This is a startelingly familiar argument to me. Many arguments like this have happened in paleontology. If I may be so bold, I'd like to offer a few insights from my field's experience:
1) Don't confuse answering "What benefit does this have?" with "Why did this occur?" Often benefits are only realized after something occurs; the actual reason for the occurance can be something else entirely, even something detrimental. For example, even if tapeworms were known to come from pig meat, it may be that the ancient Jews forbad eating pigs for some other reason entirely, such as a disease that wiped out all their pigs (removing them from their diet). Or it could be that pigs were an accidental victim of a ban intended to hit some other animal entirely. And we ARE dealing with religion here; looking for answers that make sense to a secular mind isn't the best way to go about it. The question is, what was the reason for banning various animals? While benefits may be helpful in finding the answer, they are not answers themselves.
Which brings me to my second point....
2) Go to the source. The only way to answer this effecitvely is to go to the archaeological record of the time when Jews banned certain animals from their diets and see what was going on. Modern knowledge is quite irrelevant; you have to look at this from the perspective of the Jews at that time. Who were they fighting? Who were they allied with? What were the economic forces? What was their religion like? Otherwise, you end up very quickly answering the quite irrelevant question of "Why would *I* ban eating pork?" (I'm not trying to insult anyone here; we ALL fall into that trap if we're not careful, it's a function of human cognition).
JabbaPapa said:
... but the "illiterate iron age goatherds" had no ability to observe a correlation between pigs, tapeworm, and pork ?
Double standards.
The fact that one has a tool in no way implies that one uses it consistantly or accurately. It's no double-standard; it merely means that they did something different that time. Humans aren't simple creatures, which is one reason I stuck with paleontology. The problem is made even worse when dealing with what we now consider medicine, because that was entirely in the realm of mysticism at the time, and thus it's easily possible for the peoples of the time to apply criteria that are completely alien to our own understanding of how things work. The Enlightenment included men very well-versed in physics and causal relationships, yet bleeding of patients was still a very common medical procedure due to the medical paradigm. A similar paradigm difference between us and ancient Jews could render thier concept of causal relationships in regard to tapeworms nearly unintelligeable to us (no insult to them; it's an issue of discussion between paradigms, not one being smarter or stupider than the other).
