Field methods and techniques
The present project, based on the excavation of the site of Vale Boi, Algarve, aims to study one key moment of change in the history of human kind: the Neanderthal-Modern Human transition and the emergence of Anatomical Modern Humans (AHM). The main objectives of the project are 1) to date the time and mode of the extinction of Neanderthals and the emergence of AHM in southern Iberia; 2) characterize the elements of modern human cognition, including differences in raw material acquisition and use, lithic and bone technology, use of fire, body ornaments, use of pigments, and mobile art; 3) to determine if the modern traits are unique to Upper Paleolithic or if they are present in the Mousterian; 4) to establish if the appearance of those traits are pre or post use of dietary marine resources; and 5) to investigate the relation between the use of marine resources and the biological human development. This project has three phases: 1) Excavation of Middle and Upper Paleolithic levels at Vale Boi; 2) Absolute dating and analyses of archaeological materials and geoarchaeological data; 3) Model reconstruction for cognitive and symbolic systems of the last Neanderthals and first AMH in the region.
Our goals are to examine: a) intra-site spatial organization across the boundary; b) Subsistence strategies and the emergence of resource intensification, specifically in terms of marine and aquatic resources; c) changes and evolution in the raw material exploitation, lithic technology, heat treatment, and tool function for both chipped and ground stone; e) production techniques and time investment for ornaments and bone tools; f) use, exploitation and technology of pigments. The complete Upper Paleolithic regional sequence is well documented at Vale Boi - this includes Gravettian, Protosolutrean, Solutrean, and Magdalenian, covering a time span between c. 32 and 12 kyr cal BP (Bicho et al., 2010). Vale Boi is over 10,000 m2 with three main areas of occupation: Rockshelter, Terrace, and the Slope, where a series of midden deposits were deposited. While here are signs of some natural disturbance, the Rockshelter and Terrace indicate a pristine and undisturbed sequence. The faunal preservation (both terrestrial and marine) is excellent. Marine fauna, with a few marine mammals and numerous shells of different species, both food and ornamental, are found very early in the sequence. Sediments will also provide valuable information on paleoclimatic data through magnetic susceptibility (Ellwood et al., 2003), sedimentology and geochemical analysis. Terrestrial gastropods may help to study the local and regional climatic changes (Colonese et al., 2009; Craig et al., 2010).
Excavation will use a 1 m2 grid system and 3D coordination, samples and archaeological features using total station equipped with EDM, directly connected to a PC where data are stored and organized (McPherron and Dibble, 2002). The measurements are both precise to within 1 mm, and accurate, since all the measurements are relative to the same point that is connected to standard geographical coordinates (latitude and longitude). Also, this system, together with GIS software, allows a faster and more comprehensible view of artifact distributions. The basic vertical units will be based on geological layers. Each of these will be excavated by 5 cm spits, designated by numbers, starting on the top with level 1. Within each spit, all artifacts and faunal remains are 3D plotted, as long as they are larger than 2 cm. The exceptions in terms of size are bladelets, complete retouched tools, whole shells or adornments that are always plotted.
Lithic analysis will follow methodology developed in the Near East (Ferring 1980; Munday 1979). This methodology is different from that traditional method developed by Bordes, since it uses morphological characteristics from all classes of artefacts (e.g., flakes, blades and bladelets). It is a technological perspective, based on the so-called chaîne opératoire (Geneste, 1983; Pellegrin, 1995) aiming to reproduce the reduction sequences used at the site. Naturally, in addition to this technique, a slower but accurate method will be used – that of the refitting. Use wear research will also take place, consisting on the determination of the tools' function through the changes visible microscopically on their edges and surfaces, resulting from the use of the instruments. As a consequence, this will allow to: (1) identify the tasks that took place at Vale Boi; (2) reconstruct the working processes on the distinct animal, vegetal and mineral materials transformed at the site; (3) identify the occurring technological innovations and changes. Raw material provenience studies will help to characterize the lithic raw materials in use in order to determine its geologic origin. This will be based on rigorous comparisons between geologic samples from well known located sources and artefacts, which will be made through: (1) conventional petrographic analysis of materials (thin sections of tools and samples), and (2) geochemistry using XRF. These analyses will reveal patterns of mineral exploitation, strategies adopted to manage and select different raw materials, organizational strategies of activities related to stone tool production, displacement trajectories of human groups allowing identification of social and economic territories. Analysis of bone tools, ornaments, and pigments will be carried out to understand prehistoric technology as well as to study social and ethnic networks in the area. Both formal and technological aspects will be used, through macroscopic and microscopic research. Aspects such as type of perforation, cutting and grinding will be investigated in this analyses and, in certain cases, replicated for comparative purposes. Subsistence strategies and the local impact of human population on the prey species are the main focus of the zooarchaeological research. Zooarchaeology lays on a series of techniques, related to bone assemblage formation processes (including modification, attrition, diagenesis and chemical preservation), patterns of ungulate mortality, including aspects of gender, age profiles and body part representation, and, finally, changes in dietary breadth through the analysis of number and type of prey species as well as carcass processing intensification. Game and carcass processing is mainly dependent on technology. Technological factors such as the use of fire, storage, preservation, cutting, and pulverizing are fundamental to improve human’s capacity to maximize nutritional value of dietary resources (Lupo & Schmitt 1997; Stiner 2003). It is the case of use of bone marrow. During the Middle Paleolithic, bone marrow was consumed by fracturing long bones of ungulates. During the Upper Paleolithic that technique extended to small game such as lagomorphs (Hockett and Bicho, 2000; Manne and Bicho 2009), but more important, a new technique was invented – bone grease extraction through heat-in-liquid (Binford 1978; Lupo & Schmitt 1997; Stiner, 2003). This technique of rendering fat, present in Vale Boi at least since early Gravettian times raises substantially the amount of protein and fat per carcass when compared with that of the yields obtained by cold marrow extraction. Techniques of faunal analysis will include the common determination of NISP, MNI, MAU and MNE (Lyman, 1994; Reitz and Wing, 1999; Stiner, 2005). A series of analytical procedures will be used to investigate general environmental alterations, namely climatic changes and shore line fluctuations. These include traditional sedimentological analysis, but also micromorphology, magnetic susceptibility (carried out by Ellwood, Louisiana State University) and XRD on bulk mineral composition. In this matter, aspects such as the frequency of organic matter, granulometry, and ratio Sodium/Potassium will help to clarify the oceanic influence in the local deposits, and thus, will serve as a proxy for the alterations in the distance from the site to the shoreline, as well as for the levels of humidity, salinity, temperature and rainfall. Absolute dating will be based on radiocarbon (AMS). A series of other absolute methods such as ESR, luminescence (TL, OSL, and IRSL), U-series enhanced by thermal ionization mass spectrometry (TIMS) may be used if necessary (Mellars, 2006).