We describe a combination of methods applied to obtain reliable estimations of population density using archaeological data. The combination is based on a hierarchical model of scale levels. The necessary data and methods used to obtain the results are chosen so as to define transfer functions from one scale level to another. We apply our method to data sets from western Germany that cover early Neolithic, Iron Age, Roman, and Merovingian times as well as historical data from AD 1800. Error margins and natural and historical variability are discussed. Our results for nonstate societies are always lower than conventional estimations compiled from the literature, and we discuss the reasons for this finding. At the end, we compare the calculated local and global population densities with other estimations from different parts of the world. Keywordssettlement archaeology, population density, site density, Bandkeramik settlements, LBK culture, Aldenhovener Platte, Rhineland, Germany, Neolithic. Cover Page FootnoteWe thank Irmela Herzog (LVR-Bodendenkmalpfl ege Rheinland, Bonn) for her kernel density estimation computer program; Irmela Herzog and Thomas Frank (Universität zu Köln) for the preparation of the actual Bandkeramik data set from the lower Rhine basin; and Niels Müller-Scheessel (Römisch-GermanischeKommission, Frankfurt am Main) for the isoline circumscribing the Hallstatt necropolises of southern Germany. The remarks of the referees were very useful for improving the text. And last but not least, we are grateful to the German Research Foundation (DFG) for funding the archaeological project of the Rhine-LUCIFS framework.This open access article is available in Human Biology: http://digitalcommons.wayne.edu/humbiol/vol81/iss2/13 Estimations of Population Density for Selected Periods Between the Neolithic and AD 1800Andreas Zimmermann, 1 Johanna Hilpert, 1 and Karl Peter Wendt 1 Abstract We describe a combination of methods applied to obtain reliable estimations of population density using archaeological data. The combination is based on a hierarchical model of scale levels. The necessary data and methods used to obtain the results are chosen so as to defi ne transfer functions from one scale level to another. We apply our method to data sets from western Germany that cover early Neolithic, Iron Age, Roman, and Merovingian times as well as historical data from AD 1800. Error margins and natural and historical variability are discussed. Our results for nonstate societies are always lower than conventional estimations compiled from the literature, and we discuss the reasons for this fi nding. At the end, we compare the calculated local and global population densities with other estimations from different parts of the world.

Background Patients on hemodialysis have an elevated risk for COVID-19 infection but were not included in efficacy trials of SARS-CoV-2 vaccines. Methods We conducted a retrospective, observational study to estimate the real-world effectiveness and immunogenicity of two mRNA SARS-CoV-2 vaccines in a large, representative population of adult hemodialysis patients in the United States. In separate, parallel analyses, patients who began a vaccination series with BNT162b2 or mRNA-1273 in January and February 2021 were matched with unvaccinated patients and followed after they completed the first of two doses. In a subset of patients, blood samples were collected approximately 28 days after the second dose and anti-SARS-CoV-2 immunoglobulin G was measured. Results A total of 12,169 patients received the BNT162b2 vaccine (matched with 44,377 unvaccinated controls); 23,037 patients received the mRNA-1273 vaccine (matched with 63,243 unvaccinated controls). Compared with controls, vaccinated patients' risk of being diagnosed with COVID-19 post-vaccination became progressively lower after the first dose (day 1) to days ≥43. Following a COVID-19 diagnosis, vaccinated patients were significantly less likely than unvaccinated patients to be hospitalized (for BNT162b2, 28.0% versus 43.4%; for mRNA-1273, 37.2% versus 45.6%) and significantly less likely to die (for BNT162b2, 4.0% versus 12.1%; for mRNA-1273, 5.6% versus 14.5%). Antibodies were detected in 98.1% (309/315) and 96.0% (308/321) of BNT162b2 and mRNA-1273 patients, respectively. Conclusions In patients on hemodialysis, vaccination with BNT162b2 or mRNA-12 was associated with a lower risk of COVID-19 diagnosis and significantly lower risk of hospitalization or death among those diagnosed with COVID-19. SARS-CoV-2 antibodies were detected in nearly all patients after vaccination. These findings support the use of these vaccines in this population.

In many theories on the social and cultural evolution of human societies, the number and density of people living together in a given time and region is a crucial factor. Because direct data on past demographic developments are lacking, and reliability and validity of demographic proxies require careful evaluation, the topic has been approached from several different directions. This paper provides an introduction to a geostatistical approach for estimating prehistoric population size and density, the so-called Cologne Protocol and discusses underlying theoretical assumptions and upscaling transfer-functions between different spatial scale levels. We describe and compare the specifics for farming and for foraging societies and, using examples, discuss a diachronic series of estimates, covering the population dynamics of roughly 40 kyr of European prehistory. Ethnohistoric accounts, results from other approaches—including absolute (ethno-environmental models) and relative estimates (site-numbers, dates as data, etc.) allow a first positioning of the estimates within this field of research. Future enhancements, applications and testing of the Cologne Protocol are outlined and positioned within the general theoretical and methodological avenues of palaeodemographic research. In addition, we provide manuals for modelling Core Areas in M ap I nfo , A rc GIS, QGIS/S aga and R. This article is part of the theme issue ‘Cross-disciplinary approaches to prehistoric demography’.

Estimations of population density, which consider regional variability, are an important key variable in archaeology as they have consequences not only for the environmental but also for the economical and social domains. In this paper, a ten-step procedure of a consistent group of methods is described which deals with the data required for estimations of population density at different scale levels (from excavation to large-scale distribution maps). For distribution maps, a method is presented by which densities of sites are displayed using optimal isolines. These demarcate so called 'settlement areas' at scales of between 1:25,000 and 1:2.5 million. Our knowledge of the density of households from key areas with the most complete archaeological records is upscaled for the regions within these isolines. The results of this procedure are estimations of population density for the early Neolithic (Bandkeramik, 51st century BC) and the Roman period (2nd century AD) for regions with some 10,000 km². A simple statistical/graphical method is developed to analyse the relationship between settlement areas, soils, and precipitation. Taking into account the aspects of preservation of sites and the intensity of archaeological observations, an analysis of patterns of land use shows that in prehistory not all areas suitable for use were in fact incorporated into settlement areas. For prehistory, the idea of a most optimised use of land up to its carrying capacity (as it has been proposed for at least 50 years) can be falsified for specific areas. A large number of empty regions with good ecological conditions but lacking in settlement activity can be discussed as resulting from culture historical processes. As an example, the separation of areas inhabited by groups of different identities is discussed. The amount of used space (in terms of 'settlement area') however, increases from the early Neolithic to the 4th century BC from 5% to more than 40% . The increase between the Neolithic and the Iron Age is understood in terms of technological developments in farming systems. The percentage of areas with suitable conditions actually utilised between the Bandkeramik and Iron Age increases from 31.1% to 67.5% in the area covered by the Geschichtlicher Atlas der Rheinlande, and is much higher still in the Roman period (84.3%). State societies seem to use the land more efficiently compared to non-state systems. This is becoming even clearer on consideration of the intensity of human impact.Large-scale distribution maps dividing the Neolithic in five periods were analysed. In each of the periods large settlement areas seem to be characterised either by the development of specific cultural innovations or by exchange of a specific raw material. In the course of time, the size of settlement areas in a specific region fluctuates markedly. It is most plausible to assume that this is due to a remarkable mobility of seemingly sedentary populations. Individual families recombine to new socio-cultural units every few hundred years.The relations...

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