Pastoral Geo-Ethnoarchaeology. Micromorphology and biogeochemistry of dung deposits in mobile societies
The main goal of this dissertation is to provide a robust, innovative analytical methodology for the accurate detection and characterisation, at the microscopic and molecular scale of analysis, of organic-rich anthropic sediments from contemporary nomadic pastoral sites, with special focus on dung deposits. This research provides new data for the archaeological investigation of mobile pastoral habitation sites, and contributes to current approaches in the archaeology of pastoralism. Pastoral societies have been, since the origins of domestication, an exceptional example of adaptation and resilience. Nowadays, nomadic pastoralism and transhumant activities supports more than 200 million people globally in a range of different environmental settings: from humid high mountains to arid deserts. The study of past pastoral societies through microscopic analysis in soils and sediments has been a recurrent topic of geoarchaeological research. Since the 1980s, methodological and technical advances in palaeobotany and geoarchaeology contributed to consolidate a robust analytical toolkit, including, among others, 1) soil micromorphology, 2) pollen analysis, 3) carbonized seed remains and 4) phytolith analysis. These techniques, used alone or in combination, have provided relevant information on past pastoral livestock. However, high-resolution analytical approaches are needed to fully characterise and understand domestic spaces and specific activities associated with animal husbandry, such as intensity of livestock penning, re-use, cleaning, breaking of dung deposits, corralling of different livestock species, and seasonality of foddering. Organic matter (mainly composed of cellulose, proteins, chitin, lipids and lignin) mixed in the soils is a unique source of detailed information on the past. Its presence in archaeological contexts is many times underestimated because it is not visible to the eye, especially in high erosional environments. In recent years, advances in biomolecular analyses applied to archaeological research, such as lipid and stable isotope biogeochemistry, have provided new anthropic and animal biomarkers that offer promising insights on past subsistence strategies and mobility patterns. These analyses have been mostly applied to artefacts and biological remains (i.e. pottery, bones and teeth), although the experimentation of lipid and stable isotope biogeochemistry applied to organic-rich sediments remains seldom investigated. Only recently, studies focusing on herbivore faecal remains have shown the importance of excrements and their implication for identifying socio-economic activities in archaeology. Therefore, an accurate microstratigraphic and molecular examination of these deposits can provide us new insights into past activity areas, landscape land use, site formation processes, domestic use of fuel, manuring and stabling or foddering strategies. Micromorphology of soil sediments, lipid analysis and compound specific stable isotopes analysis are useful scientific techniques that combined with archaeology and ethnography allows identification of herd penning and multi-resource economic strategies dynamics, that are crucial to understand living conditions and diet of humans and animals in Pre- and Protohistory. This research uses an innovative combination of state-of-the-art methods that will combine and statistically treat multiple proxy sources from sediments, animal dung and plants. Through the presentation of four scientific articles, this thesis focuses on three different-case scenarios: a well-preserved Neolithic organic-rich cave deposit in the European Mediterranean region; a well-preserved organic-rich open-air ethnoarchaeological hyper-arid deposit in North Africa; and a well-preserved organic-rich open-air ethnoarchaeological hyper-continental deposit in Central Asia. These case studies represent an ideal setting to compare different taphonomical processes affecting the organic accumulations. The novel integration of soil micromorphology, bulk stable isotope analysis (δ13C, δ15N), lipid analysis (n-alkanes) and δ13C stable isotope analysis of n-alkanes in different anthropic deposits validates the proposed methodology in diverse ecological habitats and provides contextualised and quantifiable high-resolution data that goes well beyond current approaches in geoarchaeological research.