Chaco Canyon was Reliant on Food Imports

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."

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PreColumbian American Southwest Went Through Cycles of Boom/Bust

The heavily studied yet largely unexplained disappearance of ancestral Pueblo people from southwest Colorado is "the most vexing and persistent question in Southwestern archaeology," according to the New York Times.

But it's not all that unique, say Washington State University scientists. Writing in the journal Science Advances, they say the region saw three other cultural transitions over the preceding five centuries. The researchers also document recurring narratives in which the Pueblo people agreed on canons of ritual, behavior and belief that quickly dissolved as climate change hurt crops and precipitated social turmoil and violence.

"The process of releasing one's self from those canons, the process of breaking that down, can occur very quickly and occurred very quickly four times in the Pueblo past," said Kyle Bocinsky, a WSU adjunct faculty member in anthropology and director of sponsored projects for the Crow Canyon Archaeological Center in Cortez, Colo. The article grew out of work toward Bocinsky's WSU doctorate.

Funded by the National Science Foundation, Bocinsky, WSU Regents Professor Tim Kohler and colleagues analyzed data from just over 1,000 southwest archaeological sites and nearly 30,000 tree-ring dates that served as indicators of rainfall, heat and time. Their data-intensive approach, facilitated by climate reconstructions run at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, gives a remarkably detailed picture of year-to-year changes.

This is particularly important as droughts of just five or ten years were enough to prompt major shifts in the small niches where Pueblo people grew maize, their major crop.

The niches, said Kohler, were "woven together with a web of ceremony and ritual that required belief in the supernatural" to ensure plentiful rain and good crops. When rains failed to appear, he said, the rituals were delegitimized.

"Then there's a point where people say, 'This isn't working. We're leaving,'" he said.

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Long-distance Wood Procurement and the Chaco Florescence

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.

Chaco Canyon Anasazi/Ancestral Puebloans Shifted Sources of Wood Concurrently With Changes in Culture, Masonry

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.

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What Happened to the Anasazi/Ancestral Puebloans of Mesa Verde?

Vultures carve lazy circles in the sky as a stream of tourists marches down a walkway into Colorado's Spruce Canyon. Watching their steps, the visitors file along a series of switchbacks leading to one of the more improbable villages in North America—a warren of living quarters, storage rooms, defensive towers and ceremonial spaces all tucked into a large cleft in the face of a cliff.

When ancient farmers built these structures around the year 1200, they had nothing like the modern machinery that constructed the tourist walkway. Instead, the residents had to haul thousands of tonnes of sandstone blocks, cut timber and other materials down precarious paths to build the settlement, known as Spruce Tree House, in Mesa Verde National Park.

“Why would people live here? That's an important question. It's not an easy place to reach,” says Donna Glowacki, an archaeologist now at the University of Notre Dame in Indiana, as she walks among the ruins. Even more perplexing is what happened after they settled there. The villagers occupied their cliffside houses for just a short time before everyone suddenly picked up and left. So did all the other farmers living in the Four Corners region of the American Southwest, where the modern states of Colorado, New Mexico, Utah and Arizona meet.

All together, nearly 30,000 people disappeared from this area between the mid-1200s and 1285, making it one of the greatest vanishing acts documented in human history. What had been one of the most populous parts of North America became almost instantly a ghost land.

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Hat tip to Randy.

How Southwestern America's Pueblo's Fell Apart, Physically

The pueblo decomposition model: A method for quantifying architectural rubble to estimate population size

Authors:

Duwe et al

Abstract:

While most archaeological measures of population rely on material proxies uncovered through excavation (rooms, hearths, etc.), we identify a technique to estimate population at unexcavated sites (the majority of the archaeological record). Our case study focuses on ancestral Tewa Pueblo villages in northern New Mexico. Uninhabited aerial vehicle (UAV) and instrument mapping enables us to quantify the volume of adobe architectural rubble and to construct a decomposition model that estimates numbers of rooms and roofed over space. The resulting metric is applied at ten Pueblo villages in the region to ‘rebuild’ architecture, and calculate maximum architectural capacity and the maximum extent of population size. While our focus is on population histories for large Classic period (A.D. 1350–1598) pueblos in the American Southwest, the model and method may be applied to a variety of archaeological contexts worldwide and is not limited to building material, site size, or construction technique.

Parrots Push Chaco Canyon (Anasazi/Puebloan) Culture/MesoAmerican Trade Origin Between 800 to 900 AD

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.

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paper link.

The Anasazi of the Chaco Culture Violently Clashed With Mesa Verde

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.

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Bucking Mainstream Thought: Chaco Canyon NOT Abandoned for Environmental Reasons

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.

Demographics of the Baby Boom of Anasazi America

Long and spatially variable Neolithic Demographic Transition in the North American Southwest

Authors:

Kohler et al

Abstract:

In many places of the world, a Neolithic Demographic Transition (NDT) is visible as a several-hundred-year period of increased birth rates coupled with stable mortality rates, resulting in dramatic population growth that is eventually curtailed by increased mortality. Similar processes can be reconstructed in particular detail for the North American Southwest, revealing an anomalously long and spatially variable NDT. Irrigation-dependent societies experienced relatively low birth rates but were quick to achieve a high degree of sociopolitical complexity, whereas societies dependent on dry or rainfed farming experienced higher birth rates but less initial sociopolitical complexity. Low birth rates after A.D. 1200 mark the beginning of the decline of the Hohokam. Overall in the Southwest, birth rates increased slowly from 1100 B.C. to A.D. 500, and remained at high levels with some fluctuation until decreasing rapidly beginning A.D. 1300. Life expectancy at 15 increased slowly from 900 B.C. to A.D. 700, and then increased rapidly for 200 y before fluctuating and then declining after A.D. 1400. Life expectancy at birth, on the other hand, generally declined from 1100 B.C. to A.D. 1100/1200, before rebounding. Farmers took two millennia (∼1100 B.C. to ∼A.D. 1000) to reach the carrying capacity of the agricultural niche in the Southwest.

Using Drones to Thermally map a Chaco-era Anasazi/Ancestral Puebloan Site

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.

Ancestral Pueblo Indians (Anasazi) had Huge Trade Network

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."

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Anasazi Choco Canyon

Chemical residues found on pottery jar shards reveal that the practice of drinking chocolate had spread at least as far north as Chaco Canyon (map) in northern New Mexico by A.D. 1000 to 1125—400 years earlier than chocolate was thought to have reached what is now the United States.

The discovery suggests a vast trade network helped deliver chocolate from Central America, where the seeds of the cacao tree were first transformed into beverages some 3,000 years ago.

"That's a long way to go for something that you don't need for survival, [something] that's more of a delicacy," said Patricia Crown, an anthropologist at the University of New Mexico and co-author of the new study, which appears in tomorrow's issue of the journal Proceedings of the National Academies of Science.

Anyone writing alternate history along the lines of Doug's old Bronze Age New World TL really ought to take note. The trade was nontrivial: they also found parrots and metal bells previously. It's PDC too. ;)

(the title really is a pun, isn't it?)