New Historian

Only 15 people required to lift 12-ton hats onto Easter Island statues, research shows

<![CDATA[Of the many mysteries surrounding Easter Island, two questions come up time and again: How did the Rapa Nui people move such great statues across the island? And how did they get the hats onto the statues’ heads? New research from Binghampton University, State University at New York, is on course to answer these questions: by exploring a parbuckling technique used by the Rapa Nui to hoist the hats, or pukao, to the top of the statues, or moai. [caption id="attachment_8697" align="aligncenter" width="500"] Credit: Wikimedia Commons[/caption]

Early transportation technologies on Easter Island

Easter Island sits in the Southern Pacific Ocean and is more than 2,000 miles from Chile in South America. It is about 15 miles long and 7.6 miles wide, with an area of roughly 63 square miles. The famous statues, the moai, were carved from volcanic tuff; while the hats were made of red scoria. Each part came from a different quarry on the island, sparking numerous studies about the technologies used by ancient peoples to transport such heavy goods across many miles. The moai statues, which can be up to 33 feet tall and weigh around 81 tons, are considered to have been moved into place along well-prepared roads using a walking or rocking motion, quite like the way we might move a refrigerator. “We’ve learned they moved the statues in a walking fashion using simple, physics-based processes, in a way that was elegant and remarkably effective,” said Carl Lipo, Professor of Anthropology at Binghamton University. As might be expected, not all of the statues made it to their final locations. Fallen and broken parts of statues show that the statues were originally carved so they leaned forward, for ease of transportation. They were then levelled off once they had reached their destination and were ready for the pukao to be lifted onto them. [caption id="attachment_8696" align="aligncenter" width="500"] Credit: Bjørn Christian Tørrissen via Wikimedia Commons[/caption]

Lifting the pukao of Easter Island: A perplexing concept

Often weighing up to 12 metric tons, pukao are huge cylinders made of red scoria. Despite having relatively few people and a limitation of resources, these heavy carvings were moved across the island. Once they had arrived at the site of the moai, however, they still had to be lifted onto the statues’ heads. It is likely that the islanders then carved the hats, as chips of red scoria are found in the platform of some of the statues. Sean Hixon, lead author of the project and graduate student at Penn State University, says: “Examples of past ideas for pukao transport include sliding the pukao up a wooden ramp or gradually building a pile of stones beneath the pukao. The challenge is to move beyond merely possible transport methods and to identify a transport scenario that is consistent with variation in the archaeological record.”  

Photogrammetry research

Lipo continues: “Our latest study now tackles the issue of the hats, or pukao. These multi-ton stone objects were carved at a separate quarry, transported across the island and somehow raised to the top of the heads of the statues.” Previous researchers have suggested that the statues and hats would have been united before being lifted into place. However, the remnants of broken or abandoned statues indicates that the hats were more likely to have been raised to the top of the already-standing statues. By photographing various pukao and generating 3D models, the research team were able to identify the most likely method of transport for these great statues. “We assumed they were all transported and placed in the same way,” said Hixon. “So we looked for features that were the same on all the hats and all the statues.”  

Parbuckling: highly effective work methods for small groups

The project showed that it is likely for the pukao to have been rolled from the quarry to the site of the moai. The Rapa Nui would have rolled them up large ramps, employing a parbuckling technique. Often used to right ships that have capsized, parbuckling is a simple and efficient technique for rolling objects. The centre of a long rope is fixed to the top of a ramp, and the two ends are wrapped around the cylinder that needs to be moved: in this case, the pukao. “In parbuckling, a line would have been wrapped around the pukao cylinder, and then people would have pulled the rope from the top of the platform,” said Lipo. “This approach minimises the effort needed to roll the statue up the ramp. Like the way in which the statues were transported, parbuckling was a simple and elegant solution that required minimum resources and effort.” As well as reducing the force required to move the hats, this technique also makes it easier to stabilise the hat on its journey up, because typically, it will not roll back down the slope. In fact, the researchers report that 15 or fewer workers could move even the largest of the Easter Island pukao.  

The ingenuity of the ancient people of Easter Island

The research shows the innovative thought processes displayed by the Rapa Nui, helping to challenge some pre-formed ideas about the people. “Easter Island is often treated as a place where prehistoric people acted irrationally, and that this behaviour led to a catastrophic ecological collapse,” said Lipo. “The archaeological evidence, however, shows us that this picture is deeply flawed and badly misrepresents what people did on the island, and how they were able to succeed on a tiny and remote place for over 500 years.” “The answer, like that of our findings with the moai, show that Rapa Nui people were remarkably ingenious and found solutions that required the fewest resources and smallest effort to achieve their goals.” “While the social systems of Rapa Nui do not look much like the way our contemporary society functions, these were quite sophisticated people who were well-tuned to the requirements of living on this island and used their resources wisely to maximize their achievements and provide long-term stability.” Lipo’s team will continue researching the Rapa Nui people and their relationship with their environment and community.]]>
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