Easter Island: Mysterious Arrangement of Rapa Nui Statues Finally Explained

"This work has been tremendously exciting and fulfilling for me."

Mysterious, statue-laden Rapa Nui, dubbed Easter Island by European colonizers, is not an easy place to thrive. At more than 2,000 miles from the coast of South America, it is one of Earth’s most remote inhabited islands. The soil is poor in nutrients, rainfall is unpredictable, and while there are freshwater lakes within its volcanic craters, there are no streams or other sources of surface freshwater. These ecological constraints, argue scientists in a new PLOS One study, are the key to solving the long-standing mystery of its statues.

From about the 13th century to the moment of European contact in 1722, the Rapa Nui people constructed over 300 megalithic platforms, called ahu, and nearly 1,000 multi-ton anthropomorphic statues, called moai. For a long time, it was unclear what these massive statues represented or why they stood where they stood. But now, the authors of the new study argue that the moai were carefully placed in relation to fresh water.

“These results are significant because they clearly show that ahu locations are related to freshwater sources in a way that they aren’t associated with other environmental factors, which resolves previous debates about why they occur where they do, and it allows us to look deeper into why this pattern occurs,” study co-author and University of Oregon Ph.D. student Robert DiNapoli, tells Inverse.

Rapa Nui, or Easter Island.

Antti Lipponen/Flickr

DiNapoli and his co-authors aren’t saying that the monuments are necessarily like bread crumbs leading the way to a drink, but it’s hard to argue with what they found: Every time they found large amounts of fresh water on the island, the giant statues were nearby.

DiNapoli notes that archeologists often view monumental structures — whether it’s a pyramid or a moai — as places that perform multiple social roles and functions. A monolith, in other words, can serve both spiritual and practical uses. In the paper, the team argues that Rapa Nui’s monuments are partially related to community competition and cooperation centered around the island’s limited freshwater sources.

“While basically everyone agrees that they are ritual, religious sites and clearly have a coastal distribution,” says DiNapoli, many researchers have argued that they could also be related to social factors, like cooperation and competition for agricultural land, marine food, and freshwater. The team’s goal was to test those ideas with rigorous statistical modeling. Focusing on the east side of the island, where local resources had previously been mapped, the team investigated whether there were any relationships between the distribution of 93 ahu and the supplies necessary for life.

There didn’t appear to be a link between monument location and marine food or agricultural land, but the team did find a spatial relationship between monuments and the island’s limited freshwater sources. This may mean that the monuments were built, in part, to signal territorial resource control.

Archaeological investigation has revealed new details about the societies on Easter Island.

Flickr / Arian Zwegers

This freshwater theory has some critics, but DiNapoli and his colleagues are the first to examine the idea that the island’s ecology constrained its inhabitants’ options for subsistence, and these environmental constraints, in turn, are a key factor in the emergence of the Rapa Nui statues. DiNapoli and his team believe that, like oceanic islands, Rapa Nui can “offer a model system for understanding human-environment interactions.”

“It was amazing to me that the ancient Rapa Nui people invested so much time and energy to build hundreds of massive monumental structures on such a tiny, remote, and resource-poor island,” DiNapoli says. “This work has been tremendously exciting and fulfilling for me.”

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