I thought it was because of the tapeworms. All for sound health reasons (at that time). Same with a whole lot of other Jewish (don't know if they apply to Muslims as well) no-no's - like shellfish, often dodgy (especially in summer - hence the saying about not eating oysters when there isn't an R in the month) because, I think, the way they feed makes them likely to pick up bacteria from sewage, and ritual washing before eating and using separate plates for stuff - note how in restaurants today they have to use different chopping boards for veg & meat - same thing - it all makes sound hygiene sense!

Someone who knew an awful lot about disease and hygiene, which Europeans didn't discover till the 19th century, to lay down all these "rules" ... but we've had all the does God exist arguments already (on the Here our Prayer thread). Personally, I'd go for the time travel/aliens theories .... (I've read too much science fiction!)