If ever there were a headline designed to get my dander up, it’s this one from a San Francisco Chronicle op-ed (click screenshot below to read, or see it archived here).
The author’s self-description from the article (below) indicates a non-binary gender, and you can see Zemenick’s webpage here.
Ash Zemenick received their doctorate from UC Davis in 2017 and is the lead director and creator of Project Biodiversify and manager of UC Berkeley’s Sagehen Creek Field Station. Project Biodiversify (www.projectbiodiversify.org) runs workshops on inclusive teaching and develops teaching content to diversify biology education.
(Zemenick was also first author of that Bioscience paper that we had a dust-up about because of its insistence that we teach the sexual diversity of nature before we teach any generalizations.)
The headline above is a lie, at least as far as sex is concerned. While I’m prepared to admit that gender is a spectrum, it’s still bimodal, in that most people cluster around male-like or female-like clothing and behavior, but there are genders between those camel-like humps.
But sex—yes, sex is indeed a binary, and the only reason one would deny that, given the way we biologists define sex, is for ideological reasons. I’m not going to try to fathom why Zemenick wrote this annoying piece, which is filled with folksy but patronizing prose like addressing the readers as “friends,” and “I’m so sorry but nah” when dismissing the claim that genitals are binary (they’re pretty close to it, actually). Stuff like the sentences below grate on me, and would even if they were true:
Now, let’s consider the most reductive definition of sex. The gametes. What are gametes? Reproductive cells. Eggs and sperm. Sounds binary, right? As a human, you either produce eggs or sperm, yeah? Nah.
Not nah, yeah. Zemick even falls for the bogus criticism that sterile or pre- or post-reproductive people are neither male nor female:
Now, let’s consider the most reductive definition of sex. The gametes. What are gametes? Reproductive cells. Eggs and sperm. Sounds binary, right? As a human, you either produce eggs or sperm, yeah? Nah. On average, most cis women and trans guys are born with all of the eggs they may eventually ovulate with. But some are born without them. Some have their ovaries removed. So, they have no gametes. What about them? Cis men and trans women don’t even start producing sperm until the onset of puberty. So, before puberty, they have no gametes. None. Some cis men are sterile. What about them? As you can see, some people, for these reasons, don’t produce or have gametes at all. Therefore, there are three states: no gametes, eggs or sperm. It’s a triplet, a trifecta. Gametic sex is not binary.
That’s bogus. The definition above involves having a developmental system evolved to produce eggs and sperm, not whether it actually does so. This pilpul is simple diversion designed to mislead the reader into thinking that sterile people are a third sex.
And with those words Zemenick dismisses the real definition of biological sex, which is “reductive” whether you like it or not. There are in all animals and nearly all vascular plants just two sexes: males, who have the reproductive equipment to make small, mobile gametes (sperm), and females, who have the reproductive equipment to make large immobile gametes (eggs or ova). That’s all the sexes there are, friends, for nah, there is no third type of reproductive equipment nor any other class of gametes. Humans who don’t fit these definitions are vanishingly rare: about 1 in 6,000. That’s close enough to “binary” for me.
Zemenick could have looked up the definition of sex and educated the reader, but instead they dispel all the folk definitions of sex—definitions based on hormones, chromosome complement, and genitalia, showing that none of these are binary. Well, some of them are almost binary, but it doesn’t matter because these traits are associated more or less closely with sex but are not part of the definition of biological sex. Genitals, for example, are pretty closely correlated with chromosome type (XX or XY) and that with the presence of ovaries or testes, and genitals are often used to diagnose sex at birth, but genital conformation is not the biological definition of sex. I’ll add that biologists defined sex this way years ago not because we were somehow transphobic and wanted to convert what was really a spectrum into an invidious binary, but because this definition is the one that makes evolutionary sense and also helps clarify a host of evolutionary issues, like how sexual selection operates.
I often compare biological sex with biological species. The species definition (or “concept”) that most evolutionists use is that “a species consists of a group of individuals that are reproductively compatible with each other but reproductively isolated (i.e., unable to produce fertile hybrids) with individuals from other groups. (This is called the “biological species concept”, or BSC.) There are of course gray areas, since speciation is a process, but this definition is far more useful than definitions like “a species is a group of organisms that look alike but look different from organisms in other groups.” This is not useful for many reasons, one being that “how different you look” is arbitrary (is an Asian a member of a different species from a European?). Further, there are many real biological species that look so similar that they can’t be told apart except by seeing if they can produce hybrids in nature (these are called “cryptic species”).
Thus the appearance of animals, like the appearance of genitalia, can be a way to diagnose species, but it’s not a good way to define them. Defining species by their reproductive incompatibility is useful because it is the very explanation of why nature forms discrete clusters (reproductive isolation allows groups to diverge in their evolutionary pathways), and the Lumpiness of Nature is the big species problem that Darwin didn’t solve. (It was solved in the 1930s and 1940s by Ernst Mayr and Theodosius Dobhansky, who formulated the BSC). The BSC allows us to tackle this once-intractable problem, and has produced a rich research program, a program not engendered by any other species concept.
My friend Phil just reminded me of another important example showing the difference between definition and diagnosis, one suggested by the great paleontologist G. G. Simpson in 1959. Here’s what Simpson said, drawing an analogy with the BSC:
In the new systematics, a taxonomic group (taxon) is a population and is defined as such. It cannot, by its nature, have a type, either as a concrete individual or as an abstract plan. It embraces all individuals of the population, and furthermore the individuals are continuously changing. It has a pattern, but the pattern is one of development and variation, for only such a pattern can in fact include and characterize the totality of a population. And all taxa are genetical units, defined by their reproductive relationships although they are usually recognized by physical characteristics. That distinction, perhaps esoteric at first sight, may be clarified by the analogy of identical twins: we recognize their relationship by the fact that they look alike, but they are not twins because of their resemblance, which is a result of the reproductive relationship that defines the twin- ship. The primarily genetical definition of taxa is a logical step from Darwin’s explanation of the morphological characteristics of taxa, but its full genetical understanding was beyond possibility for anyone in Darwin’s time.
In other words, the definition of identical twins is “two individuals who came from the splitting of a single fertilized egg”. They are recognized by their physical near-identity, but that recognition can be wrong since some same-sex fraternal twins have been misidentified as identical twins. The egg-splitting definition gets precedence because it’s more explanatory. In the same way, the gametic definition of sex helps clarify and explain a number of sex-related phenomena.
But I digress again; after all, speciation was my field. The point is that diagnosing species status or one’s biological sex can use traits different from those used to define biological species or biological sex. And sex is not “assigned at birth”, but rather determined at birth—in rare instances wrongly when doctors use genitalia—for the existence of a sex binary is a biological phenomenon that can be diagnosed by looking at the reproductive equipment (by that I mean testes or ova). Biological sex is not a subjective position on a continuum pinpointed by doctors, even if they usually do it by looking at whether the newborn has a penis or a vagina.
Zemenick dismisses the other ways sex is defined by laypeople—hormones, chromosome complement, genitalia—as nonbinary, and to some extent Ash is right. These are bimodal (in the case of genitals almost completely so), but not as binary as is sex itself—defined properly. But Zemenick’s whole op-ed simply knocks down a series of strawmen: definitions of sex that no real biologists hold. I’m not going to go through criterion by criterion; you can read the piece for yourself, and perhaps look at articles like this one or this one.
One more point. Here’s the way Zemenick ends the piece:
Now, you may still be disagreeing with me. You might be thinking that the binary definitions of biological sex are the true definition and that the variations I’ve described are just “exceptions to the rule.” I challenge you, though — how good of a definition of biological sex can it be if it does not capture the lived biologies and experiences of millions of humans? I argue that my definitions of biological sex, each one I’ve provided, are more biologically accurate than a binary view of sex, no matter the definition you choose — they more fully encapsulate the truth of nature and humanity.
So, dear reader, next time someone asks you if sex is binary, ask them, “How are you defining sex?” If they can’t answer, explain to them the different ways we can define biological sex. Explain that, no matter how you define it, biological sex is nonbinary.
True, animals don’t have gender the way humans do because they don’t reflect on how they “feel”, whether they don’t feel like either males or females, or feel like something else, or change the way they conceive of their gender from day to day. But animals do have biological sexes, and they are always two. Sex is a biological fact, not an attempt to “encapsulate the truth of nature and humanity” nor to “capture the lived biologies and experiences of millions of humans.” Lived experience has absolutely nothing to do with biological sex. That’s why zebras and fruit flies and ostriches—indeed, all animals—have a sex binary, though few of these creatures (or any plants) even have the ability to “reflect on their lived experience.”
I object to pieces like this because they are biologically inaccurate and probably deliberately misleading, designed to promote a preferred ideology. And they damage the public understanding of science in a way that no non-scientist can, because these declarations carry the authority of the scientist. (Zemenick begins the piece by saying of the sex binary: “As a doctorate-carrying scientist, however, I attest that this is false.”)
Well I carry a doctorate, too (it’s actually somewhere in my office), and I attest that the binary of sex is real.