By Jason Daley (Smithsonian Magazine)
Archaeologists have figured out a lot about the moai, the giant stone heads found on Rapa Nui or Easter Island, a tiny dot of land in the Pacific Ocean administered by Chile. They know what quarries the stone came from, how they were transported across the island and even how they got their distinctive hats. But one big mystery has remained—why exactly were the giant statues placed in certain spots around the island?
One group of researchers believes they have an answer. Nicola Davis at The Guardian reports archaeologists theorize the location and size of the moai and the monumental raised platforms many of them sit on, called ahu, indicate the presence of fresh water on the island, which has no above ground streams or rivers flowing across it.
The theory emerged when the researchers used spatial modeling to explore the relationship between the locations of 93 of the ahu on the eastern half of the island and available resources. The team looked at the location of marine resources, mulched gardens where crops like sweet potatoes were grown and water resources including wells and seeps where drinkable but brackish freshwater flows out of the ground near the coast at low tide. The study appears in the journal PLOS One.
Wherever water seeped out of the coast, the team found platforms for statues. And in areas in the interior where there were platforms but didn’t seem to be any water, they found the remains of ancient wells that tapped the islands underground aquifers. The size of the statues seemed to correspond to the amount of water available as well. In areas with no water resources, there were no moai or ahu. “Every time we saw massive amounts of fresh water, we saw giant statues,” co-author Carl Lipo from Binghamton University tells Davis. “It was ridiculously predictable.”