I’ve recently found myself wanting to explain evolution to the many strangers who don’t get it, so I started writing. The general public, it seems, thinks the Theory of Evolution is a lot less legitimate than it really is. We’ve got evidence in spades, and it makes a lot of useful predictions. The irony, in my opinion, is that as flimsy as people think evolution is, people also believe that “species” is a well-defined, even immutable, concept. Darwin wrote in 1859, in On The Origin of Species: