Image: A grin without a cat. Cheshire Cat, from Alice in Wonderland, illustration by John Tenniel, public domain.
“Well! I’ve often seen a cat without a grin,” thought Alice “but a grin without a cat! It’s the most curious thing I ever saw in my life!” (Lewis Carroll, Alice’s Adventures in Wonderland)
As you’ve probably read here on Scientist Sees Squirrel, I’m writing a new book. It’s about the Latin names of plants and animals (and I promise, it’s a lot more interesting than it sounds). And in thinking and writing about naming, I’ve come to realize that the way we do biological nomenclature leads to the production of some truly bizarre entities: names without things. Let me explain.
Things without names are a perfectly normal category – even if individual instances of the category tend to be short-lived, because we humans really, really like to name things*. We name babies as they’re born, gizmos as they’re invented, mountains and rivers as we discover (or rediscover) them. In science, there’s no busier job of naming than in taxonomy: we share our planet with somewhere between 3 and 300 million living species**, only about one million of which have been discovered, described, and named so far. That leaves between 2 and 299 million things without names – and that’s irksome, to be sure, but it’s nothing outside our ken.
But there’s an interesting way in which taxonomy produces names without things, and that’s a little harder to wrap one’s head around. When someone proposes a new species name, they’re claiming that it’s needed because the specimens on their benchtop don’t belong to any previously named species. If that’s true, there’s no problem: a new entity has been discovered (a species***) and it now bears a name. But what happens when it isn’t true?
Consider this example. In 1990, an entomologist (Kurt Johnson) published a revision of the Neotropical butterfly genus Calycopis. The result was a dramatic splitting up of the group and a profusion of new names, with 235 claimed species spread across 20 genera. Among the new genera was Serratoterga, and among the new “species” was one named for the cartoonist Gary Larson: Serratoterga larsoni****. But 14 years later another entomologist, Robert Robbins, published his opinion that Serratoterga larsoni isn’t a distinct species at all. Instead, the butterflies Johnson called S. larsoni belong to the very familiar species Calycopis pisis. This is now the entomological consensus: Johnson’s naming of S. larsoni wasn’t necessary because the butterflies in question didn’t, after all, belong to newly discovered, distinct species.
Where does that leave the name Serratoterga larsoni? It leaves it something decidedly peculiar: a name without a thing. “S. larsoni” as a name doesn’t apply to something distinctive, as Johnson meant it to. But it also doesn’t quite refer to something familiar – because despite being technically called a “junior synonym” of the older name Calycopis pisis, it really isn’t a synonym in the usual sense of the word. That’s because Johnson’s description of S. larsoni fits some individuals of Calycopis pisis (including, most obviously, the one Johnson designated as the claimed species’ holotype), but it doesn’t fit them all. It’s as if someone proposed the name Homo elevator for all humans taller than six feet. That set of people isn’t (of course) a separate species, so the name H. elevator would be a junior synonym of the older name Homo sapiens. But “synonym”? The description that goes with Homo elevator applies to me but not my wife, to James Taylor but not Paul Simon, to Larry Bird but not Isaiah Thomas. It’s a synonym in the technical taxonomic sense; but in any other sense, it’s clearly not.
So the name Serratoterga larsoni is a name without a thing. It will never be used to designate anything else (under the rules of biological nomenclature), but the thing it was intended to designate doesn’t exist. In Alice’s Wonderland experience, it’s a grin without a cat. And it isn’t alone in its weirdness: the kind of error-and-correction that happened to Calycopis is far from uncommon, and it isn’t even the only way that junior synonyms are generated.
“Wait”, I can hear you saying, “there’s nothing special about junior synonyms; there are plenty of names without things”. You might point out that we’ve named plenty of things that turned out not to be real: unicorns, Tatooine, the ether. But a unicorn (let’s tackle that one) is a thing that happens not to exist, while S. larsoni isn’t a thing in the first place. I admit that’s a subtle philosophical distinction, so let me put it a slightly different way. “Unicorns” exist as a class, in the sense that we have a very clear picture of what one is and how we’d recognize it; it’s just that no real individuals belong to the class. S. larsoni (like its synonymic kin) is the other way around: at least one individual butterfly belongs to the class (the holotype Johnson designated), but the class doesn’t actually exist. There’s nothing for the name “S. larsoni” to refer to (because the whole point of conferring the name is to recognize the existence of S. larsoni as a species, and it isn’t). It’s a name without a thing.
Does your head hurt now? Mine does.
© Stephen Heard July 17, 2018
*^In the Old Testament creation story, Adam’s very first job was to assign name to Earth’s creatures: “And out of the ground the Lord God formed every beast of the field, and every fowl of the air; and brought them unto Adam to see what he would call them: and whatsoever Adam called every living creature, that was the name thereof.” (Genesis 2:19, King James Version). I mean, he hadn’t even had lunch yet.
**^Yes, it’s professionally embarrassing to write that sentence. Nobody knows where in that range the real total sits, although some recent efforts to narrow it down come out around 8 million.
***^There are fervent disagreements about how to define species; but nearly everyone believes that they exist.
****^It’s one of two species (to my knowledge) named for Larson. The other, the feather louse Strigiphilus garylarsoni, became famous when Larson included it in his compilation Prehistory of the Far Side. You can read the whole story in my new book – once I’m finished writing it.