Easter Island’s famous statues were created as freshwater landmarks, according to new research.
They enabled the inhabitants to quickly find places where they could drink – so they would not go thirsty.
The simple explanation solves a riddle that has baffled the world for centuries, say scientists.
And it suggests the ancient civilisation was a peaceful and caring society – rather than warmongering as has been suggested.
Study co author Dr Terry Hunt, of the University of Arizona in the US, said: “The monuments and statues are located in places with access to a resource critical to islanders on a daily basis – fresh water.
“In this way, the monuments and statues of the islanders’ deified ancestors reflect generations of sharing, perhaps on a daily basis – centered on water, but also food, family and social ties, as well as cultural lore that reinforced knowledge of the island’s precarious sustainability.”
The internationally renowned anthropologist added: “And the sharing points to a critical part of explaining the island’s paradox.
“Despite limited resources, the islanders succeeded by sharing in activities, knowledge, and resources for over 500 years until European contact disrupted life with foreign diseases, slave trading, and other misfortunes of colonial interests.”
The 887 monolithic stone heads, or ‘moai’, and their huge platforms, or ‘ahu’ are dotted about the remote Pacific island in eastern Polynesia.
They were carved by the Rapa Nui people between1250 and 1500 – but their purpose has been a mystery.
Now a study, published in the journal PLOS ONE, has found they were built close to the island’s limited coastal freshwater sources.
It shows the people were smarter and more cooperative than ever imagined, helping to sustain a population of thousands.
They worked together to make and move the enormous monuments. It is known they they crafted numerous tools from volcanic glass for multiple tasks – including carving.
Co author Professor Carl Lipo, of Binghamton University, New York, said: “The issue of water availability, or the lack of it, has often been mentioned by researchers who work on Easter Island.
“When we started to examine the details of the hydrology, we began to notice that freshwater access and statue location were tightly linked together.”
His team used a mathematical technique called quantitative spatial modeling to identify a relationship between the location of the statues and natural materials.
These included the mulching of agricultural fields and gardens with stone tools – which is typical of a dryland environment.
The two other most critical supplies on easter Island were marine and freshwater sources.
Prof Lipo said: “It wasn’t obvious when walking around – with the water emerging at the coast during low tide, one doesn’t necessarily see obvious indications of water.
“But as we started to look at areas around ahu, we found that those locations were exactly tied to spots where the fresh groundwater emerges – largely as a diffuse layer that flows out at the water’s edge.
“The more we looked, the more consistently we saw this pattern. Places without ahu/moai showed no freshwater. The pattern was striking and surprising in how consistent it was.
“Even when we find ahu/moai in the interior of the island, we find nearby sources of drinking water. This paper reflects our work to demonstrate that this pattern is statistically sound and not just our perception.”
The statues are massive, up to 40 feet (12 metres) tall and 75 tons in weight. They were decorated on top with ‘Pukao,’ a soft red stone in the shape of a hat. They also have torsos under the heads.
Researchers have long wondered why ancient people built the monuments in their respective locations, considering how much time and energy was required to construct them.
Lead author Robert DiNapoli, a PhD student in anthropology at the University of Oregon, added: “Many researchers, ourselves included, have long speculated associations between ahu/moai and different kinds of resources such as water, agricultural land, areas with good marine resources, etc.
“However, these associations had never been quantitatively tested or shown to be statistically significant.
“Our study presents quantitative spatial modeling clearly showing that ahu are associated with freshwater sources in a way that they aren’t associated with other resources.”
The researchers currently only have comprehensive freshwater data for the western portion of the island.
They plan to do a complete survey of the island in order to continue to test their theory of the relation between the statues and freshwater.
In their remote location off the coast of Chile, the ancient inhabitants of Easter Island were believed to have been wiped out by bloody warfare, as they fought over the island’s dwindling resources.
But Prof Lipo believes the lost civilisation was destroyed by outside inlfuences , through no fault of their own. The latest findings back this idea.
His previous research has shown some areas close to the shores had a salt concentration low enough for humans to safely drink.
European accounts of first encounters with the island in the 18th century include passages where the natives appear to simply drink seawater.
Since the human body cannot process the high salt concentration of seawater, this supports the team’s groundwater discharge theory.
The process of coastal groundwater discharge makes it possible for humans to collect drinkable freshwater directly where it emerges at the coast of the island.
All the statues have overly-large heads and are thought to be living faces of deified ancestors. They have an average height of 13ft (four metres).
Nobody really knows how the colossal stone statues that guard Easter Island were moved into position.
Nor why during the decades following the island’s discovery by Dutch explorers in 1722, each statue was systematically toppled, or how the population of Rapa Nui islanders was decimated.
Shrouded in mystery, this tiny triangular landmass, stranded in the middle of the South Pacific and 1,289 miles from its nearest neighbour, has been the subject of endless books, articles and scientific theories.
All but 53 of the Moai were carved from tuff , compressed volcanic ash. In 1979 archaeologists said the statues were designed to hold coral eyes. The figures are believed to be symbol of authority and power.
They may have embodied former chiefs and were repositories of spirits or ‘mana’.
They are positioned so that ancient ancestors watch over the villages, while seven look out to sea to help travellers find land.
In their remote location off the coast of Chile, the ancient inhabitants of Easter Island were believed to have been wiped out by bloody warfare, as they fought over the island’s dwindling resources.
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