The Dozens: A History of Rap's Mama, by Elijah Wald

Elijah Wald says his inspiration for writing this book was the idea of a link between blues and rap: a stream of African American folklore that fed into popular music at different junctures along the years.  The main supply here is a tradition known as "the dozens."  But what is the dozens?  At it's most specific, it's a formal game where two opponents face off in front of an informal audience trading rhymed insults, usually about their opponents relatives, and especially their opponent's mama.  First one to lose his or her cool and throw a punch loses.  Beyond that, things get a bit difficult.  Does the term also include formal battles that don't use rhymed couplets (apparently much more common)?  Blues or jazz songs that incorporate the insult rhymes?  Informal trash talking between two friends?  What about the tradition known as toasting, the epic off-color rhyme stories like "The Signifying Monkey?"  For that matter, how common are the formal, rhymed battles?  And if they do happen, did they inspire minstrel comedians' routines, or is it the other way around?  Identifying what is and isn't "the dozens" (let's not even get into trying to figure out the difference between "playing the dozens" and "putting someone in the dozens") is...well, exactly as impossible as making a definitive statement about what is or isn't punk rock, or film noir, or cubism.
We know the practice dates back to the early 20th Century, although most scholars believe it dates back to slave days and was likely brought over from Africa (Wald and the researchers he cites are perplexed about why the common West African practice of greeting a friend by saying "Your mother's cunt" didn't make it to the States).  But of course, everything before the early 20th Century is obscured by the clouds of time.  There is no record of it, as nobody really believed African American folklore to be something worth preserving or studying.  And the early accounts of the practice are further obscured by the perspectives and agendas of those recording them.  Wald takes an  inquisitive, scholarly approach to his material, which may seem a bit dry compared to the more sensationalist writing of certain authors I've recently read, but ends up being more satisfying and, ultimately,  interesting.
The dozens feeds into popular entertainment from an early date.  Jellyroll Morton talks about hearing a song in Chicago sometime around 1908 called "The Dirty Dozens."  Played on piano, it's a long song with improvised insult verses and a refrain of "Your mama don't wear no draws."  In  minstrel shows, dozens insults are incorporated into the routines of black (and probably white blackface) comedians, and possibly musical routines.  This serves as a good demonstration of why it's futile to try to distinguish "authentic" folklore from commercial pop: it's entirely possible that, by the time anyone began making any record of the dozens, the practice had already been influenced by the commercial performance version of this art form.  In 1929, Speckled Red recorded a song called "The Dirty Dozen," a bowdlerized version of a song he used to perform at work camp barrellhouses, probably a descendent of the song Jelly Roll Morton had heard.  The original version he had performed live was, of course, unrecordable at the time, but years later he would play it for a field recording session.  But the "clean" version became a hit, and the dozens meshed with the blues forever, just as they would eventually mesh with hip hop.
I'm not going to say much more about the book, but if you want a new take on blues, rap or black comedy, this is a rich book that takes you down some interesting paths.