Good question

Somebody asked on Reddit: Water is the base drink. What’s the base food?

Evocative question. My instant answer was barley. Barley grows everywhere, unlike rice and wheat and corn. Most of the answers were broader, including all of those localized grains when turned into some kind of bread.

BUT: What about the premise? For most of history, in most of the world, “pure” water was unhealthy. When bread was the default solid food, beer was the default liquid. Also mainly from barley.

The common factor in both is yeast, so yeast should be the default nutrient. I claim that fermentation also gave rise to cooking, so yeast is the base of all civilization.