In one sense, human heads function much like those of other mammals. We use them to chew, smell, swallow, think, hear, and so on. But, in other respects, the human head is quite unusual. Unlike other animals, even our great ape cousins, our heads are short and wide, very big brained, snoutless, largely furless, and perched on a short, nearly vertical neck. Daniel E. Lieberman sets out to explain how the human head works, and why our heads...