Final answer:
The mulberry birthmark boy in 'Lord of the Flies' symbolizes the loss of innocence and the beginning of the boys' descent into savagery, his disappearance marks the first casualty and foreshadows the breakdown of societal norms and the escalation of inherent darkness in human nature.
Step-by-step explanation:
The significance of the mulberry birthmark boy in Lord of the Flies is considerable when examining the theme of loss of innocence and the vanishing of civilized behavior amongst the boys on the island. This character is among the first to vanish, symbolizing the initial disappearance of vulnerable innocence on the deserted island.
The boy with the mulberry-colored birthmark is introduced as one who brings up the notion of the 'beastie,' forecasting the growing fear and eventual descent into savagery that overtakes the boys. As the birthmark boy disappears, it also signifies the first casualty and the subtle beginning of the decline into chaos and the loss of identity.
The absence of his body and the subsequent lack of any formal acknowledgement or mourning from the group reflects on the larger disintegration of social bonds and humaneness within the group who are slowly becoming desensitized to violence and death.
Thus, his presence, and more significantly, his absence, acts as a catalyst for the themes of societal breakdown and the inherent darkness in human nature Golding explores.