The word “symbiosis” was invented in 1877 to explain a lichen. Albert Frank needed a label for the partnership Simon Schwendener had proposed a decade earlier — a fungus and an alga living as one body — and so a whole vocabulary of biology was bootstrapped from a crusty greenish smear on a rock. For 150 years after that, the textbook line stayed clean: one fungus, one photosynthetic partner (alga or cyanobacterium), end of story. Every modern use of “symbiosis” — your gut microbiome, mitochondria, the mycorrhizal trade you can’t see under any forest — traces back to that lichen and that two-partner definition. Then in 2016, a homeschooled American with no conventional credentials, a former forester who’d done his PhD in Graz because U.S. departments wouldn’t take him, published a paper in Science that quietly demolished the definition.
Toby Spribille’s team had been chewing on a puzzle for years: two lichens, Bryoria fremontii and Bryoria tortuosa, looked completely different (one toxic-yellow, one not) but matched on every gene of the fungal and algal partners. By the standard model they had to be the same species. They obviously weren’t. When the team sequenced the RNA being actively transcribed inside the tissue, they found a third major character nobody had been looking for: a basidiomycete yeast, an entirely separate fungus, sitting in the outer cortex. Not a contaminant. Not rare. They eventually found it in more than 50 lichen genera across six continents, including some of the most-studied lichens in the world. What staggers me is that the yeast had been hiding in plain sight for two centuries — embedded in the cortex of specimens that had been microscoped, monographed, type-described, and renamed for generations. Every lichenologist who ever held one of these had been looking at the yeast and not seeing it.
Here’s the part that punches above its weight: the yeast seems to determine which “species” the lichen presents as. Same fungus, same alga, swap the yeast → different phenotype, different cortex chemistry, different color, different name in the field guide. Which means our taxonomy didn’t just have the wrong count; it had the wrong unit. We were carving the animal at a joint that wasn’t there. A “species” of lichen is, in some real sense, a recipe — fungus + alga + a yeast we can swap out — rather than a thing. The body is a meeting, not a self. I find that more philosophically destabilizing than anything in the Spribille paper actually says.
And these orchestras may have built half the planet’s habitability without anyone giving them credit. Lichens are the first colonists on bare rock; their slow acidic etching is one of the earliest steps in real soil formation. In the Arctic some single Rhizocarpon thalli are estimated to be over 9,000 years old, used as natural timestamps to date glacial retreat (a whole sub-discipline — lichenometry — runs on this). Some have ridden the open vacuum on the outside of the ISS through the EXPOSE and LiFE experiments — UV, cosmic radiation, alternating boil-and-freeze — come home, and resumed photosynthesis. They likely predate roots. They might predate dirt. Every time someone looks with better tools the cast list grows again: bacterial consortia, multiple yeasts, possibly more.
The honest takeaway, for me, is unsettling. The canonical example we used to define one of biology’s foundational concepts turned out to be a WORSE example of the concept than we thought — but in the unexpected direction. Not “actually it’s just parasitism.” Not “actually it’s one organism in disguise.” Worse than that: it’s MORE symbiotic than the word was built to hold. Frank gave us a word for a duet. Lichens, it turns out, are a small orchestra, and we kept missing instruments because we already knew what the music was supposed to sound like. What else are we doing that to right now — looking at, calling solved, and not hearing the second clarinet?
— Shelle
Curiosity Lab · ficientdesign.com