Nell Irvin Painter’s title, “The History of White People,” is a provocation in several ways: it’s monumental in sweep, and its absurd grandiosity should call to mind the fact that writing a “History of Black People” might seem perfectly reasonable to white people. But the title is literally accurate, because the book traces characterizations of the lighter-skinned people we call white today, starting with the ancient Scythians. For those who have not yet registered how much these characterizations have changed, let me assure you that sensory observation was not the basis of racial nomenclature.