No abstract

The timing of human colonization of East Polynesia, a vast area lying between Hawai‘i, Rapa Nui, and New Zealand, is much debated and the underlying causes of this great migration have been enigmatic. Our study generates evidence for human dispersal into eastern Polynesia from islands to the west from around AD 900 and contemporaneous paleoclimate data from the likely source region. Lake cores from Atiu, Southern Cook Islands (SCIs) register evidence of pig and/or human occupation on a virgin landscape at this time, followed by changes in lake carbon around AD 1000 and significant anthropogenic disturbance from c. AD 1100. The broader paleoclimate context of these early voyages of exploration are derived from the Atiu lake core and complemented by additional lake cores from Samoa (directly west) and Vanuatu (southwest) and published hydroclimate proxies from the Society Islands (northeast) and Kiribati (north). Algal lipid and leaf wax biomarkers allow for comparisons of changing hydroclimate conditions across the region before, during, and after human arrival in the SCIs. The evidence indicates a prolonged drought in the likely western source region for these colonists, lasting c. 200 to 400 y, contemporaneous with the phasing of human dispersal into the Pacific. We propose that drying climate, coupled with documented social pressures and societal developments, instigated initial eastward exploration, resulting in SCI landfall(s) and return voyaging, with colonization a century or two later. This incremental settlement process likely involved the accumulation of critical maritime knowledge over several generations.

East Polynesia was the geographic terminus of prehistoric human expansion across the globe and the southern Cook Islands, the first archipelago west of Samoa, a gateway to this region. Fourteen new radiocarbon dates from one of the oldest human settlements in this archipelago, the Ureia site (AIT-10) on Aitutaki Island, now indicate occupation from cal AD 1225–1430 (1σ), nearly 300 yr later than previously suggested. Although now among the most securely dated central East Polynesian sites, the new age estimate for Ureia places it outside the settlement period of either the long or short chronology models. The new dates have, however, led to a comfortable fit with the Ureia biological evidence, which suggests not a virgin landscape, but a highly a modified fauna and flora. The results also provide the first systematic demonstration of inbuilt age in tropical Pacific trees, a finding that may explain widely divergent 14C results from several early East Polynesian sites and has implications for the dating of both island colonization and subsequent intra-island dispersals.

The concepts of style and function are theoretically defined from a neo-Darwinian perspective and the expected spatial-temporal distributions of each kind of trait outlined. Fish-hook assemblages from Aitutaki, Cook Islands, are examined using this framework and related to previously studied collections. Emerging stylistic patterns support notions of interaction between certain East Polynesian archipelagos around the 14th century AD.

Pacific archaeologists, geographers, and other social scientists have long used a model of Late Holocene climate change based largely on other regions of the world. In high-latitude regions, two major climate periods have been recognized: the Medieval Warm Period, dated to ca. AD 900-1200, and the Little Ice Age, dated to ca. AD 1550-1900. However, new evidence from long-lived Pacific corals, along with more general climate modelling, suggests that while the rest of the world was experiencing the Medieval Warm Period, conditions in the tropical Pacific were cool and possibly dry. Similarly, during the Little Ice Age the central Pacific was comparatively warm and wet and stormy conditions more common. A significant body of new evidence points to substantial climate variability in the central Pacific over the past millennium. Changing background climate, El Niño-Southern Oscillation variability, and the potential for regional variation are here considered with an eye to understanding the potential influence of climate on prehistoric human populations in the central Pacific region. For the past 50-odd years, Pacific archaeologists, geographers, and other social scientists have been using a model of Late Holocene climate change based largely on climate variability known from other regions of the world (e.g., Fagan 2000; Grove 1988; Lamb 1965). Until recently, there was little reason to suspect that conditions in the central Pacific diverged from those of the Northern Hemisphere, where two major climate periods are recognized: the Medieval Warm Period (MWP, also known as the Little Climatic Optimum), dated to ca. AD 900-1200, and the Little Ice Age (LIA), when temperatures were up to 1.2ЊC cooler (relative to the long-term average), dated to ca. AD 1550-1900 (following Jones, Osborn, and Briffa 2001, 665). Increasingly, however, there is evidence to suggest global variability in the timing, duration, and character of these two periods (Jones et al. 1998; Jones, Osborn, and Briffa 2001; Jones and Mann 2004). In the central Pacific, both observational studies and climate modelling now suggest that the MWP was relatively cool and the LIA relatively warm, the inverse of Northern Hemisphere conditions. Further, other parameters of climate may have been variable within the Central Pacific region. While not promoting an environmental determinist perspective, I argue that it is necessary to ᭧ 2006 by The Wenner-Gren Foundation for Anthropological Research.