Pre-Columbian population of the Monumental Mound Region, Bolivia

Funded by the Natural Environment Research Council, SCENARIO DTC

Joe Hirst

Supervised by Frank Mayle, Joy Singarayer (University of Reading) and Umberto Lombardo (University of Bern)


Greater Amazonia is currently at the centre of a highly contentious debate concerning the environmental impact of its pre-Columbian inhabitants. In recent decades, the traditional view of Amazonia as an untouched wilderness inhabited by sparse populations [1,2] has been challenged by multiple discoveries of monumental earthworks [3,4]. This revelation has led some to propose that certain pre-Columbian societies were able to achieve dense populations, create urban landscapes and substantially alter regional ecosystems through deforestation and the use of fire [5].

A related question is the extent of the legacy of these societies, especially when given the relative overabundance of economically-useful species within the lowland rainforest [5–7]. Additionally, post-contact societal collapse has previously been used to account for subsequent decreases in global atmospheric CO2, as well as rebounds in the abundance of certain species of flora and fauna [8,9].

However, despite the profound importance of answering these questions, generating consistent estimates for the size of pre-Columbian populations within Amazonia has proved challenging. The associated difficulties and methodological disagreements have resulted in basin-wide estimates ranging from between 0.5 million to -20 million people [10,11].

As part of my 3-year PhD project to determine the impacts of pre-Columbian activity within the Monumental Mound Region (MMR) of the Llanos de Mojos, I will be developing an Agent-based model (ABM) to generate hypotheses regarding its pre-Columbian population size and land-use. The Llanos de Mojos plays a central role within the aforementioned debate, having been extensively modified with pre-Columbian earthworks [3]. Some propose that pre-Columbian societies within the region could have been densely populated and had an extensive environmental impact [5,12]. However, the few peer-reviewed estimates available are highly inconsistent, ranging from 0.15 to 2.0 persons per km2 [13–15].

Developing an ABM enables me to tackle this problem of population from a novel perspective: that of individual households, their behaviour, and their spatially limited access to resources on the landscape. In order to survive and reproduce, each household will need to satisfy their demand for a variety of resources. To do this, they will be able to claim and convert patches of land into cropland and agroforestry, providing the necessary resources for survival. This behaviour will be informed by dynamic land use and elevation data, initialised from empirical observations. By comparing results from the model to estimates obtained utilising different methodologies (Architectural Energetics and Carrying Capacity), I aim to constrain the existing range of values and thereby improve our understanding of the MMR’s pre-Columbian population size.


An example of one of the earthen mounds that characterise the MMR, each thought to represent an individual pre-Columbian settlement. The mounds were deliberately constructed through the excavation and transportation of earth by the region’s inhabitants [16].

The model is currently under construction.

An initial implementation of pre-Columbian settlements onto the landscape of the Mound Region Model. Land patches have been shaded according to their elevation, using data collected by the Shuttle Radar Topography Mission [17]. Darker shades of green represent higher ground. Each settlement is represented as a black circle [18].

Further Reading

  1. Meggers, B. Environmental Limitution on the Development of Culture. Am. Anthropol. 12, 304–325 (1954).

  2. Gross, D. R. Protein Capture and Cultural Development in the Amazon Basin. Am. Anthropol. 77, 526–549 (1975).

  3. Denevan, W. M. The Aboriginal Cultural Geography of the Llanos De Mojos of Bolivia. (University of California Press, 1966).

  4. Heckenberger, M. et al. Amazonia 1492: Pristine forest or cultural parkland? Science (80-. ). (2003) doi:10.1126/science.1086112.

  5. Balée, W. & Erickson, C. Time and Complexity in Historical Ecology: Studies in the Neotropical Lowlands. (Colombia University Press, 2006).

  6. Ter Steege, H. et al. Hyperdominance in the Amazonian tree flora. Science (80-. ). 342, 325–333 (2013).

  7. Levis, C. et al. Persistent effects of pre-Columbian plant domestication on Amazonian forest composition. Science (80-. ). 358, 925–931 (2017).

  8. Denevan, W. M. After 1492: Nature Rebounds. Geogr. Rev. 106, 381–398 (2016).

  9. Koch, A., Brierley, C., Maslin, M. M. & Lewis, S. L. Earth system impacts of the European arrival and Great Dying in the Americas after 1492. Quat. Sci. Rev. 207, 13–36 (2019).

  10. Newson, L. A. The Population of the Amazon Basin in 1492: A View from the Ecuadorian Headwaters. Trans. Insitute Br. Geogr. 21, 5–26 (1996).

  11. Denevan, W. M. Rewriting the late pre-European history of Amazonia. J. Lat. Am. Geogr. 11, 9–24 (2012).

  12. Mann, C. . Earthmovers of the Amazon. Science (80-. ). 287, 786–789 (2000).

  13. Denevan, W. M. The Native Population of the Americas in 1492. (University of Wisconsin Press, 1992).

  14. Steward, J. The Native Population of South America. ed. J. in Handbook of South American Indians (ed. Steward, J.) 655–668 (Bureau of American Ethnology: Smithsonian Institution, 1949).

  15. Steward, J. & Faron, L. Native Peoples of South America. (McGraw-Hill, 1959).

  16. Lombardo, U., Denier, S., May, J. H., Rodrigues, L. & Veit, H. Human-environment interactions in pre-Columbian Amazonia: The case of the Llanos de Moxos, Bolivia. Quat. Int. 312, 109–119 (2013).

  17. Void-filled Elevation data was collected in 2000 by Shuttle Radar Topography Mission (SRTM, 2014), maintained by the NASA EOSDIS Land Processes Distributed Active Archive Center (LP DAAC) at the USGS Earth Resource Observation and Science (EROS) Center, Sioux Falls, South Dakota

  18. Lombardo, U. & Prümers, H. Pre-Columbian human occupation patterns in the eastern plains of the Llanos de Moxos, Bolivian Amazonia. J. Archaeol. Sci. 37, 1875–1885 (2010).


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