Evolution is slow, but powerful. Billions of years gradually molded single celled organisms into dogs, tardigrades, and Ted Cruz.(It’s got its quirks).
I enjoy wondering how different things are in the corner of the multiverse where we evolved from the critter with seven sexes. Mainly for the twitter arguments.
Today’s Moment of Science… Seven sexes for seven siblings.
People are super fucking focused on if there’s any room between a binary or not. As though ‘man’ and ‘woman’ is all there ever has been and all there ever will be in our species and any species. Pffft.
Meet the Tetrahymena thermophila. It sees your binary sexes and raises you septenary sexes. Septenary, as in no fucking kidding seven sexes. It lives in freshwater and, under a microscope, you can see the tiny hair-like projections called cilia that make it vaguely resemble a tiny cactus. Or hairy balls, I haven’t decided.
Their names are I, II, III, IV, V, VI, and VII. Bursting with creativity in the lab that day, I see. The only biological guardrail on mating is that they can’t produce offspring with their own mating type.
Out in the animal kingdom we have Z0, X0, and ZW along with XY sex determination systems. But that’s dreadfully boring. There’s no simple name for the allele based sexual determination system used by T. thermophila. A II and a VI could get together and swap DNA, you’re not necessarily getting another II or VI, and nobody’s asking to see a T. thermophila paternity test.
How does this happen? Scientists have known about the creature’s unique sexual characteristics since the 1930s, but only elucidated the process behind it recently. An itsy nutsack protozoan passes on an incomplete set of genes based on their mating type. Mating with an organism of any other sex enables the pair to pass on a complete set of genetic information, able to create any of the seven sexes. The DNA then goes through what’s currently understood to be a random process of fragments rearranging and deleting until one sex remains in their offspring.
There’s sort of an exception to the “won’t reproduce with any of its own type of sex” rule. That’s when it reproduces asexually. It’s one of those resourceful critters in the animal kingdom that’s going to pass its genes on any goddamn way it feels like. When resources are plentiful, it tends to reproduce asexually, switching to sexual reproduction in times of scarcity. It’s suspected to be an instinctive tactic to tap into genetic biodiversity for survival.
Evolution produced covid, Ted Cruz, and this adorable little septenary sexed scrotum that can fuck itself for survival. Quirks, man.
This has been your daily Moment of Science, suggesting that these free spirited eukaryotes deserve better names.
For more info on critters in the animal kingdom that say ‘fuck the gender binary,’ check out this video from my friend Dr. Abby Hafer. Her talks are brilliant:
For exclusive bonus content and stories of banging protozoans, horny dolphins, and that time Australia went to war with the emus sent straight to your inbox, head to patreon.com/scibabe).
Suggested sex names: Up, Down, Top, Bottom, Charmed, Strange, and Pat.