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Refining the Chronology and Occupation Dynamics of the Mound Villages of South-Eastern Acre, Brazil
Abstract
This paper summarises recent test excavations at five Mound Village sites in the south-eastern sector of Acre state, Brazil, including Caboquinho, Boa Esperança, Tocantins, Dos Circulos IV and V. Radiocarbon dates obtained from the excavation of this site refine the chronology of this archaeological tradition. To improve the chronologies of the mound villages in Acre for which radiocarbon dates were available, we modelled them using Bayesian statistics. We conducted the analysis in ChronoModel, which is better suited for regional models. Bayesian modelling of new radiocarbon dates from basal contexts of nine sites in the region establish the beginning of this archaeological tradition at ~ AD 952-1216. Nine dates from ten construction phases at the Caboquinho site establish the longest sequence from ~ AD 1169-1309 to colonial times. The stratigraphy of the test units reported in this study confirms previous results indicating that mounds are the result of alternating construction and occupation episodes. Dates from the Dos Circulos IV Rectangular Mound Village ~ AD 1367-1451 indicates that Rectangular Villages are broadly contemporaneous with Circular Mound Villages. Single dates from three superimposed villages at Dos Circulos V suggest the succession of village construction. Overall, these preliminary results make a contribution to a better understanding of the timing of emergence and demise of Mound Village construction.
... Archaeological excavations indicate that numerous structures likely served as ceremonial centers, with the main population living in scattered areas with less clear archaeological evidence Virtanen and Saunaluoma 2017;Ranzi and Pärssinen 2021). Another type of patterned earthwork in the region is mound villages with separate mounds surrounding a central plaza (Saunaluoma et al. 2018;Iriarte et al. 2021). ...
... We occasionally consulted oblique-view aerial photographs (Supplementary Material, Figure S1), along with our available field notes. In some cases, we opportunistically used available LiDAR imagery from Iriarte et al. (2021) and from the Sustainable Landscapes Brazil Project (https://www. paisagenslidar.cnptia.embrapa.br/webgis/). ...
... The sudden emergence of mound village culture appears to have been dramatic; however, the proximity of many mound sites to older ceremonial centers suggests that they may have retained some significance in community life. Mound sites were utilized for well over 500 years (Iriarte et al. 2021;Saunaluoma et al. 2021), yet their small size and geographically limited distribution may suggest a population decline, or at the very least, a considerable reduction in the visible traces of their presence. We do not fully understand these aspects at the moment, and they need to be studied carefully in the future. ...
Geometric earthworks are evidence of ancient human activity in western Brazilian Amazonia. We used a review of existing and new data to map earthworks across 27,569 km² of deforested areas in southwestern Amazonia using satellite imagery. We developed a conceptual basis for the classification of earthworks based on their structural characteristics using fuzzy sets. We recorded 1,279 structures with a distinctive core density zone. Most of the structures displayed geometric shapes, but they varied in construction accuracy. Geoglyphs accounted for 80% of all objects, with geographically variable shapes and enclosure areas. Other earthwork types included associated embankments, solitary embankments and mound sites. The abundance of earthworks provided evidence of strong pre-European human influence on the study area. A 10-km buffer around each earthwork included 75% of recent deforestation areas and 25.7% of standing forest, suggesting a significant potential for the presence of further earthworks in this ancient anthropogenic landscape and its possible far-reaching ecological legacy. The available radiocarbon data confirm a long-term anthropogenic impact in the study area, with ceremonial geoglyphs indicating activities over a thousand years old and other structures revealing more recent cultural transformations.
KEYWORDS:
Acre; anthropogenic landscape; archaeology; geoglyph; mound village; radiocarbon dating
... Si en un primer momento fue la fotografía aérea la que deparó mayores resultados (Rostain, 1994), más tarde se sumaron los sistemas de información geográfica (SIG) y la teledetección (remote sensing) mediante los modelos digitales de elevaciones (MDE) provenientes de proveedores satelitales como la Shuttle Radar Topographic Mission (SRTM) de la NASA, entre otros (de Souza et al., 2018;Heckenberger et al., 2008;Rossetti et al., 2009;Santos et al., 2018;Saunaluoma y Schaan, 2012). Tras ellos, los diversos investigadores también han incluido prospecciones pedestres o campañas de excavación (Iriarte et al., 2021;Prümers, 2017;Saunaluoma, 2012), lo que ha aumentado significativamente el conocimiento en cuanto a formas de subsistencia, rituales funerarios y la cronología de las numerosas construcciones de tierra mediante dataciones radiocarbónicas. ...
... De nuevo frente a otros proyectos, es tal la variedad de formas elementales y tantas las posibilidades de agrupación entre ellas que, por fuerza, alguna puede parecerse a las de otras zonas amazónicas: 11 subtipos de plataformas simples y compuestas, otros 3 de cimas truncadas, 5 tipos de excavaciones lineales, etc. Si los resultados en cuanto a número de estructuras reportadas, kilómetros de caminos, canales y fosos cavados y a variedad tipológica de todo ello es apabullante, también lo es en relación con otros estudios amazónicos similares. Por un lado, en otras investigaciones sobre transformaciones a gran escala de los paisajes prehispánicos de la región apenas se muestran variaciones de los mismos (Lombardo et al., 2011) o en Acre, geoglifos cuadrangulares o circulares, caminos lineales que relacionan los conjuntos e incluso conjuntos circulares formados por montículos irregulares que terminaron siendo de diferente cronología (Iriarte et al., 2021). En consonancia con esta última obra citada, quizá en el valle del Upano no estemos ante funciones distintas, sino ante fenómenos de ocupación diacrónicos: las colinas truncadas identificadas podrían no ser sincrónicas a las plataformas monumentales o podría ser que en ciertas áreas se construyeran las plataformas antes que en otras. ...
Un paisaje monumental prehispánico en la Alta Amazonía ecuatoriana: primeros resultados de la aplicación de Lidar en el valle del Upano Este artículo propone ser la memoria divulgativa y la síntesis de los resultados, muy preliminares, de una primera fase del proyecto Características generales del paisaje cultural arqueológico del valle del Alto Upano en un área de 300 km 2 desarrollado por el Instituto Nacional de Patrimonio Cultural en el año 2015. A nivel metodológico, la principal novedad fue el mapeo sistemático mediante escáner láser aerotransportado (Light Detection and Ranging, Lidar) con fines arqueológicos en un sector de la Alta Amazonía ecuatoriana, ya conocida por los montículos artificiales prehispánicos (400 a. C.-400 d. C.). Se ofrece una imagen general de este tramo del valle del Upano al descubrir asentamientos inéditos hasta entonces, redes de caminería que unían distintos complejos de montículos y una apreciable tipología de plataformas. Los datos obtenidos se relacionan con estudios similares amazónicos con el objetivo de dar cuenta de las semejanzas constructivas y de ofrecer horizontes interpretativos de este singular paisaje prehispánico de la Amazonía ecuatoriana. Finalmente, se proponen líneas de acción futuras para abordar estos datos. arqueología amazónica, patrones de asentamiento, Lidar aerotransportado, montículos de tierra prehispánicos, Ecuador. Amazonian Archaeology, airborne LiDAR, Settlement patterns, pre-Columbian Earthworks, Ecuador. A pre-Columbian monumental landscape in the Ecuadorian Upper Amazon: first results of the application of Li-DAR in the Upano Valley. This article intends to be the informative report and synthesis of the very preliminary results of a first phase of the project General characteristics of the archaeological cultural landscape of the Upper Upano Valley, in an area of 300 km 2 , developed by the National Institute of Cultural Heritage in 2015. At the methodological level, the main novelty was the systematic mapping by airborne laser scanner (Light Detection and Ranging or LiDAR) for archaeological purposes in a sector of the Ecuadorian Upper Amazon, already known for pre-Hispanic artificial mounds (400 BC-400 AD). A general image of this section of the Upano Valley is provided by uncovering previously unpublished mounds assemblages, networks of roads linking different sets, and an appreciable typology of platforms. The data obtained are related to similar Amazonian studies in order to account for the constructive similarities and to offer interpretative horizons of this unique pre-Columbian landscape of the Ecuadorian Amazon. https://revistas.patrimoniocultural.gob.ec/ojs/index.php/Strata/issue/view/4
Recent research has shown that the entire southern rim of Amazonia was inhabited by earth-building societies involving landscape engineering, landscape domestication and likely low-density urbanism during the Late Holocene. However, the scale, timing, and intensity of human settlement in this region remain unknown due to the dearth of archaeological work and the logistical difficulties associated with research in tropical forest environments. A case in point are the newly discovered Mound Villages (AD ~1000–1650) in the SE portion of Acre State, Brazil. Much of recent pioneering work on this new archaeological tradition has mainly focused on the excavation of single mounds within sites with little concern for the architectural layout and regional settlement patterns, thus preventing us from understanding how these societies were organised at the regional level. To address these shortcomings, we carried out the first Lidar survey with a RIEGL VUX-1 UAV Lidar sensor integrated into an MD 500 helicopter. Our novel results documented distinctive architectural features of Circular Mound Villages such as the presence of ranked, paired, cardinally oriented, sunken roads interconnecting villages, the occurrence of a diversity of mound shapes within sites, as well as the exposure the superimposition of villages. Site size distribution analysis showed no apparent signs of settlement hierarchy. At the same time, it revealed that some small groups of villages positioned along streams exhibit regular distances of 2.5–3 km and 5–6 km between sites. Our data show that after the cessation of Geoglyph construction (~AD 950), this region of SW Amazonia was not abandoned, but occupied by a flourishing regional system of Mound Villages. The results continue to call into question traditional views that portray interfluvial areas and the western sector of Amazonia as sparsely inhabited. A brief discussion of our findings in the context with pre-Columbian settlement patterns across other regions of Amazonia is conducted.
Investigations of chronology play a key role in the majority of archaeological research endeavors and are particularly pertinent to examinations of culture-environment relationships, especially during periods characterized by rapid and marked climatic variability and environmental reorganization. Rigorous evaluations of available data and robust methods are required if one wishes to reconstruct reliable chronologies, and this is especially the case when examining periods that are associated with a relatively few radiometric measurements. Such is the case for the Upper Paleolithic archaeological record documented in present-day France from 32,000 to 21,000 calibrated years BP. We take into account critically examined radiocarbon measurements from contextually secure archaeological contexts and employ a recently-developed method of Hierarchical Bayesian Modeling to reconstruct the chronology of archaeological cultures from the Middle Gravettian to the Badegoulian. The calculated chronological intervals for each typo-technologically defined culture phase are compared to the Greenland ice core climatic record and a terrestrial paleoenvironmental record from Bergsee Lake (Southern Germany)—itself expressed in calendar years calculated with the same calibration curve employed in our age model—thereby permitting each archaeological culture to be correlated accurately with documented paleoclimatic variability.
We propose a robust event date model to estimate the date of a target event by a combination of individual dates obtained from archaeological artifacts assumed to be contemporaneous. These dates are affected by errors of different types: laboratory and calibration curve errors, irreducible errors related to contaminations, and taphonomic disturbances, hence the possible presence of outliers. Modeling based on a hierarchical Bayesian statistical approach provides a simple way to automatically penalize outlying data without having to remove them from the dataset. Prior information on individual irreducible errors is introduced using a uniform shrinkage density with minimal assumptions about Bayesian parameters. We show that the event date model is more robust than models implemented in BCal or OxCal, although it generally yields less precise credibility intervals. The model is extended in the case of stratigraphic sequences that involve several events with temporal order constraints (relative dating), or with duration, hiatus constraints. Calculations are based on Markov chain Monte Carlo (MCMC) numerical techniques and can be performed using ChronoModel software which is freeware, open source and cross-platform. Features of the software are presented in Vibet et al. (ChronoModel v1.5 user's manual, 2016). We finally compare our prior on event dates implemented in the ChronoModel with the prior in BCal and OxCal which involves supplementary parameters defined as boundaries to phases or sequences. © 2018 The Korean Statistical Society, and Korean International Statistical Society.
The discovery of large geometrical earthworks in interfluvial settings of southern Amazonia has challenged the idea that Pre-Columbian populations were concentrated along the major floodplains. However, a spatial gap in the archaeological record of the Amazon has limited the assessment of the territorial extent of earth-builders. Here, we report the discovery of Pre-Columbian ditched enclosures in the Tapajós headwaters. The results show that an 1800 km stretch of southern Amazonia was occupied by earth-building cultures living in fortified villages ~Cal AD 1250–1500. We model earthwork distribution in this broad region using recorded sites, with environmental and terrain variables as predictors, estimating that earthworks will be found over ~400,000 km2 of southern Amazonia. We conclude that the interfluves and minor tributaries of southern Amazonia sustained high population densities, calling for a re-evaluation of the role of this region for Pre-Columbian cultural developments and environmental impact.
Improvements in our understandings of the timing and nature of millennial-scale climatic variability
combined with improved dating methods and more accurate calibration curves have allowed researchers
to better place archaeological cultures within their paleoenvironmental contexts. Since all human cultures
operate within an environmental framework, these developments allow researchers to investigate whether
and how cultural variability is related to temporal shifts in culture-environment relationships. Studying
such relationships, however, is dependent on our ability to construct robust chronologies, and this need has
been met by incorporating Bayesian modeling methods into archaeological investigations. This article
reviews the assumptions and methods behind this practice and argues that, while site-specific age models
are useful, we should also employ methods with which chronological models for broad archaeological
cultures can be constructed. Such a combination approach allows one to incorporate available chronological
data thoroughly and to build reliable chronologies that are critical to investigations aimed at
examining culture-environment relationships.
Los Llanos de Mojos han recibido una atención privilegiada en la historia de la
arqueología amazónica boliviana. Las primeras investigaciones se vieron
plasmadas en escritos ya a inicios del siglo pasado. Con el tiempo se reconoció la
complejidad y el potencial arqueológico de la región, dando paso al
emprendimiento de varios proyectos arqueológicos. Cien años después, es tiempo
considerable para evaluar los esfuerzos y alcances de las investigaciones
arqueológicas, no sólo para saber cuánto sabemos, sino y especialmente para
darnos cuenta de lo que todavía nos queda por investigar. El presente artículo
analiza críticamente los aportes de las investigaciones de los últimos años y brinda
nuevos datos para algunas áreas de los Llanos de Mojos.
Significance
The discovery of extensive geometric earthworks beneath apparently pristine rainforest across southern Amazonia has fueled debate over the scale of environmental impact caused by ancient human societies. Whereas some claim that these sites are evidence of vast deforestation by populous pre-Columbian (pre-A.D. 1492) societies, others propose a model of small-scale, localized clearance. We tested these contrasting hypotheses by reconstructing environmental change in a region of geometric earthworks in northeast Bolivia over the last 6,000 y. Our unexpected findings reveal a surprising third scenario, in which earthwork builders took advantage of a naturally open savanna landscape, which existed under drier-than-present climatic conditions before ∼2,000 y ago. This finding suggests lower environmental impact, less labor, and possibly a smaller population than previously assumed.
This article offers a challenge to previous interpretations of the ring villages of Central Brazil. Specifically, these large villages that were occupied by ceramic-making agriculturalists have been characterized as marginal and anomalous developments resulting from late population movements triggered by the European conquest. New data presented here show that the ring villages have a much greater time depth. Their sudden appearance around A. D. 800 is explained as a local response to both regional and external pressures. Information on settlement pattern variables such as village layout and size, differences in cultural inventory, and comparison of archaeological and ethnographic data illustrate sociopolitical and demographic changes through time that have critical implications for Amazonian archaeology.
The archaeology of pre-Columbian polities in the Amazon River basin forces a reconsideration of early urbanism and long-term
change in tropical forest landscapes. We describe settlement and land-use patterns of complex societies on the eve of European
contact (after 1492) in the Upper Xingu region of the Brazilian Amazon. These societies were organized in articulated clusters,
representing small independent polities, within a regional peer polity. These patterns constitute a “galactic” form of prehistoric
urbanism, sharing features with small-scale urban polities in other areas. Understanding long-term change in coupled human-environment
systems relating to these societies has implications for conservation and sustainable development, notably to control ecological
degradation and maintain regional biodiversity.
The long-term response of ancient societies to climate change has been a matter of global debate. Until recently, the lack of integrative studies using archaeological, palaeoecological and palaeoclimatological data prevented an evaluation of the relationship between climate change, distinct subsistence strategies and cultural transformations across the largest rainforest of the world, Amazonia. Here we review the most relevant cultural changes seen in the archaeological record of six different regions within Greater Amazonia during late pre-Columbian times. We compare the chronology of those cultural transitions with high-resolution regional palaeoclimate proxies, showing that, while some societies faced major reorganization during periods of climate change, others were unaffected and even flourished. We propose that societies with intensive, specialized land-use systems were vulnerable to transient climate change. In contrast, land-use systems that relied primarily on polyculture agroforestry, resulting in the formation of enriched forests and fertile Amazonian dark earth in the long term, were more resilient to climate change.
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.
New research in lowland South America is beginning to reveal a diversity of complex cultural trajectories in a region that was long-considered marginal with respect to Andean and Mesoamerican civilizations. This paper summarizes new archaeological, palaeoecological and archaebotanical data from Los Ajos site, south-eastern Uruguay, showing that a changing and increasingly dry mid-Holocene climate was associated with significant cultural transformations, including early village formation, the adoption of a mixed economy and the construction of the earliest public architecture known for the area. Collectively, this evidence indicates an early and unexpected development of social complexity that had not heretofore been recorded in this area of South America. Human-environment interactions, social processes related to the development of early village life and the role of early public architecture are discussed with reference to the emergence of early Formative communities in the region.
The wide availability of precise radiocarbon dates has allowed researchers in a number of disciplines to address chronological questions at a resolution which was not possible 10 or 20 years ago. The use of Bayesian statistics for the analysis of groups of dates is becoming a common way to integrate all of the (14)C evidence together. However, the models most often used make a number of assumptions that may not always be appropriate. In particular, there is an assumption that all of the (14)C measurements are correct in their context and that the original (14)C concentration of the sample is properly represented by the calibration curve. In practice, in any analysis of dates some are usually rejected as obvious outliers. However, there are Bayesian statistical methods which can be used to perform this rejection in a more objective way (Christen 1994b), but these are not often used. This paper discusses the underlying statistics and application of these methods, and extensions of them, as they are implemented in OxCal v 4.1. New methods are presented for the treatment of outliers, where the problems lie principally with the context rather than the (14)C measurement. There is also a full treatment of outlier analysis for samples that are all of the same age, which takes account of the uncertainty in the calibration curve. All of these Bayesian approaches can be used either for outlier detection and rejection or in a model averaging approach where dates most likely to be outliers are downweighted. Another important subject is the consistent treatment of correlated uncertainties between a set of measurements and the calibration curve. This has already been discussed by Jones and Nicholls (2001) in the case of marine reservoir offsets. In this paper, the use of a similar approach for other kinds of correlated offset (such as overall measurement bias or regional offsets in the calibration curve) is discussed and the implementation of these methods in OxCal v 4.0 is presented.
The prevailing view of the Formative in Ecuador is of a period characterized by precocious development and transformation. Initially, the Early Formative (Valdivia) period is marked by a very early appearance of ceramics associated with large U-shaped or circular villages reminiscent of Tropical Forest Culture in the Amazon Basin. Subsequently, through the Valdivia period, these villages assumed an increasingly ceremonial function, while much of the population was dispersed among small settlements scattered along the river valleys. The Early Formative thus apparently witnessed a transformation in settlement, from nucleated villages to a dispersed peasantry surrounding ceremonial centers, and this is characterized as a perhaps seminal, first step in the evolution of the great ceremonial centers of Nuclear America. While the outcome of this evolutionary process in Mesoamerica and the central Andes is well known, it seems to have had little impact in Ecuador: at the end of the Valdivia period, ceremonial activity at the old village sites appears to have ceased, while population seemingly remained dispersed.