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European voyaging in the Atlantic and Indian Ocean in the 15th century).However, environmental factors or disaster could also have been influential.For each graph, individual ranges (68% probability) of Class 1 calibrated radiocarbon dates are shown as black horizontal lines; circles represent median (bottom axis). The high proportion of unidentified charcoal in Class 3 shows this category of dated materials in the dataset also tends to have large measurement errors. Age estimates for initial colonization of the Gambier archipelago are unusually broad (167-y difference between the EAEM and LAEM, i.e., between A. ∼11) compared with all other islands (average difference of 55 y between earliest and latest estimates). ∼1219–1266, respectively), some 200–500 y later than widely accepted (16, 17), placing them in close agreement with both New Zealand and Rapa Nui.Red dashed line indicates sum of probability distributions (left axis). 1200 based on the assumption that we have 100% confidence that colonization had occurred by this time; and for the remaining islands with Class 1 dates, this was set to A. The distribution of calibrated age ranges for all classes of radiocarbon dates shows a clear pattern across the entire region (Fig. 1025 to 1520, in contrast to those of Class 2–3 dates, which extend back to 500 B. This pattern reflects the higher precision and accuracy of the reliable targets that make up Class 1 dates (i.e., short-lived materials with SEs and Fig. Using our models, we can show a robust and securely dated two-phase sequence of colonization for East Polynesia: earliest in the Society Islands A. ∼1025–1120, four centuries later than previously assumed, and significantly before (by ∼70–265 y) all but one (Gambier) of the remote island groups with Class 1 dates. This is caused by one date in the Gambier group [Beta-271082: 970 ± 40 BP on carbonized ), leaving initial colonization age ambiguously between that of the central and marginal East Polynesian islands. ∼1200–1253, respectively) but with much larger sets of Class 1 dates. They are also in close agreement with age estimates for initial colonization on the remaining island groups, with Class 1 dates including Line, Southern Cooks, and the sub-Antarctic Auckland Island, which all show remarkably contemporaneous chronologies within radiocarbon dating error (Fig. The unity in timing of human expansion to the most remote islands of East Polynesia (encompassing the triangle made between Hawaii, Rapa Nui, and Auckland Island) is even more extraordinary considering these islands span a vast distance of both longitude and latitude (Fig. Collectively, these results, based on only the most reliable samples, provide a substantially revised pattern of colonization chronology for East Polynesia, which shortens the age for initial colonization in the region by up to 2,000 y, depending on various claims asserted for earlier chronologies (3, 9, 10).As the number of radiocarbon dates from East Polynesia has increased 10-fold over those available in 1993 (5), an attempt to resolve the frustrating problem of colonization chronology for the region is now opportune.Our main objective is to establish the most accurate age, or ages, for initial colonization in East Polynesia.
We first categorized all radiocarbon-dated materials into one of six sample material types: short-lived plant, long-lived plant, unidentified charcoal, terrestrial bird eggshell, bone, and marine shell (Fig. Dates on these materials were then sorted into reliability classes, according to whether there was potential for any disparity between the age of the radiocarbon event (i.e., Fig. Calibration probabilities were then calculated for the subset of reliable dates to derive the most precise (within radiocarbon calibration error) estimate for the age of initial colonization on all East Polynesian island groups (.The 15 archipelagos of East Polynesia, including New Zealand, Hawaii, and Rapa Nui, were the last habitable places on earth colonized by prehistoric humans.The timing and pattern of this colonization event has been poorly resolved, with chronologies varying by 1000 y, precluding understanding of cultural change and ecological impacts on these pristine ecosystems. We show that previously supported longer chronologies have relied upon radiocarbon-dated materials with large sources of error, making them unsuitable for precise dating of recent events.During the last prehistoric expansion of modern humans, Polynesians from the Samoa-Tonga area dispersed through more than 500 remote, subtropical to subantarctic islands of East Polynesia (a cultural region encompassing the islands of New Zealand, Chathams, Auckland, Norfolk, Kermadecs, Societies, Cooks, Australs, Gambier, Tuamotu, Marquesas, Line, Rapa Nui, and Hawaii), an oceanic region the size of North America (Fig. The timing and sequence of this expansion, debated vigorously since Europeans rediscovered the islands of East Polynesia (1, 2) and most intensively with the advent of radiocarbon dating (3, 4), remains unresolved. This analysis shortened East Polynesian prehistory just at the time when accelerator mass spectrometry (AMS) radiocarbon dating became available for very small samples (e.g., individual seeds).On many islands, irreconcilable long and short settlement chronologies coexist that vary by more than 400–1,000 y (4). 600–950 in the central, northern, and eastern archipelagos, and no earlier than A. Subsequent studies using precise AMS dating of short-lived materials alone have generally supported short chronologies (4, 6–8).