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Recent and Planned Developments of the Program OxCal
Abstract
OxCal is a widely used software package for the calibration of radiocarbon dates and the statistical analysis of ¹⁴ C and other chronological information. The program aims to make statistical methods easily available to researchers and students working in a range of different disciplines. This paper will look at the recent and planned developments of the package. The recent additions to the statistical methods are primarily aimed at providing more robust models, in particular through model averaging for deposition models and through different multiphase models. The paper will look at how these new models have been implemented and explore the implications for researchers who might benefit from their use. In addition, a new approach to the evaluation of marine reservoir offsets will be presented. As the quantity and complexity of chronological data increase, it is also important to have efficient methods for the visualization of such extensive data sets and methods for the presentation of spatial and geographical data embedded within planned future versions of OxCal will also be discussed.
... However, because of variations in the 14 C concentration in the atmosphere over time and space, the relationship between the calculated radiocarbon age and the "true" calendar age of a sample is complex. To account for these variations, sinusoidal calibration curves are regularly produced [41,42]. The calibration curve used currently in the Northern Hemisphere is IntCal20 [43]. ...
... Radiocarbon dating was conducted using AMS at the Artemis AMS Facility, Saclay, France [56]. Calendar dates were determined using the OxCal v.4.4.4 procedure [41,42,57] and calibrated at 95.4% probability using the IntCal20 calibration curve for the Northern Hemisphere [43], considering that marine products only contributed marginally to the individual's diet. ...
The estimation of the postmortem interval for skeletal remains is a crucial aspect of forensic anthropology. This paper illustrates the importance of radiocarbon analysis for establishing medico-legal significance and supporting forensic identification, through the analysis of three case studies for which the years of both birth and death were investigated. In Audresselles, Northern France, a partial skull was discovered with no contextual information or identity. Radiocarbon dating yielded an average calibrated calendar age of 4232 BCE (92.5% probability), indicating significant archaeological value but no forensic relevance. In the second case, skeletal remains were found in the flooded underground of a historical fort at Wimereux, Northern France, also with no identity. Radiocarbon dating based on the bomb-pulse curve indicated a calibrated date of death in 1962 CE (37.3% probability) or 1974–1975 CE (58.1% probability), both surpassing the French statute of limitations. Lastly, a skeleton with a suspected identity was discovered near Valenciennes, Northern France, and various biological tissues underwent radiocarbon dating. A bone sample suggested a calibrated date of death of 1998–2002 CE (84.6% probability), differing from a hair sample (2013–2018 CE, 83.3% probability) because of the slower bone tissue remodeling process. DNA analysis confirmed the person’s identity, reported missing a decade prior to the discovery of the remains, following the alignment of the radiocarbon results with the individual’s year of birth based on dental tissues and year of death. These case studies reveal that traditional radiocarbon dating and bomb-pulse dating are essential tools for estimating the postmortem interval, providing mutual benefits for archaeologists, forensic anthropologists, and the criminal justice system.
Key points
... Integrating trench logs and geochronology, we interpret individual surface-rupturing earthquakes and determine the amount of vertical displacement based on reconstructions of the stratigraphy. We model the paleoearthquake age constraints using Bayesian methods in the OxCal 4.4 sequence model (Lienkaemper and Ramsey, 2009;Ramsey, 2009;Ramsey and Lee, 2013;Reimer et al., 2020) to refine the uncertainties in the geochronology throughout the stratigraphy. By incorporating individual tephra ages, radiocarbon results, and stratigraphic order, we model our statistically preferred age probability density functions for paleoearthquakes and tephra deposition. ...
... ;Ramsey and Lee, 2013;Reimer et al., 2020). ...
Earthquake recurrence intervals, surface-rupture extents, and interactions between faults provide insight into how faults behave and are critical for seismic hazard mitigation and earthquake forecasting. Investigating the paleoseismology of spatially related faults can reveal strain distribution and whether faults rupture as a system or independently. Summer Lake basin, a graben in the northwestern Basin and Range with four active faults (three of which have prior paleoseismic investigations), provides an opportunity to investigate fault interactions. To expand the paleoseismic record, two trenches were excavated across the previously undocumented Thousand Springs fault, exposing a normal fault zone that offsets a sequence of deep- to shallow-water lake sediments, sand dunes containing reworked Mazama ash, and other Cascades-sourced tephra. Tephra units were correlated to known units by their physical characteristics, stratigraphic sequence, glass chemistry, and two new radiocarbon dates from the uppermost lake sediments. Using trench exposures, measured vertical separations through auguring, colluvial wedges, and extrapolated offsets based on a constant sedimentation rate, we identified at least five surface-rupturing earthquakes with a total offset of 3.4 + 2/−1 m in the past ∼65 ka. The oldest event (EH5) occurred at 63.8 ± 1.5 ka, event horizon 4 at 36.2 ± 12.7 ka (which could be more than one event), and event horizon 3 at 24.6 ± 0.3 ka. Event horizon 2, a warping event at our site, is likely more than one event and occurred between 7.5 and 10 ka; and the most recent event (EH1+), most likely more than one event, occurred between 3.3 and 7.7 ka. Several events correlate, within error, with events on other faults in the Summer Lake basin, suggesting that (1) the faults generally rupture together as a system, (2) the most recent earthquake may have ruptured all faults in the region, and (3) fault rupture is influenced by the rapid regression of Lake Chewaucan (∼13 ka).
... For data interpretation, age-depth modeling was applied with the use of the OxCal v 4.2.4. [61] calibration program. The 210 Pb technique of peat dating was applied for the upper part of the core P1 up to 29 cm in depth. ...
Sustainable soil resource management requires detailed knowledge of soil pollution sources and their share in total pollution level. Spatial pollution caused by the total cumulative atmospheric deposition remains largely unknown, as the biggest pollutant emissions occurred in XIX/XX centuries. The use of ombrotrophic peatlands that are specific isolated ecosystems fed only through atmospheric deposition may serve as its natural archives. Accumulation of Cd and Pb from atmospheric deposition in undisturbed soil layers in relation to their total deposited cumulative loads recorded in the ombrotrophic peat bog was exemplified in the Izera Mountains, an area historically heavily affected with the transboundary long-range transmission of pollutants from Germany, the Czech Republic, and Poland. Balance of deposited Cd and Pb loads in soil in relation to the total cumulative deposition determined from peat records showed 30% depletion of Cd load in the soil profile due to washout of mobile phases, while that of Pb practically did not decline. The deposited element accumulation and release/depletion in undisturbed soil profiles can thus be quantified in relation to the total cumulative load of atmospheric deposition. This shows a new prospective application of peat bog records as monitors of total cumulative loads of trace elements supplied to soils from atmospheric deposition.
... A mass movement deposit dated to ∼2030 cal yr BP precludes a continuous varve count tied to the surface. For sediments older than this deposit, an age model was constructed in OxCal v4.3 using a P-sequence (Bronk Ramsey, 2008, 2009Bronk Ramsey & Lee, 2013). The Psequence input includes 66 radiocarbon ages and two segments of floating varve counts (∼4,640 and ∼600 varves, respectively). ...
Paleoclimate data provide important information about the character of natural climate variability. However, records with sufficient length and resolution to resolve high‐frequency (decadal‐scale) variability across the Holocene are scarce. We present a 10,800‐year reconstruction of spring and summer temperature at three‐year resolution based on biochemical varves from Lake Żabińskie, Poland. The reconstruction is based on Ca/Ti ratio, which are significantly correlated with instrumental spring and summer temperature spanning 240 years. Major climate events of the Holocene period are represented in the reconstruction, including the Holocene Thermal Maximum, 8.2 ka Event, Medieval Climate Anomaly, and Little Ice Age. A low‐frequency 8,000‐year decreasing trend in warm‐season temperatures is driven by declining summer insolation. Temperature variability is highest during the early Holocene, likely related to warmer and drier conditions. The rate of warming during the past 90 years is extremely unusual, if not unprecedented for the Holocene, based on our reconstruction.
... The sample of oak wood taken from the back of the mounting panel gave a conventional 14 C age of 310 ±30 BP (Poz-151,973). Calibration of these ages ( Fig. 1 d) indicates the sample most probably (with 95.4 % confidence) descend from intervals 14 90-164 9 CE [41][42][43][44]. This date is distinctly ( ≥200 years) older than the time when the painting was mounted to the wooden panel, approximately 20 years after its creation by Van Gogh. ...
... For data interpretation, age-depth modeling was applied with the use of OxCal v 4.2.4. [51] calibration program. The 210Pb technique of peat dating was applied for the upper part of the core P1 up to 29 cm depth. ...
Sustainable soil resource management requires detailed knowledge of soil pollution sources and their share in total pollution level. Spatial pollution caused by the total cumulative atmospheric deposition remains largely unknown, as the biggest pollutant emissions occurred in XIX/XX centuries. The use of ombrotrophic peatlands that are specific isolated ecosystems fed only through atmospheric deposition may serve as its natural archives. Accumulation of Cd and Pb from atmospheric deposition in undisturbed soil layers in relation to their total deposited cumulative loads recorded in the ombrotrophic peat bog was exemplified in the Izera Mountains. area historically heavily affected with the transboundary long-range transmission of pollutants from Germany, Czech Republic and Poland. Balance of deposited Cd and Pb loads in soil in relation to the total cumulative deposition determined from peat records, showed 30% depletion of Cd load in the soil profile due to washout of mobile phases, while that of Pb practically did not decline. The deposited element accumulation and release/depletion in undisturbed soil profiles can thus be quantified in relation to the total cumulative load of atmospheric deposition. This shows a new prospective application of peat bog records as monitors of total cumulative loads of trace elements supplied to soils from atmospheric deposition.
... A radiocarbon date was obtained from a peat sample which underwent alkali-acid-alkali pretreatment before AMS counting. The conventional 14 C age was calibrated using OxCal 4.4 (Ramsey and Lee, 2013), with the IntCal 20 curve (Reimer et al., 2013; see Table 2). ...
Historical maps with high degree of accuracy permit quantitative reconstructions of past land use and land cover (LULC), crucial to assess the impact of human activities on landscape evolution. After georeferencing in a modern reference system, the Carta del Ferrarese commissioned by Napoleon Bonaparte and completed in 1814, has been used to quantify the changes in LULC, occurred in the last two centuries in the Po delta plain. The map depicts a palaeo-landscape dominated by wetlands (49 % of the study area) and agricultural areas (41 %), whereas forests appear already largely depleted (5 %). The Piantata Padana, a traditional agroforestry system with live trees used to support grapevines, is dominant (62 % of the agricultural areas). The comparison with the 2014 LULC map highlights a dramatic reduction (85 %) of wetland areas and the replacement of the Piantata Padana with bare arable lands, with the consequent removal of 4–40 million trees. Soils of areas formerly occupied by wetlands show high organic-carbon content, highlighting the potential of humid areas in carbon sequestration. Land reclaiming, prompted by the introduction of steam pumps, favoured the economic development of the area, but concurred to CO2 emissions through the oxidation of soil organic substances, energy consumption from pumping stations, and the extensive use of hydrocarbon fuels in agriculture. Although urbanisation is limited in the Po delta plain, this area appears nowadays largely shaped by human activities, with the dominance of lands devoted to agriculture, dissected by a dense network of draining channels. The landscape changes recorded in the last two centuries in the Po coastal plain have been uniquely driven by human activities, like in several coastal plains worldwide.
... The 14 C concentration in pure graphite was measured with a 1MV AMS system (HVEE) and 14 C ages based on the 14 C/ 12 C and 13 C/ 12 C ratios were calculated following LEMA protocols (Solís et al. 2014). OxCal v 4.4.4 program (Bronk Ramsey 2009;Ramsey and Lee 2013) with IntCal20 curve (Reimer et al. 2020) was used to obtain calibrated ages (BC/AD) with confidence limits of 95%. A chronological modeling was undertaken using the program OxCal 4.4.4. ...
Despite chronicles from the 16th century describing fertile alluvial plains and densely populated wetlands, archaeology in western Mexico has been little studied. The Directorate of Archaeological Salvage (DSA) of National Institute of Anthropology and History (INAH) has initiated a study of two sites in Costa Canuva, at the southern part of Nayarit state: Becerros and Naranjos. Thirty charcoal and shell samples were radiocarbon ( ¹⁴ C) dated to determine occupation history. A Bayesian approach was used to build a chronological modeling from charcoal samples. Charcoal and shell samples found in the same context allowed us to calculate the ΔR values of marine offset for this period. In general, the archaeological sites of this area are divided into three major periods: Formative, Classic, and Postclassic. The ¹⁴ C dating of Becerros recovered materials provided a chronological framework for the site’s occupation, from cal AD 169–1025, corroborating the ceramic studies in the sense that human settlement activities date from the Formative (300 BC–AD 600) to the Early Postclassic (AD 900–1200). Naranjos started in the Classic period and reached its occupancy peak in the Late Classic. The site’s occupation may have persisted for at least two centuries after the conquest of the Altiplano in 1521. The comparison of charcoal dates and associated shell samples from the Naranjos Unit gave a probability distribution for ΔR, that ranged from 118.5 to 199.5 with a mean value of 159 ± 4, slightly higher than other values obtained at nearby sites.
... The stratigraphic sequence excavated covers a time span of more than 10,000 years from 55 to 43 Kya. Two dates define the chronological limits: the first is a 14 C date, from the bottom of SU1 (Ramsey & Lee, 2013). The second derives from the identification of the tephra layer (SU14) as Mount Epomeo green tuff (Isola di Ischia), dated to about 55 ka BP (Allen et al., 2000;Tomlinson et al., 2014;Wulf et al., 2004). ...
In the Italian peninsula, the Late Middle Paleolithic exhibits significant technological diversity, featuring blades, points, and bladelets. Assemblages displaying these distinctive characteristics have, in some cases, been labeled as Musteriano evoluto or Evolved Mousterian, and they are interpreted as contributing to the technological and typological variability within the Middle Paleolithic. In this study, we report the results of a detailed technological analysis of the lithics recovered from the latest layers preserved at Riparo l’Oscurusciuto (SU1 to SU3) in southern Italy. These layers were previously attributed to the Late Mousterian based on their chronological age and a preliminary techno/typological analysis of a small number of artifacts. Our comprehensive analysis of entire assemblages reveals the presence of original technological features, including blades, bladelets, and specific production of micro-points on flake cores. Some of these technological traits are comparable to those recently described at Grotte Mandrin in south-eastern France, which have been attributed to an early phase of the Initial Upper Paleolithic and associated with one modern human tooth. The study confirms the variability of the Late Middle Paleolithic in southern Italy and emphasizes the necessity to reassess it considering recent theories on the earlier arrival of Homo sapiens in Europe and their potential interaction with local populations.
... The conventional 14 C ages in calendar years are calibrated using the OxCal4 program (Ramsey and Lee 2013) package and the Intcal20 Northern Hemisphere Radiocarbon Age Calibration Curve (Reimer et al. 2020). ...
The construction history and subsequent usage of burial mounds are an important testimony for socio-economic transformation in prehistoric societies. The Baalberge-Schneiderberg burial mound, subject of the presented study, falls in this category as it is considered as an important monument that indicates the emergence of early social stratification during the Chalcolithic period in central Europe. This hypothesis relies on the chronological development of the burial mound, which is not fully understood until now. Therefore, a reconstruction of the complex stratigraphy of the burial mound including construction phases and later alterations is highly relevant for archaeological research, but the required excavations would be onerous and inconsistent with preservation efforts. In this paper, we demonstrate that non-invasive geophysical prospection, especially seismic sounding with shear and Love waves, is suitable to obtain the required stratigraphic information, if seismic full waveform inversion (FWI) and reflection imaging are applied. Complementary information on the preservation state of the mound is obtained through Electrical Resistivity Tomography (ERT) and Electromagnetic Induction (EMI) measurements. To support the seismic and geoe-lectric results, we utilize Dynamic Testing (DynP), geoarchaeological corings, C-14 Dating and archaeological records. Our investigations reveal two construction phases of the Baalberge-Schneiderberg mound. The C-14 Dating yields dates for the older burial mound that are contemporary to the Chalcolithic Baalberge group (4000-3400 bc). During the Early Bronze Age (EBA), the mound was enlarged to its final size by people of the Aunjetitz/Únětice society (2300-1600 bc). However, both seismic and geoelectric depth sections show an extensive disturbance of the original stratigraphy due to former excavations. For this reason, the exact shape of the older burial mound cannot be determined exactly. Based on our data, we estimate that its height was below 2 m. In consequence, the original Baalberge burial mound was less monumental as until now assumed, which potentially prompting a revision of its significance as indicator for social differentiation.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
... The interpolated age model for the stalagmite central growth axis was produced using the OxCal version 4.4 Poisson-process deposition model, with the stalagmite vertical growth rate constrained using model inputs k 0 = 0.1 mm −1 and log 10 (k/k 0 ) = U (−2, 2) (Ramsey, 2008(Ramsey, , 2009Ramsey and Lee, 2013). Because sample pits in this study were drilled off the central axis, visible laminae were tracked to connect the sample pit locations to the central growth axis to determine the mean age range and 95 % confidence age range of the sample pits. ...
Speleothems (cave stalagmites) contain inorganic and organic substances that can be used to infer past changes in local and regional paleoenvironmental conditions. Specific biomarkers can be employed to elucidate the history of past fires, caused by interactions among climate, regional hydrology, vegetation, humans, and fire activity. We conducted a simple solid–liquid extraction on pulverised carbonate samples to prepare them for analysis of 16 polycyclic aromatic hydrocarbons (PAHs) and three monosaccharide anhydrides (MAs). The preparation method requires only small samples (0.5–1.0 g); PAHs and MAs were measured by GC–MS and LC–HILIC–MS, respectively. Detection limits range from 0.05–2.1 ng for PAHs and 0.01–0.1 ng for MAs. We applied the method to 10 samples from a ∼ 400-year-old stalagmite from Cenote Ch'en Mul, at Mayapan (Mexico), the largest Postclassic Maya capital of the Yucatán Peninsula. We found a strong correlation (r = 0.75, p < 0.05) between the major MA (levoglucosan) and non-alkylated PAHs (Σ15). We investigated multiple diagnostic PAH and MA ratios and found that although not all were applicable as paleo-fire proxies, ratios that combine PAHs with MAs are promising tools for identifying different fire regimes and inferring the type of fuel burned. In the 1950s and 1960s, levoglucosan and Σ15 concentrations roughly doubled compared to other times in the last 400 years, suggesting greater fire activity at Mayapan during these two decades. The higher concentrations of fire markers may have been a consequence of land clearance at the site and exploration of the cave by Carnegie Institution archaeologists.
... The IntCal20 curve and Libby half-life of 5,568 years were used in the tree-ring calculation of all dates 43 . Calibration was carried out using the OxCal 4.4 program 44 . All ages are reported as cal bp relative to 1,950 CE. ...
The onset of sedentism on the Tibetan Plateau is often presumed to be associated with the dispersal of agriculture or farmers from archaeological sites located in the low elevation margins of the plateau. Previous studies of the plateau assumed that all foragers were probably mobile, but few systematic excavations at forager sites have been conducted to inform us about their settlement patterns. Here we report the world’s highest elevation sedentary way of living exhibited by the Mabu Co site at 4,446 metres above sea level, deep in the interior of the Tibetan Plateau 4,400–4,000 years ago. Our interdisciplinary study indicates that the site was occupied by Indigenous inhabitants of the plateau, representing the earliest known DNA evidence of foragers who predominantly harbour the southern plateau ancestry. The evidence shows that they had a sedentary lifestyle primarily supported by fishing at nearby lakes, supplemented by mammal and bird hunting, as well as small-scale exchanges of millet and rice crops.
... Ages are reported with 2σ errors in years BP. A time-depth model was created in OxCal 4.4 using the Bayesian approach, with a 'k' parameter of 0.2 mm −1 (Bronk Ramsey, 2008;Bronk Ramsey, 2009;Bronk Ramsey & Lee, 2013). This model allows for the combination of U-Th ages in a probabilistic nature even if there are overlapping errors or age reversals. ...
Marine Isotope Stage (MIS) 5c, between~106 000 and~93 000 years ago, represents an important warm period in which the current anthropogenic warming can be contextualized. Although viewed as a pronounced interstadial, its climate expression is regionally disparate, with different regions on Earth showing evidence of either cooler or warmer conditions than modern-day. It is therefore important to expand temperature reconstructions to different regions on Earth to gain a better picture of climate dynamics during MIS 5c. In Alaska, there are no quantitative temperature reconstructions for MIS 5c, limiting our knowledge of temperature changes in this climatically sensitive high-latitude region. Here, we fill this gap by providing the first quantitative temperature estimates from MIS 5c in Alaska using hydrogen isotopes of fluid inclusions in precisely dated speleothems. We find that regional temperatures during MIS 5c were within error of the modern-day reference period (1929-1989 CE) temperatures, possibly representing the most recent time period that regional temperatures were as high as modern-day.
... Petersburg State University) and reported in Semikolennykh et al. (2018). The conventional 14 C ages were calibrated (2-sigma standard deviation) using the OxCal 4.4 program (Bronk Ramsey and Lee, 2013) with the IntCal20 calibration data set (Reimer et al., 2020). The paper presents conventional 14 C (BP) and calibrated ages (cal BP). ...
The Kerch Strait has periodically connected to the Black, Azov, and Caspian seas throughout its Late Quaternary history. The strait's deposits reflect the changes in the natural environment of the entire Ponto-Caspian region, which are a response to global climate change. Several studies have been done on the region's stratigraphy, biostratigraphy, geomorphology, and paleogeography. However, most of the current knowledge about the paleogeography of the area is based on the analysis of empirical data collected more than 25 years ago, and due to the lack of detailed geochronological studies, many palaeogeographical problems remain unresolved. This paper presents a reconstruction of environmental change in the Kerch Strait during the Late Quaternary. The reconstruction is based on the results of a comprehensive study of the sedimentary sequences in the Kerch Strait carried out by the author and colleagues over the past ten years. The study examines the deposits of two stratotype sections of the Karangatian (Eemian) transgression and the four boreholes' sections in Tuzla Island in the central part of the strait. A biostratigraphic division of the Upper Quaternary deposits of the Kerch Strait was carried out based on a malacofaunal study. Mollusc assemblages corresponding to various paleogeographic stages of development were identified, and their paleoecological characteristics were described. Luminescence and radiocarbon ages made it possible to determine the time intervals of established paleogeographic stages in the strait's history. Detailed luminescence dating of the Karangatian transgression sediments of the Eltigen and Tuzla stratotype sections has been carried out for the first time. Six main stages in the Kerch Strait natural environment development were established in the Late Quaternary and correlated with global and regional climatic events: Karangatian, with three stages (MIS 5e-c); Tar-khankutian (MIS 5a); Post-Karangatian (MIS 4); Surozh (MIS 3); Neoeuxinian, with two stages (MIS 2); and Chernomorian (MIS 1). Two episodes of the Caspian waters flowing through the Kerch Strait into the Black Sea were identified in MIS 5c and at the end of MIS 2.
... A Bayesian age-depth model for FW 18/2 ( Figure 2) was constructed using the results of R_combine function for the five basal ages and the four other radiocarbon age determinations from core FW18/2 using a 'P_sequence deposition model' (Bronk Ramsey 2008;Bronk Ramsey and Lee 2013). The 14 C ages were calibrated using the SHCal20 calibration curve (Hogg et al. 2020) and postbomb SH zone 1-2 calibration curve (Hua et al. 2022;Hogg et al. 2020). ...
... In order to provide more precise ages for the individual sites, as well as refined chronology for the relationships between sites, radiocarbon dating and Bayesian chronological modelling was performed [106,107]. Organic samples chosen from distinct archaeological contexts were collected for radiocarbon dating to, as reliably as possible, represent the age of formation and/or deposition. For cemeteries demonstrating multiple phases, samples for dating were acquired from different burials pre-judged by typology to better span the whole chronology of the cemetery. ...
Urbanization is one of the milestones in the development of human society. Many regions in the southern parts of ‘the old world’ demonstrating an early emergence of agriculture also witnessed the flourishing of some of the earliest cities. Recent, yet still sparse, archaeological evidence appears to indicate a relatively later time for early urbanism in central Eurasia. However, given its vital geographic location and cultural nexus between East and West, more attention should be paid to the sedentary communities and their cities in oases amid the vast droughty desert, particularly in light of the rapidly increasing number of publications on early pastoralism and related communication routes along mountain chains and rivers. This study reveals the trajectory of urbanization and its role in the establishment of an exchange network in Xinjiang’s oasis region via reconstruction of the chronological sequence of the local societal history of the Baiyang River Basin along the southern piedmont of the Eastern Tianshan Mountains. A thorough archaeological investigation and refined radiocarbon dating programme was carried out and coupled with information from historical documentation within a Bayesian statistical framework. The results indicate three pulses of local urbanization during: the Early Iron Age, Tang–Yuan period, and Qing Dynasty, respectively. Combining this with evidence from other parts of Xinjiang, we re-evaluate the role of oasis urbanism in the promotion of trans-regional exchange.
... KDE and one-phase Bayesian start/end date modelling [15][16][17] were performed in OxCal v4.4.2 [ 13 ] using the IntCal20 calibration curve [ 14 ] to summarize the radiocarbon dates and obtain a refinement of the TRB habitus at Kałdus. ...
This dataset compiles radiocarbon dates received for botanical macroremains and animal bones from domestic and ritual pits and human graves unearthed during excavations at the archaeological site of Kałdus (Poland) that can be related to the Funnel Beaker culture (TRB). Prior to radiocarbon dating by accelerator mass spectrometry (AMS), plant macroremains were checked against diagnostic attributes of species identification by standard paleobotanical analysis. The dataset contains already published ( n = 4) and new ( n = 10) radiocarbon dates that were used to establish the absolute chronology of the TRB habitus at Kałdus and its diachronic spatial organization. This dataset serves as an archive for future studies focusing on the TRB settlement pattern and organization in the region of modern Poland. It also has a utility to be reused in archaeological and chronological research on the movement of copper metalwork and the gradual spread of human cremation rite in the region.
... The level of fluctuation in the deposition process is controlled by a parameter called k. A variable k parameter was chosen to find the best fitting model for our data (Ramsey & Lee 2013). From the modelled age-depth plot, sedimentation rates were calculated by dividing the depth increments between samples by their age differences. ...
Lake Paravani, located on the volcanic Javakheti Plateau in the central part of the Lesser Caucasus at 2073 m a.s.l., forms a unique geo‐bio‐archive for palaeoenvironmental reconstructions in this remote region. Based on sediment cores from the southwestern part of the lake we expand the existing palynological and sedimentological records beyond the Last Glacial Maximum (LGM). For the first time, it is possible to reconstruct the palaeoenvironment in this part of the Lesser Caucasus back to c. 28 cal. ka BP. Our study shows that until 16 cal. ka BP glacial conditions dominated (Phase I) in the region; there is, however, proof that the lake already existed during the LGM. In the following transitional Phase II from 16 until 6 cal. ka BP, cold and arid conditions with sparse steppe vegetation and a lowered lake level prevailed. Around 10 cal. ka BP, tree pollen started to expand while herbaceous pollen, especially Chenopodiaceae, declined. In Phase III, since 6 cal. ka BP, mixed forest probably represented the Holocene climatic optimum. Fluctuating lake levels indicate shifting climatic conditions. The minor changes of arboreal pollen hin the uppermost part of Phase II may be an indication of human activity. The more humid, vegetation‐rich environment and mild climate around 4.5–2 cal. ka BP correlate with the expansion of the Late Bronze Age settlements in this area (from ~3.5 cal. ka BP/~1.5 ka BC). The proliferation of sites on the plateau, along with even higher‐altitude sites possibly dating to the same period, may indicate that this climate amelioration played an important role in enabling more sustained human occupation. The results extend the record on Lake Paravani by several millennia beyond the LGM and complement the palaeo‐lake reconstructions of the wider region, e.g. at Lake Van (Türkiye) or Lake Sevan (Armenia).
... These additional dated specimens included two mandibles of red deer from Arbreda for which intra-individual enamel sampling was conducted. The results were calibrated at 2 sigmas based on the IntCal20 curve (Reimer et al., 2020) and using OxCal v. 4.4 interface (Ramsey and Lee, 2013). The taxonomic identification of a few faunal samples was confirmed by submitting collagen subsamples to fingerprinting by Zooarchaeological by Mass Spectrometry (ZooMS) method (Buckley et al., 2009). ...
... Here, we updated the Tustumena Lake age-depth model of de Fontaine et al. (2007) as a P_Sequence deposition model (Bronk Ramsey, 2008;Ramsey and Lee, 2013) with radiocarbon ages calibrated using the IntCal20 curve (Reimer et al., 2020). This gives an age estimate of ca. ...
... Bayesian statistical program (Bronk Ramsey, 2009a). A P_Sequence depositional model was constructed using a General_Outlier model and a variable k parameter (Bronk Ramsey, 2008, 2009bBronk Ramsey and Lee, 2013). One radiocarbon date (UCIAMS-219310) was removed from the age-depth model as it caused a substantial age reversal and thus was considered unreliable (Table A1). ...
When tracing vegetation dynamics over long timescales, obtaining enough floristic information to gain a detailed understanding of past communities and their transitions can be challenging. The first high-resolution sedimentary DNA (sedaDNA) metabarcoding record from lake sediments in Alaska—reported here—covers nearly 15,000 years of change. It shows in unprecedented detail the composition of late-Pleistocene “steppe-tundra” vegetation of ice-free Alaska, part of an intriguing late-Quaternary “no-analogue” biome, and it covers the subsequent changes that led to the development of modern spruce-dominated boreal forest. The site (Chisholm Lake) lies close to key archaeological sites, and the record throws new light on the landscape and resources available to early humans. Initially, vegetation was dominated by forbs found in modern tundra and/or subarctic steppe vegetation (e.g., Potentilla, Draba, Eritrichium, Anemone patens), and graminoids (e.g., Bromus pumpellianus, Festuca, Calamagrostis, Puccinellia), with Salix the only prominent woody taxon. Predominantly xeric, warm-to-cold habitats are indicated, and we explain the mixed ecological preferences of the fossil assemblages as a topo-mosaic strongly affected by insolation load. At ca. 14,500 cal yr BP (calendar years before C.E. 1950), about the same time as well documented human arrivals and coincident with an increase in effective moisture, Betula expanded. Graminoids became less abundant, but many open-ground forb taxa persisted. This woody-herbaceous mosaic is compatible with the observed persistence of Pleistocene megafaunal species (animals weighing ≥44 kg)—important resources for early humans. The greatest taxonomic turnover, marking a transition to regional woodland and a further moisture increase, began ca. 11,000 cal yr BP when Populus expanded, along with new shrub taxa (e.g., Shepherdia, Eleagnus, Rubus, Viburnum). Picea then expanded ca. 9500 cal yr BP, along with shrub and forb taxa typical of evergreen boreal woodland (e.g., Spiraea, Cornus, Linnaea). We found no evidence for Picea in the late Pleistocene, however. Most taxa present today were established by ca. 5000 cal yr BP after almost complete taxonomic turnover since the start of the record (though Larix appeared only at ca. 1500 cal yr BP). Prominent fluctuations in aquatic communities ca. 14,000–9,500 cal yr BP are probably related to lake-level fluctuations prior to the lake reaching its high, near-modern depth ca. 8,000 cal yr BP.
This book forms part of contemporary research on the interaction between migratory early farmers of Anatolian origin and European hunter-gatherers. In southern Eastern Europe, these two ways of life coexisted for thousands of years, resulting in a wide variety of configurations and patterns. Therefore, this part of the prehistory of southern Eastern Europe is of general European importance, providing comparative material for the study of Neolithisation and offering a different perspective to illuminate the possible variants of historical development and better identify the social structures behind the differences.
The population history of the northern coastal Chinese is largely unknown due to the lack of ancient human genomes from the Neolithic to historical periods. In this study, we reported 14 newly generated ancient genomes from Linzi, one of China’s densely populated and economically prosperous cities from the Zhou to Han Dynasties. The ancient samples in this study were dated to the Warring States period to the Eastern Han Dynasty (∼ 2000 B.P). We found the samples derived all their ancestry from Late Bronze Age to Iron Age Middle Yellow River farmers rather than local Neolithic populations. They were genetically homogeneous with present-day Han Chinese of Shandong, suggesting two thousand years of genetic stability. Our results highlight the role of the eastward migration of Yellow River farmers in the Central Plain to northern coastal China in forming the present-day genetic structure of Han Chinese.
While a clear human presence may be recognised in the Andes by 12 000-11 000 cal BP, most archaeological research has focused on occupation of the Andean highlands. To understand the initial occupation of inland areas of South America, the authors consider regional connections and spatial exploitation strategies of hunter-gatherers highlighted in a recent survey of Andean sites. Focusing on north-central Chile, artefacts and radiocarbon dates from three rock shelters suggest sporadic and brief occupation during the Terminal Pleistocene-Early Holocene. Co-occurrence of marine and montane resources, the authors argue, demonstrates a strategy of high mobility and local adaptation in early Andean occupation , using rock shelters as landmarks to navigate and learn new landscapes.
The Middle and Late Pleistocene were characterized by high-amplitude climate and sea-level oscillations that deeply influenced the evolution of alluvial and coastal systems worldwide. Through the correlation of 43 cores and 168 well data, with the aid of pollen, meiofauna, 14 C, ESR and IRSL data, this work provides a detailed reconstruction of the Middle Pleistocene to Holocene stratigraphy of the Po Basin and explores the sedimentary response of the Po-Adriatic alluvial-coastal system to glacio-eustatic oscillations and other concomitant forcing factors. The Middle Pleistocene to Holocene sedimentary succession of the Po Basin is composed of alluvial, paralic, coastal and shallow-marine facies associations arranged in an overall shallowing-upward trend. This general trend is punctuated by the rhythmical alternation of progradationally stacked coastal wedges with thick alluvial deposits. At landward locations, where the coastal facies wedge out, the depositional cyclicity records alternating paralic and alluvial facies associations. The overall shallowing-upward trend documents the longer-term, progressive filling of the basin driven by high sediment supply which overcame the rate of creation of accommodation induced by subsidence. The cyclic arrangement of facies, paralleled by rhythmical changes in vegetation, reflects Milankovitch-scale, glacio-eustatic oscillations in the 100 ka band. Increasing subsidence towards the sea and the activity of selected sectors of the buried Apennine thrust front, might have enhanced the seaward migration of coastal wedges. This study provides clues on the sedimentary response of a low-gradient coastal system to dramatic climatic and eustatic changes. The model of basin evolution presented here may help predict the environmental modifications of coastal areas in near future scenarios of climate and sea-level change.
Background The "Archeology of the Light" (A-Light) project aims to improve our knowledge of paleolithic cave activities through an interdisciplinary methodology applied to rarely-studied remains: the residues of Paleolithic light from lamps, fireplaces and torches (specially, charcoal and soot). Methods The methodology includes different stages such as: 1. Work in caves and sampling, 2 Laboratory analyses (multi-analytical approach adapted to the type of combustion residue analysed, including Anthracology, C14 dating, Bayesian analysis, SEM-EDX, TEM.EDX, Raman…), 3. Ethnographic review of firelight, 4. Experimental reproduction and monitoring of Palaeolithic firelight. Results This approach contributes multifaceted data about the Paleolithic activities inside the caves (lighting systems selected, fuel used, chronology and intensity of visits, paleo-paths...). Besides, experimental reproductions have enabled evaluation of their lighting potential, and provide essential information for research the visibility and the accessibility of Rock Art from GIS, and allow to more realistic virtual simulation. Conclusions In short, these data demonstrate that the Archaeology of the Light is here to stay and that it is an essential approach for a holistic understanding of Palaeolithic caves.
Lagore, Co. Meath, has long been a type-site for artificial lake dwellings known as crannogs since excavation in the 1930s by the Harvard Expedition. Renowned for rich finds and documented as the seat of the kings of Southern Brega (8th and 10th centuries AD), alongside the high-status and royal functions of the site, it is now widely recognised that Lagore had a long history of activity stretching back into later prehistory with evidence of deposition of human and animal remains, and metalwork of the Bronze and Iron Ages, and early medieval period. Nonetheless, a poor stratigraphic and archival record has engendered much debate about the timings and tempos of its origins, and the longer-term settlement history of the lough. This paper utilises multi-proxy analysis (Palynology, Geochemistry, Loss-on-Ignition (LOI), Colour, Fourier-transform-infrared-spectroscopy (FTIR) and Attenuated-total-reflectance (ATR)) to provide a deeper chronological understanding of land-use and occupation at Lagore. The most significant findings include the likelihood of local settlement (strong farming and parasite signals) well before the main phases of crannog construction, from at least ∼470 BC; a significant lull in population during the early-mid 5th century AD; a gradual economic recovery from ∼AD 555–620, which coincides with the main phase of crannog construction (based on geochemical and other lithological results); and a slightly later transition into a Royal residence from AD 620, marked by both intensification and diversification of agriculture (wheat/oats, rye, flax and cannabis) and a potential iron working signal
Background
The mule deer (Odocoileus hemionus) and its two distinct black-tailed deer (BTD) subspecies, Sitka and Columbian BTD, have a complex history in North America involving survival in Last Glacial Maximum (LGM) refugia, postglacial expansion along the Pacific Northwest Coast, evidence for incomplete lineage sorting and recent introgression between subspecies. Moreover, the differentiation process of the two black-tailed deer subspecies is poorly understood and could have been a consequence of the LGM. As such, they provide an exemplary system to explore patterns of population dynamics in response to climate change.
Results
Here we analyzed genome-scale data from samples spanning the last 13,500 years to explore the evolutionary history of Sitka BTD in Southeast Alaska. Deer samples from Southeast Alaska older than 8,500 years ago shared a mitochondrial haplotype with mule deer, whereas samples younger than 6,000 years have the modern Sitka BTD haplotype. Discordantly, nuclear genomic data confirmed that all ancient individuals from Southeast Alaska are closely related to modern Sitka BTD, although the older group also shared ancestry with mule deer. Modern samples from Vancouver Island share more alleles with modern Sitka BTD than Columbian BTD. Our results support that they survived in the same glacial refugium south of the Cordilleran ice sheet, along today’s Oregon coast.
Conclusion
The uneven deglaciation along the Northwest Pacific Coast following the LGM may have created temporary post-glacial refugia, or “stepping stones”, along the British Columbia Coast. Such dispersal, associated with genetic drift and isolation by distance, likely led to the emergence of the BTD subspecies, as well as the low genetic diversity observed in modern Sitka BTD.
The Second International Mortar Dating Intercomparison Study (MODIS2) took place in 2020. Three mortar samples from different sites and chronologies were distributed among various research groups in form of bulk mortar and grain fraction smaller than 150 µm. This is the first time the Zagreb Radiocarbon Laboratory, with support of the Center of Applied Isotope Studies, University of Georgia, took part in the international mortar intercomparison. The initial approach of the Laboratory to mortar dating was to separate 32–63 µm grain fraction and collect three CO 2 gas portions by sequential dissolution with acid. After checking the ¹⁴ C date trends of the gas portions, which should be ascending with later fractions, the one for the first and shortest gas portion was reported as the age of the mortar. However, the first gas portion might not be true age of the mortar, since it still might contain some “dead” carbon. Therefore, data extrapolation from the first two initial CO 2 portions was also conducted on the results, but not reported to the intercomparison. Though in general, all the intercomparison reported dates fit the expected historical ages, for one sample, the extrapolated result showed a better match to the historical data.
Understanding the temperature evolution during the Holocene is crucial for future climate projections. However, a puzzling discrepancy between climate models simulating a warming trend during the second half of the Holocene parallel to the rise in atmospheric CO 2 concentrations and proxy data suggesting cooling during this period – known as the Holocene temperature conundrum – limits our understanding of how climate will evolve in the future. To solve this conundrum, the inclusion of quantitative paleotemperature records from high-latitude sites, which are extremely rare, is essential. Here, we use the hydrogen isotopic composition of fluid inclusions in speleothems from southeastern Alaska to create a quantitative temperature reconstruction of the entire Holocene. We show that the temperature in southeastern Alaska followed CO 2 , in agreement with modeling results. Because our data show no proxy-model bias, they support a seasonal proxy bias to account for the Holocene temperature conundrum.
A new series of 22 radiocarbon dates provides new insights on the origin and distribution of the Early Trypillian archaeological culture in modern-day Moldova and Ukraine. The paper presents data from the sites of preceding groups (5 dates), highlighting gaps in the agricultural settlement of the region, dates related to the Early Trypillia directly (14 dates) and dates from the ceramic hunter-gatherers' sites that yielded some Early Trypillian pottery (3 dates). The results indicate that the expansion of Early Trypillia into Moldovan and Ukrainian forest-steppe took place during 47-45th centuries BCE and it was a relatively fast colonization likely spanning only 3-5 generations.
The Kastro peninsula constitutes the extension towards the West of Myrina, the Lemnos capital, on the western coast of the island, in the North Aegean Sea. The ongoing research project on rock-cut features and rock-art of this complex site included a five-year (2002-2007) subsurface investigation, during which, among other mobile finds, charcoal and seashell samples were also collected, associated in situ to rock-cut features. Subsequently, in an attempt to bring about information on the dating of the rock-cut site, an investigation based on 14 C has also been undertaken. Therefore, the purpose of the present paper is the AMS dating of the unearthed anthropogenic deposits and the calculation of the regional marine reservoir effect during the end of the Late Bronze Age. Our results show that the age of the deposits is spanning from the 13th century BC till the 6th century AD. Moreover, the 14 C ages of two pairs of charcoal-seashell samples showed that the mean marine reservoir age R(t) in this region from the 13th to the 10th centuries BC is 175 ± 59 14 C yrs and the mean local sea surface reservoir deviation ΔR is found to be-288 ± 108 14 C yrs (within 1σ).
Catastrophic sediment overloading of mountain streams in response to coseismic landsliding causes river systems to fundamentally reorganize their morphology and sediment transporting characteristics, influencing sediment yields, bedrock incision, and the coupling between erosion and tectonics. A sequence of 13 airborne LiDAR surveys of an alpine tributary of the Hāpuku River, New Zealand, reveals patterns of sediment mass balance change over 5 years following delivery of 6.6 million cubic meters of landslide debris during the 2016 magnitude 7.8 Kaikōura earthquake. The surveys reveal how mountain river systems modulate catastrophic sediment deliveries to their lower reaches through sediment storage, evolution of channel morphology, and armoring of the bed. Variations in valley width contribute to the delay and diffusion of the seismically induced disturbance “wave” as it moves across river process domains. The landslide sediment train remnants may persist for longer than the return time of their triggering mechanism, leading to a long-lived hiatus in bedrock incision in this tectonically active mountain catchment.
El sitio Laguna del Indio se localiza en proximidades de la laguna homónima (partido de Coronel Suárez, provincia de Buenos Aires). Los análisis realizados sugieren que el sitio habría funcionado como un campamento residencial asociado al espejo de agua, en el que se llevaron a cabo diversas actividades domésticas durante el Holoceno medio y tardío, como la confección de artefactos líticos y el procesamiento y cocción de especies animales y vegetales. Durante las tareas de excavación se observó la presencia de sedimentos bioturbados que podrían ser consecuencia de la acción de diversos agentes biológicos (e.g., raíces, animales de hábitos subterráneos/fosoriales). En relación con esto, una de las particularidades del contexto excavado fue el hallazgo de una gran cantidad de estructuras de cavado producidas por mamíferos de hábitos fosoriales o semi-fosoriales (e.g., roedores y armadillos). Dado que la actividad de animales cavadores produce una importante perturbación en la estructura sedimentaria, es posible que su presencia haya generado la alteración en la distribución de los materiales arqueológicos. En este trabajo se evalúa la influencia de estos agentes en el grado de integridad y resolución del registro. Los estudios realizados permitieron comenzar a comprender la historia tafonómica del conjunto recuperado en el sitio. Los resultados obtenidos evidenciaron que el contexto arqueológico fue altamente perturbado por la acción de animales cavadores como los roedores y armadillos. En consecuencia, el sitio posee una baja resolución y una mala integridad lo que impide discriminar y caracterizar las ocupaciones correspondientes al Holoceno medio y tardío.
Shandong province, located in the Lower Yellow River, is one of the birthplaces of ancient Chinese civilization. However, the comprehensive genetic histories of this region have remained largely unknown until now due to a lack of ancient human genomes. Here, we present 21 ancient genomes from Shandong dating from the Warring States period to the Jin-Yuan Dynasties. Unlike the early Neolithic samples from Shandong, the historical samples are most closely related to post-Late Neolithic populations of the Middle Yellow River Basin, suggesting a population turnover in Shandong from the Neolithic Age to the Historical era. In addition, we detect a close genetic affinity between the historical samples in Shandong and present-day Han Chinese, showing long-term genetic stability in Han Chinese at least since the Warring States period.
RÉSUMÉ : L'organisation sociale des groupes de chasseurs-cueilleurs de la Puna de l’Atacama est encore peu étudiée. Cela n'est pas dû à un manque de recherches, mais plutôt au poids discutable d'approches environnementales et paléoclimatiques qui ont conduit à une vision réductionniste des sociétés nomades. Tout au long des 10 000 ans de la période archaïque (12 800 à 3 500 cal BP), du peuplement des populations à l'émergence des sociétés agro-pastorales, les sociétés de chasseurs-cueilleurs ont souvent été perçues comme des acteurs passifs, subissant les contraintes de l'environnement et les variations climatiques. Dans ce travail, nous explorons les réseaux d'interaction des groupes archaïques du bassin du Salar de l’Atacama (21-22°S/68°W, 2200 mètres d'altitude), au nord du Chili (Amérique du Sud). Nous nous concentrons sur le contexte et l'organisation de la production et de la circulation des matières premières lithiques dans le paysage. Des études pétrographiques et géochimiques sont combinées avec la lecture techno-économique des industries lithiques.
La recherche est structurée en quatre parties fondamentales. La Partie 1 "Le contexte de l'étude" présente le cadre archéologique et environnemental, suivi par la problématique de l'étude et la méthodologie. La partie 2 intitulée "Les matières premières lithiques" fournit une caractérisation des matières premières exploitées sur les sites archéologiques et les sources d'approvisionnement dans la zone d'étude. Ensuite, les résultats des analyses de composition chimique des obsidiennes sont détaillés. La Partie 3 "Les industries lithiques Archaïques" constitue l'essentiel de la thèse. Tout au long des différents chapitres, les résultats de l'étude technologique de chaque site et de ses différentes couches stratigraphiques sont présentés. Enfin, dans la Partie 4, "Des pierres statiques à l'interprétation sociale", nous faisons appel à l'ethnographie et à d'autres arguments complémentaires pour explorer les réseaux d'interaction et de mobilité des sociétés nomades de l'Atacama.
Soil erosion has significant negative effects on the eco-environment, and it also threatens the sustainability of agricultural production. However, studies on soil erosion in northern China during the historical period, and its relationship with climate change and human activities, are rare. Here we present a 2900-year pollen and geochemical record from a sediment core from Lingganhai Lake, an alpine freshwater lake on the Chinese Loess Plateau in northern China. We observed an abrupt increase in the influx of detrital elements at ~ 750 CE, accompanied by decreased tree pollen and increased cereal pollen percentages, which suggest severe soil erosion induced by intensified human activities. Coeval pollen and fungal spore records from other sites in the vicinity of Lingganhai Lake also indicate reduced forest cover, intensified agricultural and grazing activity, and increased
dust storm frequency. During 1250–1380 CE, decreased soil erosion at Lingganhai Lake was accompanied by forest recovery and a reduction in the intensity of human activities. However, after ~ 1380 CE, intensive soil erosion was renewed, likely caused by enhanced human activity, which partially overlapped with intensified dust
activity in northern China during the Little Ice Age. Overall, our results demonstrate the close link between vegetation cover and soil erosion, and they highlight the importance of the maintenance of montane forest in northern China for soil preservation.
Environmental development and water level changes in the south-western part of the Curonian Lagoon are reconstructed based on the results of bottom sediment investigations, including data on lithology, diatoms, pollen, and radiocarbon dating. Three stages have been identified in the ~ 10000-year history of the lagoon’s development. The diatoms suggest that in the Early Holocene, the southern part of the Curonian Lagoon was a shallow freshwater basin, mainly fed by run-off from the continent. During the Middle Holocene, the study area was a marshy coastal zone. Due to a change in hydrological conditions at the beginning of the Late Holocene, it became an open-water part of the lagoon.
The regional impact of abrupt glacial climate variability remains poorly constrained for arid southwestern Asia, particularly winter dynamics during Marine Isotope Stage 3, due to limited paleoarchives in the Middle East. Here, we present continuous speleothem records of δ¹⁸O and δ¹³C with robust chronologies for southwestern and central Iran, spanning ∼50–30 ka. Stable‐isotope signals in the two stalagmites are generally uncorrelated and do not exhibit a consistent response to Greenland stadials or interstadials; however, both show a positive δ¹⁸O excursion that coincides with Heinrich event 4. We explore the potential mechanisms for intermittent coupling of speleothem δ¹⁸O across Iran through isotope‐enabled atmospheric modeling outputs, from which we utilize the spatial δ¹⁸O gradient as a proxy for wintertime westerly versus southerly jet strength. Our results suggest that during Heinrich event 4 and several Greenland stadials, stronger westerly winds enhanced Mediterranean moisture contributions to both sites and reduced aridity in southern Iran.
The ancient city of Chichén Itzá in Yucatán, Mexico, was one of the largest and most influential Maya settlements during the Late and Terminal Classic periods (ad 600–1000) and it remains one of the most intensively studied archaeological sites in Mesoamerica1–4. However, many questions about the social and cultural use of its ceremonial spaces, as well as its population’s genetic ties to other Mesoamerican groups, remain unanswered². Here we present genome-wide data obtained from 64 subadult individuals dating to around ad 500–900 that were found in a subterranean mass burial near the Sacred Cenote (sinkhole) in the ceremonial centre of Chichén Itzá. Genetic analyses showed that all analysed individuals were male and several individuals were closely related, including two pairs of monozygotic twins. Twins feature prominently in Mayan and broader Mesoamerican mythology, where they embody qualities of duality among deities and heroes⁵, but until now they had not been identified in ancient Mayan mortuary contexts. Genetic comparison to present-day people in the region shows genetic continuity with the ancient inhabitants of Chichén Itzá, except at certain genetic loci related to human immunity, including the human leukocyte antigen complex, suggesting signals of adaptation due to infectious diseases introduced to the region during the colonial period.
The article is a variant in Romanian of chapter 4.8 of the monograph of the Foeni-Cimitirul ortodox site, which was published in 2021. Starting from the Eneolithic discoveries from this site, the characteristics of the ceramics from the Banat area are analyzed, as well as their analogies in Transylvania. These were analyzed in correlation with the 14C data and it is concluded that the Foeni Cultural Group is the one that has a contribution to the genesis of the Petreşti Culture.
The historical chronologies for dynastic Egypt are based on reign lengths inferred from written and archaeological evidence.
These floating chronologies are linked to the absolute calendar by a few ancient astronomical observations, which remain a
source of debate. We used 211 radiocarbon measurements made on samples from short-lived plants, together with a Bayesian model
incorporating historical information on reign lengths, to produce a chronology for dynastic Egypt. A small offset (19 radiocarbon
years older) in radiocarbon levels in the Nile Valley is probably a growing-season effect. Our radiocarbon data indicate that
the New Kingdom started between 1570 and 1544 B.C.E., and the reign of Djoser in the Old Kingdom started between 2691 and
2625 B.C.E.; both cases are earlier than some previous historical estimates.
If radiocarbon measurements are to be used at all for chronological purposes, we have to use statistical methods for calibration. The most widely used method of calibration can be seen as a simple application of Bayesian statistics, which uses both the information from the new measurement and information from the 14 C calibration curve. In most dating applications, however, we have larger numbers of 14 C measurements and we wish to relate those to events in the past. Bayesian statistics provides a coherent framework in which such analysis can be performed and is becoming a core element in many 14 C dating projects. This article gives an overview of the main model components used in chronological analysis, their mathematical formulation, and examples of how such analyses can be performed using the latest version of the OxCal software (v4). Many such models can be put together, in a modular fashion, from simple elements, with defined constraints and groupings. In other cases, the commonly used “uniform phase” models might not be appropriate, and ramped, exponential, or normal distributions of events might be more useful. When considering analyses of these kinds, it is useful to be able run simulations on synthetic data. Methods for performing such tests are discussed here along with other methods of diagnosing possible problems with statistical models of this kind.
The wide availability of precise radiocarbon dates has allowed researchers in a number of disciplines to address chronological questions at a resolution which was not possible 10 or 20 years ago. The use of Bayesian statistics for the analysis of groups of dates is becoming a common way to integrate all of the ¹⁴ C evidence together. However, the models most often used make a number of assumptions that may not always be appropriate. In particular, there is an assumption that all of the ¹⁴ C measurements are correct in their context and that the original ¹⁴ C concentration of the sample is properly represented by the calibration curve.
In practice, in any analysis of dates some are usually rejected as obvious outliers. However, there are Bayesian statistical methods which can be used to perform this rejection in a more objective way (Christen 1994b), but these are not often used. This paper discusses the underlying statistics and application of these methods, and extensions of them, as they are implemented in OxCal v 4.1. New methods are presented for the treatment of outliers, where the problems lie principally with the context rather than the ¹⁴ C measurement. There is also a full treatment of outlier analysis for samples that are all of the same age, which takes account of the uncertainty in the calibration curve. All of these Bayesian approaches can be used either for outlier detection and rejection or in a model averaging approach where dates most likely to be outliers are downweighted.
Another important subject is the consistent treatment of correlated uncertainties between a set of measurements and the calibration curve. This has already been discussed by Jones and Nicholls (2001) in the case of marine reservoir offsets. In this paper, the use of a similar approach for other kinds of correlated offset (such as overall measurement bias or regional offsets in the calibration curve) is discussed and the implementation of these methods in OxCal v 4.0 is presented.
This paper highlights some of the main developments to the radiocarbon calibration program, OxCal. In addition to many cosmetic changes, the latest version of OxCal uses some different algorithms for the treatment of multiple phases. The theoretical framework behind these is discussed and some model calculations demonstrated. Significant changes have also been made to the sampling algorithms used which improve the convergence of the Bayesian analysis. The convergence itself is also reported in a more comprehensive way so that problems can be traced to specific parts of the model. The use of convergence data, and other techniques for testing the implications of particular models, are described.
Statistical analysis is becoming much more widely used in conjunction with radiocarbon dating. In this paper I discuss the impact of Bayesian analysis (using computer programs such as OxCal) on archaeological research. In addition to simple analysis, the method has implications for the planning of dating projects and the assessment of the reliability of dates in their context.
A new formalism for describing chronological models is introduced here: the Chronological Query Language (CQL), an extension of the model definitions found in the program OxCal.
New methods of Bayesian analysis can be used to overcome some of the inherent biases in the uncertainty estimates of scientific dating methods. Most of these methods, including ¹⁴ C, uranium series and thermoluminescence (TL), tend to favor some calendar dates over others. ¹⁴ C calibration overcomes the problem where this is possible, but a Bayesian approach can be used more generally.
People usually study the chronologies of archaeological sites and geological sequences using many different kinds of evidence, taking into account calibrated radiocarbon dates, other dating methods and stratigraphic information. Many individual case studies demonstrate the value of using statistical methods to combine these different types of information. I have developed a computer program, OxCal, running under Windows 3.1 (for IBM PCs), that will perform both 14 C calibration and calculate what extra information can be gained from stratigraphic evidence. The program can perform automatic wiggle matches and calculate probability distributions for samples in sequences and phases. The program is written in C++ and uses Bayesian statistics and Gibbs sampling for the calculations. The program is very easy to use, both for simple calibration and complex site analysis, and will produce graphical output from virtually any printer.
Tephra from the Cape Riva (Y-2) eruption of Santorini has been found across the eastern Mediterranean. It presents an important link between marine and terrestrial records. A Poisson process (P Sequence) age-depth prior, with model averaging, is used to model individual previously published radiocarbon sequences, cross-linked with an exponential phase model parameter to obtain a robust age. Multiple sequences and C-14 determinations from 3 eastern Mediterranean data sets (Seymour et al. 2004; Margari et al. 2009; Muller et al. 2011; Roeser et al. 2012) are used in the model. The modeled age of the Y-2 tephra produced within this study is 22,329-21,088 cal BP at 95.4% probability.
Bayesian methods have been widely used to address the Iron Age chronological debate in Israel, which has implications for the entire eastern Mediterranean Iron Age chronology. However, a consensus has not been reached. This is largely because radiocarbon dates of materials in this period lie on an oscillation in the calibration curve. This study focuses on the modeling of 14C dates from the Iron I and Iron II periods, discusses the underlying assumptions and limitations of existing Bayesian chronologies, and proposes the use of a more appropriate model that allows for the phase transitions not being instantaneous. The new trapezoidal model sheds light on the probable duration of the transitions between the Iron Age phases.
DOI: 10.2458/azu_js_rc.55.16213
Single and multiphase models have been used extensively in construction of chronologies. We model more gradual transition between phases with a trapezoid model since it better reflects the nature of the information that goes into the model prior. We find that a simple trapezoid model has a bias that does not reflect prior knowledge, and thus propose an addition of a noninformative element to the prior. We also present an alternative parameterization, which transforms the current abrupt transition model into a model that allows for gradual changes. The addition of a noninformative prior ensures model flexibility. We evaluate these Bayesian models using 2 case studies. © 2012 by the Arizona Board of Regents on behalf of the University of Arizona.
Statistical analysis is becoming much more widely used in conjunction with radiocarbon dating. In this paper I discuss the impact of Bayesian analysis (using computer programs such as OxCal) on archaeological research. In addition to simple analysis, the method has implications for the planning of dating projects and the assessment of the reliability of dates in their context. A new formalism for describing chronological models is introduced here: the Chronological Query Language (CQL), an extension of the model definitions found in the program OxCal. New methods of Bayesian analysis can be used to overcome some of the inherent biases in the uncertainty estimates of scientific dating methods. Most of these methods, including 14C, uranium series and thermoluminescence (TL), tend to favor some calendar dates over others. 14C calibration overcomes the problem where this is possible, but a Bayesian approach can be used more generally.
Dating Carbon
Radiocarbon dating is the best way to determine the age of samples that contain carbon and that are younger than ∼50,000 years, the limit of precision for the method. There are several factors that complicate such age determinations, however, some of the most important of which include variability of the ¹⁴ C production in the atmosphere (which affects organic samples whose radiocarbon inventories are derived from atmospheric CO 2 ), surface ocean reservoir effects (which affect marine samples that acquire their radiocarbon signatures from seawater), and variable dead carbon fraction effects (which affect speleothems that derive their carbon from groundwaters). Bronk Ramsey et al. (p. 370 ; see the Perspective by Reimer ) avoid the need to make such assumptions, reporting the ¹⁴ C results of sediments from Lake Suigetsu, Japan. Analysis of terrestrial plant macrofossils in annually layered datable sediments yielded a direct record of atmospheric radiocarbon for the entire measurable interval up to 52.8 thousand years ago.
With the advent of the high precision radiocarbon calibration curve there is an increasing demand from archaeologists for results, previously reported on the radiocarbon scale, to be expressed on the calendar scale. Furthermore, there is a general realization within the archaeological community that much more information can be derived from radiocarbon dating if the samples are taken from coherent, well-chosen contexts and if any available substantive archaeological information is included in the data analysis. This paper describes how the Bayesian approach to statistical data analysis can be used for the calibration of groups of radiocarbon results in situations where archaeological information is available a priori about the relationships between the contexts being dated. Recent innovations in the implementation of the Bayesian paradigm are used and the methodology is illustrated by the analysis of data arising from two archaeological excavations.
Long-term sedimentary sequences provide a wealth of useful information for research into the palaeo-environment, especially in relation to past climate change. Shorter records provide similar information in many archaeological contexts. However if such records are to be used to provide precise timing of events, and more critically the relative timing between different records, methods are needed to provide accurate and precise age–depth models for these sequences. Given the imprecision of individual calibrated radiocarbon determinations it is necessary to use the information we have about the deposition process to refine our chronologies and also to provide interpolation between dated levels in any sequence. Even with layer counted chronologies, the uncertainties are sometimes hard to quantify.This paper outlines a range of Bayesian models for deposition which have been implemented in the computer programme OxCal. These models can be used to combine information from the sediments themselves with radiocarbon or other direct dating information. Such models have the potential to integrate information between different records and provide a coherent chronology on which to base environmental or archaeological research.
This paper presents a new series of AMS dates on ultrafiltered bone gelatin extracted from identified cutmarked or humanly-modified bones and teeth from the site of Abri Pataud, in the French Dordogne. The sequence of 32 new determinations provides a coherent and reliable chronology from the site's early Upper Palaeolithic levels 5-14, excavated by Hallam Movius. The results show that there were some problems with the previous series of dates, with many underestimating the real age. The new results, when calibrated and modelled using a Bayesian statistical method, allow detailed understanding of the pace of cultural changes within the Aurignacian I and II levels of the site, something not achievable before. In the future, the sequence of dates will allow wider comparison to similarly dated contexts elsewhere in Europe. High precision dating is only possible by using large suites of AMS dates from humanly-modified material within well understood archaeological sequences modelled using a Bayesian statistical method.
Flexible Bayesian methods for archaeological dating
- A J Karlsberg
Bayesian methods for the construction of robust chronologies
- S Lee