Colin Wright gives a history of the gametic definition of biological sex

As everyone knows, I adhere to the gametic definition of sex, in which individuals are classified as male or female (or, as in hermaphroditic plants, both sexes in one individual) based on whether their bodies are set up to produce small, mobile gametes (the “males”) or large, immobile gametes (the “females”).  I’ve explained why I adhere to this definition, because it is not only universal in animals and vascular plants, but also because the difference between males and females in investment in gametes, which leads in general to females having a greater overall investment in reproduction, explains a lot of puzzles in evolution. One of them is why sexual selection creates males and females who are often so different in color, size, weaponry, and so on. Just remember: universality and utility.

Here’s a more formal definition given by Colin Wright write in his new post on his website, Reality’s Last Stand.

In biology, the definition of male and female has never been arbitrary or culturally relative. It is grounded in the concept of anisogamy: the existence of two distinct types of gametes—sperm and ova. This fundamental reproductive asymmetry defines the two sexes across all sexually reproducing anisogamous species. An individual that has the function to produce small, motile gametes (sperm) is male; one that has the function to produce large, immobile gametes (ova) is female. This is not a social construct or a philosophical preference—it is a basic principle of evolutionary biology, established long before today’s cultural debates.

Now of course this definition wasn’t pulled out of thin air: it is an a posteriori conclusion about how nature is set up. It is a truth that all animals and vascular plants have only two sexes, male and female, though in some species, as I said, individuals can be of both sexes. (And some individuals, like clownfish, can change their gametic sex.) But there is no third sex, no matter how hard the ideologues squeal about seahorses, clownfish, and hyenas. There is no third type of gamete in any species.  In fact, the opposition to the binary nature of sex by gender ideologues have led some of them to argue that the gametic definition of sex is a recent confection sneakily devised by “transphobic” biologists who want to shoehorn all people (and animals and plants, apparently) into two categories. Colin wrote the piece below to show that this claim is false. The gametic definition has been around for about 140 years.

Click on the screenshot below to read the piece (Colin’s bolding).

Now I make no claim that the gametic definition of sex is universal among evolutionary biologists, much less all biologists. I haven’t taken a poll! But the biologists I’ve encountered in my own field almost universally adhere to that definition. At any rate, Colin goes way back in the past to show a passel of biologists (I know many of the more recent ones) who adhere to and have presented the gametic definition of sex. As Colin says:

The historical and scientific record is clear: from the 19th century to the present day, biologists, medical professionals, philosophers of science, and evolutionary theorists have used gamete type as the defining criterion for sex. This document compiles citations from that record, providing a reference point for students, scientists, educators, and anyone interested in understanding what “male” and “female” mean in biological terms.

These citations span more than a century of scientific literature, showing that the gamete-based definition of sex is not a recent invention or a reactionary response, but a longstanding, fundamental biological principle. While sex roles and secondary sex characteristics can vary, the definition of the sexes does not: male and female are reproductive categories rooted in the type of gamete an individual has the function to produce.

This document is a work in progress. If you are aware of additional scholarly references—especially historical ones—that clearly depict the gametic definition of sex, please share them in the comments so I can continue to expand and improve this resource. I encourage readers to bookmark this page and return to it often as a reference in conversations, research, and advocacy.]]

I think I sent him the Futuyma reference (not below), but I can’t remember. At any rate, you can read them all yourself, but I’ll put up five of them spaced apart, starting with the first one in 1888. These are from Colin’s piece:

1888 – Charles Sedgwick Minot. “Sex,” in A Reference Handbook of the Medical Sciences Embracing the Entire Range of Scientific and Practical Medicine and Allied Science, Vol. 6, Alfred H. Buck (ed.) (New York: William Wood and Company), 436-438

As evolution continued hermaphroditism was replaced by a new differentiation, in consequence of which the individuals of a species were, some, capable of producing ova only; others of producing spermatozoa only. Individuals of the former kind we call females, of the latter males, and they are said to have sex.

1929 – Horatio Hackett Newman. Outlines of General Zoölogy (New York, The Macmillan Company), p. 448.

Any individual, then, is sexual if it produces gametes—ova or spermatozoa, or their equivalents. Thus we would be justified in calling any individual that produces ova a female, and one that produces spermatozoa a male. One that produces both kinds of gametes is a male-female or, more technically, a HERMAPHRODITE. Thus we may say that the PRIMARY SEXUAL CHARACTERS of individuals are the ova or the spermatozoa, and that maleness or femaleness is determined by the possession of one or other of these two types of gametes.

A ringer: Simone de Beauvoir!

1949 – de Beauvoir, Simone. The Second Sex, translated by H.M. Parshley (New York: Vintage Books), 39

In the vast majority of species male and female individuals co-operate in reproduction. They are defined primarily as male and female by the gametes which they produce—sperms and eggs respectively.

2013 – Roughgarden, Joan. Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press. [Note: Roughgarden is a trans-identifying male]

To a biologist, “male” means making small gametes and “female” means making large gametes. Period! By definition, the smaller of the two gametes is called a sperm, and the larger an egg. Beyond gamete size, biologists don’t recognize any other universal difference between male and female.

2021 – Bhargava, Aditi, et al. “Considering sex as a biological variable in basic and clinical studies: an endocrine society scientific statement.” Endocrine Reviews 42.3: 219-258.

The classical biological definition of the 2 sexes is that females have ovaries and make larger female gametes (eggs), whereas males have testes and make smaller male gametes (sperm); the 2 gametes fertilize to form the zygote, which has the potential to become a new individual. The advantage of this simple definition is first that it can be applied universally to any species of sexually reproducing organism. Second, it is a bedrock concept of evolution, because selection of traits may differ in the 2 sexes. Thirdly, the definition can be extended to the ovaries and testes, and in this way the categories—female and male—can be applied also to individuals who have gonads but do not make gametes.

So much for those chowderheads who say that, using the gametic definition, neither a pre-puberty human, a postmenopausal woman, or a sterile person can be male or female. If you see this argument, you know you’re dealing with someone who’s intellectually dishonest.

Again, this is not a vote to see how many biologists (or feminists!) would define biological sex. It is meant, as Colin said, to show that the gametic definition of sex has been around for well over a hundred years.