"I wanted to talk about the whole process of how music evolves, and what role music of the past has to do with that evolution."

It's an interesting question Jerry. When you go back to look at early rock and rock, its roots and antecedents (blues, hillbilly music, etc) are really obvious. They become less so over the years, as rock music develops as a genre in its own right. Yet, you can trace the evolution of rock and see how one development/innovation led to the next or came about as a reaction against what came before (e.g, punk developing as a reaction to 70s soft rock and AOR, but with it's roots in 60s garage band music).

I wonder now, though, if rock is in a post-evolutionary phase? Anyone can access its entire history at the click of a mouse, as well as its antecedents, related genres, spin-offs and blind alleys, and create a music that doesn't necessarily naturally follow on from what came before, but takes its cues from a gigantic historic pick and mix. Exciting times, huh?