I could be wrong here, but it seems to me that a common aspect amongst all languages is the tendency to raise the pitch of your voice slightly when asking a question. Especially at the end of a question sentence.
If I’m wrong about this raised pitch being common amongst all languages, at the very least do all languages change their tone slightly to indicate that a question is being asked?
I guess there needs to be some way to indicate what is and isn’t a question. Perhaps a higher pitched voice reflects uncertainty. Is this something deep rooted in humans, or just an arbitrary choice when language developed?
“Rhetorical” questions - like this one - are specially interesting because, while they follow the syntax of a genuine question, they’re pragmatically assertions. You’re implying “this is not true”, even if you’re phrasing it as a question.
And that phrasal pitch contour that you see in yes/no questions is dictated by the pragmatical purpose of the utterance, so if the “question” is not actually a question, it doesn’t get it.