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The construction of great houses during the Bonito Phase (ca. AD 850–1200) in Chaco Canyon, New Mexico, required massive amounts of building material and efficient mobilization and coordination of large labor pools. We employ least cost path analysis (LCA) to explore the potential communication network among great house communities in the Chaco “core” area and its relevance in managing sustained labor for constructing great houses. The results suggest that that the primary sources of labor for communal building projects were agricultural communities located within one to three hours of the largest buildings in the canyon.

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.

There are two large mounds comprised of enormous quantities of construction debris and discarded household debris associated with rapid growth of the Pueblo Bonito great house in Chaco Canyon between ca. CE 1040 and 1100. There is some debate among specialists as to whether these features were expedient refuse middens or constructed platform mounds or something in between, and thus whether they index political processes linked to control of labor by elites. Although originally investigated by archaeologists between 1896 and 1927, this study presents the first detailed formation history for each mound, based on recent fieldwork by the University of New Mexico. We argue that the mounds were not the product of institutionalized political power as assumed for platform mounds in other parts of North America but rather reflect local landscape changes associated with complex social negotiations during a period of rapid social transformation.

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.

Agricultural intensification is widely assumed by archaeologists to have been a catalytic factor in the development of social complexity in Chaco Canyon, New Mexico, between ca. AD 850 and 1200. In this perspective, water control technology resulted in surplus food production which was controlled by elites to finance the construction of massive buildings (“great houses”). However, recent fieldwork and archival research has been unable to substantiate this view of technological innovation promoting surplus agricultural production. An alternative explanation for economic growth is social transactions involving labor rather than food.

Recent archaeological investigations at Pueblo Bonito in Chaco Canyon reveal that residents constructed a large diversion channel during the eleventh century A.D. as dramatic growth resulted in the expansion of the building onto the main valley floor. Sediments in the diversion channel reflect repeated episodes of flooding, rather than slow moving water typically found in irrigation canals, and archaeobotanical data indicate deposition during late summer or early fall. Although an agricultural function is possible, the channel may have been built primarily to divert floodwaters away from Pueblo Bonito while providing a nearby water source for construction and domestic use. The diversion channel was destroyed by the entrenchment of the “Bonito paleo-channel” in the late A.D. 1000s, and then buried by a combination of cultural debris and valley flooding. Although the canyon stream system changed throughout the occupation of Pueblo Bonito, there is no evidence that the formation of a deep natural channel in the floodplain had any negative effect on the growth of the great house

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.

The great houses of Chaco Canyon (ca. A.D. 850–1150) are widely assumed to represent cosmological meaning through the orientation of walls and other features to celestial events. Archaeological models of such relationships are considered cosmographic. A prominent feature of these models is a lone pine tree at Pueblo Bonito that has been interpreted as a “tree of life” symbolically connecting the physical and heavenly worlds. This study suggests that this interpretation is inconsistent with contextual data and should be dismissed. Future cosmographic research in Chaco should endeavor to develop methods of independent verification that will strengthen inferences about cosmological symbolism in architecture.

The Bonito Phase (ca. AD 860–1140) in Chaco Canyon is widely recognized as one of the primary sources of information about emergent social complexity in prehispanic North America. Large masonry buildings called “great houses,” such as Pueblo Bonito, are iconic symbols of the rapid rise of a powerful society based on the ability to harness labor to prolonged construction projects. It is clear that the political forces at work during the Bonito Phase had an agricultural foundation, presumably in the financing of construction through food surpluses, but the actual nature of farming in Chaco is surprisingly opaque to archaeologists. Indeed, many researchers have concluded that farming in Chaco Canyon was too constrained by poor soils to have supported the dynamic developments associated with the massive stone structures and extensive trade systems of the Bonito Phase. The popular perspective that Chaco was mysterious or enigmatic is largely a response to this view of the canyon as agriculturally marginal. In this study we argue that a predictive model of potential agricultural productivity that includes other portions of the canyon besides the floodplain indicates that Chaco was not marginal for farming. The results of this analysis suggest that great house communities may have been sited to control local production zones and that some great houses may have been linked to others in order to manage multiple agricultural areas.

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.

The Bonito Phase (ca. AD 850 to 1140) in Chaco Canyon, New Mexico, is widely assumed by archeologists to reflect the growth and decline of a coherent sociopolitical entity, one of the classic examples of emergent social complexity among ancient indigenous North American populations ending in a societal collapse. This understanding of Chaco is based, in part, on the interpretation of temporal changes in material culture as intentional efforts to maintain cultural identity and continuity in the face of social disruption. In this study, I suggest that the Bonito Phase actually encompassed at least one major episode of cultural discontinuity, calling into question the perception of a distinct “Chaco society.” Instead, patterns of material production in Chaco point to multiple cultural identities linked to serial reoccupation of the canyon.

Patterns of use of ceramic objects and masonry architecture at Chaco Canyon in the southwestern United States indicate refurbishing of some vessels and architectural forms. Ceramic cylinder jars show evidence for obliteration of earlier designs and subsequent repainting and refiring of new designs. Communal structures, or kivas, were dismantled and rebuilt. Three possible explanations for these patterns are explored: revision of errors, restoration of worn surfaces, or ritual renewal. Renewal appears the most likely explanation for most of the patterning seen, providing a fuller picture of Chacoan ritual life and beliefs. Implications for research in the Chaco area and greater Southwest are discussed.

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.

Changes in prehistoric Southwestern architecture have been interpreted as the result of increasing dependence on agriculture through time which promoted greater sedentism. Recent archaeological research has produced data that point to changes in labor organization rather than agricultural productivity as the factors that most likely favored new forms of domestic architecture. In fact, some of the most striking temporal shifts in residential architecture may have been associated with declining agricultural productivity.

New excavations at the SU site have provided chronological and artifactual data leading to several revisions of long-standing interpretations of this important early pithouse settlement in the Mogollon Highlands of western New Mexico. As the type site for the Pine Lawn phase, conventionally dated at ca. A.C. 200 to 550, the SU site has been assumed to represent evidence for a cultural continuum between the preceramic and ceramic horizons in this region. This study presents information indicating that although a preceramic occupation is present at the SU site, stratigraphic and chronological data supporting a cultural continuum from the preceramic are ambiguous. In addition, chronological data from the SU site and other local early ceramic period sites do not indicate pottery use until about A.C. 450 or later, suggesting that the beginning of ceramic manufacture in the rugged highland portions of the Mogollon cultural area occurred later than in most other areas of the American Southwest. In additi...

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 women's 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 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 studiesusing these methods have suggested that significant portion of maize and wood originate in the Chuska Mountains region, 75 km to the West [corrected]. 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 canyon's 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.

Relative Time Period: Follows the Early Desert Archaic tradition, precedes the Late Desert Archaic tradition.

The appearance of pithouse settlements in the American Southwest that have multihabitation structures has been considered evidence for the emergence of "village" social organization. The interpretation that village systems are reflected in pithouse architecture rests in great part on the assumption that large sites correspond to large, temporally stable social groups. In this article we examine one of the best known pithouse settlements in the Southwest—Shabik’eschee Village in Chaco Canyon, New Mexico—and argue that the site may represent episodic aggregation of local groups rather than a sedentary occupation by a single coherent social unit.

Recent archaeological research in the American Southwest is rapidly altering long-held perspectives on early agricultural adaptations. The adoption of maize and squash is now reliably dated to ca. 1200 B.C., rather than 4000–2000 B.C. as previously thought, and new sites have been found in a variety of unexpected ecological settings. These emerging spatiotemporal patterns suggest that the development of sedentary communities after A.D. 500 may have been the result of changing systems of foraging, instead of simply a greater dependence on agricultural production.

IN 1949 THE SCIENTIFIC community was astonished by the discovery of the oldest known corn (Zea mays) in the dust-dry deposits of Bat Cave, a rockshelter in the rugged Mogollon Mountains of Catron County, New Mexico (Mangelsdorf 1950). Excavations at Bat Cave were jointly undertaken by Harvard University and the University of New Mexico, and the great impact of the finds was the result of a pioneering application of radiocarbon dating. The radiocarbon method allowed researchers to assess the age of organic material, and at Bat Cave it indicated an antiquity for Southwestern agriculture (ca. 6000 B.P.) that was several thousand years older than expected (Dick 1965). The Bat Cave results were followed several years later by excavations at Tularosa Cave, also in the Mogollon Mountains, that confirmed the region as the earliest known agricultural center in North America (Martin et al. 1952) and soon led to a productive search for early agriculture in other parts of the New World (Stark 1986).1 During the 1960s New Mexico continued to provide significant information on the evolution of prehistoric agricultural systems. The Albuquerque area was the scene of several excavations, particularly on the mesas west of the Rio Grande, that produced the earliest known examples of Maiz de Ocho, a variety that provided the genetic material necessary for the spread of corn agriculture to the northern areas of North America (Galinat, Reinhart, and Frisbie 1970; Galinat and Gunnerson 1963). The high yield and increased adaptability to varying environments found in Maiz de Ocho eventually contributed to the economic basis of complex social developments throughout eastern North America. By the late 1960s archaeology was undergoing major changes in research orientation, and in 1968 Lewis R. Binford of the University of New Mexico published a paper that marked a radical shift in the way archaeologists study agricultural origins. Binford (1968) proposed that cultivation was a result of intensified foraging activity caused by demographic imbalances between human populations and the carrying capacity of their environment. He advocated treating hunter-gatherer economies systemically, observing that their various procurement tactics were interrelated rather than functionally separate. Nearly all subsequent researchers have sought the causes of incipient food production within the framework of changing patterns of hunter-gatherer land use (see, e.g., Flannery 1973, 1986; Hayden 1981). In recent years field investigations of early agricultural sites have been an important research focus in New Mexico. New research at Bat Cave has led to a reinterpretation of its age, with the earliest maize now being dated almost

No correlation was found between calcium applied at an equivalent rate of either 897 or 1,793 kg/ha in an artificial medium and the amount of pod breakdown incited by either Pythium myriotylum or Rhizoctonia solani. R. solani appeared to be the dominant organism although the isolates tested exhibited a wide range of pathogenicity to peanut pods.