The lovely Maud points to this New Yorker article by Jim Holt on the history of jokes. Of particular interest to me was the way in which humorous tales, like other literary offerings, are transmitted from one culture to another, undergoing various changes in the process.
The Philogelos was misplaced during the Dark Ages, and with it, seemingly, the art of the joke. Sophisticated humor was kept alive in the Arab world, where the more leisurely folktale was cultivated. During the centuries of Arab conquest, folktales from the Levant, many of them satirical or erotic, made their way through Spain and Italy. An Arab tale about a wife who is pleasured by her lover while her duped husband watches uncomprehendingly from a tree, for instance, is one of several that later show up in Boccaccio’s ‘Decameron.’ Once in Europe, the folktale began to cleave in two. On the one hand, with the invention of printing and the rise of literacy, it grew longer, filling out into the chivalric romance and, ultimately, the novel. On the other hand, as the pace of urban life quickened, it got shorter in its oral form, shedding details and growing more formulaic as it condensed into the humorous anecdote. It was in the early Renaissance that the art of the joke was reborn, and the midwife was a man called Poggio.
The article cites many other examples like this one and is a, er, fun read.