title: Environmental impact of geometric earthwork construction in pre-Columbian Amazonia.
abstract: There is considerable controversy over whether pre-Columbian (pre-A.D. 1492) Amazonia was largely "pristine" and sparsely populated by slash-and-burn agriculturists, or instead a densely populated, domesticated landscape, heavily altered by extensive deforestation and anthropogenic burning. The discovery of hundreds of large geometric earthworks beneath intact rainforest across southern Amazonia challenges its status as a pristine landscape, and has been assumed to indicate extensive pre-Columbian deforestation by large populations. We tested these assumptions using coupled local- and regional-scale paleoecological records to reconstruct land use on an earthwork site in northeast Bolivia within the context of regional, climate-driven biome changes. This approach revealed evidence for an alternative scenario of Amazonian land use, which did not necessitate labor-intensive rainforest clearance for earthwork construction. Instead, we show that the inhabitants exploited a naturally open savanna landscape that they maintained around their settlement despite the climatically driven rainforest expansion that began ∼2,000 y ago across the region. Earthwork construction and agriculture on terra firme landscapes currently occupied by the seasonal rainforests of southern Amazonia may therefore not have necessitated large-scale deforestation using stone tools. This finding implies far less labor--and potentially lower population density--than previously supposed. Our findings demonstrate that current debates over the magnitude and nature of pre-Columbian Amazonian land use, and its impact on global biogeochemical cycling, are potentially flawed because they do not consider this land use in the context of climate-driven forest-savanna biome shifts through the mid-to-late Holocene.
authors.affiliation: Department of Geography and Environmental Science, University of Reading, Whiteknights, Reading RG6 6AB, United Kingdom;School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, United Kingdom; j.f.carson@reading.ac.uk.
authors.forename: John Francis
authors.initials: JF
authors.lastname: Carson
authors.affiliation: School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, United Kingdom;
authors.forename: Bronwen S
authors.initials: BS
authors.lastname: Whitney
authors.affiliation: Department of Geography and Environmental Science, University of Reading, Whiteknights, Reading RG6 6AB, United Kingdom;
authors.forename: Francis E
authors.initials: FE
authors.lastname: Mayle
authors.affiliation: Department of Archaeology, University of Exeter, Exeter EX4 4QE, United Kingdom;
authors.forename: José
authors.initials: J
authors.lastname: Iriarte
authors.affiliation: Kommission für Archäologie Aussereuropäischer Kulturen, Deutsches Archäologisches Institut, 53173 Bonn, Germany; and.
authors.forename: Heiko
authors.initials: H
authors.lastname: Prümers
authors.affiliation: Herbario del Oriente Boliviano, Museo de Historia Natural 'Noel Kempff Mercado,' Universidad Autónoma Gabriel René Moreno, Casilla 2489, Santa Cruz, Bolivia.
authors.forename: J Daniel
authors.initials: JD
authors.lastname: Soto
authors.affiliation: Department of Archaeology, University of Exeter, Exeter EX4 4QE, United Kingdom;
authors.forename: Jennifer
authors.initials: J
authors.lastname: Watling
mesh_terms: D001838:Bolivia; D002606:Charcoal; D017753:Ecosystem; D004777:Environment; D005843:Geography; D060106:Lakes; D011058:Pollen; D011891:Rain; D013997:Time Factors; D014197:Trees / Q000502:physiology*
chemical_list: D002606:Charcoal
keywords: Amazon rainforest; Amazonian archaeology; Anthropocene; human–environment interactions; paleoecology