In chapter 7, the boys are in the woods when a wild boar runs by them. Ralph takes aim at the boar with his wooden stick, but he doesn't manage to injure the animal. When Jack arrives on the scene, Ralph nearly pleads with Jack to believe that he'd hit the pig. Jack doesn't say much, and Ralph finds that he feels "the [need] of witnesses." This reflects a growing discord in the power structure on the island. Early on, the boys would have believed their leader; now, Ralph begs for someone to believe in him. In particular, he wants Jack to believe that he's hit the pig, symbolizing Jack's growing power within the group's social structure.
Soon thereafter, the group circles around Robert, pretending that he's their pig. As the chants of the group rise and they begin to squeeze him, the group actually begins to hurt Robert, who screams in real pain. Even Ralph "desire[s] to squeeze and hurt" Robert. This pretend hunt demonstrates the degeneration in their social structure and sense of order. They are quickly losing their sense of humanity and are moving increasingly toward savage behavior.
Near the end of this chapter, the group decides to again look for the beast on the mountain. One by one, boys drop out of this journey, until only Roger, Jack, and Ralph remain. Importantly, as they turn the shoulder of the mountain, Jack and Ralph lead jointly, with Roger lagging behind. This represents the dual nature of the leadership on the island. Though Ralph wants to believe that he is firmly in charge, Jack has risen as a supported leader of a subset of the boys—the hunters.