Richard Wrangham, an anthropologist at Harvard, claims that hominids became people—that is, acquired traits like big brains and dainty jaws—by mastering fire. He places this development at about 1.8 million years ago. This is an appealing premise no matter who you are. For those who see cooking as morally, culturally, and socially superior to not cooking, it is scientific validation of a worldview: proof that cooking is literally what makes us human. For the rest of us, it means we have a clever retort the next time one of those annoying raw-food faddists starts going on about how natural it...