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The domestication of plants and the origin of agricultural societies has been the focus of much theoretical discussion on why, how, when, and where this change happened. The 'when' and 'where' have been substantially addressed by bioarchaeology, thanks to advances in methodology and the geographical and chronological scope of evidence. However, the 'why' and 'how' have lagged in explanatory power. Armed with the evidence now available, we can return to theory by revisiting the mechanisms allegedly involved, disentangling their connection to the diversity of trajectories, being those protracted or sudden, and identifying the weight and role of the social and ecological parameters involved. We present the Human-Plant Coevolution (HPC) model, which represent the dynamics of coevolution between a human and a plant population. The model consists of an ecological positive feedback system (mutualism), which can be reinforced by positive evolutionary feedback (coevolution). The model is the result of wiring together relatively simple simulation models of population ecology and evolution, through a computational implementation in R. The HPC model shows that the dynamics producing the neolithisation are diverse and involve multiple factors, as has been widely stressed elsewhere, such as pre-adaptation, environmental change, demographic growth, diversification and intensification of subsistence strategies, among others. However, being a formal model, it also brings clarity to how factors are entangled and what are their effects over the trajectory of both human and plant populations under different conditions. Through the systematic exploration of the parameters of the model, we were able to identify the main causes of agriculture and domestication while capturing other nuances such as the existence of asymmetric dynamics (agriculture without domestication, and vice versa), the increasing dependence between mutualistic populations and the causes of large fluctuations in timing of change.

The concept of Anthropic Activity Markers as ethnography-derived models to interpret archaeological activities has seen a remarkable development in recent years. In this talk we present preliminary results of the MoMArq project, a multidisciplinary project that combines cross-cultural studies with analyses of botanical, physical and chemical proxies to investigate plant-related activities in the past. Ethnography-inspired models are being validated through ethnoarchaeological studies and applied to interpret archaeological contexts. This approach allows for a better identification of how people used domestic spaces in the past for plant-related activities, specifically food processing and consumption.

In this paper, we present a pilot study aimed at investigating the impact of subsistence strategies and environmental pressure on the distribution of ethnographically documented strategies to cope with drought and its effects across 35 current societies in Africa. We use freely accessible ethnographic databases to retrieve data on how a number of African societies deal with the circumstances of drought, and ascertain the impact of geography on their distribution in order to measure possible relationships between them, a set of subsistence choices, and proxies of environmental constraints. We use Canonical Correspondence Analysis to explore the emerging patterns and find that subsistence strategy strongly impacts the choice of drought management strategies, especially if considered with a proxy of local environmental condition. Spatial proximity and aridity per se have only marginal impact, highlighting other relevant processes of cultural transmission that at least partly transcend (a) the intensity of human interaction over geographic gradients and (b) local adaptation primarily dependent on water availability. This study supports the wide applicability of quantitative and replicable methods to cross-cultural evidence on a variety of adaptive strategies and uses ethnographic data to propose new hypotheses that can inform future archaeological research by showing recurrent and non-case-specific choices highlighting resilient practices and adaptive behaviour in Africa., This research and this publication were funded by the Spanish Ministry of Economy and Competitiveness through the project CULM–Modelling plant cultivation in prehistory HAR2016-77672-P, PI Debora Zurro) and by the quality research group of the Generalitat de Catalunya (CaSEs–2017 SGR 212). SB is supported by RAINDROPS, (ERC-Stg-2017, grant agreement no. 759800, PI Carla Lancelotti).

Funder: Leibniz Gemeinschaft, The domestication of plants and the origin of agricultural societies has been the focus of much theoretical discussion on why, how, when, and where these happened. The 'when' and 'where' have been substantially addressed by different branches of archaeology, thanks to advances in methodology and the broadening of the geographical and chronological scope of evidence. However, the 'why' and 'how' have lagged behind, holding on to relatively old models with limited explanatory power. Armed with the evidence now available, we can return to theory by revisiting the mechanisms allegedly involved, disentangling their connection to the diversity of trajectories, and identifying the weight and role of the parameters involved. We present the Human-Plant Coevolution (HPC) model, which represents the dynamics of coevolution between a human and a plant population. The model consists of an ecological positive feedback system (mutualism), which can be reinforced by positive evolutionary feedback (coevolution). The model formulation is the result of wiring together relatively simple simulation models of population ecology and evolution, through a computational implementation in R. The HPC model captures a variety of potential scenarios, though which conditions are linked to the degree and timing of population change and the intensity of selective pressures. Our results confirm that the possible trajectories leading to neolithisation are diverse and involve multiple factors. However, simulations also show how some of those factors are entangled, what are their effects on human and plant populations under different conditions, and what might be the main causes fostering agriculture and domestication.

Numerous and extensive 'Stone Walled Sites' have been identified in southern African Iron Age landscapes. Appearing from around 1200 CE, and showing considerable variability in size and form, these settlements are named after the dry-stone wall structures that characterize them. Stone Walled Sites were occupied by various Bantu-speaking agropastoral communities. In this paper we test the use of pXRF (portable X-ray fluorescence analysis) to generate a 'supplementary' archaeological record where evident stratigraphy is lacking, survey conditions may be uneven, and excavations limited, due to the overall site size. We propose herein the application of portable X-ray fluorescence analysis (pXRF) coupled with multivariate exploratory analysis and geostatistical modelling at Seoke, a southern African SWS of historical age (18th century CE). The aim of the paper is twofold: to explore the potential of the application of a low cost, quick, and minimally invasive technique to detect chemical markers in anthropogenic sediments from a Stone Walled Site, and to propose a way to analyse the results in order to improve our understanding of the use of space at non-generalized scales in such sites., This research is funded by Fundación Palarq, calls 2019 and 2020, project ”Geo-EtnoArqueologia y uso del espacio (GEA)” entrusted to SB. SM and FM received financial support from the Office of Research and Development at the University of Botswana. The work of SGA was funded by the European Union’s MapDung project funded by the EU Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No H2020-MSCA-IF-2017-794823. SB, JAM, ARG, CL and SGA are members of CaSEs Research Group of the Catalan Research Agency (AGAUR SGR-212), which is an associated unit (Unidad Asociada) to the Institucion Mila Y Fontanals of the Spanish Research National Council (CSIC). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.