3 research outputs found
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Challenges in Reconstructing Past Exploitations of Atlantic Cod: A Zooarchaeological Case Study from Early Medieval England
The thesis presents a novel zooarchaeological, statistical, and ecological analysis of fish bone assemblages from early medieval England. Comprehensive evidence is presented of coastal and pelagic fishing of larger bodied, healthier populations in England from the 8th cent.CE, pushing back the assumed rise in marine fishing commonly referred to as the ‘Fish Event Horizon’, or the FEH, by 300 years. The findings are an important contribution to assessing past human impacts on aquatic ecosystems, which to date have not been widely researched.
Atlantic cod (Gadus morhua) was selected as the main focus of the study due to its prominence in modern and historical fishery economies, based on studies of modern and archaeological materials.
Identifications of diverse marine taxa, including cod, were part of the zooarchaeological analysis of a previously unexamined, exceptionally large assemblage from the pre-FEH monastic site of Lyminge. Lyminge was chosen for analysis due to its early occupation dates, which precede the previously theorised onset of marine fishing, and its exceptionally large fish bone assemblage. Fish body sizes were estimated from both newly developed and preexisting regression models. The novel models were constructed from a uniquely large and diverse dataset of modern cod specimens collected for this purpose, and applied to new data from Lyminge and to a legacy dataset from Coppergate. The estimated archaeological cod sizes were further compared to modern trawl survey data. A significant temporal decrease was observed between both archaeological datasets and the modern data. The larger archaeological cod body sizes suggest significantly improved weights, reproductivity, and health of cod populations prior to the onset of commercial fishing in the North Sea. Furthermore, shifts in past food web interactions are also suggested, revealing shifting ecologies of other species interacting in the same food web.
Combined with the positive identifications of other pelagic species, the larger archaeological sizes indicate that the fish were sourced from pelagic environments. The contextualization of these findings in the wider study area of northwest Europe suggests that early medieval communities had the technological abilities and traditional knowledge required to conduct offshore marine fishing as early as 1,300 years ago. The analysis of skeletal elements and butchery patterns of the Lyminge cod further indicate that stockfish was prepared for local consumption, and possibly for trade, in the same era.
Unique statistical tools are presented for estimating past cod sizes, expressed as Total Length (TL), through both newly defined and preexisting measurements of archaeological bones. The robustness and convenience of estimating cod TLs from previously unutilized vertebrae and cranial measurements is demonstrated through the reported accuracy of the developed regression models, and their application to the archaeological case studies where such elements are common but have remained unutilized.
Lastly, the ecological results based on the developed regression models highlight the damaging effects of intensified fishing practices in later periods, a trajectory that has led to diminished health, and even complete collapse, of modern populations
Ancient DNA sequence quality is independent of fish bone weight
The field of ancient DNA (aDNA) typically uses between 50 and 200 mg of minimum input weight of bone material for the extraction of DNA from archaeological remains. While laboratory and analysis techniques have focused on improved efficiency of extracting useable sequence data from older and poorer quality remains, bone material input requirements have rarely been critically evaluated. Here, we present the aDNA analysis of 121 size-constrained Atlantic herring remains – weighing between <10 and 70 mg – that were individually sequenced to explore the capacity of successful aDNA retrieval from small archaeological remains. We statistically evaluate the relationship between bone weight and several response variables, including library success, endogenous DNA content, and library complexity, i.e., the number of unique molecules that are obtained. Remarkably, we find no relationship between bone weight and library success, levels of endogenous DNA, or library complexity. Our results imply that – at least in the case of fish bone – even minute bones can yield positive results and that the presumed minimum sample size required should be re-evaluated. Archaeological site, instead of bone size, is the primary driver of DNA sequence quality. Our work expands the number of specimens considered suitable for aDNA analyses, and therefore facilitates efforts to minimize the destructive impact of aDNA research and mediate some of the ethical concerns surrounding destructive analysis.publishedVersio
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Ancient trash mounds unravel urban collapse a century before the end of Byzantine hegemony in the southern Levant.
The historic event of the Late Antique Little Ice Age (LALIA) was recently identified in dozens of natural and geological climate proxies of the northern hemisphere. Although this climatic downturn was proposed as a major cause for pandemic and extensive societal upheavals in the sixth-seventh centuries CE, archaeological evidence for the magnitude of societal response to this event is sparse. This study uses ancient trash mounds as a type of proxy for identifying societal crisis in the urban domain, and employs multidisciplinary investigations to establish the terminal date of organized trash collection and high-level municipal functioning on a city-wide scale. Survey, excavation, sediment analysis, and geographic information system assessment of mound volume were conducted on a series of mounds surrounding the Byzantine urban settlement of Elusa in the Negev Desert. These reveal the massive collection and dumping of domestic and construction waste over time on the city edges. Carbon dating of charred seeds and charcoal fragments combined with ceramic analysis establish the end date of orchestrated trash removal near the mid-sixth century, coinciding closely with the beginning of the LALIA event and outbreak of the Justinian Plague in the year 541. This evidence for societal decline during the sixth century ties with other arguments for urban dysfunction across the Byzantine Levant at this time. We demonstrate the utility of trash mounds as sensitive proxies of social response and unravel the time-space dynamics of urban collapse, suggesting diminished resilience to rapid climate change in the frontier Negev region of the empire