In 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 changes in diet were created, primarily through religious principles. However, aside from the religious aspect, there are underlying causes for these dietary restrictions. Marvin Harris and Mary Douglas both propose some of the underlying causes of dietary restrictions in ancient texts. Harris offers several reasons for dietary restrictions in Leviticus, including moral, ethical, and functional, while Douglas presents the cost-benefit and historical reasons for dietary restrictions in several religious texts. Harris' approach is the cost-benefit analysis of breeding certain types of animals. . He claims that it is more efficient for humans to eat plants since there is less energy loss in the food chain. It was better to eat plants than to feed plants to animals for meat. By consuming animal flesh, humans receive only 0.02% of the original sunlight captured by photosynthesis. Additionally, raising cattle or domestic animals creates pressure on ecosystems and pressure on reproduction, forcing people to choose between crops and livestock. These factors are essential in developing countries, especially in ancient times. Despite the pressure created by raising domestic animals, they had many benefits beyond the value of meat. Domestic animals were used as traction machines, producers of fiber, fertilizer, producers of wool, skins, milk. 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 ...before ungodly and received no blessing from God, granted only through the care of the 'man. Only wild animals with cloven hooves and ruminants were considered clean, this is the first factor defining clean animals, the second is the use of the animals and their value, like pigs which have no value since they only produce meat and do not chew the cud, the third determining factor is the reality in which the animals live. In the air, only two-legged flying birds are clean. In the country, only four legs jump or walk. In the water, only those who swim with fins and scales are clean. Predatory habits or scavenging were not taken into account. The dietary rules explored by Douglas were restrictions with the aim of inspiring meditation, on the purity and completeness of GodWorks. Cited Harris, Marvin. Cannibals and kings. New York: Vintage Books, 1977. Print.