Climate change, availability of territory, and Late Pleistocene human exploration of Ultima Esperanza, South Chile
Introduction
The dispersal of humans throughout the world can be understood in terms of biogeographical corridors and barriers. The mapping and dating of critical resources and archaeological remains provides a history of human success and failure at different places in the planet (Gamble, 2013). Practically none of the regions successively incorporated by humans was immediately saturated with people, which is especially true in the more remote southern extremes of America where population was very low at the end of the Pleistocene (Borrero, 1999). In discussing the early evidence, we refer to Fuego-Patagonia, which is a geographical term introduced by Vaino Auer (1960) to treat Patagonia and Tierra del Fuego as a unit.
The earliest evidence for human presence in Fuego-Patagonia is concentrated in four southern regions, the central plateau in Santa Cruz (Miotti, 1998, Paunero, 2000), the Pali Aike Lava Field (Bird, 1988), Tierra del Fuego (Massone, 2004) and Ultima Esperanza (Nami, 1987, Prieto, 1991, Martin et al., 2004) (Fig. 1). These early occupations display similar sets of tools, hearths, and faunal remains. An important bias is that all the early archaeological sites are recorded from caves. Efforts to localize open-air sites relevant for the early peopling of the region are just beginning (Massone, 2004, Martin and San Román, 2010, Prieto and Labarca, 2011), but it is clear that they will be required to have a fuller view of early human settlement and activities.
At least two of the mentioned regions, the central plateau and Pali Aike, display evidence of relatively intense occupations, and thus can be considered population nodes or staging areas (sensu Anderson and Gillam, 2001) during the early process of colonization. It is our hypothesis that these are places with long-term occupations from which other regions were peopled. The evidence recovered at Ultima Esperanza and Tierra del Fuego is quantitatively less abundant. In this paper, we will discuss the first exploration of Ultima Esperanza, Chile, reviewing the available archaeological, paleontological and paleoecological evidence on the existence and access of land suitable for human installation. The central plateau and Pali Aike will be discussed and a general comparison with the case of Tierra del Fuego will be made.
Section snippets
Ultima Esperanza
The information for Ultima Esperanza is concentrated at the Cerro Benitez-Lago Sofía area (CBLS), and is limited to two sites. Cueva del Medio (CM) and Cueva Lago Sofía 1 (CLS1) (Nami, 1987, Nami, 1989-1990, Prieto, 1991, Jackson and Prieto, 2005, Martin et al., 2014) (Fig. 2). The tool assemblages recovered at these sites share a bifacial lithic technology with the rest of the oldest sites in Fuego-Patagonia (Nami, 2003). A bone technology is also well represented at these sites (Jackson, 1990
Paleoclimate and paleoecology
The geography of Fuego-Patagonia at the end of the Pleistocene was very different from today. The most important differences are related with Tierra del Fuego which at that time was part of the continent. It was during the early Holocene that it was cut off by the rising sea, and that the formation of the Strait of Magellan took place (McCulloch et al., 1997).
The continental ice cap also was a formidable barrier separating the eastern Patagonian steppes from the southern Pacific coasts, a
Exploration
Exploration refers to the initial radiation of humans into empty land (Borrero, 1994–1995), a process in which less resistance routes are usually used and most of the settling-in places are located at areas that are rich in resources. The main theories about the colonization of Fuego-Patagonia suggest that people was slowly moving south through the eastern steppes or near the Atlantic coast, today partially submerged (Borrero, 1999, Dillehay, 2000, Miotti, 2010), although a dispersion along the
Habitats, routes and corridors
The location of Ultima Esperanza differs significantly from that of other western Patagonian basins which constitute biogeographic dead-ends bounded by the continental ice-cap. Effectively, the Andean ice-cap was the western limit for the expansion of human populations and other species across hundreds of km between 45° and 52° S. Ultima Esperanza was certainly covered by ice at the end of the Pleistocene, but it was free of ice before human arrival to southern Patagonia. Perhaps for that
Discussion
Long-term occupations are expected at the highest ranked patches of any region (Bird and O'Connell, 2006). The central plateau is characterized by heterogeneous but abundant availability of high quality lithic sources (Cattáneo, 2006, Hermo, 2009) and adequate biotic resources and rockshelters (Miotti, 1998). Pali Aike is a place where rock sources are not as widespread and good quality as in the central plateau but are still abundant (Charlin, 2009). The availability of rockshelters, on the
Conclusions
Summing up, connections between the inhabitants of Pali Aike and Tierra del Fuego probably existed, but they were indirect and relatively old. There is no record of human presence in the north of Tierra del Fuego after the early occupation recorded at Tres Arroyos 1 until the middle of the Holocene. Starting ca. 8000 BP the terrestrial connection with the continent was definitely interrupted with the formation of the Strait of Magellan.
On the other hand, there is high connectivity between Pali
Acknowledgements
We thank the organizers of the Symposium, the Corporación Nacional Forestal (CONAF), the guards of Monumento Natural Cueva del Milodón, Hugo G. Nami, and Cecilia Pallo. The work presented here was funded by Projects FONDECYT 1150845 and CD MAG0901 (Universidad de Magallanes). Comments made by the reviewers were extremely helpful in preparing the final version of this paper.
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