Among the many spatially discrete resources that the Andes offer, obsidian is one of particular utility both for the ancient people and for archaeologists. Each source of obsidian has a unique chemical signature, so obsidian in archaeological sites can be traced back to its origin. Over the past twenty-five years, Richard Burger and his colleagues have identified the major types of Andean obsidian and located most of the sources (see Burger et al. 2000 for a review and demonstration of the anthropological utility of obsidian sourcing). Obsidian debitage from the Terminal Pleistocene component at Quebrada Jaguay is among the earliest samples studied, and all of the fragments came from the Alca source, some 165 km distant from this coastal fishing site at elevations of 2,800 to 3,800 masl and higher (Jennings and Glascock 2002; Sandweiss et al. 1998). Only 20 km further away along a better-watered route, the 4,900 masl Chivay obsidian source was extensively used later in prehistory, though no Chivay material was present at Que-brada Jaguay. Did this difference represent early territoriality or inaccessibility of the Chivay source? Preliminary fieldwork and dating of glacial features by glacial geologist Harold Borns (personal communication) and Daniel Sandweiss support the latter and suggest that a Younger Dryas age (ca.13,000-11,400 cal yr BP) glacial readvance as low as 4,650 masl would have covered the Chivay source during the Terminal Pleistocene occupation at Quebrada Jaguay.
Sea Level, Site Preservation, and Early Maritime Adaptations
Despite C. Barrington Brown’s (1926) early report of preceramic sites in far northern Peru, it was the work of Junius Bird (et al. 1985) at Huaca Prieta, northern Peru, in the late 1940s that put the Central Andean coastal preceramic on the map. Subsequent research on this epoch focused on the central Peruvian coast, and in the 1960s Edward Lanning (e. g., 1967) devised an influential cultural sequence for the coastal preceramic based on his work at Ancon-Chillon near Lima. Lanning did not find any significant use of marine resources until around 5800 cal yr BP, with his Encanto phase. At the same time, James B. Richardson III was beginning research on the preceramic of far northern Peru, where he found marine mollusks in Amotape phase campsites dating as early as 12,800 cal yr BP. Adding these data to other whispers of pre-5800 maritime adaptations, Richardson (1981) sought and found an explanation for the spatial distribution of such evidence: early fishing seemed to occur only where the continental shelf was narrow. As he pointed out, these are the sectors of ancient shorelines that suffered the least horizontal displacement as sea level rose with deglaciation from 21,000-5800 cal yr BP. Places like Ancon-Chillon have a relatively wide shelf, so the shoreline moved fairly quickly until sea level stabilization, drowning any early maritime sites that might have existed there. Confirmation of Richardson’s hypothesis of sea level rise and settlement loss came in the 1990s, with the discovery and excavation of very early maritime sites such as Quebrada Jaguay (-13,000-8250 cal yr BP), and Quebrada Tacahuay (Keefer et al. 1998; Sandweiss et al. 1998; see Sandweiss, in this volume).
El Nino Frequency Change and Correlated Cultural Change
Another line of environmental archaeological research initiated by Richardson (1973) in far northern Peru is the recognition of changing ocean currents in the Mid-Holocene from the contents of archaeological middens. Over the next thirty years, Richardson and his colleagues pursued this issue, eventually using archaeological mollusk and fish remains to determine likely variations in the frequency of El Nino (ENSO): a period of few or no ENSO events and warmer than present coastal waters in northern Peru from -90005800 cal yr BP; a period of strong but infrequent ENSO events and cool waters along all of Peru from -5800-3000 cal yr BP; and conditions within the modern range since the latter date (Sandweiss et al. 2001). Though these conclusions have been debated, they are now well substantiated by multiple paleoclimatic records throughout the Pacific basin (see summary in Sandweiss 2003). The climatic transition at 5800 cal yr BP correlates with the onset of monumental construction on the Peruvian coast, while the transition at 3000 cal yr BP correlates with the abandonment (at the end of the Initial Period) of the last temples in this tradition after almost 3,000 years of development. Carefully nuanced further research is needed to see if there are any causal or explanatory links in these correlations.
Vulnerability of Agricultural Systems
Agrarian collapse is another research area that highlights human-environment interaction. Plant cultivation began on the coast of Ecuador, over 11,000 years ago (Piperno and Pearsall 1998; Piperno and Stothert 2003) and irrigation systems were in place on the western (Pacific) slopes of northern Peru by about 6000 cal yr BP (Dillehay et al. 2005). In the highlands, the earliest evidence of agriculture dates to the end of the Late Preceramic Period around 4000-3700 cal yr BP in Cotahuasi (Perry et al. 2006), while small-scale irrigation of the interandean valleys in Cajamarca began in the late Initial Period between ca. 3000 and 2500 cal yr BP (Burger 1992: 111). Large-scale terracing and, in the Lake Titicaca region, raised fields were first constructed in the second half of the first millennium AD (ca. 1450-950 cal yr BP). None of these systems was stable in the long term, and some suffered spectacular, precolumbian collapses. The causes for agrarian collapse have been hotly debated, with suggestions for individual cases ranging from tectonic movement to engineering incompetence to climatic change. Space does not permit detailed discussion of case studies, but following are brief references to major examples. In the Moche area of northern coastal Peru, field systems built from the end of the Early Intermediate Period (ca. 200 BC-AD 600 or 2150-1350 cal yr BP) through the early Late Intermediate Period had contracted significantly before the end of the Late Intermediate Period (ca. AD 1100-1440 or 850-510 cal yr BP). Moseley (1983 inter alia) posits tectonically driven landscape alteration as the primary cause of field abandonment, while others suggest human factors (e. g., Pozorski and Pozorski 1982). In far southern Peru, just north of Ilo, Clement and Moseley (1991) document the contraction of a small-scale, spring-fed coastal irrigation system also apparently as the result of tectonic activity during the second millennium AD. In the same area, but slightly further inland, Moseley and colleagues found evidence not only for agrarian collapse but also for radical social reorganization at about AD 1350 (ca. 600 cal yr BP). In the Ilo river valley, a large-magnitude flood associated with El Nino destroyed field systems, the main canal, and most dwellings on the valley slopes and bottoms; along with agrarian contraction and demographic collapse, the local, Chiribaya culture shows significant change in cultural patterns following this event (Reycraft 2000; Satterlee et al. 2001). In the altiplano around Lake Titicaca, during the first millennium AD, raised field agriculture vastly increased the agrarian productivity of this inhospitable, high-altitude environment (e. g., Erickson 1988). Early in the second millennium AD, however, raised field technology was abandoned and not rediscovered until late in the twentieth century. Kolata and his colleagues (e. g., Binford et al. 1997) have argued that the proximate cause of agrarian collapse in this region was climatic change evident in a variety of paleoclimatic archives. Erickson (1999) has questioned their interpretation and the use of what he characterizes as “neo-environmental determinism” in causal explanations of prehistoric Andean culture change.
World History
