By Ian Steadman, Wired UK

The giant statues of heads on Easter Island, the moai, have posed an enduring problem for archaeologists — how did their creators move them? The most popular hypothesis is that they were rolled across the island on wooden logs, but one anthropologist has proposed a more unusual possibility — that they “walked.”

[partner id=”wireduk” align=”right”]Carl Lipo, from California State University, has demonstrated that three teams of workers can, using ropes, “walk” a 4.35-tonne replica moai down a path just like the ones that cover Easter Island.

The study, published in the Journal of Archaeological Science, doesn’t just look at the moai that were successfully placed on stone pedestals, but also those which were clearly abandoned alongside roads in the process of being moved — those abandoned moai show clear signs of having fallen over from upright positions, and at least one shows signs of attempts to re-raise and walk out again. It’s strong evidence that wood rollers would not have been the method used by the Rapa Nui people.

Nature has a video from Lipo showing how he and his team pulled off the walk — three ropes are attached to the moai’s head, with two teams pulling forward on either side and one team staying directly behind to steer the statue and prevent it falling forward. Attempts were made by a team in 1986 to walk statues of varying heights this way, but the experiment was halted after large chips of stone began to come off the bases of the statues under the stresses of walking. While walking was clearly possible, the damage it would cause seemed to rule it out as the likely method used to shift the moai into place.

Lipo and his team, though, looked for more evidence that walking was possible, and found that the archaeological evidence from the quarries where the statues were carved still indicated they were moved while upright. “The figure is usually shaped from the top down leaving a narrow ‘keel’ connecting it to the bedrock,” wrote Lipo and colleagues in their article. “Statues were ‘walked’ out of the pit through excavated openings to moai roads.” The roads that criss-cross Easter Island are the right shape for the statues to fit into without toppling too easily too the side (narrow and concave), too.

They measured the dimensions of each moai statue, too, and found that, when modelled on a computer, they should have been able to walk them using ropes — and sure enough, after a bit of heaving and ho-ing, the moai walked.

Interestingly, analysis of the moai, which are often found half-buried or broken alongside the roads, showed a different distribution of weight — the road moai tended to have a centre of gravity which was much further forward, which could mean that the Rapa Nui workers found it harder to prevent them toppling over in transit.

The dominant rival hypothesis is that the statues were rolled along roads using wooden logs, which would have tied into the archaeological record that showed the number of trees on the island declined precipitously in the same era the production of moai ceased. This also ties into the neat little environmental fable that Easter Island is a good example of an ecosystem driven to destruction by human overexploitation — the island, once covered with huge, lush palm trees, was entirely treeless by the time European explorers arrived in the 1700s.

The moai represent the ancestors the Rapa Nui people worshiped as part of their religion, but as the ecosystem of the island deteriorated with the loss of trees civil war broke out and, reportedly, cannibalism become common. By the time Jacob Roggeveen visited in 1722 the island’s population had dropped to somewhere between 1,000 and 2,000, down from a peak of around 15,000 a few centuries earlier. Whether the deforestation that set off this chain of events was due to the construction of the moai is still unclear.

Source: Wired.co.uk