Rules of Society in the book Pearl by John Steinback

I have to write an essay for my english class about rules of society in these four books: Lord of the Flies, Summer of My German Soldier, When the Legends Die, and Pearl. I understand the rules of society in three of those books, but i can't figure out what they are in the Pearl. Can someone please help me? Thanks.

Think not about the rules of the society of pearl divers and others of their social class, but of the wider society in which this class exists. What are the rules of that society? How do those rules shape the lives of the protagonist and his family?