Many researchers believe that prehistoric Rapa Nui society collapsed because of centuries of unchecked population growth within a fragile environment. Recently, the notion of societal collapse has been questioned with the suggestion that extreme societal and demographic change occurred only after European contact in AD 1722. Establishing the veracity of demographic dynamics has been hindered by the lack of empirical evidence and the inability to establish a precise chronological framework. We use chronometric dates from hydrated obsidian artifacts recovered from habitation sites in regional study areas to evaluate regional land-use within Rapa Nui. The analysis suggests region-specific dynamics including precontact land use decline in some nearcoastal and upland areas and postcontact increases and subsequent declines in other coastal locations. These temporal landuse patterns correlate with rainfall variation and soil quality, with poorer environmental locations declining earlier. This analysis confirms that the intensity of land use decreased substantially in some areas of the island before European contact.Rapa Nui | population | obsidian | dating | collapse
A survey of the Easter Island landscape has resulted in the recognition of numerous lithic mulched household gardens and fields. It is proposed that lithic mulching was a technological innovation introduced to enhance the moisture retention capacity of the excessively drained island soils, and was an innovation incorporated into 茅lite managed field systems which arose in the early 15th century to meet the demands for surplus production.
The incongruity between the small and apparently impoverished Rapa Nui population that early European travelers encountered and the magnificence of its numerous and massive stone statues has fed a deep fascination with the island. Ethnographic and archaeological evidence suggest that the indigenous population was previously greater than the estimated 1,500-3,000 individuals observed by visitors in the eighteenth century. Our goal was to determine the maximum population that might have lived on the island by estimating its agricultural productivity in the time before European contact. To determine the agricultural potential of the island we sampled soils and established six weather stations in diverse contexts and recorded data over a 2-year period. We find that the island is wetter on average than previously believed. We also find that rainfall and temperature respond linearly to elevation, but a spatial model of precipitation requires correction for a rain shadow effect. We adapted to Rapa Nui an island-wide spatial model designed to identify agriculturally viable zones elsewhere in Polynesia. Based on functions relating climate and substrate age to measurements of soil base saturation, we identified 3,134 ha that were suitable for traditional dryland sweet potato cultivation, or about 19% of the 164 km 2 island. We used a nutrient-cycling model to estimate yields. Modeled yields are highly sensitive to nitrogen (N) inputs and reliable estimates of these rates are unavailable, requiring us to bracket the rate of N inputs. In the case of low N availability, yields under continuous cultivation were very small, averaging 1.5 t/ha of wet sweet potato tuber. When the N fixation rate was quadrupled sustainable yields increased to 5.1 t/ha. In each N scenario we used a model of food-limited demography to examine the consequences of altering agricultural practices, the labor supply, the ability of the population to control its fertility, and the presence or absence of surplus Puleston et al. Rapa Nui Population production to support social inequalities. In the low-N case viable populations average approximately 3,500 individuals across all parameter combinations, vs. 17,500 in the high-N case, although sustainable populations in excess of 25,000 were possible under some assumptions.
Prehistoric rapa Nui farmers used a variety of rock veneer and mulch gardens to increase crop productivity. These cultural features ranged from small ca. 10 x 10 m gardens, to much larger expanses of continuous rock concentrations covering many hectares. The rock gardens probably served several purposes, including protecting crops and soils from high winds, promoting water penetration, maintaining ground moisture, and reducing temperature fluctuations. in addition, soil nutrient dynamics might have been a factor in the construction of rock gardens. Analysis of soil nutrients within and outside of gardens suggests rainfall leaching significantly altered soil nutrients throughout the island. furthermore, rock gardens generally have elevated levels of nutrients in relation to non-garden settings. This could have been the result of rock gardens functioning as the physical foci for increased organic mulching, the construction of gardens in natural nutrient rich sweet spots, or the elevation of nutrient levels within gardens via the weathering of relatively soft basaltic rocks. The research presented here documents the elevated soil nutrient levels of gardens and begins to investigate the reasons for this and the impacts it might have had on crop productivity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations鈥揷itations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright 漏 2024 scite LLC. All rights reserved.
Made with 馃挋 for researchers
Part of the Research Solutions Family.