There is an animal roaming the savannahs of sub-Saharan Africa that has confused, fascinated, and at times horrified naturalists for centuries. The spotted hyena — Crocuta crocuta — looks, at first glance, like a rough-edged cousin of the dog. But look more carefully and you are looking at one of the most biologically unusual creatures on earth, and one whose story raises genuinely interesting questions about what female biology is capable of, and what it reveals about our own.