Adam S. Watson

Early procurement of scarlet macaws and the emergence of social complexity in Chaco Canyon, NM

Significance New accelerator mass spectrometer (AMS) 14C dates of scarlet macaw (Ara macao) skeletons from Chaco Canyon in northwestern New Mexico reveal the earliest (A.D. 900–975) direct evidence for procurement of this Neotropical species by Pueblo people from Mesoamerica. By directly dating the macaws, we demonstrate the existence of long-distance acquisition networks throughout much (A.D. 900–1150) of Chaco’s history. In contrast to models of societal evolution that attribute procurement of macaws to the 11th-century peak of Chacoan influence and architectural expansion, most 14C dates significantly predate this period. We propose that access to and control of these important status markers from Mesoamerica before A.D. 1040 was thus linked to the early formalization of social hierarchy in Chaco. High-precision accelerator mass spectrometer (AMS) 14C dates of scarlet macaw (Ara macao) skeletal remains provide the first direct evidence from Chaco Canyon in northwestern New Mexico that these Neotropical birds were procured from Mesoamerica by Pueblo people as early as ∼A.D. 900–975. Chaco was a prominent prehistoric Pueblo center with a dense concentration of multistoried great houses constructed from the 9th through early 12th centuries. At the best known great house of Pueblo Bonito, unusual burial crypts and significant quantities of exotic and symbolically important materials, including scarlet macaws, turquoise, marine shell, and cacao, suggest societal complexity unprecedented elsewhere in the Puebloan world. Scarlet macaws are known markers of social and political status among the Pueblos. New AMS 14C-dated scarlet macaw remains from Pueblo Bonito demonstrate that these birds were acquired persistently from Mesoamerica between A.D. 900 and 1150. Most of the macaws date before the hypothesized apogeal Chacoan period (A.D. 1040–1110) to which they are commonly attributed. The 10th century acquisition of these birds is consistent with the hypothesis that more formalized status hierarchies developed with significant connections to Mesoamerica before the post-A.D. 1040 architectural florescence in Chaco Canyon.

Archaeogenomic evidence reveals prehistoric matrilineal dynasty

For societies with writing systems, hereditary leadership is documented as one of the hallmarks of early political complexity and governance. In contrast, it is unknown whether hereditary succession played a role in the early formation of prehistoric complex societies that lacked writing. Here we use an archaeogenomic approach to identify an elite matriline that persisted between 800 and 1130 CE in Chaco Canyon, the centre of an expansive prehistoric complex society in the Southwestern United States. We show that nine individuals buried in an elite crypt at Pueblo Bonito, the largest structure in the canyon, have identical mitochondrial genomes. Analyses of nuclear genome data from six samples with the highest DNA preservation demonstrate mother–daughter and grandmother–grandson relationships, evidence for a multigenerational matrilineal descent group. Together, these results demonstrate the persistence of an elite matriline in Chaco for ∼330 years.

The Chaco Pilgrimage Model: Evaluating the Evidence From Pueblo Alto

Abstract Most recent attempts to understand the complex nature of the prehispanic occupation of Chaco Canyon in northwestern New Mexico often have postulated that the canyon was a center for pilgrimage fairs and ceremonies that attracted hundreds if not thousands of individuals from the surrounding region who may have resided in the canyon for significant periods of time. Scholars first proposed this model in the 1980s based on what they perceived as the unusual nature of Pueblo Alto, a Chacoan great house. In particular, they suggested that normal household activity and refuse disposal could not explain the deposition patterns in the Alto trash mound, the unusual number of ceramic vessels, and characteristics of the fauna recovered from the settlement. We evaluate this argument focusing primarily on the ceramic and faunal evidence and conclude that neither the ceramic nor the faunal data support the occurrence of periodic fairs, festivals, dances or pilgrimages of the scale that have been postulated.

Surface analysis of stone and bone tools

Microwear (use-wear) analysis is a powerful method for identifying tool use that archaeologists and anthropologists employ to determine the activities undertaken by both humans and their hominin ancestors. Knowledge of tool use allows for more accurate and detailed reconstructions of past behavior, particularly in relation to subsistence practices, economic activities, conflict and ritual. It can also be used to document changes in these activities over time, in different locations, and by different members of society, in terms of gender and status, for example. Both stone and bone tools have been analyzed using a variety of techniques that focus on the observation, documentation and interpretation of wear traces. Traditionally, microwear analysis relied on the qualitative assessment of wear features using microscopes and often included comparisons between replicated tools used experimentally and the recovered artifacts, as well as functional analogies dependent upon modern implements and those used by indigenous peoples from various places around the world. Determination of tool use has also relied on the recovery and analysis of both organic and inorganic residues of past worked materials that survived in and on artifact surfaces. To determine tool use and better understand the mechanics of wear formation, particularly on stone and bone, archaeologists and anthropologists have increasingly turned to surface metrology and tribology to assist them in their research. This paper provides a history of the development of traditional microwear analysis in archaeology and anthropology and also explores the introduction and adoption of more modern methods and technologies for documenting and identifying wear on stone and bone tools, specifically those developed for the engineering sciences to study surface structures on micro- and nanoscales. The current state of microwear analysis is discussed as are the future directions in the study of microwear on stone and bone tools.

A comparative assessment of texture analysis techniques applied to bone tool use-wear

The study of bone tools, a specific class of artifacts often essential to perishable craft production, provides insight into industries otherwise largely invisible archaeologically. Building on recent breakthroughs in the analysis of microwear, this research applies confocal laser scanning microscopy and texture analysis techniques drawn from the field of surface metrology to identify use-wear patterns on experimental and archaeological bone artifacts. Our approach utilizes both conventional parameters and multi-scale geometric characterizations of the areas of worn surfaces to identify statistical similarities as a function of scale. The introduction of this quantitative approach to the study of microtopography holds significant potential for advancement in use-wear studies by reducing inter-observer variability and identifying new parameters useful in the detection of differential wear-patterns.

Long-distance wood procurement and the Chaco florescence.

First documented during a military reconnaissance in 1849, Chaco Canyon and the Ancestral Pueblo society that flourished therein [850–1140 Common Era (CE)] have been the focus of archaeological investigation for more than a century. Beginning in the early ninth century CE, the inhabitants of farming communities lining a 14-km stretch of the lower canyon in present-day northwest New Mexico erected massive free-standing masonry pueblos, or “great houses.” Great houses are monumental in scale and are among the most iconic and remarkable feats associated with Chacoan societal development. The construction of one multistory great house, Pueblo Bonito, with at least 650 masonry rooms, required the Chacoan people to quarry 50,000 tons of sandstone and harvest and transport more than 50,000 pine (Pinus sp.), fir (Abies sp.), and spruce (Picea sp.) trees from distant (60−80 km) montane forests (Fig. 1). Guiterman et al.’s (1) analysis of a spatially broad sample of construction timbers from 7 of 11 great houses in Chaco Canyon documents the chronology and spatial extent of wood harvesting strategies and reveals a significant and previously unknown wood source.

Soil analysis in discussions of agricultural feasibility for ancient civilizations: A critical review and reanalysis of the data and debate from Chaco Canyon, New Mexico.

Questions about how archaeological populations obtained basic food supplies are often difficult to answer. The application of specialist techniques from non-archaeological fields typically expands our knowledge base, but can be detrimental to cultural interpretations if employed incorrectly, resulting in problematic datasets and erroneous conclusions not easily caught by the recipient archaeological community. One area where this problem has failed to find resolution is Chaco Canyon, New Mexico, the center of one of the New World’s most vibrant ancient civilizations. Discussions of agricultural feasibility and its impact on local population levels at Chaco Canyon have been heavily influenced by studies of soil salinity. A number of researchers have argued that salinized soils severely limited local agricultural production, instead suggesting food was imported from distant sources, specifically the Chuska Mountains. A careful reassessment of existing salinity data as measured by electrical conductivity reveals critical errors in data conversion and presentation that have misrepresented the character of the area’s soil and its potential impact on crops. We combine all available electrical conductivity data, including our own, and apply multiple established conversion methods in order to estimate soil salinity values and evaluate their relationship to agricultural productivity potential. Our results show that Chacoan soils display the same salinity ranges and spatial variability as soils in other documented, productive fields in semi-arid areas. Additionally, the proposed large-scale importation of food from the Chuska Mountains region has serious social implications that have not been thoroughly explored. We consider these factors and conclude that the high cost and extreme inflexibility of such a system, in combination with material evidence for local agriculture within Chaco Canyon, make this scenario highly unlikely. Both the soil salinity and archaeological data suggest that there is no justification for precluding the practice of local agriculture within Chaco Canyon.

Water uncertainty, ritual predictability and agricultural canals at Chaco Canyon, New Mexico

The Pueblo population of Chaco Canyon during the Bonito Phase (AD 800–1130) employed agricultural strategies and water-management systems to enhance food cultivation in this unpredictable environment. Scepticism concerning the timing and effectiveness of this system, however, remains common. Using optically stimulated luminescence dating of sediments and LiDAR imaging, the authors located Bonito Phase canal features at the far west end of the canyon. Additional ED-XRF and strontium isotope (87Sr/86Sr) analyses confirm the diversion of waters from multiple sources during Chaco’s occupation. The extent of this water-management system raises new questions about social organisation and the role of ritual in facilitating responses to environmental unpredictability.

Archaeogenomic evidence from the southwestern US points to a pre-Hispanic scarlet macaw breeding colony

Significance Archaeogenomic analysis of scarlet macaw bones demonstrates that the genetic diversity of these birds acquired by people in the southwestern United States (SW) between 900 and 1200 CE was exceedingly low. Only one mitochondrial DNA haplogroup (Haplo6) is present of the five historically known haplogroups in the lowland forests of Mexico and Central America. Phylogenetic analyses indicate the ancient macaw lineage in the SW shared genetic affinities with this wild lineage. These data support the hypothesis that a translocated breeding colony of scarlet macaws belonging to only one haplogroup existed some distance north of their endemic range, and SW peoples continuously acquired these birds from this unknown location for nearly 3 centuries, as no evidence currently exists for macaw breeding in SW. Hundreds of scarlet macaw (Ara macao cyanoptera) skeletons have been recovered from archaeological contexts in the southwestern United States and northwestern Mexico (SW/NW). The location of these skeletons, >1,000 km outside their Neotropical endemic range, has suggested a far-reaching pre-Hispanic acquisition network. Clear evidence for scarlet macaw breeding within this network is only known from the settlement of Paquimé in NW dating between 1250 and 1450 CE. Although some scholars have speculated on the probable existence of earlier breeding centers in the SW/NW region, there has been no supporting evidence. In this study, we performed an ancient DNA analysis of scarlet macaws recovered from archaeological sites in Chaco Canyon and the contemporaneous Mimbres area of New Mexico. All samples were directly radiocarbon dated between 900 and 1200 CE. We reconstructed complete or near-complete mitochondrial genome sequences of 14 scarlet macaws from five different sites. We observed remarkably low genetic diversity in this sample, consistent with breeding of a small founder population translocated outside their natural range. Phylogeographic comparisons of our ancient DNA mitogenomes with mitochondrial sequences from macaws collected during the last 200 years from their endemic Neotropical range identified genetic affinity between the ancient macaws and a single rare haplogroup (Haplo6) observed only among wild macaws in Mexico and northern Guatemala. Our results suggest that people at an undiscovered pre-Hispanic settlement dating between 900 and 1200 CE managed a macaw breeding colony outside their endemic range and distributed these symbolically important birds through the SW.