A Better Theory: In Defense of Food by Michael Pollan

My first guess was that it was like lactation. When the mother stops nursing, she stops lactating. Similarly, I guessed, when the child stops nursing he stops producing lactase.But there does seem to be a genetic basis, which is not surprising. Fairly simple chemical events can become "enshrined" in genetics quite easily - as opposed to complex events such as a group of people "deciding" to consume milk from other species.

Soaking and fermenting would be one of the simplest forms of processing, suitable for use in cultures with simple technology. Sprouting of seeds is also good for the nutrient content as I understand it.Another simple method, crushing and grinding, is prone to having the wind blow away the lighter constituents. That may have given our ancestors the idea of throwing away the less palatable bits.

I have made beer in the past so I have some familiarity with this process. When you put barley in warm water and let it germinate you get the expression of enzymes that change starch into simple sugars that are needed by the developing plant. This process is called malting. For the purposes of brewing beer, the malted barley is put into an oast which removes water from the germinating seeds and freezes barley in this active state. When you are ready to make beer/whiskey you crush crush the barley (grist) and put it into hot water (mash). This puts the enzymes into high gear and turns a lot of the starch into simple sugars which are washed out of the barley grains (sparge) and used in the process of fermentation.The whole process allows you to extract more digestable sugars, and the fermentation is really just spoiling the food so that the end product is edible. Before refrigeration, spoilage was a way of life so people figured out how to use the process of spoilage to their advantage.