Rejecting the Sex Binary with Bad Evidence

In a Scientific American article, Princeton anthropologist Augustin Fuentes argues that “binary and simplistic explanations for human sex biology are either wholly incorrect or substantially incomplete.” To support this claim, he points to worms that produce both sperm and eggs and fish that switch from one sex to another. Alan Shlemon, host of Thinking Out Loud, takes this argument apart piece by piece, showing why evidence from radically different species cannot justify rejecting the sex binary in humans.

The Two Pillars of Transgender Ideology

Shlemon begins by clarifying the framework he is critiquing. Transgender ideology, he says, rests on two foundational pillars that must both be true for the ideology to be coherent. The first is gender identity—a person’s deeply held internal sense of being male, female, both, or neither, which can be incongruent with biological sex. The second is the sex spectrum, the claim that biological sex is not a binary (male or female) but a continuum, and that humans can fall anywhere along it or even change their sex.

Shlemon sets aside the gender identity pillar and focuses entirely on the sex spectrum argument, specifically the version advanced by Fuentes.

The Evidence: Worms and Clownfish