NOTE: Society is coarse nowadays. What is Not Safe For Work (NSFW)? When everything goes, maybe nobody cares? Regardless, this brief essay is about sex, the language we use to describe reproduction. Human sexuality typically makes for mature reading. Depending on your workplace—perhaps this is fine for a medical office, but you know, hold off if you’re teaching Pre-K—you might want to read this in a more private setting.







We start with biology. Or, rather, we’d like to start with biology. I’d love to start with biology. Why can’t we start with biology? Well, because in today’s world, we can’t even agree on that. I’m going to do the following: (1) provide a loose definition of the sexes that agrees with traditional biological understanding; (2) dig deeper into the science of how human being reproduce and talk about how that determines the definition of sex; and (3) refute the arguments for a third sex or non-binary (which often substitutes ideology for fact). But before we get there, I need to talk about science (yay!) and politics (meh





Science gets attacked. Look at climate change deniers. Look at anti-vaxxers. Look at any almost any scenario where science doesn’t fit someone’s political agenda. This is demonstrably bad, from disease outbreaks to the ongoing heating of the planet. For as the famous physicist Richard Feynman wrote in his NASA review after the Challenger disaster, “…reality must take precedence over public relations, for Nature will not be fooled.” Feynman was talking about technology, but the broader theme about science is just as applicable: Either we can accept science fact or we will suffer the consequences.

Biological truths should not be contentious. But my own experience differs. I’ve found that often a person’s political position determines their acceptance of the science. I’m not alone in this. When Steve Jacobs, Ph.D., conducted a survey of some 5500 biologists, 96% responded that human life begins at fertilization (Jacobs, Steve. “I Asked Thousands of Biologists When Life Begins. The Answer Wasn’t Popular.” Quillette, 16 Oct. 2019, By itself this is neither surprising nor remarkable—we’ve known this for years. Overlay the abortion debate (especially when Roe v. Wade itself suggests there is no consensus on “the difficult question of when life begins”), and oh boy. Alexa, order more popcorn.

So the political implications are not lost on me. I want to be clear this is an essay about sex, something grounded in hard science, and not gender, which is not necessarily biologically based and is considered a social construct. For some, this won’t matter. They are going to see red no matter what. But when science itself becomes “hate speech,” we are all imperiled.

Woman (n): Adult human female.
Man (n): Adult human male.

That these two loose definitions should prove controversial in today’s world would gob-smack any scientist or biologist from earlier generations. Frankly, the vast majority of today’s scientists and biologists can’t believe it. You will find no peer-reviewed scientific paper that claims human beings have more than two sexes, and as you might expect, there’s a good reason for that.


But even popular scientific periodicals have now published non-peer reviewed articles which are, politely stated, politically driven. Does the scientific community have a response? Yes. Yes, they do.





















Attempts to recast biological sex as a social construct, which then becomes a matter of chosen individual identity, are wholly ideological, scientifically inaccurate and socially irresponsible.

Project Nettie









































As I’ve said, science—our attempt to systematically study and understand the nature of the reality we find ourselves in—must take precedence over personal desire or politics. For example, if I ask the question, “What is a woman?” science provides a ready answer. This contrasts sharply with those not basing their answers in biology, many of whom stumble all over themselves trying to be politically correct or who resort to no answer at all. (Responses I’ve seen include: “Anyone can be a woman,” “A woman is a state of mind,” and “That’s a really good question.”)





















Male and female describe sexual roles. They’re about how we reproduce. That is what sex is about in a biological sense, and all other definitions of sex (legal, psychological, medical, etc.) are based or should be based on this understanding.





















Here’s the biology: In mammalian reproduction there are two gamete types, large (ovum) carried by the female and small (sperm) carried by the male. The fusion of these two gametes—called anisogamy—is what forms a zygote and begins new human life.Want more detail? Here’s Human reproduction at Wikipedia: Crucially, there is no third gamete type. In fact, no anisogametic species produces a third gamete type. There are exactly two reproductive roles in anisogametic reproduction—male and female—which is why sex is binary, not a “spectrum,” and “non-binary” as a sex descriptor makes no sense.





















Biological arguments for a “non-binary” category typically involve individuals with intersex conditions, chromosomal abnormalities, or infertility issues. I have seen these arguments made in good faith by reasonable people. They’re wrong, but understandably so, and therefore it’s worth taking them each in turn. (I’ve also seen them made in bad faith by utterly unreasonable people, but those folks have already stopped reading or are busy composing emails or tweets that conflate sex with gender identity.)





















In the case of hermaphrodites (more frequently today called “intersex”), we might see both male and female or ambiguous genitalia. This is a rare condition, but given some 7.6 billion people in today’s world, it would be remarkable if we did not see some variation like this. Whether intersex is a disorder of sex development, as some argue it is, is immaterial here. Variation in human beings does not mean that a third sex exists. Just as a person might be born without legs, that doesn’t mean we’re not a bipedal species. In no circumstance does an intersex individual produce a third gamete type. In fact, most intersex are infertile. Not that opinion should have bearing on the science of it, but it is notable that intersex advocates and organizations themselves are adamant that their condition does not constitute a third sex. (Learn more about Intersex and related conditions at LOCAH’s “The Intersex Masterpost” (





















Likewise, there may be mixed XX and XY chromosome pairs or other chromosomal abnormality. Again, there is no third gamete type. No human being, whatever their chromosomal make-up, generates a third gamete for reproduction. None. And no human being generates both gamete types. Chromosomal abnormalities may make it difficult to observe biological sex, but most of these (extremely rare) conditions are actually male or female specific. In no case does this represent a third sex. Or, as I heard it once said rather poetically: That twilight exists does not negate the day or the night.





















Infertility has always struck me as a strange argument. Surely it is clear that, say, a post-menopausal woman is still a woman? Apparently the idea is that because a post-menopausal woman no longer produces eggs (gametes) she is no longer a woman. What’s being described is, of course, a condition. If my reproductive system is geared toward producing small gametes (sperm) but I produce none, it’s not that I’m not male. It’s that I have a condition that prevents that gamete production. In the case of post-menopausal women, that condition is understood to be absolutely normal for our species. It should, I hope, be obvious that this does not constitute a third sex, since the definition of infertility means being unable to reproduce.





















The final argument I’ve heard is definitional. That is to say that sex is not “binary” but rather “bimodal.” Sex certainly is bimodal, which means “having or involving two modes, in particular (of a statistical distribution) having two maximaI used Apple’s built-in dictionary for this. Others will give roughly the same definition.” Those two maxima are, of course, male and female. You’ll have a small sprinkling of intersex, but that’s it. Here’s how Colin Wright, a research fellow at Penn State, and Emma Hilton, a developmental biologist at the University of Manchester, explained it:





















There is a difference, however, between the statements that there are only two sexes (true) and that everyone can be neatly categorized as either male or female (false). The existence of only two sexes does not mean sex is never ambiguous. But intersex individuals are extremely rare, and they are neither a third sex nor proof that sex is a “spectrum” or a “social construct.” Not everyone needs to be discretely assignable to one or the other sex in order for biological sex to be functionally binary. To assume otherwise — to confuse secondary sexual traits with biological sex itself — is a category error.

Wright, Colin M., and Emma N. Hilton. “The Dangerous Denial of Sex.” The Wall Street Journal, Dow Jones & Company, 13 Feb. 2020,





















We are wonderfully diverse creatures. Indeed, each of us is unique. We are worthy of respect and celebration, perhaps all the more because we spring from one of two biological templates. That our sex is both binary and immutable is a severe disappointment to some. But it is the biological reality, and like all science, we are better off when we accept it. Indeed, we ignore science at our peril.