South-central Andes Research Articles

Evolutionary radiation of mid-Holocene lanceolate points from the highlands of the South Central Andes

Through phylogenetic reconstruction this work  analyzes the  diversification of  lanceolate points of the South Central Andes   which began in the early Holocene and spanned the entire mid- Holocene. Based on a regional-scale data, we   discuss the links between the increasing mid-Holocene risk conditions, the patterns of diversification of point lineages, demographic change and animal resources consumption. We distinguish a first instance of greater diversity of points, a higher rate of innovation and less class longevity. These trends progressively stabilized, giving rise to a pattern of  less innovation, decreasing taxa diversity  and greater class longevity as well as an age-related extinction pattern. We show that as projectile points diversified,hunting efficiency increased along the mid-Holocene by the increased representation of  high-return fauna in the regional zooarchaeological record.  We suggest that this diversification of  lanceolate points was an adaptive evolutionary radiation which began with the increase in the rate of innovation for coping with the increasing risk of the beginning of mid-Holocene in the South Central Andes. From this we conclude that technological innovation was a prerequisite for the human specialization in camelid hunting and for the development of a highly economically efficient foraging strategy in the south Andean  highlands

Semi-supervised contrastive learning for remote sensing: identifying ancient urbanization in the south-central Andes

ABSTRACT Archaeology has long faced fundamental issues of sampling and scalar representation. Traditionally, the local-to-regional-scale views of settlement patterns are produced through systematic pedestrian surveys. Recently, systematic manual survey of satellite and aerial imagery has enabled continuous distributional views of archaeological phenomena at interregional scales. However, such ‘brute force’ manual imagery survey methods are both time- and labour-intensive, as well as prone to inter-observer differences in sensitivity and specificity. The development of self-supervised learning methods (e.g. contrastive learning) offers a scalable learning scheme for locating archaeological features using unlabelled satellite and historical aerial images. However, archaeological features are generally only visible in a very small proportion relative to the landscape, while the modern contrastive-supervised learning approach typically yields an inferior performance on highly imbalanced datasets. In this work, we propose a framework to address this long-tail problem. As opposed to the existing contrastive learning approaches that typically treat the labelled and unlabelled data separately, our proposed method reforms the learning paradigm under a semi-supervised setting in order to fully utilize the precious annotated data (<7% in our setting). Specifically, the highly unbalanced nature of the data is employed as the prior knowledge in order to form pseudo negative pairs by ranking the similarities between unannotated image patches and annotated anchor images. In this study, we used 95,358 unlabelled images and 5,830 labelled images in order to solve the issues associated with detecting ancient buildings from a long-tailed satellite image dataset. From the results, our semi-supervised contrastive learning model achieved a promising testing balanced accuracy of 79.0%, which is a 3.8% improvement as compared to other state-of-the-art approaches.

Provenence and Long-Term Circulation of Archaeological Obsidian in the Puna De Copiapó, South-Central Andes

Provenence and Long-Term Circulation of Archaeological Obsidian in the Puna De Copiapó, South-Central Andes

Chronological sequence (early and late Holocene) and cultural trajectories in Quebrada Pedernales, southern Puna, Chile (26°S-3,456-3,730 masl)

This article presents the results of the interdisciplinary investigation in Quebrada Pedernales (26°S-69°W, Chile 3456 masl), in the highlands of northern Chile. The excavations and surveys carried out revealed a great diversity of pre-Hispanic evidence in an area of the Andes that has been little investigated. This evidence allowed us to reconstruct a sequence of continuous occupation between 11,201–11,612 and 539–634 cal. BP. Zooarchaeological, radiocarbon, technological, geochemical, and carpological analyses suggest wide mobility circuits between the coast and the puna on both slopes of the Andes at the start of the Holocene, coinciding with improved environmental conditions in this area and greater aridity on the coast. A severe lack of human occupation is observed during the mid-Holocene, a phenomenon associated with extreme arid environmental conditions. These trends indicate that the southern limit of influence of this environmental event, which has been recorded in a large part of the south-central Andes, extended into the study area, with a direct impact on the settlement and mobility of human groups. Towards ca. 3000 cal. BP, environmental conditions similar to those of today are associated with the reappearance of archaeological evidence and greater complexity in the formation of settlements, especially in terms of hunting activities.

Crustal focal mechanisms in the NW sierras de cordoba, and connections with mio-pliocene basement thrusting of the easternmost Sierras Pampeanas, south-Central Andes

The seismicity studied in this paper is located along the back arc region, between 30°35′ and 31°52’ S latitude, in the morphostructural unit known as Eastern Sierras Pampeanas. Seventeen crustal earthquakes could be identified and located, between June 2004 and March 2018, using seismic data recorded by the broadband seismological network of National Institute for Seismic Prevention (INPRES), combined with free seismic data from the Incorporated Research Institutions for Seismology (IRIS). Focal mechanisms were calculated from localized seismicity using the P-wave first motions and interpreted as a strain style on the western portion of Sierras de Córdoba. Overall, the seismicity in this region during the study period was constrained to the upper ∼25 km of the crust and is mostly concentrated along minor structures and not along the major range-bounding faults. Although there is evidence of quaternary activity along the larger structures, the relationship between these displacements and modern deformations is not well developed due to the lack of local seismic stations in the area and the long recurrence interval between earthquakes of significant magnitudes. However, very recent morphometric studies in the Sierras Pampeanas have analyzed the main topography controls and suggested relatively higher uplift rates in the central sectors of the Sierra de Pocho, and a balance between tectonic uplift and erosion rates. Nevertheless, three seismic events showed greater depths around 36 km according to previously proposed geological and geophysical models of crustal thickness and mohorovicic depth. Although focal mechanism solutions show varied results, distributed throughout all the region, it is possible to determine an inverse deformation with an oblique component assigned to regional faults and an area where a normal deformation with an oblique component predominates, near to the Ojo de Agua Lineament. Accordingly with seismological observations, we proposed a model in which the seismogenic structures seem to have detached from deep horizontal intra-crustal interfaces that affects the faults and brittle structures, which document that the Eastern Sierras Pampeanas are actively deforming in response to compression from the convergent margin.

Firewood, architecture for fire and society. Agro-pastoralist atmospheres in the Argentine Puna (South Central Andes, ca. 1500 B.P.)

Social circumstances of the use of fire and firewood in past Andean societies are assessed through the anthracological, architectural and contextual analysis of a ritual burning in a foundational event of the agropastoralist societies from the Argentine Puna, at the southernmost part of the high desert of South Central Andes, ca. 1500 B.P. Ethnoarchaeological records on the properties and uses of native bush firewood are alluded to in the interpretation of the context. The composition of the dead bushy mixture was established as made up of 13 plant taxa collected in the vicinity -firewood, and collected in advance far from the place of use -incense plants. Likewise, differences in the composition of the plant mixture were observed when comparing the combustion core and the upper sector of the hearth. An uneven distribution of the soot was recorded, which showed the internal management of firewood and combustion residues. Aromas, smoke, color and light contrasts in the architecture of the combustion structure and the fire itself were defined. From this, a sensory ensemble and a given atmosphere around the fire are defined. They would correspond to household commensality events of the co-resident group which took place during the foundation of the “corral” for the confinement of the Camelidae cattle, and therefore during the foundation of the agro-pastoralist social group itself.

Breeding and global population sizes of the Critically Endangered Red-fronted MacawAra rubrogenysrevisited

SummaryThe ‘Critically Endangered’ Red-fronted Macaw is endemic to seasonally dry, rain-shadowed valleys in the south-central Andes of Bolivia. The remoteness and inaccessibility of most of this region have hampered the rigorous collection of reliable range-wide data on the species’ global, local and breeding population sizes. Such data are imperative, however, for effective conservation and management. Estimated to number up to 5,000 birds in the early 1980s, the most recent and thorough survey to date reported a total of only 807 macaws and a breeding population fraction of about 20% in 2011, disjunctly distributed across eight breeding and six foraging areas and divided into four genetic clusters. Ten years later, we reassessed the species’ population sizes and breeding distribution with increased survey effort and geographic coverage. Six teams simultaneously surveyed different sections of the species’ entire known breeding range in four watersheds focusing on nesting sites. We estimated a global population size of 1,160 macaws, a breeding population fraction of 23.8–27.4% (138–159 nesting pairs) and discovered four new breeding areas. Watersheds and breeding areas differed widely in nesting pair and total macaw numbers. The Mizque watershed held 53% of the species’ breeding and 41.5% of its global population and had the highest breeding population fraction of 30.7–34.9%; the Pilcomayo watershed obtained the lowest values (6%, 8.5% and 14.1–18.2%, respectively). Two of the four documented genetic clusters (subpopulations) each held well over 50 breeding individuals. Two of the eight breeding areas documented in 2011 were found unoccupied in 2021. Numbers of nesting pairs per breeding area in 2011 were poorly correlated with those in 2021, and timing of breeding activities also differed between years. Our new data indicate that the Red-fronted Macaw no longer meets IUCN Red List criteria for ‘Critically Endangered’ species and that it should be downlisted to ‘Endangered.’

Pre-Hispanic anthropogenic wetlands in the upper Ica drainage, south-central Andes: dating and context

Humans have engineered their environments throughout the Holocene, especially in the construction of hydraulic infrastructure. In many regions, however, this infrastructure is difficult to date, including the vestiges of water-management systems in the Andean highlands. Focusing on silt reservoirs in the upper Ica drainage, Peru, the authors use cores and radiocarbon dates to demonstrate the pre-Hispanic construction of walls to enhance and expand wetlands for camelid pasture. Interventions dated to the Inca period (AD 1400–1532) indicate an intensification of investment in hydraulic infrastructure to expand production capacity in support of the state. The results are discussed in the context of the hydraulic strategies of other states and empires.

RETRACTED ARTICLE: Pastoral Paleoclimate Palimpsests of the South-Central Andes: High-Altitude Herder Dwellings in the 2nd Millennium a.d.

ABSTRACT Statement of Retraction: Pastoral Paleoclimate Palimpsests of the South-Central Andes: High-Altitude Herder Dwellings in the 2nd Millennium a.d. We, the Editor[s] and Publisher of Journal of Field Archaeology , have retracted the following article:Sarah I. Baitzel, Martin Polo y La Borda, Bronwen L. Konecky, Jarunetr Sae-Lim and Arturo F. Rivera Infante; Pastoral Paleoclimate Palimpsests of the South-Central Andes: High-Altitude Herder Dwellings in the 2nd Millennium a.d. Journal of Field Archaeology VOL 47, 2022 pages 341-359 DOI: 10.1080/00934690.2022.2072161 Since publication, concerns have been raised about the integrity of the data in the article. When approached for an explanation, the authors checked their data and confirmed there are fundamental errors present. Therefore, they have agreed to the retraction of this article. The authors apologise for this oversight. We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as “Retracted”.

Andean pre-Hispanic pottery forming 3D analysis: a pilot study from Quebrada de Humahuaca (Argentina) using digital methods

Digitization, three-dimensional (3D) documentation and visualization of archaeological materials are processes in increasing development that are used for the enhancement of heritage. These tools have multiple uses for the analysis and research of archaeological objects, although their use in pottery forming techniques studies is less explored. In this paper, diverse digital methods are explored in the study of pottery forming macro-traces, using the 3D model of an archaeological vessel from South-Central Andes. This case is proposed as a pilot study, aiming to reveal the potential of digital techniques for understanding pottery forming techniques. The particular case analysed corresponds to a globular pot of the Humahuaca Black-on-Red style, recovered at the Pucara de Volcán archaeological site, in Quebrada de Humahuaca (Jujuy, Argentina). Initial studies of macro-traces on the pot suggested the use of paddling as the forming technique. The workflow used to contrast this hypothesis included the generation of a 3D model by close-range photogrammetry; and the analysis of the resulting point-cloud and mesh using Morphological Residue Model (MRM) and Virtual Reflectance Transformation Imaging Visualization (V-RTI), with diverse open-source software packages, such as AliceVision Metashape and CloudCompare. These methods increased the micro-topography visibility of the pot surface. As a result, the presence of sub-circular depressions in the body of the pot -similar to percussion cupules-, horizontal pressure lines in the collar, and micro-pull-outs in the maximal diameter of the pot were described. These macro-traces were interpreted as corresponding to the paddling technique used for the elaboration of the pot body —a technique not previously identified in pre-Hispanic traditional pottery manufacturing in the north of Argentina—, and of coiling for manufacturing the collar. The digital methods explored have great potential in the study of pottery forming techniques, although their scope depends on the accuracy of the 3D model analysed.

Technology, life histories and circulation of gold objects during the Middle Period (AD 400–1000): A perspective from the Atacama Desert, Chile

Studies of archaeological goldwork in the Americas are increasingly revealing a rich variety of context-specific ways in which gold items were produced and valued, but research attention has largely focused on visually striking artefacts. However, in the south-central Andes, goldwork is described essentially as a ‘sheet technology’—a definition that tends to downplay the potential complexity and cultural significance of this technology in such an extensive and varied region. Here, we employ a life-history approach to explore the existence of particular traditions within this large area. We present chemical and microscopic analyses, using pXRF, SEM–EDS, PIXE and digital microscopy, of 142 gold and silver objects from San Pedro de Atacama (northern Chile), recovered in seven cemeteries dated to the Middle Period (AD 400–1000). Our results reveal a heterogeneous assemblage where compositions, techniques, designs and skill levels vary, suggesting that gold artefacts circulated and were imported from different areas of the south-central Andes, such as Tiwanaku, Cochabamba and northwest Argentina. We also identify for the first time two distinct technological traditions used in San Pedro: small-scale goldwork production, and a tradition of modifying and reusing imported objects by cutting, perforating and separating object parts. Considering the depositional contexts, we propose that the funerary ritual at San Pedro was a key factor in the development of this local goldwork. Our research demonstrates that even small and unimpressive artefacts can be successfully interrogated from archaeological perspectives with integrative approaches that go beyond overly generalising perspectives of gold as an exotic status marker.

Impact of the Juan Fernandez Ridge on the Pampean Flat Subduction Inferred From Full Waveform Inversion

AbstractA new seismic model for crust and upper mantle of the south Central Andes is derived from full waveform inversion, covering the Pampean flat subduction and adjacent Payenia steep subduction segments. Focused crustal low‐velocity anomalies indicate partial melts in the Payenia segment along the volcanic arc, whereas weaker low‐velocity anomalies covering a wide zone in the Pampean segment are interpreted as remnant partial melts. Thinning and tearing of the flat Nazca slab is inferred from gaps in the slab along the inland projection of the Juan Fernandez Ridge. A high‐velocity anomaly in the mantle below the flat slab is interpreted as relic Nazca slab segment, which indicates an earlier slab break‐off triggered by the buoyancy of the Juan Fernandez Ridge during the flattening process. In Payenia, large‐scale low‐velocity anomalies atop and below the re‐steepened Nazca slab are associated with the re‐opening of the mantle wedge and sub‐slab asthenospheric flow, respectively.

An Early Hispanic-Indigenous Contact Event at the Los Viscos Archaeological Site in the South-Central Andes: A Zooarchaeological Perspective

An Early Hispanic-Indigenous Contact Event at the Los Viscos Archaeological Site in the South-Central Andes: A Zooarchaeological Perspective

Comment on Arnold et al. (2021): CP in the MCA?

The Central Pacific (CP) flavor of El Niño/Southern Oscillation (ENSO) may account for some of the Medieval Climate Anomaly (MCA) aridity in the highland Titicaca Basin of the South Central Andes observed by Arnold et al. (2021 in Quaternary Science Reviews). There is urgent need for a longer record of CP presence and frequency.

Herbivore coprolites from the South-Central Andes. A multiproxy study at Los Viscos Archaeological Site, Catamarca, Argentina

Coprolites are among the faunal traces of the archaeological and paleontological fossil record. This is the first study of multiple proxies in herbivore coprolites from the South-Central Andes. The study includes Late Holocene samples from Los Viscos Archaeological Site in Catamarca, Argentina, of the last 2000 years. The aim of this study was to determine the zoological origin of the coprolites as an additional line of evidence to identify the fauna that entered the site. Pellet morphology, parasite contents, ancient DNA (aDNA) and pollen were analysed. Consistently with other reports of local faunal remains, most samples were determined as from Camelidae and Cetartiodactyla. Capra hircus was also identified close to a c. 400-year-old occupation, suggesting an early presence of this European herbivore in the region. Most of the identified parasite remains were taxon-specific. The identification of Fasciola hepatica eggs in goat coprolites provides early evidence of this parasite in domestic ruminants of the region, possibly from the early Hispanic-Indigenous contact. Regarding the diet items of these herbivores, the pollen spectra in the coprolites provide some clues to their management. These results have also allowed us to pose some palaeoecological hypotheses that will be tested in future research as well as to discuss some methodological implications of this multiproxy approach.

Colors and dyes of archaeological textiles from Tarapac\xe1 in the Atacama Desert (South Central Andes)

This work concerns the study of colors and dyes identified on archaeological textiles from the Atacama Desert. The different garments and ornaments come from the excavation of two important pre-Columbian cemeteries of the Tarapacá region: Tarapacá-40 attributed to the Formative period (1100 BC–660 AD) and Pica-8 to the Late Intermediate period (900–1450 AD). For the first time, a multi-analytical approach with non-invasive techniques using FORS and SERS was applied on samples of less than 2 cm of length for physicochemical characterization of the raw materials and the dyes employed in the textile production of northern Chile. The fibers are from animal origin. Blue, green, and yellow are identified as indigo, but we cannot discard a mixture with other dyes to vary hue and shade; while carminic acid and alizarin—to a lesser extent—are found on red, orange, and brown samples. This research provides new elements for the discussion about the textile technology developed in this desertic region, its changes, and continuities along the history. Our results are compared to recent findings on neighboring regions from South-Central Andes, to improve the current knowledge and discuss the existence of dyeing textile cultural traditions.

Technology, Use and Reuse of Gold during the Middle Period: The Case of Casa Parroquial, Atacama Desert, Chile

The life-histories of gold artefacts can provide rich insight into technology and culture, but so far the potential of this research approach has not been exploited in the south central Andes. Here we present the analysis of 34 gold and silver objects from the Middle Period cemetery of Casa Parroquial (San Pedro de Atacama, northern Chile), using pXRF, SEM-EDS, PIXE and digital microscopy. Chemical analyses detected variable compositions (2.4–73.1 per cent Ag and 0.2–3.4 per cent Cu) suggesting that artisans used both native gold and artificial gold-silver-copper alloys. Based on their manufacturing techniques, quality and designs, we identify two working styles, one technically more ‘careful’ than the other. Given their elemental and technological variety, together with the lack of local production evidence, we propose that these artefacts were imported as finished objects from Tiwanaku or Cochabamba and northwest Argentina. However, we identify a series of objects that were modified or reshaped as they entered a new cultural context, revealing complex life-histories. Modifications used relatively simple mechanical means: punching, cutting and folding, most likely made in multi-craft contexts by non-metallurgists from San Pedro.

Late Intermediate Period Funerary Traditions, Population Aggregation, and the Ayllu in the Sihuas Valley, Peru

The Late Intermediate period in the south-central Andes is known for the widespread use of open sepulchres called chullpas by descent-based ayllus to claim rights to resources and express idealized notions of how society should be organized. Chullpas, however, were rarer on the coast, with the dead often buried individually in closed tombs. This article documents conditions under which these closed tombs were used at the site of Quilcapampa on the coastal plain of southern Peru, allowing an exploration into the ways that funerary traditions were employed to both reflect and generate community affiliation, ideals about sociopolitical organization, and land rights. After a long hiatus, the site was reoccupied and quickly expanded through local population aggregation and highland migrations. An ayllu organization that made ancestral claims to specific resources was poorly suited to these conditions, and the site's inhabitants instead seem to have organized themselves around the ruins of Quilcapampa's earlier occupation. In describing what happened in Quilcapampa, we highlight the need for a better understanding of the myriad ways that Andean peoples used mortuary customs to structure the lives of the living during a period of population movements and climate change.

Guanaco hunting and Llama herding in the South-Central Andes (3000-900 BP): An osteomorphometrical approach

This paper aims to contribute to the study of the subsistence of human populations from the northern part of the Quebrada de Humahuaca (Northwestern Argentina –NWA-) between 3000 and 900 years BP, through the morphological and morphometric analysis of bone remains from large-sized camelids. The contribution of two complementary strategies -guanaco (Lama guanicoe) hunting and llama (Lama glama) herding- to the diet of those populations throughout the late Holocene is assessed. In order to achieve this, the first and second anterior and posterior phalanges are analyzed through both traditional morphometric (TM) and two-dimensional geometric morphometric (2D GMM) techniques. The sample is composed of 398 elements from 49 modern llamas and guanacos, and 36 elements from archaeological camelids recovered from the Antumpa, Cóndor II and Casas Grandes sites. We discuss the problem of the taxonomic identification of South American large-sized camelids with a novel methodology and we contribute relevant zooarchaeological information for a poorly studied geographical setting. Results indicate that llama herding prevailed throughout the late Holocene (4000-300 AP), although TM techniques showed a slight increase in guanaco hunting during the final late Holocene (1100-300 BP) and GMM showed a constant frequency of representation. The trends and variations thus identified would respond to both anthropic and local ecological factors.

Indigenous Routes and Resource Materialities in the Early Spanish Colonial World: Comparative Archaeological Approaches

The early colonial period witnessed new scales of connectivity and unprecedented projects of resource extraction across the Spanish Americas. Yet such transformations also drew heavily on preexisting Indigenous landscapes, technologies, and institutions. Drawing together recent discussions in archaeology and geography about mobility and resource materialities, this article takes the early colonial route as a central object of investigation and contributes to new emerging interpretive frameworks that make sense of Spanish colonialism in the Americas as a variable, large-scale, and materially constituted process. Using three case studies—theruta de Colónon the island of Hispaniola, the routes connecting the southeastern Caribbean islands with mainland South America, and theruta de la platain the south-central Andes—we develop a comparative archaeological analysis that reveals divergent trajectories of persistence, appropriation, and erasure in the region's routes and regimes of extraction and mobility during the fifteenth and sixteenth centuries.