Tuesday, September 10, 2013

In which I am reminded that facts are open to interpretation

In the National Geographic issue on Easter Island:

Jared Diamond drew heavily on Flenley’s work for his assertion in Collapse, his influential 2005 book, that ancient Easter Islanders committed unintentional ecocide. They had the bad luck, Diamond argues, to have settled an extremely fragile island—dry, cool, and remote, which means it’s poorly fertilized by windblown dust or volcanic ash. (Its own volcanoes are quiescent.) When the islanders cleared the forests for firewood and farming, the forests didn’t grow back. As wood became scarce and the islanders could no longer build seagoing canoes for fishing, they ate the birds. Soil erosion decreased their crop yields. Before Europeans showed up, the Rapanui had descended into civil war and cannibalism. The collapse of their isolated civilization, Diamond writes, is “the clearest example of a society that destroyed itself by overexploiting its own resources” and “a worst-case scenario for what may lie ahead of us in our own future.”
The moai, he thinks, accelerated the self-destruction. Diamond interprets them as power displays by rival chieftains who, trapped on a remote little island, lacked other ways of strutting their stuff. They competed by building ever bigger statues. 

I thought he made a very good argument based on his presentation of the evidence. However:
Rearrange and reinterpret the scattered shards of fact, though, and you get a more optimistic vision of the Rapa Nui past—that of archaeologists Terry Hunt of the University of Hawaii and Carl Lipo of California State University Long Beach, who have studied the island for the past decade. It’s a vision peopled by peaceful, ingenious moai builders and careful stewards of the land. Hunt and Lipo agree that Easter Island lost its lush forests and that it was an “ecological catastrophe”—but the islanders themselves weren’t to blame. And the moai certainly weren’t. There is indeed much to learn from Easter Island, Hunt says, “but the story is different.”

His and Lipo’s controversial new version, based on their research and others’, begins with their own excavation at Anakena beach. It has convinced them that the Polynesians didn’t arrive until A.D. 1200, about four centuries later than is commonly understood, which would leave them only five centuries to denude the landscape. Slashing and burning wouldn’t have been enough, Hunt and Lipo think. Anyway, another tree killer was present. When archaeologists dig up nuts from the extinct Easter Island palm, the nuts are often marred by tiny grooves, made by the sharp teeth of Polynesian rats.

The rats arrived in the same canoes as the first settlers. Abundant bones in the Anakena dig suggest the islanders dined on them, but otherwise the rodents had no predators. In just a few years, Hunt and Lipo calculate, they would have overrun the island. Feasting on palm nuts, they would have prevented the reseeding of the slow-growing trees and thereby doomed Rapa Nui’s forest, even if humans hadn’t been slashing and burning. No doubt the rats ate birds’ eggs too.
Of course, the settlers bear responsibility for bringing the rats; Hunt and Lipo suspect they did so intentionally. (They also brought chickens.) But like invasive species today, the Polynesian rats did more harm to the ecosystem than to the humans who transported them. Hunt and Lipo see no evidence that Rapanui civilization collapsed when the palm forest did; based on their own archaeological survey of the island, they think its population grew rapidly after settlement to around 3,000 and then remained more or less stable until the arrival of Europeans.

Cleared fields were more valuable to the Rapanui than palm forests were. But they were wind-lashed, infertile fields watered by erratic rains. Easter Island was a tough place to make a living. It required heroic efforts. In farming, as in moai moving, the islanders shifted monumental amounts of rock—but into their fields, not out. They built thousands of circular stone windbreaks, called manavai, and gardened inside them. They mulched whole fields with broken volcanic rocks to keep the soil moist and fertilized it with nutrients that the volcanoes were no longer spreading. In short, Hunt, Lipo, and others contend, the prehistoric Rapanui were pioneers of sustainable farming, not inadvertent perpetrators of ecocide. “Rather than a case of abject failure, Rapa Nui is an unlikely story of success,” Hunt and Lipo argue in their recent book.

It’s called The Statues That Walked, and the Rapanui enjoy better spin in it than they do in Collapse. Hunt and Lipo don’t trust oral history accounts of violent conflict among the Rapanui; sharp obsidian flakes that other archaeologists see as weapons, they see as farm tools. The moai helped keep the peace, they argue, not only by signaling the power of their builders but also by limiting population growth: People raised statues rather than children. What’s more, moving the moai required few people and no wood, because they were walked upright. On that issue, Hunt and Lipo say, evidence supports the folklore.

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