Before you yell at me, yes I am doing another post about the history of an assorted piece of grammar’s immeasurable arsenal. What can I say? I’m a Grammar Nazi, and this stuff interest me. But that’s besides the point. This time, I won’t be covering the history of contractions (which you can read here, if you so wish), but question marks instead. The question mark is a universally recognised symbol, and yet its origins remain quite mysterious indeed. And these two sets of origin stories are as different as stories can get, but I’ll try and do my best to cover both.
The Urban Legend
Of course, there is a nice old urban myth that could be constituted as a thrid origin story, but the likelihood of it being true is slim to none. Some claim that the question mark was actually created as a device to mark places on maps and such that were unknown, and they got the shape from the shape of a cat’s tail that the cat makes when it is inquisitive. They also go on to state that the exclamation point comes from the shape a cat’s tail makes when they are surprised. These two marks reportedly come from the Egyptians, who worshiped cats. However, no punctuation was used by the Egyptians ever, and it wasn’t until the 19th century that punctuation became standardised, so we can safely throw this hypothesis away. Now, on to the other two!
The Romans!
The first (and admittedly the less likely) of the two stories starts where most things inevitably start: in Rome. The story goes that the question mark actually originated from the Latin word qvaestio, meaning question. This word was reportedly abbreviated in the Middle Ages by scholars as just qo. Eventually, a capital “Q” was written over the “o”, and it formed one letter. Then, it morphed into the modern question mark we know today. Here’s a picture so you can visualize it. 
However, the actual evidence that this is the case is almost non-existant, for no medieval manuscript found thus-far supports this idea. In fact, it seems that the opposite holds true; the question mark morphs to look more like a q rather than less like a q as time passes.
Alcuin of York
The more accepted story by linguists is that of Alcuin of York and his “lighting flash” of a symbol. Alcuin himself was a scholar living in 8th century England when he received an invitation from Charlemange to join his court. Without hesitation, Alcuin accepted and made his way to France. Whilst in France, Alcuin wrote a myriad of books and poems. Around this time, the need for punctuation in writing was becoming more and more evident, for books were now not only spoken aloud but read silently by monks on their lonesome. Without knowing where to pause or stop, it was a bit hard for monks to enjoy their reading. While there was an old system pioneered by, you guessed it, the Romans in place using a bunch of dots, it wasn’t sufficient. To combat this, Alcuin created the punctus interrogativus to signal an inflection at the end of a clause. The symbol itself was a tilde over one of the old Roman dots. 
Here’s a picture to held you visualise. This “decoration” over the dot remained in constant use up until the 13th century at the end of all clauses, when scholars in Paris decided to standerdise punctuation. They chose Alcuin’s punctus interrogativus to embody solely the interrogative. By that time, the “lightning flash” had been turned upwards, and one could easily recognise it as the modern question mark. By the 17th century, when printing came around, the question mark was used as a universal symbol around the Western world. When the Arab world discovered it, they flipped it to match with their right to left writing style. Eventually, most languages picked up the question mark and used it as their own. At the turn of the 21st century, the question mark is a sort of international super-star, being used by billions of people every day. And that is the history of that little mark at the end of sentences that happen to be questions.
