Did you know?
The historical origins of the question mark is (pardon the pun) a bit of a question mark.
One theory says that scholars in the Middle Ages would write the Latin word quaestio at the end of a sentence to show it was a question. Since this was rather cumbersome to write out each time, it was eventually abbreviated. First to qo, then to q on top of o, and finally into the "?" symbol we know today. This is much like how our own cursive signature, which we once perfected in third grade, eventually morphed into the squiggly lines we now use as adults. But alas, there is little evidence to back up this theory.
A competing theory, also unsubstantiated, argues that the curve of the question mark traces back to the ancient Egyptians. Since Egyptians were famed for their worship of cats, it makes sense they would have been inspired by the similar shape of an inquisitive cat's tail.
In the end, perhaps it's appropriate this question remains a mystery. What do you think?