Hakenasa Cave and Its Relevance for the Peopling of the Southern Andean Altiplano

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Introduction

The human colonisation of the earth's high plateaux took place towards the end of the Pleistocene in the Old World (Africa and Asia; Aldenderfer 2006, 2007), and during the Pleistocene-Holocene transition in the New World. The Andean Altiplano has been regarded as a marginal human habitat due to its low biological productivity, extreme temperature fluctuations and the negative biological effects of hypoxia (Aldenderfer 1998; Llanos et al. 2007). Yet today, it possesses considerable climate variability and cultural diversity, and its tropical region has witnessed the rise and fall of prominent civilisations (Binford et al. 1997).

The Altiplano of northern Chile, close to the southern border of the tropical belt, has lacked evidence of early human occupation, perhaps the consequence of unfavourable palaeoenviromental conditions, the conservation and visibility of the sites and/or the failure of the archaeological surveying tactics. Nevertheless, previous studies have not taken into account the palaeoecological variability or the complexities involved in the introduction and settling of human groups in previously uninhabited regions (Ingold 1987, 2000; Beaton 1991 ; Dixon 2001 ; Dillehay 2002; Kelly 2003; Steele & Rockman 2003; Jackson & Mendez 2004; Gaudin 2006; Santoro & Latorre 2009).

Here, we present a dated sequence including the earliest level of human occupation at Hakenasa, a cave located at 4100m asl in the Altiplano of northern Chile, in the Atacama Desert (17.5[degrees] S). The lithic technology allows us to propose that Hakenasa functioned as a logistical camp, considering its highly curated pattern, the occurrence of final stages of the lithic operational sequence and a medium frequency of lithic breakage (Binford 1979; Lemmonier 1991). A series of known, and new, radiocarbon and ANIS dates indicate that this high Andean area was settled by the end of the Pleistocene (c. 11 500 cal BP). This coincided with an improvement in the previous harsh glacial conditions which then became considerably more favourable for human habitation than today (Moreno et al. 2009).

Hakenasa: palaeoenvironment

Hakenasa Cave is located at 4100m asl in the high Andean steppe of northernmost Chile at 17[degrees] 50'S, 69[degrees] 22'W (Figure 1). Situated along the northern slope of the Ancopujo canyon that drains into the Cosapilla or Caquena River, the site is at the base of a low ignimbrite cliff. The cave overlooks a high altitude wetland or bofedal in which vicunas, rodents and birds abound (Figure 2). The associated plant communities are dominated by grasses and shrubs of the families Asteraceae and Solanaceae and are situated within the high Andean steppe (Villagran et al. 1999). The climate is arid and rainfall, from summer convective storms, rarely exceeds more than 300mm/yr. Daily thermal amplitude is high at 10-20[degrees] C.

Moreno et al. (2009) recently summarised some of the most important impacts of regional past climate change by comparing the major cultural discontinuities at Hakenasa to the limnogeological record of Lago Chungara (located 40km south). In turn, two ice-cores collected from the summit of Nevado Sajama (55km from Hakenasa) record major changes in [[delta].sup.8]O along with anion concentrations and dust accumulation over the last 25 000 years (Thompson et al. 1998, 2000). Both records, along with lake level data from the Uyuni basin (Placzek et al. 2006) indicate that the climate was wetter and possibly colder (see also Betancourt et al. 2000; Grosjean et al. 2001; Blard et al. 2009) between 17 500 and 14 000 cal BP: the Tauca lake cycle. This was followed by a regionally extensive, submillenial-scale drought that took place around 14 000 cal BP (Latorre et al. 2006; Placzek et al. 2006; Placzek et aL 2009). These records also reveal that high lake levels returned to Salar de Coipasa along with decreased [[delta]. …