Why do all languages share the same intonation for questions?
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?
As I checked from an article, at least in Mandarin the usage of particles happens alongside the change in intonation, not at the expense of it.
Also note that even [some? all?] Germanic languages show something similar - but instead of a particle, you get a syntactical movement (verb fronting) overtly marking the question. Examples:
English
German
This is an apple.
Das ist ein Apfel.
Is this an apple?
Ist das ein Apfel?
The cat meows.
Die Katze miaut.
Does the cat meow?
Miaut die Katze?
In English this is slightly obscured by do-support being obligatory for most verbs, but note how it's the same process - if you were to insert the "do" without a question, in the third sentence, it would end as "the cat does meow".