It's not the first hip-hop archaeological dig (see Yazoo's The Roots of Rap, for one). But this mix of proto-rap testifying, trash-talking and gibberish from the Twenties to the Sixties may be the most far-ranging one yet. Often it's more about spirit than sound. The 1952 novelty "Hambone" combines nursery rhymes with thigh slaps and cheek pops that would impress Biz Markie, and when Joe Hill Louis hollers, "We'll all gotta go to jail," on the raw, rabble-rousing 1950 blues "Gotta Let You Go," dude's utterly gangsta. And even when connections seem stretched, the liner notes make the logic amusing: Any set trying to link the Rev. J.M. Gates with N.W.A and Harmonica Frank Floyd with Kid Rock is definitely history worth hearing.