Ecology of the collapse of Rapa Nui society.

M Lima,S A Estay,S Pla-Rabes,S Giralt,C M Santoro,A Sáez,O Margalef,N Chr Stenseth,N Cañellas-Boltà,C Latorre,E M Gayo

doi:10.1098/rspb.2020.0662

Abstract

Collapses of food producer societies are recurrent events in prehistory and have triggered a growing concern for identifying the underlying causes of convergences/divergences across cultures around the world. One of the most studied and used as a paradigmatic case is the population collapse of the Rapa Nui society. Here, we test different hypotheses about it by developing explicit population dynamic models that integrate feedbacks between climatic, demographic and ecological factors that underpinned the socio-cultural trajectory of these people. We evaluate our model outputs against a reconstruction of past population size based on archaeological radiocarbon dates from the island. The resulting estimated demographic declines of the Rapa Nui people are linked to the long-term effects of climate change on the island's carrying capacity and, in turn, on the ‘per-capita food supply’.

Highlights

Prehistoric producer societies provide unique socio-ecological laboratories for understanding the relationship between human population, food production and climate variability, with profound implications for current sustainability problems [1]
By combining independent sources of palaeoclimate, palaeoecological and palaeodemographic data, we argue that the use of the theory of population dynamics (TPD) framework represents an important advance in understanding the population dynamics of Rapa Nui people, and other prehistoric food producer societies
The summed probability densities (SPDs) values obtained for Rapa Nui suggest that human energy consumption was very low from 800 to 1100 CE, which is indicative of a stationary phase with reduced demographic pressures on the island or even no stable human colonization

Summary

Introduction

Prehistoric producer societies provide unique socio-ecological laboratories for understanding the relationship between human population, food production and climate variability, with profound implications for current sustainability problems [1]. A number of studies covering the Holocene period have used the summed probability densities (SPDs) of archaeological radiocarbon dates to infer demographic changes of food producer human societies and their potential connections to large-scale climatic processes [2,3,4], as well as to develop and test scenarios for implementing land-use and land-cover changes [5]. In most of these studies, the relationship between human population dynamics and past climate fluctuations is evident.

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Conclusion