How does the fear of the unknown influence the system of rules and order in Lord of the Flies? What happens when it disintegrates?

A major theme of Lord of the Flies is the fear of the unknown. This group of boys, thrust onto unfamiliar land without any adults or much hope for rescue, must attempt to survive without having any idea of what lays before them. They cannot even fathom what the future could look like. Will they live on this island forever? What will it take to survive on it for an undetermined amount of time?
At first, this fear allows them to come together and live with a sense of order manufactured by the boys with leadership skills. They feel they must stay together to eat, to find shelter, and primarily to avoid the beast.
The beast is not a tangible thing; rather, it’s an idea of all the things they don’t know. As some of the boys become comfortable with the idea that they are alone now and in charge of their lives, their fear begins to disintegrate and with it, all sense of order. Chaos ensues, and though Ralph attempts to reign things in, he is unsuccessful, and ultimately Piggy is killed.