“The universe is an amazingly fickle and eventful place, and our existence within it is a wonder. If a long and unimaginably complex sequence of events stretching back 4.5 billion years or so hadn’t played out in a particular manner at particular times- if, to take just one obvious instance, the dinosaurs hadn’t been wiped out by a meteor when they were- you might well be six inches long, with whiskers and a tail, and reading this in a burrow.” From *A Short History of Nearly Everything by Bill Bryson.