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New study helps sort out Easter Island mystery

Easter Island settlements where rainfall was moderate persisted longer, long enough to greet European explorers and colonizers.

By Brooks Hays
Easter Island settlements weren't abandoned as a result of infighting, but because natural resource constraints forced natives to migrate elsewhere. Photo by Julie Cohen/UCSB.
Easter Island settlements weren't abandoned as a result of infighting, but because natural resource constraints forced natives to migrate elsewhere. Photo by Julie Cohen/UCSB.

EASTER ISLAND, Chile, Jan. 27 (UPI) -- Easter Island, famous for its monolithic statues, is a puzzling place. Not only do researchers continue to argue over exactly how the faraway Pacific island came to be inhabited, scientists also debate how it came to be so quickly abandoned. But new research offers some clarity to confusion over the eventual exodus of native Easter Islanders, or Rapa Nui.

While some researchers have posited that the arrival of Europeans (and the diseases they carried with them) was the primary factor that drove out island natives, others say native populations outgrew the island's natural resources and turned against each other -- overpopulation and internal strife. But new analysis says both factors were at play.

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An international team of scientists studied a variety of ancient archaeological sites on the 63-square-mile island, which lies some 2,300 miles off the west coast of Chile. The researchers collected obsidian artifacts and measured how much water had been absorbed by the glass pieces. This analysis combined with knowledge of local climate patterns allowed the scientists to to determine how long various settlements had been inhabited.

The results showed that settlements in areas of the island where rain was either scarce or excessive were short-lived and abandoned prior to the arrival of the Europeans -- suggesting climate challenges and soil overuse played a role in driving out some Easter Islanders.

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"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," explained Oliver Chadwick, a researcher at the University of California, Santa Barbara.

But settlements where rainfall was moderate persisted longer, long enough to greet European explorers and colonizers.

"The area that had relatively high nutrients and intermediate rainfall maintained a robust population well after European contact," Chadwick confirmed.

This suggests Easter Islanders living in the nutrient-rich central portions of the island were able to sustain populations, even under threat of European diseases like smallpox.

"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," Chadwick concluded. "So we see the story as one of pushing against constraints and having to pull back rather than one of violent collapse."

The new study was published this week in the journal PNAS.

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