Bayesian Radiocarbon Dating

The Khao Wong Prachan Valley of central Thailand is one of four known prehistoric loci of copper mining, smelting and casting in Southeast Asia. Many radiocar-bon determinations from bronze-consumption sites in northeast Thailand date the earliest copper-base metallurgy there in the late second millennium BC. By applying kernel density estimation analysis to approximately 100 new AMS radiocarbon dates, the authors conclude that the valley's first Neolithic millet farmers had settled there by c. 2000 BC, and initial copper mining and rudimentary smelting began in the late second millennium BC. This overlaps with the established dates for Southeast Asian metal-consumption sites, and provides an important new insight into the development of metallurgy in central Thai-land and beyond.

In this paper, we examine the series of AMS radiocarbon measurements (N = 52) obtained from the Late Bronze Age settlements of Kamennyi Ambar and Usty’e I in the Southern Trans-Urals, Russia. The exploratory data analysis applied to uncalibrated dates allows for the batches and outliers isolation. Furthermore, based on the facts of stratigraphy and application of the Bayesian statistics, we reconstruct the chronology, estimate spans of habitation, and discuss issues of the existing samples. As the first step of the analysis, we consider archaeological contexts of the measurements and statistically identify apparent outliers. Despite the small sample size, the dataset from Ust’ye I obtained in the way that allows to date stratigraphically isolated construction/utilization episodes and thus are highly reliable. At least five measurements from Kamennyi Ambar date the natural events before the settlement construction and serve as upper limits in models. In the second stage of the analysis, the Bayesian models of the sites’ chronology constructed with OxCal 4.3. For Ust’ye I, we designed a three-phase model that allows us to date two early habitational phases during which the walls and ditches were built around the settlement. The third phase defines the lower limit of the previous period, as this phase consists of a single radio-carbon measurement. The model suggests the existence of the gap between the two earliest stages, associated with the Sintashta and Petrovka ceramic types. While the sample size is small, this hypothesis agrees well with the site’s stratigraphy, as the settlement was re-modeled entirely at least once. We designed two models for Kamennyi Ambar. The first model includes all available data and consists of three phases: 1) natural events before the settlement construction; 2) the early «walled» phase; 3) the late «unwalled» phase. The second model incorporates data on the wells’ stratigraphy and uses only measurements from the wells. The models almost the same for the early habitational phase, but the modeled chronology of the late phase differs drastically, as the wells-based model condenses the phase and pushes it earlier. Further, the models suggest that Kamennyi Ambar existed only for about 50 years, and Usty’e I for nearly 100 years. The habitational phases within the same periods are partially desynchronized, and possible gaps in the habitation suggested by the models. One possible explanation of the short-term habitation spans and differences is that people needed to resettle regularly as resource depletion made the areas inhospitable for the communities of the livestock breeders.

Pottery is one of the most commonly recovered artefacts from archaeological sites. Despite more than a century of relative dating based on typology and seriation, accurate dating of pottery using the radiocarbon dating method has proven extremely challenging owing to the limited survival of organic temper and unreliability of visible residues. Here we report a method to directly date archaeological pottery based on accelerator mass spectrometry analysis of 14C in absorbed food residues using palmitic (C16:0) and stearic (C18:0) fatty acids purified by preparative gas chromatography. We present accurate compound-specific radiocarbon determinations of lipids extracted from pottery vessels, which were rigorously evaluated by comparison with dendrochronological dates and inclusion in site and regional chronologies that contained previously determined radiocarbon dates on other materials. Notably, the compound-specific dates from each of the C16:0 and C18:0 fatty acids in pottery vessels provide an internal quality control of the results6 and are entirely compatible with dates for other commonly dated materials. Accurate radiocarbon dating of pottery vessels can reveal: (1) the period of use of pottery; (2) the antiquity of organic residues, including when specific foodstuffs were exploited; (3) the chronology of sites in the absence of traditionally datable materials; and (4) direct verification of pottery typochronologies. Here we used the method to date the exploitation of dairy and carcass products in Neolithic vessels from Britain, Anatolia, central and western Europe, and Saharan Africa.

https://rdcu.be/b3s6J (online pdf)

A closely controlled radiocarbon sequence for the EB I-III, compiled over six seasons of excavations at Tel Bet Yerah, Israel, provides new information on the EB I-II and II-III transitions. These dates support the possibility of a decades-long overlap between some late EB I and early EB II sites and indicate a mid-to late 29th-century cal BC date for the introduction of Khirbet Kerak Ware in the southern Levant. South Levantine EB II is shown to co-extend neatly with the First Dynasty of Egypt.

Article available at:
https://www.tandfonline.com/doi/full/10.1080/00758914.2020.1727238
For a free eprint copy:
https://www.tandfonline.com/eprint/SWEWDD9IXW4NWIDZ2KKQ/full?target=10.1080/00758914.2020.1727238

The early Holocene in North Africa remains a poorly known period, documented unequally by region. Eastern Algeria and Tunisia have the greatest number of deposits, but most were excavated decades ago without the controls and recording required for modern interpretation. The chronological framework is based on radiocarbon (14 C) dates that are also old, for the most part. Recent work on Mesolithic lithic industries of Western Europe has enabled us to revive the hypothesis of the existence of contacts between the northern and southern shores of the western Mediterranean at least by the 6th millennium cal BC. A collective research program was conducted in 2016-2017 to test this hypothesis with a particular focus on documenting the technological traditions in the lithic industry and situating them precisely in time. We have 46 new radiocarbon dates that were recently carried out on previously excavated Algerian sites, some of which contain several levels, allowing the construction of Bayesian models. These new measures reinforce the hypothesis of contacts between Europe and Africa by demonstrating the contemporaneity of similar technological processes. Above all, they make it possible to accurately refine the chronology of the main cultural entities of the Maghreb at the beginning of the Holocene.

Human settlement of the Caribbean represents the only example in the Americas of peoples colonizing islands that were not visible from surrounding mainland areas or other islands. Unfortunately, many interpretive models have relied on radiocarbon determinations that do not meet standard criteria for reporting because they lack critical information or sufficient provenience, often leading to specious interpretations. We have collated 2484 radiocarbon determinations, assigned them to classes based on chronometric hygiene criteria, and constructed Bayesian colonization models of the acceptable determinations to examine patterns of initial settlement. Colonization estimates for 26 islands indicate that (i) the region was settled in two major population dispersals that likely originated from South America; (ii) colonists reached islands in the northern Antilles before the southern islands; and (iii) the results support the southward route hypothesis and refute the "stepping-stone model."

European metal artifacts in assemblages from sites predating the physical presence of Europeans in Northern Iroquoia in present-day New York, USA and southern Ontario, Canada have been used as chronological markers for the mid-sixteenth century AD. In the Mohawk River Valley of New York, European metal artifacts at sites pre-dating the physical presence of Europeans have been used by archaeologists as a terminus post quem (TPQ) of 1525 to 1550 in regional chronologies. This has been done under the assumption that these metals did not begin to circulate until after sustained European presence on the northern Atlantic coast beginning in 1517. Here we use Bayesian chronological modeling of a large set of radiocarbon dates to refine our understanding of early European metal circulation in the Mohawk River Valley. Our results indicate that European iron and cuprous metals arrived earlier than previously thought, by the beginning of the sixteenth century, and cannot be used as TPQs. Together with recent Bayesian chronological analyses of radiocarbon dates from several sites in southern Ontario, these results add to our evolving understanding of intra-regional variation in Northern Iroquoia of sixteenth-century AD circulation and adoption of European goods.

OPEN ACCESS:
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0226334