Pre-Columbian Earthworks in the Riberalta Region of the Bolivian Amazon

Interpretations of the Amazonia prehistory have changed significantly in the last few decades, as the complexity and diversity of the Amazonian cultures are beginning to be documented and understood. Earthworking, a long-term conscious anthropogenic landscape alteration, was a widespread phenomenon throughout the South American tropical lowlands. A variety of earthworks has been documented in the Southwest Amazon, including ditches and embankments of different shapes and sizes, roads, extensive raised fields, canals, causeways, and artificial wetlands linked to adjacent mounds and forest island settlement sites. A field survey and test excavations were undertaken in the region of Riberalta, in the Bolivian Amazon. The purpose of these investigations was to study the distribution and characteristics of the pre-Columbian occupation in the region. We found different types of sites, some without visible earthworks, indicating fairly dense occupation on river bluffs and terra firme, but lacking long permanence in the same location. The earthwork tradition prevailed in the Riberalta region from at least 100 B.C. until the period of European contact. The function of the less-complex earthworks may have been to enclose the occupation areas, and in some cases, to serve as canals. Compared to the variable layout of the sites, the ceramic assemblages of the region are relatively homogeneous. A central objective for future research will be to determine if the earthwork sites correlate with a single or multiple cultural traditions.Key-words: Southwest Amazonian archaeology, earthworks, ceramic traditions

Esikolumbiaaniset maarakennemuinaisjäännökset Brasilian ja Bolivian rajaseudulla, Lounais-Amazonialla

Amazonian earthworks have a variety of forms and sizes, and are found in different geographical and ecological locations, indicating separate time periods, distinct cultural affiliations, and diverse functions. Because research on pre-Columbian earthworks has only recently begun, a number of basic questions concerning the function and chronology of these structures, and the ethno-cultural and socio-political relationships of the societies who created them still remain unanswered. The main aim of this dissertation, consisting of four peer-reviewed articles and a synthesis paper, is to build new knowledge and expand on the existing, but still noticeably sparse data on the region's pre-Columbian earthworking cultures. It proposes a hypothesis of the existence of relatively early sedentary interfluvial populations with rather organized and peculiar societal and ideological systems in the southwestern Amazon. This suggestion challenges the conventional view of ancient Amazonian peoples being non-sedentary, with an egalitarian social organization and an inability to alter and manage the environment in which they lived. This dissertation presents and discusses the results of archaeological fieldwork undertaken at earthwork sites in two neighboring frontier regions in the southwestern Amazon: the region of Riberalta in Bolivia and the eastern state of Acre in Brasil. The Bolivian sites are interpreted as permanent settlements, while the Acrean earthworks were constructed principally for ceremonial purposes. The earthworks documented in the Riberalta region are structurally simpler than the ones studied in Acre and are found in slightly different locations, e.g., on high river bluffs or inland only a few kilometers from the main rivers. In Acre, the sites are located on high interfluvial plateaus near minor watercourses. The earthwork building practice prevailed in the Riberalta region from around 200 B.C. until the period of European contact, whereas the geometric earthwork tradition began earlier in Acre, around 1200 B.C., if not before. By the tenth century A.D., the regional confederation that created the geometric enclosures was already disintegrating. Even so, some sites apparently remained in use until the fourteenth century A.D. Chronologically and culturally, these earthworking peoples were formative-stage societies demonstrating emerging sedentism and evolving socio-organizational structures, and in Acre in particular, a society united by a highly developed ideological system materialized in the geometric enclosure architecture.Kiinteitä maarakennemuinaisjäännöksiä tunnetaan eri maantieteellisiltä alueilta ja ekologisilta vyöhykkeiltä Amazonialla. Ne ovat tyypiltään varsin vaihtelevia, joko yksittäisiä kaivantoja ja maavalleja tai useiden erimuotoisten, yleisimmin pyöreiden tai neliömäisten, kaivantojen muodostamia laajempia kokonaisuuksia, ja heijastavat historian eri ajanjaksoja, kulttuureja sekä käyttötarkoituksia. Tutkimuksen ollessa vasta aluillaan, maarakenteiden käyttötarkoitus ja kronologia, rakenteet aikaansaaneiden ryhmien etnis-kulttuurinen tausta sekä sosiopoliittiset suhteet muihin Amazonian esikolumbiaanisiin kulttuureihin ovat kysymyksiä, joihin ollaan toistaiseksi vasta etsimässä vastauksia. Väitöskirjan, joka koostuu neljästä vertaisarvioidusta artikkelista sekä synteesiartikkelista, päätavoitteena on tuottaa uutta sekä laajentaa jo olemassa olevaa, mutta vielä vähäistä tietoa Lounais-Amazonian esikolumbiaanisista maarakennekulttuureista. Väitöskirjassa esitetään hypoteesi suhteellisen varhaisen pysyväluontoisen asumismuodon sekä organisoituneen yhteiskunnallisen ja ideologisen järjestelmän omaavan väestön, tai jopa sivilisaation, olemassaolosta Lounais-Amazonian terra firme -alueilla. Tämä oletus haastaa perinteisen näkemyksen Amazonian kansoista hajanaisten ravintoresurssien perässä alati liikkuvina pieninä, löyhästi organisoituneina ryhminä, joilla ei ollut keinoja hallita ja muokata elinympäristöään. Väitöskirjassa esitetään Brasilian Acren osavaltion itäosassa ja bolivialaisen Riberaltan kaupungin ympäristössä maarakennekohteilla suoritettujen arkeologisten kenttätöiden tulokset. Bolivian kohteet tulkitaan pysyviksi asuinpaikoiksi, kun taas Acren maanrakenteilla oli pääasiassa seremoniallinen käyttötarkoitus. Riberaltan alueella dokumentoidut kiinteät muinaisjäännökset ovat rakenteellisesti yksinkertaisempia kuin Acressa ja sijaitsevat jokien rantaterasseilla tai sisämaassa muutaman kilometrin päässä jokilaaksoista. Acren maarakennekohteet taas keskittyvät jokien välisille tulvimattomille ylätasangoille. Maanrakennekohteet Riberalta alueella ajoittuvat 200 eKr. lähtien aina eurooppalaisen valloituksen ajan alkuun saakka. Acressa geometrinen maanrakennetraditio alkoi aiemmin, viimeistään noin 1200 eKr., mutta jo 900-luvulla alueellinen liittouma, joka loi geometriset maarakenteet, oli hajoamassa vaikkakin joitain kohteita ilmeisesti käytettiin jopa 1300-luvulle saakka. Maarakennekulttuurit olivat kehittyvien toimeentulostrategioiden ja yhteiskunnallisten organisaatiorakenteiden murrosvaiheessa. Lisäksi Acressa yhteisöt yhdisti pitkälle kehittynyt alueellinen ideologinen järjestelmä, joka materialisoitui geometristen maarakenteiden arkkitehtuurissa

Diversity of Pre-colonial Earthworks in the Brazilian State of Acre, Southwestern Amazonia

Amazonian earthworks, which are an important testimony to ancient anthropogenic landscape modifications, have a significant variety of structures and sizes, and are found in different geographical and ecological locations that indicate separate time periods, distinct cultural affiliations, and diverse purposes. We introduce data from diverse archaeological earthwork sites, geoglyphs, mound sites, and walled enclosures situated in the interfluves of the Purus River in the Brazilian state of Acre and propose a type definition for these sites. The abundant anthropogenic landscape features and their associated material culture indicate considerable human-induced environmental alterations and diverse earthworking traditions that are characteristic of the region of eastern Acre from at least ca. 2000 b.p. onwards.Peer reviewe

Historical ecology, human niche construction and landscape in pre-Columbian Amazonia: a case study of the geoglyph builders of Acre, Brazil

This paper applies concepts from the fields of historical ecology and human niche construction theory to interpret archaeological and palaeoecological data from the Brazilian state of Acre, southwest Amazonia, where modern deforestation has revealed hundreds of pre-Columbian monumental earthworks called 'geoglyphs', largely built between ca. 2000–650 cal. BP (calibrated years before present). Our main objective was to move away from the debate which currently dominates Amazonian archaeology over large- vs. small-scale pre-Columbian environmental impacts, and instead offer a more nuanced interpretation of human-environment interactions in our specific study area. Despite the difficulties presented by working with an incomplete regional archaeological dataset, interpreting our findings in light of these theoretical frameworks allowed us to re-think landscape history and ask new questions about a possible relationship between anthropogenic forests, symbolic capital and monument building in our particular study area

Impact of pre-Columbian 'geoglyph' builders on Amazonian forests

Over 450 pre-Columbian (pre-AD1492) geometric ditched enclosures ('geoglyphs') occupy ca. 13,000 km2 of Acre state, Brazil, representing a key discovery of Amazonian archaeology. These huge earthworks were concealed for centuries under terra firme (upland interfluvial) rainforest, directly challenging the 'pristine' status of this ecosystem and its perceived vulnerability to human impacts. We reconstruct the environmental context of geoglyph construction and the nature, extent and legacy of associated human impacts. We show that bamboo forest dominated the region for ≥6000 y and that only small, temporary clearings were made to build the geoglyphs; however, construction occurred within anthropogenic forest that had been actively managed for millennia. In the absence of widespread deforestation, exploitation of forest products shaped a largely forested landscape that survived intact until the late 20th century

Pre-Columbian land use in the ring-ditch region of the Bolivian Amazon

The nature and extent of pre-Columbian (pre-1492 AD) human impact in Amazonia is a contentious issue. The Bolivian Amazon has yielded some of the most impressive evidence for large and complex pre-Columbian societies in the Amazon basin, yet there remains relatively little data concerning the land use of these societies over time. Palaeoecology, when integrated with archaeological data, has the potential to fill these gaps in our knowledge. We present a 6,000-year record of anthropogenic burning, agriculture and vegetation change, from an oxbow lake located adjacent to a pre-Columbian ring-ditch in north-east Bolivia (13°15’44” S, 63°42’37” W). Human occupation around the lake site is inferred from pollen and phytoliths of maize (Zea mays L.) and macroscopic charcoal evidence of anthropogenic burning. First occupation around the lake was radiocarbon dated to ~2500 years BP. The persistence of maize in the record from ~1850 BP suggests that it was an important crop grown in the ringditch region in pre-Columbian times, and abundant macroscopic charcoal suggests that pre-Columbian land management entailed more extensive burning of the landscape than the slash-and-burn agriculture practised around the site today. The site was occupied continuously until near-modern times, although there is evidence for a decline in agricultural intensity or change in land use strategy, and possible population decline, from ~600-500 BP. The long and continuous occupation, which predates the establishment of rainforest in the region, suggests that pre-Columbian land use may have had a significant influence on ecosystem development at this site over the last ~2000 years

Visualization and Movement as Configurations of Human-Nonhuman Engagements : Precolonial Geometric Earthwork Landscapes of the Upper Purus, Brazil

Producing geometric designs and images on materials, such as pottery, basketry, and bead artwork, as well as the human body, is elemental and widespread among Amazonian Indigenous peoples. In this article, we examine the different geometric forms identified in the precolonial geoglyph architecture of southwestern Amazonia in the context of geometric design making and relational ontologies. Our aim is to explore earthwork iconography through the lens of Amerindian visual arts and movement. Combining ethnographic and archaeological data from the Upper Purus, Brazil, the article shows how ancient history and socio-cosmology are deeply "written" onto the landscape in the form of geometric earthworks carved out of the soil, which materialize interactions between nonhuman and human actors. We underline skills in visualization, imaginative practices, and movement as ways to promote well-balanced engagements with animated life forms. Here, iconography inserted in the landscape is both a form of writing and also emerges as an agent, affecting people through visual and corporal practices.Peer reviewe