Chuck Bednar for redOrbit.com – Your Universe Online
The decline of the Rapa Nui culture predated the arrival of Europeans on Easter Island in 1722, indicating those explorers were not the catalyst that led to their demise, according to new research appearing in the journal Proceedings of the National Academy of Sciences.
In the study, University of California-Santa Barbara professor Oliver Chadwick and an international team of colleagues set out to clarify the factors that contributed to the downfall of the early Rapa Nui society. While they expected to find changes to the culture coincident with the arrival of the Europeans, they found it actually wasn’t the case.
“In the current Easter Island debate, one side says the Rapa Nui decimated their environment and killed themselves off,” said Chadwick, a professor in the UCSB Department of Geography and the Environmental Studies Program. “The other side says it had nothing to do with cultural behavior, that it was the Europeans who brought disease that killed the Rapa Nui.”
“Our results show that there is some of both going on, but the important point is that we show evidence of some communities being abandoned prior to European contact,” he added.
Obsidian answers
Chadwick and archaeologists Christopher Stevenson of Virginia Commonwealth University, Cedric Puleston of UC Davis, and Thegn Ladefoged of the University of Auckland examined six agricultural sites that had been used by the Easter Island inhabitants. They focused primarily on the climate, soil chemistry, and land use trends based on analysis of obsidian spear points.
The researchers used flakes of obsidian, a natural glass formed by volcanic eruption, as a dating tool. They measured how much water had penetrated the surface of the obsidian, which allowed them to determine how long it’d been exposed to water and ultimately conclude the age of those spear point flakes.
Each of the sites was selected because they reflected the diversity of the island. One was near the northwest coast and was in the rain shadow of a volcano, which meant it had low rainfall amounts and a relatively high amount of nutrients available in the soil, the authors said.
The second was on the volcano’s interior side, meaning it had high rainfall, but a low supply of nutrients, while the third was located in another near-coastal area in the northeast. This region was characterized by intermediate amounts of rainfall and relatively high soil nutrients.
“When we evaluate the length of time that the land was used based on the age distribution of each site’s obsidian flakes, which we used as an index of human habitation, we find that the very dry area and the very wet area were abandoned before European contact,” said Chadwick.
The region with relatively high nutrients and intermediate rainfall maintained a robust population well after European contact, he added. Those findings suggest that the Rapa Nui reacted to the factors that prevented sufficient crop growth, and that they were able to maintain a viable culture by producing food in the nutrient-rich region, even when threatened by external factors such as smallpox, tuberculosis, and other diseases brought to the island by Europeans.
“The pullback from the marginal areas suggests that the Rapa Nui couldn’t continue to maintain the food resources necessary to keep the statue builders in business,” the UCSB professor added. “So we see the story as one of pushing against constraints and having to pull back rather than one of violent collapse.”
—–
Follow redOrbit on Twitter, Facebook, Google+, Instagram and Pinterest.
Comments