This is one of the standards of rat lore and science, a concise overview of whats known about this pervasive rodent. Among the more surprising things I learned are the fact that the brown, or Norway rat, wasn’t present in most of the world until very late in the game, arriving in America in the 18th century, and in Europe barely earlier, and that the black, or tree rat, only predates that by a few centuries. It makes perfect sense of course, for the success of both species (and the devastating side effects) is closely linked to human civilization, but is startling nonetheless. Aside from that, the most surprising fact is how little was known about animals as ubiquitous and important as rats even in the 1970s, and I suspect not much has changed since then.