The giant heads, carved centuries ago by the island’s inhabitants, represent the living ancestors of Easter Island’s Polynesian people - the Rapa Nui - and have brought it UNESCO World Heritage Site status. Dozens of giant “Moai” statues dominate the hillsides surrounding the island’s Rano Raraku wetland, but they are facing the threat of what locals describe as a kind of leprosy, white spots that are appearing on their iconic facades.