Because the 14C calibration curves IntCal and SHCal are based on data from temperate latitudes, it remains unclear which curve is more suitable for archaeological and paleoenvironmental records from tropical South America. A review of climate dynamics reveals a significant influx of Northern Hemisphere air masses and moisture over a substantial part of the continent during the South American Summer Monsoon (SASM). Areas affected by the SASM receive unknown amounts of input from both hemispheres, where an argument could be made for either curve. Until localized tree-ring data can resolve this, we suggest using a mixed calibration curve, which accounts for inputs from both hemispheres, as a third calibration option. We present a calibration example from a crucial period of environmental and cultural change in the southern Lake Titicaca. Given our current lack of data on past ∆14C variation in South America, our calibrations and chronologies will likely change in the future. We hope this paper spurs new research into this topic and encourages researchers to make an informed and explicit choice of which curve to use, which is particularly relevant in research on past human–environmental relationships.

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A multidecadal-scale lake-level reconstruction for Lago Wiñaymarca, the southern basin of Lake Titicaca, has been generated from diatom species abundance data. These data suggest that ~6500 cal yr BP Lago Wiñaymarca was dry, as indicated by a sediment unconformity. At ~4400 cal yr BP, the basin began to fill, as indicated by the dominance of shallow epiphytic species. It remained somewhat saline with extensive wetlands and abundant aquatic plants until ~3800 cal yr BP, when epiphytic species were replaced by planktic saline-indifferent species, suggesting a saline shallow lake. Wiñaymarca remained a relatively shallow lake that fluctuated on a multidecadal scale until ~1250 cal yr BP, when freshwater planktic species increased, suggesting a rise in lake level with a concomitant decrease in salinity. The lake became gradually fresher, dominated by deep, freshwater species from ~850 cal yr BP. By ~80 cal yr BP, saline-tolerant species were rare, and the lake was dominated by freshwater planktic diatoms, resembling the fresh and deep lake of today. These results reveal a more dynamic and chronologically specific record of lake-level fluctuations and associated ecological conditions that provide important new data for paleoclimatologists and archaeologists, to better understand human-environmental dynamics during the mid- to late Holocene.

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In the Lake Titicaca Basin of the Andes, narratives of agricultural change have focused exclusively on a single innovation: raised fields. In this article, I examine macrobotanical remains and other archaeological datasets to elucidate a wider range of past farming practices that contributed to processes of agricultural change on the Taraco Peninsula, Bolivia, during the Formative Period (1500 B.C.E.-C.E. 500). This analysis reveals strong continuities in crop selection through time, with farmers gradually diversifying a basic set of cultigens-quinoa and tubers-but never abandoning them. Patterns in wild plant species indicate continuity in agropastoral land use up to the Late Formative Period (second century C.E.) when the unintended consequences of long-term tilling and camelid grazing transformed the botanical landscape into one that required a new set of practices to remove weeds and replenish nutrients to the soils. Examining how these practices and the farmers enacting them articulated with broader processes of demographic, environmental, and sociopolitical change reveals dynamic, multivariate courses of agricultural change even before the inclusion of raised fields. [agricultural practices, ethnobotany, archaeobotany, Lake Titicaca Basin, Andes]RESUMEN En la cuenca del lago Titicaca de los Andes, las narrativas del cambio agrícola se han enfocado exclusivamente en una sola innovación: los campos elevados. En este artículo, se analizan restos macrobotánicos y otros datos arqueológicos para investigar un rango más amplio de prácticas agrícolas que contribuyeron a los procesos de cambio en la península de Taraco, Bolivia a lo largo del período Formativo (1500 a.C. -500 d.C.). Este análisis revela fuertes continuidades en la selección de cultivos a través del tiempo con la diversificación gradual del conjunto básico de quinua y tubérculos. Los patrones de las especies de plantas silvestres indican una continuidad en el uso agro-pastoral del paisaje hasta el período Formativo Tardío (segundo siglo d.C.) cuando las consecuencias no intencionadas de las precedentes actividades agrícolas y pastoriles de camélidos transformaron el paisaje botánico en uno que requería de un nuevo conjunto de prácticas agrícolas para eliminar las malezas y renovar los nutrientes de los suelos. Evaluar cómo estas prácticas y los agricultores que las llevaron adelante se articularon con procesos de cambio demográficos, medioambientales y socio-políticos revela trayectorias multivariadas y dinámicas de cambios agrícolas que antecedieron a la incorporación de campos elevados. [prácticas agricolas, etnobotánica, arqueobotánica, cuenca de Lago Titicaca, Andes] A nthropologists have a long tradition of studying societies through the ways in which they obtain their food. The expansion and intensification of agriculture and its role in the development of complex societies has been a central