W. H. Wills

The Origins of Southwestern Ceramic Containers: Women's Time Allocation and Economic Intensification

In the Greater American Southwest, ceramic containers were not manufactured until A.D. 1, as much as fifteen hundred years after the appearance of the first cultigens and eight hundred years after the appearance of the first ceramic figurines. A model for pottery origins developed by James A. Brown is tested using Southwestern data. Pottery containers were produced in conjunction with increasing sedentism and a greater dependence on cultivated foods. Production of ceramic containers increased womens workloads and created scheduling conflicts with subsistence pursuits. Southwestern women began producing pottery when changing social and economic conditions made the increased costs of ceramic manufacture acceptable. Changes in processing and storage technology involving the use of ceramic vessels increased the yields from cultivated crops.

Strontium Isotopes and the Reconstruction of the Chaco Regional System: Evaluating Uncertainty with Bayesian Mixing Models

Strontium isotope sourcing has become a common and useful method for assigning sources to archaeological artifacts. In Chaco Canyon, an Ancestral Pueblo regional center in New Mexico, previous studies using these methods have suggested that significant portion of maize and wood originate in the Chuska Mountains region, 75 km to the East. In the present manuscript, these results were tested using both frequentist methods (to determine if geochemical sources can truly be differentiated) and Bayesian methods (to address uncertainty in geochemical source attribution). It was found that Chaco Canyon and the Chuska Mountain region are not easily distinguishable based on radiogenic strontium isotope values. The strontium profiles of many geochemical sources in the region overlap, making it difficult to definitively identify any one particular geochemical source for the canyons pre-historic maize. Bayesian mixing models support the argument that some spruce and fir wood originated in the San Mateo Mountains, but that this cannot explain all 87Sr/86Sr values in Chaco timber. Overall radiogenic strontium isotope data do not clearly identify a single major geochemical source for maize, ponderosa, and most spruce/fir timber. As such, the degree to which Chaco Canyon relied upon outside support for both food and construction material is still ambiguous.

Shabik’Eschee Village in Chaco Canyon: Beyond the Archetype

Abstract This study revisits an earlier publication in this journal (Wills and Windes 1989) in which a settlement model involving seasonal mobility and limited household autonomy was outlined for Shabik’eschee Village, a Basketmaker III period (ca. A.D. 400–750) site in Chaco Canyon, New Mexico. We return to that work for three reasons. First, the original interpretation has been challenged and an alternative view offered in the form of a large sedentary village. Second, the issue of Basketmaker III sedentism is central to recent efforts to identify and understand a Neolithic Demographic Transition in the northern Southwest. And third, we have obtained new field data from Shabik’eschee and Chaco that contributes to this debate. We conclude that our understanding of Shabik’ eschee’s history is improved by both new data and the ongoing consideration of alternative models, but the site does not contain evidence for a sedentary village.

Prehistoric deforestation at Chaco Canyon

Ancient societies are often used to illustrate the potential problems stemming from unsustainable land-use practices because the past seems rife with examples of sociopolitical “collapse” associated with the exhaustion of finite resources. Just as frequently, and typically in response to such presentations, archaeologists and other specialists caution against seeking simple cause-and effect-relationships in the complex data that comprise the archaeological record. In this study we examine the famous case of Chaco Canyon, New Mexico, during the Bonito Phase (ca. AD 860–1140), which has become a prominent popular illustration of ecological and social catastrophe attributed to deforestation. We conclude that there is no substantive evidence for deforestation at Chaco and no obvious indications that the depopulation of the canyon in the 13th century was caused by any specific cultural practices or natural events. Clearly there was a reason why these farming people eventually moved elsewhere, but the archaeological record has not yet produced compelling empirical evidence for what that reason might have been. Until such evidence appears, the legacy of Ancestral Pueblo society in Chaco should not be used as a cautionary story about socioeconomic failures in the modern world.

The complex history of Pueblo Bonito and its interpretation

Pueblo Bonito in Chaco Canyon is one of the most iconic pre-Hispanic archaeological sites in the U.S. Southwest. Archaeologists refer to it as a great house in recognition of its massive scale, and often describe it as the centre of the Chaco world. Yet questions remain about Pueblo Bonito’s origins, sequence of construction, duration of occupation and abandonment. Here, the authors present new research that helps to clarify the early phases of occupation, and illuminates some of the problems inherent in reconstructing a building that was a perennial work in progress.

STABLE OXYGEN ISOTOPE SOURCING OF ARCHAEOLOGICAL FAUNA FROM CHACO CANYON, NEW MEXICO

Modern datasets provide the context necessary for accurate interpretations of isotopic data from archaeological faunal assemblages. In this study, we use the oxygen isotope ratios (δ18O) of modern small mammals from Chaco Canyon, New Mexico, to quantify expected isotopic variation in a local population. The δ18O values of local, modern small mammals encompass a broad range (−6.0‰ to 4.8‰ VPDB), which is expected given the extreme seasonal variation in the δ18O of precipitation on the Colorado Plateau (−11‰ to −3‰ VPDB). Isotopic ratios of small mammals obtained from excavated archaeological sites in Chaco Canyon (ca. AD 800 to 1200) show no significant differences with their modern counterparts, suggesting that there is no difference in the origins of the archaeological small-mammal collection and the modern, local Chaco Canyon small-mammal collection. In contrast, δ18O values of large mammals from Chaco archaeological sites are significantly different from those of modern specimens, reflecting a nonlocal, but also nonspecific, source in the past. Los datos isotópicos de los animales modernos pueden proporcionar información importante para la interpretación de los datos isotópicos procedentes de conjuntos faunísticos arqueológicos. En este estudio utilizamos las proporciones de isótopos de oxígeno (δ18O) de pequeños mamíferos modernos en Chaco Canyon, Nuevo México, para cuantificar la variación esperada para una única población local. El rango de valores de δ18O de los pequeños mamíferos locales en Chaco Canyon es amplio (-6,0‰ a 4,8‰ VPDB). Esto no es sorprendente, dada la considerable variación estacional de δ18O ligada a la precipitación en la meseta del Río Colorado (-11‰ a -3‰ VPDB). Las proporciones isotópicas de los pequeños mamíferos arqueológicos procedentes de los sitios excavados en Chaco Canyon (ca. 800–1200 dC) no difieren de manera significativa de las de los animales modernos. Esto sugiere que no hay diferencias de procedencia entre la colección arqueológica de pequeños mamíferos y los mamíferos locales modernos de Chaco Canyon. En cambio, los valores de δ18O de los mamíferos grandes de los sitios arqueológicos de la zona son muy distintos de los valores de mamíferos grandes modernos. Esto sugiere que los especímenes de mamíferos grandes arqueológicos tienen origen diferente y no local, aunque no especulamos sobre dónde pudo haber sido ese lugar.

The 5.1 ka aridization event, expansion of piñon-juniper woodlands, and the introduction of maize (Zea mays) in the American Southwest

Pollen analysis is frequently used to build climate and environmental histories. A distinct Holocene pollen series exists for Chaco Canyon, New Mexico. This study reports linear modeling and hypothesis testing of long distance dispersal pollen from radiocarbon-dated packrat middens which reveal strong relationships between piñon pine (Pinus edulis) and ponderosa pine (Pinus ponderosa). Ponderosa pollen dominates midden pollen assemblages during the early Holocene, while a rapid shift to a much higher proportion of piñon to ponderosa pine pollen between c. 5440 and 5102 cal. yr BP points to an aridization episode. This shift is associated with higher δ18O values in Southwest speleothem records relative to the preceding millennium. The period of aridization is followed by a sharp increase in El Niño/Southern Oscillation events that would have caused highly variable precipitation and lasted until c. 4200 cal. yr BP. Bayesian change-point analysis suggests that this aridization episode led to stable ecotonal boundaries for at least 3000 years. The piñon/ponderosa transition may have been caused by punctuated multiyear droughts, analogous to those in the 20th century. The earliest documented instance of Zea mays cultivation on the Colorado Plateau is around c. 3940 14C yr BP (c. 4364 cal. yr BP) (Hall SA (2010) Early maize pollen from Chaco Canyon, New Mexico, USA. Palynology 34(1): 125–137) in Chaco Canyon. The introduction of this labor-intensive cultigen from Mesoamerica may have been facilitated by changes in the regional ecosystems, specifically by an increase in piñon trees, that promoted increasing human territoriality. Linear modeling and hypothesis testing can complement traditional palynological techniques by adding greater resolution in vegetation patterning to climate/environmental histories.