I have written some pointers about the history of Greek punctuation on my Greek Unicode Issues website: Punctuation.
- The basics of punctuation as we know it in both Latin in Greek were in place by around the 10th century, including commas, periods, and interrogatives. They appear to have developed independently, although they had common antecedents in Roman era punctuation, as pioneered in Alexandria.
- The high dot was Alexandrian, and ended up with the function of the semicolon in Latin.
- The Greek question mark developed at the same time as the Latin interrogative, but it looked like the Latin semicolon, and has not changed.
- The high dot also performed the function of the Latin colon. Typesetting of Ancient Greek still often uses the high dot in that function. Modern Greek now uses the colon instead.
- The other shared punctuation—exclamation mark, parentheses, dashes, ellipses, quotation marks—are Renaissance innovations, introduced into Greek from Latin script.
- Different countries punctuate Ancient Greek following their local norms—e.g. use of quotation marks, propensity to ellipses and exclamation marks, etc. The Modern Greek preferences in punctuation are French: use of guillemets, use of quotation dashes, etc. Greek also used expanded typing (Sperrdruck) from German instead of italics, although that is now out of fashion.