Throughout human history, humans have consumed many things, from plants to human flesh. It's all about survival. However, as societies became more complex and states began to form, several dietary changes were made, mostly by religious principles. However, there are causes behind these dietary restrictions beyond the religious aspect. Both Marvin Harris and Mary Douglas propose some of the underlying causes of dietary restrictions found in ancient texts. Harris proposes several reasons for dietary restrictions in Leviticus, including moral, ethical, and functional, while Douglas presents cost-benefit and historical reasons for dietary restrictions in several religious texts. Harris' approach is the cost-benefit analysis of raising certain types of animals. He claims that it is more efficient for humans to eat plants because less energy is lost in the food chain. It was better to eat the plants than to give the plants to animals for meat. By consuming animal meat, humans get only 0.02% of the original sunlight captured by photosynthesis. Raising cattle or domestic animals also creates pressure on ecosystems and reproductive pressure, forcing people to choose between crops or livestock. These factors are critical in developing states, especially in ancient times. Despite the pressure created by raising domesticated animals, they had numerous benefits beyond the value of the meat. Domestic animals were used as traction machines, fiber producers, fertilizer producers, wool producers, leather producers, milk producers. In fact they were more valuable alive for their products than dead for their meat. The value of animal by-products explains why meat had disappeared from the table of some ancient civilians...... middle of paper ......formerly ungodly and received no blessing from God, granted only by the care of man. Only wild animals with cloven hooves and ruminants were considered clean, this is the first factor that defines clean animals, the second is the uses of the animals and their value, such as pigs which have no value since they only produce meat and do not ruminate, the third determining factor is the environment in which the animals live. In the air only two-legged flying birds are clean. In the earth only four legs that jump or walk. Only those who swim with fins and have scales are clean in water. Predatory or scavenger habits were not considered. The dietary rules Douglas explored were restrictions intended to inspire meditation, on the purity and wholeness of GodWorks CitedHarris, Marvin. Cannibals and kings. New York: Vintage Books, 1977. Print.