Simulating the effects of kinship and postmarital residence patterns on mitochondrial DNA diversity in mortuary contexts.

OBJECTIVES: We explore the observable outcome in mtDNA diversity of different kinship systems and associated postmarital residence patterns in the archeological record, using simulations at the intrapopulation level. MATERIALS AND METHODS: Four kinship systems were simulated from a set of variable fertility and mortality scenarios. Initial conditions consisted of six clusters of variable size and a random number of assigned haplotypes, with individuals migrating between groups and reproducing for 15 generations. Each 15-generation span was simulated 500 times to obtain representative intrasite mtDNA diversity distributions for each kinship system. Additional simulations were devised to consider the effect of migration and different rates of adherence to kinship norms. RESULTS: Matrilineal kinship generates low male and female haplotype diversities that are statistically indistinguishable from each other, while female diversity in bilateral kinship with matrilocality is significantly lower than that observed in male diversity. Furthermore, mtDNA diversity generated by patrilineal kinship is very high. The effect of noncompliance with kinship rules is low; migration has a considerable impact on diversity, eventually obscuring the effect of kinship practices. DISCUSSION: The results of the simulations can be applied to ancient mtDNA data from archeological contexts, as exemplified with data from two studies. On a broader scale, the kinship system followed by the sampled population, can lead to either over- or underestimation of mtDNA population diversity. The results of the simulations can be used in the design of inferential frameworks to discern kinship scenarios in the archeological record, based on mtDNA and other types of evidence.

Climate change and long-term human behaviour in the Neotropics: an archaeological view from the Global South.

In this paper, we argue for the inclusion of archaeology in discussions about how humans have contributed to and dealt with climate change, especially in the long term. We suggest Niche Construction Theory as a suitable framework to that end. In order to take into account both human and environmental variability, we also advocate for a situated perspective that includes the Global South as a source of knowledge production, and the Neotropics as a relevant case study to consider. To illustrate this, we review the mid-Holocene Hypsithermal period in the southern Puna and continental Patagonia, both in southern South America, by assessing the challenges posed by this climate period and the archaeological signatures of the time from a Niche Construction Theory perspective. Finally, we emphasize the importance of these considerations for policymaking. This article is part of the theme issue 'Climate change adaptation needs a science of culture'.

Predicting the geographic distribution of ancient Amazonian archaeological sites with machine learning.

Amazonia has as least two major centers of ancient human social complexity, but the full geographic extents of these centers remain uncertain. Across the southern rim of Amazonia, over 1,000 earthwork sites comprised of fortified settlements, mound villages, and ditched enclosures with geometric designs known as geoglyphs have been discovered. Qualitatively distinct and densely located along the lower stretches of major river systems and the Atlantic coast are Amazonian Dark Earth sites (ADEs) with deep anthropogenic soils enriched by long-term human habitation. Models predicting the geographic extents of earthworks and ADEs can assist in their discovery and preservation and help answer questions about the full degree of indigenous landscape modifications across Amazonia. We classify earthworks versus ADEs versus other non-earthwork/non-ADE archaeological sites with multi-class machine learning algorithms using soils, climate, and distances to rivers of different types and sizes as geospatial predictors. Model testing is done with spatial cross-validation, and the best model at the optimal spatial scale of 1 km has an Area Under the Curve of 0.91. Our predictive model has led to the discovery of 13 new geoglyphs, and it pinpoints specific areas with high probabilities of undiscovered archaeological sites that are currently hidden by rainforests. The limited, albeit impressive, predicted extents of earthworks and ADEs means that other non-ADE/non-earthwork sites are expected to predominate most of Western and Northern Amazonia.

Stable isotope data and radiocarbon dates from Brazilian bioarchaeological samples: An extensive compilation.

Three decades have passed since the publication in 1991 of the first use of stable isotope analysis applied to a Brazilian archaeological context. Despite being still mainly applied to palaeodietary research, stable isotope analysis in archaeology has been diversified in Brazil. In the last five years, an increasing number of studies has addressed various issues. Such issues are related to population mobility, social differentiation, health and children care, changes and resilience of cultural practices, and identification of the origin of enslaved populations brought by force from the African continent, among others. However, research in this area is still incipient when compared to the large territory of Brazil (WGS 84: -33˚ to 5°N, -73˚ to -34˚E), the diversity of socio-cultural contexts of pre-colonial and indigenous societies, and the country's historical formation process. In terms of radiocarbon dates, data are also sparse and lack essential information as the material used for dating, as this information could be related to necessary corrections, e.g., the marine reservoir effect. The first radiocarbon dates of Brazilian archaeological material are reported, however, since the 1950s and have been more frequently reported in publications across Brazil since the installation of the first Brazilian radiocarbon laboratory (CENA/USP) in 1990 and the first Latin American 14C-AMS facility (LAC-UFF) in 2012. Thus, the purpose of this compilation was to gather all dispersed, and often fragmented, data from analyses of stable and radioactive (focusing on radiocarbon) isotopes carried out in Brazilian archaeological contexts. We compiled data from 1991 until the end of November 2021. The data included here contain information from 71 archaeological sites, 556 humans, 219 animals and 2 plants. Isotopic analyses were performed on 832 organic samples, mainly paired δ13C and δ15N plus δ34S measurements, and on 265 mineral samples, mainly δ13C, δ18O and 86Sr/87Sr measurements. Sr concentrations for 49 mineral samples were also compiled. Radiocarbon or relative dates span from 18 kyr BP to the present. All data from this compilation are deposited in open access on the IsoArcH platform (https://doi.isoarch.eu/doi/2021.005). This extensive work aims to point out the gaps in stable isotopes and radiocarbon dates provided for Brazilian archaeological contexts that could be further explored. Besides, it aims to promote easy access to numerous analyses that, otherwise, would be hard to obtain. Lastly, it seeks to broaden the interdisciplinary collaboration in Brazil and strengthen the international collaboration among peers.

Potential distributions of pre-Columbian people in Tropical Andean landscapes.

Much has yet to be learned of the spatial patterning of pre-Columbian people across the Tropical Andes. Using compiled archaeological data and a suite of environmental variables, we generate an ensemble species distribution model (SDM) that incorporates general additive models, random forest models and Maxent models to reconstruct spatial patterns of pre-Columbian people that inhabited the Tropical Andes east of the continental divide, within the modern countries of Bolivia, Peru and Ecuador. Within this region, here referred to as the eastern Andean flank, elevation, mean annual cloud frequency, distance to rivers and precipitation of the driest quarter are the environmental variables most closely related to human occupancy. Our model indicates that 11.04% of our study area (65 368 km2) was likely occupied by pre-Columbian people. Our model shows that 30 of 351 forest inventory plots, which are used to generate ecological understanding of Andean ecosystems, were likely occupied in the pre-Columbian period. In previously occupied sites, successional trajectories may still be shaping forest dynamics, and those forests may still be recovering from the ecological legacy of pre-Columbian impacts. Our ensemble SDM links palaeo- and neo-ecology and can also be used to guide both future archaeological and ecological studies. This article is part of the theme issue 'Tropical forests in the deep human past'.

Heritage and the Archaeology of Afro-Peru: Community Engagement in the Valleys of Nasca.

The year 2019 marked the quadricentenary of two communities in the Ingenio Valley of Nasca, Peru, founded as vineyard haciendas by the Society of Jesus (Jesuits). For a decade, the Haciendas of Nasca Archaeological Project (PAHN) has carried out archaeological and ethnohistorical research in collaboration and consultation with valley communities descended from the haciendas' enslaved populations. PAHN was envisioned as a project aimed at engaging Peruvian publics at multiple scales. PAHN engages local descendant communities in an exploration of their history through historical archaeology, as well as a broader public-entering national conversations about the visibility of African descendants and their histories in Peru. Through our varied approaches to the archaeology of slavery and hacienda as cultural heritage through in-person engagement and our Web initiatives during the international pandemic of 2020, we consider the importance of maintaining engagement with multiple publics when normal activities are disrupted.

El año 2019 marcó el cuadricentenario de dos comunidades en el Valle del Ingenio de Nasca, Perú, fundadas como haciendas de viñedos por la Compañía de Jesús (Jesuitas). Durante una década, el Proyecto Arqueológico Haciendas de Nasca (PAHN) ha realizado investigaciones arqueológicas y etnohistóricas en colaboración y consulta con las comunidades del valle descendientes de las poblaciones esclavizadas de las haciendas. El PAHN se concibió como un proyecto destinado a involucrar al público peruano en múltiples escalas. El PAHN involucra a las comunidades de descendientes locales en una exploración de su historia a través de la arqueología histórica, así como a un público más amplio, entrando en conversaciones nacionales sobre la visibilidad de los descendientes de africanos y sus historias en el Perú. A través de nuestros variados enfoques de la arqueología de la esclavitud y la hacienda como patrimonio cultural a través del compromiso presencial y nuestras iniciativas web durante la pandemia internacional de 2020, consideramos la importancia de mantener el compromiso con múltiples públicos cuando se interrumpen las actividades normales.

L'année 2019 a marqué le quadricentenaire de deux communautés de la vallée Ingenio de Nasca, au Pérou, fondées en tant qu'haciendas vinicoles par la Société de Jésus (Jésuites). Pendant une décennie, le Projet archéologique des Haciendas de Nasca (PAHN) a mené une recherche archéologique et ethno-historique en collaboration et en consultation avec des communautés de la vallée issues par leur descendance des populations d'esclaves des haciendas. Le PAHN a été envisagé comme un projet destiné à mobiliser les populations péruviennes à des niveaux multiples. Le PAHN fait participer les communautés descendantes locales à une exploration de leur histoire dans le cadre d'une archéologie historique, ainsi qu'un public plus vaste permettant l'accès aux conversations nationales sur la visibilité des descendants africains et de leurs histoires au Pérou. Grâce à nos approches variées de l'archéologie de l'esclavage et de l'hacienda en tant que patrimoine culturel et par le biais d'une participation en personne et de nos initiatives sur le Web durant la pandémie internationale de 2020, nous examinons l'importance qu'il y a à préserver la mobilisation de publics multiples lorsque les activités normales sont interrompues.

La epidemiología, discurso y saber / Analysis of health systems as political systems

A partir de la segunda mitad del siglo XX, la dimensión del lenguaje y la palabra fue tomando un lugar central en las reflexiones filosóficas y políticas en diversos ámbitos (tanto en Europa como en América del norte y del sur). Entre ellos, en el campo de la medicina, tanto en su ejercicio clínico como en sus derivaciones de orden social: el campo de la salud pública, las intervenciones epidemiológicas, comunitarias, etc. Surgió una crítica a la hegemonía del pensamiento científico. Frente a eso, diversas propuestas desde otros campos del saberse fueron incorporando al debate en el campo teórico, y en el político. Un debate entre la ciencia y sus aplicaciones frente a otras perspectivas de saber. Eso dio lugar a diversas prácticas conocidas bajo diversos nombres: medicina social, nueva salud pública, anti psiquiatría, etc. (parte del desarrollo creciente del psicoanálisis se inscribe en este conjunto), todas ellas críticas con la hegemonía indiscutible hasta ese momento del positivismo científico, que se postulaba como el único saber válido .La perspectiva iniciada por Foucault, luego seguida por muchos otros pensadores e investigadores, abrió un cuestionamiento de esa hegemonía de las ciencias y una valoración de otras perspectivas de saber, no científicas, pero con una validez que se imponía en las prácticas sociales .El campo del saber, investigado mediante lo que denominó "arqueología del saber" analiza esa dialéctica, mediante la producción de una serie de teorías y conceptos precisos: discurso, enunciado, archivo, entre otros. Ciencia y saber aparecen entonces como prácticas diferenciadas, en una relación compleja y plena de controversias fundamentales. A todo ello se agrega la "genealogía del poder", una dimensión del poder y la política profundamente imbricada con el campo del saber, que permitió que los análisis de las prácticas se conmovieran y renovaran de forma radical. La propuesta foucaultiana concluye indagando en las posibilidades de lo que llama "saberes sometidos" de no ceder ante las explicaciones universalistas -propias de la ciencia-para dar cuenta de los procesos humanos. Propugna entonces un desarrollo de los discursos críticos, que frente a los saberes eruditos -propios de la ciencia y sus instituciones-puedan sostener la emergencia de un "saber histórico de las luchas".

Since the second half of the 20th century, the dimension of language and the word has been taking a central place in philosophical and political reflections in various fields (both in Europe and in North and South America). Among them, in the field of medicine, both in its clinical practice and in its social derivations: the field of public health, epidemiological and community interventions, etc. A criticism arose against the hegemony of scientific thought. In response to this, various proposals from other fields of knowledge were incorporated into the debate in the theoretical and political fields. A debate between science and its applications versus other perspectives of knowledge. This gave rise to various practices known under different names: social medicine, new public health, anti-psychiatry, etc. (part of the growing development of psychoanalysis is inscribed in this group), all of them critical of the undisputed hegemony up to that time of scientific positivism, which was postulated as the only valid knowledge.The perspective initiated by Foucault, then followed by many other thinkers and researchers, opened a questioning of this hegemony of the sciences and a valuation of other perspectives of knowledge, non-scientific, but with a validity that was imposed on social practices.The field of knowledge, investigated through what he called "archeology of knowledge", analyzes this dialectic through the production of a series of theories and precise concepts: discourse, enunciation, archive, among others. Science and knowledge appear then as differentiated practices, in a complex relationship full of fundamental controversies.To all this is added the "genealogy of power", a dimension of power and politics deeply intertwined with the field of knowledge, which allowed the analysis of practices to be radically moved and renewed.Foucault's proposal concludes with an inquiry into the possibilities of what he calls "subjected knowledges" of not yielding to universalist explanations -proper of science-in order to account for human processes. He then advocates a development of critical discourses, which, in the face of erudite knowledge ­proper to science and its institutions-can sustain the emergence of a "historical knowledge of struggles".

The First Cathedral on America's Pacific Coast.

New research dispels the idea that Panamá Viejo was initially founded one-half mile from the site of its visible present-day ruins. The archaeological and historical evidence, subjected to interdisciplinary analysis, demonstrates that the city remained on the same main plaza next to its natural port from its founding 500 years ago until its destruction in 1671. The data reconsidered and newly uncovered also suggest reasons for previous misinterpretations of the city's early foundational history. Unlike many colonial cities and towns, Panamá Viejo did not move during its first century of existence. However, its main church, which became the bishopric's cathedral in 1524, did relocate after 1541. The new evidence establishes and confirms the original location of the first cathedral on America's Pacific Ocean to the south of Panamá Viejo's main plaza and explains its move to an elevated, rocky area on the eastern side of the same plaza over 20 years later. Excavations undertaken in 2018 have confirmed the original building's location a mere 50 m from the visible ruins of the cathedral, the tower of which remains a symbol of Panamanian identity today.

Las nuevas investigaciones despejan la idea de que Panamá Viejo fue inicialmente fundada a milla y media del sitio en donde ahora son visibles sus ruinas. Las evidencias arqueológicas e históricas, sometidas a un análisis interdisciplinar, demuestran que la ciudad permaneció en el mismo emplazamiento, al lado de su puerto natural, fundada 500 años atrás hasta su destrucción en 1671. La revisión de la información disponible, además de la descubierta recientemente, también sugieren las razones de los errores interpretativos previos en torno a la historia fundacional de la ciudad. A diferencia de numerosas ciudades y pueblos coloniales, Panamá Viejo no fue trasladada durante su primer siglo de existencia. Sin embargo, su iglesia principal, la cual se convirtió en sede catedralicia en 1524, fue reubicada después de 1541. La nueva evidencia confirma la localización original de la primera catedral en el Pacífico americano al sur de la plaza mayor de Panamá Viejo y explica el traslado a un área rocosa más elevada, en el costado este de esta plaza, unos veinte años más tarde. Las excavaciones adelantadas en el 2018 han confirmado su ubicación original a escasos 50 m de las actuales ruinas de la catedral, cuya torre permanece como un símbolo de la identidad panameña hoy.

Une nouvelle recherche écarte l'idée que la fondation de Panama Viejo soit intervenue originellement à 800 m du site de ses ruines visibles de nos jours. Les preuves historiques et archéologiques, lorsqu'elles sont assujetties à une analyse interdisciplinaire, démontrent que la ville est demeurée sur la même place principale que son port naturel à compter de sa fondation il y a 500 ans jusqu'à sa destruction en 1671. Les données ayant fait l'objet d'un nouvel examen et qui ont été découvertes suggèrent également les motifs à l'appui des interprétations erronées de l'histoire de la fondation initiale de la ville. Contrairement à de nombreuses villes et cités coloniales, Panama Viejo ne s'est pas déplacée au cours du premier siècle de son existence. Cependant, son église principale qui est devenue en 1524 la cathédrale de l'évêché, s'est implantée ailleurs après 1541. Les preuves nouvelles établissent et confirment le site originel de la première cathédrale sur l'Océan pacifique de l'Amérique au sud de la place principale de Panama Viejo et expliquent son déplacement vers une zone élevée, rocheuse sur la partie orientale de la même place plus de 20 ans par la suite. Les fouilles entreprises en 2018 ont confirmé le site de la bâtisse d'origine à seulement 50 m des ruines visibles de la cathédrale, dont la tour demeure un symbole de l'identité panaméenne de nos jours.

Reassessing the role of climate change in the Tupi expansion (South America, 5000-500 BP).

The expansion of forest farmers across tropical lowland South America during the Late Holocene has long been connected to climate change. The more humid conditions established during the Late Holocene are assumed to have driven the expansion of forests, which would have facilitated the dispersal of cultures that practised agroforestry. The Tupi, a language family of widespread distribution in South America, occupies a central place in the debate. Not only are they one of the largest families in the continent, but their expansion from an Amazonian homeland has long been hypothesized to have followed forested environments wherever they settled. Here, we assess that hypothesis using a simulation approach. We employ equation-based and cellular automaton models, simulating demic-diffusion processes under two different scenarios: a null model in which all land cells can be equally settled, and an alternative model in which non-forested cells cannot be settled or delay the expansion. We show that including land cover as a constraint to movement results in a better approximation of the Tupi expansion as reconstructed by archaeology and linguistics.

Breastfeeding and weaning in Late Holocene hunter-gatherers of the lower Paraná wetland, South America.

OBJECTIVE: In this study, we analyze breastfeeding and weaning practices in pre-Columbian complex hunter-gatherers from the lower Paraná River basin (South America). MATERIALS AND METHODS: We carried out bone isotope analyses concerning δ13 C in collagen and apatite, the spacing between both carbon sources and δ15 N in a sample of 23 subadult and adult individuals of both sexes recovered from Late Holocene archaeological sites, ranging from 1665 ± 45 to 680 ± 80 14 C years BP. RESULTS AND DISCUSSION: The results indicate that exclusive breastfeeding continued until the age of ~2 years, and weaning probably until 4 years of age. Supplementary foods included C3 plants and probably animal fats and C4 carbohydrates. A high fractionation of 4.9‰ in δ15 N values was recognized between breastfeeding infants and adult females, perhaps reflecting episodic hyper-protein diets in women linked to men's food provisioning during women's gestational/postpartum period. Additionally, male adults present a higher protein intake than females. Although this difference is not statistically significant with the current sample size, it could be a clue related to a sexual division in food procurement.

Deep classification of cut-marks on bones from Arroyo del Vizcaíno (Uruguay).

The earliest widely accepted presence of humans in America dates to approximately 17.5 cal kyr BP, at the end of the Last Glacial Maximum (LGM). Among other evidence, this presence is attested by stone tools and associated cut-marks and other bone surface modifications (BSM), interpreted as the result of the consumption of animals by humans. Claims of an older human presence in the continent have been made based on the proposed anthropogenic modification of faunal remains; however, these have been controversial due to the highly subjective nature of the interpretations. Here, we employ advanced deep learning algorithms to objectively increase the accuracy of BSM identification on bones. With several models that exhibit BSM classification accuracies greater than 94%, we use ensemble learning techniques to robustly classify a selected sample of BSM from the approximately 30 kyr BP site of Arroyo del Vizcaíno, Uruguay. Our results confidently show the presence of cut-marks imparted by stone tools on bones at the site. This result supports an earlier presence of humans in the American continent, expanding additional genetic and archaeological evidence of a human LGM and pre-LGM presence in the continent.

Population history of Brazilian south and southeast shellmound builders inferred through dental morphology.

OBJECTIVE: The Southeast and South Coast of Brazil was inhabited during most of the Holocene by shellmound builders. Although there are cultural differences in the archaeological record between regions, it is still debatable how these differences may relate to different population histories. Here, we contribute to this discussion by exploring dental morphological affinities between several regional series. MATERIALS AND METHODS: Dental morphology of 385 individuals from 14 archaeological sites was analyzed using the Arizona State University Dental Anthropology System. Fifteen traits were used to explore morphological affinities among series through Euclidean distance, Mean Measure of Divergence, and Principal Component Analysis. Mantel matrix correlation and partial correlation tests were used to examine the association between biological, geographic, and chronological distances. RESULTS: Morphological affinities show that ceramic and nonceramic South Coast groups cluster and differ from most Southeast series. In contrast, Southeast coastal and riverine groups display high morphological variance, showing less biological coherence among them. These biological distances between regions are partially explained by geography, but not by chronology. CONCLUSIONS: The results support that these coastal populations were low-mobility groups. Although interactions between individuals of different regions likely existed, gene flow occurred mostly among individuals from local or adjacent areas. The introduction of ceramic in the South Coast is not associated with changes in dental morphology patterns, suggesting its adoption is not exclusively associated with the arrival of different biological groups. Southeast coastal and riverine groups show high phenotypic diversity, suggesting a different history of human occupation and cultural development than observed in the South Coast.

Archaeogenomic distinctiveness of the Isthmo-Colombian area.

The recently enriched genomic history of Indigenous groups in the Americas is still meager concerning continental Central America. Here, we report ten pre-Hispanic (plus two early colonial) genomes and 84 genome-wide profiles from seven groups presently living in Panama. Our analyses reveal that pre-Hispanic demographic events contributed to the extensive genetic structure currently seen in the area, which is also characterized by a distinctive Isthmo-Colombian Indigenous component. This component drives these populations on a specific variability axis and derives from the local admixture of different ancestries of northern North American origin(s). Two of these ancestries were differentially associated to Pleistocene Indigenous groups that also moved into South America, leaving heterogenous genetic footprints. An additional Pleistocene ancestry was brought by a still unsampled population of the Isthmus (UPopI) that remained restricted to the Isthmian area, expanded locally during the early Holocene, and left genomic traces up to the present day.

Notas sobre los factores naturales y culturales en el desarrollo sociopolítico prehispánico en el extremo noroeste de Guanacaste, Costa Rica / Notes on natural and cultural factors in the pre-Hispanic sociopolitical development of the northwest of Guanacaste, Costa Rica

Introducción: El estudio interdisciplinario de los patrones de ocupación y desarrollo de la sociedad humana en tiempos prehispánicos es tenue en la zona del volcán Orosí. El contexto ambiental es usualmente descrito para ilustrar patrones de subsistencia, sin mayor propósito de establecer formas de relación con los cambios que se vislumbran en la composición sociopolítica de los pobladores. Objetivo: En este trabajo, se explora la posibilidad de ilustrar instancias de relación entre los cambios que detecta el registro arqueológico, con potenciales factores naturales y culturales, según se destacan en los aportes de otras disciplinas científicas. Métodos: Una muestra de 111 componentes culturales identificados en sitios arqueológicos fue examinada en cuanto a su localización geográfica en diversos ecosistemas y su posición cronológica, respecto de los períodos culturales definidos en la región de Guanacaste. Resultados: Los componentes arqueológicos se confrontan con diversos factores naturales y culturales que habría incidido como agentes de cambio. Se analizaron las instancias de relación y se valoraron sus efectos por períodos, cubriendo tiempos precerámicos y cerámicos. Conclusiones: Se identifica como agentes naturales de cambio a la calidad de suelos, el tipo de clima, pero, ante todo, destacan los procesos culturales como el intercambio de productos, desarrollo de la agricultura y los movimientos migratorios de la población.

Introduction: Interdisciplinary studies on ancient occupation patterns and the development of human society in the Orosí Volcano region are few. Environmental data are included in archaeological studies of specific sites, mainly to illustrate the likely availability of local subsistence resources, with little regard for biodiversity linked to altitude and an array of different geomorphic areas. Effects surging from volcanic activity and tectonics are largely dispensed. Incidence of all these natural phenomena is rarely considered as agents of sociopolitical changes. Objective: Herein a search is performed in order to detect and illustrate instances of the relationship between sociopolitical change detected by archaeology and diverse natural and cultural factors as described by other scientific disciplines. Methods: A sample of 111 cultural components in archaeological sites were examined in terms of their geographical location, ecological context and chronological position along the periods of the cultural sequence in the Guanacaste region. Results: As settlement models, the archaeological data are confronted with diverse natural and cultural factors looking for their potential incidence as agents for sociopolitical change. Instances of relationship are examined and their apparent effects are evaluated for each period, both in preceramic and ceramic times. Conclusions: Both soil quality and climate are identified as important factors for change and development. Yet, largely salient are distinct cultural factors, namely the exchange of products, agriculture and migration processes.

Did pre-Columbian populations of the Amazonian biome reach carrying capacity during the Late Holocene?

The increasingly better-known archaeological record of the Amazon basin, the Orinoco basin and the Guianas both questions the long-standing premise of a pristine tropical rainforest environment and also provides evidence for major biome-scale cultural and technological transitions prior to European colonization. Associated changes in pre-Columbian human population size and density, however, are poorly known and often estimated on the basis of unreliable assumptions and guesswork. Drawing on recent developments in the aggregate analysis of large radiocarbon databases, here we present and examine different proxies for relative population change between 1050 BC and AD 1500 within this broad region. By using a robust model testing approach, our analyses document that the growth of pre-Columbian human population over the 1700 years prior to European colonization adheres to a logistic model of demographic growth. This suggests that, at an aggregate level, these pre-Columbian populations had potentially reached carrying capacity (however high) before the onset of European colonization. Our analyses also demonstrate that this aggregate scenario shows considerable variability when projected geographically, highlighting significant gaps in archaeological knowledge yet also providing important insights into the resilience of past human food procurement strategies. By offering a new understanding of biome-wide pre-Columbian demographic trends based on empirical evidence, our analysis hopes to unfetter novel perspectives on demic expansions, language diversification trajectories and subsistence intensification processes in the Amazonian biome during the late Holocene. This article is part of the theme issue 'Cross-disciplinary approaches to prehistoric demography'.

The Surco canal, an ancient irrigation canal in Lima, Peru, and a citizens' campaign for its protection.

The present text discusses a number of pre-Hispanic irrigation canals in Lima, the Peruvian capital, often considered as the second largest city built on a desert. Some of the original canals are still in use but given that most have been excluded from official urban narratives, citizens are not aware of them and the role they still play in the city. A brief description of Lima's canals through the ages is provided, including present day management and the risks affecting them. This paper focuses on the Surco canal and a citizens' campaign carried out between 2016 and 2018 to raise awareness about it. The impact the campaign has had on the wider city is discussed. A general overview of the cultural context in which pre-Hispanic issues have historically been considered in Lima and how this campaign also tried to address them is included as well. As this paper is part of a special issue, Water History in the time of COVID-19, it has undergone modified peer review.

El Niño resilience farming on the north coast of Peru.

El Niño-Southern Oscillation has been treated as a disruptor of environmental and socioeconomic equilibrium both in ancient times and in modern-day Peru. Recent work in the coastal desert plain, known as the Pampa de Mocan, challenges this view by demonstrating that prehispanic irrigation systems were designed to incorporate floods and convert them into productive waters. Archaeological investigations in this landscape reveal a 2,000-y history of floodwater farming embedded in conventional canal systems. Together with a pollen record recovered from a prehispanic well, these data suggest that the Pampa de Mocan was a flexible landscape, capable of taking advantage of El Niño floodwaters as well as river water. In sharp contrast to modern-day flood mitigation efforts, ancient farmers used floodwaters to develop otherwise marginal landscapes, such as the Pampa de Mocan, which in turn mitigated risk during El Niño years. These archaeological data speak to contemporary policy debates in the face of increasingly intense and frequent natural disasters and question whether El Niño Southern Oscillation events should be approached as a form of temporary disorder or as a form of periodic abundance.