It might be a very different world. Poems and song have been used for millennia to pass stories and history. They've become a part of who and what we are. Whether it's tribal drums or a radio at a tailgate party, music has punctuated our lives and provided soundtrack for key events on historic and very personal levels. Not sure I'd want to even speculate what effect that butterfly's wings would have on humanity if it were to ripple all the way back to the first bloke to tap his foot in rhythm.