The transition to agriculture was a transformative process in human history with wide-ranging demographic and social consequences1. Across South America, agriculture was adopted at different times and through diverse pathways, resulting in a mosaic of regionally distinct farming histories2,3. The Uspallata Valley, at the southern frontier of Andean farming, offers a unique opportunity to examine a case of late adoption of agriculture. Here we show that agriculture in the Uspallata Valley was adopted by local hunter-gatherers, as evidenced by genetic continuity between pre-farming and farming populations inferred from 46 newly sequenced ancient human genomes. These groups carried a distinct genetic component in Indigenous American diversity, indicating a unique population history in the region. Palaeodietary isotopes (δ13C/δ15N) reveal fluctuating maize intake consistent with flexible farming. Strontium isotopes (87Sr/86Sr) indicate the arrival of migrants from nearby regions between around 810-700 cal years BP, shortly before the Inka expansion. Genomic and isotopic analyses show that these migrants belonged to the same regional metapopulation as local groups, relied heavily on maize, probably moved in matrilineally organized family groups, exhibited stress markers (including malnutrition and diseases, such as tuberculosis, as confirmed by pathogen genomics) and experienced a long-term demographic decline. Our results suggest that these groups used social organization and migration as resilience strategies in the face of a multidimensional crisis.

Wildfire events are increasingly recognized as agents of taphonomic alteration in archaeological contexts. This study applies causal and statistical modeling to assess the impact of thermal alteration on lithic assemblages in the San Mat & iacute;as Gulf region of Northern Patagonia, Argentina. Utilizing data derived from naturalistic sampling after recent wildfires, we developed a Directed Acyclic Graph (DAG) to identify key mediators and potential confounders affecting lithic fragmentation. A minimal adjustment set was determined to isolate the indirect effect of fire on mechanical alterations, and Random Forest classifiers were trained to evaluate the predictive power of variables such as pebble shape, fissures, and rock type. Comparison between models based on original and synthetically balanced datasets revealed significant improvements in classification accuracy, particularly for unfractured samples. The results emphasize the central role of shape in fracture likelihood, and demonstrate the utility of synthetic resampling and causal inference for interpreting complex taphonomic processes in observational archaeological generalizability of the proposed causal model across fire-affected contexts.

Traditionally, the appearance of the Fell V or "Ona" point in southernmost Patagonia, about 700 BP, was thought to mark the introduction of the bow and arrow. The older and larger Fell IV point was frequently considered a spear point. Here we use data from a previously reported firing experiment with Fell IV replicas to evaluate their possible use as arrowheads. Landmark-based geometric morphometrics describes blade-shape variations along replicas' use-lives, which then are compared with Fell IV and V archaeological points. The main results showed the high performance of Fell IV replicas as arrowheads and the similarity in shape variation among experimental and archaeological points. This suggests a possible earlier introduction of bow and arrow in southernmost Patagonia than commonly assumed, since major innovations in point design would not have been needed in the initial adoption of this technology.

Recent rock art research in the Pali Aike volcanic field (PAVF, southern Argentina and Chile) expanded the chronology (ca. 3100B.P.) and morphological and technical repertoire of abstract-geometric and figurative paintings of the "Rio Chico style". This paper discusses the spatial distribution of painted motifs to understand the criteria that guided the representation strategies and the flow of information among the hunter-gatherers that occupied the PAVF during the late Holocene. By employing social network analysis and statistical tests, two main groups of rock art locations that differ in geographic position, plus the richness and abundance of motifs, were detected. Furthermore, geographical distance was observed to have played a key role in determining the spatial structuring of motif class distribution at the regional level, with significant similarities existing between nearby locations (ca. 20 km) and important differences between more distant ones (ca. 60 km). Thus, rock art paintings as cultural features related to an ancient flow of information and human mobility patterns at a large spatial scale, follow the spatial trend described by other lines of archaeological evidence, which indicates different forms of human land use and occupational intensity between sectors of the PAVF, particularly between the Gallegos (northern sector) and Chico (southern sector) Rivers.

This paper presents a compilation of strontium faunal data from South America (n = 633), which are nearly all from the Andes and Patagonia. In order to build isoscapes of bioavailable strontium, we used machine learning to assess spatial relationships with 46 spatial layers, including a high-resolution 1:5 million geological map. Based on the selected variables, we used predicted 87Sr/86Sr values to make two isoscapes. Isoscape 1 covers the entire study area and is based on three variables: distance to coast, sea salt, and clay percentage; surprisingly, geological age was not a discriminating variable. For Isoscape 2, we focused on a smaller sample from the southern Andes, which meets global expectations that bioavailable strontium correlates with underlying geological age. We compared these isoscapes to human values from two well-studied regions: Mendoza, Argentina, and Moquegua, Peru. In neither case were data sufficient to allow us to adequately geolocate migrants. Toward more robust isoscapes and improved geolocation, we recommend future sampling efforts be built from high-resolution geological maps and consider the potential of smaller but more reliable samples.

This study presents the results of a systematic survey of La Pastosa Islet, located 700 m off the west coast of Río Negro, Argentina. This small islet has the particularity of hosting the northernmost colony of Magellanic penguins ( Spheniscus magellanicus) to date and contains evidence of its use by hunter-gatherer groups during the late Holocene. This growing colony started around 2002 and has had a significant impact on the subsurface archeological record of the islet by increasing erosion and exposing buried materials through nest excavation, particularly lithic artifacts. The spatial analysis of the distribution of artifact and penguin burrows indicates that the actions of the latter generated a “snapshot” of the subsurface distribution of the lithic record. The observed distribution suggested higher discard rates at the center of the islet. Furthermore, this study shows the synergy between both types of records in the formation dynamics of the lithic landscape and the agency of penguins as active landscape engineers. Finally, the obtained results have important implications for the management of the protected sector of the recently established Islote Lobos National Park, within which the study area is located.

The circulation of material culture across space is a central topic in Andean archaeology and has witnessed significant growth during the last decades. Ceramics have been a part of this trend through the analysis of the abundance of chemical elements. Aiming at expanding ceramic sourcing and the study of large-scale conveyance of artefacts, we present the first multi-isotopic approach combining strontium, neodymium, and lead isotopes in South America. We explore the utility of an isoscape of bioavailable strontium for the interpretation of ceramic provenance. These first results show that this approach confidently discriminates large areas of provenance. Broadly, the sherds from styles assigned to the western Andean slope (Llolleo, El Molle, local Inka) show low strontium and lead isotope ratios with high neodymium, consistent with the young ages of underlying rocks, including samples recovered across the Andes and confirming their large-scale conveyance. Conversely, sherds assigned to eastern styles (Agrelo) display high strontium and lead ratios and low neodymium ratios. By exploring the potential of this approach to track ceramic production and conveyance, this research contributes to archaeological debates in the Andes and beyond.

A field-based experiment was carried out to assess the impact of heat on lithic raw materials commonly used for knapping tools along the north Patagonian coast of Argentina. Descriptive data for the experimental items were recorded both before and after exposure to fire. Through network analysis, we explore the relationship between variables to establish the co-occurring of traits resulting from the material's exposure to heat. Statistical analysis of network topology allows us to identify clusters of variables, which were categorized into morphological, mechanical, and pseudo-technological groups. These findings indicate that alterations within the same category covary more than those across different categories. The results obtained are relevant to addressing taphonomic issues in the northern coast of Patagonia, where frequent fire seasons affect surface sites. Ultimately, we aim to characterize these traits and build a reference framework to compare the transformations observed in the lithic archaeological record caused by natural fires.

The Salado and Verde streams constitute the two main seasonally available freshwater courses that flow into the Atlantic coast of the Rio Negro province (continental Patagonia, Argentina, 42 degrees South). This would have favored their use in the past as corridors for human circulation between the coast and the interior. This paper presents the results of the technomorphological and geochemical analyses of the obsidian artifacts recovered in the area to constrain mobility. The results allow us to propose the existence of toolkit reconditioning or replacement activities, and the identification of different sources of provenance of the obsidians (Sacanana, Telsen, and Portada Covunco, distant up to 800 km from the study area), reinforcing the hypothesis of a coast-inland circulation, with the possible existence of circuits of exchange of this raw material.

La colección de materiales arqueológicos “Juan Carlos Piscia”, depositada en manos de su propietario en la ciudad de San Antonio Oeste (Río Negro), está integrada, entre otros ítems, por una amplia muestra de esferas y esferoides líticos recolectados en Saco Viejo y Bajo de la Quinta, dos importantes localidades de la costa rionegrina del golfo San Matías. En este trabajo presentamos el análisis de materias primas, morfológico y morfométrico de la muestra y realizamos una breve comparación con un conjunto arqueológico estudiado previamente por los autores. Los análisis permitieron identificar el uso de materias primas locales para la manufactura de los artefactos, la presencia de ítems con y sin surco (el conjunto de los primeros es más variable que el de los segundos) y una alta inversión de energía puesta en el acabado final de las piezas. El estudio de la colección permitió acceder a información que no estaba disponible previamente por no contar con este tipo de evidencia de manera tan abundante en los sitios arqueológicos. Es por ello que nos interesa rescatar la importancia del estudio complementario de los materiales arqueológicos con los de colecciones, cuando éstas se encuentran disponibles.

Se presentan los resultados de los estudios distribucionales desarrollados en el área circundante al denominado Paredón de los Grabados -extensa barda con petroglifos-, emplazado próximo a las estribaciones de la Sierra Paleimán (provincia de Río Negro) y a 48 km lineales de la costa Atlántica, donde confluyen pequeños cursos de agua estacionarios, tributarios del arroyo Salado. En vista a explorar el uso de este espacio interior se planteó una grilla de muestreo de 1 km de lado, dividida en cuadrantes de 100 m, que fue la base para desarrollar un total de 20 transectas. Los análisis distribucionales volcados en imágenes GIS mostraron una alta densidad del registro arqueológico concentrado principalmente en cañadones y cárcavas asociados a la erosión fluvial. Estos resultados sugieren un uso diferencial del espacio, donde los sectores más altos mostraron bajas densidades y un registro más bien disperso, mientras que se detectó una mayor intensidad de uso de los espacios bajos, próximos al Paredón de los Grabados. Se destaca el predominio de artefactos líticos, y entre los instrumentos el de los raspadores. En cuanto a las materias primas se observó amplia diversidad, incluyendo distintos tipos de obsidiana de procedencia no local. Se registraron también escasos tiestos cerámicos y fragmentos malacológicos marinos (algunos formatizados) indicadores de movilidad o contacto entre áreas, y transporte de un recurso costero. Los resultados obtenidos sugieren que el área fue utilizada de manera redundante a lo largo del tiempo, más factiblemente durante el Holoceno tardío-reciente, y que estaba integrada dentro de las vías de circulación costa-interior.

The "Juan Carlos Piscia" archaeological collection, deposited in the city of San Antonio Oeste (Rio Negro) contains many "bolas" collected in Saco Viejo and Bajo de la Quinta, two important archaeological localities of the San Matias Gulf. In this paper, a raw material, morphological, and morphometric analyses of the sample are presented. A brief comparison is further made with a previously studied archaeological sample. The analyses identified the use of local raw materials for the manufacture of the artifacts, the presence of elements with and without grooves (the former being more variable than the latter), and a high investment of energy in the final finish of the pieces. The study of the collection produced informa- tion not previously available from archaeological studies. Consequently, it is important to highlight that complementary studies of archaeologically recovered materials and those from private collections, when available, should be carried out.

This study is the first exploration of the archaeological record associated with artisanal Octopus fishing along the San Mat & iacute;as Gulf west coast in R & iacute;o Negro province, Argentina, during historical times. The region has been occupied by hunter-gatherer and fishing communities dating back to approximately 3000 BP. Focused on the capture of the small intertidal Octopus species Octopus tehuelchus, this practice involves semi-nomadic small groups that establish temporary settlements along the coastal strip. Initial findings reveal distinctive elements within this archaeological record linked to octopus fishing, offering valuable insights into human spatial utilization, its dynamics with the local environment, and its connections to historical and cultural heritage.

We report the results of distributional studies conducted in the area surrounding the so-called Pared & oacute;n de los Grabados-an extensive wall with petroglyphs- located near the foothills of the Sierra Paleim & aacute;n (province of Rio Negro) and 48 linear kilometers from the Atlantic coast, at the convergence of small seasonal watercourses, tributaries of the Salado creek. To explore the use of this interior space, a sampling grid of 1 km per side, divided into 100 m quadrants, was proposed as the basis for developing a total of 20 transects. The distributional analysis results, presented in GIS images, showed a high density of archaeological records concentrated mainly in gullies and ravines associated with fluvial erosion. These results suggest a differential use of the space, where the higher and rockier sectors, on the other hand, showed low densities and a more dispersed record and a greater intensity of use in lower areas, close to the Pared & oacute;n de los Grabados. A predominance of lithic artifacts, mainly scrapers, is noted. As for raw materials, a wide diversity was observed, including various types of non-local obsidian. There were also a few ceramic shards and marine malacological fragments, some of which were shaped, indicating mobility and contact between areas and the transport of a coastal resource. The results obtained suggest that the area was used redundantly over time, most likely during the late-recent Holocene, and was integrated into the coastal-interior circulation routes.

Several lines of evidence suggest the existence of two hunter-gatherer home ranges in southern Patagonia during the Late Holocene: an eastern one, focused on the Pali Aike volcanic field, and a western one, located along a relatively longitudinal band that goes from the south of the Argentino Lake to ultima Esperanza. While the use of flakes and dacite predominates in the former, blade technology and black shale exploitation is common in the latter. Long-edged stone tools (side-scrapers and knives) on shale blades are also recorded, at low frequency, in the Pali Aike volcanic field and spaces connected to it. Using geometric morphometric techniques, we evaluate whether these tools belong to the same artifact population. Results show no significant morphological differences between the black shale laminar tools according to their discovery area (eastern versus western). Morphological information and other evidence on sizes of laminar tools and availability of black shale, whose main sources are located in the western area, open the discussion on different mechanisms of population interaction involved in the dispersal of these artifacts.

Originally developed for the quantitative analysis of organismal shapes, both two‐dimensional (2D) and 3D geometric morphometric methods (GMMs) have recently gained some prominence in archaeology for the analysis of stone tools—unquestionably the primary deep‐time data source for the earliest periods of human cultural evolution. The key strength of GMM rests in its ability to statistically quantify and hence qualify complex shapes, which in turn can be used to infer social interaction, function, reduction, as well as to assess classification systems and cultural relatedness. The methodological diversification that has accompanied the rise in popularity of this particular suite of methods has, however, also resulted in an increasing lack of comparability and interoperability, which—ironically—works against the promise of GMM to provide a tool for comparing artifact shapes that is not sensitive to interanalyst variation. Standardized protocols, vetted datasets, as well as case‐ transferable and fully reproducible methods do not currently exist, hampering the full utility of geometric morphometrics as an approach to comparatively understand human behavior as reflected in these lithic proxies. Additionally, the emerging issue of methodological diversity in the geometric morphometric analysis of stone tools is further compounded by issues related to landmark selection. When applied to organisms, landmark selection is guided by a priori knowledge about ontogeny, homology, and function. For stone tools, however, only very few such evident landmarks suggest themselves. Instead, many studies have used landmarks selected specifically to highlight particular design features of a given tool class (e.g., stemmed points or leaf points). These cannot, however, be easily compared across tool classes. Other studies have used sets of equidistant landmarks measured perpendicularly from a given tool's longest axis to its margins to describe overall shape. In this context, whole‐outline geometric morphometrics offers an alternative approach that circumvents landmark selection by describing the entire outline of the recorded artifact. It is computationally tractable, readily replicable, and well‐suited for 2D object representations such as drawings and photographs, many of which exist in excavation reports, catalogs, finds registers and the published literature at large. Furthermore, emerging approaches in paleobiology now allow such continuous shape data to be used in phylogenetic applications, opening up the possibility of effectively combining stone tool geometric morphometrics with cultural phylogenetics in one workflow.

In southernmost continental Patagonia (52º S) the introduction of the bow-and-arrow is traditionally associated with the appearance of the small Fell V or "Ona" points around 700 years ago. Earlier and larger Fell IV or "Patagonian" points were considered spear points. Our study focuses on a firing experiment with replicas of the Fell IV points hafted onto arrows that were repeatedly fired and resharpened until the end of their use-life. After each firing, surface impact (bone or meat), macrofractures, and the need for resharpening were recorded. Additionally, size measurements and plan-view photographs of each point at the beginning and end of the experiment, as well as after each resharpening, were documented to further analysis of size and shape variations. Survival-curve models were used to estimate the probability of point survival based on the number of shots and resharpenings endured. By employing landmark-based geometric morphometrics, blade-shape variations throughout replicas' use-life were compared to Fell IV and V archaeological points morphology. The experimental results exhibited the functional efficiency of Fell IV replicas used as arrowheads, with a variable but extended use-life averaging 21 shots and two resharpenings. Shape similarity is observed in the comparison of both experimental and archaeological point datasets. Therefore, an earlier adoption of bow-and-arrow technology in southernmost continental Patagonia is suggested according to experimental data and shape analysis. This technological innovation might be associated with the macroregional climate variations that affected in different ways the subsistence and settlement patterns of Patagonian human populations during the last ca. 2000 years BP.