That review suggests reading Paul Saenger’s book on spaces between words together with Malcolm Parkes, Pause and Effect. An Introduction to the History of Punctuation in the West (1993). I managed to find a review of that on the Internet too. Among other things, the book discusses the importance of marking up text for intonation – this is the value of the inverted question mark used in Spanish, introduced by the Royal Spanish Academy in the 18th century.
I am very taken with the word punct, the precursor of the full stop (U.S. period) originally used to separate words. The OED has it, with a number of meanings, all obsolete.