A model-based approach to the tempo of “collapse”: The case of Rapa Nui (Easter Island)

Abstract

Rapa Nui (Easter Island, Chile) presents a quintessential case where the tempo of investment in monumentality is central to debates regarding societal collapse, with the common narrative positing that statue platform (ahu) construction ceased sometime around AD 1600 following an ecological, cultural, and demographic catastrophe. This narrative remains especially popular in fields outside archaeology that treat collapse as historical fact and use Rapa Nui as a model for collapse more generally. Resolving the tempo of "collapse" events, however, is often fraught with ambiguity given a lack of formal modeling, uncritical use of radiocarbon estimates, and inattention to information embedded in stratigraphic features. Here, we use a Bayesian model-based approach to examine the tempo of events associated with arguments about collapse on Rapa Nui. We integrate radiocarbon dates, relative architectural stratigraphy, and ethnohistoric accounts to quantify the onset, rate, and end of monument construction as a means of testing the collapse hypothesis. We demonstrate that ahu construction began soon after colonization and increased rapidly, sometime between the early-14th and mid-15th centuries AD, with a steady rate of construction events that continued beyond European contact in 1722. Our results demonstrate a lack of evidence for a pre-contact 'collapse' and instead offer strong support for a new emerging model of resilient communities that continued their long-term traditions despite the impacts of European arrival. Methodologically, our model-based approach to testing hypotheses regarding the chronology of collapse can be extended to other case studies around the world where similar debates remain difficult to resolve.

Tempo and Trajectory of the Built Landscape on Ta‘ū Island, Manu‘a Group, American Sāmoa: Integrating Extensive Radiocarbon Dating With Joint Posterior Modeling

“…Fortunately, the results of Bayesian calibration for each architectural feature can be input into software to model the joint posterior distributions of feature construction (Dye 2016;Marsh et al 2017;Banks et al 2019;DiNapoli et al 2020). The calculation of joint posterior distributions aims to assess the number of events that have occurred before some date by querying valid chronological estimates of feature construction that are produced through MCMC (Markov chain Monte Carlo) routines at the heart of Bayesian calibration.…”

Prehistoric pigment production on Rapa Nui (Easter Island), c. AD 1200–1650: New insights from Vaipú and Poike based on phytoliths, diatoms and 14C dating

“…Archaeological evidence points to the arrival of the first Polynesians on Rapa Nui somewhere between AD 800 and 1300 (DiNapoli et al, 2020; Flenley and Bahn, 2003; Hunt and Lipo, 2006; Wilmshurst et al, 2011), while possible earlier arrival is still under discussion (e.g. Cañellas-Boltà et al, 2013).…”

“…continued human activity (e.g. Boersema and Huele, 2019; DiNapoli et al, 2020; Hunt and Lipo, 2013; Mieth and Bork, 2015; Mulrooney et al, 2010). This is indicated for example by the presence and continued erection and use of monumental structures and the remains of labour-intensive stone gardening (lithic mulching) in terrain cleared of vegetation over as much as 45% of the island’s surface, i.e.…”

Population structure drives cultural diversity in finite populations: A hypothesis for localized community patterns on Rapa Nui (Easter Island, Chile)

“…Rapa Nui is a small (164 km 2 ) and remote island in the easternmost South Pacific (Fig 1) that was colonized by Polynesian voyagers in the 12th-13th Century AD [1][2][3][4]. The island is perhaps best known for the hundreds of multi-ton stone statues (moai) that the islanders constructed and transported over volcanic terrain to every part of the island and placed atop massive stone platforms (ahu) [5][6][7].…”