Denying that Sex is Binary: A Study in Hypocrisy

The presidents of three American societies of evolutionary biologists and ecologists have written a joint letter to President Trump and members of the US Congress stating that “extensive scientific evidence” contradicts the view that “there are two sexes . . . [which] are not changeable.” Also the view that “sex is determined at conception and is based on the size of the gamete that the resulting individual will produce”. Their statement is false and their letter is riddled with hypocrisy. In my opinion Donald Trump is a loathsome individual, utterly unfit to be President, but his statement that “sex is determined at conception and is based on the size of the gamete that the resulting individual will produce” is accurate in every particular, perhaps the only true statement he ever made.

The fact is, of course, that paper after paper in the scientific literature refers without qualification or equivocation to “males” and “females”. Biologist authors correctly assume that their readers will know the meanings of  “male” and “female” without further explanation, and will accept the authors’ unsubstantiated recognition of the sex of the animals they study. I shall quote just three examples, which happen to be papers authored by Carol Boggs, Daniel Bolnick and Jessica Ware, the three society presidents. A conceivable riposte would be that “humans are not animals”. But then at what point in the evolution of Homo sapiens did sex suddenly became non-binary, a single exception to the general rule pervading the whole of the animal and plant kingdoms? And indeed, the three presidents explicitly disavow human exceptionalism when they say, “Such diversity is a hallmark of biological species, including humans.”

By signing off as presidents of their respective societies, the three give the false impression that they speak for their members, members who were not consulted and not complicit in the hypocrisy of the letter. An ad hoc group of professional evolutionary biologists have signed a disclaimer which includes a space for you to add your name.

My three examples follow (bolding is mine):

1. D R. Chappell*, Carol Boggs and DI Speiser (2023)

Two sides of the same wing: vesntral scales enhance dorsal wing

color in the butterfly Speyeria mormonia

Journal of experimental biology, 226, 1-6.

The paper contains 16 instances of “male” or “female” “males” or “females”. In all cases the meaning of “male” and “female” is assumed without qualification or doubt. Here are the 16 instances.

“We collected females of the silver morph “

“We repeated this process for one marginal orange patch and one submarginal orange patch for one forewing and one hindwing from each of 20 individual female S. mormonia (Fig. 1).”

“The anterior section of a hind wing from a female Speyeria mormonia”

“The orange patches on the wings of S. mormonia (and closely related species) are thought to be used by females for sexual signaling because males are attracted towards orange swatches of similar chroma to the wings of females (Magnus, 1958). Males search for mates during mid-day under open skies by patrolling above the dense vegetation (McCulloch et al., 2017). The bright orange of females’ dorsal wing surfaces may aid in mate detection and be a sexually selected trait. To attract males for mating, females would benefit from wings with large, bright, orange dorsal surfaces. Further, males of closely related species (e.g. Argynnis) seem to choose females based on the size, chromaticity and fluttering rate of their wings, so the visual signal of a female’s wings is presumably an important sexually selected trait (Magnus, 1958). It is likely that females producing brighter and more saturated orange signals will be more quickly detected by patrolling males. Reflections from the silvered scales of butterflies are largely viewing angle independent (Ren et al., 2020; Dolinko et al., 2021), so our findings are relevant to the varied angles at which silver scales will be illuminated and viewed during mating interactions under natural conditions.”

“The broadband reflective silver scales on the ventral wing surfaces of S. mormonia may be a metabolically inexpensive way for nutrient- limited females to boost their sexual signal.”

2. RE Rangel, T Ingram & Daniel Bolnick (2023) Rates of Alloparental Care by Male Stickleback in Natural Lake Populations. Ichthyology & Herpetology 111, 368-375.

The paper contains 169 unqualified instances of “male” or “female”, “males” or “females”.

3. DA Evangelista, K Chan, KL Kaplan, MM Wilson & Jessica Ware (2015) The Blattodea (Insecta, Dictyopea) of the Guiana Shield, Zoo Keys 475, 37-87,

The paper contains 49 unqualified instances of “male” or “female”, “males” or “females”.

When I wrote this, I was unaware that Jerry Coyne had already made the same point, quoting three different papers written by the three society presidents. He was too polite to accuse them of hypocrisy.