William Golding wrote Lord of the Flies as a response to what he saw happening in the world. He believed that humanity was innately evil. In order to prove this theory, he used the children because they are believed to be innocent. The dynamic between the boys and the island demonstrates the boys' loss of civilization and humanity as they spend more time separated from society.
When the boys initially land on the island, their plane crashes on the beach. Although the wreckage is washed to sea, there is a visible "scar" that remains on the island. This scar is the first symbol of the boys' pollution of the Eden-like setting of the island.
When the boys make their initial rescue fire, the flames burn out of control and destroy a significant portion of the jungle and kill a little'un with the mulberry birthmark. This fire symbolizes the lack of judgment and concern the boys have. They are afraid but their fear quickly subsides when the fire is extinguished. They do not have remorse for the destruction they cause. This is another indicator that the mood on the island is shifting from carefree to dangerous.
After spending some time alone on the island, the little'uns begin to have nightmares about the island. They believe there is a "beastie" on the island. Both Ralph and Simon agree that they little'uns act "as if it wasn't a good island" (72). This is ironic because the island is a symbol of purity and unadulterated nature. The boys contaminate the island with their behavior and actions. It isn't until later that Simon acknowledges that maybe there isn't a physical beast, but that the beast is the boys. Simon is the only character to acknowledge the symbolism of the beast.
As the boys lose touch with civilization, the island is negatively impacted. The boys kill the sow and essentially destroy their food source. The boys also eliminate Simon and Piggy from the island. Lastly, the hunters led by Jack decide to hunt Ralph. To do so, they light a fire to "smoke him out." This fire destroys the majority of the island and ironically plays a role in their rescue. The destruction of the island is significant because it symbolizes the desecration of the last remnants of humanity within the boys.