Bayesian Chronological Modeling Research Articles

Radiocarbon-Refined Archaeological Chronology and the History of Human Activity in the Southern Tarim Basin

Famous for Taklimakan, the world’s second largest sandy desert, the Tarim Basin in Xinjiang has long attracted researchers from various fields to investigate its paleoenvironment and antiquity. The southern part of this basin is an ideal region in which to investigate the interactions between humans and the environment due to its fragile habitat and prosperous ancient civilizations. However, the lack of direct radiocarbon dating data has caused the chronologies of some of the archaeological sites to be debatable, which hinders our ability to reconstruct historical patterns of human activity and further understand, in a coherent manner, their interaction with the environment. This study reports 25 new radiocarbon dates acquired from ten undated archaeological sites in the southern Taklimakan Desert in order to refine their chronologies. Based on this, a radiocarbon dataset was established to reveal the trajectory of human activity with the support of Bayesian chronological modeling. The results indicate a two-millennium continuous flourishing of the local society since the beginning of the first millennium BCE, as well as a peak of human activity during the Tang Dynasty (618–907 CE). The distinct trajectory of human activity in the southern Tarim Basin revealed by this study provides a solid foundation for further assessments of human–environment interaction in the Tarim Basin and along the Silk Road.

Monumental and Long-Lasting or Temporary and Performative? How did Neolithic Rondels Function? Radiocarbon Dating and Bayesian Chronological Modeling of the Rondel at Nowe Objezierze (Northwestern Poland)

ABSTRACT Radiocarbon dating and Bayesian chronology modeling have provided precise dating for the rondel at Nowe Objezierze (northwestern Poland). This monument, located in the farthest reaches of the “Danubian World,” sheds new light on rondels and the way they functioned. A total of 44 radiocarbon dates are now available for the site, and modeling of these (taking into account depositional processes and the results of palynological analysis) has identified plausible scenarios for its construction and use. The rondel was built around 4800 cal b.c. and operated for about three centuries. The cyclical digging and filling of ditches and the sequential establishment of new ones characterized the historical development of the site. The long duration of use of the site served as a base to analyze the potential construction technology and to propose the reconstruction of the appearance of the rondel.

SPATIOTEMPORAL PATTERNS ON THE APPEARANCE OF THE FIRST TRAPEZE INDUSTRIES IN THE LATE MESOLITHIC OF THE IBERIAN PENINSULA

ABSTRACTThe spread of trapeze industries (the creation of trapeze-shaped flint tips) during Late Mesolithic is one of the most disruptive phenomena of technological change documented in the European Prehistory. Understanding the chronological patterns of this process requires (i) a critical evaluation of stratigraphic relationship between trapeze assemblages and radiocarbon samples, and (ii) considering different levels of chronological uncertainty according to the inbuilt age of the samples and the calibration process. In this paper, we critically evaluate and analyze the radiocarbon record of the first trapeze industries in the Iberian Peninsula. A dataset of 181 radiocarbon dates from 67 sites dated to 8800–8200 cal BP was collected and evaluated following a strict data quality control protocol, from which 135 dates of 53 sites were retained and classified according to a reliability index. Then, three different phase Bayesian chronological models were created to estimate the duration of the first spread of trapezes across Iberia, considering different levels of chrono-stratigraphic resolution. We find that trapeze industries appeared in the eastern half of Iberia, over an area of 330,000 km2 between 8505–8390 and 8425–8338 cal BP, spanning 0–85 yr (95.4% CI). When the oldest evidence of trapezes from Portugal are considered, the probability distribution expands (8943–8457 and 8686–7688 cal BP), due to the chronological uncertainty of human samples with marine diet and regional ΔR values applied. For the eastern half of Iberia, the current evidence indicates a very rapid spread of trapeze industries initiated in the Central-Western Pyrenees, suggesting cultural diffusion within Mesolithic social networks as the main driving mechanism.

A multi-stage Bayesian modelling for building the chronocultural sequence of the Late Mesolithic at Cueva de la Cocina (Valencia, Eastern Iberia)

This paper presents a refined Mesolithic chronocultural sequence as a result of matching data provided by the set of archaeological research conducted at Cueva de la Cocina (Valencia, Spain) in the 20th and 21st centuries and the new radiocarbon dates record. Because available data are of different quality, we apply a methodological framework based on Bayesian modelling approaches. To do this, we systematically order each one of the archaeological registers and then combine the information in a unitary general chronology. Our novel approach introduces Bayesian modelling from a double analytical procedure: using Bayesian chronological models applied to the stratigraphic sequence of Pericot's excavation in Cocina cave we build a general phase model using data from multiple years of archaeological fieldwork. One the most reliable layers have been defined, we use this information to define the rest of the sequence through a Predictive Bayesian approach. This approach sheds light on evolutionary questions from a macroscale regarding the socioecological dynamics of the last hunter-gatherers and their role for explaining the subsequent agricultural spread.

Dorstone Hill: a Neolithic timescape

Studies of early fourth-millennium BC Britain have typically focused on the Early Neolithic sites of Wessex and Orkney; what can the investigation of sites located in areas beyond these core regions add? The authors report on excavations (2011–2019) at Dorstone Hill in Herefordshire, which have revealed a remarkable complex of Early Neolithic monuments: three long barrows constructed on the footprints of three timber buildings that had been deliberately burned, plus a nearby causewayed enclosure. A Bayesian chronological model demonstrates the precocious character of many of the site's elements and strengthens the evidence for the role of tombs and houses/halls in the creation and commemoration of foundational social groups in Neolithic Britain.

The Milky Way: Mobility and Economy at the Turn of the 3rd Millennium in Southern Central Europe

In the light of discussions surrounding the social changes attributed to the arrival of the Corded Ware culture in central Europe, here we investigate the economic strategies of one of the cultural complexes of the immediately preceding Late Neolithic. The Cham culture of southern Bavaria is characterised by a variety of economic choices but problems remain in synthesising and combining archaeozoological and archaeobotanical evidence. Using lipid residue analysis from Cham culture pottery excavated at the unenclosed settlement of Riedling, Lower Bavaria, we succeed in identifying a dairying economy at this time. Compound-specific lipid radiocarbon dates are then combined with other samples to provide a formal estimate for the duration of activity at Riedling and the first Bayesian chronological model for the Cham culture as a whole. Although data are currently not fine-grained enough to distinguish between competing models for site permanence, we suggest that the Cham culture pattern fits into a wider central European trend of greater mobility and economic flexibility in the pre-Corded Ware horizon, concluding that key economic strategies previously associated with ‘steppe invasions’ were already present in the preceding centuries. Finally, the demonstrated use of cups for milk-based products, as opposed to alcoholic drinks as previously suggested, leads us to propose possible alternative uses and users for these items.

Chronology construction in the borderlands: Bayesian modelling of Potomac Valley settlement histories

Bayesian modelling of radiocarbon dates to construct detailed chronologies has become a key methodology in North America's ‘historic turn,’ though the Middle Atlantic has seen few efforts to apply these techniques. Drawing from 70 legacy dates and 25 new assays, this study develops Bayesian chronological models for 10 Late Woodland (AD 900-1600) sites in the Potomac Valley. Our goal is to assess how the arrival of Luray communities impacted the region's settlement history. During the Late Woodland period Native communities tied to three cultural traditions established a series of towns in the Potomac Valley, at times close to one another. With evidence of population movements, intergroup violence, and coalescent communities, the Late Woodland Potomac Valley appears to have represented a dynamic borderland during these centuries. The chronology developed in this study points toward a landscape of settlements we have labelled Persistent Places, Unsettled Settlements, and Transitory Towns.

Bayesian chronology construction and substance time

Two views of archaeological time are distinguished; an event view that models stratigraphic relations, and a substance view that models genealogical relations among artifacts, including the three modes of change represented by branching, transformation, and reticulation. Chronology construction is more complex in substance time than it is in event time, which only concerns transformation. Allen's interval algebra can be used to specify the chronological relations associated with the modes of change, and these relations can be identified by post-processing the output from Bayesian chronological models. A worked example illustrates how identifying the chronological relations can aid construction of a phyletic seriation of beads recovered from Anglo-Saxon female graves. These results might encourage archaeologists to carry out chronology construction in substance time as an aid to historical inference.

Impacts of Early Holocene environmental dynamics on open‐air occupation patterns in the Western Mediterranean: insights from El Arenal de la Virgen (Alicante, Spain)

ABSTRACTOpen‐air sites represent a fundamental proxy of the Early Holocene adaptive systems in the Iberian Peninsula. However, its research potential for the study of human–environmental interactions has been minimally explored. In this work, we present the results of an integrated research programme focused on open‐area excavations at the Mesolithic site of Arenal de la Virgen (Alicante, Spain). Novel multi‐scalar geoarchaeological and archaeo‐stratigraphic studies, coupled with featured‐based palaeobotanical analysis, were used to design an extensive radiocarbon dating programme and produce different Bayesian chronological models. Our results distinguish two different Mesolithic occupation phases, dating to 9.3–9.1 and 8.6–8.3k cal a bp respectively, consisting of combustion features and lithic scatters. The comparison of occupational dynamics with the nearby palaeoecological records of Salines and Villena indicated that both Mesolithic phases occurred under relatively stable environmental conditions. The second Mesolithic phase, however, ended during the onset of the 8.2k cal a bp climatic event, when sedimentation processes shifted from soil formation to accretion of aeolian sands. We demonstrate that the end of the Mesolithic occupations at Arenal de la Virgen coincides with the cessation of radiocarbon‐dated activity in other open‐air Postglacial sites in the central Mediterranean region of Iberia.

Thirty years in the making: A critical overview of the Kura-Araxes periodization from a radiocarbon perspective

The chronology of the Kura-Araxes culture has long been a matter of debate, particularly as regards its internal periodization. To date, two main periodization systems have been proposed, which argue, respectively, for a three-part and two-part scheme. Despite the acquisition of new 14C and archaeological datasets, universal consent on this issue still hasn’t been reached. This paper reviews the state of the art in chronological studies on the Kura-Araxes culture and provides a critical assessment of the two periodization systems since the introduction of radiocarbon dating in the South Caucasus. The discussion demonstrates that the understanding of the Kura-Araxes chronology exceeds mere questions of ‘objective’ chronometric agreement, as seen in the way that different archaeological agendas have influenced the interpretation of ambiguous calibrated data, and vice versa. Finally, the paper highlights the potential of Bayesian chronological modeling to disambiguate chronometric evidence and exploit archaeological knowledge to the benefit of regionalized periodization frameworks.

The biodeterioration outbreak in Dunhuang Mogao Grottoes analyzed for the microbial communities and the occurrence time by C-14 dating

Mogao Grottoes, a UNESCO World Cultural Heritage Site since 1987, suffers from microbial colonization and deterioration of the wall paintings with the visible appearance of black spots and microbial biomasses in selected caves. In this study, next-generation sequencing (NGS) and microscopy analyses were combined to reveal the microbial community composition responsible for the biodeterioration. Results of scanning electron microscope (SEM), fluorescence microscopy, and polarizing microscopy showed that the existing microbial hyphae related to biodeteriorations were inviable. The dominant bacteria included Rhodococcus and Ralstonia, while Aspergillus species were the predominant fungi in samples of the black spots and microbial biomasses. In addition, radioactive 14C dating was applied to determine the possible infestation time of the fungal outbreak based on Bayesian chronological modeling. The original mural was most likely painted in the Five Dynasties and Ten Kingdoms (939–942 ca. AD), while the repainting time of the mural was most probable during the Song Dynasty (1002–1014 ca. AD), and the microbial biomasses were most likely formed in this historical period. With monitoring locations closer to the cliff, the higher bacterial diversity and lower fungal diversity detected were correlated with the higher relative humidity. Since the temperature and relative humidity are generally low in this area, being unsuitable for microbial growth presently or in the normal time of the past, either earthen plaster preparation before painting or heavy rainfall events combined with a leaky roof were most likely the initiators of the outbreak of the indigenous microbes on the wall paintings. This study provides useful evidence concerning the microbial community and the timing of microbial outbreak events on ancient wall paintings in such extremely arid climate conditions.

ASSESSING THE 14C MARINE RESERVOIR EFFECT IN ARCHAEOLOGICAL CONTEXTS: DATA FROM THE CABEÇUDA SHELL MOUND IN SOUTHERN BRAZIL

ABSTRACTPrehistoric shell mounds can be useful for the quantification of the radiocarbon marine reservoir effect (MRE) and, at the same time, knowledge about the MRE allows for the establishment of robust chronologies for these sites. This creates a loop in which the archaeological setting has a dual role: it is part of both the method and the application. Therefore, it is paramount to address these sites from both archaeological and environmental perspectives, investigating their origin and diagenesis in order to overcome biases caused by post-depositional alterations. In this study, samples of bone, charcoal and shell from a Late Holocene shell mound in Southern Brazil, the Sambaqui de Cabeçuda, were analyzed following a multidisciplinary approach to disentangle the complex relationships between archaeology and the environment. We performed X-ray diffraction, radiocarbon dating, stable isotopes (δ13C, δ18O, δ15N) and anthracology analyses as well as Bayesian Chronological Models and Isotope Mixing Models to assess the local MRE and to reconstruct the diet of Cabeçuda builders. Our results reveal a negative local correction for the MRE (ΔR = –263 ± 46 14C yr), expected for the lagoon next to the site, and diets with considerable intakes of marine proteins. We examine the implications of these results for the chronology of the site and discuss a series of complications when performing MRE studies using shell mound sites.

Bayesiansk kronologisk modellering som redskab i den lovpligtige arkæologi

Bayesiansk kronologisk modellering som redskab i den lovpligtige arkæologi

First high-resolution luminescence dating of loess in Western Siberia

The south of Western Siberia is an important part of the Eurasian loess belt, containing an extensive record of Quaternary landscape and climate evolution in up to 100 m thick loess deposits with as many as 10 pedocomplexes. However, this important Quaternary archive lacks a reliable absolute chronology, and this has prevented the linking of the widely accepted regional chronostratigraphic correlations with those of other parts of the Eurasian loess belt. Here we present the first results of detailed luminescence dating of the Late Pleistocene loess-palaeosol sequence at the Western Siberian stratotype section of Lozhok. According to the classical regional chronostratigraphic scheme, this sequence records the main stages of the environmental evolution of the region, including three palaeosols correlated with the warming stages of MIS 5e, MIS 5c and MIS 3. Our absolute chronology is based on 38 new luminescence ages (OSL, IR 50 , pIRIR 290 ). Good agreement between the OSL and pIRIR 290 ages suggests sufficient bleaching before deposition. The resulting chronology reveals that, rather than being only Upper Pleistocene in age, the loess-palaeosol sequence at Lozhok actually formed in the Middle and Upper Pleistocene. The ages of individual horizons do not correspond to the previously accepted stratigraphic units and morphological features of pedocomplexes. Our Bayesian chronological model reveals remarkable variation in dust accumulation and preservation at the site. The new results unambiguously identify the presence of an erosional boundary with a hiatus lasting ∼90 ka. The upper pedocomplex, immediately below this discontinuity, formed in sediment deposited between 131 ± 9 ka and 122 ± 11 ka and clearly corresponds to MIS 5. The lower pedocomplex is found in sediment deposited between 240 ± 12 and 199 ± 9 ka, and correlates closely with MIS 7. These new findings demonstrate the urgent need for a wider programme to date the main stratotypes of loess-palaeosol sections in Western Siberia. Only then can the global implications of the regional climate record in this important continental-scale archive be correctly interpreted.

ABSOLUTE CHRONOLOGY AT THE WATERLOGGED SITE OF LA DRAGA (LAKE BANYOLES, NE IBERIA): BAYESIAN CHRONOLOGICAL MODELS INTEGRATING TREE-RING MEASUREMENT, RADIOCARBON DATES AND MICRO-STRATIGRAPHICAL DATA

ABSTRACTSixty-two 14C dates are analyzed in combination with a recently established local floating tree-ring sequence for the Early Neolithic site of La Draga (Banyoles, northeast Iberian Peninsula). Archaeological data, radiometric and dendrochronological dates, as well as sedimentary and micro-stratigraphical information are used to build a Bayesian chronological model, using the ChronoModel 2.0 and OxCal 4.4 computer programs, and IntCal 2020 calibration curve. The dendrochronological sequence is analyzed, and partially fixed to the calendrical scale using a wiggle-matching approach. Depositional events and the general stratigraphic sequence are expressed in expanded Harris Matrix diagrams and ordered in a temporal sequence using Allen Algebra. Post-depositional processes affecting the stratigraphic sequence are related both to the phreatic water level and the contemporaneous lakeshore. The most probable chronological model suggests two main Neolithic occupations, that can be divided into no less than three different “phases,” including the construction, use and repair of the foundational wooden platforms, as well as evidence for later constructions after the reorganization of the ground surface using travertine slabs. The chronological model is discussed considering both the modern debate on the Climatic oscillations during the period 8000–4800 cal BC, and the origins of the Early Neolithic in the western Mediterranean region.

Blind dates: Exploring uncertainty in the radiocarbon evidence on the emergence of animal husbandry in the Dutch wetlands

The emergence of animal husbandry in the Netherlands remains the subject of much speculation. Challenges in identifying domesticated animals among the faunal remains, inconsistent excavation documentation, and flawed radiocarbon analysis have resulted in questionable chronologies. This paper examines the available radiocarbon evidence from selected sites which are the mainstay of early examples of domesticated animals in the Netherlands, between 5000 and 4000 BCE.1All radiocarbon dates given in this paper, denoted as BCE, are calibrated unless stated otherwise.1 We approach the legacy data in two ways: by employing principles of chronometric hygiene to reassess the radiocarbon datasets of selected sites and by exploring the use of such data for future studies in chronology by means of Bayesian chronological modelling. The latter is demonstrated with a case study, whereby we employ legacy data from Hardinxveld-Giessendam De Bruin in Bayesian models to demonstrate that, despite their shortcomings, such dates remain a valuable resource for much needed future chronological analysis.

Mainland-coastal interactions in East Borneo: Inter-site comparison and Bayesian chronological models of two Late Pleistocene–Holocene sequences (Liang Abu and Kimanis rock shelters)

In recent decades, East Borneo has become an increasingly important archaeological “hot-spot” in Island Southeast Asia as a result of early dates for rock art ca. 38,000 BP and the greater number of excavated sites that support a much longer period of human occupation. However, the chronology of settlement and adaptation to environmental changes during the Pleistocene–Holocene transition is still poorly known. Here we report on an excavation at the Liang Abu rock shelter which has contexts dating from the Late Pleistocene (12,660 ± 58 uncal. BP) to the present day, indicating a terminus ante quem (TAQ) for human occupation at 23,790 BP. We present the results of an attempt to systematically integrate and compare data from Liang Abu and Kimanis, a geographically close site with a previously published sequence. Particular attention is paid to post-depositional issues in tropical settings and to data compatibility, reuse, and reproducibility, relying on open-source software for data processing (R scripts) and Bayesian chronological modeling. Two Bayesian models are built and compared using the ChronoModel software, which can handle outliers and uncertainty (e.g., freshwater reservoir effect). This first inter-site comparison for Borneo results in a new chronology of human settlement and mainland–coastal interactions in East Borneo and paves the way for future regional synthesis.

The Appearance of Contracting Stem Dart Points in the Western United States, Diffusion or Migration?

Contracting stem dart points are assigned to various named types and are considered Archaic temporal markers, but their dating and geographic distribution remain somewhat variable and uncertain. Bayesian chronological modeling indicates contracting stem dart points were in use in the Colorado Plateau and Great Basin from 2210 cal BC through 710 cal BC. Comparative dating indicates contracting stem dart points did not arrive with farmers from Mexico, but rather, the dates and geographic distribution of the contracting stem points indicate this hafting style diffused rapidly throughout the western US.

Radiocarbon dating and Hallstatt chronology: a Bayesian chronological model for the burial sequence at Dietfurt an der Altm\xfchl \u2018Tennisplatz\u2019, Bavaria, Germany

This study is first attempt to refine Early Iron Age absolute chronology, specifically the timing of the Hallstatt C-D transition in southern Germany, using Bayesian chronological modelling of radiocarbon (14C) dates. The Hallstatt period (c.800–450 BC) marks the transition from prehistory to proto-history in Central Europe. The relative chronological framework for Hallstatt burials developed by the mid-twentieth century is still used today, but absolute dating is limited by the scarcity of dendrochronological dates and the perception that 14C dating in the Hallstatt period (HaC-HaD) is futile, due to the calibration plateau between c.750 and 400 cal BC. We present new AMS 14C dates on 16 HaC-HaD burials from a stratified sequence at Dietfurt an der Altmühl ‘Tennisplatz’ (Bavaria, Germany). This sequence is situated entirely on the ‘Hallstatt plateau’, but by combining 14C dating with osteological, stratigraphic, and typological information, we demonstrate that the plateau is no longer the ‘catastrophe’ for archaeological chronology once envisaged. Taking into account dendrochronological dating elsewhere, we show that at Dietfurt, the HaC-HaD transition almost certainly occurred before 650 cal BC, and most likely between 685 and 655 cal BC (68.3% probability), several decades earlier than usually assumed. We confirm the accuracy and robustness of this estimate by sensitivity testing. We suggest that it is now possible, and essential, to exploit the increased precision offered by AMS measurement and the IntCal20 14C calibration curve to re-evaluate absolute chronologies in Early Iron Age Europe and equivalent periods in other regions.

A multi-proxy assessment of the impact of environmental instability on Late Holocene (4500-3800 BP) Native American villages of the Georgia coast.

Circular shell rings along the South Atlantic Coast of North America are the remnants of some of the earliest villages that emerged during the Late Archaic (5000–3000 BP). Many of these villages, however, were abandoned during the Terminal Late Archaic (ca 3800–3000 BP). We combine Bayesian chronological modeling with mollusk shell geochemistry and oyster paleobiology to understand the nature and timing of environmental change associated with the emergence and abandonment of circular shell ring villages on Sapelo Island, Georgia. Our Bayesian models indicate that Native Americans occupied the three Sapelo shell rings at varying times with some generational overlap. By the end of the complex’s occupation, only Ring III was occupied before abandonment ca. 3845 BP. Ring III also consists of statistically smaller oysters harvested from less saline estuaries compared to earlier occupations. Integrating shell biochemical and paleobiological data with recent tree ring analyses shows a clear pattern of environmental fluctuations throughout the period in which the rings were occupied. We argue that as the environment became unstable around 4300 BP, aggregation at villages provided a way to effectively manage fisheries that are highly sensitive to environmental change. However, with the eventual collapse of oyster fisheries and subsequent rebound in environmental conditions ca. post-3800 BP, people dispersed from shell rings, and shifted to non-marine subsistence economies and other types of settlements. This study provides the most comprehensive evidence for correlations between large-scale environmental change and societal transformations on the Georgia coast during the Late Archaic period.