The Easter Island Heads have proved to be the key to unlocking an anthropological mystery.

Anthropologist Carl Lipo from New York's Binghampton University believes the location of the famous statues shows how ancient Rapa Nui people accessed drinkable water.

Lipo says most of the statues are near the beach, rather than the freshwater lakes in the mountains.

He says this means they likely collected salty water from where the land meets the sea.

"The Rapa Nui people seem to have adapted to it. As long as the salt is lower than the salt itself, people can tolerate that. They probably didn't need to add any salt to their food, but they certainly were able to drink the water."

LISTEN TO CARL LIPO TALK WITH KATE HAWKESBY ABOVE