The ancient inhabitants of New Mexico's Chaco Canyon, the zenith of Pueblo culture in the Southwest a thousand years ago, likely had to import corn to feed the multitudes residing there, says a new University of Colorado Boulder study.
CU Boulder scientist Larry Benson said the new study shows that Chaco Canyon - believed by some archeologists to have been populated by several thousand people around A.D. 1100 and to have held political sway over an area twice the size of Ohio - had soils that were too salty for the effective growth of corn and beans.
"The important thing about this study is that it demonstrates you can't grow great quantities of corn in the Chaco valley floor," said Benson, an adjunct curator of anthropology at the University of Colorado Museum of Natural History. "And you couldn't grow sufficient corn in the side canyon tributaries of Chaco that would have been necessary to feed several thousand people.
"Either there were very few people living in Chaco Canyon, or corn was imported there."
Long-distance wood procurement and the Chaco florescence
Author:
Watson
Abstract:
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.
The wood in the monumental "great houses" built in Chaco Canyon by ancient Puebloans came from two different mountain ranges, according to new research from the University of Arizona Laboratory of Tree-Ring Research.
The UA scientists are the first to report that before 1020, most of the wood came from the Zuni Mountains about 50 miles (75 km) to the south. The species of tree used in the buildings did not grow nearby, so the trees must have been transported from distant mountain ranges.
About 240,000 trees were used to build massive structures, some five stories high and with hundreds of rooms, in New Mexico's arid, rocky Chaco Canyon during the time period 850 to 1140. The buildings include some of the largest pre-Columbian buildings in North America.
"The casual observer will see hundreds and hundreds and hundreds of beams sticking out of the walls. There's wood all over the place in these structures," said lead author Christopher Guiterman. "They're built out of stone and wood."
To figure out where the trees for the beams had grown, Guiterman used a method known as dendroprovenance that had not been used in the American Southwest before.
By 1060, the Chacoans had switched to harvesting trees from the Chuska Mountains about 50 miles (75 km) to the west.
The switch in wood sources coincides with several important developments in Chacoan culture, said Guiterman, a doctoral candidate in UA's School of Natural Resources and the Environment.
"There's a change in the masonry style--the architectural signature of the construction. There's a massive increase in the amount of construction--about half of 'downtown Chaco' houses were built at the time the wood started coming from the Chuska Mountains," he said.
By reviewing archaeological records, the team found other materials coming to Chaco from the Chuskas at the same time.
Somehow, colorful tropical scarlet macaws from tropical Mesoamerica -- the term anthropologists use to refer to Mexico and parts of northern Central America -- ended up hundreds of miles north in the desert ruins of an ancient civilization in what is now New Mexico.
Early scientists began excavating the large Pueblo settlements in Chaco Canyon in northwestern New Mexico and found the birds' remains in the late 1890s, but only recent radiocarbon dating of the physical evidence has pushed back the time period of sophisticated Pueblo culture by at least 150 years, according to a paper published today in the Proceedings of the National Academy of Sciences.
Co-author and archaeologist Stephen Plog, the University of Virginia's David A. Harrison Professor of Anthropology, worked with Adam S. Watson of the American Museum of Natural History, Douglas J. Kennett of Pennsylvania State University and a team of researchers from the museum and other universities to have macaw bones dated and interpret the results.
Using accelerator mass spectrometry radiocarbon methods with high precision in dating, the researchers found the macaw skeletal remains were much older than previously thought -- from as early as the late A.D. 800s -- signaling what researchers theorize was a Pueblo culture established enough to form relationships with Mesoamerican cultures to the south. Plog said archaeologists had typically put the beginning of the apex of ancestral Pueblo civilization in Chaco at A.D. 1040, based on other means such as tree-ring dating that suggested a major architectural expansion began at that time.
Anthropologists had already determined that the ancient Pueblo developed a complex social and religious hierarchy in the canyon, reflected in their distinctive architecture. They have posited that Chaco's 'golden century' or the Chaco 'florescence' occurred from A.D. 1040 to 1110, coinciding with a major expansion of the 'great houses.' These great houses contained clustered complexes of rooms for large gatherings, lodgings, storage, burial and religious rituals. Pueblo Bonito, with about 650 rooms in the largest of the great houses of Chaco Canyon, is where most of the macaws were recovered.
'In general, most researchers have argued that emergence of hierarchy, and of extensive trade networks that extended into Mexico coincided with what we see as other aspects of the Chaco florescence: Roads being built outward from Chaco and the formation of what are called Chaco outliers that mimic the architecture seen in the cultural center,' Plog said.
The radiocarbon dating project, led by Plog, Watson, and Kennett, showed that the bird remains came from as early as the late A.D. 800s to mid 900s. The earlier dating suggests that the rise of Pueblo sociopolitical complexity developed earlier than previously thought.
It's a given that, in numbers terms, the 20th Century was the most violent in history, with civil war, purges and two World Wars killing as many as 200 million people.
But on a per-capita basis, Washington State University archaeologist Tim Kohler has documented a particularly bloody period more than eight centuries ago on what is now American soil. Between 1140 and 1180, in the central Mesa Verde of southwest Colorado, four relatively peaceful centuries of pueblo living devolved into several decades of violence.
Writing in the journal American Antiquity, Kohler and his colleagues at WSU and at the University of Colorado-Boulder document how nearly nine out of ten sets of human remains from that period had trauma from blows to either their heads or parts of their arms.
"If we're identifying that much trauma, many were dying a violent death," said Kohler, whose study was funded by the National Science Foundation.
Yet at the same time, in the northern Rio Grande region of what is now New Mexico, people had far less violence while experiencing similar growth and, ostensibly, population pressures. Viewed together, said Kohler, the two areas offer a view into what motivates violence in some societies but not others. The study also offers more clues to the mysterious depopulation of the northern Southwest, from a population of about 40,000 people in the mid-1200s to none 30 years later.
From the days they first arrived in the Southwest in the 1800s, anthropologists and archaeologists have for the most part downplayed evidence of violent conflict among the early farmers in the region. A minority raised the specter of violence but lacked a good measure for it.
"Archaeologists with one or two exceptions have not tried to develop an objective metric of levels of violence through time," said Kohler. "They've looked at a mix of various things like burned structures, defensive site locations and so forth, but it's very difficult to distill an estimate of levels of violence from such things. We've concentrated on one thing, and that is trauma, especially to the head and portions of the arms. That's allowed us to look at levels of violence through time in a comparative way."
Meanwhile, Kohler and his colleagues are examining the role of factors like maize production, changes to the climate, and growing population in changing levels of violence. A paper of his published in June in the Proceedings of the National Academy of Sciences found that the Southwest had a baby boom between 500 and 1300 that likely exceeded any population spurt on earth today.
Both the central Mesa Verde and northern Rio Grande experienced population booms, said Kohler, but surprisingly, the central Mesa Verde got more violent while the northern Rio Grande grew less so.
Prehistoric deforestation at Chaco Canyon?
Authors:
Wills et al
Abstract:
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.
Archaeological aerial thermography: a case study at the Chaco-era Blue J community, New Mexico
Authors:
Casana et al
Abstract:
Despite a long history of studies that demonstrate the potential of aerial thermography to reveal surface and subsurface cultural features, technological and cost barriers have prevented the widespread application of thermal imaging in archaeology. This paper presents a method for collection of high-resolution thermal imagery using an unmanned aerial vehicle (UAV), as well as a means to efficiently process and orthorectify imagery using photogrammetric software. To test the method, aerial surveys were conducted at the Chaco-period Blue J community in northwestern New Mexico. Results enable the size and organization of most habitation sites to be readily mapped, and also reveal previously undocumented architectural features. Our easily replicable methodology produces data that rivals traditional archaeological geophysics in terms of feature visibility, but which can be collected very rapidly, over large areas, with minimal cost and processing requirements.
About a millennium ago, the ancestral Pueblo Indians in the Chaco Canyon in northwestern New Mexico obtained their precious turquoise using a large trade network spanning several states, new research reveals.
In the new study, researchers traced Chaco Canyon turquoise artifacts back to resource areas in Colorado, Nevada and southeastern California. The results definitively show, for the first time, that the ancestral Puebloans — best known for their multistoried adobe houses — in the San Juan Basin area of New Mexico did not get all of their turquoise from a nearby mining site, as was previously believed.
What's more, the study reveals the Puebloan people in the Moapa Valley of southern Nevada obtained some of their turquoise from as far away as Colorado and New Mexico, suggesting the trade network ran in both directions.
"People usually think of the Chaco Canyon as this big center [for turquoise]," said study lead author Sharon Hull, an anthropologist at the University of Manitoba in Winnipeg, Canada. "But we show that people were bringing the turquoise back and forth between the western and eastern sites."
