Lautaro Núñez

A 22,000 14C year BP sediment and pollen record of climate change from Laguna Miscanti (23°S), northern Chile

Lake sediments and pollen, spores and algae from the high-elevation endorheic Laguna Miscanti (22°45′S, 67°45′W, 4140 m a.s.l., 13.5 km2 water surface, 10 m deep) in the Atacama Desert of northern Chile provide information about abrupt and high amplitude changes in effective moisture. Although the lack of terrestrial organic macrofossils and the presence of a significant 14C reservoir effect make radiocarbon dating of lake sediments very difficult, we propose the following palaeoenvironmental history. An initial shallow freshwater lake (ca. 22,000 14C years BP) disappeared during the extremely dry conditions of the Last Glacial Maximum (LGM; 18,000 14C years BP). That section is devoid of pollen. The late-glacial lake transgression started around 12,000 14C years BP, peaked in two phases between ca. 11,000 and <9000 14C years BP, and terminated around 8000 14C years BP. Effective moisture increased more than three times compared to modern conditions (∼200 mm precipitation), and a relatively dense terrestrial vegetation was established. Very shallow hypersaline lacustrine conditions prevailed during the mid-Holocene until ca. 3600 14C years BP. However, numerous drying and wetting cycles suggest frequent changes in moisture, maybe even individual storms during the mid-Holocene. After several humid spells, modern conditions were reached at ca. 3000 14C years BP. Comparison between limnogeological data and pollen of terrestrial plants suggest century-scale response lags. Relatively constant concentrations of long-distance transported pollen from lowlands east of the Andes suggest similar atmospheric circulation patterns (mainly tropical summer rainfall) throughout the entire period of time. These findings compare favorably with other regional paleoenvironmental data.

From proxy data to paleoclimate interpretation: the mid-Holocene paradox of the Atacama Desert, northern Chile

Abstract The question whether the mid-Holocene climate (between ca. 9 and 4 cal kyr B.P.) in the Atacama Desert and the Central Andes in general was humid or dry has wide implications with regard to the understanding of long-term climate variability in South America. Paleosols, regional groundwater tables, abiotic proxy data and pollen of aquatic plants in lake sediments show a marked and rapid shift from very humid late-glacial/early Holocene climatic conditions (between ca. 14 and 9.5 kyr B.P.) to extremely dry mid-Holocene conditions (more arid than today between ca. 9 and 4 kyr B.P.). An exception during this hyperarid period is a century-scale more humid interval around ca. 5.5–6 kyr B.P. that appears systematically in lake sediment archives. In contrast, pollen for most terrestrial plants preserved in lake sediments do not show major changes during the Holocene, whereas more humid mid-Holocene conditions (compared with late Holocene conditions) were inferred from plant macrofossils in rodent middens. Is the reason for this disagreement to be attributed to misinterpretation of the paleoenvironments or of the proxy records themselves, or to incomplete paleoclimatic interpretation of the paleoenvironments? We argue that these different paleoclimate archives record different aspects and facets of ‘climate’. While paleosols and groundwater in the Atacama Desert record low-frequency climate variability at century to millennium scales, lake sediments on the Altiplano record decade- to century-scale variability. Terrestrial vegetation responds to shorter high-frequency climate variability at seasonal to inter-annual scales and preferably to humid years. Vegetation remains in ‘hibernation’ or does not germinate during arid years. Thus information from these three types of archives is not a priori comparable and requires careful site-specific, archive-specific and time-scale-specific evaluation. What is natural in modern climatology is also true for paleoclimatology: a comprehensive assessment must account for the complex daily and seasonal cycles, for the range of climate variability and trends at different scales in space and time, for impacts of short-term extreme events, and for specific, often non-linear responses of individual bio-geo-physical archives to any of the numerous aspects of ‘climate’.

EL TRÁNSITO ARCAICO-FORMATIVO EN LA CIRCUMPUNA Y VALLES OCCIDENTALES DEL CENTRO SUR ANDINO: HACIA LOS CAMBIOS "NEOLÍTICOS"

Resumen es: Se sintetizan los procesos socioculturales y productivos de las ocupaciones arcaicas costenas y andinas de la circumpuna y valles occidentales, area Cent...

Mid-Holocene climate and culture change in the South Central Andes

This chapter reviews the history of study and the current status of Mid-Holocene climatic and cultural change in the South Central Andes, which host a wide range of different habitats from Pacific coastal areas up to extremely harsh cold and dry environments of the high mountain plateau, the altiplano or the puna. Paleoenvironmental information reveals high amplitude and rapid changes in effective moisture during the Holocene period and, consequently, dramatically changing environmental conditions. Therefore, this area is suitable to study the response of hunting and gathering societies to environmental changes, because the smallest variations in the climatic conditions have large impacts on resources and the living space of humans. This chapter analyzes environmental and paleoclimatic information from lake sediments, ice cores, pollen profiles, and geomorphic processes and relates these with the cultural and geographic settlement patterns of human occupation in the different habitats in the area of southern Peru, southwest Bolivia, northwest Argentina, and north Chile and puts in perspective of the early and late Holocene to present a representative range of environmental and cultural changes. It has been found that the largest changes took place around 9000 cal yr BP when the humid early Holocene conditions were replaced by extremely arid but highly variable climatic conditions. These resulted in a marked decrease of human occupation, “ecological refuges,” increased mobility, and an orientation toward habitats with relatively stable resources (such as the coast, the puna seca, and “ecological refuges”).

GEOGLIFOS Y TRÁFICO PREHISPÁNICO DE CARAVANAS DE LLAMAS EN EL DESIERTO DE ATACAMA (NORTE DE CHILE)

Este estudio aporta nuevos antecedentes empiricos, resultado de las excavaciones de cuatro campamentos de uso transitorio y dos entierros humanos, asociados a sitios con geoglifos, ubicados a lo largo de una ruta caravanera prehispanica de 150 km, que conecto a los oasis de Pica con la costa del oceano Pacifico. Puesto que la mayoria de estos sitios se encuentra en territorios deserticos sin recursos, asociados a contextos tales como coprolitos de llamas y hojas de maices, argumentamos que fueron componentes directos del trafico caravanero. Esta ruta estuvo vinculada al intenso trafico macrorregional de larga distancia po r donde circulaban bienes economicos y suntuarios procedentes de los mas diversos ambientes (selva-altiplano-oasis-pampacosta). Las seis dataciones de radiocarbono, obtenidas de los contextos excavados, indicarian que, si bien la mayoria de los geoglifos de la transecta de estudio fueron elaborados durante el periodo del Desarrollo Regional (900-1.450 anos d.C.), cierta s rutas transdeserticas ya estaban en uso, al menos desde el Arcaico Tardio (1.300 anos a.C.), por parte de cazadores, pescadores y recolectores. Palabras claves: geoglifos, caravanas de llamas, rutas de trafico prehistorico, campamentos transitorios, dataciones absolutas. This study brings new empirical evidence, resulting from the excavation of four transitory camp sites and two human burials associated with geoglyphs, and found along a prehispanic caravan path of 150 km long, connecting the Pica oasis with the Pacific coastal ocean in the Atacama desert in northern Chile. Since the majority of these sites are found in resourceless desertic areas and are associated to contexts such as llama coprolites and corn leaves, we argue that these sites were direct components of caravan trafficking. This route was linked to an intensive long distance macro-regional traffic associated with the circulations of economic and sumptuary goods from diverse origins, including the selva, altiplano, oasis, pampa and coast. Radiocarbon dates obtained at the excavations indicate that even though most of the geoglyphs were created during the Desarrollo Regional period (900-1,450 yrs. A.D.) some transdesertic routes were already used, from at least the Late Archaic Period (1,300 B.C.) by hunters, fishers and gatherers.

Human Dimensions of Late Pleistocene/Holocene Arid Events in Southern South America

Publisher Summary This chapter discusses human dimensions of late Pleistocene/Holocene arid events in southern South America, where, examples from late glacial, and early and mid-Holocene archaeological sites in southern South America provide information about the human dimensions of past climate changes. Particularly in semiarid areas with marginal food, and water resources, changes from humid to arid conditions coincided with major changes in human occupational, and cultural patterns. The end of the first period of human occupation in central Chile coincided with rapidly increasing aridity, when trees were replaced by shrubs and herbs, the Pleistocene paleolakes disappeared, and the Pleistocene megafauna became extinct. The Paleo-Indian hunters occupied ecological refuges around lakes, where the resources were concentrated in an environment under general water stress. A similar process was observed 2000 years later in the Atacama Desert, and Altiplano of northern Chile, when the first period of human occupation came to an abrupt end, synchronously with the rapid desiccation of early Holocene paleolakes, and the disappearance of abundant water, vegetation, and animal resources. The subsequent extremely arid mid-Holocene environments resulted in a general hiatus of human occupation in the Atacama basin, whereas widespread resettlement coincided again with a rise of the paleolake levels to the modern levels.

La naturaleza de la expansión aldeana durante el Formativo Tardío en la Cuenca de Atacama

La implantacion horticola de los oasis piemontanos de la cuenca del Salar de Atacama comenzo antes de los 700 anos a.C. de acuerdo al registro cronoestratigrafico de maiz durante la fase Tilocalar del Formativo Temprano (1.400 - 400 a.C.). Las practicas propiamente agricolas extensivas se habrian consolidado durante las fases posteriores al Formativo Temprano, esto es, desde los 400 a.C. a los 600 d.C. a traves de asentamientos complejos datados por C14 en los oasis piemontanos: Tulor-1 (380 a.C. - 200 d.C.) y Coyo-Aldea (660 - 995 d.C.). Se propone que para acceder a la produccion ganadera derivada de la fase Tilocalar, poco adaptable a los oasis calidos, durante el Formativo Tardio se controlaron las vegas del salar, quebradas intermedias y alta puna, a traves de un regimen trashumantico complementario, conducido esta vez desde la cabecera sociopolitica de los oasis de San Pedro de Atacama. El registro de siete asentamientos formativos tardios datados por C14 en los extremos perifericos de la cuenca de Atacama, asociados a quebradas estrechas esencialmente pastoralistas (Puripica y Tulan), dan cuenta de un proceso expansivo orientado a equilibrar la productividad agraria y pecuaria. En este sentido se propone que la ocupacion post Tilocalar del hinterland forrajero ocurrio a traves de la fundacion de aldeas que comparten similitudes arquitectonicas, artefactuales, ambientales y cronologicas, irradiadas desde el nucleo de San Pedro de Atacama

Cambios ambientales pleistoceno-holocénicos: ocupación humana y uso de recursos en la Puna de Atacama (norte de Chile)

Los datos paleoambientales indican que los recursos de agua, vegetacion y fauna de la Puna de Atacama (>4000 m.snm), fueron abundantes durante la ultima edad glacial y Holoceno Temprano, mientras que las condiciones de aridez prevalecieron bajo los 3500 m. Los cazadores del Periodo Arcaico Temprano (ca. 10800 a 8500 AP) estaban adaptados a la alta Puna y su piedemonte, a lo largo del desague de los rios provenientes de las tierras altas, en donde los recursos de diferentes alturas se explotaban optimamente en forma trashumante dentro de distancias cortas. Los lagos se restringieron a los niveles actuales y el proceso pedogenesico concluyo en la alta Puna. Los recursos naturales decrecieron significativamente durante el Periodo Arcaico Medio (ca. 8500-5000 AP), de manera que las actividades humanas se restringieron a sitios mas estables en terminos de recursos, entre los rios Loa y Puripica al norte de los 23°. Los habitats menos estables al sur de esta latitud (salares de Atacama y Punta Negra) fueron abandonados. Las relaciones entre puntuacion de recursos, densidad ocupacional y cambios climaticos pueden ser revisados a la luz de los ajustes de los patrones de circulacion subtropical, tal como se ha advertido con nuestro conjunto de datos provenientes de la Puna de Atacama.ABSTRACTPaleoenvironmental data from the Puna de Atacama (21°- 24° S) indicate that water, vegetation and animal resources were more abundant during late glacial and Early Holocene times than today. The rate of precipitation increased above 4000 m elevation to 400->500 mm/yr compared to the present 200 mm/yr. Dry conditions prevailed below 3500 m. The early archaic hunters (ca. 10800-8500 BP) inhabited the High Puna and its western slope, where water was available due to higher river runoff from the altiplano, and the resources in different elevation zones were accesible. Natural resources decreased significantly during the Middle Archaic Period (ca. 8500-5000 BP). Lakes receded to today’s levels, the pedogenesis in the Altiplano terminated, and human activities were restricted to the most stable sites in the rio Loa and the rio Puripica catchments north of 23° S. The less stable habitats south of 23° S (Salar de Atacama and Punta Negra) were abandoned. The climatic changes are best explained by shifts of the subtropical circulation.

SEQUENTIAL ANALYSIS OF HUMAN OCCUPATION PATTERNS AND RESOURCE USE IN THE ATACAMA DESERT

Se presenta una secuencia cronologica de las ocupaciones humanas del Desierto de Atacama y los distintos patrones de explotacion de recursos desde fines del Pleistoceno hasta la actualidad, en uno de los territorios mas esteriles del Nuevo Mundo. Esta secuencia ocupacional comprende un lapso temporal de 11.000 anos, en la cual se examinan las distintas modalidades del manejo de recursos naturales a traves de practicas de caza, pesca, recoleccion, domesticacion de animales, actividades agrarias, pecuarias, mineras, intercambio y comercio. Ademas, se incorporan las innovaciones basadas en la explotacion minera a escala industrial durante el periodo colonial e industrial del siglo XIX hasta la actualidad (megaproyectos extractivos). Se discuten las diversas respuestas culturales, tecnologicas y productivas en terminos de continuidad y cambio en las ocupaciones humanas y su impacto en la distribucion espacial de la poblacion en los diversos ambientes entre los Andes y el Pacifico. Se observa un acentuado desbalance entre la produccion de los recursos naturales tradicionales y las labores minero-extractivas, alcanzando un limite de alta fragilidad ecologica a traves de la utilizacion indiscriminada del recurso hidrico. La carencia de investigaciones y la falta de modelos alternativos ponen en peligro un desarrollo sustentable, en un marco de desencuentro entre discursos politicos, cientificos y eticos.

Biodiversity and Human Impact During the Last 11,000 Years in North-Central Chile

During the pre-Columbian period (11,000 14C years b.p.-1540 a.d.), the interaction between humans and their environment can be characterized as relatively harmonious with regard to the effects of resource exploitation patterns and subsistence practices in arid and semi-arid ecosystems of north-central Chile. The strong dependency on local resources stimulated a close coupling between environmental change and human population. However, since the 16th century, ecosystems in this area have been exposed to three trends that have dramatically disrupted a long-term relationship between human populations and natural resources. First, the appearance of European settlements focused on mining activities and created urban markets for agricultural products. Second, the establishment of European land-use patterns that, by focusing on economically important and highly productive plant and animal species, out-competed and displaced local native and less productive species to marginal areas and led to the widespread degradation of soils. Third, local indigenous populations retreated into “refuge areas” where they were able to maintain their traditional pattern of resource use which is based on self-subsistence and exchange of the surplus production.