Variation in Rapa Nui (Easter Island) land use indicates production and population peaks prior to European contact

Abstract

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

Concept Map to Visualize Opposite Perspectives of Rapa Nui History as a Whole

“…An alternative path is proposed by Christopher Stevenson and colleagues, who proposed the presence of a mosaic of different levels of food production in the Island and that although there have been declines; there was no ecological or agricultural collapse before the arrival of Europeans on the island. 9 Mara A Mulrooney 52 and colleagues also reached the same conclusion when presenting data on land use in Hanga Ho'onu during the period between 1700 and 1759 CE. 52 They said they found records of a slight decline in land use activity during this period, followed by a dramatic decline between 1750 and 1799 CE.…”

“…The island presents a weak annual cycle of monthly mean temperature (between 18.0 and 23.8°C) and annual rainfall varies from 630 to 2100 mm depending on the locality around the island. 9,10 Winds are a near constant occurrence and are present throughout the day. The southeasterly trade winds predominate from September to June and the northeasterly trade winds occur during July and August 11 There are no permanent streams or rivers on the island but there are three freshwater crater lakes (known as rano), at Rano Kau, Rano Raraku and Rano Aroi and a spring (puna) near Puna Pau.…”

“…Nevertheless, they disagreed with the notion of a broad or total collapse of the Rapanui before contact with the Europeans. 9 Burning can also be added as a reason for Rapa Nui landscape transformation: Forest clearance can be associated with the necessity for firewood used in daily activities. This idea was contested by Rosalind L Hunter Anderson who said that no palm wood has been identified as household fuel and that this was in tune with practices elsewhere in the Pacific, where people used to have dry husks and shells of coconuts, as well as dead branches and rotten tree trunks or a variety of trees as the usual cooking fuels.…”

Diet of the prehistoric population of Rapa Nui (Easter Island, Chile) shows environmental adaptation and resilience

“…They found greatest isotope discrimination associated with denitrification expressed in the plant‐soil cycle at levels of mean annual precipitation less than about 2500 mm year −1 . Modern mean annual rainfall on Rapa Nui is less than about 2100 mm year −1 (Stevenson et al, 2015), thus if biogeochemical cycling in Hawaiian forest volcanic soils is a reasonable analog for soils in lithic mulch gardens and manavai then denitrification and 15 N‐enrichment in plants growing in these soils is expected.…”

“…Recent archaeological research has brought such Malthusian claims into question: the arrival of the Pacific rat ( Rattus exulans ) shortly after the island's colonization may have extensively contributed to the palm forest's demise (Hunt, 2007) and with the use of fire the island was transformed into an agricultural landscape (Hunt & Lipo, 2006). Revised chronologies indicate settlement of Rapa Nui centuries later than previously supposed, with evidence for a more balanced use of the environment and a greater degree of human adaptability to a changing ecosystem than the “ecocide” model purports (Hunt & Lipo, 2006; Stevenson et al, 2015). Knowing past diets is crucial for understanding the impacts of human occupation on Rapa Nui.…”