Calogero M. Santoro

Ancient mitochondrial DNA provides high-resolution time scale of the peopling of the Americas.

Native American population history is reexamined using a large data set of pre-Columbian mitochondrial genomes. The exact timing, route, and process of the initial peopling of the Americas remains uncertain despite much research. Archaeological evidence indicates the presence of humans as far as southern Chile by 14.6 thousand years ago (ka), shortly after the Pleistocene ice sheets blocking access from eastern Beringia began to retreat. Genetic estimates of the timing and route of entry have been constrained by the lack of suitable calibration points and low genetic diversity of Native Americans. We sequenced 92 whole mitochondrial genomes from pre-Columbian South American skeletons dating from 8.6 to 0.5 ka, allowing a detailed, temporally calibrated reconstruction of the peopling of the Americas in a Bayesian coalescent analysis. The data suggest that a small population entered the Americas via a coastal route around 16.0 ka, following previous isolation in eastern Beringia for ~2.4 to 9 thousand years after separation from eastern Siberian populations. Following a rapid movement throughout the Americas, limited gene flow in South America resulted in a marked phylogeographic structure of populations, which persisted through time. All of the ancient mitochondrial lineages detected in this study were absent from modern data sets, suggesting a high extinction rate. To investigate this further, we applied a novel principal components multiple logistic regression test to Bayesian serial coalescent simulations. The analysis supported a scenario in which European colonization caused a substantial loss of pre-Columbian lineages.

Emergence of social complexity among coastal hunter-gatherers in the Atacama Desert of northern Chile

The emergence of complex cultural practices in simple hunter-gatherer groups poses interesting questions on what drives social complexity and what causes the emergence and disappearance of cultural innovations. Here we analyze the conditions that underlie the emergence of artificial mummification in the Chinchorro culture in the coastal Atacama Desert in northern Chile and southern Peru. We provide empirical and theoretical evidence that artificial mummification appeared during a period of increased coastal freshwater availability and marine productivity, which caused an increase in human population size and accelerated the emergence of cultural innovations, as predicted by recent models of cultural and technological evolution. Under a scenario of increasing population size and extreme aridity (with little or no decomposition of corpses) a simple demographic model shows that dead individuals may have become a significant part of the landscape, creating the conditions for the manipulation of the dead that led to the emergence of complex mortuary practices.

External auditory exostosis in prehistoric Chilean populations: a test of the cold water hypothesis.

Over one thousand prehistoric crania (n = 1,149) from northern Chile were analyzed to determine if the presence of external auditory exostosis (EAE) was a type of subsistence-induced pathology, a consequence of habitual fishing in the cold water of the Pacific Ocean, rather than genetically determined. To test this occupational hypothesis, the sample was divided according to chronology, type of economy, site elevation, and sex. The crania came from 43 sites, including the coast, lowland valleys (100-2,000 m), and highlands (2,000 to 4,000 m) with a time frame of 7,000 B.C. to the Inca era (1500 A.D.). There was a significant association between EAE, environment, and sex. The coastal inhabitants had the highest prevalence of EAE with 30.7% (103/336), followed by 2.3% (6/24) for the valley people and 0% (0/549) for highlanders. Coastal and valley men were significantly more affected than their female counterparts. Contrary to expectations, there was no significant association between EAE and economy and/or chronology. In the Arica area, the early Chinchorro fishers, without agriculture, had 27.7% (26/94) EAE, the subsequent agro-pastoralists, 42.7% (32/75), and the late Arican agro-pastoral fishers had 35.6% (36/101) EAE. Apparently, with the advent of agriculture, the coastal Arican populations increased their ocean harvests, rather than decreased them, to gain a surplus in order to trade with nonmaritime groups.

THE IMPACT OF ENSO IN THE ATACAMA DESERT AND AUSTRALIAN ARID ZONE: EXPLORATORY TIME-SERIES ANALYSIS OF ARCHAEOLOGICAL RECORDS

La comparacion de datos arqueologicos del desierto de Atacama y de la zona arida de Australia muestra el impacto de El Nino-Oscilacion del Sur en los ultimos 5.000 anos. Con base en un listado de > 1.400 dataciones radiocarbonicas de ambas regiones, utilizadas como fuente indirecta de fluctuaciones de la poblacion, se realizaron graficos de densidad de las dataciones para explorar las respuestas de las poblaciones prehistoricas a las variaciones climaticas provocadas por ENSO. Bajo un regimen ENSO las precipitaciones se encuentran en antefase entre Australia y la costa del norte de Chile. Dado que ENSO impacta en la productividad de los recursos marinos y suprime el ingreso de humedad de la cuenca del Amazonas, su efecto en las economias de subsistencia de ambos lados del Pacifico Tropical deberia correlacionarse positivamente. Esto se confirma a traves de analisis cruzados de espectros de graficos de densidad de radiocarbonos, lo que muestra fluctuaciones sincronicas de la poblacion en ambos lados del Pacifico Tropical (r = > 0,82). Las bases de datos de Australia y del desierto de Atacama muestran un aumento gradual de la poblacion desde los 13 mil cal anos a.p., y un incremento importante durante el optimo climatico del Holoceno medio. La intensificacion de ENSO a partir de los 3,7 cal anos a.p. se correlaciona con ciclos de florecimiento y declinacion de la ocupacion humana en ambos lados del Pacifico, incluyendo el colapso del sistema economico y cultural en la costa del desierto de Atacama alrededor de 3 mil anos cal a.p. y la declinacion de la poblacion en las zonas interiores aridas del Atacama y del centro de Australia, entre 3-2 mil anos cal a.p. Posterior a 2 mil anos cal a.p. las respuestas adaptativas varian entre ambas regiones, aunque se produce una recuperacion general de las poblaciones en sus zonas aridas interiores.

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...

Inca expansion and parasitism in the Lluta Valley: preliminary data

Assessing the impact of cultural change on parasitism has been a central goal in archaeoparasitology. The influence of civilization and the development of empires on parasitism has not been evaluated. Presented here is a preliminary analysis of the change in human parasitism associated with the Inca conquest of the Lluta Valley in Northern Chile. Changes in parasite prevalence are described. It can be seen that the change in life imposed on the inhabitants of the Lluta Valley by the Incas caused an increase in parasitism.

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”).

Análisis de Adn Mitocondrial en Momias del Norte de Chile avala Hipótesis de Orígen Amazónico de Poblaciones Andinas

La hipotesis del origen amazonico de las poblaciones andinas basada en el analisis de marcadores geneticos nucleares es contrastada haciendo uso de ADN mitocondrial antiguo aislado de restos esqueletales de poblaciones prehistoricas del Valle de Azapa, Arica, Chile. Se analizaron 42 muestras de las cuales 32 rindieron amplificados para los cuatro marcadores amerindios permitiendo su tipificacion. La distribucion de haplogrupos (A: 31,2 %, B: 21,9 %, C: 31,2 %, D: 3,1 % y otros 12,5 %) relaciona geneticamente a las poblaciones estudiadas con grupos amazonicos y andinos actuales. El numero de muestras analizadas no permite aun una subdivision por fases cronologicas con el objeto de poner a prueba las hipotesis planteadas por arqueologos y bioantropologos para explicar la microevolucion biocultural de las poblaciones estudiadas

OCUPACIÓN HUMANA PLEISTOCÉNICA EN EL DESIERTO DE ATACAMA: PRIMEROS RESULTADOS DE LA APLICACIÓN DE UN MODELO PREDICTIVO DE INVESTIGACIÓN INTERDISCIPLINARIA

Sudamerica cuenta con evidencias de ocupacion humana desde los 14.600 anos calibrados a.p. (14,6 ka). Sin embargo, en el desierto de Atacama existe una notoria ausencia de ocupaciones pre-11,5 ka entre las latitudes 17° a 21° S (Atacama Norte). Esto debido, en parte, a que se ha desestimado como territorio atractivo para poblaciones de la transicion Pleistoceno-Holoceno, dadas sus condiciones actuales de extrema aridez. Sobre la base de ciertos datos paleoecologicos generales, que sugerian condiciones de mayor disponibilidad de agua en la vertiente occidental de los Andes desde los 17 a 9,5 ka, se realizaron busquedas sistematicas de paleomadrigueras de roedores y paleohumedales en ambientes de precordillera y quebradas (1.000 a 3.000 msm). Esto permitio identificar habitat especificos que presentaran condiciones favorables para el asentamiento humano temprano y de esta manera buscar sitios arqueologicos en forma dirigida. El modelo metodologico interdisciplinario de caracter predictivo, que se resume en este articulo, permitio identificar un conjunto de sitios entre los que destaca Quebrada Mani 12, donde se constataron las primeras evidencias de ocupaciones pleistocenicas tardias (~11,9 a 12,7 ka) en el desierto de Atacama Norte.

Craniofacial chronological microdifferentiation of human prehistoric populations of the Azapa valley, northern Chile

Los desarrollos culturales ocurridos en el altiplano en el area circumtiticaca en los Andes centrales, ejercieron influencia sobre las elaboraciones culturales de los grupos humanos que poblaban el Valle de Azapa cercano a la ciudad de Arica y la costa del norte de Chile. En esta comunicacion presentamos un analisis de distancias que demostro que una diferenciacion craniofacial acompano en el valle el proceso de evolucion cultural. La influencia biologica de Tiwanaku se refleja parcialmente en la morfologia craniofacial, proporcionando evidencia preliminar de que los cambios culturales en el valle se realizaron acompanados de flujo genico intermitente desde el altiplano, especialmente durante las fases Alto Ramirez y San Miguel