Cir cumcision was a widely practiced custom in many socities around the world, not just among the Jews and Muslims. Regardless of the reason (I suspect that, ultimately, hygiene is a big part), it is long establisahed by custom and not by decree of God or gods.
As for diretary laws, those exist elsewhere, as well, without obvious Divine imposition. Eating of pig is not only against Kosher laws and Halal, but was proscribed by the ancient Egyptians and the ancient Sumerians.
Yet in Polynesian societies, eating of [pig is not only allowed, in some places it’s practically a religious duty. It must surely be a coincidence that on many of these islands the pig is the only large land meat animal. This sort of thing again suggests some practical reason for the ban in the Middle East. As I’ve mentioned before on this Board, cultural anthropologist Marvin Harris suggests that many foodways – especialy the kosher laws – are the result of practical considerations.(Not all of the, though). His book Good to Eat (AKA The Sacred Cow and the Abominable Pif) is entirely devoted to such things, although he discusses the ideas in his other popular books, too.
Put bluntly, he doesn’t blame trichinosis, but the cost/benefit of raising pigs in a location where most of the food they can eat is in direct competition with human food (Pigs don’t eat grass and other leafy plants, as cows, sheep, and goats do – they eat tubers and roots and nuts, which people do), so it makes more sense to eat the food you’d feed the pigs and cut out theinefficiency loss you incur by dfeeding the pigs. In addition, pigs overheat easily in desert climates – they don’t sweat. They require water-filled (or mud-filled) wallows to keep cool, and if they don’t get them, they will use their own urine and feces – NOT because they’re filthy animals, but because without some such means of regulating body temperature, they’ll die. But the practice certainly isn’t good for the pigs’ reputation. Pigs also can catch and transmit a lot of the same diseases people have, so raising them in tough conditions can be hazardous.
On the other hand, if you can let your pigs run wild in a place where they can dig their own roots and wallows are plentiful (or can hunt wild swine, like boars, that do this already), then pigs are a boon – they reproduce at a phenomal pace and put on weight rapidly, and have a large percentage of edible meat. Queen Isabella pressured Columbus to bring pigs to the New World, where they immediately became a prime food source(and may have helped infect the native population with European diseases). American farmers found the combination of pigs and corn a perfect way to get food to market in the 18th and 19th century, as Harris documents. But in the Americas, as in Polynesia, the pigs could find a lot of their own fare, and didn’t need constant tending. You COULD raise pigs in the Holy Land – the story of the Gadarene swine shows that SOME people did. But, goes the theory, people who didn’t had fewer problems. Pig was an extravagant luxury there.