Papers by Daniel Contreras
Seeking Synchronicity: Re-examining the Peruvian Early Horizon through Bayesian Modeling of 14C Dates
Senri Ethnological Studies, 2023
This paper presents the results of Bayesian bounded phase models of published 14C dates associate... more This paper presents the results of Bayesian bounded phase models of published 14C dates associated with phases linked to the “Early” or “Chavín” horizon from seven sites spread over a wide area of the Central Andes. The results suggest that these phases have a high probability of being contemporary and of relatively short duration (<300 years, and in the better-dated cases <200 years), and thus argue that Andeanist archaeologists should revisit the possibility of a specific and widespread period of heightened regional interaction in the 1st millennium BCE. Although attention to local trajectories and attempts at nuanced explanation of single-site or single-valley dynamics have largely supplanted previous interest in regional patterns during this period, this new chronology suggests that it is time to revive this brief period of heightened interaction in the region as a subject of research, and work to develop research strategies with sufficient chronological resolution to address questions about regional dynamics.
the Holocene, 2022
South American arid lands present unique constellations of climatic risk to their human inhabitan... more South American arid lands present unique constellations of climatic risk to their human inhabitants, due to volatile events that can create markedly different hydroclimate conditions over interannual–centennial scales. However, a main driver of such volatility – the El Niño/Southern Oscillation (ENSO) – occurs with semiregular periodicity. Paleoclimatic and archeological evidence indicate not only that the strength and periodicity of ENSO patterns have changed over the late-Holocene, but their impacts were likely recognized, adapted to, and perhaps capitalized upon by agriculturalists employing adaptive risk strategies. We examine relationships over the last 1.3 kyr between ENSO periodicity, ecological transitions, and archeological settlement in Peru’s Chicama Valley through a coupled paleohydroclimate and agroecology model. We reconstruct periods when ENSO-like conditions dominated past hydroclimates and present a quantitative, spatially-explicit analysis of ecological productivity during modern ENSO-positive hydroclimate conditions. We show that archeological settlement patterns are sensitive to these transformations and reflect efforts to capitalize on expanded agroecological niches. Such expanded niches potentially offset the adverse impacts and risks associated with abrupt ENSO climate events. These results suggest archeological communities were aware of ENSO risk and managed productive strategies accordingly, highlighting the importance of a risk calculus that considers the net ecological effects of climate events.
Sustainability, 2022
Human beings are an active component of every terrestrial ecosystem on Earth. Although our local ... more Human beings are an active component of every terrestrial ecosystem on Earth. Although our local impact on the evolution of these ecosystems has been undeniable and extensively documented, it remains unclear precisely how our activities are altering them, in part because ecosystems are dynamic systems structured by complex, non-linear feedback processes and cascading effects. We argue that it is only by studying human-environment interactions over timescales that greatly exceed the lifespan of any individual human (i.e. the deep past or longue durée), can we hope to fully understand such processes and their implications. In this article we identify some of the key challenges faced in integrating long-term datasets with those of other areas of sustainability science, and suggest some useful ways forward. Specifically, we a) highlight the potential of the historical sciences for sustainability science, b) stress the need to integrate theoretical frameworks wherein humans are seen as inherently entangled with the environment, and c) propose formal computational modelling as the ideal platform to overcome the challenges of transdisciplinary work across large, and multiple, geographical and temporal scales. Our goal is to provide a manifesto for an integrated scientific approach to the study of socio-ecological systems over the long term.
Antiquity, 2022
Common assumptions about the ephemeral archaeological signature of pastoralist settlements have l... more Common assumptions about the ephemeral archaeological signature of pastoralist settlements have limited the application of geophysical techniques in the investigation of past herding societies. Here, the authors present a geophysical survey of Luxmanda, Tanzania, the largest-known settlement documented for the Pastoral Neolithic era in eastern Africa (c. 5000-1200 BP). The results demonstrate the value and potential of fluxgate gradiometry for the identification of magnetic anomalies relating to archaeological features, at a category of site where evidence for habitation was long thought to be undetectable. The study provides comparative data to enable archaeologists to identify loci for future investigations of mobile populations in eastern Africa and elsewhere.
Stages, Periods, and Radiocarbon: 14C Dating in the Archaeology of the Central Andes
Ñawpa Pacha, 2022
Some of the earliest archaeological materials radiocarbon-dated were from the Central Andes, and ... more Some of the earliest archaeological materials radiocarbon-dated were from the Central Andes, and archaeologists from the region were also involved in early efforts at meta-analysis of assemblages of radiocarbon dates and Bayesian chronological modeling. Nevertheless, regional chronological schema still vary surprisingly little from their pre-radiocarbon antecedents. As a result, significant scope for increasing the impact of radiocarbon dates, as well as making their use more robust and transparent, remains. Improved use of radiocarbon dates has the potential to reconfigure Central Andean chronologies, suiting them better to addressing many of the questions that archaeologists wish to ask. With this in mind, I here review the history of use of 14C dating in the archaeology of the Central Andes, before focusing on practical issues that confront archaeologists working in the region as they both employ 14C dates and seek to be informed and critical consumers of published 14C dates and chronologies.
Algunas de las primeras muestras que se entregaron para fechar con radiocarbono vinieron de los Andes Centrales, y la región también ha liderado en los esfuerzos de meta-análisis de agrupaciones de fechados de radiocarbono y de modelaje cronológico bayesiano. Sin embargo, es bastante común encontrar en uso esquemas cronológicos que varían muy poco con respeto a sus antecedentes pre-radiocarbono. Aquí planteo que eso se debe no solo al costo y a los detalles científicos del método, que pueden ser desalentadores, sino también a un legado de escepticismo. Como resultado, existe ámbito amplio para hacer más robusto y transparente el uso de los fechados 14C, y también para aumentar su impacto. Aún más de medio ciclo después de su introducción, el uso de radiocarbono todavía tiene el potencial de reconfigurar las cronologías centroandinas, haciéndolas más apropiadas para contestar las preguntas que se formulan los arqueólogos. Pensando en ese potencial, aquí reviso la historia del uso del método radiocarbónico en la arqueología de los Andes Centrales. Después pongo el foco en los asuntos prácticos que se enfrentan los arqueólogos que trabajan en la región: calibración, reservorio marino, articulación de fechados 14C entre si y con sus contextos arqueológicos, y el meta-análisis de compilaciones de fechados radiocarbónicos. Estos asuntos son importantes tanto para los arqueólogos que utilizan fechados 14C como para los que aspiran a ser consumidores informados y críticos de los fechados 14C publicados y las cronologías basadas en ellas.
A new Minoan-type peak sanctuary on Stelida, Naxos
Journal of Greek Archaeology, 2021
Journal of Arid Environments, 2022
El Niño Southern Oscillation (ENSO) is a periodic disruption of tropical Pacific oceanic/atmosphe... more El Niño Southern Oscillation (ENSO) is a periodic disruption of tropical Pacific oceanic/atmospheric conditions, which changes global precipitation regimes. One area strongly affected by positive (el Niño) phases is South America’s Pacific Coast. The specific effects of ENSO on Andean ecological communities have received little attention, however. We examine vegetation gross primary productivity (GPP) on Peru’s north coast arid-lands during a recent (2016 - 2017) el Niño, using a time series of Sentinel 2 imagery. By comparing GPP time-series in endemic desert vegetation communities to agricultural subregions, we demonstrate that arid-land productivity during ENSO-positive phases can meet or exceed agricultural thresholds. These results are the first to quantify and spatialize GPP between ENSO-neutral and ENSO-positive phases for South American arid-lands. They outline the scale of the el Niño effects on terrestrial ecosystems and highlight the resulting opportunities for human inhabitants. The dramatic changes to endemic vegetation on the normally hyperarid coastal desert of Peru suggest that periodic el Niño precipitation plays a critical role in arid land ecodynamics. These findings improve our understanding of ENSO’s net effects, highlight the roles of abrupt climate events in the arid land ecology of NW South America, and can inform human responses to these events.
Matching Pragmatic Lithic Analysis and Proper Data Architecture: The QuARI R Shiny Database Interface
Advances in Archaeological Practice, 2021
The documentation and analysis of archaeological lithics must navigate a basic tension between ex... more The documentation and analysis of archaeological lithics must navigate a basic tension between examining and recording data on individual artifacts or on aggregates of artifacts. This poses a challenge both for artifact processing and for database construction. We present here an R Shiny solution that enables lithic analysts to enter data for both individual artifacts and aggregates of artifacts while maintaining a robust yet flexible data structure. This takes the form of a browser-based database interface that uses R to query existing data and transform new data as necessary so that users entering data of varying resolutions still produce data structured around individual artifacts. We demonstrate the function and efficacy of this tool (termed the Queryable Artifact Recording Interface [QuARI]) using the example of the Stelida Naxos Archaeological Project (SNAP), which, focused on a Paleolithic and Mesolithic chert quarry, has necessarily confronted challenges of processing and analyzing large quantities of lithic material.
Earliest occupation of the Central Aegean (Naxos), Greece: Implications for hominin and Homo sapiens’ behavior and dispersals
Science Advances , 2019
We present evidence of Middle Pleistocene activity in the central Aegean Basin at the chert extra... more We present evidence of Middle Pleistocene activity in the central Aegean Basin at the chert extraction and reduction complex of Stelida (Naxos, Greece). Luminescence dating places ~9000 artifacts in a stratigraphic sequence from ~13 to 200 thousand years ago (ka ago). These artifacts include Mousterian products, which arguably provide first evidence for Neanderthals in the region. This dated material attests to a much earlier history of regional exploration than previously believed, opening the possibility of alternative routes into Southeast Europe from Anatolia (and Africa) for (i) hominins, potentially during sea level lowstands (e.g., Marine Isotope Stage 8) permitting terrestrial crossings across the Aegean, and (ii) Homo sapiens of the Early Upper Paleolithic (Aurignacian), conceivably by sea.
Science Advances, 2019
We present evidence of Middle Pleistocene activity in the central Aegean Basin at the chert extra... more We present evidence of Middle Pleistocene activity in the central Aegean Basin at the chert extraction and reduction complex of Stelida (Naxos, Greece). Luminescence dating places ~9000 artifacts in a stratigraphic sequence from ~13 to 200 thousand years ago (ka ago). These artifacts include Mousterian products, which arguably provide first evidence for Neanderthals in the region. This dated material attests to a much earlier history of regional exploration than previously believed, opening the possibility of alternative routes into Southeast Europe from Anatolia (and Africa) for (i) hominins, potentially during sea level lowstands (e.g., Marine Isotope Stage 8) permitting terrestrial crossings across the Aegean, and (ii) Homo sapiens of the Early Upper Paleolithic (Aurignacian), conceivably by sea.
Hacia una geoarqueología del paisaje andino: paisaje, medioambiente y acción humana en Chavín de Huántar
Lugares, Monumentos, Ancestros. Arqueologías de Paisajes Andinos y Lejanos, 2018
Public Archaeology's Mammoth in the Room: Engaging Wikipedia as a Tool for Teaching and Outreach
Advances in Archaeological Practice, 2019
Although archaeology has become increasingly concerned with engaging diverse publics, and has emb... more Although archaeology has become increasingly concerned with engaging diverse publics, and has embraced the internet as a means of facilitating such engagement, attitudes towards Wikipedia have—understandably—been more ambivalent. Nevertheless, we argue here, Wikipedia's popularity and reach mean that archaeologists should actively engage with the website by adding and improving archaeological content. One way to do this is in the classroom: this paper provides a detailed how-to for instructors interested in having students create new Wikipedia content. We provide a case study in Wikipedia engagement from an advanced undergraduate course on African Archaeology, assess a program (Wiki Education) designed to help, and suggest further avenues for future outreach. We conclude that Wikipedia's utopian mission aligns with many of the goals of public archaeology, and argue that archaeology has much to gain by engaging with—rather than ignoring or even shunning—Wikipedia.
Proceedings of the Complex Systems Academy of Excellence, 2018
Complexity theory provides useful concepts for archaeological issues related to the understanding... more Complexity theory provides useful concepts for archaeological issues related to the understanding of past societies and their environment. More specifically, Agent-Based Modelling is a relevant tool to explore scenarios and to test hypotheses about the impacts of complex socioenvironmental interactions on the transformations of ancient settlement systems evident in archaeological records. After a short historiography of complex systems modelling in Archaeology, this paper focus on the mains issues of archaeological simulation models. As a case study, we briefly present the model under development within the ModelAnSet project supported by UCAJEDI Complex Systems Academy of Excellence. Agent-Based Modelling is used to explore the respective impacts of environmental and social factors on the settlement pattern and dynamics during the Roman period in South-Eastern France.
PLOS ONE, 2018
Holocene climate variability in the Mediterranean Basin is often cited as a potential driver of s... more Holocene climate variability in the Mediterranean Basin is often cited as a potential driver of societal change, but the mechanisms of this putative influence are generally little explored. In this paper we integrate two tools–agro-ecosystem modeling of potential agricultural yields and spatial analysis of archaeological settlement pattern data–in order to examine the human consequences of past climatic changes. Focusing on a case study in Provence (France), we adapt an agro-ecosystem model to the modeling of potential agricultural productivity during the Holocene. Calibrating this model for past crops and agricultural practices and using a downscaling approach to produce high spatiotemporal resolution paleoclimate data from a Mediterranean Holocene climate reconstruction, we estimate realistic potential agricultural yields under past climatic conditions. These serve as the basis for spatial analysis of archaeological settlement patterns, in which we examine the changing relationship over time between agricultural productivity and settlement location. Using potential agricultural productivity (PAgP) as a measure of the human consequences of climate changes, we focus on the relative magnitudes of 1) climate-driven shifts in PAgP and 2) the potential increases in productivity realizable through agricultural intensification. Together these offer a means of assessing the scale and mechanisms of the vulnerability and resilience of Holocene inhabitants of Provence to climate change. Our results suggest that settlement patterns were closely tied to PAgP throughout most of the Holocene, with the notable exception of the period from the Middle Bronze Age through the Early Iron Age. This pattern does not appear to be linked to any climatically-driven changes in PAgP, and conversely the most salient changes in PAgP during the Holocene cannot be clearly linked to any changes in settlement pattern. We argue that this constitutes evidence that vulnerability and resilience to climate change are strongly dependent on societal variables.
For several decades, researchers have sought to defin~ a rel~tions~t between environmental change... more For several decades, researchers have sought to defin~ a rel~tions~t between environmental change and initial human expe:lmentatlon Wit food production in southwest Asia. Many ~odels emphas~ze t?e r~le of ~he Younger Dryas, a Northern Hemisphere-wide cold and an~ cl!mat~c 'per~~~ that lasted from approximately 12,900 B.P.-ll,~OO .B.P . .' In providing . impetus for first human experimentation with cultl~atlon In southwest As~a.
From paleoclimate variables to prehistoric agriculture: Using a process-based agro-ecosystem model to simulate the impacts of Holocene climate change on potential agricultural productivity in Provence, France
Quaternary International, 2018
This paper explores the relationship between past climate and prehistoric Mediterranean agricultu... more This paper explores the relationship between past climate and prehistoric Mediterranean agriculture by adapting a process-based dynamic vegetation model to estimate potential agricultural productivity under climate scenarios that characterize the extremes of Mediterranean climate in the Holocene. We adapt LPJmL (the Lund-Potsdam-Jena-managed-land model [Bondeau et al., 2007]), a process-based dynamic vegetation model, to the modeling of potential agricultural productivity in the past. Calibrating this model for past crops and agricultural practices and using a downscaling approach to produce high spatiotemporal resolution paleoclimate data, we produce quantitative estimates of potential yields under past climatic conditions derived from four Holocene climatic extremes (warm/wet, warm/dry, cold/wet, and cold/dry) under two different assumptions (approximate high and low limits) about the intensity of agricultural practice. We here discuss this process with reference to a case study in Provence, examining the methodology and data requirements for modeling past agriculture using LPJmL and considering the implications of the range of variability in potential agricultural productivity under distinct climate conditions. We focus particularly on comparing the range of variability induced by climatic shifts with that achievable through changes in agricultural practices as a means of approaching questions of past vulnerability and resilience.
Reaching the human scale: A spatial and temporal downscaling approach to the archaeological implications of paleoclimate data
Journal of Archaeological Science, 2018
Assessing the implications of paleoclimatic and paleoenvironmental data at temporal and spatial s... more Assessing the implications of paleoclimatic and paleoenvironmental data at temporal and spatial scales that would have directly intersected with human decision-making and activity is a fundamental archaeological challenge. This paper addresses this challenge by presenting a spatial and temporal downscaling method that can provide quantitative high-spatio-temporal-resolution estimates of the local consequences of climatic change. Using a case study in Provence (France) we demonstrate that a centennial-scale Mediterranean-wide model of Holocene climate, in conjunction with modern geospatial and climate data, can be used to generate explicit and solidly-grounded monthly estimates of temperature, precipitation, and cloudiness at landscape scales and with annual resolution, enabling consideration of climate variability at human scales and meeting the data requirements of socioecological models focused on human activity. While the results are not reconstructions – that is, particular values are single realizations, consistent with the coarse-grained data but not individually empirically derived nor unique solutions – they provide a more suitable basis for assessing the human consequences of climate change than can coarse-grained data.
Journal of Field Archaeology, 2018
The later Holocene spread of pastoralism throughout eastern Africa profoundly changed socioeconom... more The later Holocene spread of pastoralism throughout eastern Africa profoundly changed socioeconomic and natural landscapes. During the Pastoral Neolithic (ca. 5000–1200 B.P.), herders spread through southern Kenya and northern Tanzania — areas previously occupied only by huntergatherers — eventually developing the specialized forms of pastoralism that remain vital in this region today. Research on ancient pastoralism has been primarily restricted to rockshelters and special purpose sites. This paper presents results of surveys and excavations at Luxmanda, an openair habitation site located farther south in Tanzania, and occupied many centuries earlier, than previously expected based upon prior models for the spread of herding. Technological and subsistence patterns demonstrate ties to northerly sites, suggesting that Luxmanda formed part of a network of early herders. The site is thus unlikely to stand alone, and further surveys are recommended to better understand the spread of herding into the region, and ultimately to southern Africa.
Stélida is a major source of chert, a siliceous raw material that was exploited for the manufactu... more Stélida is a major source of chert, a siliceous raw material that was exploited for the manufacture of flaked stone tools from the Lower Paleolithic to the Mesolithic (≥250,000–9,000 B.P.). This paper reviews the work of the 2013-16 seasons.
Rituals of the Past: Prehispanic and Colonial Case Studies in Andean Archaeology , 2017
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Papers by Daniel Contreras
Algunas de las primeras muestras que se entregaron para fechar con radiocarbono vinieron de los Andes Centrales, y la región también ha liderado en los esfuerzos de meta-análisis de agrupaciones de fechados de radiocarbono y de modelaje cronológico bayesiano. Sin embargo, es bastante común encontrar en uso esquemas cronológicos que varían muy poco con respeto a sus antecedentes pre-radiocarbono. Aquí planteo que eso se debe no solo al costo y a los detalles científicos del método, que pueden ser desalentadores, sino también a un legado de escepticismo. Como resultado, existe ámbito amplio para hacer más robusto y transparente el uso de los fechados 14C, y también para aumentar su impacto. Aún más de medio ciclo después de su introducción, el uso de radiocarbono todavía tiene el potencial de reconfigurar las cronologías centroandinas, haciéndolas más apropiadas para contestar las preguntas que se formulan los arqueólogos. Pensando en ese potencial, aquí reviso la historia del uso del método radiocarbónico en la arqueología de los Andes Centrales. Después pongo el foco en los asuntos prácticos que se enfrentan los arqueólogos que trabajan en la región: calibración, reservorio marino, articulación de fechados 14C entre si y con sus contextos arqueológicos, y el meta-análisis de compilaciones de fechados radiocarbónicos. Estos asuntos son importantes tanto para los arqueólogos que utilizan fechados 14C como para los que aspiran a ser consumidores informados y críticos de los fechados 14C publicados y las cronologías basadas en ellas.