The colossal hats (pukao) of monumental statues on Rapa Nui (Easter Island, Chile): Analyses of pukao variability, transport, and emplacement

The archaeological record of Rapa Nui (Easter Island, Chile) is noteworthy for its massive statues (moai) that were transported over long distances with relatively small numbers of people and minimal use of resources. Equally impressive are the colossal bodies of red scoria (pukao) placed on the heads of many of the moai. In this study, we use three-dimensional models of 50 pukao found across the island and 13 red scoria cylinders from Puna Pau, the island's pukao quarry, to study the process of pukao manufacture, transport, and placement atop statues. Our analysis identifies surface features that are explained by the process of construction and transport of these multi-ton objects. Based on shared physical features of pukao, evidence in the archaeological record, and the physics necessary for pukao movement, we propose a falsifiable hypothesis in which relatively small numbers of people rolled pukao up stone ramps to place pukao atop moai. We conclude that activities of pukao production and transport did not require oversight by a centralized political authority, nor do they support notions of a large population that collapsed with “ecological suicide” on Rapa Nui.