Raised Field Abandonment in the Upper Amazon

Research Report Raised Field Abandonment in the Upper Amazon such as manioc, produce well under these conditions, but they require dry soils or they will rot. Raised fields provide improved soil conditions for such crops. Prehispanic farmers changed the ecology of the savanna by constructing raised fields. Part of the area drained by a small river, the Iruyanez, was surveyed for remains of this agricultural system. The Iruyanez is a tributary of the Mamor£, which is in turn a tributary of the Madeira, one of the main rivers of the Amazon system. In this area of about 400 square kilometers, a single type of earthwork was built—large shallow raised fields (Denevan 1966). These fields average about 200 meters in length by 20 meters in width by less than one-half meter in John H. Walker John H. Walker is on staff at the University of Pennsylvania Museum of Archaeology and Anthropology. In the Amazon Basin, an historical perspective has the potential to transform the image of indigenous peoples. The people and cultures of the Amazon Basin are dynamic, and anthropological archaeology can help show how and why they have changed over time. An example of cultural change is the abandonment of an agricultural system in the lowlands of eastern Bolivia. At one scale, this transformation was very rapid. Archaeological evidence of the use of raised fields in the 15th century A.D. contrasts with the lack of written records of the practice in the late 17th century A.D. Focusing on individual intensive farmers, this two hundred-year period is equal to perhaps eight generations. The decisions made by these eight generations of farmers make up the explanatory factor in a short-term point of view. At both the small and large scales, explanation depends on the details of the distinctive context of raised-field agriculture, and the consequences of European contact. The research described here is part of the AgroArchaeological Project of the Beni, a cooperative effort of the National Institute of Archaeology of Bolivia and the University of Pennsylvania (Erickson, Esteves, and Michel 1991). Fifteen months were spent in the field, from the fall of 1996 through 1997. The marked seasonality of the climate makes year-long field-work important for understanding how seasonal cycles affect settlement pattern and agricultural potential. A more detailed overview of the project, including a review of theories of agricultural change as well as other case studies, is available elsewhere (Walker 1999). The environment of eastern Bolivia is dominated by the Llanos de Moxos, a seasonal wetland about the same size as the Yucatan peninsula, or the nation of Syria (Figure 1). With a year-long growing season and plentiful rainfall, the main problem faced by farmers is seasonal flooding. The landscape changes dramatically from the dry season to the wet season. In August, many arroyos run dry, rivers are easily crossed on foot, and the haze from prairie fires gives color to sunrise and sunset. In February, rivers and arroyos overflow their banks, heavy rains saturate the ground, and as much as 50 percent of the landscape is underwater. Many root crops, Culture & Agriculture Figure 1 Location of the Llanos de Moxos in Eastern Boliva 11 Vol. 22, No. 2 Summer 2000 height (Figure 2). These fields cover a substantial percentage of the total land area. Fields and their associated canals cover roughly 40 square kilometers, which amounts to about 10 percent of the landscape. These fields represent the investment of labor in the improvement of agricultural conditions, and are direct evidence of intensive agriculture. Remains of settlement arefoundprimarily on high ground near the rivers, overlooking the gallery forest. Test excavations were used to obtain chronological information from several of these sites, and to document material culture. Radiocarbon dates were obtained from two sites (Table 1), both of which are associated with raised fields, although their ceramic assemblages were distinct from one another. Five dates from cultural strata in the first site calibrate to the 5th and 6lh centuries A.D. Two dates, one from sterile soil, calibrate to the 5th millennium B.C., and are not interpreted to be associated with the other dates. From the second site, eight dates from cultural strata calibrate to the 14th and 15th centuries A.D., and the range of one of those dates extends to 1645 A.D. The later dates calibrate to within 100 years of the arrival of Columbus. Together with the lack of written evidence of field use, they force the consideration of the Conquest as a factor in the abandonment of raised-field agriculture. Historical research has demonstrated that the Conquest was the source of many changes in agricultural conditions in eastern Bolivia (Block 1994b). The first was the depopulation produced by epidemics of Old World diseases. Debate on the magnitude of the epidemics has produced estimates of mortality for indigenous American populations that range from 60 percent to more than 90 percent (Denevan 1992a). Even if the lowest estimate were halved, the deaths of such a large percentage of the producers and consumers in an agricultural system would significantly change the ratio of land to labor. It would have reduced the number of people available for community labor projects and in some cases would have led directly to the abandonment of raised fields, through the death of entire farming communities. Figure 2 Raised Fields along the Rio Iruyanez, in the Llanos de Moxos - Culture & Agriculture Vol. 22, No. 2 Summer 2000 Table 1 Radiocarbon Dates and Calibrations from the Rio Iruyanez Sample Number Sample Context Laboratory Number Radiocarbon Age B.P. A.D. B.C. Cerro Site, Trench 3 ECC-17 charcoal ECC-4 charcoal ECC-3 charcoal ECC-15 charcoal ECC-22 charcoal ECC-14 charcoal ECC-18 charcoal ECC-21 charcoal 117221 117218 AA30388 AA30389 AA30392 117220 AA30390 AA30391 470 ± 90 480 ± 50 535 ± 45 570 ± 45 600 ± 45 610 ±70 620 ± 40 620 ± 40 1480 1470 1415 1380 1350 1340 1330 1330 San Juan Site, Trench 2 SJV-1 charcoal SJV-2 charcoal SJV-6 charcoal charcoal SJV-4 charcoal SJV-5 AA30383 AA30384 AA30386 AA30385 117223 1475 ±55 1530 ± 45 1550 ± 45 1560 ± 45 1560 ±50 475 420 400 390 390 San Juan Site, Trench 2 charcoal SJV-3 charcoal SJV-7 117222 AA30387 5740 ± 40 5825 ± 70 Calibrated Date (2-sigma) A.D. A.D. A.D. A.D. A.D. A.D. A.D. A.D. 1305(1438) 1400(1436) 1311 (1413) 1302(1403) 1295 (1328, 1281 (1322, 1292 (1315, 1292 (1315, 1644 1484 1446 1437 1333, 1395) 1428 1340, 1393) 1439 1347, 1390) 1412 1347, 1390) 1412 A.D. 446 (607) 665 A.D. 426 (548) 637 A.D. 418(541)623 A.D. 414(538)613 A.D. 410(538)622 3790 3875 B.C. 4714(4557)4467 B.C. 4894(4714)4509 Stuiver, M. and Heimer, P.J., 1993, Radiocarbon, 35, p. 215-230. Second, coincident with the spread of disease was the spread of metal tools, especially axes and machetes (Metraux 1959). Such tools were easily transported and high in value, and were found well in advance of the frontier of face-toface contact (DeBoer 1986). Anthropological research in New Guinea shows the transforming effects of metal technology in culture contact situations (Salisbury 1962). Tools move quickly through trade networks, and native Amazonians seem to have fit axes in particular into their political and kinship relations. Cultural anthropologists working in the Amazon Basin, notably Brian Ferguson, have noted how political alliances and conflicts interact with differential access to supplies of metal tools (Ferguson 1995). Third, in addition to their roles within the larger culture, the tools likely had a significant impact on agriculture itself. Metal tools, especially metal axes, are a substantial improvement on stone tools for the agricultural tasks of felling trees and clearing vegetation (Denevan 1992b; Mathieu and Meyer 1997). Denevan has argued that slash-and-burn farming in the Amazon Basin may not have been feasible before the arrival of metal tools. With the use of metal axes and machetes, individual households can become more independent, as a single family can clear and plant a slash-and-burn plot. In contrast, more people were required for clearing a field with other methods, or for building a raised field. Many Culture & Agriculture authors have also noted how the advent of metal tools changes the division of labor by gender (Guyer 1988). Finally, new plant and animal species introduced by the Spanish also changed the ecology of agriculture (Block 1994a). In particular, cows and horses were important in the Llanos de Moxos, where herding became a large part of mission agriculture. Mission residents were described as skilled herders, and tallow and hides were important in the economy of the missions. Cattle were important as the foundation of an alternative herding economy, but because of the damage that they did to other crops. Herds of cattle, both managed and feral, frequent the high ground near the rivers. Since this is where most raised fields are located, whether by eating them or trampling them herds of cattle would have damaged raised-field crops. Overall, the effects of the European contact can be seen as a set of new conditions that discouraged the use of raised fields, and which encouraged other agricultural techniques. High mortality reduced population density, and crosscultural research suggests that population density and agricultural intensity are associated (Netting 1993). Conditions of reduced population would have discouraged the use of more intensive raised fields that require communal labor for their construction, and would have favored the use of more extensive systems. These systems were made possible by the 29 Vol. 22, No. 2 Summer 2000 population of 2.1 million people (Klein 1992:122). Clearly, the abandonment of raised fields during this time was a choice made by raised-field farmers. They had the option of continuing to farm raised fields, and they also had the option to live outside the missions. The effects of the Conquest comprise changes, which, over the long term, favored the abandonment of raised fields. Though the establishment of mission outposts throughout Moxos brought metal tools and smallpox to the immediate neighborhood of raised-field farmers, it was the creation of new agricultural alternatives that spelled the end of raised-field farming. New crops and domesticated animals were used in new ways by the farmers to produce the goods desired by the mission economy, as well as to produce food for local subsistence. Abandonment was not a response to declining yields from raised fields, or only a response to a smaller ratio of people to land. Nor was there a political structure that could enforce agricultural change on farmers. Indeed, modern nation states have discovered that even an industrial military can enforce agricultural change only in a limited way. The abandonment was a choice made by farmers under a variety of constraints, and it was part of a cultural change of great magnitude. The archaeological study of the landscape shows that the prehispanic inhabitants pursued a way of life very different from both modern indigenous groups and the residents of the 17th century missions. During the colonial period, when farmers adopted metal tools into their trade and agricultural relationships, the choices they made led to the de-emphasis and eventually the abandonment of raised fields. The biological consequences of the conquest for Native American people and ecology were critical to this process. The people of the Llanos de Moxos were intensive farmers who had largely abandoned their agricultural system by the time they came to the attention of anthropologists. As a result, models of prehispanic cultures that are taken exclusively from history and ethnography necessarily fail to incorporate this important aspect of life in Moxos. The integration of history, ethnography, and archaeology is necessary to fully appreciate the complex heritage of native Amazonians. introduction of metal tools. Such tools allowed the rapid clearance of forest vegetation for swidden cultivation, even by individual households. The introduction of cattle discouraged raised-field use through the destructive effects of herding, and also encouraged a new way of life based on ranching. Furthermore, within the missions themselves, raised fields may also have been less effective for the crops that were emphasized in the new economy, including such annual crops as sugarcane, cacao and rice, in contrast to manioc, which is a perennial crop (Block 1994). If raised fields were designed to maintain dry soils throughout the year, then they might have been less useful for these crops.1 Also, the presence of the Jesuits could have exerted pressure against the use of raised fields in other powerful but indirect ways. For example, raised-field construction probably depended on the organization of labor in communal work parties. If this organization used feasting to mobilize workers, then mission life would have been in conflict with field construction and maintenance, since the priests seem to have objected to the drinking and feasting which accompanied such communal agricultural labor (Maurtua 1906). The Jesuit system was concerned with community labor, but in the missions the relationship between the individual worker and the larger community was constructed in a new way. However, this explanation of change is incomplete. The abandonment of raised-field farming did not automatically follow from these changes in agricultural conditions. Farmers had other options that they could have pursued, both within the mission system, or by remaining outside of it. For example, within the missions, the new tools could have been used to improve raised-field farming, by speeding the construction and maintenance of raised fields. Many of the mission settlements in Moxos are built on top of areas of field platforms. Farmers living in the Missions need not have abandoned the technology. However, the farmers who entered the mission system, for whatever reasons, apparently became herders and swidden farmers. Whether to move into the missions at all may have been the more important choice. The ethnographic and historical record shows that not all indigenous groups chose to enter colonial society. From Moxos, the Siriono are one group who did not enter the mission system (Holmberg 1960; Stearman 1987). Throughout the mission period, incidents of raiding and contact with outside groups make it clear that many people lived outside the mission towns. The number of people who lived outside of the European settlements is a question that must be addressed by archaeological research focusing on the 16th, 17th, and 18th centuries. As late as 1846, Bolivia's first national census estimated that 700,000 "ungoverned Indians" lived in the eastern lowlands, out of a total Culture & Agriculture Acknowledgments The dissertation research described here was made possible by grants from the National Science Foundation, the Wenner-Gren Foundation for Anthropological Research, and the Institute for International Education and the Fulbright Commission. The AgroArchaeological Project of the Beni is a joint project of the National Institute of Archaeology of Bolivia and the University of Pennsylvania, and it is directed by Dr. Clark L. Erickson. Field work would not have been possible without the collaboration and support of the people of Santa Ana del Yacuma and of Exaltaci6n, Provincia Yacuma, Departamento del Beni, Bolivia. 30 Vol. 22, No. 2 Summer 2000 Notes Guyer, Jane 1988 The Multiplication of Labor: Historical Methods in the Study of Gender and Agricultural Change in Modern Africa. Current Anthropology 29(2): 247-272. 1. In modern agricultural experiments, rice is selected by Moxos farmers for planting, not on the fields, but in the neighboring canals. Holmberg, Allan R. 1960 Nomads of the Long Bow: The Siriono of Eastern Bolivia. Chicago: University of Chicago Press. References Cited Block, D. 1994 Mission Culture on the Upper Amazon: Native Tradition, Jesuit Enterprise and Secular Policy in Moxos, 1660-1880. Lincoln: University of Nebraska Press. Klein, Herbert S. 1992 Bolivia: The Evolution of a Multi-Ethnic Society. New York: Oxford University Press. DeBoer, Warren R. 1986 Pillage and Production in the Amazon: A view through the Conibo of the Ucayali Basin, Eastern Peru. World Archaeology 18(2):231-246. Mathieu, James R., and Daniel A. Meyer 1997 Comparing Axe Heads of Stone, Bronze, and Steel: Studies in Experimental Archaeology. Journal of Field Archaeology 24:333-351. Denevan, William M. 1966 The Aboriginal Cultural Geography of the Llanos de Mojos of Bolivia. Volume 48. Berkeley: University of California Press. 1992b Stone vs. Metal Axes: The Ambiguity of Shifting Cultivation in Prehistoric Amazonia. Journal of the Steward Anthropological Society 20(l-2):153-165. Maurtua, Victor M. 1906 Juicio de limites entre el Peru y Bolivia: prueba peruana. 12 Vols. Barcelona: Imprenta de Henrich Y Comp. Metraux, Alfred 1959 The Revolution of the Ax. Diogenes 25:28-40. Netting, Robert McC. 1993 Smallholders,Householders:FarmFamiliesand the Ecology of Intensive, Sustainable Agriculture. Stanford: Stanford University Press. Denevan, William M,, ed. 1992a The Native Population of the Americas in 1492. Madison: University of Wisconsin Press. Erickson, J. Esteves, and M. Michel 1991 Estudio preliminar de los sistemas agricolas precolombinos en el Departamento del Beni, Bolivia: informe de los trabajos de campo efectuados durante el mes de julio de 1990. Instituto Nacional de Arqueologia de Bolivia, Documentos Internos. Salisbury, Richard F. 1962 From Stone to Steel: Economic Consequences of a Technological Change in New Guinea. London: Cambridge University Press. Stearman, Allyn MacLean 1987 No Longer Nomads: The Sirion6 Revisited. Lanham,MD: Hamilton Press. Ferguson, R. Brian 1995 Yanomami Warfare: A Political History. Sante Fe, NM: School of American Research Press. Culture & Agriculture Walker, John H. 1999 Agricultural Change in the Bolivian Amazon. Ph.D. dissertation, University of Pennsylvania. 31 Vol. 22, No. 2 Summer 2000