Based on the way the boys are behaving to one another, what conculsions can you draw about how the island is changing the relationship between them?

One of the key concerns of Lord of the Flies is the role of the individual in society. Many of the problems on the island-the extinguishing of the signal fire, the lack of shelters, the mass abandonment of Ralph's camp, and the murder of Piggy-stem from the boys' implicit commitment to a principle of self-interest over the principle of community. That is, the boys would rather fulfill their individual desires than cooperate as a coherent society, which would require that each one act for the good of the group. Accordingly, the principles of individualism and community are symbolized by Jack and Ralph, respectively. Jack wants to "have fun" on the island and satisfy his bloodlust, while Ralph wants to secure the group's rescue, a goal they can achieve only by cooperating. Yet, while Ralph's vision is the most reasonable, it requires work and sacrifice on the part of the other boys, so they quickly shirk their societal duties in favor of fulfilling their individual desires. The shelters do not get built because the boys would rather play; the signal fire is extinguished when Jack's hunters fail to tend to it on schedule.

The boys' self-interestedness culminates, of course, when they decide to join Jack's tribe, a society without communal values whose appeal is that Jack will offer them total freedom. The popularity of his tribe reflects the enormous appeal of a society based on individual freedom and self-interest, but as the reader soon learns, the freedom Jack offers his tribe is illusory. Jack implements punitive and irrational rules and restricts his boys' behavior far more than Ralph did. Golding thus suggests not only that some level of communal system is superior to one based on pure self-interest, but also that pure individual freedom is an impossible value to sustain within a group dynamic, which will always tend towards societal organization. The difficult question, of course, is what individuals are willing to give up to gain the benefits of being in the group.

THere is a sense of oppression developing. Jack is changing the dynamic of some sort of working society to fear and chaos. Jack needs these conditions to take complete control. By opposing Ralph and making him look week, Jack is slowly setting the stage for his dictatorship.

That goes a bit beyond Chapter 4, but this theme permeates the novel from start to finish. Gradesaver's study guide is a fantastic place to get details for each chapter.