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Pastoralism and camelid management are traditionally attributed to the sociopolitical, economic and cosmovision of Andean populations, rather than to lowland hunter gatherer societies, living on the Pacific coast where camelid hunting is considered a marginal activity, and husbandry is a difficult enterprise given the hyper-arid conditions of lowland terrestrial ecosystems. Contrary to this interpretative historical view, our stable isotope analyses applied to 48 camelid fiber samples, suggests this highly valued camelid byproduct was obtained from camelids sustained on lomas vegetation formations during the Archaic (ca. 6500-4000 cal yr BP), Formative (ca. 4000-1500 cal yr BP) and Late periods (ca. 660-480 cal yr BP).

Camelid caravans have played a key role in the complex systems of interregional social interaction that characterizes Andean history. In the northernmost region of Chile, the most frequent archaeological indicators of these caravan systems are trails and rock art images. Cruces de Molinos (LL-43), a rock art site in the Lluta valley, 1100 masl, 40 km from the Pacific littoral, expands the ceremonial role of rock art sites, materialized, not only as regards the iconography portrayed and alluding to these practices, but also in terms of articulated carcass remains and detached anatomical units of camelids, intentionally deposited in a cache beneath one of the engraved blocks. This paper analyzes the site considering the visual imagery, spatial location, archaeological deposits and features associated with rock art. Based on the predominance of camelid and caravan motifs in rock art images, the extraordinary setting and location of the site on the valley's upper slopes, which is far removed from local settlements, but closely connected with a llama caravan trade network linking the chaupiyunga ecozone with the highlands (sierra and Altiplano ecozones), we suggest that Cruces de Molinos was not a rest stop for caravanners, but a ceremonial place, and not for local farmers, but for highland herders. According to seven accelerator mass spectrometry (AMS) dates that place the occupation between cal. 1060–1190 CE in the Late Intermediate period.

The Altiplano constitutes the most extensive, high-elevation terrain in South America. Most archaeological research on the earliest human occupation of this region in the Bolivian Andes derives from sites such as Viscachani where the emphasis has been on typological comparisons of projectile points, rather than on complete and radiometrically dated assemblages. In this paper, we present survey and excavation data from the Iroco region in the Central Altiplano of Bolivia to address questions related to the adaptive strategies engaged by Archaic Period highland foragers. Specifically, we focus on the nature of mobility, subsistence, and technological strategies, stemmed from principles in human behavioral ecology. Based on data from radiocarbon dates, lithic, and faunal analyses, we suggest that, similar to other mobile foraging societies in arid environments, highland foragers in Iroco engaged in seasonal residential mobility, consumed a broad range of faunal resources, and developed a curated technological toolkit within the context of ameliorated environmental conditions that prevailed during the early Holocene (11,500–8000 cal BP).

Current scientific evidence shows that humans colonized South America at least 15,000 years ago, but there are still many unknown aspects of this process, including the major and minor migratory routes involved, and the pattern of successive occupation of a diverse continental mosaic of ecosystems. In this context, the role of the Andean highlands (≥3400 meters above sea level) has been neglected, because of the supposedly harsh conditions for humans including hypoxia and cold climate. Nevertheless, the environmental and cultural resources available in the high Andes constitutes an important “megapatch” that should be assessed in terms of human settlement patterns. We review the evidence for late Pleistocene/early Holocene hunter-gatherer occupation of one part of this megapatch, the northern Chilean Dry Puna, in its palaeoecological context. We focus on lithic technology, faunal remains, radiocarbon dates, and other archaeological materials related to different social activities, which allow us to suggest that groups of hunter-gatherers organized and adapted their way of life to highland ecosystems through logistical mobility, and curatorial strategies for lithic tool kits that included projectile points and other formalized tools. The morphology and technological processes involved are recognized over vast territories along the high Andes. We identify this material expression as the high south central Andean Archaic hunter-gatherer tradition, which also featured long distance mobile settlement systems and communication processes over this broad and distinct megapatch. More speculatively, we outline the hypothesis that these highland ecosystems constituted a suitable migratory route that may have been key for the early peopling of the continent, and contrast it with the alternative hypothesis of the initially secondary and seasonally intermittent exploitation of this habitat by hunter-gatherers dispersing along the Pacific coastal corridor.

Shell middens, large heaps of refuse materials that are often interspersed with burials, hearths and other cultural features, provide important data regarding the lifestyles of past coastal and maritime dwellers. Despite the abundance of organic materials, radiocarbon ages from shell middens can be a challenge to interpret because marine shells are depleted in radiocarbon with respect to their contemporaneous atmosphere, known as the “reservoir effect” (R). This issue is particularly problematic in regions like the coastal Atacama Desert where the upwelling of subsurface radiocarbon-depleted waters creates a shell “local” reservoir effect (ΔR) with a time-variable intrinsic uncertainty. Here we review and discuss how the dating of diverse materials from these deposits, including the shells themselves, can reveal large shifts between the terrestrial (atmospheric) and marine carbon cycles. Furthermore, a chronology of such shifts can be used as a proxy of upwelling intensity and to help establish the duration of strong versus weak local upwelling episodes. To test and evaluate these ideas, we present a chronology of R and ΔR variations from a 2-m shell midden sequence from Caleta Vitor in northern Chile that spans the middle Holocene, which remains underrepresented by regional ΔR values. The ∼2000 y sequence of Caleta Vitor, located onshore from a major upwelling center, displays dramatic shifts in radiocarbon reservoir effects which we hypothesize are linked to strong changes in the intensity of local upwelling. Further replication of such archaeomalacological records will be key for not only solving methodological problems regarding the dating of coastal sites but can provide further insights into the evolving terrestrial and marine carbon cycles and how these relate to past climate change.

Developing spatially resolved high-resolution datasets of robust long-term changes in human demography constitutes a major challenge for archaeology. One approach is to use the distribution of summed radiocarbon-age probabilities to infer long-term population dynamics (i.e. palaeodemography). However, these can often be biased by preservation potential, site taphonomy or researcher priorities among other aspects, all of which require large datasets to resolve adequately. For this report, we have created such a dataset for the South-Central Andes (16°–25°S), here termed the South Central Andes Radiocarbon (SCAR) database. SCAR spans the last 15,000 years and incorporates ∼1700 14C-dates from 519 archeological sites reported across an extreme bioclimatic gradient that includes the hyperarid coastal Atacama Desert and adjacent cold, high-elevation Altiplano. Among the possible methodological biases, we first evaluated those related to calibration procedures. Otherwise, changes in summed probability curves show no other relevant biases except for possible research interest/priorities that could be responsible for the gaps in the record from the Bolivian altiplano. Our temporally continuous time-series indicates that prehispanic populations exhibited significant demographic changes during the last 13,100 cal BP. Except for coastal populations; most regions show strongly coordinated demographic fluctuations that follow the same major patterns. Thus, we identified two broad scale population events across the South-Central Andes (Atacama inland, Bolivian Altiplano) from 13,100–4000 cal BP and then from 4000 cal BP to the present. In contrast, the Atacama coastal records suggest a different and more variable occupation pattern over the last 13,460 cal BP, which could be driven by the interaction with oceanographic processes (i.e. upwelling). A widespread major decline at 700 cal BP clearly predates the Spanish colonization and occurs in all of our regions. This widespread decline does not appear to be due to methodological biases, and suggests that a population crash occurred before European occupation. Overall, the SCAR database constitutes a valuable proxy for establishing the long-term dynamics of prehistoric societies that inhabited the western Andean slope. Time-series analyses that use SCAR will shed new light on the demographic and cultural dynamics at different spatial-scales, and help clarify the processes involved in the migrational trajectories and cultural evolution of the peoples that inhabited the South-Central Andes over the last 15,000 years.