The myths and realities of Bayesian chronological modeling revealed

We review the history of Bayesian chronological modeling in archaeology and demonstrate that there has been a surge over the past several years in American archaeological applications. Most of these applications have been performed by archaeologists who are self-taught in this method because formal training opportunities in Bayesian chronological modeling are infrequently provided. We define and address misconceptions about Bayesian chronological modeling that we have encountered in conversations with colleagues and in anonymous reviews, some of which have been expressed in the published literature. Objectivity and scientific rigor is inherent in the Bayesian chronological modeling process. Each stage of this process is described in detail, and we present examples of this process in practice. Our concluding discussion focuses on the potential that Bayesian chronological modeling has for enhancing understandings of important topics

Stable isotopes, chronology and Bayesian models for the Viking archaeology of north-east Iceland

This paper reviews the results of a long-term research project that used stable isotope analyses (δ13C, δ15N, δ34S) and Bayesian mixing models to better model the chronology for a presumed Viking Age cemetery at Hofstaðir, near Lake Mývatn in north-east Iceland. δ13C and radiocarbon dating indicated that many of the individuals consumed a large amount of marine protein, which results in a marine reservoir effect (MRE), making ages older than expected. In addition to the MRE, geological activity in the region has the potential to introduce massive quantities of radioactive ‘dead’ carbon into the freshwater system, resulting in a very large freshwater reservoir effect (FRE) that can offset radiocarbon ages on the order of a few thousand years. The radiocarbon dates of organisms that derive an unknown proportion of their carbon from both marine and freshwater reservoirs are extremely difficult to ‘correct’, or, more appropriately, model. The research not only highlights the complexities of dealing with multiple reservoirs, but also how important it is to develop models that are temporally and geographically relevant to the site under study. Finally, it shows how this data can be used to inform the development of chronological models for refining the dating for archaeological activity

Research in progress: Assessing marine radiocarbon reservoir effect variation in greater Utqiaġvik, Alaska

No abstract available

Matrilines in Neolithic cattle from Orkney, Scotland reveals complex husbandry patterns of ancestry

mtDNA, isotopic and archaeozoological analyses of cattle teeth and bones from the Late Neolithic site of Links of Noltland, Orkney, Scotland revealed these animals followed similar grazing regimes but displayed diverse genetic origins and included one cattle skull that carried an aurochs (wild cattle) genetic haplotype. Morphometric analyses indicate the presence of some cattle larger than published dimensions of Neolithic domestic cattle. Several explanations for these finding are possible but may be the evidence of a complex pattern of domestic cattle introductions into Neolithic Orkney and interbreeding between domestic and wild cattle

Sequential measurement of δ15N, δ13C and δ34S values in archaeological bone collagen at the Scottish Universities Environmental Research Centre (SUERC): a new analytical frontier

Rationale: The use of multi‐isotopic analysis (δ15N, δ13C and δ34S values) of archaeological bone collagen to assist in the interpretation of diet, movement and mobility of prehistoric populations is gradually increasing, yet many researchers have traditionally avoided investigating sulphur due to its very low concentrations (<0.3%) in mammalian collagen. For this reason, and as a consequence of analytical detection limits, sulphur is usually measured separately from carbon and nitrogen, which leads to longer analytical times and higher costs. Methods: A Thermo ScientificTM EA IsoLinkTM IRMS system, with the ability to rapidly heat a gas‐chromatography (GC) column and concentrate the sample gas online without cryo‐trapping, was used at the Radiocarbon Laboratory at SUERC. Optimisation of the GC temperature and carrier gas flow rate in the elemental analyser resulted in improved signal‐to‐noise ratio and sensitivity for SO2. This allowed for routine sequential N2, CO2 and SO2 measurements on small samples of bone collagen. Results: Improvements in sample gas transfer to the mass spectrometer allows for sequential δ15N, δ13C and δ34S values to be measured in 1–1.5 mg samples of bone collagen. Moreover, the sensitivity and signal‐to‐noise ratio of the sample gas, especially SO2, is improved, resulting in precisions of ±0.15‰ for δ15N values, ±0.1‰ for δ13C values and ±0.3‰ for δ34S values. Previous instrumentation allowed for the analysis of ~30 unknown samples before undertaking maintenance; however, ~150 unknown samples can now be measured, meaning a 5‐fold increase in sample throughput. Conclusions: The ability to sequentially measure δ15N, δ13C and δ34S values rapidly in archaeological bone collagen is an attractive option to researchers who want to build larger, more succinct datasets for their sites of interest, at a much‐reduced analytical cost and without destroying larger quantities of archaeological material

Effects of Ethanol Exposure and Withdrawal on Neuronal Morphology in the Agranular Insular and Prelimbic Cortices: Relationship with Withdrawal-Related Structural Plasticity in the Nucleus Accumbens

peer-reviewedThe present study investigated the effects of chronic intermittent ethanol exposure and withdrawal on dendritic morphology and spine density in the agranular insular and prelimbic cortices. Adult male Sprague–Dawley rats were passively exposed to vaporized ethanol (~37 mg/L; 12 h/day) or air (control) for ten consecutive days. Dendritic length, branching, and spine density were quantified in layer II/III pyramidal neurons 24 hours or seven days following the final ethanol exposure. Compared to unexposed control animals there were structural alterations on neurons in the prelimbic cortex, and to a lesser extent the agranular insular cortex. The most prominent ethanol-related differences were the transient increases in dendritic length and branching in prelimbic neurons at 24 h post-cessation, and increased mushroom-shaped spines at seven days post-cessation. The results obtained in the prelimbic cortex are the opposite of those previously reported in the nucleus accumbens core (Peterson, et al. 2015), suggesting that these regions undergo distinct functional adaptations following ethanol exposure and withdrawal

Deciphering diet and monitoring movement: multiple stable isotope analysis of the Viking Age settlement at Hofstaðir, Lake Mývatn, Iceland

Objectives: A previous multi-isotope study of archaeological faunal samples from Skútustaðir, an early Viking age settlement on the southern shores of Lake Mývatn in north-east Iceland, demonstrated that there are clear differences in δ34S stable isotope values between animals deriving their dietary protein from terrestrial, freshwater, and marine reservoirs. The aim of this study was to use this information to more accurately determine the diet of humans excavated from a nearby late Viking age churchyard. Materials and Methods: δ13C, δ15N, and δ34S analyses were undertaken on terrestrial animal (n = 39) and human (n = 46) bone collagen from Hofstaðir, a high-status Viking-period farmstead ∼10 km north-west of Skútustaðir. Results: δ34S values for Hofstaðir herbivores were ∼6‰ higher relative to those from Skútustaðir (δ34S: 11.4 ± 2.3‰ versus 5.6 ± 2.8‰), while human δ13C, δ15N, and δ34S values were broad ranging (−20.2‰ to −17.3‰, 7.4‰ to 12.3‰, and 5.5‰ to 14.9‰, respectively). Discussion: Results suggest that the baseline δ34S value for the Mývatn region is higher than previously predicted due to a possible sea-spray effect, but the massive deposition of Tanytarsus gracilentus (midges) (δ34S: −3.9‰) in the soil in the immediate vicinity of the lake is potentially lowering this value. Several terrestrial herbivores displayed higher bone collagen δ34S values than their contemporaries, suggesting trade and/or movement of animals to the region from coastal areas. Broad ranging δ13C, δ15N, and δ34S values for humans suggest the population were consuming varied diets, while outliers within the dataset could conceivably have been migrants to the area

Late Holocene volcanic activity and environmental change in Highland Guatemala

We present a record of late Holocene volcanic eruptions with elemental data for a sequence of sampled tephras from Lake Amatitlan in Highland Guatemala. Our tephrochronology is anchored by a Bayesian P_Sequence age-depth model based on multiple AMS radiocarbon dates. We compare our record against a previously published study from the same area to understand the record of volcanism and environmental changes. This work has implications for understanding the effects of climate and other environmental changes that may be related to the emission of volcanic aerosols at local, regional and global scales

Three Generations Under One Roof? Bayesian Modeling of Radiocarbon Data from Nunalleq, Yukon-Kuskokwim Delta, Alaska

Acknowledgments. This research was funded through an Arts and Humanities Research Council grant (AH/K006029/1) awarded to Drs. Rick Knecht, Charlotta Hillerdal, and Kate Britton, and two NERC Radiocarbon Facility grants (NF/2015/1/6 and NF/2015/2/3) awarded to Drs. Rick Knecht and Paul Ledger. Véronique Forbes received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement number 703322. Excavations at Nunalleq have also benefited from the support of the local community who have made us all feel at home in Quinhagak. In particular, we wish to thank Qanirtuuq Incorporated and Warren Jones for logistical support and their consistently warm hospitality. Thanks also to Philip Ashlock who took the aerial image presented in Figure 3. We also wish to acknowledge the contribution of all of the students and researchers who have excavated at Nunalleq between 2009 and 2015. Without their hard work and dedication, in sometimes challenging conditions, this article would not have been possible. Finally, we wish to thank three anonymous reviewers and Robert Kelly for constructive criticism that has helped improved this manuscript. Permission for excavations at Nunalleq was granted by Qanirtuuq Incorporated.Peer reviewedPublisher PD

Type III collagen modulates fracture callus bone formation and early remodeling

Type III collagen (Col3) has been proposed to play a key role in tissue repair based upon its temporospatial expression during the healing process of many tissues, including bone. Given our previous finding that Col3 regulates the quality of cutaneous repair, as well as our recent data supporting its role in regulating osteoblast differentiation and trabecular bone quantity, we hypothesized that mice with diminished Col3 expression would exhibit altered long‐bone fracture healing. To determine the role of Col3 in bone repair, young adult wild‐type (Col3+/+) and haploinsufficent (Col3+/−) mice underwent bilateral tibial fractures. Healing was assessed 7, 14, 21, and 28 days following fracture utilizing microcomputed tomography (microCT), immunohistochemistry, and histomorphometry. MicroCT analysis revealed a small but significant increase in bone volume fraction in Col3+/− mice at day 21. However, histological analysis revealed that Col3+/− mice have less bone within the callus at days 21 and 28, which is consistent with the established role for Col3 in osteogenesis. Finally, a reduction in fracture callus osteoclastic activity in Col3+/− mice suggests Col3 also modulates callus remodeling. Although Col3 haploinsufficiency affected biological aspects of bone repair, it did not affect the regain of mechanical function in the young mice that were evaluated in this study. These findings provide evidence for a modulatory role for Col3 in fracture repair and support further investigations into its role in impaired bone healing. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:675–684, 2015.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111249/1/jor22838.pd