Oscillating Climate and Socio-Political Process: The Case of the Marquesan Chiefdom, Polynesia

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Introduction

The appearance of novel human behaviours and accelerated social processes is often associated with environmental change. Marked climate variability in particular, has been tied to subsistence change, technological innovations, intensified cultural interaction and sometimes social collapse (e.g. Sherratt 1997; deMenocal 2001). Historically, exploration of the relationships between climate change and social process has been most active in temperate regions, where high-resolution climate proxy records have a lengthy history. In the tropics, however, many traditional proxies are lacking (e.g. ice-cores) or are weak (e.g. tree-rings). In the last two decades this situation has changed, as natural scientists seek to understand the Pacific-centred El Nino-Southern Oscillation (ENSO), the Interdecadal Pacific Oscillation (IPO) (Power et al. 1999), and the mechanisms of modern global warming. Oxygen isotope records from tropical fossil corals are an important new proxy and, alongside sophisticated computer modelling, are offering new insights into both regional patterns and inter-regional teleconnections. There are now unprecedented opportunities for assessing the impact of climate variability on prehistoric Pacific peoples, biota, and landscapes. In this paper, the Marquesas Islands are used to examine the influence of multiple sca]es of climate variability on social structure, the latter potentially a crucial adaptive mechanism for complex sedentary agrarian societies. I argue that in localities where climate is unpredictable, perturbations common, and the risks of resource instability high, as in the Marquesas, socio-political systems that incorporate flexibility are advantageous.

Climate variability in the Marquesas Islands

Human arrival in the Marquesas Islands (Figure 1), from islands to the west, dates to between AD 700 and 1000 (Anderson & Sinoto 2002; Allen 2004). The narrow coastal plains and restricted valley bottoms offered limited areas for settlement, while local marine environments differed, cora] reefs being uncommon, lagoons lacking, and near-shore waters frequently deep. Moreover, the often rugged topography (Figure 2) and steep coastlines constrained inter-valley travel and communication. These features were, in and of themselves demanding, but the real challenges for prehistoric Marquesans were climatic. Lying between 7[degrees]50' and 11[degrees]35' S latitude, local temperatures are mild and stable (25-27[degrees]C), but interannual rainfall can be marked. Spatial variability is notable, with annual rainfall averages varying from 700mm in leeward areas to nearly 1500mm on windward coasts (Cauchard & Inchauspe 1978; Addison 2006) (Figure 3). It is droughts, however, that the islands are best known for and which captured the attention of early visitors, effectively from 1774 forward (Table 1). Missionary William Crook (2007 [1797-99]), beach-comber Edward Robarts (1974 [1797-1824]), and others (Wilson 1799: 131) commented on their effects, including the devastating famines which often followed. An early nineteenth-century drought saw 200-300 people perish in leeward Taioha'e Valley (Robarts 1974), while two-thirds of the island's population reportedly succumbed (Garcia in Suggs 1961: 191); on arid Ua Pou Island, entire valleys were depopulated (Robarts 1974: 274). Recent meteorological records re-enforce the view that the drier leeward communities surfer more, experiencing less average precipitation and more inter-annual variability (Figure 3; Rolett 1998: 25; Addison 2008).

The recurrent nature of Marquesan droughts and famines is captured in local traditions (Table 2). These oral histories inscribed the impacts and periodicity of drought on the collective cultural consciousness through highly descriptive names, such as the seven-year Ivi omo famine, literally 'to suck bones'. Chaulet (in Thomas 1990) recorded traditions relating to six major famines--disasters which were also alluded to in chants (Elbert 1941). …