There's something about the idea of munching on a nice leg o' man that makes everyone want to be a comedian.We use jokes to hide anxiety about touchy subjects, of course, but it's more than nervous laughter. People like to discuss eating people--once someone else brings up the subject. William Bueller Seabrook, a man who acquired more firsthand knowledge about the fundamental facts of cannibalism than most of the civilized people who talk about it,...