The present study suggested a simple analytic description of the basic dividing of foods between ruminants and humans when it was based on the production of forages or grain crops, or both. The results obtained were as follows. (1) Humans depended basically on the grain crop and forage production for the raw materials of foods, where harvest index of grain crops and the production ratio between forages and grain crops were essential factors. (2) Forages and straws from grain crops were used as ruminant feeds. (3) Grains and animal protein from ruminants were used for human consumption. The results (1), (2) and (3) supported the human life.