This paper reports on several experiments carried out to explore the transformations of the archaeological record affected by trampling. These transformations include changes in artifact distributions and formal alterations that should be taken into account when carrying out studies of activity areas. The experiments were made on dry, hard-packed surfaces and in the same sediments after a rain. The materials used were bones, obsidian flakes, sherds, and fragments of brick and wood. The analysis focuses on vertical displacement, horizontal displacement, and damage (breakage, microflaking, and abrasion), paying special attention to the response of the trodden substrate and its implications for the whole process. The interaction of trampling with other formation processes (e.g., maintenance) also is considered. The main patterns observed in the trampled materials are vertical and horizontal size sorting, and characteristic size distributions in sherds. These empirical generalizations are then integrated in a model that can help to identify trampled contexts and assess their potential for behavioral inference.

Important developments in the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) technique have generated new perspectives regarding SNP genotyping, which are particularly promising for ancient population-based studies. The main aim of the present study was to investigate the application of a MALDI-TOF MS-based SNP genotyping technique, called iPLEX(®) Gold, to analyze Amerindian ancient DNA samples. The first objective was to test the sensitivity of the method, which is recommended for DNA quantities between 10 and 5 ng, for ancient biological samples containing DNA molecules that were degraded and present in minute quantities. The second objective was to detail the advantages of this technique for studies on ancient populations. Two multiplexes were designed, allowing the major Amerindian mitochondrial and Y haplogroups to be determined simultaneously. This analysis has never been described before. Results demonstrated the reliability and accuracy of the method; data were obtained for both mitochondrial and nuclear DNA using picogram (pg) quantities of nucleic acid. This technique has the advantages of both MS and minisequencing techniques; thus, it should be included in the protocols for future ancient DNA studies.

The aim of this paper is to generate information to assist in the archaeobotanical recognition of post-harvest processing activities related with different enhancement and consumption patterns of quinoa in the Central Andes. Enhancement of the grains involves what local people call "mejorado de los granos". Their main purpose is to reduce as far as possible the presence of saponins, a toxic metabolite, in the grain. Ethnobotanical data were recorded in the village of Villa Candelaria (Southern Bolivian highlands) through the application of standard ethnographic techniques. The types of grain enhancement vary depending on the meal that people want to prepare. We registered three different quinoa enhancements based on intended consumption, (1) as a whole seed, (2) in soups or (3) as pitu (a kind of toasted refined flour). Laboratory analysis aimed at identifying distinctive features of grains in different processing stages, as well as evaluating the effects of charring. For both desiccated and charred remains, quinoa processed for pitu can be distinguished from that for whole seed/soup. As a case study, archaeological grains of the preInka site of Churupata, located 3 km from Villa Candelaria, were interpreted as quinoa prepared for consumption as whole seed/soup.

Based on archaeological data, we discuss the various ways in which herding and herders articulated with other activities and actors in the South Andes during the last few centuries before the Spanish conquest of America. This relationship took different forms, including pastoral specialization and inter-ethnic trade, political/ethnic integration and redistribution, and economic diversification at a household level. This variability cannot be entirely accounted by environmental diversity, but was also a consequence of changing historical conditions, such as those related to endemic warfare during the fourteenth century or the integration of the area into the Inka state. In each of these scenarios, pastoralists found different ways of integrating with the non-pastoral world, both in practice and representation.

SummaryThis palaeogenetic study focused on the analysis of a late prehispanic Argentinean group from the Humahuaca valley, with the main aim of reconstructing its (micro)evolutionary history. The Humahuaca valley, a natural passageway from the eastern plains to the highlands, was the living environment of Andean societies whose cultural but especially biological diversity is still poorly understood. We analyzed the DNA extracted from 39 individuals who populated this upper valley during the Regional Development period (RDP) (between the 11th and 15th centuries CE), to determine their maternal and paternal genetic ancestry. Some mitochondrial and Y-chromosomal haplotypes specific to the Andean region are consistent with an origin in the highlands of Central Andes. On the other hand, a significant genetic affinity with contemporary admixed communities of the Chaco area was detected. Expectedly, recent demographic events, such as the expansion of the Inca Empire or the European colonization, have changed the original mitochondrial gene pool of the ancient Humahuaca Valley community. Finally, we identified a particular geographical organization of the prehispanic populations of Northwestern Argentina. Our results suggest that the communities of the region were divided between two different spheres of interaction, which is consistent with assumptions made by means of craniometric traits.