evidence: The tale of how humans became such avid carnivores begins 65 million years ago. The dinosaurs have just gone extinct, together with over half of Earth’s species. In rainforests that carpet vast areas of the planet, among soaring trees ribboned with vines, our next ancestor has just evolved. It’s the first primate ever known: Purgatorius. It doesn’t look much like you or me, or even like a chimp. It resembles a cross between a mouse and a squirrel. And if it were still alive today, it would likely pass for a cute pet.