[Snerfling]

I agree with your hypothesis, but disagree with your timing. Many different kinds of birds and other wild animals willingly intoxicate themselves on all manner of things.

Ancient man was probably getting buzzed over 3m years ago. He's always liked the feeling. It just took around 2.95m years before he got to the point of identifying and controlling the source.

[Chode]

Yes... that's why I said it took him awhile to connect the dots between the grain being wet/fermented and the buzzz, how long it took is the question.