From the Cover: High-precision radiocarbon dating shows recent and rapid initial human colonization of East Polynesia (original) (raw)
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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. In a metaanalysis of 1,434 radiocarbon dates from the region, reliable short-lived samples reveal that the colonization of East Polynesia occurred in two distinct phases: earliest in the Society Islands A.D. ∼1025–1120, four centuries later than previously assumed; then after 70–265 y, dispersal continued in one major pulse to all remaining islands A.D. ∼1190–1290. 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. Our empirically based and dramatically shortened chronology for the colonization of East Polynesia resolves longstanding paradoxes and offers a robust explanation for the remarkable uniformity of East Polynesian culture, human biology, and language. Models of human colonization, ecological change and historical linguistics for the region now require substantial revision
RADIOCARBON DATES AND THE EARLIEST COLONIZATION OF EAST POLYNESIA: MORE THAN A CASE STUDY
Over the last 30 yr, there has been an ongoing debate on the dates and modes of the earliest colonization of East Polynesia, namely the Cook Islands, the 5 archipelagos of French Polynesia, the Hawai’i Islands, Easter Island, and New Zealand. At least 3 alternative models were proposed by Sinoto, Anderson, Kirch, and Conte, but interestingly all these mod- els basically relied on the same set of roughly 200 radiocarbon dates on various organic materials from archaeological exca- vations as far back as the 1950s. Some of the models differed by 500–1000 yr—for a proposed initial colonization around the turn of the BC/AD eras, if not considerably later. By comparing the different approaches to this chronological issue, it becomes evident that almost all known problems in dealing with 14C dates from archaeological excavations are involved: stratigraphy and exact location of samples, sample material and quality, inbuilt ages and reservoir effects, lab errors in ancient dates, etc. More recently, research into landscape and vegetation history has produced alternative 14C dating for early human impact, adding to the confusion about the initial stages of island colonization, while archaeological 14C dates, becoming increasingly “young” as compared to former investigations, now advocate a rapid and late (post-AD 900) colonization of the archipelagos. As it appears, the Polynesian case is more than just another case study, it’s a lesson on 14C-based archaeological chronology. The present paper does not pretend to solve the problems of early Polynesian colonization, but intends to con- tribute to the debate on how 14C specialists and archaeologists might cooperate in the future.
High-precision dating of colonization and settlement in East Polynesia
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. 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. 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 . 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 analysis created a more homogenous picture of East Polynesian colonization than is appropriate. Resolution of this debate will require not only rigorous protocols (1) but also targeted redating of key sites and more samples from across the region.
PNAS, 2020
The timing of human colonization of East Polynesia, a vast area lying between Hawai‘i, Rapa Nui, and New Zealand, is much de- bated 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 explora- tion 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 east- ward 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.
Radiocarbon, 1997
We present radiocarbon determinations for 271 New Zealand archaeological samples measured at the University of Waikato Radiocarbon Dating Laboratory between 1975 and A discard protocol is applied to the series and the list culled to winnow the acceptable dates from those that may incorporate error. None of the 221 acceptable 14C determinations older than 600 BP (in the case of terrestrial samples) or 930 BP (in the case of marine and estuarine shell) extends beyond cal AD 1250. This conclusion supports the short chronology model of New Zealand prehistory presented by Anderson (1991).
Late Holocene human-induced modifications to a central Polynesian island ecosystem
Proceedings of the National Academy of …, 1996
A 7000-year-long sequence of environmental change during the Holocene has been reconstructed for a central Pacific island (Mangaia, Cook Islands). The research design used geomorphological and palynological methods to reconstruct vegetation history, fire regime, and erosion and depositional rates, whereas archaeological methods were used to determine prehistoric Polynesian land use and resource exploitation. Certain mid-Holocene environmental changes are putatively linked with natural phenomena such as eustatic
Kirch and Kahn 2007 Review of Polynesian Prehistory
The pace of archaeological research in Polynesia has intensified in recent years, resulting in more than 500 new literature citations over the past decade. Fieldwork has continued in such previously well-studied archipelagoes as Tonga and Samoa in Western Polynesia, and Hawai'i and New Zealand in Eastern Polynesia, and has expanded into previously neglected islands including Niue, the Equatorial Islands, the Austral Islands, and Mangareva. The emergence of Ancestral Polynesian culture out of its Eastern Lapita predecessor is increasingly well understood, and the chronology of Polynesian dispersal and expansion into Eastern Polynesia has engaged several researchers. Aside from these fundamental issues of origins and chronology, major research themes over the past decade include (1) defining the nature, extent, and timing of long-distance interaction spheres, particularly in Eastern Polynesia; (2) the impacts of human colonization and settlement on island ecosystems; (3) variation in Polynesian economic systems and their transformations over time; and (4) sociopolitical change, especially as viewed through the lens of household or microscale archaeology. Also noteworthy is the rapidly evolving nature of interactions between archaeologists and native communities, a critical aspect of archaeological practice in the region.
A wiggle-match date for Polynesian settlement of New Zealand
A key horizon is provided by the Kaharoa Tephra, deposited from an eruption of Mt Tarawera, because just underneath this layer are the first signs of forest clearance which imply human settlement. The authors used a log of celery pine from within Kaharoa deposits to derive a new precise date for the eruption via "wiggle-matching" -matching the radiocarbon dates of a sequence of samples from the log with the Southern Hemisphere calibration curve. The date obtained was 1314 ± 12 AD (2σ error), and the first environmental impacts and human occupation are argued to have occurred in the previous 50 years, i.e. in the late 13 th -early 14 th centuries AD. This date is contemporary with earliest settlement dates determined from archaeological sites in the New Zealand archipelago.
World Archaeology, 1977
Polynesia has long been regarded as a cultural laboratory by anthropologists (Goodenough 1957; Sahlins 1957), who recognized a unique opportunity to study the adaptive variations of a single culture on its far-flung islands and island groups. Not only are human populations neatly confined on islands separated in many cases by considerable expanses of ocean, but the islands themselves vary greatly in size, resources and degree of isolation. Linguists, also, have found in the numerous discrete but closely related speech communities of Polynesia a fruitful field for the application of the comparative method (Elbert 1953 ; Pawley 1966). Despite many attempts to identify multiple waves of settlement in Polynesia (reviewed in Howard 1967), the orthodox view, to which archaeology has increasingly contributed, is that Polynesian language and culture developed their distinctive features inisolation, probably withinPolynesiaitself (Green 1967 ; Groube 1971). An older generation of ethnologists, concerned particularly with material culture, discussed cultural differences within Polynesia in terms of a variety of processes such as diffusion, local development and inter-island spread (Burrows 1938: 92; Buck 1944: 477-500). However, archaeologists working in Polynesia have been more concerned with establishing chronologies and sequences for individual island groups than with studying inter-island contact and influence. This is largely due to the fact that archaeology is a recent phenomenon in most of Polynesia-in many island groups the introduction of stratigraphie excavation and the application of radiocarbon dating were simultaneous. Moreover, Polynesian archaeology has always been fundamentally influenced by both romantic and scholarly interest in Polynesian origins and migrations. There has consequently been a great emphasis on identifying the date and origin of the first settlement of any island or island group. Although some archaeologists have acknowledged the existence and importance of borrowing in general terms (Green 1967: 216; Bellwood 1974), there has been little serious discussion of the question. Rather, there has been tacit acceptance that something akin to the founder principle of biology may have operated (Vayda and Rappaport 1963) and that later arrivals would have had little effect on established cultures (Sharp 1956: 71). Nor have the advantages and disadvantages of studying island cultures been much discussed by Polynesian archaeologists. Polynesia presents, for example, all the features listed by Evans (1973) in his discussion of islands as laboratories; such features form part of the overall concept of Polynesia as a cultural laboratory but have not been fully exploited in recent analyses of the area's prehistory.
Refining the chronology for west polynesian colonization: New data from the Samoan archipelago
The timing and unprecedented speed of the Lapita migration from the western edge of Oceania to western Poly-nesia in the Central Pacific have long been of interest to archaeologists. The eastern-most extent of that great human migration was the Samoan Archipelago in West Polynesia, although critical questions have remained about the timing and process of Samoan colonization. To investigate those questions, we carried out a Bayesian analysis of 19 radiocarbon dates on charcoal and 8 uranium-thorium (U-Th) series coral dates from four archaeological sites on Ofu Island in the eastern reaches of Samoa. The analysis indicates initial settlement of Ofu at 2717–2663 cal BP (68.2%) by people using Plainware rather than the diagnostic dentate-stamped Lapita pottery. This date range indicates that there is not a significant chronological gap between Lapita and Plainware sites in Samoa, which holds implications for modeling the settlement process in the Central Pacific.