History of Beer

"Beer is one of the oldest beverages humans have produced, dating back to at least the 5th millennium BC -- prior even to writing -- and recorded in the written history of Ancient Egypt and Mesopotamia." - Wikipedia

It is speculated that the first beer was brewed from barley or malt.
Someone left a basket of barley out in the rain which eventually started to ferment.

Wikipedia has an excellent article about the history of beer here