According to the newest Watchtower:
Jehovah communicated with Adam in the garden of Eden, using human language. God likely did so in an ancient form of Hebrew.
Why are they so stupid?? The bible doesn't even make this claim!
As far as I can figure, the oldest fragment of proto-Hebrew dates form 1000BC. There are many forms of non-Hebrew mark-making and language that date much farther back than that!