"Food is any substance that can be metabolized by an organism to give energy and build tissue. Foods are made up of a combination of calories, proteins, fats, minerals, and carbohydrates. Enzymes in the mouth begin to break down sugars as food is processed for digestion. Upon entering the stomach, the acids therein separate the nutrients and useable compounds in the food in the processes of digestion. These are then absorbed into the body to become the energy source for functioning at the cellular level.
The importance of obtaining and processing food in order to live has been a driving force behind human evolution and culture history. It is hypothesized that the quest for food in the shrinking forests of Africa played a role in bipedal adaptation. Furthermore, the subsistence patterns of different cultural groups influence many of the other institutions in that society...."
Fernandes, Luci. "Food." Encyclopedia of Anthropology. Thousand Oaks: Sage Publications, 2005. Credo Reference. Web. 28 Apr 2015.