GPS World, February 2019

RESEARCH Roundup R apa Nui Easter Island Chile is famous for its elaborate ritual architecture more than 300 monumental platforms ahu and nearly 1000 monumental multi ton anthropomorphic statues moai To date however we lack explicit modeling to explain spatial and temporal aspects of monument construction In a span of only about 500 years from the 13th century A D to European contact in A D 1722 and into historic times the Rapanui islanders sculpted and erected these famous megalithic statues Why And why were they placed where they stand For many years scholars thought that the island must have supported a larger and more complex society under more prosperous environmental conditions that then collapsed following a self imposed ecocide In recent years nearly every major component of this narrative has been shown to lack empirical sufficiency In this paper we use spatially explicit point process modeling to explore the potential relations between ahu construction locations and subsistence resources namely rock mulch agricultural gardens marine resources and freshwater sources the three most critical resources on Rapa Nui Through these analyses we demonstrate the central importance of coastal freshwater seeps Our results suggest that ahu locations are most parsimoniously explained by distance from freshwater sources in particular coastal seeps with important implications for community formation and inter community competition in precontact times The islands marginal ecology limited the food options available to the inhabitants These environmental constraints could be a key factor in the emergence of monuments on Rapa 42 GPS WORLD WWW GPSWORLD COM FEBRUARY 2019 Nui such as their role as adaptive responses to environmental uncertainty or as territorial signals of control over limited resources We quantitatively modeled how the spatial distribution of ahu is explained by different resources thought to be the focus of competition Point process models PPM are a wide class of spatially explicit models that facilitate formal analysis of the relationship Images Robert DiNapoli and co authors Figure 1 Locations of image ahu on Rapa Nui Easter Island Figure 2 Locations of freshwater sources POINT PROCESS MAPPING LINKS EASTER ISLAND STATUARY TO FRESHWATER SOURCES BY Robert DiNapoli University of Oregon Carl Lipo Binghampton University Tanya Brosnan and Matthew Becker California State University Long Beach Terry Hunt University of Arizona Sean Hixon Pennsylvania State University Alex E Morrison University of Auckland See Easter Island page 45