Diet of the Prehistoric Population of Rapa Nui (Easter Island, Chile) Shows Environmental Adaptation and Resilience

Abstract

Objectives: The Rapa Nui "ecocide" narrative questions whether the prehistoric population caused an avoidable ecological disaster through rapid deforestation and over-exploitation of natural resources. The objective of this study was to characterize prehistoric human diets to shed light on human adaptability and land use in an island environment with limited resources. Materials and methods:Materials for this study included human, faunal, and botanical remains from the archaeological sites Anakena and Ahu Tepeu on Rapa Nui, dating from c. 1400 AD to the historic period, and modern reference material. We used bulk carbon and nitrogen isotope analyses and amino acid compound specific isotope analyses (AA-CSIA) of collagen isolated from prehistoric human and faunal bone, to assess the use of marine versus terrestrial resources and to investigate the underlying baseline values. Similar isotope analyses of archaeological and modern botanical and marine samples were used to characterize the local environment.Results: Results of carbon and nitrogen AA-CSIA independently show that around half the protein in diets from the humans measured came from marine sources; markedly higher than previous estimates. We also observed higher d | I N T R O D U C T I O NRapa Nui (Easter Island, Chile) is frequently used as an exemplar of human social competition and an avoidable ecological disaster, in which rapid destruction of the native palm forest had devastating consequences for the island's environment and human population (e.g., Diamond, 2005). Recent archaeological research has brought such Malthusian claims into question: the arrival of the Pacific rat (Rattus exulans) shortly after the island's colonization may have extensively contributed to the palm forest's demise (Hunt, 2007) and with the use of fire the island was transformed into an agricultural landscape (Hunt & Lipo, 2006).Revised chronologies indicate settlement of Rapa Nui centuries later than previously supposed, with evidence for a more balanced use of the environment and a greater degree of human adaptability to a changing ecosystem than the "ecocide" model purports (Hunt & Lipo, 2006;Stevenson et al., 2015). Knowing past diets is crucial for understanding the impacts of human occupation on Rapa Nui. Despite the intrinsic connection between human behavior and the utilization of natural resources in this small and ecologically-constrained island environment, prehistoric diets of the native islanders are still debated and poorly understood. Dietary evidence is spatially and temporally scattered, and its quality is affected by unfavorable preservation and taphonomic transformations; thus diet has been inferred from stable isotopic compositions.Rapa Nui is a small (171 km 2 ), remote volcanic island located in the south-eastern Pacific initially colonized in the early 13 th century AD (Hunt & Lipo, 2006). Polynesian settlers introduced chicken (Gallus gallus) and the Pacific rat, but the island has no endemic mammals or land birds (Klemmer & Zizka, 1993). Int...