Production of food on a large scale has been carried on for some centuries, but raising food for the use of others to be sold them for gain is not so old. With this has developed food-transportation, storage, commerce. The early search and strife for food and the later producing of it have passed for most of humanity into simply purchasing food.

Food-production for commercial distribution occupies many workers. Food industry that manufactures such foods as flour and sugar, and prepares such as cereals and canned foods of all kinds also engages many workers, as do too, all the processes of handling food not only in transportation but commercially in markets.

Science as it is known to-day has been developed within this century. For not more than fifty years has it been even somewhat generally understood and only now at all popularly known. Eons of life, ages of human development, and centuries of mental effort to understand the workings of nature preceded the scientific enlightenment of this age. Rapid movement is now everywhere made to use in living what is being learned. This is leading to changes that alter human life and affect the ways of living.

The study of food is one of the most recent, also most far-reaching effects of science upon human health. Human growth can be furthered by understanding living. The reproduction of nature's products and effects is more and more attempted artificially and more and more nearly approached, yet the reaction of the human body to artificial foods is not usually the same as to natural. This requires that the difference between the two be further studied and eliminated, or the use of natural foods be continued, if health, vigor, growth are to be promoted by food.