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Optically stimulated luminescence (OSL) measurements are reported for single grains of quartz from deposits within Sibudu rock shelter. Such measurements enable rejection of unrepresentative grains and application of the finite mixture and central age models to obtain the most reliable age estimates. Three types of single-grain equivalent dose (De) distributions were observed: one sample represented a single dose population, three samples indicated mixing between Iron Age (IA) and Middle Stone Age (MSA) deposits, and 10 samples (in addition to the three mixed samples) showed scattered distributions. The latter type resulted from differences in the beta dose received by individual grains. For these samples, the beta doses were modelled and adjusted accordingly. Ages for the 14 samples collected from MSA deposits post-dating the Howiesons Poort (HP) resulted in three age clusters, which are stratigraphically consistent with the three informally named cultural phases at Sibudu: namely, the post-HP, late MSA and final MSA. Weighted mean ages of 58.5 ± 1.4 ka, 47.7 ± 1.4 ka and 38.6 ± 1.9 ka were calculated for these phases, respectively. The three phases were separated by two occupational hiatuses with durations of 10.8 ± 1.3 ka and 9.1 ± 3.6 ka. We hypothesise that the punctuated presence of humans at Sibudu was determined by large-scale fluctuations in climate during oxygen isotope stage (OIS) 3, which resulted in alternating wet and dry periods. Phases of occupation correspond to wet periods when fresh water was available in the Tongati River, whereas intervals of site abandonment correspond to dry periods when people were forced to migrate in search of a reliable source of fresh water. Where people migrated to, remains unresolved.  相似文献   
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Bitumen, found in abundance in Mesoamerica’s southern Gulf Coast region in natural seeps and in many archeological contexts, is an important economic resource and exchange item that has received little consideration in Mesoamerica. Analyses of archeological, ethnoarcheological, and experimental data provide insights on the organization of bitumen processing activities, and the end product (archeological bitumen), which the Olmec (1200–400 BC) used in the production of many items. Archeological data are derived from investigations at El Remolino and Paso los Ortices— two Early Formative period levee sites in the San Lorenzo Olmec region. Our findings suggest that among the Olmec, bitumen processing was organized as a specialized activity, involving multiple production stages, but not necessarily elite involvement or control.  相似文献   
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The Mesolithic–Neolithic transition in north-west Europe has been described as rapid and uniform, entailing a swift shift from the use of marine and other wild resources to domesticated terrestrial resources. Here, we approach the when, what and how of this transition on a regional level, using empirical data from Öland, an island in the Baltic Sea off the Swedish east coast, and also monitor changes that occurred after the shift. Radiocarbon dating and stable carbon and nitrogen isotope analyses of bones and teeth from 123 human individuals, along with faunal isotope data from 27 species, applying to nine sites on Öland and covering a time span from the Mesolithic to the Roman Period, demonstrate a great diversity in food practices, mainly governed by culture and independent of climatic changes. There was a marked dietary shift during the second half of the third millennium from a mixed marine diet to the use of exclusively terrestrial resources, interpreted as marking the large-scale introduction of farming. Contrary to previous claims, this took place at the end of the Neolithic and not at the onset. Our data also show that culturally induced dietary transitions occurred continuously throughout prehistory. The availability of high-resolution data on various levels, from intra-individual to inter-population, makes stable isotope analysis a powerful tool for studying the evolution of food practices.  相似文献   
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Tanzania Maasai began large‐scale urban labour migration in the mid‐1990s, impelled by livestock losses from disease, drought and land alienation. Although they were readily hired in cities as night watchmen and security guards, many urban citizens expressed condescending views of the migrants, typifying them as ‘unmodern’, and as curious young warriors who were lazy, naive, drunk and dirty. Interviews with about 200 Maasai proved these discursive characterizations to be largely incorrect. Although the State has tried over the last century to ‘develop’ and settle semi‐nomadic pastoralists, the Maasai image is widely used as part of an instrumentalist agenda, to advertise items from telephones to tourism. Lacking political or social capital, the migrants manipulate and reinforce Maasai identity by continuing to wear traditional garments (illkarash), and by engaging in practices that emphasize their difference from the ‘WaSwahili’, bolster cohesion and solidarity among themselves, and increase their chances of urban employment.  相似文献   
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Biocultural patterns surrounding the emergence of agriculture from 11 sites in the central Tombigbee River valley (500–1200 AD), 50–100 km west of the emerging Moundville polity, suggest that while food production may have alleviated some ecological stress, it came at a cost. Markers of childhood arrest indicate earlier weaning, likely creating a cycle of rising fertility and competition, but surviving adults appear better off following intensification. Health disparities at farmsteads, including more prevalent anemia, growth defects, lower limb infections, and accidental trauma, are consistent with increasingly competing demands of domestic and corporate modes of production. Although these agricultural settlements in the hinterlands were not severely compromised as predicted by a strictly top down model of provisioning, health risks assumed by farmsteads may have resulted from provisioning to centers and/or corporate lineages while simultaneously mitigating larger risks (e.g., raiding). The greater health risks assumed by farmstead females suggest that they had less control over production and decision-making than women buried at centers, while height and upper body strength at mound centers, in addition to rare but extreme trauma, point to identities that were mapped not only onto the landscape, but onto the bodies of men and women occupying elite spaces.  相似文献   
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