Walter Bright wrote:
Even writing has its problems. What are you going to write on? Bark? Animal hides? How are you going to make paper? Ink? A hunter-gatherer tribe may find it not worth the effort, and so the writing will not "take".
The Maya wrote on treated Birch Bark, which apparently worked great until Spanish Missionaries burned all their libraries :-) Sumerians used fired clay tablets for writing, and treated animal hides were pretty popular until relatively recently (Vellum, for instance). Vegetable dyes would make decent ink, if needed.
The bigger problem with writing is the difficulty in transporting the books or whatever, assuming a hunter-gatherer culture. Until agriculture, I can't writing being used much outside of "graffiti" on cave walls, trees, etc. From your date of 20,000 BC, I believe you predate agriculture by at least a few thousand years (I recall hearing speculation about Human settlements in the teens somewhere).
