they didn’t send the letter anyway because a federal judge changed the Executive Order on sex (this didn’t affect our criticisms). At any rate, the tri-Societies letter is on hold because the organizations are now concerned with more serious threats from the Trump Administration, like science funding.

So the letter was never sent, and is still sitting on the SSE website, an embarrassing and biologically misleading example of virtue signaling. Nor did they answer Luana Maroja’s subsequent email asking whether they would remove the announcement from the SSE website and inform the Societies’ members of the change.  They have been notably unresponsive, and, although admitting problems with their announcement about sex, they have neither changed the letter nor explained how it is misleading.

You can see all my posts about this kerfuffle here. Besides our weighing in, Richard Dawkins put up two relevant posts on his website, one mentioning the kerfuffle and explaining very clearly why there are only two sexes, and the other showing that even the three Presidents who wrote the declarations implicitly accepted the binary nature of sex in their own published research.

Given that the three Society Presidents who wrote the letter never sent it, and have backed off on its assertions, I call on them to either retract the letter or clarify and qualify it. Right now it stands as an embarrassment to not just the Societies, but to biologists in general—people who are supposed to be wedded to the truth and not to woke ideology. It goes without saying that the claim that sex is nonbinary is made simply to make people who feel that they’re neither male nor female feel better about themselves. But someone’s self-image should not depend on biological definitions and realities. It does not “erase” non-binary people, nor diminish their worth, to note that biological sex is binary.

I will echo Ronald Reagan, “Please, Society Presidents, tear down that announcement.”

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Finally, in a new post called “Debunking Mainstream Media Lies about Biological Sex,” Colin Wright shows that this kind of distortion is widespread in the media. Here’s how he begins his defense of the sex binary—by showing  misleading articles in the media (he mentions the SSE statement):

On January 20, 2025, President Trump signed an executive order affirming the binary nature of sex in federal law, a move that was solidified a month later by the Department of Health and Human Services (HHS) with a scientifically robust definition of sex and the sexes: male and female. This reaffirmation of biological reality sent left-wing media into a frenzy, unleashing a flood of articles attempting to deconstruct and redefine sex through the lens of progressive queer ideology.

The Society for the Study of Evolution quickly issued a statement, purportedly on behalf of all 3,500 of its members, claiming that the executive order’s recognition of the sex binary “is contradicted by extensive scientific evidence,” and, remarkably, even invoked the subjective “lived experience of people” as part of their counterargument. The Washington Post followed suit on February 19 with an article titled, “Trump says there are ‘two sexes.’ Experts and science say it’s not binary.” A piece in The Hill this week accused the executive order and HHS guidelines of containing “profound scientific inaccuracies,” while Science News proclaimed that “sex is messy” and that “choosing any single definer of sex is bound to sow confusion.” Similar articles challenging the definitions outlined in Trump’s executive order and the HHS guidance have also appeared in Time Magazine, The Boston Globe, Scientific American, The Guardian, and numerous other outlets.

These responses have come in waves, with new attempts to muddy the waters appearing weekly. But one recent article from NPR—“How is sex determined? Scientists say it’s complicated”—encapsulates virtually every fallacious argument and pseudoscientific distortion used in the others. As such, it serves as the ideal target to be used for a collective rebuttal.

He then proceeds with the debunking and ends with this:

The left’s assault on the binary reality of sex is not about science—it is about politics. The goal is to deconstruct and redefine fundamental biological truths to serve ideological ends, whether that be justifying the inclusion of males in female sports, allowing men into women’s prisons, or pushing irreversible medical interventions on children under the guise of “gender-affirming care.”