What is the significance of the “world of grownups" throughout the novel Lord of the Flies?

At the end of Chapter 5, Ralph and Piggy lament about their situation and wish that there were "grownups" around to take control of the situation. Piggy comments,

"Grownups know things...They wouldn't quarrel---" (Golding 94).

Then, Ralph desperately says,

"If only they could send us something grownup...a sign or something" (Golding 94).

The next chapter opens with an air battle taking place about ten miles above the island. A paratrooper is shot out of the sky and descends onto the island. Ironically, the "sign" from the grownups is actually a dead paratrooper. It is significant to note that the same barbaric, savage behavior that is prevalent throughout the island, is also common in the "world of grownups." Adults are plagued with the same inherent wickedness as the boys, and therefore behave like savages by going to war against one another. While Piggy and Ralph look up to adults, they naively believe that the "adult world" is less savage and more structured. Golding is suggesting that human wickedness and affinity for violence is prevalent from youth to adulthood, and the most obvious example of disregard for humanity is in the event of war. At the end of the novel, a naval officer lands on the island just as Ralph escapes the forest fire with the savages at his heels. The naval officer says,

"I should have thought that a pack of British boys---you're all British, aren't you?---would have been able to put up a better show than that---I mean---" (Golding 202).

His comments are hypocritical because he is actually a participant in a war, which is essentially no different than the boys dressing up like savages and hunting Ralph. It turns out that the "world of grownups" is just as depraved as the boys' savage society on the island.