Easter Island Settled Later, Depleted Quicker Than Thought?
for National Geographic News
|March 9, 2006|
New archaeological evidence suggests that Easter Island, mysterious home
of titanic stone heads, was first settled around A.D. 1200, much later
than previously thought.
Once there, the colonizers quickly began erecting the famous statues for which the remote eastern South Pacific island (map) is famous. They also helped deplete the island's natural resources at a much faster rate than previously thought, the study says.
With its barren landscape, the Chilean-controlled island, also known as Isla de Pascua and Rapa Nui, has come to symbolize an isolated civilization that once flourished but suffered ecological catastrophe.
Terry Hunt, the study's lead author, says the new findings highlight the dangers of human-induced environmental change, especially to islands.
"This shows that [such] changes can occur very rapidly," said Hunt, an anthropology professor at the University of Hawaii in Honolulu.
The study is to be published in tomorrow's issue of the journal Science.
Scientists have long treated Easter Island's extinct society as a textbook example of a once thriving civilization that doomed itself by wiping out its natural resources.
Before humans arrived on the isolated island, which is 64 square miles (166 square kilometers) in area, had some 16 million giant palm trees. Twenty or more other tree and woody shrub species formed a forest on the island, as on other local islands.
Yet when Dutch colonizers arrived on Easter Island in 1722, they found the eerie stone carvings and little else.
The natural landscape was totally barren, the island's trees having been cut downan environmental disaster examined in geographer Jared Diamond's latest best seller, Collapse: How Societies Choose to Fail or Succeed. (See Guns, Germs and Steel: Jared Diamond on Geography as Power.)
In 1947 Norwegian explorer Thor Heyerdahl sailed a tiny raft, called Kon-Tiki, from Peru to Polynesia in an effort to prove that ancient civilizations could have sailed to the South Pacific.
Relying in part on Heyerdahl's conclusions, scientists have long believed the island was colonized around A.D. 400. More recently, researchers argued that settlement first took place around the year 800.
The deforestation of Easter Island is believed to have begun around 1300, suggesting that there was a period of several centuries during which the islanders lived in harmony with the environment.
Fuel for the Fire
The new study by Hunt and his colleague Carl Lipo, however, suggests that the Polynesians didn't arrive until around 1200. The deforestation began soon thereafter, they say.
The scientists took eight samples of wood charcoal from the bottom of the oldest known archaeological site on the island, Anakena. Radiocarbon dating placed them at around the year 1200.
"This is the first sign of human activity at Anakena and probably for the island," Hunt said. "There is no longer any evidence for settlement earlier than about 1200 A.D."
The findings suggest the island did not enjoy the kind of Garden of Eden period for 400 to 800 years that researchers had previously imagined.
Instead the Polynesians immediately began destroying the trees and giant palms, using the wood for their canoes, for fires, and perhaps for moving statues.
"Radiocarbon dates show that deforestation took place over 400 to 500 years," starting around 1200, Hunt said.
"This is consistent with our shorter chronology and the observations made by the Dutch in 1722."
Most of the island animals, particularly birds, lost their habitat and were wiped out. Native animals also suffered direct predation from the Polynesian rat, which the colonizers brought with them to the island.
"Like problems of invasive species today, [the rat] probably had a widespread and devastating impact on the island's ecologyparticularly the palm trees and also directly or indirectly on birds," Hunt said.
"Rats would grow to huge numbers and consume the seeds of trees, and regeneration of the forest would essentially stop."
The new results appear to back up other recent studies that suggest later dates for colonization of islands in the region.
For example, it is now thought that New Zealand was colonized after 1200, about 400 years later than has long been assumed.
To understand the functioning of island ecosystems, it is important to sort out natural processes from human impacts. This requires dependable time lines of human habitation.
"This need for reliable chronologies is especially magnified for Pacific islands, because in so many cases the advent of human settlement has led to massive alteration of the natural landscapes," said Stephen Athens, general manager of the nonprofit International Archaeological Research Institute, Inc., in Honolulu.
Athens, who was not involved with the new study, says a relatively late settlement of Easter Island is to be expected, given the revised chronologies of its neighbors in eastern Polynesia.
"One of the most significant conclusions we can draw from studies [like these] is just how extremely sensitive the natural ecosystems of many islands are to the advent of humans, with the degree of sensitivity apparently related to isolation and endemism of the fauna and flora," Athens said. "Endemism" refers to species that are found naturally in only one location.
In the case of Easter Island, Athens said, "we are indeed seeing humans initiating ramifying processes over which they lose control."
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