Rapa Nui moai moved upright by walking motion

A team of anthropologists says it has solved a longstanding puzzle about how the people of Rapa Nui moved the island's massive moai statues: the monoliths were transported upright by a controlled rocking motion, effectively "walking" to their final positions along specially prepared roads. The conclusion, based on high-resolution 3D modeling, analysis of nearly 1,000 statues and field experiments, was published recently in the Journal of Archaeological Science by researchers from Binghamton University and the University of Arizona.

The researchers reconstructed the statues' shapes in detail and identified recurring features that would facilitate upright rocking: a wide D-shaped basal profile and a slight forward lean that shifts the center of gravity. To test whether such a form could be moved over distance, the team built a 4.35-ton replica moai and, with a crew of 18 people using ropes, walked it roughly 100 meters in 40 minutes by alternately pulling on either side to induce a zigzag rocking motion. Lead author Carl Lipo described the effort by saying, "Once you get it moving, it isn't hard at all... the hard part is getting it rocking in the first place."