Modelling Demic and Cultural Diffusion - An Introduction

Identifying the processes by which human cultures spread across different populations is one of the most topical objectives shared amongst different fields of study. Seminal works have analysed a variety of data and attempted to determine whether empirically observed patterns are the result of demic and/or cultural diffusion. This special issue collects papers exploring several themes (from modes of cultural transmission to drivers of dispersal mechanisms) and contexts (from the Neolithic in Europe to the spread of computer programming languages), which offer new insights that will augment the theoretical and empirical basis for the study of demic and cultural diffusion. In this introduction we outline the state of art in the modelling of these processes, briefly discuss the pros and cons of two of the most commonly used frameworks (i.e. equation-based models and agent-based models), and summarise the significance of each paper published in this special issue

Reassessing the role of climate change in the Tupi expansion (South America, 5000–500 BP)

The expansion of forest farmers across tropical lowland South America during the Late Holocene has long been connected to climate change. The more humid conditions established during the Late Holocene are assumed to have driven the expansion of forests, which would have facilitated the dispersal of cultures that practised agroforestry. The Tupi, a language family of widespread distribution in South America, occupies a central place in the debate. Not only are they one of the largest families in the continent, but their expansion from an Amazonian homeland has long been hypothesized to have followed forested environments wherever they settled. Here, we assess that hypothesis using a simulation approach. We employ equation-based and cellular automaton models, simulating demic-diffusion processes under two different scenarios: a null model in which all land cells can be equally settled, and an alternative model in which non-forested cells cannot be settled or delay the expansion. We show that including land cover as a constraint to movement results in a better approximation of the Tupi expansion as reconstructed by archaeology and linguistics.info:eu-repo/semantics/publishedVersio

Summed Probability Distribution of 14C Dates Suggests Regional Divergences in the Population Dynamics of the Jomon Period in Eastern Japan.

Recent advances in the use of summed probability distribution (SPD) of calibrated 14C dates have opened new possibilities for studying prehistoric demography. The degree of correlation between climate change and population dynamics can now be accurately quantified, and divergences in the demographic history of distinct geographic areas can be statistically assessed. Here we contribute to this research agenda by reconstructing the prehistoric population change of Jomon hunter-gatherers between 7,000 and 3,000 cal BP. We collected 1,433 14C dates from three different regions in Eastern Japan (Kanto, Aomori and Hokkaido) and established that the observed fluctuations in the SPDs were statistically significant. We also introduced a new non-parametric permutation test for comparing multiple sets of SPDs that highlights point of divergences in the population history of different geographic regions. Our analyses indicate a general rise-and-fall pattern shared by the three regions but also some key regional differences during the 6th millennium cal BP. The results confirm some of the patterns suggested by previous archaeological studies based on house and site counts but offer statistical significance and an absolute chronological framework that will enable future studies aiming to establish potential correlation with climatic changes.Marie-Curie Intra-European Fellowship (Grant ID: 625863), SimulPast Project (Consolider-Ingenio CSD2010-00034)This is the final version of the article. It first appeared from the Public Library of Science via http://dx.doi.org/10.1371/journal.pone.015480

Site Formation Processes and Hunter-Gatherers Use of Space in a Tropical Environment: A Geo-Ethnoarchaeological Approach from South India.

Hunter-gatherer societies have distinct social perceptions and practices which are expressed in unique use of space and material deposition patterns. However, the identification of archaeological evidence associated with hunter-gatherer activity is often challenging, especially in tropical environments such as rainforests. We present an integrated study combining ethnoarchaeology and geoarchaeology in order to study archaeological site formation processes related to hunter-gatherers' ways of living in tropical forests. Ethnographic data was collected from an habitation site of contemporary hunter-gatherers in the forests of South India, aimed at studying how everyday activities and way of living dictate patterns of material deposition. Ethnoarchaeological excavations of abandoned open-air sites and a rock-shelter of the same group located deep in the forests, involved field observations and sampling of sediments from the abandoned sites and the contemporary site. Laboratory analyses included geochemical analysis (i.e., FTIR, ICP-AES), phytolith concentration analysis and soil micromorphology. The results present a dynamic spatial deposition pattern of macroscopic, microscopic and chemical materials, which stem from the distinctive ways of living and use of space by hunter-gatherers. This study shows that post-depositional processes in tropical forests result in poor preservation of archaeological materials due to acidic conditions and intensive biological activity within the sediments. Yet, the multiple laboratory-based analyses were able to trace evidence for activity surfaces and their maintenance practices as well as localized concentrations of activity remains such as the use of plants, metals, hearths and construction materials.The research leading to these results has received funding form the People Programme (Marie Curie Actions—http://ec.europa.eu/research/mariecurieactions/) of the European Union’s Seventh Framework Programme (FP7/2007-2013) under REA agreement n° 623293 granted to DF at the McDonald Institute for Archaeological Research, University of Cambridge. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.This is the final version of the article. It first appeared from PLOS via https://doi.org/10.1371/journal.pone.016418

Millets and Herders: The Origins of Plant Cultivation in Semiarid North Gujarat (India)

Botanical evidence suggests that North Gujarat (India) was a primary center of plant domestication during the mid-Holocene. However, lack of systematic archaeobotanical research and significant taphonomic processes have so far hampered the possibility of substantiating this hypothesis. This paper explores the role of plants in the subsistence strategies of early-middle Holocene populations in this semiarid region and the processes leading to plant cultivation. To do so, we carry out a multiproxy archaeobotanical study —integrating macro and microbotanical remains— at two hunter-gatherer and agropastoral occupations. The results show that the progressive weakening of the Indian summer monsoon ca. 7,000 years ago compelled human populations to adopt seminomadic pastoralism and plant cultivation, which resulted in the domestication of several small millet species, pulses, and sesame.Peer Reviewe

Testing the resilience of agro-pastoralists communities in arid margins through ABM

This paper presents the latest model developed within Case Study 1 (hereafter CS1) of the SimulPast project: Hunter-Gatherer persistence in arid margins. The case of North Gujarat (India). The aim of this model is to test the resilience of agro-pastoralists (AP) communities in semi-arid ecosystems. We created a simple Agent Based Model in which agents relied on a pure subsistence strategy based on domesticated plants and animals. We tested our model against previously published climatic record for the area and concluded that a pure agropastoral strategy was not enough to sustain the population in conditions of high climatic variability. Further tests were performed to check the climatic conditions in which this type of subsistence strategy is self-sustained in order to extrapolate the model to areas with different specificities than the one understudy

INVESTIGANDO A HISTÓRIA DA VEGETAÇÃO (LINHAS DE ÁRVORES) NOS ALPES CENTRAIS: CONTRIBUIÇÕES DA ANÁLISE DE FITÓLITOS

As variações de altitude na linha de árvores nos Alpes durante o Holoceno foram investigadas principalmente por meio de análises de grãos de pólen e de macrofósseis de plantas. Atualmente é consenso que a floresta atingiu altitudes entre 2.400 e 3.000 metros (acima do nível do mar) durante o Ótimo Climático Atlântico (100 a 300metros acima da altitude atual). Essa ideia tem sido discutida há alguns anos e agora novas técnicas são necessárias para resolver este debate. Os solos alpinos podem atuar como arquivos de informações consideradas adequadas para a reconstrução da história da vegetação. Neste trabalho discute-se o potencial dos 5 fitólitos preservados no solo como marcador da história da vegetação alpina em ambientes terrestres secos. O conteúdo de saílica biogênica no perfil de solo estudado mostrou-se baixo no horizonte eluvial e maior em profundidade. A concentração de células curtas de gramíneas apresentou pico na parte superior do perfil e drástica diminuição em direção à base do horizonte eluvial. Morfotipos poliédricos de fitólitos foram os mais comuns na base do perfil de solo. Esta abundância pode ser explicada pela dissolução da opala mais solúvel das monocotiledôneas, ou pode ser uma genuína assinatura da presença de espécies arbóreas. Esta segunda hipótese foi confirmada por meio das análises de EDX que demonstrou ser uma poderosa ferramenta para distinguir morfotipos não idiomórfico (not –idiomorfic)

Global-scale comparisons of human land use: developing shared terminology for land-use practices for global change

Although archaeological data are needed to understand the impacts of past human land use on the Earth system, synthesis is hampered by a lack of consistent categories. We develop hierarchical and scalable land-use classifications for use across the globe

Quantifying the relationship between food sharing practices and socio-ecological variables in small-scale societies: A cross-cultural multi-methodological approach

This article presents a cross-cultural study of the relationship among the subsistence strategies, the environmental setting and the food sharing practices of 22 modern small-scale societies located in America (n = 18) and Siberia (n = 4). Ecological, geographical and economic variables of these societies were extracted from specialized literature and the publicly available D-PLACE database. The approach proposed comprises a variety of quantitative methods, ranging from exploratory techniques aimed at capturing relationships of any type between variables, to network theory and supervised-learning predictive modelling. Results provided by all techniques consistently show that the differences observed in food sharing practices across the sampled populations cannot be explained just by the differential distribution of ecological, geographical and economic variables. Food sharing has to be interpreted as a more complex cultural phenomenon, whose variation over time and space cannot be ascribed only to local adaptation.Spanish Ministry of Science, Innovation and Universities: SimulPast Project (CSD2010-00034 CONSOLIDER-INGENIO 2010), (VA, JC, EB, DZ, MM, JMG), Consolider Excellence Network (HAR2017-90883-REDC) (VA, JC, EB, DZ, MM, JMG), and CULM Project (HAR2016-77672-P)(DZ, JC, MM)