Showing papers by "Stephen Shennan published in 2017"

Holocene fluctuations in human population demonstrate repeated links to food production and climate.

Abstract: We consider the long-term relationship between human demography, food production, and Holocene climate via an archaeological radiocarbon date series of unprecedented sampling density and detail. There is striking consistency in the inferred human population dynamics across different regions of Britain and Ireland during the middle and later Holocene. Major cross-regional population downturns in population coincide with episodes of more abrupt change in North Atlantic climate and witness societal responses in food procurement as visible in directly dated plants and animals, often with moves toward hardier cereals, increased pastoralism, and/or gathered resources. For the Neolithic, this evidence questions existing models of wholly endogenous demographic boom–bust. For the wider Holocene, it demonstrates that climate-related disruptions have been quasi-periodic drivers of societal and subsistence change.

Climate induced human demographic and cultural change in northern Europe during the mid-Holocene.

Abstract: The transition from hunter-gatherer-fisher groups to agrarian societies is arguably the most significant change in human prehistory. In the European plain there is evidence for fully developed agrarian societies by 7,500 cal. yr BP, yet a well-established agrarian society does not appear in the north until 6,000 cal. yr BP for unknown reasons. Here we show a sudden increase in summer temperature at 6,000 cal. yr BP in northern Europe using a well-dated, high resolution record of sea surface temperature (SST) from the Baltic Sea. This temperature rise resulted in hypoxic conditions across the entire Baltic sea as revealed by multiple sedimentary records and supported by marine ecosystem modeling. Comparison with summed probability distributions of radiocarbon dates from archaeological sites indicate that this temperature rise coincided with both the introduction of farming, and a dramatic population increase. The evidence supports the hypothesis that the boundary of farming rapidly extended north at 6,000 cal. yr BP because terrestrial conditions in a previously marginal region improved.

Data and code for demographic trends in the paper "Human responses and non-responses to climatic variations during the Last Glacial-Interglacial transition in the eastern Mediterranean"

Abstract: We review and evaluate human adaptations during the last glacial-interglacial climatic transition in southwest Asia. Stable isotope data imply that climatic change was synchronous across the region within the limits of dating uncertainty. Changes in vegetation, as indicated from pollen and charcoal, mirror step-wise shifts between cold-dry and warm-wet climatic conditions, but with lag effects for woody vegetation in some upland and interior areas. Palaeoenvironmental data can be set against regional archaeological evidence for human occupancy and economy from the later Epipalaeolithic to the aceramic Neolithic. Demographic change is evaluated from summed radiocarbon date probability distributions, which indicating contrasting – and in some cases opposite - population trajectories in different regions. Abrupt warming transitions at ∼14.5 and 11.7 ka BP may have acted as pacemakers for rapid cultural change in some areas, notably at the start of the Natufian and Pre-Pottery Neolithic cultures. However temporal synchroneity does not mean that climatic changes had the same environmental or societal consequences in different regions. During cold-dry time intervals, regions such as the Levant acted as refugia for plant and animal resources and human population. In areas where socio-ecological continuity was maintained through periods of adverse climate (e.g. Younger Dryas) human communities were able to respond rapidly to subsequent climatic improvement. By contrast, in areas where there was a break in settlement at these times (e.g. central Anatolia), populations were slower to react to the new opportunities provided by the interglacial world.

Regional Demographic Trends and Settlement Patterns in Central Italy: Archaeological Sites and Radiocarbon Dates

Abstract: Data set for "Regional Demographic Trends and Settlement Patterns in Central Italy: Archaeological Sites and Radiocarbon Dates".

The Revolution in Studies of the Neolithic Transition in the West Mediterranean

Abstract: It has long been clear that farming spread into Europe along two different routes, a northern one through the Balkans and Central Europe and a southern one along the northern coast of the Mediterranean. Studies of the northern route represented by the Starcevo–Kőros–Criș complex in the Balkans and then the Linearbandkeramik, from the western Carpathian Basin to the coast of the English Channel, have been well established for decades. Until recently, however, the Mediterranean expansion west of the Aegean was much less known. Far less work had been carried out and the chronological details, especially those concerning the relationship between the Mesolithic and the Neolithic, were very unclear, not least because the vast majority of radiocarbon dates came from cave and rockshelter sites with complex and often disturbed stratigraphies. In particular, the fact that both Mesolithic and Neolithic material were apparently found in the same layers led to the conclusion that the mechanism of the transition in the Mediterranean must have been the gradual and piecemeal adoption of elements of a farming way of life by local foragers. In the last 20 years our knowledge has been transformed. There has been a revolution in the understanding of the spread of farming in the West Mediterranean, especially in Iberia, thanks to the work of a new generation of archaeologists trained in the methods of modern scientific archaeology, from fieldwork to laboratory analysis and computer-based modelling.