How did Easter Island's ancient statues lead to the destruction of an entire ecosystem?


Jul 4, 2007

The giant stone statues of Easter Island have perplexed generations of archaeologists, engineers and scholars. Ever since European explorers first set eyes on them three centuries ago these carvings have presented a problem. How could the island's primitive inhabitants have erected such massive edifices – each weighing many tons – without the help of wheels, cranes, machines, metal tools or draft animals? The very existence of these giant heads on a barren outcrop of land in the middle of the Pacific Ocean seemed to defy reason, if not the laws of physics.

The author Erich von Däniken suggested that the statues were the work of extraterrestrial beings who, after being stranded on Easter Island, decided to do a little stonework before eventually being rescued. It was hard to believe that the stones were the work of humans, especially ones who had to survive in the treeless landscape of Easter Island, which lies more than 2,000 miles from the nearest mainland.

Jacob Roggeveen, the Dutch seaman who gave the island its name when he spotted it on Easter Day in 1722, was amazed by the statues. "The stone images at first caused us to be struck with astonishment, because we could not comprehend how it was possible that these people, who are devoid of heavy thick timber for making any machines, as well as strong ropes, nevertheless had been able to erect such images, which were fully 30ft high and thick in proportion," Roggeveen wrote in his journal.

He was equally amazed as to how the Easter islanders could have come to colonise such a remote place in the middle of a vast ocean. Their canoes were leaky and frail, made of small planks and light inner timbers stitched together by fine, twisted threads. They were not the sort of heavy ocean-going craft that could survive a three-week journey over open sea. Much bigger timbers bound with heavy ropes were needed for that.

Yet there were no trees, no timber and no ropes to be seen. Easter Island seemed to be a place of "singular poverty and barrenness", Roggeveen wrote.

However, we now know that Easter Island was once a lush, sub-tropical paradise covered in thick forest filled with a rich assortment of wildlife. But the trees and forest animals were long gone by the time Roggeveen had arrived. The question is why?

This Saturday the giant statues, or "moai", could be voted one of the new seven wonders of the world in a global competition. At least 50 million people have taken part in the attempt to comprise a 21st-century list of man-made heritage sites. The seven winners from the 20 entries will be announced in Lisbon at the end of the week.

The moai stones lie at the heart of the many mysteries of Easter Island. But trying to explain the puzzle has caused a deep fissure within academia. Some archaeologists see Easter Island as an example of what can happen when the lust for material splendour – ever bigger stone carvings in this case – is satisfied at the expense of the environment.

Others, meanwhile, take a different view. They see Easter Island as another victim of European colonialism that killed off an ancient culture. The island, these scholars argue, suffered at the hands of introduced diseases, notably smallpox, and a slave trade that stole a huge proportion of its indigenous population.

At the heart of the debate is the issue of the island's deforestation. There is no dispute that the island was once covered in huge palm trees. There is also no dispute that something happened that caused the island to become completely denuded over a short period of time. But was it the islanders who triggered this environmental degradation, or some other event beyond their control such as climate change or the introduction of rats?

In his 2005 book Collapse, author Jared Diamond explains why it was the islanders' fault. Diamond says they started to build bigger and bigger ceremonial statues in an atmosphere of competitive rivalry between the island's many different clans. To move the statues from the island's quarry, Rano Raraku, in the south-east, the islanders needed to cut large logs for the construction of long "canoe ladders" to carry the massive carvings to the island's coast. They also needed heavy ropes made from the fibrous bark of the bigger palms.

The scale of the operation was vast. Crews of between 50 and 500 men dragged statues weighing between 10 and 90 tons. Some 887 statues were carved in total, nearly half of which still remain in Rano Raraku quarry, which appears to have been abandoned mid-production. For its transport alone, each statue would have required several trees to be cut down. Other timber was needed for housing, fuel and the construction of the large stone platforms, or "ahu", on which the moai were placed.

"The overall picture for Easter Island is the most extreme example of forest destruction in the Pacific, and among the most extreme in the world: the whole forest gone, and all of its tree species extinct," says Diamond.

As a result of the deforestation, food production fell dramatically as crops became exposed to the harsh winds and semi-arid conditions of the region. Consequently the population collapsed from perhaps as many as 15,000 at its peak to the few thousand that were eking out a living by the time Roggeveen arrived.

Smallpox and slavery killed off most of the people that remained, but the islanders were on the way to total collapse even without any contact with Europeans, says Diamond.

But not everyone is convinced. "It's a shame that some now want to blame the islanders for their own demise," says Professor Terry Hunt, an anthropologist at the University of Hawaii. "There is no evidence that a population collapse occurred before European contact," says Hunt, who is supported by Professor Carl Lipo of California State University in Long Beach. "Lacking much of the basic evidence, a set of beliefs has been established and perpetuated that rationalise the story," says Lipo.

Hunt and Lipo argue that Easter Island was first colonised by Polynesian seafarers much later than supposed. They say the first people to arrive on Easter Island came around AD1200, about 400 years later than other scientists have suggested from radio-carbon dating. This makes it implausible for the population to reach the 15,000 figure that would have caused the fast ecocide invoked by the environmental catastrophists.

Hunt and Lipo believe the deforestation occurred over a longer period as a result of climate change, aided probably by rats. The islanders did not go through a population collapse until after the arrival of Europeans, they say.

However, John Flenley of Massey University in New Zealand, who carried out much of the radio-carbon work on Easter Island, and Paul Bahn, a leading British archaeologist, say there is ample evidence for a much earlier arrival of Polynesian settlers. They dismiss the sceptics. "They view the island through rose-coloured spectacles, choosing to believe that the community was thriving up to 1722 and that it was the Europeans who destroyed them," say Flenley and Bahn in a scientific paper published in the May issue of the Rapa Nui Journal.

"It is undeniable that many calamities befell the island thanks to European visits... but the Europhobic model ignores the mass of archaeological, oral, botanical and sedimentological evidence which documents the prehistoric transformation of the island by humans from pristine subtropical rainforest to a virtually treeless landscape," they say.

Climate change may have contributed to deforestation but it could not be solely responsible. Neither could rats have killed off the living trees which can live for a century or more. The radio-carbon dating points convincingly to an initial colonisation before AD900, Flenley and Bahn argue. There was ample time for the rapid deforestation, environmental collapse and a population crash, they insist.

Why all this is important today is not of course lost in the age of globalisation, climate change and a rapidly growing world population of more than 6.5 billion people. As Jared Diamond says: "The parallels between Easter Island and the whole of the modern world are chillingly obvious."

The tale of the heads

* Easter Island lies 2,237 miles west of Chile – which annexed it in 1888 – and was formed by the three volcanoes as they emerged from the floor of the Pacific Ocean.

* It is one of the most remote inhabited islands and was first colonised by Polynesian seafarers sailing from islands to the west which were already inhabited.

* The stone carvings, or moai, probably represent ancestral deities linked with the 20 or so clans that comprised the island's population. The statues were usually placed on a stone platform, or ahu, sited on the coast. They faced inland, overseeing the segment of land controlled by each clan.

* A quarry called Rano Raraku is where most of the statues were carved from hardened volcanic ash before being transported to their final resting site. Many statues are still in the quarry today, including the biggest, weighing nearly 155 tons, which probably turned out to be too large to be removed.