ABSTRACT
Humankind is omnivorous and obtains its food either directly from plants or indirectly from them by consuming a variety of products such as meat, poultry, eggs, fish, milk, and their products made by animals that derive their sustenance from plants. In this sense, all flesh is grass, and the sun is the ultimate source of all food energy. Thus, efficiency of food production is closely linked to the proximity of our foods to the source of solar energy. The efficiency of conversion of sun’s energy into the chemical energy stored by plants in the form of carbohydrates, fats, and proteins is around 1% or 2%. Each time this energy is transferred to another organism, significant loss in energy occurs. The flow of energy through a succession of living organisms (a food chain or web: plants-animals-humans) means that the further a person’s diet gets away from plants, the higher will be the cost of food. Therefore, when food gets scarce humans must be a direct rather than an indirect consumer of plants.
