A ban on pork was included in the old Jewish laws for the same reason as mandatory circumsicion: to increase the tribe's numbers. Whereas circumcision increases fertility (before they had fertility drugs, at least), avoiding pork was a measure to prevent disease. The Christians never adopted this law, because pork was always a very important part of the diet in European countries. Also "pork" in the Middle East was a different thing than "pork" in Europe. In Europe, pork refers to meat from pigs, which are relatively clean. Whereas, in the middle east pork would refer to hogs, that tend to eat garbage and such.