Andy, I'm not talking today's R&B either!
Rock n Roll - wasn't this more a white hijack of rocking blues?
R&B progressed into Boogaloo which then progressed into Funk. Not necessarily song, more rhythm led music for the dancefloor, based on primitive, sexual musical patterns. Would you not say that Do-wop followed by soul music - took their own path, with the roots in melody rather than rhythm (I know that this is a generalization with so many crossovers). Perhaps that's how it took of in Europe, where melody, traditionally, is generally favoured over rhythm.