Climate, Agricultural Strategies, and Sustainability in the Precolumbian Andes Charles Ortloff [email protected]
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Andean Past Volume 9 Article 15 11-1-2009 Climate, Agricultural Strategies, and Sustainability in the Precolumbian Andes Charles Ortloff [email protected] Michael E. Moseley University of Florida, [email protected] Follow this and additional works at: https://digitalcommons.library.umaine.edu/andean_past Part of the Archaeological Anthropology Commons, Natural Resource Economics Commons, Natural Resources Management and Policy Commons, Sustainability Commons, and the Water Resource Management Commons Recommended Citation Ortloff, Charles and Moseley, Michael E. (2009) "Climate, Agricultural Strategies, and Sustainability in the Precolumbian Andes," Andean Past: Vol. 9 , Article 15. Available at: https://digitalcommons.library.umaine.edu/andean_past/vol9/iss1/15 This Article is brought to you for free and open access by DigitalCommons@UMaine. It has been accepted for inclusion in Andean Past by an authorized administrator of DigitalCommons@UMaine. For more information, please contact [email protected]. CLIMATE, AGRICULTURAL STATEGIES, AND SUSTAINABILITY IN THE PRECOLUMBIAN ANDES CHARLES R. ORTLOFF University of Chicago and MICHAEL E. MOSELEY University of Florida INTRODUCTION allowed each society to design and manage complex water supply networks and to adapt Throughout ancient South America, mil- them as climate changed. While shifts to marine lions of hectares of abandoned farmland attest resources, pastoralism, and trade may have that much more terrain was cultivated in mitigated declines in agricultural production, precolumbian times than at present. For Peru damage to the sustainability of the main agricul- alone, the millions of hectares of abandoned tural system often led to societal changes and/or agricultural land show that in some regions 30 additional modifications to those systems. to 100 percent more terrain was cultivated in precolumbian times than at present (Clement To achieve agricultural sustainability, An- and Moseley 1991:425). While many cultural dean administrators needed to record changes in explanations for agrarian collapse can be formu- climate patterns, weather events, and natural lated, the most compelling reason for the loss of disasters, then conduct analyses to plan modifi- cultivatable land is changing climate, including cations allowing agricultural systems to function shifting rainfall patterns and amounts. Agricul- in the face of changing water supplies. Modifica- ture was expanded many times in many places tions took the form of physical alteration of when conditions favorable to land reclamation existing water delivery systems, and the devel- were perceived by past populations. When opment of new agro-systems suitable to new climatic trends led to diminished water supplies, hydrological conditions. When climate deterio- temporary or permanent agrarian regression rated beyond a system’s ability to make modifi- ensued, with consequences for social structure. cations to maintain sustainability, field system abandonment was an inevitable outcome. A Ancient Andean civilizations utilized a wide sustainable agricultural base, on the other hand, diversity of agricultural techniques in different can lead to overall population growth and ecological zones, and developed agriculural patterns of population concentration and/or strategies consistent with local climate patterns, dispersal, with specialized labor to work and hydrological characteristics, soil and crop types, manage the system. Such a division of the work- and local labor supply. The strategies chosen force underlies urban centers that controlled depended upon a society’s hydraulic engineer- and administered adjacent agricultural zones ing, surveying, and civil engineering skills com- and may have exerted centralized control of bined with its perception of ecological and labor. hydrological conditions. Taken together, these ANDEAN PAST 9 (2009): 277-304. ANDEAN PAST 9 (2009) - 278 Even if water supplies are adequate for high groundwater levels on the altiplano sustainable agriculture, inappropriate strategies throughout wet and dry seasons. Drainage from of agro-engineering and labor management can western cordillera rainfall is mostly directed to interrupt the development of otherwise well- coastal river valleys (Figures 1, 2) with outflow functioning societies. Agricultural sustainability to the Pacific Ocean with the exception of the requires administrative skills to guide adaptive intermontane source of the Santa River. technical innovations in the design and manage- ment of an agricultural system to maintain high Biotic diversity is pronounced in the many yields in spite of changing weather and climate. highly varied ecological zones of Peru. For A degree of flexibility to modify an agricultural example, with 35 of the world’s life zones, Peru system should, therefore, be part of the original contains the largest number of ecological zones design of a system if knowledge of prior weather of any country on earth (Perú, ONERN 1976; and climate patterns, and their consequences for Tosi 1960). However, diversity is asymmetrically sustainability, exists. As an integral part of distributed by altitude, latitude, and longitude. system design and the potential for innovative As in all mountain ranges, ecological zones are and adaptive design change, an understanding stratified by altitude and far fewer species of of the dynamics of water flow from original plants live at high elevations than at low ones. highland rainfall sources to lowland and coastal regions must be in place. The effects of exces- The Andean mountain ranges form South sive rainfall or drought are disproportionately America’s continental divide. Normally, all felt in the highlands compared to the run-off rainfall in the eastern cordillera comes from the dependent coastal field systems. The differences Atlantic Ocean with a longitudinal gradient in arise from altitude-dependent soil types and precipitation. Fronting the Amazon Basin, the their water infiltration and water retention high eastern Andean escarpment receives characteristics, soil saturation levels, and poros- abundant precipitation, creating a rain shadow ity, as well as transport, evaporation, and seep- to the west. Consequently, bio-diversity is age loss rates from water source to final destina- greatest along the lower eastern flanks of the tion for agricultural use. Based upon such con- eastern cordillera. The eastern escarpment is siderations, reconstructions of interactive, exceptionally steep and therefore difficult to climate-related, and societal-dependent struc- farm. Because the eastern watershed reaches tural factors have a hydrological component and deep into the intermontane sierra, it receives are thus key to understanding highland-lowland and discharges approximately 90% of all mois- interactional dynamics and their possible rela- ture in the range. Sierran basins have relatively tion to Andean development. modest slopes amenable to rainfall and runoff farming. Cultivation, in conjunction with the THE SETTING: REGIONAL CLIMATE NORMS use of high altitude grasslands for herding, sustains agro-pastoralism and was the basis for The central Andes consists of parallel east- large sierran populations in prehispanic times. ern and western cordilleras. In the north-central Andes the higher eastern range and the lower DROUGHT EVENTS western range enclose intermontane uplands that drain mostly into the Amazon and its Analysis of the ice cores from the southern tributaries. In the southern altiplano region region Quelccaya peak (Thompson et al. 1985, rainfall drainage is mostly into Lake Titicaca 1986, 1994) and from the north Andean Huas- with a high degree of infiltration that maintains carán mountain (Thompson et al. 1995a), and 279 - Ortloff & Moseley: Agricultural strategies analysis of the Lake Titicaca sediment cores ies we review the record of cultural change (Abbott et al. 1997; Binford et al. 1997; Ortloff through time using the Uhle-Rowe chronologi- and Kolata 1993; Seltzer 1991) reveals dramatic cal sequence. The sequence begins with Forma- climate shifts. The Quelccaya ice cores indicate tive and Preceramic Periods of long duration (c. periods of wet and dry climate, as well as dust 9500-1800 B.C.E.), and continues with the maxima, over a 1500 year span of time. The Initial Period (IP; 1800-900 B.C.E.), the Early Huascarán ice cores show similar climate varia- Horizon (EH; 900-200 B.C.E.), the Early Inter- tions with dust concentration events character- mediate Period (EIP; 200-600 C.E.), and the izing dry periods. The Lake Titicaca sediment Middle Horizon (MH; 600-1000 C.E.). This last cores present limnological data corroborating division is followed by the Late Intermediate the major wet and dry period climate shifts Period (LIP; 1000-1476 C.E.), then climaxed by found in the Quelccaya and Huascarán ice core the Late Horizon (LH; 1476-1534 C.E.). data (Ortloff and Kolata 1993:200). Initial analysis of the cores documents a 25 to 30 Climate data show that early and middle percent decline in precipitation between 563 phases of the EIP climate were sufficiently stable and 594 C.E. (Shimada et al. 1991:261). This to provide adequate water resources for the drought is notable for both its rapid onset and development of canal based irrigation agricul- exceptional severity (Schaaf 1988; Shimada et ture by the Peruvian north coast Gallinazo and al. 1991:248, 261-262). A protracted precipita- Moche polities, as well as by the south coast tion downturn between 1100 and 1500