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Wilmshurst et al. (1) proposed recent and rapid colonization of East Polynesia based on analysis of 1,434 radiocarbon determinations. We commend the development of rigorous and replicable radiocarbon protocols that emphasize accuracy and precision, but we found (i) inaccuracies in their originally published supplementary data table, (ii) problems with their criteria for exclusion and inclusion of valid colonization estimators (i.e., Class 1 dates), and (iii) biases in their statistical analysis.Our review of their originally published 207 Class 1 dates identified 112 incorrectly reported 14 C laboratory numbers and 123 misreported conventional radiocarbon ages, with 110 of these reported as at least 100 y too recent. Additionally, source citations were misassigned for 70 Class 1 dates. Nonetheless, our reanalysis using corrected data provides probability distributions broadly similar to figure 4 in ref.1. The errors have been corrected in a revised table.We suggest that some reliability classification criteria for Class 1 dates are overly strict and exclude accurate estimators of early cultural activity. Specifically, several reliable dates (on archaeological criteria) with SEs of 10-15% are excluded by their 10% threshold, whereas elimination of all marine samples, even in cases where local ΔR values are established (2), seems inappropriate.Inclusion of dates as recent as 300 B.P. and samples from nonbasal strata biased their age estimation models in favor of a short chronology. These late dates skewed their sum of probability distributions to the more recent period, thereby affecting the cumulative probability outcomes. Fig. 1 shows the impact of removing late dates and how easily such probability curves can be affected by small sample sizes, which is the case for most archipelagoes.Also, cutoff points are assigned to identify the upper limit of likely colonization (e.g., 1300 A.D. for most islands), times by which Wilmshurst et al. (1) had "100% confidence that colonization had occurred" (1). These are based on the skewed probability sums (above), which influenced the slope of the cumulative probability line. Using only the earliest Class 1 dates (specific to each archipelago) results in different summed probability and cumulative curves as well as different colonization models (Fig. 2).Overall, we agree with Wilmshurst et al.(1) and others (3) that East Polynesia was settled more recently than previously argued. However, their statistical model was built on 14 C dates with calibrated probabilities that were summed, normalized, and then compared with a certainly settled date. We suggest that the analysis of probability distributions is more appropriate for identifying the timing of established settlement rather than initial colonization (4). Our reanalysis using their approach and a corrected version of their table S1 for Class 1 dates suggest that, in several cases, colonization probably occurred earlier than they proposed (1). We argue that several aspects of their reliability classification and statistical...

Prehistoric rapa Nui farmers used a variety of rock veneer and mulch gardens to increase crop productivity. These cultural features ranged from small ca. 10 x 10 m gardens, to much larger expanses of continuous rock concentrations covering many hectares. The rock gardens probably served several purposes, including protecting crops and soils from high winds, promoting water penetration, maintaining ground moisture, and reducing temperature fluctuations. in addition, soil nutrient dynamics might have been a factor in the construction of rock gardens. Analysis of soil nutrients within and outside of gardens suggests rainfall leaching significantly altered soil nutrients throughout the island. furthermore, rock gardens generally have elevated levels of nutrients in relation to non-garden settings. This could have been the result of rock gardens functioning as the physical foci for increased organic mulching, the construction of gardens in natural nutrient rich sweet spots, or the elevation of nutrient levels within gardens via the weathering of relatively soft basaltic rocks. The research presented here documents the elevated soil nutrient levels of gardens and begins to investigate the reasons for this and the impacts it might have had on crop productivity.

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Reconstructing routes of ancient long-distance voyaging, long a topic of speculation, has become possible thanks to advances in the geochemical sourcing of archaeological artifacts. Of particular interest are islands classified as Polynesian Outliers, where people speak Polynesian languages and have distinctly Polynesian cultural traits, but are located within the Melanesian or Micronesian cultural areas. While the classification of these groups as Polynesian is not in dispute, the material evidence for the movement between Polynesia and the Polynesian Outliers is exceedingly rare, unconfirmed, and in most cases, nonexistent. We report on the first comprehensive sourcing (using a portable X-ray fluorescence spectrometer) of obsidian and volcanic glass artifacts recovered from excavations on the Polynesian Outlier island of Tikopia. We find evidence for: (1) initial settlement followed by continued voyages between Tikopia and an island Melanesian homeland; (2) long-distance voyaging becoming much less frequent and continuing to decline; and (3) later voyaging from Polynesia marked by imports of volcanic glass from Tonga beginning at 765 cal yr BP (±54 yr). Later long-distance voyages from Polynesia were surprisingly rare, given the strong cultural and linguistic influences of Polynesia, and we suggest, may indicate that Tikopia was targeted by Tongans for political expansion.