The Natural Desire for Sexual Identity Is (Mostly) Binary

 

                                            The Binary Sexual Reality of Two Kinds of Gametes

I have argued that the natural desire for sexual identity as either male or female is one of the twenty natural desires of our evolved human nature.  But even as I stress the dualism of sexual identity as male or female as the biological central tendency of our human nature, I recognize the variation from this strict bipolarity--such as true hermaphrodites who combine both sexes, other kinds of intersexual people, and people who are transgender in crossing from one sex to another.  

The natural desire for sexual identity is mostly binary.  For most of us, our biological sex is clearly male or female.  And for most of us, our gender identity corresponds to our sexual identity as male or female.  But in rare cases, an individual's sex is a biological mosaic of male and female traits.  And in some cases, an individual's gender identity diverges from his or her biological sexual identity.  I have written about this here, here, here, and here.

I was recently prompted to think more about this as I read an article in Skeptical Inquirer by Jerry Coyne and Luana Maroja on "The Ideological Subversion of Biology."  They consider six examples of how "progressive social justice" denies the truths of biology.  The first example is the popular claim that "sex in humans is not a discrete and binary distribution of males and females but a spectrum."  They reject this:

"This statement . . . is wrong because nearly every human on earth falls into one of two distinct categories.  Your biological sex is determined simply by whether your body is designed to make large, immobile gametes (eggs, characterizing females) or very small and mobile gametes (sperm, characterizing males).  Even in plants we see the same dichotomy, with pollen producing the tiny sperm and ovules carrying the large eggs.  The size difference can be huge: a human egg, for instance, has ten million times the volume of a single sperm.  And each gamete is associated with a complex reproductive apparatus that produces it.  It is the bearers of these two reproductive systems that biologists recognize as 'the sexes.'

"Because no other types of gametes exist in animals or vascular plants, and we see no intermediate gametes, there is no third sex. . . ." (35).

Although I generally agree with everything they say, I would emphasize the significance of the adverb in the first sentence: "nearly every human on earth falls into one of two distinct categories."  Coyne and Maroja admit that a few human beings cannot be clearly identified as either male or female.  In some previous posts, I have commented on Anne Fausto-Sterling's claim that there are at least five human sexes.  In addition to males and females, there are three other sexes.  True hermaphrodites ("herms") have both male chromosomes (XY) and female chromosomes (XX); and consequently, they have can have one testis and one ovary, or a fusion into an ovotestis, and they might have a vagina with a large clitoris that at puberty grows to the size of a penis.  Female pseudohermaphrodites ("ferms") have ovaries and female chromosomes (XX), but they might have beards, what looks like a penis, and other apparently masculine traits.  Male pseudohermaphrodites ("merms") have testes and male chromosomes (XY), but they might have a vagina, a clitoris, and breasts.  Merms and ferms are intersexual individuals whose sexual development has deviated in some way from that of a typical male or typical female.  This includes various disorders of sexual development that create anomalies in the sex chromosomes, the gonads, the reproductive ducts, and the genitalia.  For example, Caster Semenya of South Africa, who won the 800 meters race for women at the Rio Olympics in 2016, is probably a chromosomal male (46 XY) who was born with sexually ambiguous sex organs, and who was raised as a girl, despite being biologically male.

While Coyne and Maroja recognize these anomalous cases of confused sexual identity, they deny that these represent "other sexes."  They insist that there can only be two sexes--male and female--because these are the two reproductive systems designed by evolutionary natural selection.  The male reproductive system contributes sperm to the reproductive process, while the female reproductive system contributes eggs.

One can see this in hermaphrodites, they argue.  Most hermaphrodites are infertile.  But in those few cases where hermaphrodites are fertile, they must be fertile as a male (Parvin 1982) or as a female (Schoenhaus et al. 2008).  In the one case, a phenotypically male fertile hermaphrodite fathered a child by impregnating a woman with his sperm.  Remarkably, blood tests showed that 81 per cent of his cells were 46 XX, and 19 per cent were 46 XY.  He was a biological chimera who had arisen from the fusion of an XX zygote and a XY zygote.  In the second case, a phenotypically female hermaphrodite gave birth to a child after being impregnated by a man.  Blood tests showed that 96 per cent of her cells were 46 XY, and 4 per cent were 46 XX.  She was probably a biological mosaic arising from a mutation in one zygote.

That human beings must be fertile either as a male or as a female proves that male and female are the only sexes, Coyne and Maroja suggest, because reproduction is the only natural function of sex.

But as I have argued in my posts on animal homosexuality, sex has other natural functions beyond reproduction.  Pair-bonding, for example.  Heterosexual and homosexual couples have a natural desire for sexual bonding even when they are infertile.  And while sexual pair-bonding often promotes reproduction and parental care of offspring, it can be a naturally desirable good in itself.

REFERENCES

Coyne, Jerry A., and Luana S. Maroja. 2023. "The Ideological Subversion of Biology." Skeptical Inquirer 47 (July/August): 34-47.

Parvin, Simon D. 1982. "Ovulation in a Cytogenetically Proved Phenotypically Male Fertile Hermaphrodite." British Journal of Surgery 69: 279-80.

Schoenhaus, Samantha A., Scott E. Lentz, Peter Saber, Malcolm Munro, and Seth Kivnick. 2008. Fertility and Sterility 90 (November): 2016.e9.