“What would happen if suddenly, magically, men could menstruate and women could not?” With this question posed at the outset of her famous essay If Men Could Menstruate, Gloria Steinem imagined a society in which men would make periods an “enviable, worthy, masculine event.” Rather than being seen as an embarrassment or something to hide, “that time of the month” would become a sign of courage in patriarchal societies, she argued. Scientists would prioritize researching the origin of stomach cramps over heart attacks, from which menstruating men would be hormonally protected. All in all, what many societies have traditionally deemed dirty would instantly become an element of pride.

Though fictional, Steinem’s essay allows readers to take in one simple truth: Dirt, and inde...