20 January 2014

Collapse of Easter Island theory

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The accepted view that the islanders degraded their environment so much that they destroyed its ability to provide for them now appears to be wrong.
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Easter Island’s ancient inhabitants were clever agricultural engineers.

Few people get to visit Easter Island, a remote outpost in the South Pacific. But almost everyone has seen pictures of its huge human-figured statues, perched like sentinels in a stark, treeless landscape. The statues were carved between 500 and 1,000 years ago by Polynesians who had colonised the tiny island. These ancient inhabitants, the story goes, cleared lush palm forests for agriculture and overtaxed the island’s fragile environment with their growing numbers. Unable to support themselves on a degraded landscape, the population then rapidly declined by the time of first European contact.

Nobody has done more to popularise this version of events than Jared Diamond, the UCLA geographer and author of numerous bestselling science books, including Collapse: How societies choose to fail or succeed, in which he describes Easter Island as “the clearest example of a society that destroyed itself by overexploiting its own resources”.

But this portrait of prehistoric ecocide is cracking under a mounting body of scholarship. It turns out that the ancient inhabitants, known as the Rapa Nui, were clever agricultural engineers. They created “massive fields fertilised by broken volcanic rocks placed on the surface and in the ground”, write archaeologists Terry Hunt and Carl Lipo in their 2011 book, The Statues that Walked: Unravelling the mysteries of Easter Island. This lithic mulching method transformed marginal soils into an impressive network of food-producing gardens. “If anything, the islanders contributed to an increase in the human carrying capacity of the island over time,” Hunt and Lipo write.

It’s true that the Rapu Nui converted much of the tropical forest into agricultural fields, but this was not done in a reckless, sudden manner, as Diamond and others have postulated. Researchers report in a recent paper in Frontiers in Ecology and Evolution that “the replacement of palm forests by grasslands happened gradually between 500 BCE and 1500 CE.” This was no catastrophic development for the Rapa Nui, much less one that led to their abrupt demise as Diamond has asserted.

The evidence against ecocide continues to mount. In a paper published last year in the Journal of Archaeological Science, anthropologist Mara Mulrooney presented radiocarbon data that shows the island to be utilised from its early settlement, “continuing right through to European contact and the post-contact period”. (Easter Island got its name when the first European traveller visited on Easter in 1722.) Only after Europeans arrived, bringing germs and guns, did the population begin to fall.

“There is very little evidence for the collapse scenario” advanced by Diamond, says Mulrooney, although this does not appear to be a judgment Diamond is prepared to accept, given the testy online exchange he had with Hunt and Lipo shortly after their book was published.

Some years ago in a critical essay on Diamond’s book Collapse,anthropologist Joseph Tainter wrote: “Jared Diamond is a man with a message. Collapse was meant to tell how anthropogenic environmental degradation doomed past societies and, on a grander scale, will undermine us if we don’t change.”

There may well be something to this larger message, but it appears we will no longer find it expressed in the history of Easter Island.

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