Matías E. Medina

Synergistic roles of climate warming and human occupation in Patagonian megafaunal extinctions during the Last Deglaciation

Patagonian megafaunal extinctions reveal synergistic roles of climate change and human impacts. The causes of Late Pleistocene megafaunal extinctions (60,000 to 11,650 years ago, hereafter 60 to 11.65 ka) remain contentious, with major phases coinciding with both human arrival and climate change around the world. The Americas provide a unique opportunity to disentangle these factors as human colonization took place over a narrow time frame (~15 to 14.6 ka) but during contrasting temperature trends across each continent. Unfortunately, limited data sets in South America have so far precluded detailed comparison. We analyze genetic and radiocarbon data from 89 and 71 Patagonian megafaunal bones, respectively, more than doubling the high-quality Pleistocene megafaunal radiocarbon data sets from the region. We identify a narrow megafaunal extinction phase 12,280 ± 110 years ago, some 1 to 3 thousand years after initial human presence in the area. Although humans arrived immediately prior to a cold phase, the Antarctic Cold Reversal stadial, megafaunal extinctions did not occur until the stadial finished and the subsequent warming phase commenced some 1 to 3 thousand years later. The increased resolution provided by the Patagonian material reveals that the sequence of climate and extinction events in North and South America were temporally inverted, but in both cases, megafaunal extinctions did not occur until human presence and climate warming coincided. Overall, metapopulation processes involving subpopulation connectivity on a continental scale appear to have been critical for megafaunal species survival of both climate change and human impacts.

CONSUMO ANTROPICO DE PEQUEÑOS MAMIFEROS EN EL HOLOCENO DE ARGENTINA CENTRAL: PERSPECTIVAS DESDE EL ABRIGO ROCOSO QUEBRADA DEL REAL 1 (PAMPA DE ACHALA, CORDOBA)

Se estudiaron los restos de micromamiferos y otros pequenos vertebrados (Numero de Especimenes Identificados = 2,754) del sitio arqueologico Quebrada del Real 1, provincia de Cordoba, Argentina. Las muestras analizadas estuvieron domi nadas por roedores caviomorfos de las familias Caviidae y Ctenomyidae, incluyendo taxones de tamano relativamente grande (200‐700 g), habitos coloniales o gregarios, ubicacion predecible, y faciles de explotar como recurso. El estudio tafono mico de los restos sugiere que las acumulaciones tienen un origen mayoritario en actividades antropicas de consumo. Las evidencias incluyen la presencia de huellas de corte (especialmente en mandibulas y huesos del esqueleto apendicular) y un patron diferencial de alteracion termica, mayormente restringido a las porciones distales de tibias. En el contexto regio nal, el consumo de pequenos vertebrados sugiere que la implementacion de una dieta de amplio espectro posiblemente no sea un proceso arqueologico exclusivamente tardio, sino que se remonta al menos al limite Holoceno Medio-Tardio (ca. 3000 a.P.). We studied a large accumulation of micromammals and other small vertebrates (Number of Identified Specimens = 2,754) from the archeological site Quebrada del Real 1, Cordoba Province, Argentina. The samples were dominated by caviomorph rodents of the families Caviidae and Ctenomyidae. These taxa are relatively large (200‐700 g), with colonial or gregarious habits, predictable location, and easy to exploit as a resource. The taphonomic research suggests that this accumulation was largely made by human activities related to the consumption of these animals. The evidence includes the presence of cut marks, especially in mandibles and limb bones, and a differential pattern of thermal alteration mostly restricted to the distal portions of tibiae. In a regional view, the evidence suggests that the implementation of a broad spectrum diet is perhaps not exclusively a Late Holocene process but extended at least to the Middle-Late Holocene boundary (ca. 3000 years BP).

First records of Chenopodium spp./Amaranthus spp. starch grains and their relevance to the study of the late Holocene human subsistence in Central Argentina

The first Sierras of Córdoba (Argentina) evidences of Chenopodium spp. and/or Amaranthus spp. human consumption were presented in this paper. The identifications were made over micro-botanical remains – starch granules – from grinding tools and pottery from two archaeological sites: Quebrada del Real 1 (c. 3000 BP) and C.Pun.39 (c. 1000–500 BP). Multiproxy data suggest the management of high-nutritional wild plants and the early knowledge of the post-harvest processing technology required to remove the non-edible portion of seed. Thus, the presence of Chenopodium spp. was significant to the study of the subsistence strategies and the small-scale farming spread among the early late Holocene human societies in central Argentina, being especially pertinent as a potential comparison to seek the early phases of food transition in contemporary Andean South America, Mesoamerica, and Eastern North America.

INTENSIFICACIÓN Y DINÁMICA OCUPACIONAL EN EL PERÍODO PREHISPÁNICO TARDÍO DE LAS SIERRAS DE CÓRDOBA (ARGENTINA): UNA APROXIMACIÓN DESDE EL REGISTRO ARTEFACTUAL ÓSEO

Se presenta el analisis del conjunto artefactual oseo de cuatro sitios arqueologicos correspondientes al periodo Prehispanico Tardio de las Sierras de Cordoba (ca. 1.100-360 anos a.p., Argentina). El estudio tuvo como objetivo clasificar los artefactos en grupos morfologicos y determinar las actividades realizadas en los sitios. Los resultados indican la existencia de una tecnologia osea que utilizaba materiales disponibles localmente y se vinculaba con las necesidades de consumo de los grupos domesticos. Tambien sugieren que la adopcion de estrategias agricolas, ca. 1.100 anos a.p., fue acompanada por una intensificacion de las practicas de caza-recoleccion, con el desarrollo de nuevas tecnologias para la caza y el procesamiento de sus subproductos. Por ultimo, se concluye que los asentamientos interpretados como bases residenciales exhibieron una mayor diversidad de artefactos oseos y evidencias concretas de su manufactura, lo cual refleja la realizacion de una amplia gama de actividades y tiempos de permanencia extendidos.

Anthropogenic pollen, foraging, and crops during Sierras of Córdoba Late Prehispanic Period (Argentina)

The palynological study carried out in seven archaeological sites from Sierras of Córdoba Late Prehispanic Period (ca. 1500–360 yr BP) is presented in this article. The fossil pollen was used to assess the late prehispanic subsistence and mobility patterns based on their impact on local vegetation. Analogues obtained from modern vegetation and human-induced cultivation settings were used as a guideline for interpreting the ancient pollinic spectra. Results showed that anthropogenic pollen dominated by chenopod-amaranth plants occurred during a period of increased moisture and significant cultural change, where on-site farming and increasing occupation redundancy were identified. Thus, human disturbance and cultivation are thought to be the probable cause for elevated Chenopodiaceae–Amaranthaceae percentage in fossil assemblages. Consequently, the late prehispanic societies were likely modifying vegetation more extensively than had been previously assumed and the composition of ‘pristine’ landscape was not only altered by climate change or after the Europeans’ arrival. The ancient clearing of the forest for farming, housing, and/or other activities played a dynamic role in land cover conformation. So, the archaeological study of mixed foraging and cultivation economies needs to encompass human–plant–landscape interaction, leaving behind the concept of small-scale societies as passive foragers exploiting the ecosystem.

Bone tool and tuber processing: a multi-proxy approach at Boyo Paso 2, Argentina

This article provides results from a full morphological, use-wear and microfossil residue analysis of a notched bone tool made from a camelid scapula, which was recovered from the late pre-Hispanic site of Boyo Paso 2 (1500–750 years BP, Sierras of Córdoba, Argentina). The use-wear pattern showed striations similar to those recorded in experimental bone tools used for scraping activities. The starch grains found on the active or working edge are similar to the Andean tuber crop Oxalis tuberosa, and suggest that the tool was used for peeling wild or domesticated Oxalis sp. tubers, thereby questioning the disproportionate attention directed towards maize in late pre-Hispanic economies.