So punctuation is a type of musical notation for high-level meter and pitch, while the words are like the lower-level rhythm. Pitch and meter fluctuations, over the ranges of phrases and sentences, are what many spoken languages use to chunk sentences and phrases, which helps listeners disambiguate the connective structure of the words.<p>Quite interesting that punctuation co-evolved with musical notations. I had thought that punctuation existed prior to musical notation.<p>Side note: although American English speakers employ quite diverse pitch and meter patterns, e.g. more homogenous populations, as in many European countries, have extremely consistent spoken pitch and meter usage patterns over phrases and sentences.