system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How did humans discover how to make bread?

I'll just put this yeast in with this water and flour and - OH. It just seems like a strange thing for early humans to do and discover all around the world.
gpt
Orginally, bread did not have yeast.  It was simple water/flour paste that was cooked over flame or on a hot stone.  This is "unleavened" bread.  It's still made this way in many countries.  Yeasts were not something you bought...they were (and still are!) yeasts that are floating around in the air all the time.  At one point, some of these natural yeasts would have landed on the water/flour mixture and began to ferment... causing the bread to rise.  The ancient baker probably said  "what the hell...I'll cook it anyway" and basically realized that his new bread was something interesting.   He probably had no idea what happened...but he kept doing the same thing and it kept happening. Or, he kept some of the "new dough" that rose, and added to some new dough... this is called "sour dough" and we still do that.   It was not until fairly recently (1860) when we figured out what, exactly, yeast was.