The loss of innocence is something Ralph laments at the end of the text.

In a way, the tropical island represents a garden paradise, an Eden upon which the innocent boys land. But as the story progresses, the island changes along with the boys, turning from a place of great beauty to a place of great danger.

Innocence is lost in the kicking of a sandcastle and the killing of a suckling pig. The hunt, which begins as a quest for food, becomes an act to quell the blood-lust of the tribe. The death of Simon is terrible, but also exciting for the tribe, hence the cold later death of Piggy and the hunt for Ralph.

These boys are allegories for soldiers in wartime, many of whom reach the front as innocents and even those who return can be said to never really come back at all.