Diet of the prehistoric population of Rapa Nui (Easter Island, Chile) shows environmental adaptation and resilience

Abstract

ObjectivesThe 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 methodsMaterials 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.ResultsResults 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 δ15N values in human collagen than could be expected from the local environment.DiscussionOur results suggest highly elevated δ15N values could only have come from consumption of crops grown in substantially manipulated soils. These findings strongly suggest that the prehistoric population adapted and exhibited astute environmental awareness in a harsh environment with nutrient poor soils. Our results also have implications for evaluating marine reservoir corrections of radiocarbon dates.

Complexities of Stable Carbon and Nitrogen Isotope Biogeochemistry in Ancient Freshwater Ecosystems: Implications for the Study of Past Subsistence and Environmental Change

“…From an archaeological perspective, particularly where data are derived from smaller sample sets and where paleoenvironmental data for past nutrient dynamics are unknown, it is important to approach interpretations of δ 15 N values in the context of use of freshwater resources with caution. In this context, ongoing advances in CSIA-AA could provide additional information to help distinguish between different nitrogen sources in ancient ecosystems (Jarman et al, 2017). For instance, studies comparing AA δ 15 N values can help assess the relative importance allochthonous vs. autochthonous inputs for aquatic consumers' diets (Ishikawa, 2018).…”

Amino acid δ13C and δ15N from sclerotized beaks: a new tool to investigate the foraging ecology of cephalopods, including giant and colossal squids

“…(2) Within that context, it is notable that most animal isotopic studies are based on bulk analysis, a few on d 15 N CSIA-AA, a very few on d 13 C CSIA-AA and almost none on both d 13 C and d 15 N CSIA-AA (but see Petzke et al 2005, Jarman et al 2017, Pomerleau et al 2017. The present work underlines that the isotopic me thod is at its best when including concomitant measurements of bulk and AA d 13 C and d 15 N analyses on the same samples.…”

CLAFS, a Holistic Climatic-Ecological-Anthropogenic Hypothesis on Easter Island's Deforestation and Cultural Change: Proposals and Testing Prospects

“…In this scenario, the timing of deforestation does not differ considerably from that of the ecocide hypothesis. Regardless of the ultimate cause of deforestation, a number of researchers dismiss the occurrence of social crisis following forest clearing and argue that the Rapanui were resilient to forest removal and remained healthy until European contact Boersema, 2015;Jarman et al, 2017). Analysis of widespread land-use evidence and radiocarbon dates from archeological sites across the island support this hypothesis and suggest that the ancient Rapanui developed sustainable agricultural practices and did not experience a social crisis prior to Europen arrival (Stevenson and Haoa-Cardinali, 2008;Mulrooney, 2013;Stevenson et al, 2015).…”