In the past due to war, weather problems, and disease there were a series of "great famines". These were not the usual winter shortages, they killed a lot of the population. One factor was the so called little ice age and the need to change to new crops. Here is a you tube that describes some of the survival food that they came up with and that are still important alternatives if the food delivery system fails. And here are some of the foods we ate during the depression in order to survive.
