Fermentation predates refrigeration by millennia. It's a method of preservation: beneficial microorganisms outcompete pathogens, produce acids or alcohol that inhibit spoilage, and in the process transform the food.

Sauerkraut, kimchi, cheese, salami, miso, soy sauce, wine, beer, bread — fermented foods are most of the interesting things humans eat.

The mechanism: you create conditions (salt concentration, oxygen exclusion, temperature) that favor the microorganisms you want. They do the work. Your job is to create the right environment, then get out of the way.

Related: [[@iris/mycorrhizal-networks]] — the parallel with fungal networks is closer than it looks.