Washington: A new study has provided a deeper insight into how did the Rapa Nui society really declined on Easter Island.
The research by a group of international researchers, including UC Santa Barbara's Oliver Chadwick, offers a different explanation and helps to clarify the chronological framework.
The investigators expected to find that changes coincided with the arrival of the Europeans, but their work shows instead that the demise of the Rapa Nui culture began prior to that.
It suggested that the Rapa Nui reacted to regional variations and natural environmental barriers to producing crops rather than degrading the environment themselves.
They were able to maintain a viable culture even under the threat of external factors, including European diseases such as smallpox, syphilis and tuberculosis.
Oliver Chadwick joined archaeologists Christopher Stevenson of Virginia Commonwealth University, Cedric Puleston of UC Davis and Thegn Ladefoged of the University of Auckland in examining six agriculture sites used by the island's statue-building inhabitants.
Their research focused mainly on the three sites for which they had information on climate, soil chemistry and land use trends as determined by an analysis of obsidian spear points.
These included a mix of low rainfall and relatively high soil nutrient regions, high rainfall and low nutrient supply, intermediate amounts of rainfall and relatively high soil nutrients.
The study sites reflected the environmental diversity of the roughly 100 square kilometre island situated off the west coast of Chile.
The team used flakes of obsidian, a natural glass, as a dating tool. Measuring the amount of water that had penetrated the obsidian's surface, allowed the researchers to determine its age.
Chadwick concluded that the demise of the infamous Polynesian culture on Easter Island was a story of pushing against constraints and having to pull back, rather than one of a violent collapse from environmental degradation or disease.
The study is published in the Proceedings of the National Academy of Sciences.