Calibrated Radiocarbon Dates Research Articles

Chronostratigraphy of the Late Glacial Żabinko site (western Poland) and investigation of the dose rate variability

The Żabinko exposure (western Poland) reveals the classic fluvio-aeolian succession known from studies in the European Sand Belt. Previous chronostratigraphic studies were mainly based on uncalibrated radiocarbon dates from organic sediments and thermoluminescence dating. The picture visible from these studies indicated a number of discrepancies between these methods. The new research in this exposure was based on optically stimulated luminescence (OSL) dating and calibrated radiocarbon dates. The results obtained indicate a general discrepancy between the results achieved by these two methods. While the radiocarbon dates provide some meaningful picture and allow correlation with previous studies, the results of OSL dating do not allow for a chronological model of sedimentary processes. The OSL dates show large inversions of the results and are clearly younger than the other dating results. Detailed analysis of OSL measurements shows radioactive disequilibrium and variability linked to differential stratification of sediments, significantly impacting the assessment of environmental dose rates. We believe that this atypical variability is presumably the result of postdepositional processes, such as changes in groundwater levels, chemical weathering and radionuclide migration.

Caveat emptor!—wiggle-matching European wood samples (AD 46–AD 286)

AbstractThis study suggests that there may be considerable difficulties in providing accurate calendar age estimates in the Roman period in Europe, between ca. AD 60 and ca. AD 230, using the radiocarbon calibration datasets that are currently available. Incorporating the potential for systematic offsets between the measured data and the calibration curve using the ΔR approach suggested by Hogg et al. (2019), only marginally mitigates the biases in calendar date estimates observed. At present, it clearly behoves researchers in this period to “caveat emptor” and validate the accuracy of their calibrated radiocarbon dates and chronological models against other sources of dating information.

First record of insects from the oldest and older Dryas of Altai (Russia). Coleoptera assemblages from Lebed River

Subfossil remains of insects found in the Lebed site (52.25220°N, 87.15692°E) located on the Lebed River, Altai Republic are recorded. The calibrated radiocarbon dates for two layers of these deposits were 16,461–17,056 cal BP, and 13,520–14,077 cal BP, which correspond to the oldest and older Dryas (Late Pleistocene). Insect assemblages of these deposits are mainly represented by Coleoptera, which are noteworthy there for high taxonomic and ecological diversity and include several endemic and relic species. At least 120 beetle species from 17 families have been found altogether, of them, 37 species are recorded for the Pleistocene deposits of Western Siberia for the first time. Three families, Carabidae, Staphylinidae and Curculionidae are most abundantly represented in the examined Lebed site. Ecologically, this beetle assemblage is dominated by species that are currently confined to the taiga belt and alpine meadows of the Altai Mountains; aquatic and near-water species are also well represented. The studied assemblages are rather different from the previously studied Pleistocene insect fauna in the south of the West Siberian Plain. The taxonomic and ecological compositions of the beetle fauna of Lebed site suggest its existence under humid palaeoclimate that was significantly colder than modern climate in this area.

Holocene paleoearthquakes activity in the Nieru graben, southern Tibet

The Yadong-Gulu Rift (YGR) is the longest and most prominent rift in southern Tibet. While 14 large historical earthquakes have occurred on the northern-central segment of the YGR, historical or paleoearthquake records along the southern segment remain poorly understood. The spatial discrepancy of large earthquakes has significant implications for assessing seismic hazards along the entire YGR. To address this knowledge gap, this study presents the paleoseismic events for the first time in the Nieru graben located along the southern segment of the YGR. The excavation of a paleoseismic trench reveals two Holocene earthquakes with calibrated radiocarbon dates constraining the timing of the two events to be after 4084-3954 cal yr BP. The paleoearthquake had a magnitude of M 7. The study shows that the southern segment of the YGR experienced strong paleoseismic events, except for the Relong graben. Considering the high present extension rate of the southern rifts and the magnitude of the paleoseismic events along the Nieru graben, the southern segment of the YGR holds the potential for producing large earthquakes. Furthermore, the ongoing tectonic deformation in the area, coupled with stress changes from large earthquakes on Himalayan thrust faults, may increase the likelihood of future rupture along the active faults in the Nieru graben.

Late Roman–Early Byzantine Leukos settlement, Karpathos, Greece: Geoarchaeology, archeoseismology, and paleogeography

AbstractThis archeoseismologic study focuses on the Leukos settlement that thrived on the west coast of the forearc island of Karpathos in the 4th−6th centuries CE. The onshore site occupies the eastern rim of the offshore Karpathos Basin, the deepest Aegean basin, in a sector of the Hellenic forearc typically regarded as seismically insignificant. Investigations of faulting, sedimentary processes, and secondary earthquake effects (hydraulic fracturing, liquefaction, tilting, landslides) are integrated with observations of previously surveyed and newly discovered archeological remains to appraise syn‐ to post‐Early Byzantine seismicity and establish a sequence of faulting. Calibrated radiocarbon dates, the first from Karpathos, indicate intermittent faulting and seismicity spanning the 4th−10th centuries CE, likely contributing to the early 7th‐century CE abandonment of Leukos. The coseismic rupture of competent cobbles whose fractures are filled with fluidized sediment is an established paleoseismologic tool for recognizing earthquakes of magnitude Mw ≥ 6; this study extends that criterion to archeoseismology. This study underscores the need to evaluate land movements, sea‐level fluctuations, and shoreline migration for coastal archeological sites. A plausible Late Roman paleogeography emerges in which Leukos occupied a contiguous peninsula rather than surrounding three modern harbors. This study encourages re‐evaluation of seismic and tsunami hazards in the sector of the Hellenic forearc surrounding ancient Leukos and the Karpathos Basin.

Ancient Ponds, Marl Deposits, and Native American Archaeology in the Ridge and Valley Province of Maryland and Pennsylvania

Ponds of early to middle Holocene age are identified in the Ridge and Valley Province of Maryland and Pennsylvania through the occurrence of marl deposits associated with the floodplains of low order streams. A 2-sigma calibrated radiocarbon date indicates that marl formation began no later than 7812–7326 BC. The ponds and associated wetlands are one focus of native settlement movements in the region. Excavations and borings into marl, marl-related sediments and adjacent deposits reveal sequences of marl, produced during periods of ponded and still water, alternating with strata of organic, alluvial silts. These profiles represent the shrinking, swelling, and periodic disappearance of ponds. Changes in stream dynamics and climate are explored as explanations for these physical changes. Archaeological data is useful for understanding the timing of these paleo environmental changes. In turn, an understanding of the nature of the pond environments enhances reconstructions of Indian settlement and subsistence strategies.

Shed female caribou antlers extend records of calving activity on the Arctic National Wildlife Refuge by millennia

Caribou (Rangifer tarandus) have among the longest annual migrations of any terrestrial mammal as they move from winter ranges to spring calving grounds. Biomonitoring records indicate broad consistencies in calving geography across the last several decades, but how long have herds used particular calving grounds? Furthermore, how representative are modern patterns of calving geography to periods that pre-date recent climatic perturbations and increased anthropogenic stresses? While modern ecological datasets are not long enough to address these questions, bones from past generations of caribou lying on the tundra provide unique opportunities to study historical calving geography. This is possible because female caribou shed their antlers within days of giving birth, releasing a skeletal indicator of calving. Today, the Coastal Plain of the Arctic National Wildlife Refuge (Alaska) is a key calving ground for the Porcupine Caribou Herd (PCH). To test the duration across which caribou have used this area as a calving ground, we radiocarbon dated three highly weathered female antlers collected from tundra surfaces on the Coastal Plain. Calibrated radiocarbon dates indicate that these antlers were shed between ~1,600 and more than 3,000 calendar years ago. The antiquity of these shed antlers provides the first physical evidence of calving activity on the PCH calving grounds from previous millennia, substantiating the long ecological legacy of the Coastal Plain as a caribou calving ground. Comparisons to published lake core records also reveal that dates of two of the antlers correspond to periods with average summer temperatures that were warmer than has been typical during the last several decades of biomonitoring. This finding expands the range of climatic settings in which caribou are known to use the current PCH calving grounds and suggests that the Coastal Plain of the Arctic Refuge may remain an important caribou calving ground during at least portions of predicted future warming. Discarded skeletal materials provide opportunities to assess the historical states of living populations, including aspects of reproductive biology and migration. Particularly in high-latitude settings, these insights can extend across millennia and offer rare glimpses into the past that can inform current and future management policies.

New Data on the Distribution of Southern Forests for the West Siberian Plain during the Late Pleistocene: A Paleoentomological Approach

Subfossil remains of insects and branchiopod crustaceans (Cladocera and Notostraca) found in three late Pleistocene deposits in the Novosibirsk region in the vicinity of the village of Suzun have been described. The calibrated radiocarbon dates for these deposits were 24,893–25,966 cal BP (Suzun-1), 20,379–20,699 cal BP (Suzun-2), and 27,693–28,126 cal BP (Nizhny Suzun), which correspond to the onset of marine isotope stage 2 (MIS 2). The insect assemblages of these deposits are mainly represented by Coleoptera, which are noteworthy for high taxonomic and ecological diversity. At least 194 beetle species from 21 families have been found altogether. Of them, 74 species were found in the Pleistocene deposits of Western Siberia for the first time. All deposits were similar in species composition of beetles; Carabidae and Curculionidae prevailed everywhere. The ecological composition was dominated by steppe and tundra-steppe species; aquatic and riparian groups were also well represented. The Cladoceran and notostracan taxa revealed in Suzun-1 and Suzun-2 are characteristic of recent steppes rather than the forest zone of Western Siberia. The studied entomocomplexes are congruent with the periglacial “Otiorhynchus-type” fauna that inhabited the southern part of the West Siberian Plain at the end of the Pleistocene and had no close contemporary analogues. Cold and dry conditions, as well as the prevailing open landscapes of the tundra-steppe type, were the reconstructed conditions for this fauna. At the same time, the Suzun-1 and Suzun-2 entomocomplexes had a distinctive feature, namely a high proportion of forest species associated with both coniferous and deciduous trees. According to these data, at the beginning of MIS 2 in the Upper Ob region, spruce forests with the participation of small-leaved species (birch) were present. They were probably confined to river valleys and were not widely distributed.

Paleogeography of Human Settlement at Iqaluktuuq, Victoria Island, Nunavut

Change in sea levels, be they isostatic or eustatic, impact humans and the paleogeography they inhabit. In this paper we examine paleogeography at Iqaluktuuq, a section of the Ekalluk River, Victoria Island, Nunavut, between Tahiryuaq (Ferguson Lake) and Wellington Bay. The area’s isostatic rebound impacted the Ekalluk River’s development and the use of the area by two essential subsistence resources, Arctic char (Salvelinus alpinus) and caribou (Rangifer tarandus). This, in turn, impacted the choices of Pre-Dorset, Middle and Late Dorset, and Thule/Inuit people regarding site locations. A new relative sea-level curve developed using calibrated radiocarbon dates on marine shells and terrestrial material from archaeological sites is produced for Iqaluktuuq. Based on the data, large scale (1:50,000) paleogeography maps are presented for the period of human occupation of Iqaluktuuq, 3100 calibrated years Before Present (B.P. cal) to present, revealing how paleogeography impacts people’s settlement choices.

Bayesiansk kronologisk modellering som redskab i den lovpligtige arkæologi

Bayesiansk kronologisk modellering som redskab i den lovpligtige arkæologi

Copper smelting and refining in the Pampa de Chaparrí, Lambayeque, Peru, ca. 1030–1180 cal AD.

This article reconstructs the smelting and refining of copper at site 256A01 in the Pampa de Chaparrí, near Batán Grande, Department of Lambayeque, Peru. Two banks of furnaces were excavated, yielding calibrated radiocarbon dates between 1030 and 1180 AD (Middle Sicán through the Early Late Sicán period). This is the first published study from South America to have recorded evidence of copper smelting slags that were fully liquid in furnaces apparently powered by blowpipes. The copper prills produced at 256A01 contained up to 5.5% arsenic, but we have found no evidence for deliberate addition of an arsenic-bearing mineral to the furnace charge. Some of the primary copper was heavily contaminated with metallic iron, which was removed by selective reoxidation on shallow ceramic crucibles. Although there were residual sulfides in the ore, no evidence of co-smelting (reaction of copper oxides with copper sulfides) was noted.

From Neolithic Boom-and-Bust to Iron Age Peak and Decline: Population and Settlement Dynamics in Southern Sweden Inferred from Summed Radiocarbon Dates

This article presents 6637 radiocarbon dates from archaeological sites in southernmost Sweden, from 9000 cal bc to the present. Based on summed probability distributions (SPDs) of the calibrated radiocarbon dates, the authors consider long-term trends in settlement and human population. Most dates are from the fertile and densely populated plains of south-western Scania, but coastal lowlands and forested uplands are also represented, allowing for a discussion of the relationship between central and peripheral areas. The authors distinguish between different types of archaeological contexts and features and between different types of dated material, so as to better understand the processes behind population and settlement change. They highlight three periods and phenomena revealed by the SPDs: a strong population increase at the onset of the Neolithic (4000–3700 cal bc), followed by a sharp decline; a steady and long-lasting expansion from the Early Bronze Age to the Roman Iron Age (1500 cal bc–cal ad 200); and a decrease in the Nordic Late Iron Age (seventh century ad), particularly in recently colonized upland areas. The SPDs presented provide a new framework for archaeology in southern Sweden and offer an empirical basis for discussion of long-term trends in settlement and population development.

Neolithic Burials in the Zelinda River Mouth, Northern Angara: Burial Practices and Radiocarbon Chronology

We describe new findings relating to Neolithic burials at two cemeteries in the Northern Angara area, excavated in 2012 by the Boguchany archaeological expedition. The sites are located at the outlet of the Zelinda—the right tributary of the Angara. Two burials were revealed at Ust-Zelinda-1, and five at Ust-Zelinda-2. We describe preserved remains and the funerary rite, and analyze radiocarbon dates generated from the human bones. On the basis of archaeological parallels, we attribute certain burials to the Isakovo culture. Burial practices include the use of “ocher” and the supine position of the buried along the Angara, heads to the south, upstream of the site. Calibrated radiocarbon dates, details of the funerary rite, grave goods and their typological characteristics, as well as the placement of graves within the cemeteries, suggest that three chronological groups existed within the 7499–5583 cal BP (5550–3634 cal BC) interval. The 14C date of the third group (5718–5583 cal BP, or 3769–3634 cal BC), details of the funerary rite, and grave goods are indicative of the Late Neolithic (Isakovo culture of the Southern Angara). Burials of the second group, which is the best represented (7157–6555 cal BP, or 5208–4606 cal BC), resemble those of the classic Isakovo tradition. The burial (without grave goods) attributed to the fi rst chronological group dates to 7499–7317 cal BP, or 5550– 5368 cal BC. It is hypothesized that “proto-Isakovo” traditions originated on the Northern Angara, having later spread to the Southern Angara.

Pedigree-based Bayesian modelling of radiocarbon dates.

Within the last decade, archaeogenetic analysis has revolutionized archaeological research and enabled novel insights into mobility, relatedness and health of past societies. Now, it is possible to develop these results further and integrate archaeogenetic insights into biological relatedness with radiocarbon dates as means of chronologically sequenced information. In our article, we demonstrate the potential of combining relative chronological information with absolute radiocarbon dates by Bayesian interpretation in order to improve age determinations. Using artificial pedigrees with four sets of simulated radiocarbon dates we show that the combination of relationship information with radiocarbon dates improves the age determination in many cases at least between 20 to 50%. Calibrated age ranges are more constrained than simply calibrating radiocarbon ages independently from each other. Thereby, the precision of modelled ages depends on the precision of the single radiocarbon dates, the number of modelled generations, the shape of the calibration curve and the availability of samples that can be precisely fixed in time due to specific patterns in the calibration curve (“anchor points”). Ambiguous calibrated radiocarbon dates, which are caused by inversions of the calibration curve, can be partly or almost entirely resolved through Bayesian modelling based upon information from pedigrees. Finally, we discuss selected case studies of biological pedigrees achieved for Early Bronze Age Southern Germany by recent archaeogenetic analysis, whereby the sites and pedigrees differ with regard to the quality of information, which can be used for a Bayesian model of the radiocarbon dates. In accordance with the abstract models, radiocarbon dates can again be better constrained and are therefore more applicable for archaeological interpretation and chronological placement of the dated individuals.

A complex study of anthropological materials of the Maitan burial ground of the Bronze Age Alakul Culture in Central Kazakhstan

A correlation of the results of the study of the paleoanthropological materials from the necropolis of Maitan by different scientific methods has been carried out in order to establish chronological and spatial differentiation of the burial ground and origins of the group. The complex approach allows the analysis of the problems of absolute and relative chronologies of the necropolis, demographic dynamics of the group in the context of the natural envi-ronment, and anthropological and genetic structure of the Bronze Age populations of the Eurasian steppes. The paleodemographic context reconstructed for the Maitan group is typical for the populations of the Bronze Age; some of its features may indicate an early period of adaptation, possibly related to migration of the group into the new territory. The intergroup statistical analysis of craniological materials suggests primarily western origins of the people. Particular craniological characteristics of some interred of the necropolis correspond with the recorded on the Maitan ware long-distance imports from the Urals-Tobol region of the Alakul Culture. For the first time on the materials of a numerically representative series of samples of humans and terrestrial herbivores of the Bronze Age Central Kazakhstan, Upper Tobol River region, and Trans-Urals steppes, the regional isotopic background has been established. Some individuals from the earliest burials of Maitan, according to the radiocarbon dating, are similar in isotopic ratios of carbon and nitrogen to the groups from further western regions of the Upper Tobol River steppes, whereas the other interred correspond in the isotopic values with local Central Kazakhstan sam-ples. It is possible that at the later stages of the spatial organization of the necropolis, women featuring a genetic profile different from other individuals and buried within the fences of the western planigraphic group took part in the formation of its remaining collective. In general, according to the series of calibrated radiocarbon dates, Mai-tan burial ground dates to the 18th — early 17th century BC.

Oscylacje klimatyczne w zakresie 20 000–11 000 cal BP zapisane w utworach formacji Piaski i Szerokie w odkrywkach Kopalni Węgla Brunatnego Bełchatów: spojrzenie poprzez analizę dat radiowęglowych

Radiocarbon dates of organic sediments, taken from the soil horizon, gyttja, peats, plant remains and mineral-organic sediments – silts and silty-sandy sediments with admixture of organic material – were collected and analysed. Age determinations were made for samples collected over a number of years from the upper part of sediments of the Piaski and Szerokie Formations in the Bełchatów Lignite Open Cast Mine (28 dates) and their surroundings (2 dates) (Fig. 1; Tab. 1). The organic sediments analysed are mainly associated with the valleys of the Krasówka, Struga Żłobnicka, Świętojanka and Widawka Rivers. They were formed within alluvia (probably fillings of oxbow lakes). Some of the organic deposits were formed in the vicinity of dunes or aeolian covers (mid-dune depressions). During the Late Glacial in this area, aggradation dominated the river valleys. Fluvial processes were accompanied by aeolian processes. A large proportion of aeolian grains is characteristic of the upper part of the profile of the sands formations. Despite the filling of the valleys with fluvio-aeolian sediments, fluvial erosion also occurred in places. The Folwark 1 and 2 sites in the Struga Żłobnicka River valley yielded 12 age determinations (from 14 810±170 to 11 130±120 BP, i.e. 18 270–12 900 cal BP). In the Widawka valley, the sites Bełchatów 3/88 BM, JG, I/83/JG, II/83/JG, Buczyna 8, Rogowiec 1 and Wola Grzymalina yielded 12 dates falling in the pe-riod 14 350±580 to 10 160±140 BP, i.e. 18 240––11 400 cal BP. In the Kleszczów 3/90 site, only one date of 11 460±120 BP (13 460–13 190 cal BP) related to peat in the Świętojanka River valley. The last two determinations, archived as site unknown and Kuców C–IIa, are dated 15 850±180 (19 360–18 930 cal BP) and 13 780±130 BP (16 950–16 520 cal BP). In the area of the present Szczerców field, the Parchliny-Chabielice site yielded three dates in the Krasówka River valley – 10 290±90 (12 450–11 830 cal BP), 11 840±110 BP (13 800–13 520 cal BP) and 15 440±160 (18 910–18 360 cal BP) (Tab. 1). Based on the collected dates, so-called PDF (Probability Density Functions) curves were drawn up in the range 20 000–11 000 cal BP (Fig. 3). The analysis used the shape analysis method of the summed probability density distributions of the calibrated radiocarbon dates (Fig. 3). The position of peaks of the obtained distributions on the time axis is in good agreement with the oxygen curve from the Greenland core NGRIP. There is a clear clustering of dates around the beginning of GI–1, but also around GI–1d, GI–1c2 and GI–1b. This was contributed to by the preferential sampling for dating from locations where changes in sediment lithology were evident (bottom and top of peat layer, soil on mineral deposits, bottom of oxbow fill, etc.). Therefore, the peaks of the obtained distributions should not be linked only to warm periods, but rather to transitions from cold to warm conditions or from warm to cold conditions. Although the dataset analysed is smallscale, the evident clustering of dates makes it possible to identify environmental responses to climate change over several time scales: - 19 500–18 900 cal BP (peak within GS–2b); - 17 800–17 300 cal BP (peak at transition GS––2b/GS–2a); - 16 800–16 600 cal BP (peak located at GS– –2a); - 15 200–14 300 cal BP (peak at GS–2a/GI–1e transition); - 14 100–13 800 cal BP (peak around GI–1d); - 13 600–13 550 cal BP (peak around GI–1c2); - 13 250–13 050 cal BP (peak around GI-1b); - 12 500–11 700 cal BP (peak around the second half of GS–1) The resolution of the analyses carried out does not make it possible to determine whether there were delays in the environmental response of the study area in relation to the changes recorded in the Greenlandic core, but any delays must be less than the average uncertainty of the radiocarbon dates analysed, i.e. ~100 years. The analyses carried out used dates made using conventional techniques, which have relatively large uncertainties. It is probable that including new sites and precise 14C age determinations by the AMS technique would contribute to a higher resolution of this type of analysis.

Formal Tests for Resistance-Resilience in Archaeological Time Series

The study of resilience is a common pathway for scientific data to inform policy and practice towards impending climate change. Consequently, understanding the mechanisms and features that contribute towards building resilience is a key goal of much research on coupled socio-environmental systems. In parallel, archaeology has developed the ambition to contribute to this agenda through its unique focus on cultural dynamics that occur over the very long term. This paper argues that archaeological studies of resilience are limited in scope and potential impact by incomplete operational definitions of resilience, itself a multifaceted and contested concept. This lack of interdisciplinary engagement fundamentally limits archaeology’s ability to contribute meaningfully to understanding factors behind the emergence and maintenance of long-term societal resilience, a topic of significant interest that the field is in theory ideally positioned to address. Here, we introduce resilience metrics drawn from ecology and develop case studies to illustrate their potential utility for archaeological studies. We achieve this by extending methods for formally measuring resistance, the capacity of a system to absorb disturbances; and resilience, its capacity to recover from disturbances, with a novel significance test for palaeodemographic data. Building on statistical permutation and post-hoc tests available in the rcarbon package in the R statistical environment, we apply our adapted resilience-resistance framework to summed probability distributions of calibrated radiocarbon dates drawn from the Atlantic Forest of eastern Brazil. We deploy these methods to investigate cross-sectional trends across three recognised biogeographical zones of the Atlantic Forest domain, against the backdrop of prehistoric phases of heightened hydroclimatic variability. Our analysis uncovers novel centennial-scale spatial structure in the resilience of palaeodemographic growth rates. In addition to the case-specific findings, we suggest that adapting formal metrics can help archaeology create impact and engagement beyond relatively narrow disciplinary concerns. To this end, we supply code and data to replicate our palaeodemographic analyses to enable their use and adaptation to other archaeological problems.

Investigating geoarchaeological deposits from Naihehe cave in the Sigatoka River valley of Viti Levu, Fiji

This report summarizes the results of a series of original investigations of Naihehe Cave on Viti Levu, Fiji, which include excavations and laboratory analyses. The goal of this research was to investigate evidence of human occupation of Naihehe cave in prehistory via analyses of sediments, sedimentary processes, and identification of parent materials and anthropogenic deposits. Analyses of sediments were conducted at “macro” and “micro”-scales: the macro-scale approach analyzed aggregates of sediment grains using Fourier Transform Infrared spectroscopy (FTIR) and Laser-ablated Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). The micro-scale approach focused on individual grains of sediment using Scanning Electron Microscopy with Energy Dispersion Spectroscopy (SEM-EDS). Identified charcoal and radiocarbon dating were used to determine the age of deposits. The results of these analyses identified different classes of sediment based upon their textural and mineralogical qualities and determined major and minor elemental components of individual grains and aggregates. These in turn provide unique insights into the origin and depositional environment of the cave’s sediments. Analyses also identified anthropogenic deposits via the detection of elemental and mineralogical signatures and intrusive microfossils. Combustion features in the cave’s deposits, two of which produced calibrated radiocarbon dates of 886-1013 CE (2σ) and 260-529 CE (2σ), identify human activity in the cave in the two millennia following human colonization of Fiji. This report discusses these primary findings and argues that instrument-based studies of sediment are insightful for the identification of natural and anthropogenic deposits.

End-to-end Bayesian analysis for summarizing sets of radiocarbon dates

Archaeologists and demographers increasingly employ aggregations of published radiocarbon (14C) dates as demographic proxies summarizing changes in human activity in past societies. Presently, summed probability densities (SPDs) of calibrated radiocarbon dates are the dominant method of using 14C dates to reconstruct demographic trends. Unfortunately, SPDs are incapable of converging on the distribution that generated a set of radiocarbon measurements, even when the number of observations is large. To overcome this problem, we propose a more principled alternative that combines finite mixture models and end-to-end Bayesian inference. Numerical simulations and an assessment of the statistical identifiability of our method demonstrate that it correctly converges on the generating distribution for two important models, exponentials and finite Gaussian mixtures, at least if the same statistical model is used to fit the data as was used to generate the data. To further validate this approach, we apply it to a set of radiocarbon dates from the Maya city of Tikal. We show that an end-to-end approach reconstructs with high accuracy expert demographic reconstructions based on settlement patterns and ceramics, but with more precise time-resolution and characterization of uncertainty than has heretofore been possible. Future work should consider alternatives to finite Gaussian mixtures for fitting the generating distribution.

Long-Term Demographic Trends in Prehistoric Italy: Climate Impacts and Regionalised Socio-Ecological Trajectories

The Italian peninsula offers an excellent case study within which to investigate long-term regional demographic trends and their response to climate fluctuations, especially given its diverse landscapes, latitudinal range and varied elevations. In the past two decades, summed probability distributions of calibrated radiocarbon dates have become an important method for inferring population dynamics in prehistory. Recent advances in this approach also allow for statistical assessment of spatio-temporal patterning in demographic trends. In this paper we reconstruct population change for the whole Italian peninsula from the Late Mesolithic to the Early Iron Age (10,000–2800 cal yr BP). How did population patterns vary across time and space? Were fluctuations in human population related to climate change? In order to answer these questions, we have collated a large list of published radiocarbon dates (n = 4010) and use this list firstly to infer the demographic trends for the Italian peninsula as a whole, before addressing each of five sub-regions in turn (northern, central, and southern Italy, Sicily, Sardinia). We also compare population fluctuations with local paleoclimate proxies (cave, lake, marine records). At a pan-regional scale, the results show a general rapid and substantial increase in population in the Early Neolithic with the introduction of farming at around 8000 cal yr BP and further dramatic increases during the Bronze and Iron Age (~ 3800–2800 cal yr BP). However, different regional demographic trajectories exist across different regions of Italy, suggesting a variety of localised human responses to climate shifts. Population and climate appear to have been more closely correlated during the early–mid Holocene (Mesolithic–Neolithic), while later in the Holocene (Bronze–Iron Ages) they decouple. Overall, across the Holocene the population dynamics varied by region and depended on the long-term socio-ecological dynamics prevailing in a given area. Finally, we include a brief response to the paper ‘Radiocarbon dated trends and central Mediterranean prehistory’ by Parkinson et al. (J Word Prehist 34(3), 2021)—synchronously published by Journal of World Prehistory but wholly independently developed—indicating how our conclusions accord with or differ from one another.