> In the case of grains, it doesn't become food until you harvest
> it, thresh it, and process it.  I think this wouldn't make much
> sense to people worried about running out of food here and now.

It would make sense to plant, move on, and return to harvest. A pattern
of settled agriculture could easily follow, if the people were open to
change. No doubt some early adopters started it, perhaps by staying
behind to guard the crop.

Bill