Elsewhere....I just had the conversation yesterday with someone. LOL
Talesin...remember back "in the day" sanitation for human waste was also a bit suspect. Hence shellfish posed an even greater risk than it does today. Not just red tide, but E coli and other very common bacterial contamination if human / animal waste gets into the local water.
Why does any religion pick and choose? Wearing a shirt made of two threads....that's ok. Shellfish is ok. Pork.....bad? Homosexuality? Bad? Leviticus was a book of clean rules.
Can you imagine asking all women who are in their "time of the month" to walk around the city yelling out "Unclean.....unclean" like the bible commanded? LOL