Due to its complexity, diversity of artifact assemblages, excellent faunal and human bone preservation, and evidence for multiple site function, Cabeço da Amoreira, Muge, is an ideal opportunity to study the emergence of social complexity in Mesolithic complex hunter-gatherers. FCT funding will support excavation (at least 15 weeks with 20 people), and laboratory analysis of lithic and organic artifacts, zooarchaeological research, analysis of humans remains and burial contexts, use wear analysis, raw material provenience studies, DNA and isotope analysis of human remains, and radiocarbon dating. Our goals to understand and define the appearance of social complexity are to examine: a) Subsistence strategies and site function and its relation to social changes; b) Differential distribution among population of prestige items, recognized through the study of burial intra- and inter-spatial patterning; c) Changes and evolution in technology, based on raw material exploitation, reduction sequences and use wear, and its direct relation to spatial organization and diachronic transformations, as well as to social prestige and distribution; d) Cultural and physical alterations in the local population, based on DNA and diet that will provide information on direct genetic links between skeletons.
Various sites dated to the early Holocene were found in Estremadura and northern Alentejo (e.g., Araújo, 2009; Arnaud, 1993; Bicho, 1994; Silva and Soares, 1981), indicating a highly diverse pattern of types and locations of sites, chronologies, technology and subsistence. Bicho has argued for a two phase adaptive evolution in Central Portugal. The Epipaleolithic phase, that started somewhere around 10,500 BP, resulting from an increase in population, with many similarities to the long cultural tradition of the Final Upper Paleolithic, and thus an igualitarian society: same technological traits, similar trends in dietary characteristics, but marked by an intensification of the use of the landscape. The second phase, starting sometime around 8,000 BP, the Mesolithic, saw another demographic pulse and a clear break with the settlement and subsistence patterns as well as technological aspects seen before. The new trend was marked by what is commonly called Complex Hunter-gatherers (e.g., Bailey and Milner, 2003; Erlandson, 2001; Palssen, 1991), also known as Maritime hunter-gatherers: large to very coastal or estuarine large semi-permanent sites; highly logistical mobility system; large burial grounds; large populations; aquatic resources as an important stipend of the diet; emergence of social complexity (but not political), based on differentiation of age or gender, usually indicated by diversity in the burial goods.
Even though some of those aspects were present in Muge (and Sado), traditionally in Portugal, these Mesolithic people are not seen as complex hunter-gatherers, and are just the continuation of the earlier epipaleolithic populations. In fact, it is fairly generalized to call all early Holocene prehistoric occupation of Portugal Mesolithic, without regards for the type of technologic, economic, social and symbolic differences between the two phases. In what concerns the diet, the results from isotopic analyses of the human skeletons indicate the presence of marine proteins that can reach 50% in certain samples. The location of all sites is very close to the estuarine shore during occupation due to the Flandrian transgression in the Atlantic period, and this can help to explain the type of diet. But, the reality is that the marine and estuarine resources were in use for a long time, traditionally believed from the Tardiglacial on (Bicho, 1994; Araujo, 2009), perhaps from Mousterian times (Bicho and Haws, 2008) . So why would the settlement system change since Boreal times to the Atlantic phase? Perhaps the answer (Bicho et al, in press) is in the increase estuarine biomass and the geomorphologic changes due to the 8.2 K cold event (Grafstein et al., 1998; Barber et al., 1999; Mcdermott, et al, 2001), with the collapse of the Hudson Ice Dome causing a freshwater cold pulse that reached Portugal. Another issue is raised by two different types of data, and it is related to settlement patterns and populations dynamics.
The trace element and isotopic data clearly suggests that the diet was not the same in each site and since the isotopic elements present in the bones reflect at least the last 7 years of the individual and the results are different among sites, it means that the same people did not use all sites, and that they did not belong to the same settlement system and neither to the same group. In this case, the high number of sites in the Muge region does not reproduce the whole settlement system of those populations, and we are still missing sites that would complete the living system of the region. The other point is that the burial grounds are located in the living sites. It is difficult to believe that the same site was used at the same time for both living and dead people (and there is not unequivocal evidence to think that those sites had only a symbolic and religious purpose). In fact, we now known that each site was used for more than one task (e.g., living, hunting, gathering shellfish, processing fish, burying the death), but not all tasks at the same time. We also know, based on the recent excavations of Cabeço da Amoreira, that each shellmidden had a series of loci directly around the midden, distancing between 20 and 50 meters: in the case of Cabeço da Amoreira there are at least 3 of those loci that were occupied during Mesolithic and Neolithic times and had no shells. The logical outcome then is that the settlement pattern was more complex that we previously thought and that we are still missing sites and types of sites. Following this idea, in the previous project, we were able to discover a series of new sites, partially or completely destroyed, but that helped to reconstruct the settlement system during the Mesolithic (Bicho 2009; Gonçalves, 2009): large shellmiddens distancing c. 750 meters from each other are located up to the limit of the extension of salt water (Van der Schriek, et al., 2008), and in general situated right in front of each other on both sides of the valley. Using archaeological and ethnographic analogy there seems to be a clear tendency for the presence of social inequality and the emergence of complexity: the sites are located in a orderly fashion, all at the same distance from each other, located in front of each other on both sides of the valley, reflecting the social separation of a clanic and lineage separation seen at the Anasazi site of Pueblo Bonito (Chaco Canyon, American Southwest - Van Dike, 1999; Vivian 1970); the results from the isotopic and trace-elements point to a intra and inter-site diversity diet as well as diachronic differences, that could be easily explained by individual movements within the region of the linguistic community, but also between lineages and families that were identified by family name as seen in the !Kung (Ju/’hoansi) from the Kalahari (Yellen, 1977); and finally, the case of Moita do Sebastião where burials at the basis of the shellmidden show a clear spatial organization (Fig 1 attached)with two distinct areas, northwest and southwest: while the first area has various burials with prestige items (one side with perforated shells and the other side with lithic artefacts, suggesting a separation based on gender?) (Bicho, 2009b), the second area does not have any prestige goods except for a child burial. This is very much identical to the burial ground with the same chronology, in the Lake Onega near the Baltic Sea in Russia, Oleni Ostrov. There the spatial arrangement and the prestige goods found in the human burials were interpreted as the appearance of social complexity based on age, gender, clan and lineage systems (Jacobs, 1995; Popova, 2001).
So in summary, this project would test the hypothesis that the new ecological setting and population aggregation on both sides of the Muge valley, around 8,2 cal BP, resulted in a complex hunter-gatherer settlement, economic and social system with large sites with small satellite sites around them, with large burial grounds with evidence of social inequalities, perhaps based on age, gender, but certainly based on clans, lineages or moities, reflected in the presence of prestige items in burials, spatially separated from others without them, as well as on the site distribution and location. This research is based on the study of dietary elements (zooarchaeology and isotopic and trace-element analysis), genetic links between skeletons (DNA studies carried out in Madrid); technological changes and use of prestige goods such as exotic raw-materials (technological analysis, use-wear and raw- material provenience with XRF and petrography); and spatial analysis of site and burials (with GIS).