Clash looms over Easter Island theory with a message for today

Rapa Nui Moai statues. Photo / Supplied

A scientific battle over the fate of Easter Island's natives is ready to erupt with the publication of a book challenging the theory that they committed ecological suicide.

The debate has a modern political dimension. At stake is the central example, cited by Jared Diamond in his 2005 book Collapse: How Societies Choose to Fail or Succeed, of the dire consequences that threaten if humans don't take care of the planet.

At the core of the archaeological argument are the moai, hundreds of stone statues that line the coast of the now treeless South Pacific island, known to its inhabitants as Rapa Nui.

The almost-naked natives discovered by a Dutch expedition on Easter Sunday 1722 were considered too impoverished to have carved and moved the statues themselves.

The accepted theory is that a more advanced population of about 15,000 people erected the statues, with hundreds of men hauling them to the shore and industries devoted to making ropes, rollers and sledges while the rest struggled to feed the workers.

After the last of the island's giant palm trees was felled, the theory suggests, its ecology collapsed, food production crashed and civil war ensued, leading eventually to cannibalism and leaving the remnants of the population to eke out an existence until the Dutch arrived.

But the revisionists, led by archaeologists Carl Lipo of California State University and Terry Hunt of the University of Hawaii, say the superior society never existed.

The Rapa Nui culture, Dr Lipo says, was wiped out after Europeans arrived, bringing epidemics of disease, including TB and leprosy.

Illness, enslavement and land theft reduced the population from an estimated 3000 to just 111 by 1877.

In their book, The Statues that Walked: Unravelling the Mystery of Easter Island, to be published in June, Dr Lipo and Professor Hunt present their evidence that Polynesian colonists arrived in 1200 - up to 800 years later than the conventional theory claims - and immediately changed the environment with slash-and-burn agriculture.

The effect this had on the giant palm forest was magnified by the rats that arrived with them.

Dr Lipo says deforestation didn't make things much worse for humans.

Rapa Nui was no tropical paradise. It's an old volcanic island and many of the nutrients in the soil had already been washed away.

Burning the giant palms helped, but the settlers soon turned to a technique called stone mulching, in which freshly broken volcanic rocks were planted in the poor soil to add nutrients and cut down on erosion.

The same people who used rock mulching and greeted the Dutch could have moved the moai from Rano Raraku, the quarry where they were carved, to the shore, he says. The statues seem designed to allow small groups of men to move them by rocking them and shuffling them along, as you would a refrigerator.

Defenders of the old theory are not taking this lying down.

British archaeologist Paul Bahn and his co-author John Flenley are bringing out a third edition of The Enigmas of Easter Island with a response to the upstarts.

"They're ignoring the oral tradition and just cherry-picking the data they like," he said.

- INDEPENDENT