The Southern Cone represents the southernmost region of South America settled by humans. Although ancient genomes from southern Patagonia have been sequenced, genomes from the central Southern Cone (CSC) remain temporally and spatially sparse. Archaeology documents major cultural transformations during the Middle and Late Holocene, yet their relationship with demographic processes has been debated. We present genome-wide data from 52 individuals spanning 6,000 years, originating from four regions of the CSC in present-day Argentina and Uruguay: the central and southern Pampas, Northwest Patagonia, the Paraná River Delta and Lower Uruguay River, and the eastern lowlands of Uruguay. Genomic evidence from the Pampas reveals the presence of at least three distinct ancestries during the Middle Holocene. Although genetic contacts with southern Patagonian groups were sporadic, we identified the expansion of an ancestry of unknown geographic origin by 5,500 years ago (ya), which increased during the Late Holocene. This ancestry arrived in Northwest Patagonia by at least 600 ya and co-existed locally with a southern Andean genetic profile until colonial times. Genetic structure differentiates populations along the Paraná River Delta and Lower Uruguay River by 1,500 ya. Individuals from the eastern lowlands of Uruguay show genetic links with Sambaqui-associated populations from the southern coast of Brazil, suggesting the role of human dispersals in connecting tropical lowland cultural traditions. Our work documents the diffusion of genetically distinct groups across all studied regions and provides compelling evidence that large-scale human movements contributed to the remarkable cultural diversity of CSC populations during the Middle and Late Holocene.

Megafauna in South America became extinct by the end of the Late Pleistocene and the relative role of human influence, climate, and other indirect factors in driving these population declines is still a matter of debate. The Campo Laborde archeological site (Pampas, Argentina) offers an exceptional opportunity to understand the complex interactions between climate, ecosystems, and human populations during that time. This study integrates biological proxies (pollen, diatoms, chrysophytes, silicophytoliths) within a stratigraphic framework (sedimentological and geochemical analyses) to reconstruct the paleoenvironmental conditions that prevailed before, during, and after the megamammal hunting and processing event. The results indicate a gradual environmental shift from a stable aquatic environment characterised by greater water availability to a more unstable, shallow and periodically desiccated aquatic environment. Particularly, during the human occupation of the site (similar to 12,600 cal years BP), the shallow and flooded areas acted as attractive zones due to the availability of vital resources such as water, vegetation, and fauna. This environmental evolution was primarily driven by local factors (e.g. topographic setting and hydrological dynamics) and secondarily by regional processes (seasonal precipitation). These results emphasise the importance of paleoecological studies to reconstruct detailed environmental histories at both local and regional scales.

OBJECTIVES:This study explores the subsistence strategies of Middle-to-Late Holocene human populations in the Argentinean Pampas and Paraná River Delta by analyzing dental microwear patterns. MATERIALS AND METHODS:We examined occlusal molar microwear textures of individuals from the Middle and Late Holocene recovered from 12 archaeological sites across three ecologically distinct areas: the Upper Delta of the Paraná River, Central Pampas, and the lower Colorado River Valley. RESULTS:Our results reveal both expected and unexpected trends. Individuals from the resource-rich Upper Delta of the Paraná River exhibited the predicted high dietary diversity (indicated by elevated mean heterogeneity (Hasfc81) values) but also showed surprisingly high mean complexity values (Asfc)-exceeding even those from the two semi-arid areas (Central Pampas and lower Colorado River Valley), where environmental abrasives would have been expected to have resulted in greater microwear texture complexity. DISCUSSION:Within the Paraná Delta, significant intra-site variation at Los Tres Cerros 1 suggests differential food access, possibly tied to social stratification in the Goya-Malabrigo archaeological entity. In the Central Pampas, Middle Holocene individuals from the Arroyo Seco 2 archaeological site displayed greater dietary heterogeneity than contemporaneous and Late Holocene sites, contradicting expectations of progressive diversification during this period. These findings underscore that prehistoric subsistence strategies emerged from complex interactions between ecological constraints and cultural practices, including food processing and social organization.

The main goal of this study is to understand the practices and management of technological production of the hunter-gatherer groups that inhabited the Tapalque creek basin (Olavarria, Buenos Aires). The results of the techno-morphological analysis of the lithic assemblage from the Laguna Blanca Chica site are presented and discussed. Also, the function of a chert accumulation in a shallow lake (possibly a cache or knapping locus) is assessed. The different stages of the operational chains were reconstructed to identify technological practices and recognize the knapping techniques (debitage, fa & ccedil;onnage, and retouch) involved in the production processes of the lithic artifacts. The raw material more frequently used is chert, followed by orthoquartzite with a wide range of colors. In smaller proportions, silica, quartz, silicified dolomite, limestone, and granitoid rocks are also present. Results reveal certain differences in the treatment of the main tool stones, which are reflected in varying technological activities and in the modes of tool manufacture. Finally, the technological practices identified at Laguna Blanca Chica are compared with those from other archaeological contexts within the central Pampa grasslands.

En este trabajo se presentan las principales características tecnológicas del conjunto lítico de Laguna Chica-Sector A. Se propone que a lo largo del Holoceno medio y tardío los grupos que ocuparon este lugar explotaron mayoritariamente rocas de las sierras de Tandilia y, en menor medida, materias primas de otras fuentes localizadas en las subregiones Pampa Húmeda y Seca, así como del sur de San Luis. El conjunto artefactual se compone mayoritariamente de etapas avanzadas de la talla, entre las que se distinguen la producción in situ de una amplia variabilidad de instrumentos y el mantenimiento de filos y núcleos. Los análisis funcionales llevados a cabo sobre instrumentos de ortocuarcita, ftanita y dolomía silicificada permitieron conocer algunas de las tareas realizadas y recursos trabajados (e.g., perforado de piel y raspado de madera). A partir de los resultados alcanzados se plantean estrategias de optimización de las rocas y el equipamiento de lugares.

This paper presents the main technological features of the Laguna Chica-Sector A lithic assemblage. It is proposed that during the middle and late Holocene, the groups that occupied this place mainly exploited rocks from the Tandilia Hills and, to a lesser extent, raw materials from other sources located in the Humid and Dry Pampas sub-regions, and the southern San Luis. The artifactual assemblage is mostly composed of advanced knapping stages, including the in situ production of a wide variety of tools and the maintenance of both edges and cores. Micro-wear analyses carried out on diverse orthoquartzite, chert, and silicified dolomite tools allowed us to identify some of the performed tasks and processed resources (e.g. leather perforation and wood scraping). Based on the results obtained, strategies of raw material optimization and provisioning of places are proposed.

The Southern Cone represents the southernmost region of South America to be colonized by humans. Although ancient genomes have been sequenced from southern Patagonia, genomic data from the central Southern Cone remain temporally and spatially sparse. The archaeological record of this region documents major cultural transformations during the Middle and Late Holocene, yet their relationship to demographic processes has long been debated. Here, we present genome-wide data from 52 individuals spanning the past 5,000 years, originating from four regions of the central Southern Cone in present-day Argentina and Uruguay: the central and southern Pampas, Northwest Patagonia, the Paraná River Delta and Lower Uruguay River, and the eastern lowlands of Uruguay. Genomic evidence from the Pampas reveals the presence of at least three distinct ancestries during the Middle Holocene. While genetic contacts with southern Patagonian groups were sporadic, we identify the expansion of an ancestry of unknown geographic origin by 4,800 years ago, which increased substantially during the Late Holocene. This same ancestry arrived in Northwest Patagonia by at least 600 years ago, and it co-existed with individuals carrying a southern Andean genetic profile until colonial times. Genetic structure differentiates populations along the Paraná River Delta and the Lower Uruguay River by approximately 1,600 years ago. In contrast, individuals from the eastern lowlands of Uruguay show genetic links with Sambaqui-associated populations from the southern coast of Brazil, suggesting the role of human dispersals in connecting tropical lowland cultural traditions. Overall, our work documents the diffusion of genetically distinct groups across all regions studied and provides compelling evidence that large-scale human movements contributed to the remarkable cultural diversity of central Southern Cone populations during the Middle and Late Holocene. ### Competing Interest Statement The authors have declared no competing interest.

The central Southern Cone of South America was one of the last regions of the globe to become inhabited by people1, and remains under-represented in studies of ancient DNA. Here we report genome-wide data from 238 ancient individuals spanning ten millennia. The oldest, from the Pampas region and dating to 10,000 years before present (BP), had distinct genetic affinity to Middle Holocene Southern Cone individuals, showing that differentiation from the central Andes and central east Brazil had begun by this time. Individuals dating to 4,600-150 BP primarily descended from a previously unsampled deep lineage of which the earliest representative is an individual dating to around 8,500 BP. This central Argentina lineage co-existed with two other lineages during the Mid-Holocene and, within central Argentina, this ancestry persisted for thousands of years with little evidence of inter-regional migration. Central Argentina ancestry was involved in three distinct gene flows: it mixed into the Pampas by 3,300 BP and seemingly became the main component there after 800 BP, with central Andes ancestry in northwest Argentina, and with tropical and subtropical forest ancestry in the Gran Chaco. In northwest Argentina, there was an increased rate of close-kin unions by 1,000 BP, paralleling the pattern in the central Andes. In the Paraná River region, a 400 BP individual with a Guaraní archaeological association clusters with Brazilian groups, consistent with Guaraní presence by this time.

This work integrates taphonomic (archaeofaunistics and bioarchaeology) and geoarchaeological (geormorphology, pedologic, sedimentological and micromorphological analyses) information to discuss the depositional and postdepositional history of both surface and buried archaeological record related to past hunter-gatherer populations from the Central Pampean Dunefields of Argentina (South America). Radiocarbon and optically stimulated luminescence dating suggest three temporal clusters of occupations in the Laguna Chica locality: one during the middle Holocene (similar to 8050-6535 years cal. B.P.) and two in the late Holocene (similar to 3350-2870 and similar to 1640-1535 years cal. B.P.). Middle Holocene burials found at the present lake shore are hosted in aeolian sediments that accumulated under arid/semiarid conditions. Modern lacustrine dynamics derived from contraction/expansion cycles have exposed burials, archaeofauna, and stone tools, resulting in displacements, fragmentation and loss. A palimpsest of cultural and natural material spanning similar to 8000 years resulted from this paleoenvironmental setting. Late Holocene human activities might have been related to a transitional landscape, where aeolian processes took place under an expanding lacustrine scenario (i.e., relatively wetter conditions). Our stratigraphic assessment suggests that human occupations were syndepositional agents with episodes of aeolian sand activity and landscape stability. The taphonomic and geoarchaeological evidence from Laguna Chica locality show that the empirical evidence traditionally used to evaluate hunter-gatherer settlement patterns (e.g., abundance and diversity of archaeological evidence and their spatial association in surface or stratigraphic units) and human diet breadth changes (e.g., Ntaxa) may simply reflect the cumulative action of lacustrine erosion of dunes. While both the Laguna Chica surface and stratigraphic records have complex formation histories, the buried context could be interpreted with greater detail through taphonomic and sedimentological analyses.

This paper presents the analysis of chert and orthoquartzite cores recovered from quarry-workshop sites located in the northwestern sector of Tandilia, Buenos Aires province. The main objective is to determine the knapping methods used to reduce the cores and to identify the types of débitage used on each rock. Considering the volumes and morphologies of the cores that were being reduced, the selected technical criteria and production objectives are analyzed. In this sense, different objectives related to obtaining supports represented by modules of different dimensions and thicknesses were identified. In turn, natural and prepared platforms were observed, as well as pieces with unidirectional, bidirectional and multidirectional extractions. There is great variability in the reduction of the cores, some of which are scarcely used and others exhausted, including bipolar pieces. These studies allowed us to recognize different ways in the exploitation of both rocks that are mainly related to the way in which they occur naturally in the outcrops.

OBJECTIVES:Based on the analysis of stable carbon and nitrogen isotopes of bone collagen, stable carbon isotopes of bone apatite and an extensive AMS dating series (~10,000-299 years cal BP), the human paleodiets of 34 individuals from the Central Pampean Dunefields (Argentina, South America) are evaluated. MATERIALS AND METHODS:These data are interpreted from the isotopic ecology of animals with archaeofaunal evidence of consumption and isotopic models of human diet. Multivariate carbon and nitrogen stable isotope model and Bayesian stable isotope ellipses were used to interpret human diets. RESULTS:Analysis of isotopic values indicates intake of enriched lipids and/or carbohydrates in relation to the proteins consumed throughout the Holocene. The isotopic values of Middle Holocene humans in relation to the values of exploited resources point out that individuals obtained protein mainly from guanaco. Subsequently, there was an increase in the human breadth diet during the Late Holocene, with a greater relevance of small prey of high trophic levels and vegetables. This contrasts with zooarchaeological information indicating generalist human diets during the Middle Holocene and specialized human diets in guanaco during the Late Holocene. CONCLUSIONS:It is proposed that during the Middle Holocene arid period, the combination of low human population density and high residential mobility in wide foraging ranges allowed the guanaco to be the main source of protein. During the Late Holocene humid period, there was an increase in human population density and a decrease in residential mobility, which caused greater pressure on foraging territories and increased dietary breadth.

This paper presents the analysis of chert and orthoquartzite cores recovered from quarry- workshop sites located in the northwestern sector of Tandilia, Buenos Aires province. The main goal is to determine the knapping methods used to reduce the cores as well as to identify the d & eacute;bitage (flaking) types used on each rock. Considering the volumes and morphologies of the cores that were reduced, the selected technical criteria and production objectives are analyzed. In this sense, different objectives related to obtaining blanks represented by modules of different dimensions and thicknesses were identified. In turn, natural and prepared platforms were observed, as well as pieces with unidirectional, bidirectional, and multidirectional extractions. There is a great variability in the degree of reduction of the cores, some of which are scarcely used and others exhausted, including bipolar pieces. These studies allowed us to recognize different modes in the exploitation of both rocks that are mainly related to the way in which they occur naturally in the outcrops.

Huencú Nazar was interpreted as a large residential campsite in the Central Pampean Dunefields of Argentina, occupied during several times throughout the Late Holocene (~ 3450 and 2930 years cal BP). Numerous hearths composed of animal bones, caches, and concentrations of lithics, faunal remains, pigments, and charcoals were found. In this context, the production and use of lithic artifacts, and the organization of the space are explored. This was carried out through techno-morphological, use-wear, and spatial analyses of the lithic materials recovered in the different sectors of this site. We identified a non-random organization of the space with sectors where specific well-planned activities were carried out. In a sector close to the body of water, and in relation to three hearths, domestic tasks related to food processing, the manufacture of stone tools, and hide working were identified. This novel information permits to acquire a much better understanding of how the act of working hides was an activity possibly associated with women in one sector of this residential camp. Outside this sector, the manufacture of stone tools by pecking and polishing and woodworking with large orthoquartzite tools were recognized. The presence of site furniture materials (e.g., caches and grinding tools) suggests the presence of long-term occupations and the intention to reoccupy the site in the future.

The lithic raw material sources in the Pampas of Argentina present a very restricted distribution. This has generated various scenarios linked with the acquisition and conveyance of stones carried out by human groups in the past. We explore the mechanisms performed in the procurement, transport and exploitation of rocks by those hunter-gatherer societies that inhabited the Central Pampean Dunefields, an area where lithic resources are absent. The results obtained from five lithic assemblages from the Middle and Late Holocene points to a preference in the exploitation of Tandilia Hills stones through both periods, with an increase in rock diversity in the Late Holocene. Our data indicate a direct procurement of orthoquartzite and chert from Tandilia Hills, although the acquisition of the rest of the raw materials could have involved both direct and indirect procurement. These results may be related to the existence of more fluent exchange networks among Pampas hunter-gatherer groups.

En el sitio arqueológico Laguna de Los Pampas, ubicado en el Campo de Dunas del Centro Pampeano, se han registrado ocho entierros humanos en dos sectores de la playa de la laguna. En este trabajo se analiza este registro mediante distintas líneas de evidencia. Se presentan los resultados alcanzados y se discuten las implicancias de cada uno de ellos para las interpretaciones sobre la dinámica de ocupación del área por parte de los grupos cazadores-recolectores durante el Holoceno. Los resultados indican una ocupación humana durante el Holoceno Temprano y Medio, con una señal más intensa para este último periodo; la modalidad inhumatoria registrada es primaria en todos los casos determinados. Por otro lado, la identificación de modificación tabular oblicua en un individuo del Holoceno Medio (~6000 años AP) constituye un dato novedoso, ya que sería el registro más temprano correspondiente a este tipo deformatorio craneal para la región pampeana. La evidencia analizada sugiere que Laguna de Los Pampas sería producto de la reocupación periódica del lugar a lo largo del tiempo (Holoceno Temprano y Medio), motivada posiblemente por la presencia de rasgos sobresalientes del paisaje, la laguna y los recursos que ella brindaba.

At the Laguna de Los Pampas archaeological site located in the Central Pampean Dunefields, eight human burials have been recorded in two sectors of the shallow lake. In this paper, we analyze this record through different lines of evidence. We present the results obtained and discuss the implications of each for interpreting the occupational dynamics of the area by hunter-gatherer groups during the Holocene. Our results indicate evidence of human occupation during the Early and Middle Holocene, with a stronger presence for the latter period; the recorded burial method is primary in all determined cases. On the other hand, the identification of an oblique tabular modification in one individual from the Middle Holocene (similar to 6000 years BP) represents a novel finding since it would be the earliest record of this type of cranial modification for the Pampas region. The analyzed evidence suggests that Laguna de Los Pampas may be the product of periodic reoccupation of the site over time (Early and Middle Holocene), possibly motivated by the presence of outstanding landscape features, such as the lake and the resources it provided.

The Pampas deer (Ozotoceros bezoarticus) is an endangered ungulate from South American. The following paper presents the first investigation on the isotopic ecology (delta C-13(collagen); delta N-15(collagen)) of modern populations of Pampas deer. The information obtained is compared with new delta C-13 and delta N-15 data of Pampas deer bones recovered from archaeological sites in the Central Pampean Dunefields (Inland Pampa phytogeographic area) and with previously published archeofaunistic isotope data for sites from eastern central Argentina. The range of delta C-13 values of Pampas deer is broad, ranging from a diet dominated by C-3 plants to a mixed diet of C-3 and C-4 plants. The delta N-15 values mainly show distinct signals between the Atlantic coast and the interior. The diet breadth of the Pampas deer suggests a high adaptability to different environments, a crucial factor for conservation programs of this species. The delta C-13 values of the Inland Pampa do not show great differences between the Middle Holocene, Late Holocene and today. Adaptation strategies of the Pampas deer to the environmental changes during the Holocene were not associated with a modification of their feeding habits, but rather with social and demographic strategies. These variations in ecology conditioned the predictability of this prey for hunter-gatherers.

Se presentan los primeros resultados de las investigaciones efectuadas en la localidad arqueológica Laguna Giaccone, localizada en el Campo de Dunas del Centro Pampeano (Buenos Aires, Argentina). Los objetivos son evaluar los aspectos tafonómicos que afectaron el conjunto óseo y determinar las especies animales explotadas, identificar las materias primas líticas, su área de procedencia y las tendencias tecnología desarrolladas sobre cada roca y analizar los aspectos tecno-morfológicos relacionados con la manufactura de la cerámica. Entre los procesos y agentes que más afectaron al conjunto faunístico se encuentran el manganeso, los roedores, el pisoteo y la acción de insectos. Se evidencia que el guanaco, el ñandú y un cormorán/biguá fueron procesados por los grupos cazadores-recolectores. Respecto del material lítico, predominan la ortocuarcita y la ftanita de las sierras de Tandilia y se identificó una amplia diversidad de rocas procedentes de otras fuentes de la región pampeana. Están presentes las últimas etapas de las cadenas operativas y una amplia diversidad de instrumentos. Se registró un alto número de vasijas, algunas confeccionadas mediante la técnica de rollo y cocinadas bajo una atmosfera no oxidante. Las morfologías corresponden a contenedores abiertos y algunos tiestos están decorados. Las distintas líneas de evidencia sugieren que parte de las ocupaciones corresponderían a loci de actividades múltiples desarrolladas durante el Holoceno tardío donde se efectuaron diversas tareas vinculadas con el ámbito doméstico, como el procesamiento y consumo de los recursos animales, la manufactura y uso de instrumentos líticos y la preparación de los alimentos en los recipientes cerámicos.