Natural and anthropogenic drivers of cultural change on Easter Island: Review and new insights

Abstract

Easter Island (Rapa Nui) is a remote Pacific island known for its megalithic statues, the moai, built by an ancient culture which disappearance is still debated. Theories claiming for either self-destruction (ecocide) of this ancient culture or an eventual genocide after the European contact have been the most popular. Anthropogenic drivers have been traditionally preferred as causes of this major cultural shift, whereas climatic changes have been dismissed or underrated. However, the latest findings suggest that the topic is more complex than formerly thought and demand a more holistic perspective. This paper reviews the main paleoclimatic, paleoecological, archaeological and historical evidence of the major Rapanui cultural shift leading to the end of the moai-building civilization and uses an integrated approach to analyze its timing and potential causes. The disappearance of the ancient Eastern Island culture that erected the moai was a dramatic cultural shift with significant changes in lifestyle, sociopolitical organization, religious performance, art and also in the geographical settlement of the cultural core of the Rapanui society. The ancient society, represented by the so called Ancient Cult (or moai cult) was centered on the Rano Raraku crater, to the east of the island, whose soft volcanic rocks (tuff) where suitable for moai carving. This society was replaced by the Birdman-Cult society, based on Rano Kao, to the westernmost end of the island. The assumed date for such shift is uncertain ranging between mid-16 th and late-18 th centuries. It is suggested that such geographical change, as well as the associated societal transformations, may have been the result of a combination of climatic, ecological and cultural drivers and events. The latest paleoecological reconstructions show that the Rano Raraku catchment was deforested by AD 1450 and the lake inside dried out by AD 1550 owing to an intense climatic drought. This would have caused a landscape deterioration transforming the Raraku catchment into a wasteland devoid of freshwater and unsuitable for human life and the cultural flourishment that characterized the Ancient-Cult society. The drought lasted for about 3 a century and a half and would have forced the Rapanuis to look for alternative freshwater sources. The only feasible option was the freshwater lake inside the then forested Rano Kao crater, where the ceremonial village of Orongo, the center of the Birdman Cult, was funded by AD 1600. The Kao crater is made of hard volcanic rocks (basalts) unsuitable for moai carving by the Neolithic Rapanui culture, unaware of metals, which would have contributed to the end of the moai-building phase. Deforestation and drought would have led to a general demographic decline. The shift from the rigid socio-political organization of the Ancient Cult to the more flexible system characteristic of the Birdman Cult could be viewed as a cultural adaptation to changing environmental conditions. The occurrence of a further, rather catastrophic, genocide caused by...

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

“…The transition from Ancient Cult to Birdman Cult occurred shortly after the onset of the LIA drought (1,570-1,720 CE), suggesting a novel hypothesis for the cultural change and the corresponding geographical displacement of the Rapanui cultural core (Rull, 2016a). During this drought, Rano Raraku was a very inhospitable place devoid of forests and freshwater due to the synergistic action of climatic drought and unsustainable human practices.…”

“…The first encompassed most of the Medieval Climate Anomaly (MCA) and the second occurred during the LIA (Rull et al, 2016), supporting the initial proposal of McCall (1993), that there is a connection between climatic severity and Rapanui societal changes. However, the link between environmental and cultural shifts remained unclear (Rull, 2016a). Palynological analysis of the Raraku and Aroi continuous sequences provided more information in this regard.…”

“…In this context, it has been speculated that a more flexible sociopolitical organization would have increased human adaptability to less predictable environmental and probably unprecedented conditions. The shift from the AC rigid, hierarchical and dynastybased political system to the more dynamic BC system, based on the continuous political renovation has been interpreted in terms of cultural adaptation to more unpredictable environmental conditions (Rull, 2016a).…”

“…In this paper, we introduce the first continuous and coherent sequence from Rano Kao encompassing the last millennium and discuss the potential significance of its paleoecological analysis, which is in progress, for testing previous and novel hypotheses about deforestation in relation to eventual climate changes and/or cultural developments (Rull, 2016a). This Kao sequence will complement the aforementioned Aroi and Raraku records of the last millennia to provide an island-wide history, capable of resolving spatio-temporal trends and patterns of deforestation, as well as addressing questions concerning human occupation and eventual intra-island migrations.…”

Human occupation and ecosystem change on Upolu (Samoa) during the Holocene

“…The gradual nature of the suggested landscape opening on Upolu indicates an incremental human impact that mirrors trajectories of change observed on Fiji (Roos, Field, & Dudgeon, 2016), but is in contrast to abrupt impacts recorded in Rapa Nui (Flenley & King, 1984;Rull, 2016). It is likely that, in all situations, the ratio between the human population size and the amount of available land and coastal areas plays an important role on the degree of impact.…”