Read this article on Neatorama to find out how some of our punctuation symbols came to be.
Question Mark
Origin: When early scholars wrote in Latin, they would place the word questio – meaning “question” – at the end of a sentence to indicate a query. To conserve valuable space, writing it was soon shortened to qo, which caused another problem – readers might mistake it for the ending of a word. So they squashed the letters into a symbol: a lowercased q on top of an o. Over time the o shrank to a dot and the q to a squiggle, giving us our current question mark.