Question mark
In the early 13th century, when the growth of communities of scholars (universities) in Paris and other major cities led to an expansion and streamlining of the book-production trade, punctuation was rationalized by assigning Alcuin's stroke-over-dot specifically to interrogatives; by this time the stroke was more sharply curved and can easily be recognized as the modern question mark.
Quotation mark
The single quotation marks emerged around 1800 as a means of indicating a secondary level of quotation. One could expect that the logic of using the corresponding single mark would be applied everywhere, but it was not. In some languages using the angular quotation marks, the usage of single ones (‹…›) became obsolete, being replaced by double curved ones (“…”); the single ones still survive, for instance, in Switzerland. In Eastern Europe, the curved quotation marks („…“) are used as a secondary level when the angular marks («…») are used as a primary level.