Culture, space, and metapopulation: a simulation-based study for evaluating signals of blending and branching

This paper explores the robustness of phylogenetic methods for detecting variations in branching and blending signals in the archaeological record. Both processes can generate a spatial structure whereby cultural similarity between different sites decays with increasing spatial distance. By generating a series of artificial records through the controlled and parameterised environment of an agent-based simulation, we: a) illustrate the weakness and the strength of different analytical techniques (empirical distogram, Mantel test, Retention Index, and d-score); b) determine whether they are capable of assessing how spatial isolation determines cultural diversity; and c) establish whether they can detect variations in the nature of horizontal transmission over time. Results suggest that variables other than the spatial range of interaction (e.g. the frequency of fission events, population dynamics, and rates of cultural innovation) have different effects on the output of some phylogenetic analyses

Is Neolithic land use correlated with demography? An evaluation of pollen-derived land cover and radiocarbon-inferred demographic change from Central Europe

The transformation of natural landscapes in Middle Europe began in the Neolithic as a result of the introduction of food-producing economies. This paper examines the relation between land-cover and demographic change in a regionally restricted case study. The study area is the Western Lake Constance area which has very detailed palynological as well as archaeological records. We compare land-cover change derived from nine pollen records using a pseudo-biomisation approach with 14C date probability density functions from archaeological sites which serve as a demographic proxy. We chose the Lake Constance area as a regional example where the pollen signal integrates a larger spatial pattern. The land-cover reconstructions for this region show first notable impacts at the Middle to Young Neolithic transition. The beginning of the Bronze Age is characterised by increases of arable land and pasture/meadow, whereas the deciduous woodland decreases dramatically. Changes in the land-cover classes show a correlation with the 14C density curve: the correlation is best with secondary woodland in the Young Neolithic which reflects the lake shore settlement dynamics. In the Early Bronze Age, the radiocarbon density correlates with open land-cover classes, such as pasture, meadow and arable land, reflecting a change in the land-use strategy. The close overall correspondence between the two archives implies that population dynamics and land-cover change were intrinsically linked. We therefore see human impact as a key driver for vegetation change in the Neolithic. Climate might have an influence on vegetation development, but the changes caused by human land use are clearly detectable from Neolithic times, at least in these densely settled, mid-altitude landscapes

British Neolithic Axehead Distributions and Their Implications

Neolithic stone axeheads from Britain provide an unusually rich, well-provenanced set of evidence with which to consider patterns of prehistoric production and exchange. It is no surprise then that these objects have often been subject to spatial analysis in terms of the relationship between particular stone source areas and the distribution of axeheads made from those stones. At stake in such analysis are important interpretative issues to do with how we view the role of material value, supply, exchange, and demand in prehistoric societies. This paper returns to some of these well-established debates in the light of accumulating British Neolithic evidence and via the greater analytical power and flexibility afforded by recent computational methods. Our analyses make a case that spatial distributions of prehistoric axeheads cannot be explained merely as the result of uneven resource availability in the landscape, but instead reflect the active favouring of particular sources over known alternatives. Above and beyond these patterns, we also demonstrate that more populated parts of Early Neolithic Britain were an increased pull factor affecting the longer-range distribution of these objects

Isolation-by-distance, homophily, and “core” vs. “package” cultural evolution models in Neolithic Europe

Recently there has been growing interest in characterising population structure in cultural data in the context of ongoing debates about the potential of cultural group selection as an evolutionary process. Here we use archaeological data for this purpose, which brings in a temporal as well as spatial dimension. We analyse two distinct material cultures (pottery and personal ornaments) from Neolithic Europe, in order to: a) determine whether archaeologically defined “cultures” exhibit marked discontinuities in space and time, supporting the existence of a population structure, or merely isolation-by-distance; and b) investigate the extent to which cultures can be conceived as structuring “cores” or as multiple and historically independent “packages”. Our results support the existence of a robust population structure comparable to previous studies on human culture, and shows how the two material cultures exhibit profound differences in their spatial and temporal structuring, signalling different evolutionary trajectories

Cycles in Stone Mining and Copper Circulation in Europe 5500–2000 BC: A View from Space

The authors of this article consider the relationship in European prehistory between the procurement of high-quality stones (for axeheads, daggers, and other tools) on the one hand, and the early mining, crafting, and deposition of copper on the other. The data consist of radiocarbon dates for the exploitation of stone quarries, flint mines, and copper mines, and of information regarding the frequency through time of jade axeheads and copper artefacts. By adopting a broad perspective, spanning much of central-western Europe from 5500 to 2000 bc, they identify a general pattern in which the circulation of the first copper artefacts was associated with a decline in specialized stone quarrying. The latter re-emerged in certain regions when copper use decreased, before declining more permanently in the Bell Beaker phase, once copper became more generally available. Regional variations reflect the degrees of connectivity among overlapping copper exchange networks. The patterns revealed are in keeping with previous understandings, refine them through quantification and demonstrate their cyclical nature, with additional reference to likely local demographic trajectories

Regional population collapse followed initial agriculture booms in mid-Holocene Europe.

Following its initial arrival in SE Europe 8,500 years ago agriculture spread throughout the continent, changing food production and consumption patterns and increasing population densities. Here we show that, in contrast to the steady population growth usually assumed, the introduction of agriculture into Europe was followed by a boom-and-bust pattern in the density of regional populations. We demonstrate that summed calibrated radiocarbon date distributions and simulation can be used to test the significance of these demographic booms and busts in the context of uncertainty in the radiocarbon date calibration curve and archaeological sampling. We report these results for Central and Northwest Europe between 8,000 and 4,000 cal. BP and investigate the relationship between these patterns and climate. However, we find no evidence to support a relationship. Our results thus suggest that the demographic patterns may have arisen from endogenous causes, although this remains speculative

Reconstructing regional population fluctuations in the European Neolithic using radiocarbon dates: a new case-study using an improved method

In a previous study we presented a new method that used summed probability distributions (SPD) of radiocarbon dates as a proxy for population levels, and Monte-Carlo simulation to test the significance of the observed fluctuations in the context of uncertainty in the calibration curve and archaeological sampling. The method allowed us to identify periods of significant short-term population change, caveated with the fact that around 5% of these periods were false positives. In this study we present an improvement to the method by applying a criterion to remove these false positives from both the simulated and observed distributions, resulting in a substantial improvement to both its sensitivity and specificity. We also demonstrate that the method is extremely robust in the face of small sample sizes. Finally we apply this improved method to radiocarbon datasets from 12 European regions, covering the period 8000–4000 BP. As in our previous study, the results reveal a boom-bust pattern for most regions, with population levels rising rapidly after the local arrival of farming, followed by a crash to levels much lower than the peak. The prevalence of this phenomenon, combined with the dissimilarity and lack of synchronicity in the general shapes of the regional SPDs, supports the hypothesis of endogenous causes

Supply and demand in prehistory? Economics of Neolithic mining in northwest Europe

The extent to which non-agricultural production in prehistory had cost-benefit motivations has long been a subject of discussion. This paper addresses the topic by looking at the evidence for Neolithic quarrying and mining in Britain and continental northwest Europe and asks whether changing production through time was influenced by changing demand. Radiocarbon dating of mine and quarry sites is used to define periods of use. These are then correlated with a likely first-order source of demand, the size of the regional populations around the mines, inferred from a radiocarbon-based population proxy. There are significant differences between the population and mine-date distributions. Analysis of pollen data using the REVEALS method to reconstruct changing regional land cover patterns shows that in Britain activity at the mines and quarries is strongly correlated with evidence for forest clearance by incoming Neolithic populations, suggesting that mine and quarry production were a response to the demand that this created. The evidence for such a correlation between mining and clearance in continental northwest Europe is much weaker. Here the start of large-scale mining may be a response to the arrival by long-distance exchange of high-quality prestige jade axes from a source in the Italian Alps