Introduction

Abstract

The ancient and still enigmatic Polynesian society that lived in Rapa Nui (Easter Island) before European contact (1722 CE, common era) has fascinated scientific and popular audiences for generations. The remoteness of the island and its intermediate position between Polynesia, to the west, and South America, to the east (Fig. 1.1), has boosted the debate between the time of settlement and the origin of the first settlers. Although the aboriginal and the modern cultures are clearly of Polynesian origin, the possible influence of Amerindian (or Native American) cultures has been suggested throughout history. The better-known advocate of an Amerindian origin for the first colonizers was the Norwegian explorer Thor Heyerdahl, who organized the famous Kon-Tiki expedition that, in 1947, navigated from the Peruvian coast to the Tuamotu Islands (Fig. 1.1) using a wooden raft propelled only by wind and marine currents (Heyerdahl 1952). For Heyerdahl, this demonstrated that Native Americans could have arrived to Easter Island with their rudimentary navigation technology. Some years later, Heyerdahl led an expedition to Rapa Nui and supported his idea by survey and excavation of the abundant archaeological remains that, according to the explorer, were mostly of Amerindian origin (Heyerdahl and Ferdon 1961). Heyerdahl’s beliefs were first accepted but strongly opposed after reanalysis of the available evidence (Flenley and Bahn 2003). The spectacular development of molecular genetic analytical techniques during the last decades reopened the debate, which is still ongoing (Thorsby 2016). The time of discovery and first settlement of the island also remains a mystery, as different authors situate these events between 400 CE and 1300 CE (Kirch 2010; Wilmshurst et al. 2011; Flenley and Butler 2018; Hunt and Lipo 2018).

1 The Enigmas of Rapa Nui

The ancient and still enigmatic Polynesian society that lived in Rapa Nui (Easter Island) before European contact (1722 CE, common era) has fascinated scientific and popular audiences for generations. The remoteness of the island and its intermediate position between Polynesia, to the west, and South America, to the east (Fig. 1.1), has boosted the debate between the time of settlement and the origin of the first settlers. Although the aboriginal and the modern cultures are clearly of Polynesian origin, the possible influence of Amerindian (or Native American) cultures has been suggested throughout history. The better-known advocate of an Amerindian origin for the first colonizers was the Norwegian explorer Thor Heyerdahl, who organized the famous Kon-Tiki expedition that, in 1947, navigated from the Peruvian coast to the Tuamotu Islands (Fig. 1.1) using a wooden raft propelled only by wind and marine currents (Heyerdahl 1952). For Heyerdahl, this demonstrated that Native Americans could have arrived to Easter Island with their rudimentary navigation technology. Some years later, Heyerdahl led an expedition to Rapa Nui and supported his idea by survey and excavation of the abundant archaeological remains that, according to the explorer, were mostly of Amerindian origin (Heyerdahl and Ferdon 1961). Heyerdahl’s beliefs were first accepted but strongly opposed after reanalysis of the available evidence (Flenley and Bahn 2003). The spectacular development of molecular genetic analytical techniques during the last decades reopened the debate, which is still ongoing (Thorsby 2016). The time of discovery and first settlement of the island also remains a mystery, as different authors situate these events between 400 CE and 1300 CE (Kirch 2010; Wilmshurst et al. 2011; Flenley and Butler 2018; Hunt and Lipo 2018).

Fig. 1.1

The Pacific Ocean and its main archipelagos. Rapa Nui is represented by a red dot and the distances, in km, to the nearest Polynesian and American archipelagos are indicated. Modified from Rull (2020)

The most iconic manifestations of the ancient Rapanui culture are the nearly 1000 megalithic statues known as moai (Van Tilburg 1994) (Fig. 1.2). The main enigmas surrounding these monuments deal with their construction, transportation, and cultural meaning. The first European explorers wondered how the relatively small Rapanui population they encountered could have carved, transported, and erected these giant sculptures without resources such as wood (the island was deforested by the time of European contact), metals, and the associated technology (Fischer 2005). Today, it is known that the moai were carved on soft rock (tuff) using harder tools made of basalt, and that these statues represented deified ancestors like former clan chiefs, whose worship was intended for fertility and prosperity (Edwards and Edwards 2013). However, the technology used to transport these megalithic statues and emplace them on their altars (ahu) remains speculative. Several transportation techniques have been proposed and some of them have been tested in the field using moai reproductions, wood, ropes, and a significant number of people (Hunt and Lipo 2011). However, all these methods are imaginative procedures based on present-day ingenuity and the lack of irrefutable archaeological evidence, drawings, and written documents prevents demonstrating what was the actual means of moai transportation and emplacement. Beyond the moai, there are many other archaeological remains all over the island totaling about 20,000 stone features that are still preserved in their original location (Vargas et al. 2006). This is why the American archaeologist William Mulloy, who was part of the abovementioned Heyerdahl’s expedition to the island, considered Rapa Nui as “the most spectacular potential outdoor museum to be found anywhere in Polynesia” (Mulloy 1974).

Fig. 1.2

Left: Some examples of moai on their respective ahu (Photos: V. Rull and N. Cañellas-Boltà). Right: Size comparisons of the biggest moai with an average human

Easter Island is also famous for the internal cultural collapse of the pre-contact Rapanui society that erected the moai. It was Mulloy (1974) who launched the idea that at initial settlement the island was covered by a dense forest. After arrival the forest was totally cleared by the Rapanui settlers who used the wood and other plant parts for construction and moai transportation. According to this author, this was one more manifestation of the general overexploitation of the island, which ended with the depletion of many natural resources and the ensuing demise (in demographic and cultural terms) of the Rapanui society. Further palaeoecological studies developed by the British palynologist John Flenley and his coworkers demonstrated that, indeed, the island was covered by dense palm-dominated forests for more than 30,000 years (Fig. 1.3), before its total disappearance during the last millennium (Flenley and King 1984; Flenley et al. 1991). The approximate chronological coincidence of the forest removal with the Polynesian settlement of Rapa Nui was used by these authors as evidence for Mulloy’s self-induced cultural collapse hypothesis—also called ecocide by some authors (Diamond 2005)—and presented as an example of what could be the future of the whole Earth if current overexploitation practices continued (Bahn and Flenley 1992). This ecocide hypothesis dominated the scientific and non-scientific scenes for decades and is still accepted by many researchers and popular media. However, recent archaeological and palaeoecological evidence challenges the collapse idea and supports the scenario that the Rapanui culture did not collapse but remained healthy and prosperous until European contact, even in the absence of a forest (Mulrooney 2013; Stevenson et al. 2015). As a consequence, the real collapse of the Rapanui culture occurred after European contact, in the 1860s–1870s, and was caused by slave raiding and the introduction of alien epidemic diseases such as syphilis, smallpox, or tuberculosis (Fischer 2005; Boersema 2015). Some authors have called this collapse a genocide (Peiser 2005).

Fig. 1.3

Comparison between a hypothetical reconstruction of former Rapa Nui’s palm forests (above) and the present landscape (below) on the Poike Peninsula. Images courtesy of Andreas Mieth

Whether the ancient Rapanui society suffered a demographic collapse, or was resilient to total island deforestation, this ecological shift initiated a profound change in the Rapanui culture that affected social, political, and religious aspects. The ancient religion, based on the ancestor worship and a strict hierarchical society with a dynastic successional system, was progressively replaced by the Birdman cult, where the maximum authority of the island (the Ariki Mau) was renewed every year from among the different clan chiefs (Routledge 1919; Métraux 1940; Englert 1948). The causes for this deep cultural change are still poorly understood although the defenders of the collapse hypothesis believe that the lack of wood and plant material prevented the continuity of the moai fabrication and megalithic architecture in general. At the same time, the onset of social conflicts, wars, and cannibalism, exacerbated by the lack of natural resources to maintain former population levels, could have determined a demographic collapse and a deep change in lifestyle (Bahn and Flenley 1992). Others suggest that, in a more resilient scenario, a territorial restructuring in response to soil nutrient depletion and a long period of dryness could have been involved (Robinson and Stevenson 2017). The chronology of this last episode of cultural change is also uncertain and ranges from the sixteenth century to after the European contact (Lee and Liller 1987; Pollard et al. 2010). The Birdman cult implied the development of a new symbology represented mainly by a widespread petroglyph industry, also called rock art, with more than 4000 petroglyphs (rona) still preserved (Lee 1992) (Fig. 1.4).

Fig. 1.4

Petroglyphs (rona) carved on basalt in the ceremonial site of Orongo, where the Birdman ceremony took place. Photo: V. Rull

Another controversial topic has been the potential influence of climatic changes in the prehistory of Rapa Nui. This possibility had not been considered until the palynological surveys of Flenley and his team, who suggested the possibility of climatic shifts during the last millennia but not of sufficient intensity to cause the observed vegetation changes, especially the total forest removal. These authors argued that if Easter Island’s forests had survived the pronounced and extended fluctuations in temperature and moisture balance that occurred between the Late Pleistocene and the Middle Holocene, including the Last Glacial Maximum, it would be unreasonable to assume that they could have been annihilated by the comparatively lower climatic variability of the Late Holocene (Bahn and Flenley 1992). Other authors suggested that global and quasi-global climatic changes such as the Medieval Warm Period (750–1250 CE) or the Little Ice Age (1350–1800 CE) could have had some influence on Easter Island’s ecological and cultural trends (McCall 1993; Nunn 2007). However, these proposals were speculative as no evidence of climate change existed for the island. The first direct evidence of local climatic change on the island emerged roughly a decade ago, when Mann et al. (2008), using palaeoecological evidence from lake sediments (Fig. 1.5), suggested the occurrence of a drought, or a succession of droughts, of approximately 3000 years, ending by 1200–1300 CE. The last decade has witnessed a significant increase of palaeoecological work on Rapa Nui, and the establishment of a preliminary palaeoclimatic chronology for the last millennia, in relation to ecological and cultural developments (Rull 2021).

Fig. 1.5

Lake Raraku, within the Rano Raraku crater. The sediments of this lake have been instrumental in deciphering palaeoecological trends on Rapa Nui. Photo: V. Rull

There are more mysteries and enigmas to solve in the prehistory of Rapa Nui but those summarized here may be considered the most notorious and widespread in both scientific and popular environments. Interested readers may increase their background by looking at the references cited, which constitute a representative selection of the existing literature.

2 Aims and Scope

The enigmas of the ancient Rapanui culture have been addressed from a variety of scientific disciplines, notably archaeology, anthropology, ethnography, history, and palaeoecology. These disciplines have traditionally progressed in isolation with little interaction among them. Occasionally, some authors have tried to integrate evidence from several fields of knowledge but the main handicaps are the bias towards ones own approach and the difficulty of evaluating the evidence from alien disciplines. Sometimes, discussions among the different disciplines have developed into personal attacks with explicit political connotations (e.g., Flenley and Bahn 2007a, b; Hunt and Lipo 2007), which is contrary to the spirit of scientific research. The time has come to reverse these bad procedures and address the scientific research on Easter Island from a constructive multidisciplinary approach.

Understanding Rapa Nui prehistory, where environmental, ecological, and cultural processes and mechanisms constantly interact, requires a synergistic approach among the different disciplines. Active transdisciplinary collaboration among researchers from disparate fields is needed to pave the way towards more general hypotheses that may lead to more holistic views of the Rapa Nui prehistory. Palaeoecology, archaeology, anthropology, ethnography, history, and related disciplines should be viewed as complementary rather than excluding sciences whose practitioners compete for an imaginary right, unique, and definitive evidence from their own fields. Each of these disciplines is part of the same puzzle and we should learn how to assemble it together instead of claiming the absolute truth using only our particular, always incomplete, set of pieces (Rull 2020).

Ideally, collaboration should begin with the formation of multidisciplinary research teams and the careful selection of interdisciplinary research methods, as well as the definition of a synthetic framework able to account for the complexity of the whole socioecological system. This is not an easy task and requires previous initiatives addressed to gather and analyze the existing interdisciplinary knowledge and to test and/or develop suitable synthetic frameworks. The main aim of this book is to take the first steps in that direction.

To achieve this, we did an extensive literature review and invited all researchers and research teams who are, or have been, actively working and publishing on Rapa Nui. No one was excluded. Almost a hundred researchers representing as many disciplines as possible were included in the list. As usual, a portion of these scholars never answered and others politely declined the invitation. About the half of the requested researchers agreed to contribute and the initial book proposal consisted of ca. 40 chapters. However, almost half of these promised manuscripts were never submitted, with or without an explanation. Only a couple of the submitted manuscripts were withdrawn during the review process, whose only aim was to improve the manuscripts (none were rejected). Finally, the book is now composed of 22 chapters (plus the Introduction and the final Synthesis), by 55 contributors (see the List of Contributors), organized thematically, rather than by discipline, as explained in the next section. We are aware that it is not usual to give these numbers but we consider that it is important to emphasize that the book was open to any contributor from any research field.

Obviously, the book is neither a thorough compilation of the existing knowledge about Rapa Nui prehistory nor an exhaustive update. However, the book contains representative samples of the latest studies developed on the island and the state of the art of the different disciplines. At the end of the book, a first attempt to synthesize the most relevant multidisciplinary knowledge into a holistic framework is presented using the information provided in the preceding chapters and the most relevant literature. We hope that this book may be useful to help developing truly multidisciplinary research on Easter Island. This is our contribution to the venture and now we rely on the constructive scientific attitude and the good faith of researchers working on Rapa Nui.

3 Book Organization

The book is subdivided into six main parts. The first part is entitled Transpacific voyaging and settlement and is composed of five chapters. Anderson (Chap. 2) starts off the book by considering a question raised over 150 years ago; was there contact between South America and Easter Island? A century of debate and investigation has not been able to resolve the details of interaction but the evidence is accumulating for a more direct involvement of persons from Peru. There are complex similarities in architectural features between the two regions such as tupa, birdman motifs, and the ahu Tahiri (ahu no. 1) at Vinapu, the latter which contains so many design similarities that the direct involvement of an Inkan craftsman is seen as highly probable. Now with the application of improved radiocarbon methods there is also a time convergence between the two cultures. But how did an Inkan craftsman get to Rapa Nui? Maybe by a balsa log raft, which was a well-developed and sturdy seafaring technology developed in southern Ecuador for which there is evidence of usage on the open ocean in the second millennium CE. Equipped with such a craft, the likelihood of the movement of people and ideas into Polynesia from the east becomes increasingly real.

In Chap. 3, Thompson et al. address the problem of Rapa Nui settlement using domesticate/commensal plant and animal species that the colonizers transported as resources to survive in the newly colonized land; a modification that also made the island a comfortable place to live and similar to their ancestral homeland. The clearest evidence of products coming from the west (Polynesia) are bananas, chickens, Pacific rat, paper mulberry, sugarcane, taro, and yams. However, the presence of sweet potato and bottle gourd may have been the result of later trade, including contact with South America. The translocation histories of these nine domesticate/commensal plants and animals are used by Thompson et al. to clarify the migration routes used by the early Rapa Nui colonizers.

Muñoz-Rodriguez et al. (Chap. 4) provide the reader with a botanical background to one of the most important crops on Rapa Nui, the sweet potato (Ipomoea batatas). Along with taro and yam, the sweet potato was the staple food and backbone of the Rapa Nui economy. The authors bring a critical eye to how the evidence for sweet potato in the Pacific region is evaluated. They have waded through large numbers of documents to find those with original evidence and then evaluate them to identify ambiguities that may result in the mis-identifications with other members of the genus Ipomoea, the morning glory. Methodological issues in the identification of macro specimens, pollen grains, and starch and shortcomings with these methods as applied to Rapa Nui are identified and the general conclusion is that “the utility of most archaeological remains to enable differentiation between cultivated sweet potato, non-cultivated sweet potato and other species of Ipomoea is unsatisfactory”. Despite these issues, human introduction of sweet potato that occurred around 1300 CE is supported, but caution must be exercized in making identifications.

Van Tilburg et al. (Chap. 5) present their discovery of the first directly dated and well-contextualized example of sweet potato on Rapa Nui from the excavation of moai 156/157 within the interior of the Rano Raraku statue quarry. Directly dated specimens of sweet potato are relatively few in the Pacific archaeological record and this example assists with the problem of origins. Equally important is the relevance of this and other dated specimens to the time range of agricultural activity within the quarry. Used in conjunction with 20 other radiocarbon dates on short-lived species the authors estimate the duration of agriculture within the crater interior. These data serve as a proxy for moai production at Rano Raraku.

Wallin and Martinsson-Wallin (Chap. 6) reconsider their 1987–1988 results from the excavations at ahu Nau Nau and focus on an area which they call ahu Nau Nau East located about 50 m to the north. After the initial excavations, the sector was interpreted as an associated ritual area attached to the main ahu, but redating of the space show it to be in line with the earlier initial settlement phase of Rapa Nui. Located beneath the deep beach sands was an artefact rich cultural layer with refuse pits containing food remains, postmolds, a stone alignment, fire pits, and a small vertically-set stone figurine. Taken together the area is interpreted as an early ritual space, possibly partitioned by a fence (the alignment) behind which feasting and sacrifice may have taken place. This early, and unique, ritual area is soon to be replaced by construction of megalithic architecture so characteristic of Rapa Nui.

The second part of the book is entitled The ancient Rapanui culture and is composed of four chapters. Stevenson et al. (Chap. 7) offer a new interpretation for the archaeological feature known as the refuge cave or ana kionga. Initially identified by explorer La Perouse in 1786, this type of cave with a narrow tunnel entrance was a major piece of supportive evidence for the collapse theory as it was seen as an archaeological correlate for internal warfare. Detailed excavations reveal that not only the entrance, but the interior, is architecturally modified and contains prepared clay floors and platforms. The extent of modification suggests to the authors that the cave is not a refuge from violence, but rather, a prepared ritual space possibly connected with the Birdman cult. Accelerator mass spectrometry (AMS) radiocarbon and obsidian hydration dates put peak usage in the early 1800s CE but the exact beginning of cave modification and use is still unclear.

Martinsson-Wallin (Chap. 8) takes us to one of the most impressive ceremonial places on Rapa Nui, that of the ahu Vinapu complex. It was one of the first locations investigated on Rapa Nui by archaeologist William T. Mulloy. The architectural interpretation of Mulloy is reviewed in detail for two ahu and the two adjacent elite house complexes. This sets the context for the chapter which is to evaluate the early twelfth century radiocarbon date (M-710 BP 1100 ± 200) from underneath the earthwork embankment that surrounds the plaza of ahu No. 2. New AMS radiocarbon dates on nutshell from two contexts returned dates of 1304–1437 CE and 1303–1442 CE (2σ) and demonstrate a later date for ceremonial activities in this area than previously thought.

Cauwe and De Drapper (Chap. 9) address a long-held interpretation about the isolated moai that are found along the network of roads leading away from the statue quarry of Rano Raraku. Conventionally, these fallen, and sometimes broken, statues are interpreted to be accidents of transport and abandonment but two forms of evidence suggest otherwise. Morphologically the moai “in transport” are different in proportions than those present at ahu which raises the question of whether installation on an ahu was indeed the end goal. They also expand upon an observation made by Katherine Routledge in the early twentieth century that identified moai surface erosion patterns (runnels) which could only form if the statue was positioned vertically for an extended period. Taken together, this evidence suggests that the statues marked the road, possibly to help ensure safe travel of other moai to their platforms.

Cauwe (Chap. 10) tackles another theme of the Rapa Nui collapse scenario, that of the violent destruction of the ahu and toppling of the moai. Fallen statues and rock-covered ahu give the modern viewer a sense of disarticulation that is hypothesized to come from a society gripped by self-destruction. But nothing could be further from the truth. The author lays out a convincing case for ahu construction and ritual closure identified from his excavations. Closure is marked by the removal of sea cobbles from the structure and the applications of granular red scoria, and after a period, the ahu is rebuilt anew. Thus, each ahu has its own unique multi-phased life history. This activity of ritual closure extends to the final phase of prehistory where the moai are lowered and the entire structure covered with basalt field stone; never to be rebuilt again.

The third part of the book is entitled Climatic and environmental change and is composed of three chapters. Bradley et al. (Chap. 11) inaugurate this part by providing insights on the present Rapa Nui climate using instrumental data from a meteorological station situated at the airport (Mataveri). Emphasis is on rainfall amount and regime. Climatically, the island is under the influence of the Sub-Tropical High Pressure Zone (STHPZ) and the South Pacific Convergence Zone (SPCZ), with no significant long-term correlation between rainfall and the phase of the El Niño Southern Oscillation (ENSO) or the Pacific Decadal Oscillation (PDO). Daily rainfall amounts rarely exceed 100 mm and occur on about half of the days. Moisture sources are similar in both wet and dry years, and wet years result simply from the occurrence of more rainy days due to local synoptic conditions. During the last decade, rainfall has been well below the long-term average, which has significantly reduced the Rano Raraku lake to a small area of surface water. This is preliminary attributed to and expansion of the Warm Pool in the western Pacific, which has reduced rainfall east of the SPCZ.

Rull (Chap. 12) reviews the history of palaeoecological research on Rapa Nui and places the main findings in chronological context with the goal of realizing a more inclusive scientific framework for Easter Island prehistory. The discussion highlights climatic and ecological changes over the last millennium and the influences these factors may have had on sociocultural trends and events. Three main phases of palaeoecological research are recognized and include: the pioneer phase (1977–1992), the intermediate phase (1993–2004), and the revival phase (2005–present). The contribution of palaeoecology to developing a better understanding of Easter Island’s prehistory is discussed with a focus on four main points: (1) the discovery and settlement of the island, (2) the occurrence of climatic changes and their natural and anthropogenic drivers, (3) spatiotemporal deforestation patterns, and (4) the potential relationship between climatic, ecological, and cultural shifts. Future research avenues are suggested that would make Rapa Nui research a more holistic scientific endeavour.

Sáez et al. (Chap. 13) describe the main geological features of Rapa Nui and their influence on human occupation and habitation. The petrological characteristics and age of the volcanic rocks forming the island have greatly conditioned not just the geomorphological and edaphic processes but also the raw materials used by humans for construction. The lithology has been fundamental in shaping the island’s hydrology and water quality, which has had a great influence on human life and crop development. The sedimentary record of lakes and wetlands has uncovered climate changes that have significantly influenced deforestation. These authors also suggest that the occurrence of high-energy events such as tsunamis and long-distance volcanic eruptions may have influenced the island during the last millennium. They conclude that geological processes greatly influenced human settlement on Rapa Nui.

The fourth part of the book is entitled Deforestation and extinctions and is composed of five chapters. In Chap. 14, Zizka and Zizka compare the present flora and vegetation of Rapa Nui with the conditions before human arrival. They observed that the extant flora is dominated by alien species, most of which were introduced after European contact. The past flora, dominated by the Paschalococos disperta and the toromiro (Sophora toromiro) went extinct after human arrival. Under these conditions, reconstruction of the native flora and understanding its geographical origin is challenging. An updated list of potentially native species of flowering plants is provided, based on inventories, palynological records, and archaeological surveys from the literature. This list is then combined with information on potential native species from other plant groups (fern & allies, mosses, and liverworts), and the present-day geographical distribution of all these plants is used to infer geographic affinities for Rapa Nui’s native flora.

Ingersoll et al. (Chap. 15) examine the potential implications of palm morphological and anatomical features (as compared to dicotyledon trees) in archaeological interpretation, especially for dendrochronology and radiocarbon dating. In the case of Rapa Nui, these authors evaluate the potential role of the extinct palm Paschalococos disperta (related to the arecoid palms Jubaea, Cocos, and Roystonea) in relation to cultural uses such as canoe building, moai transport, and raw material for construction.

In Chap. 16, Steiglechner and Merico use mathematical models to evaluate important aspects of the pre-contact Rapanui culture such as the maximum size of human populations and the spatiotemporal deforestation dynamics. The main handicap of previous models was the lack of consideration for human decision-making and environmental heterogeneities. These authors introduce age-based models that consider these elements, as well as their interactions. Results indicate that patterns of deforestation, settlement, and land use vary from region to region, not only according to environmental heterogeneities but also human decisions, as for example moving from one area to another. This suggests that Rapa Nui prehistory is complex and cannot be captured by simple island-wide narratives.

Brander (Chap. 17) presents an economic and ecological model (EEM) of the interaction between the indigenous palm forest and the Rapa Nui population prior to first European contact. The model, which is a revision and reconceptualization of the problem published in 1998 by the same author, seeks to explain the pattern of deforestation over time and how it correlates with demographic trends. To mathematically model the functional relationships between variables of the forest, the people, and the economy, the data on each component is reviewed and the parameters and assumptions behind the simulation are developed. A simulation base case is run and it shows the expected boom-and-bust relationships between declining forest resources, population size, and per capita utility. Then, key parameters are varied to produce four alternative outcomes which highlight the relative importance of each variable. The best available evidence to date produces a weaker version of the catastrophe model where the population stabilizes at a relatively low level at the point of European contact.

In Chap. 18, Wozniak conducts detailed archaeological and geomorphological studies in Te Niu, on the northwest coast of Rapa Nui, to document a significant landscape change consisting of the long-term conversion of a palm-dominated forest to a food-production area. Archaeological excavations and dating (radiocarbon and obsidian hydration dates) provided evidence of the transformation of the original forests to gardens after 1300 CE and to grazing lands in the late nineteenth century. Geomorphological and hydrological evidence indicates that these transformations resulted in repeated erosion/sedimentation episodes. The shift from forest to croplands occurred after Polynesian settlement and the shift to grasslands took place after European contact, when the island was transformed into a ranch for imported sheep.

The fifth part of the book is entitled Collapse or resilience? and is composed of four chapters. Mieth et al. (Chap. 19) present a summary and interpretation of their extensive excavations at Ava Ranga Uka a Toroke Hau, located on the upper slopes of Maunga Terevaka. This complex of features consists of an ahu platform and moai, monumental terraces, elaborate water basins, canals, and superimposed stone pavements that straddle the upper reaches of the seasonal stream known as Quebrada Vaipú. Water was the focal point for this site but it was not directed into agricultural fields. Domestic settlements are rare and everyday access to the larger Rapa Nui population is inferred to have been restricted. The emphasis seems to have been on the preparation and use of a ritual space for fertility rituals where women may have been bathed during the birthing process. The complex stratigraphy of the complex suggests periods of ritual closing and refurbishment characteristic of other large-scale architecture. Radiocarbon dating places the use of the complex at c. 1270–1670 CE which was terminated when a catastrophic flood event tore through the sequence of superimposed pavements and covered the large-scale pigment production fields located just below the ritual complex.

In Chap. 20, Puleston and Ladefoged present two population models based on the idea of carrying capacity to estimate the maximum number of people who might be fed in a given place with a given agricultural and technological toolkit. Then, they apply these models to Rapa Nui in the period before European contact. The first model considers surplus production beyond subsistence requirements and work load. The second model is more dynamic and adjusts demographic rates in response to food availability, eventually approaching an equilibrium. The application of these models to prehistoric Rapa Nui is constrained by the uncertainty about the productivity of the island’s agricultural system, which yields a wide range of possible population estimates. The predicted population sizes that are consistent with archaeological evidence result from model runs using low production rates.

Lima et al. (Chap. 21) develop a model based on the population dynamic theory (PDT) that integrates climatic, demographic, and ecological factors. In Rapa Nui, the model predicts sustained population growth between 1100 CE and 1400 CE, followed by further demographic declines. These results are consistent with variations in the El Niño Southern Oscillation (ENSO) activity, especially droughts, which modulates island’s carrying capacity. Rapa Nui is viewed as a small and isolated island inhabited by an agrarian society facing resource scarcity, overpopulation, and climatic change. The suitability of PDT models to test predictions and explanations in such a situation is highlighted.

Lipo et al. (Chap. 22) look at the evidence that supports claims for large pre-European population size on Rapa Nui. When early navigators disembarked on Rapa Nui the number of persons was repeatedly estimated in the low thousands and visitors saw this as incompatible with the visible architecture. It was inferred that some catastrophic event had happened in the past to reduce population size. This reasoning has continued within modern archaeological research and the speculative estimates of pre-contact populations range between 7000 and 25,000 persons. The authors review the methods used to arrive at these population estimates such as house counts, resource abundance, and relative population size, and find the evidence lacking. They urge researchers to develop stronger measures for estimating population size in future research.

The sixth part of the book is entitled European contact and is composed of a single chapter. Boersema (Chap. 23) discusses two lesser-known accounts of a visit to Easter Island by the Dutch expedition led by Roggeveen in 1722. The writings appeared in 1727 and 1728 but have not been translated from the Dutch until now. Upon inspection, the accounts describe some of the same events as in the narrative of Roggeveen but differ significantly in the description of Rapanui women and men which are reported to be 10 and 12 ft in height. The question then becomes why did these exaggerations occur, why do people believe them, and is there a rational behind them? Psychologists believe there is an explanation and experimental studies show that a cultural bias heavily influences how factual information is interpreted by the observer. For example, in the eighteenth century, Europe giants are a part of Christian theology and this has an influential role in the eighteenth century observations where the citing of giants was not infrequent. This concept of word view and its influence on scientific thought is then discussed in relation to contemporary thinking about Rapa Nui prehistory.

The book is closed by a synthesis (Part 7; Chap. 24), written by the editors, aimed at progressing towards a holistic view of the island’s prehistory that considers as many disciplines as possible. This synthetic chapter adopts a human ecodynamics approach where the functional unit is the socioecosystem, which is composed of three subsystems (environment, landscape, and humans) and their corresponding feedbacks and synergies (EHLFS system). Human behaviour in relation to the EHLFS dynamics has a special component characterized by creativity and decision-making, which is not present in other subsystems, and is analyzed here in terms of niche construction. Using these approaches, the prehistory of Rapa Nui and the first stages of European contact (ca. 800 CE to ca. 1800 CE) are subdivided into six states of the sociecosystem (EHLFS1 to EHLF6), which are described and characterized in terms of environmental–ecological–human complexity.