God I read this so long ago but assuming Bob is the guy accused of beating the white guy's wife, I think the book lets the reader know that he's left handed through Atticus's demonstration when Atticus threw something at Ewell and he caught it with his left hand. Atticus then asks why he didn't catch it with his right and then Ewell says he hurt it when he was younger.
she was going to move away???
It's the last one. we know this because it talks about how even with the smart hands of a scientist, the plan is not completely foolproof, or safe
I believe the answer would be ignorance. Many of the cultures were actually very aware of their surroundings, and the world they lived in. Mostly through this interest, ancient cultures were currently finding out new ideas about their world.