The task of getting enough food has been with man and his animal ancestors ever since the beginning of life, and it still remains the major task of humanity even in this scientific age. Three-quarters of the people in the world today are occupied in agriculture, and most of them depend on the produce they raise themselves. This has been the pattern of life ever since the agricultural revolution, some six thousand years ago. The old basic pattern of peasant subsistence farming is still the predominant one, as far as numbers are concerned. However, in a few, but highly productive, parts of the world it has been replaced by another in which the actual food-raising is largely separated from the food consumption, where highly mechanized farming, using a very small number of people to the acre, provides food for many times that number situated in distant cities (Fig. 6, p. 183).