Capital letters (Part 1/2)

Well, again, sorely neglected research dump spot. Pas bien. Ah well. Recently been prompted as to CAPITAL LETTERS.

So! Let us brainstorm –

Why do we have capitals now?

Where did capital letters come from?

PPuncpWas there a runic equivalent?

Why/why not?

Evidence: Earliest documentation I can find of capitals being used in early English.

Does Tolkien use capitals in any of his scripts? (Because why reinvent the wheel when a master linguist has done heavy research on it.)

Is it necessary to have my own interpretation of capitals?

Part 2