Chaco Canyon Research Articles

Evidence for human-caused founder effect in populations of Solanum jamesii at archaeological sites: II. Genetic sequencing establishes ancient transport across the Southwest USA.

The domestication of wild plant species can begin with gathering and transport of propagules by Indigenous peoples. The effect on genomic composition, especially in clonal, self-incompatible perennials would be instantaneous and drastic with respect to new, anthropogenic populations subsequently established. Reductions in genetic diversity and mating capability would be symptomatic and the presence of unique alleles and genetic sequences would reveal the origins and ancestry of populations associated with archaeological sites. The current distribution of the Four Corners potato, Solanum jamesii Torr. in the Southwestern USA, may thus reflect the early stages of a domestication process that began with tuber transport. Herein genetic sequencing (GBS) data are used to further examine the hypothesis of domestication in this culturally significant species by sampling 25 archaeological and non-archaeological populations. Archaeological populations from Utah, Colorado and northern Arizona have lower levels of polymorphic loci, unique alleles, and heterozygosity than non-archaeological populations from the Mogollon region of central Arizona and New Mexico. Principle components analysis, Fst values, and structure analysis revealed that genetic relationships among archaeological populations did not correspond to geographic proximity. Populations in Escalante, Utah were related to those on the Mogollon Rim (400 km south) and had multiple origins and significant disjunctions with those populations in Bears Ears, Chaco Canyon, and Mesa Verde sites. Movement of tubers from the Mogollon region may have occurred many times and in multiple directions during the past, resulting in the complex genetic patterns seen in populations from across the Four Corners region.

Ancient Wisdom in Northwest New Mexico

In an expanded version of an op-ed that highlighted a trip I took with a long-time friend, Larry Allums, I reflect on our experience of silence and centering during a visit to Pueblo Bonito, situated in Chaco Canyon in Northwest New Mexico in 2023. The experience for both of us brought us to reflect deeply on our cultural impulses toward distractions and outward actions that leave little or no room for inward pilgrimage to the center of who we are. Centering seems like a lost art of contemplation, of occasionally taking a measure of who we are and what our place in the world invites us to become. At Chaco Canyon, we entered the sacred space of its architecture. The rooms of Pueblo Bonito opened to the sky and to the kivas, underground mandala circles that may have been places of worship, of communal reflections, and rituals. We found in our pilgrimage a silence and deepening for which our daily lives make little space or time. We left the ancient pilgrimage site with a felt sense of the mystery of nature herself and of being embraced by the buildings and the desert as oases for renewal.

The Chaco Great North Road: Archaeological Survey and Ceramic Analysis by the San Juan Valley Archaeological Project

Research by Cynthia Irwin-Williams and the San Juan Valley Archaeological Project during the 1970s included investigations at Salmon Pueblo, near modern Bloomfield, NM. Interest focused on the construction and early occupation by immigrants from Chaco Canyon. Research also included the 80 km Great North Road, which joined Pueblo Alto at the southern end with Salmon Pueblo at the northern terminus. In order to investigate the North Road, Pierre Morenon conducted an intensive foot survey of the road trajectory and associated features. A large ceramic collection from the road and nearby sites was analyzed by Hayward Franklin. Pottery types dated mostly from 1050 to 1130 CE. A typical assemblage of decorated and utility pottery came northward from Chaco Canyon centers. Smaller amounts of northern San Juan pottery also occurred, signifying transport of ceramics and other goods southward from outliers at Salmon and Aztec Pueblos.

The Archaeology of the Bonito Paleochannel Cycle at Chaco Canyon, New Mexico: Implications for Communal and Household Level Investment in Water Management

This study examines the archaeological record for water management in Chaco Canyon, New Mexico, in relation to the Bonito Paleochannel cycle, ca. AD 1075–1150. We present evidence for a canal system at Pueblo Bonito that was destroyed by the entrenchment of the paleochannel. This canal system is associated with the peak of great house construction. Other water control features throughout the canyon were small and date to the period of paleochannel aggradation or afterward. We suggest that while the Pueblo Bonito canals represent some degree of corporate group investment, small features were managed at the household level. The limited archaeological evidence for formal water control infrastructure can be explained at least in part by the physical geography of Chaco Canyon, which we view as essentially a regional-scale water harvesting structure.

The Bonito Paleochannel in Chaco Canyon, New Mexico: Recent Research and Implications for Causality and Effects

During the late eleventh century AD, a episode of erosion in Chaco Canyon, New Mexico, threatened to destroy portions of the Pueblo Bonito great house and possibly other large buildings. Known as the Bonito Paleochannel, this large arroyo meant the loss of significant amounts of surface water from valley-wide flooding originating in upstream and tributary sources. We believe that erosion was probably the result of an increasing size and frequency of floods. There is no compelling evidence that agriculture was affected by the paleochannel but we hypothesize that great house construction became extremely difficult. Consequently, the impact of the Bonito Paleochannel cycle may have been felt most in the political economy.

A Diachronic Analysis of Obsidian Use at Chaco Canyon and the Influence of Social Factors on Obsidian Procurement

Chaco Canyon in New Mexico was the center of an extensive regional cultural system. The strength of Chaco's regional interactions has been partly defined by the presence of non–local goods including obsidian. We take a diachronic look at Chaco obsidian use from AD 500–1250 using the largest sample of XRF sourced obsidian available to date and combine this with technological analyses to identify significant changes in where and how Chacoans obtained and used obsidian. In the AD 700s obsidian from the more distant Jemez Mountains began to supplant the closer Mt. Taylor obsidian. The obsidian is of roughly equal quality, suggesting this shift relates to social factors and not raw material constraints. We find more variation over time in obsidian source use and acquisition strategies than previously noted. The patterning appears to relate to regional and local cultural diversity, social and organizational heterogeneity, and the development of new exchange networks.

The Greater Chaco Landscape: Ancestors, Scholarship, and Advocacy. Edited by Ruth M. Van Dyke and Carrie C. Heitman

Chaco Culture National Historical Park has long captured the attention of both the public and researchers. Despite strong disagreements over Chaco society, archaeologists had rarely spoken with descendent community members or included their voices directly in our broader understandings of this place and society. While this has been changing in recent years, we were missing a comprehensive volume that brought voices of descendent communities into conversation with Chaco researchers until the publication of The Greater Chaco Landscape: Ancestors, Scholarship, and Advocacy. As attested through the receipt of both the American Anthropological Association’s 2021 Engaged Anthropology Award and the Society for American Archaeology’s 2022 Popular Book Award, Van Dyke and Heitman compiled a compelling and wide-reaching volume bringing together an impressive breadth of scholarship and advocacy in The Greater Chaco Landscape. The book consists of seventeen chapters authored by individuals representing a range of perspectives, including academics, Indigenous community members, and National Park Service (NPS) and nonprofit employees. Stemming initially from an NPS initiative to better communicate the significance of the broader landscape and help protect the area from oil and gas development, Van Dyke and Heitman embraced a multimedia approach for the book with links to videos filmed either in Chaco Canyon or at Crow Canyon Archaeological Center during a seminar held in 2017 for all but the final chapter. Six of the chapters exist only as videos available on the University Press of Colorado’s website (http://read.upcolorado.com/projects/the-greater-chaco-landscape/) with helpful abstracts and links available within the hard copy of the book; this style of presenting information embraced the communication styles and strengths of the variety of contributors. Within the volume, chapters are divided into seven sections that highlight Understudied Landscape Dimensions; Indigenous Perspectives; Experiencing the Landscape; Geospatial Investigations and Big Data; and Management, in addition to introductory and concluding sections. The range of chapters strikes an important cord of multivocality, allowing many groups with stakes in Chaco Canyon and the surrounding region to contribute and be heard.

Were timbers transported to Chaco using tumplines? A feasibility study

Between 850 and 1200 CE, approximately 200,000+ large timbers were transported >75 km to Chaco Canyon using only human power. Researchers have proposed various load-carriage methods, speculated about how many porters would be needed and their speed of transport, but none have conducted empirical investigations. Here, we explore the feasibility of long-distance timber transport using tumplines, a technology well-evidenced in Chaco’s archaeological record. Two authors trained themselves to use tumplines and together carried a 60 kg timber 25 km with the timber oriented transverse to the walking direction. Total elapsed time was <10 h and walking speed averaged 4.5 km/hr. Individual walking speed with a 30 kg tumpline load was only ∼10 % slower than the preferred unladen walking speed. Timber transport to Chaco using tumplines is clearly feasible. We close by considering the implications of tumpline timber transport on the socio-political dynamics of Chacoan society.

Behind the Bears Ears: Exploring the Cultural and Natural Histories of a Sacred Landscape

Behind the Bears Ears: Exploring the Cultural and Natural Histories of a Sacred Landscape

Agricultural suitability of the Chaco Canyon Region, New Mexico: Implications for settlement patterning during the great house period (ca. AD 850 to 1200)

An agricultural suitability study for a 3,923 km2 area encompassing Chaco Canyon and the surrounding San Juan Basin in northwest New Mexico is presented with implications for farming during the great house period, ca. AD 850 to 1150 (Bonito Phase). The GIS-based analysis expands previous studies of a smaller geographical area and includes additional variables related to hydrology, soils and vegetation, as well as new or updated data sources for those variables. The results indicate that the largest great houses and surrounding communities were located in extensive areas of highly suitable agricultural lands and also point to previously unrecognized potential agricultural lands in nearby tributary drainages.

The Bonito Factor: How Unique Was Pueblo Bonito?

Pueblo Bonito is the largest and most centrally located great house in Chaco Canyon. One of its most striking attributes is its abundance of “exceptional deposits” of rare and unusual objects. It is unclear, however, whether Pueblo Bonito's assemblage reflects its unique status in the Chaco world or whether it is a product of sampling bias. To answer this question, we use binomial probabilities to interpret the significance of both finding, and of failing to find, exceptional deposits in other great houses. Our analysis suggests that excavated great houses can be grouped into three categories with respect to exceptional deposits: those that likely contain frequencies comparable to Pueblo Bonito; those with frequencies substantially less than Pueblo Bonito; and those that have been insufficiently sampled to make strong inferences. Variation and uncertainty in the presence of exceptional deposits have important implications for interpreting great house functions and Chacoan sociopolitical organization.

Transporting Timbers to Chaco Canyon: How Heavy, How Many Carriers and How Far/Fast?

A total of 200,000+ large timbers were transported >75 km to Chaco Canyon, a political and religious center in the precontact U.S. Southwest, using only human power. Previous researchers reported that typical primary roof beams (vigas) of Chacoan Great Houses averaged 0.22 m in diameter and 5 m in length with a mass of 275 kg. However, the 275 kg mass appears to be a miscalculation. Here, we calculate that a ponderosa pine timber of the stated dimensions would have a mass between 85–140 kg depending on the water content. While still a prodigious load, this recalculated mass requires revisions to estimates of the labor, time, and energy required to build Great Houses at Chaco. Based on contemporary measurements on professional load carriers and soldiers, we estimate that as few as two people could have carried an 85 kg timber across 100 km in as few as 21 h of active walking. 200,000+ maderas grandes fueron transportadas >75 km hasta el Cañón del Chaco, un centro político y religioso precolombino en el suroeste de los EE.UU., utilizando únicamente fuerza humana. Investigadores anteriores informaron que las vigas principales del techo de las Casas Grandes Chacoanas tenían un diámetro promedio de 0.22 m y una longitud de 5 m con una masa de 275 kg. La masa de 275 kg parece ser un error de cálculo. Aquí, calculamos que una madera de pino ponderosa de las dimensiones indicadas tendría una masa entre 85 y 140 kg dependiendo del contenido de agua. Aunque sigue siendo una carga prodigiosa, esta masa recalculada requiere revisiones de las estimaciones de la fuerza laboral, el tiempo y la energía totales necesarios para construir las Casas Grandes en Chaco. Basado en medidas contemporáneas sobre profesionales de carga y soldados, nosotros estimamos que tan solo 2 personas podrían cargar una madera de 85 kg a través de 100 km en tan solo ∼ 21 horas de caminata activa.

Communication in the Chaco World: A Consideration of Time and Labor Mobilization

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.

The Collapse of a Collective Society: Teuchitlán in the Tequila Region of Jalisco, Mexico

Cross-cultural research on ancient societies demonstrates that collective social formations tend to experience a more sudden collapse with relatively catastrophic effects compared to formations low in collectivity. The demise of collective formations often involves more pronounced social unrest and a more complete disintegration of the agrarian and sociopolitical systems. This article further probes this general finding using the case of Teuchitlán, in the Tequila region of Jalisco, Mexico, which lasted for ~700 years, from 350 B.C.E. to about 450/500 C.E., when it suddenly disappeared. It was characterized by power-sharing among multiple groups whose leaders employed varied political strategies. Structurally, Teuchitlán aligns with some of the precepts of collective action and good government, as it was inwardly focused and placed great emphasis on the joint production of the polity's resources, especially agriculture, as well as the equitable distribution of benefits, such as community feasting and ritual, and some form of political participation or voice (e.g., power-sharing). Scholars working in the area have invoked various environmental factors, demographic movements, natural disasters, the collapse of central places, and a breakdown in trade connections, among others, as causes of Teuchitlán's disintegration—and the answer may indeed lie in a combination of these phenomena. This article explores the major shifts in the institutions that comprised Teuchitlán, thereby presenting an alternative view of its nature and disappearance. Settlement patterns, architectural differences, ceramic decoration and vessel forms, and lithic technology from the period following Teuchitlán's collapse suggest major changes in ideology, economy, and politics. The placement of large centers along trade routes, coupled with increased control of interregional exchange, indicates a shift toward direct, discretionary control of polity revenues by political leaders with little benefit for the populace. As part of these changes, the human landscape became more ruralized. Teuchitlán is comparable to other well-known cases in the world where more collective forms of political organization met a similar fate, such as Chaco Canyon (Southwest USA), Jenne-jeno (Mali), and the Indus Civilization.

Ecosystem impacts by the Ancestral Puebloans of Chaco Canyon, New Mexico, USA.

The Ancestral Puebloans occupied Chaco Canyon, in what is now the southwestern USA, for more than a millennium and harvested useful timber and fuel from the trees of distant forests as well as local woodlands, especially juniper and pinyon pine. These pinyon juniper woodland products were an essential part of the resource base from Late Archaic times (3000–100 BC) to the Bonito phase (AD 800–1140) during the great florescence of Chacoan culture. During this vast expanse of time, the availability of portions of the woodland declined. We posit, based on pollen and macrobotanical remains, that the Chaco Canyon woodlands were substantially impacted during Late Archaic to Basketmaker II times (100 BC–AD 500) when agriculture became a major means of food production and the manufacture of pottery was introduced into the canyon. By the time of the Bonito phase, the local woodlands, especially the juniper component, had been decimated by centuries of continuous extraction of a slow-growing resource. The destabilizing impact resulting from recurrent woodland harvesting likely contributed to the environmental unpredictability and difficulty in procuring essential resources suffered by the Ancestral Puebloans prior to their ultimate departure from Chaco Canyon.

Patricia L. Crown (ed.). 2020. The House of the Cylinder Jars: Room 28 in Pueblo Bonito, Chaco Canyon. Albuquerque: University of New Mexico Press; 978-0-8263-6177-6 hardback $95.

Patricia L. Crown (ed.). 2020. The House of the Cylinder Jars: Room 28 in Pueblo Bonito, Chaco Canyon. Albuquerque: University of New Mexico Press; 978-0-8263-6177-6 hardback $95. - Volume 95 Issue 384

Ancient Grains: New Evidence for Ancestral Puebloan Use of Domesticated Amaranth

We report here the first domesticated amaranth (Amaranthus spp.) seeds to be identified at a Chacoan great house, from the northern New Mexico site known as Aztec North, where they were found in a context that dates to the mid to late twelfth century AD. Amaranth has long been recognized as an important prehispanic resource in this region, evidenced by the archaeological record of both wild and domesticated forms and by the traditional knowledge and practices of Indigenous communities. Wild amaranth and similar-appearing chenopod/goosefoot (Chenopodium spp.) seeds are routinely found in Ancestral Puebloan contexts. Recent archaeological testing at the Aztec North great house, a Chaco Canyon outlier associated with a post-Chacoan political center, has revealed the presence of uncharred domesticated amaranth seeds in a thin layer of ashy trash in a room at the rear of the great house. These seeds expand our understanding of domesticated amaranth in the American Southwest and suggest centuries of continuity of traditional amaranth cultivation within Puebloan communities.

Could the Ancestral Puebloans of Chaco Canyon, New Mexico, Have Depended on a Groundwater Ecosystem?

A thousand years ago, a population of Ancestral Puebloans occupied a high desert canyon in northwestern New Mexico, USA, where precipitation was limited and surface water scarce. Geological conditions, however, seem favorable for the production of a large Hypocrene springs system near the south canyon walls sufficient to have produced a groundwater ecosystem favorable for agriculture, tree growth, and human occupancy. A human-induced ecological impact is suggested as contributing to the dewatering of the springs, eventually reducing local agricultural production and, presumably, the suitability of Chaco Canyon for human occupancy.

Evidence for human-caused founder effect in populations of Solanum jamesii found at archaeological sites: I. Breeding experiments and the geography of sexual reproduction.

PremisePlant domestication can be detected when transport, use, and manipulation of propagules impact reproductive functionality, especially in species with self‐incompatible breeding systems.MethodsEvidence for human‐caused founder effect in the Four Corners potato (Solanum jamesii Torr.) was examined by conducting 526 controlled matings between archaeological and non‐archaeological populations from field‐collected tubers grown in a greenhouse. Specimens from 24 major herbaria and collection records from >160 populations were examined to determine which produced fruits.ResultsArchaeological populations did not produce any fruits when self‐crossed or outcrossed between individuals from the same source. A weak ability to self‐ or outcross within populations was observed in non‐archaeological populations. Outcrossing between archaeological and non‐archaeological populations, however, produced fully formed, seed‐containing fruits, especially with a non‐archaeological pollen source. Fruit formation was observed in 51 of 162 occurrences, with minimal evidence of constraint by monsoonal drought, lack of pollinators, or spatial separation of suitable partners. Some archaeological populations (especially those along ancient trade routes) had records of fruit production (Chaco Canyon), while others (those in northern Arizona, western Colorado, and southern Utah) did not.ConclusionsThe present study suggests that archaeological populations could have different origins at different times—some descending directly from large gene pools to the south and others derived from gardens already established around occupations. The latter experienced a chain of founder events, which presumably would further reduce genetic diversity and mating capability. Consequently, some archaeological populations lack the genetic ability to sexually reproduce, likely as the result of human‐caused founder effect.

The Pueblo Bonito mounds: Formation history, architectural context and representational fields

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.