Yeah, but rap evolved from R&B.

I may have written a thread on rock somewhere but I can't remember where I put it.

Cardboard layed it out pretty accurately though.

which is why i picked prog

ooh i can

rock-mineral matter of variable composition, consolidated or unconsolidated, assembled in masses or considerable quantities in nature, as by the action of heat or water.

True, yet oddly enough Prog is still accepted as being a kind of Rock (hence "prog rock"), even though it shares more in common with Classical and Jazz, but it did envolve from Psychedelic Rock which (in part) evolved from R&B, so that might be the reason.

If you can indirectly trace it back to Chuck Berry, it's probably rock.

Probably can't do that with Prog... The Prog band that has come the closest to Rock N Roll is Hawkwind.

Maybe not directly, but if you trace their influences I'm sure the ones that aren't Stravinsky or Coltrane were probably influenced somewhere along the lines by first wave rock n' roll.

A lot of prog bands, for instance, would claim The Beatles or Zappa as influences, and I'm sure both of them were influenced by Chuck Berry.

Good point.

Didn't think about The Beatles, but Yes, KC, Genesis and many others have listed them as influences so they count I suppose.

But I dunno, everyone influenced by Chuck Berry probably shouldn't qualify as Rock, because I believe there are Reggae and Country musicians who are influenced by him, and by similar logic, if being influenced by John Coltrane makes you Jazz, The Doors would be Jazz.