What is it that makes us entertain fantasies about mating outside our own species? Surely this can’t be in our DNA; the mule, sterile offspring of a horse and donkey’s mating, is an example of the evolutionary dead end that results.Yet since our earliest days we’ve apparently been fascinated by the non-human cultures we co-exist with, and the fantasy of strange creatures, able to shift from wild animal to human. Long before we could write, we told stories around the campfire about them, as lovers, not monsters.