Answer: The island setting forces the boys to adapt to the wildness of their environment by letting go of some of society's conventions.
When the children arrive to the island, they need to let go of some of society's conventions, as many of the rules that society depends on will not help them ensure their survival. Moreover, as they are children, their morality is not as clearly defined as that of adults (while at the same time, they are also more innocent and less corrupted). However, as the book progresses, the children need to let go of more and more conventions, until almost all trace of civilization is gone from them.
