The impact of the Neolithic agricultural transition in Britain: a comparison of pollen-based land-cover and archaeological 14C date-inferred population change
Highlights
► Spatially-aggregated demographic and land-cover change for the whole of Britain. ► Transformed pollen records are compared with archaeological 14C date densities. ► Neolithic population growth was accompanied by decreased woodland cover. ► Human impact is the main pace-maker of mid-Holocene land-cover change.
Introduction
Prehistoric agricultural land clearance, burning and deforestation have transformed the landscapes of the British Isles since the Mesolithic–Neolithic agricultural transition around 6000 years ago (∼4000 BC). Evidence of cultural landscape transformation has been preserved in numerous different archives, including archaeological sites and fossil pollen records, which provide information on past vegetation and land-use change. The expansion of agriculture in Europe was strongly linked to the Neolithic demographic transition (Bocquet-Appel et al., 2012). Both demic diffusion by migration and cultural diffusion of ideas are thought to have been important factors in initiating this agricultural shift (Lemmen et al., 2011). The Mesolithic–Neolithic transition in the British Isles (see e.g. Darvill (2010) for standard definitions of these and other period names in Britain) is characterised by a number of key environmental changes and economic shifts (Cayless and Tipping, 2002). These include anthropogenic vegetation disturbance, fluctuating patterns of burning, and the elm (Ulmus) decline (∼5650–5600 cal. BP). Cereal cultivation was one of the earliest elements of Neolithic life to be introduced to Northwest Europe, with the arrival of farming occurring over a 200–300 year period around 6000 BP. Whittle et al. (2011) describe the process of spread of the Neolithic in Britain as time-transgressive and regionalised, beginning in southeast England and taking over two centuries to spread to other areas. However, Bocquet-Appel et al. (2012) demonstrate that compared with most other regions of Europe the spread of farming to and then through Britain was extremely rapid and must have involved sea routes, not just overland expansion (cf. Collard et al., 2010). There are numerous factors that are likely to have influenced the nature and spread of the agricultural transition, and these will have had different impacts and consequences in different regions. Among them, Gronenborn (2009) suggests that the emergence and spread of farming resulted from climate-induced crisis periods.
Research that attempts to address whether the Neolithic transition resulted from demic migration or cultural diffusion, and whether this was gradual or more rapid, has been limited by a focus on single sources of spatially-aggregated data, either archaeological or palaeoecological. Whittle et al. (2011), for example, commented that few archaeological studies of Neolithic subsistence incorporate pollen data, partly due to the geographical disjunction between the varying sets of evidence. Each approach on its own has potential biases and limitations. For example, archaeological radiocarbon (14C) dates derive from a combination of different contexts and site types including domestic settlements, burials and monumental sites, and the balance between these varies temporally and spatially within the archaeological record in later prehistory. Similarly, pollen-inferred vegetation changes during the mid-Holocene had multiple drivers, including climate change and long-term ecological dynamics, as well as anthropogenic impact. It has also been argued (e.g. Brown, 1997) and demonstrated in simulation experiments (Tipping et al., 2009) that regional pollen diagrams lack sufficient spatial resolution to detect isolated clearings and the effects of subtle human impacts. In order to overcome these archive-specific biases, in this study we compare two approaches – pollen-inferred land-cover reconstruction and 14C date distributions from archaeological sites – for Britain as a whole. One advantage of this multi-archive approach is that changes in vegetation and land-use can be directly compared with inferred demographic change on a common calibrated radiocarbon timescale. We also compare these datasets with selected palaeoclimate records in order to explore the prospective roles of human activity and climate in influencing Holocene land-cover change in Britain.
Section snippets
Pollen-inferred land-cover change
Various approaches have been employed to utilise pollen in reconstructing land-cover change (e.g. Behre, 1986; Berglund, 1991; Gaillard et al., 1994; Sugita et al., 1999; Sugita, 2007; Favre et al., 2008). Within the pseudo-biomisation (PBM) approach used here, pollen count data from 14C-dated sediment sequences are transformed into records of natural and culturally-modified land-cover change according to the shifting dominance of different taxa through time (Fyfe et al., 2010). This method
Britain
Significant changes in the pollen-inferred land-cover record are identified as those that persisted for more than one 200 year time slice, and phases that correspond with changes in inferred-population are highlighted. The land-cover reconstruction for the whole of Britain over the last 9000 years (Fig. 3a) shows an overall trend from dominance of deciduous woodland during the early Holocene to increasing landscape openness and diversification during the late Holocene. The percentage of pollen
The Neolithic agricultural transition in Britain
Common trends and timing in land-cover and population density change for the period 9000–3400 cal. BP imply that increases in human population levels and the advent of Neolithic farming systems were the primary cause of the mid-Holocene decline in woodland and increase in open land in Britain. Although this conclusion is far from new at a local scale, it has not been universally accepted at the scale of Britain as a whole, where climate change has been seen by some authors as the most important
Conclusion
The comparisons between pollen-inferred land-cover and archaeo-demographic change presented here have implications for understanding of the Neolithic transition and for the approaches used to investigate anthropogenic activity and environmental change during the mid-Holocene. The multi-archive approach employed here has allowed large-scale human population and vegetation change to be investigated together and provides insights into the impacts of changing demography upon land-cover. The close
Acknowledgements
The development of the pseudo-biomisation approach was supported through Plymouth University Geography PUP funds and Leverhulme Trust grant F/568W. The radiocarbon date work by Downey, Edinborough and Shennan was funded by European Research Council Advanced Grant #249390 for the project EUROEVOL: Cultural Evolution of Neolithic Europe. Thanks are also given to contributors to the European Pollen Database and the authors of the palaeoclimate datasets used in this paper. We are also grateful for
References (44)
- et al.
Mid-Holocene environmental change at Black Ridge Brook, Dartmoor, SW England: a new appraisal based on fungal spore analysis
Review of Palaeobotany and Palynology
(2006) - et al.
Understanding the rates of expansion of the farming system in Europe
Journal of Archaeological Science
(2012) - et al.
Radiocarbon evidence indicates that migrants introduced farming to Britain
Journal of Archaeological Science
(2010) Climate deterioration and land-use change in the first millennium BC: perspectives from the British palynological record
Journal of Archaeological Science
(2006)- et al.
A contribution to deciphering the meaning of AP/NAP with respect to vegetation cover
Review of Palaeobotany and Palynology
(2008) - et al.
Application of modern pollen/land-use relationships to the interpretation of pollen diagrams – reconstructions of land-use history in South Sweden 3000–0 BP
Review of Palaeobotany and Palynology
(1994) - et al.
On the sensitivity of the simulated European Neolithic transition to climate extremes
Journal of Archaeological Science
(2014) - et al.
A simulation of the Neolithic transition in Western Eurasia
Journal of Archaeological Science
(2011) - et al.
Climatic reconstruction in Europe for 18,000 yr BP from pollen data
Quaternary Research
(1998) - et al.
Prehistoric population history: from the Late Glacial to the Late Neolithic in Central and Northern Europe
Journal of Archaeological Science
(2007)