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The nature and extent of the Tiwanaku state expansion in the Andes during the second half of the first millennium AD continues to be debated. Here, the authors report on the recent discovery of an archaeological complex 215km south-east of Tiwanaku, where a large, modular building with an integrated, sunken courtyard strongly resembles a Tiwanaku terraced platform temple and demonstrates substantial state investment. Constructed, the authors argue, to directly control inter-regional traffic and trade between the highlands and the eastern valleys of Cochabamba, the complex represents a gateway node that effectively materialised the power and influence of the Tiwanaku state. 

For centuries the Cerro Rico of Potosí in the South American Andes has been known as the richest silver mine in the world but also as a notoriously challenging place for human habitation due to its extreme elevation. Nevertheless, little is known about the temporal depth and socioecological dynamics associated with the initial occupation of this region. In this paper, we present an archaeological and paleoecological assessment of the earliest human peopling of Potosí and the eastern south-central Andes. Systematic surveys in two neighboring regions complemented by test excavations, artifact analysis, and radiocarbon dating revealed evidence of foraging occupations dating to the Early Holocene as well as by agropastoralist communities during the Late Holocene. Local paleoenvironmental records suggest that periods of increased humidity might have fostered ecological productivity that incentivized settlement in this high elevation setting. The nature of the occupations and associated technological organization is consistent with findings from sites elsewhere in the arid Andes. 

The Late-Holocene history of hydroclimatic variability in the Atacama Desert offers insights into the effects of precipitation and humans on ecosystems in one of the most extremely arid regions of the world. However, understanding the effects of regional precipitation variability in relation to local ecological stressors remains to be fully resolved. Here, we present a pollen-based qualitative precipitation reconstruction derived from fossil rodent middens recovered from two sites near Laguna Roja (LRO; n = 25) and Isluga (ISL; n = 15) in the Atacama highlands (19°S) of northern Chile. At LRO, the fossil pollen record shows multi-centennial hydroclimatic anomalies during the last millennium, with wetter than present phases at 1155–1130, 865–670, and 215–80 cal yrs BP, and similar to present conditions between 1005 and 880 cal yrs BP. In contrast, the ISL record shows a wet phase during 1115–840 cal yrs BP, suggesting that meso-ecological processes were as important in vegetation turnover as regional hydroclimate anomalies. Wetter conditions derived from LRO partially overlap with the Medieval Climate Anomaly (865–670 cal yrs BP) and with the latest part of the Little Ice Age (215–80 cal yrs BP). Furthermore, no strong anthropogenic signal was identified possibly related to the remote location of the records. Palynological diversity analyses evidence increasing diversification of plant communities during wet events at both sites. In correlation to existing regional hydroclimatic records from the Western Andes, our precipitation reconstruction verifies that centennial-scale changes in the strength of the South American Summer Monsoon (SASM) and partial influence of El Niño-like (ENSO) conditions drove vegetation turnover in the Atacama Desert during the last millennium. 

The La Prele Mammoth site (48CO1401), located in Converse County, Wyoming, contains a Clovis-age occupation associated with the remains of a subadult mammoth (Mammuthus columbi). In this paper, we present the geochronological and geoarchaeological context of the site. The La Prele Mammoth site is buried in an alluvial terrace of La Prele Creek, a tributary of the North Platte River, which acts as an important migration corridor through the Rocky Mountains. Archaeological remains, buried by a series of flood deposits, occur within or below a well-developed buried A horizon, referred to as the Mammoth Soil. Bioturbation of the site has resulted in vertical artifact movement, though peaks in artifact density are evident in vertical artifact distributions and likely represent the occupation surface. Radiocarbon dating of this occupation, including several new dates, suggests an age of 12,941 ± 56 calendar years ago (cal yr BP). 

South America is a megadiverse continent that witnessed the domestication, translocation and cultivation of various plant species from seemingly contrasting ecosystems. It was the recipient and supplier of crops brought to and from Mesoamerica (such as maize and cacao, respectively), and Polynesia to where the key staple crop sweet potato was exported. Not every instance of the trans -ecological expansion of cultivated plants (both domesticated and wild), however, resulted in successful farming. Here, we review the transregional circulation and introduction of five food tropical crops originated in the tropical and humid valleys of the eastern Andes—achira, cassava, ahipa , sweet potato, and pacay—to the hyper-arid coastal valleys of the Atacama Desert of northern Chile, where they have been found in early archeological sites. By means of an evaluation of the contexts of their deposition and supported by direct radiocarbon dating, stable isotopes analyses, and starch grain analysis, we evaluate different hypotheses for explaining their introduction and adaptation to the hyper-arid soils of northern Chile, by societal groups that after the introduction of cultigens still retained a strong dependence on marine hunting, gathering and fishing ways of life based on wide variety of marine coast resources. Many of the studied plants were part of a broader package of introduced goods and technological devices and procedures, linked to food, therapeutic medicine, social and ritual purposes that transformed previous hunter-gatherer social, economic, and ideological institutions. Based on archeological data, we discuss some of the possible socio-ecological processes involved in the development of agricultural landscapes including the adoption of tropical crops originated several hundred kilometers away from the Atacama Desert during the Late Holocene. 

The Lake Titicaca basin was one of the major centers for cultural development in the ancient world. This lacustrine environment is unique in the high, dry Andean altiplano , and its aquatic and terrestrial resources are thought to have contributed to the florescence of complex societies in this region. Nevertheless, it remains unclear to what extent local aquatic resources, particularly fish, and the introduced crop, maize, which can be grown in regions along the lakeshores, contributed to facilitating sustained food production and population growth, which underpinned increasing social political complexity starting in the Formative Period (1400 BCE to 500 CE) and culminating with the Tiwanaku state (500 to 1100 CE). Here, we present direct dietary evidence from stable isotope analysis of human skeletal remains spanning over two millennia, together with faunal and floral reference materials, to reconstruct foodways and ecological interactions in southern Lake Titicaca over time. Bulk stable isotope analysis, coupled with compound-specific amino acid stable isotope analysis, allows better discrimination between resources consumed across aquatic and terrestrial environments. Together, this evidence demonstrates that human diets predominantly relied on C 3 plants, particularly quinoa and tubers, along with terrestrial animals, notably domestic camelids. Surprisingly, fish were not a significant source of animal protein, but a slight increase in C 4 plant consumption verifies the increasing importance of maize in the Middle Horizon. These results underscore the primary role of local terrestrial food resources in securing a nutritious diet that allowed for sustained population growth, even in the face of documented climate and political change across these periods. 

Abstract A key concern regarding current and future climate change is the possibility of sustained droughts that can have profound impacts on societies. As such, multiple paleoclimatic proxies are needed to identify megadroughts, the synoptic climatology responsible for these droughts, and their impacts on past and future societies. In the hyperarid Atacama Desert of northern Chile, many streams are characterized by perennial flow and support dense in-stream wetlands. These streams possess sequences of wetland deposits as fluvial terraces that record past changes in the water table. We mapped and radiocarbon dated a well-preserved sequence of in-stream wetland deposits along a 4.3-km reach of the Río San Salvador in the Calama basin to determine the relationship between regional climate change and the incision of in-stream wetlands. The Río San Salvador supported dense wetlands from 11.1 to 9.8, 6.4 to 3.5, 2.8 to 1.3, and 1.0 to 0.5 ka and incised at the end of each of these intervals. Comparison with other in-stream wetland sequences in the Atacama Desert, and with regional paleoclimatic archives, indicates that in-stream wetlands responded similarly to climatic changes by incising during periods of extended drought at ~9.8, 3.5, 1.3, and 0.5 ka.