“Alien Invasive Species”

The Polish Academy of Sciences maintains a database of invasive species, with over 1700 entries. Earlier this week, Felis catus — the domesticated house cat — was added to the list.

This, of course, has caused certain regions of the internet to lose their damn minds. We love cats; how could anyone call them such dirty names as invasive or alien?

Well: scientists. Sorry about that. Let me try to explain why this is accurate and helpful, not offensive or cruel.

Let’s start by defining cat. I’ve written about the difficulty of defining species before, and cats have an interesting history, here.

We all know what I’m talking about: smallish furry critter, quadruped vertebrate mammal, carnivore and hunter, retractable claws — there’s over 50 breeds recognized today. But what is the scientific name for these delightful little beasts?

A cat! Puig sure looks like a Siamese, but since she was a street mutt from Lubbock, Texas, she’s almost certainly not. There’s a company that will do a breed analysis for a few hundred bucks, but it seems like — how should I say — a giant waste of money. Photo by author.

In 1758, Carl Linnaeus names the common domestic house cat Felis catus. In 1777, Felis catus domesticus was proposed, but since we call this branch of science Linnaean Taxonomy for a reason, Linnaeus’s version was more popular.

The International Commission on Zoological Nomenclature confirmed the Linnaean name for house cats in 2003. In 2007, though, new genetic evidence suggested Felis silvestris catus was more appropriate, a subspecies of European wildcats. In 2017, the whole family Felidae was revamped, and cats were re-declared Felis catus.

Evolutionarily, cats seem to be descended from Felis silvestris lybica, a Middle Eastern wildcat. That said, the taxa is fuzzy because plenty of wildcats can interbreed. Further confusing the issue, cats seem to have had multiple incidents of domestication, ranging from Asia through the Fertile Crescent into Africa.

Basically, though, the modern domestic cat is a product of the Fertile Crescent, so biologically, any cat outside the Middle East is alien. Not from around here, that is. If I bring an American Bald Eagle to Australia, it’s alien. If I bring kudzu into the United States, it’s alien.

Invasive, on the other hand, implies that it’s got a chance to reproduce like crazy (“prolifically and undesirably”) and cause harm to the native ecosystem(s). Kudzu grows incredibly well in the southern United States.