The enigmatic statues seen in Rapa Nui, popularly called Easter Island, may have been built by ancient carvers with a belief that the ‘Moai’ monoliths could boost agricultural fertility and critical food supplies, according to a study. The United Nations Educational, Scientific and Cultural Organization (UNESCO) had named Easter Island a World Heritage Site in 1995, with most of the island’s sacred sites protected within the Rapa Nui National Park.
According to the researchers, including those from the University of California - Los Angeles (UCLA) in the US, this is the first definitive study to reveal the site used to build the monoliths as a complex landscape—linking soil fertility, agriculture, quarrying, and the sacred nature of the Moai.
The study, published in the Journal of Archaeological Science, looked at two particular Moai excavated over five years.
These monoliths were discovered in the Rano Raraku quarry on the eastern side of the Polynesian island.
Analysis by the researchers, showed that in addition to serving as a quarry, and a place for carving statues, Rano Raraku was also the site of a productive agricultural area.
“Our excavation broadens our perspective of the Moai, and encourages us to realize that nothing, no matter how obvious, is ever exactly as it seems. I think our new analysis humanizes the production process of the Moai,” said study co-author Jo Anne Van Tilburg from UCLA.
Chemical analysis of Rano Raraku soil, and those in other parts of the island revealed that the quarry probably had the richest minerals on the island, certainly over the long term, the researchers said.
Coupled with a fresh-water source in the quarry, they said, the practice of quarrying seemed to boost soil fertility, and food production in the immediate surroundings.
According to the study, soils in the quarry are rich in clay created by the weathering of lapilli tuff—the local bedrock—as the ancient indigenous workers carved into deeper rock and sculpted the Moai.
“There were really high levels of things that I never would have thought would be there, such as calcium and phosphorous. The soil chemistry showed high levels of elements that are key to plant growth and essential for high yields,” said study co-author Sarah Sherwood.
She said the soil was being quickly worn out everywhere else on the island -- eroding, being leeched of elements that feed plants.
But in the quarry, Sherwood noted, with its constant new influx of small fragments of the bedrock generated by the quarrying process, there was a perfect feedback system of water, natural fertilizer, and nutrients.
The study also revealed that the ancient indigenous people of Rapa Nui were very intuitive about what to grow—planting multiple crops in the same area—helping maintain soil fertility.
While previous research of the enigmatic statues had postulated that they were lined up to be exported to another place, the Moai excavated in the current study were discovered upright in place—one on a pedestal and the other in a deep hole—indicating they were meant to remain there.
“This study radically alters the idea that all standing statues in Rano Raraku were simply awaiting transport out of the quarry. That is, these and probably other upright Moai in Rano Raraku were retained in place to ensure the sacred nature of the quarry itself,” Van Tilburg said.
According to the researchers, the Moai were central to the ancient indigenous people’s idea of fertility.
The study estimated that the statues from the inner quarry were raised by or before A.D. 1510 to A.D. 1645.
According to the scientists, the activity in this part of the quarry most likely began in A.D.1455, with most production of Moai ceasing in the early 1700s due to contact with western civilisations.
The Moai excavated by Van Tilburg and her team had been almost completely buried by soils and rubble.
“We chose the statues for excavation based on careful scrutiny of historical photographs and mapped the entire Rano Raraku inner region before initiating excavations,” she said.
Adding the inputs gleaned from the current study, the researchers have created a massive detailed archive documenting more than 1,000 sculptural objects on Rapa Nui, including the Moai, as well as similar records on more than 200 objects scattered in museums throughout the world.