EASTER ISLAND — Researchers say they have figured out how Easter Islanders transported 13-ton stone hats across the island and placed them on top of 33-feet tall moai statues.
The study, published in the Journal of Archaeological Science, examined how ancient islanders were able to move the additional red stone cylinders, pukao, on tops of the statues, according to NPR.
Easter Island has almost 1,000 moai statues spread across the island, with around 100 of them wearing the pukao hats.
Researchers say the pukao were added later, but are unsure of the exact dates.
After constructing 3D models of the stone cylinders, scientists closely analyzed the details and features of each pukao.
They developed a hypothesis that the hats were rolled up to the top of the statues using long ramps with a technique known as parbuckling.
Archaeologist Carl Lipo, co-author of the study, described the technique being similar to the way barrels used to be loaded onto cargo ships, saying "people would wrap ropes around the center of the barrel and then, from the top of the ramp, pull the barrel up the ramp. … All the attributes we saw match that model."
Using the 3D models, the team was able to calculate how long the ramp would have to be, in addition to how many workers would be required to pull the pukao into place.
With a ramp 75 to 328 feet long, with an incline of 5 to 20 degrees, a team of 15 people could maneuver a pukao into position, according to ArsTechnica.
