Dating in samoa
Here accuracy is defined based on those samples that can provide a date that is the “true” age of the sample within the statistical limits of the date.
Precision is controlled by small laboratory measurement and calibration errors.
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.
Migration into eastern Polynesia began after a 1,800-y pause since the first settlement of Samoa, ∼800 B. (12), which implies a relatively sudden onset of whichever environmental or cultural factors were involved.
Our results show that, quite soon after reaching the central islands, Polynesian seafarers discovered nearly every other island of the eastern Pacific within about one century, a rate of dispersal unprecedented in oceanic prehistory.
Rather, our results indicate, quite simply, that widely accepted, longer chronologies for the region have been founded on materials (i.e., unidentified charcoal, long-lived plant materials, bone, and marine shell) that are inappropriate for precise radiocarbon dating of a relatively recent event, and where large measurement errors, ΔR variability, calibration issues, and additional uncertainties (e.g., from inbuilt age or contamination) associated with such samples can lead to inaccuracy and imprecision.Solid blue line = cumulative probability (right axis) which provides a means of assessing our confidence that colonization occurred no later than a particular date. 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).Solid blue line = cumulative probability (right axis) which provides a means of assessing our confidence that colonization occurred no later than a particular date. 3); without exception, the range for all Class 1 calibrated dates (68% probability; = 207) is considerably narrower than it is for Class 2 and 3 dates, regardless of their individual stratigraphy or context. These remote islands, from the tropic to sub-Antarctic oceans, were all colonized in one major pulse between A. It is conceivable that the Gambiers were found during early island hopping eastward from the Society Islands, but more dating of short-lived materials is needed to support that proposition. This clearly demonstrates that even a relatively small subset of precise radiocarbon dates on highly reliable samples is capable of providing a secure chronology, both from relatively small islands such as Rapa Nui, and from New Zealand, the largest and most topographically complex island group in Polynesia. The results also shorten by centuries the chronologies proposed for East Polynesian islands by Spriggs and Anderson (5), and confirm the growing trend of shorter chronologies emerging from recent studies on individual East Polynesian islands (3, 4, 6, 7, 18).The reliable Class 1 dates consistently reveal a short chronology for each island or archipelago where data are available. Our LAEM and our EAEM for initial colonization are listed below each island group and are represented by the yellow band.In contrast, Class 2–3 dates, which are based on materials that have a high risk of imprecision and/or inaccuracy, have a larger spread of ages, and these are often used to support longer chronologies in the region.(A) Estimates for the timing of colonization for East Polynesian archipelagos or islands. (B) Distinct separation between colonization ages for the Society Islands (and possibly Gambier) vs. Our LAEM and our EAEM for initial colonization are listed below each island group and are represented by the yellow band.