S O'P: "I have a notion that the narrative morphology of folk song & folk tale is hard-wired into the human brain as an essential aspect of our preparedness for the structures of language itself."

I think that's an interesting suggstion. Lewis-William and Pearce's book,'Inside the Neolithic Mind' makes a similar point for the origin of religious experience and practice. I'm not sure about the 'hard-wired' as I worry about computer analogies when speaking about the humand mind, consciousness etc. I think I might prefer Sheldrake's idea of morphic resonance - but that's an entirely different issue. The concept that similar forms, varieties, ideas and so forth can occur simultaneously across the country - or the world - is one that has never occured to me before with regard to music, whether you call it 'folk' or something else. Nice thought and, for once, some original thinking on the subject!