Beer, an invention specific to each brewing basin?
Dividing the world map into brewing areas does not imply that they are isolates. A "brewery basin" exchanges with its neighbours. But each region is potentially a birthplace of beer. There are about twenty of them in the world (List of Brewing Basins).
We cannot explain the almost simultaneous presence (7th millennium BC) of a primitive brewery on the shores of the Persian Gulf and the China Sea (4000 km as the crow flies)? Or in China and Mexico, with wheat and millet beers on one side and corn beers on the other. These are just two of the most striking examples. No contact between such distant regions can be imagined in ancient times concerning a brewing tradition.
These results invalidate the old diffusionist theory, insofar as it is still necessary to do so. The emergence of beer is an indigenous process. When the brewery moves, it is with the populations that carry with them their fermented beverages, their economy, the social values they assign to their fermented beverages and their drinking manners.
In fact, we have broken up the difficult question of the origins of beer: instead of one chimerical single hub in the world for the primitive beer, we have about twenty! 
 A unique cradle of beer which historians usually located in Mesopotamia or Egypt. From there, beer would have flooded the whole world!