Hieroglyphics

It dawned on me today that hieroglyphs may be nothing more than the result of boredom.

Take your average cave man.  He's in a cave with his fellow cavies.  They're holding a meeting to discuss which end of a carcass they should begin gutting once they've gotten one.  One dude off in the back has a sharp rock and next thing you know he's yawning, trying to keep his eyes open.  Doodling commences and a thousand years later we're sitting here trying to figure out why we can't figure it out.

How do you explain the glyphs on the sides of tall rocks?  Managerial offsite with lunch provided!

~w