To test the walking hypothesis, Lipo and colleagues built a 4.35-ton concrete statue, which they say is a "precise proportionally scaled replica of an actual road moai shaped appropriately for transport."
Then they tested its upright movement at Kualoa Ranch in Hawaii.
Chanting "heave-ho," a team of 18 people managed to get the statue walking using three hemp ropes.
One was tied from behind near the top of the head at the eyes to keep the statue from falling on its face. The other two, tied to the same location at the eyes, were stretched on either side and pulled in alternating fashion to rock the statue.
"Each roll caused the statue to take a step," Lipo said.
In under an hour, the statue traveled 100 meters.
"In contrast to popular notions of sledges, rollers or sliders of trees, the evidence shows that moai were specifically engineered to 'walk' in an upright position achieved using only ropes, human labor and simple cleared pathways," wrote the researchers.
They noted that material for ropes was abundant on the island since they were made from a woody shrub. Therefore, "statue making and transport cannot be linked to deforestation," they said.