As a child, I had a book that described the differences between numerous common animal categories. It provided two-page spreads, lavishly illustrated, narrating the differences between frogs and toads, salamanders and newts, snakes and lizards, turtles and tortoises, whales and dolphins, whales and fish, and more. Each was authoritative, each was simple, and each, I would later learn, was either only superficially correct or outright wrong. Deeper exploration of these animal groups shows how these basic dualities offer little explanatory power or understanding and reveal more about us than they do about the world. Biology does not deal in dualities, and classification in particular finds them quaint and obsolete.
So, let’s dive into a few of them.