Kosher

[Arpikarhu]

alot of it is the dairy/meat thing. the idea is that you are not supposed to eat the mother at the same time as partaking in the mothers milk. also no animals with cloven hooves and no seafood without fins.

while it is now a religious thing i can only assume it grew from common sense eating ideas.
in the times when these laws were created it made sense no to eat shellfish as the waters were usually polluted with human feces and proper cleaning techniques werent known. same goes for animals with cloven hooves. goats and pigs are garbage eaters and considered unclean.
as for the mother and her milk , this made sense from an animal husbandry view. it stopped people from killing cattle and keeping them for thier milk thereby creating stock .

its all common sense shit that was co-opted by pharisees and made into religious law.