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In vascular plants, larger seeds are generally associated with higher germination potential, healthier seedlings and overall higher rates of survivorship. How this relationship holds or what other physiological tradeoffs evolved in plants adapted to high-altitude environments, such as the tropical and subtropical highland Polylepis tree, remain unclear. In this study, we evaluated the relationship between seed mass and seedling performance by testing the reserve effect, the metabolic effect, and the seedling-size effect hypotheses in Polylepis tomentella Weddell (Rosaceae). Since the relationship between fitness and seed size can often depend on maternal plant size, we additionally investigated the association between germination success, seedling performance (survival, relative growth rate (RGR) and height), and size of bearing-seed trees under controlled greenhouse conditions. Our results showed that heavier seeds are more likely to germinate, but we did not find evidence that could support the reserve effect, metabolic effect or seedling-size effect. As seedlings from larger and medium seeds exhibited comparatively similar RGR, survival percentages and final size, maternal plant size was positively associated with improved seed quality and seedling performance. These results demonstrate that seed mass and maternal size during early seedling establishment are critical for Polylepis persistence, demography and conservation.

En este trabajo se describen las relaciones que las sociedades humanas establecieron con su entorno durante el período Formativo (3000-1000 aP) en la Pampa del Tamarugal, Desierto de Atacama, desde una perspectiva teórico-metodológica que pone el acento en el potencial del registro ecofactual. Éste, al mediar entre lo cultural y lo ambiental, proporciona información vital para una mejor comprensión de la relación entre naturaleza y cultura construida por estas sociedades. Queremos demostrar que este proceso forma parte de una larga historia de racionalización del desierto y de sus recursos silvestres, locales e introducidos, así como de la vivencia particular que tuvieron estas comunidades andinas. Por consiguiente, proponemos que la intervención humana en la Pampa del Tamarugal puede ser entendida como un cambio no sólo ecológico y económico, sino también cosmológico.

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.

Ritual practices and their associated material paraphernalia played a key role in extending the reach and ideological impact of early states. The discovery of a leather bag containing snuffing tablets and traces of psychoactive substances at Cueva del Chileno in the southern Andes testifies to the adoption of Tiwanaku practices by emergent local elites. Tiwanaku control spread over the whole of the south-central Andes during the Middle Horizon (AD 500–1100) but by the end of the period it had begun to fragment into a series of smaller polities. The bag had been buried by an emergent local elite who chose at this time to relinquish the former Tiwanaku ritual practices that its contents represent.

The domestication of llamas and alpacas was fundamental for the cultural and economic development of Andean societies, but the origins of camelid pastoralism as a distinct mode of socioeconomic organization remain little understood. Whereas most archaeological interpretations of prehispanic highland societies emphasize the transition from hunting-gathering to agriculture as a process marked by the establishment of agricultural sedentary villages, other subsistence and mobility strategies have been for the most part overlooked. A case in point is the Wankarani cultural complex from the Central Altiplano of Bolivia, which has been interpreted as an example of an early village-based sedentary society. Here, I argue that a model of mobile pastoralism based on ethnoarchaeological research better explains the Central Altiplano's Formative period archaeological record. Recently collected data support this proposition. Settlement patterns consisted of multiple dispersed camps attached to residential bases occupied recurrently. Horizontal excavations from a residential base revealed structures and features analogous to pastoralist landscapes documented around the world. Faunal identification confirmed the preponderance of domesticated camelids. Based on this evidence, I argue that we need better explanatory frameworks for approaching the origins, organization, and variability associated with early food producing societies such as mobile camelid pastoralists.