Legend has it (it may even be true) that J. B. S. Haldane, when asked by a clergyman what he could infer about God from the works of creation, responded, "He must have had an inordinate fondness for beetles." Were I asked to infer something essential about Homo sapiens from his work, I should probably reply that this zoological odd-ball required humor to lighten a life taken too seriously. How else can we explain the fact that very profession has...