A culture’s food customs are perhaps more influenced by the physical environment than by any other aspect of culture. But here, too, a people’s beliefs can have a major impact on diet. Pigs, for example, are a good source of protein in many parts of the world, including China, Europe, and the Pacific Islands. In the Middle East, however, both Judaism and Islam regard pigs as unclean and prohibit their consumption. The taboo probably originated in environmental factors: Pigs were expensive to feed and produced no materials for clothing. However, because some people were still tempted to squander resources by raising pigs, the prohibition became culture and was incorporated into both Judaic and Islamic religious texts.