More than a ceremonial, the ancient Chaco Canyon



While some current scientific theories point to the ancient Chaco Canyon, a distinctive archaeological site in the American Southwest, as a mere prehistoric ceremonial site populated only in sacred rituals, researchers at the University of Cincinnati are shaking this popular belief.

“The ancestral puebloans interacted with the local ecosystem in a way that has helped them adapt and thrive for over a millennium,” says David Lentz, professor of biology at UC and co-author of the study published in the journal. PLOS ONE titled “Impacts on the Ancestral Puebloan Ecosystem of Chaco Canyon, New Mexico, United States”.

“Many active researchers, however, align themselves with the idea that Chaco Canyon was too arid to support everyday life, arguing that the terrain and architectural structures were not permanent homes.

“Basically, they argue that Chaco Canyon’s massive stone and timber infrastructure, built over several centuries, was only used as a periodic ceremonial center and storage facility. But it was not that simple, and our evidence contradicts many currently proposed theories about the occupation of Chaco Canyon in ancient times.

Using on-site pollen and botany analysis and lidar mapping technology over the past decade, Lentz and a team of interdisciplinary researchers from the anthropology, geology, geography and biology departments of the ‘UC, including a select group of national collaborative scientists, reveal the impact of ancestral puebloans in Chaco Canyon during the great preeminence of culture.

“Our goals have focused on providing new insight into the sustainability of land use practices in the Chaco Canyon during the ancestral occupation of the pueblos,” Lentz adds. “Our results add new data that reveals measurable changes in juniper pine forests that occurred before 600 BC as the food supply system shifted from hunting and gathering to agricultural production.”

The change in the management of the ancestral food resources of the pueblos improved their ability to support larger populations in an arid and arid landscape for several centuries during the pre-Columbian era.

“But with their landscape changes, serious environmental ramifications have occurred. At the cost of a significant reduction in the density of trees in local forests, their activities ultimately contributed to a destabilizing environmental impact before their final exodus, ”adds Lentz.

This innovative interdisciplinary research is a stellar example of academic excellence, a standing tenet of UC’s strategic direction called Next Lives Here.

The first pueblo builders in the southwest

Chaco Canyon, a 34,000-acre center of social complexity located in the southwestern region of the United States, flourished during the height of Chaco culture between (AD 800 and AD 1140), a period that Lentz calls the phase Bonito.

During cultural flourishing, the hierarchical society was known for its elaborate ceremonial activities, the maintenance of long-distance trade routes and impressive architectural complexes, including more than a dozen immense structures that Lentz and archaeologists call “big houses”. One of the houses, known today as “Pueblo Bonito”, may have had over 600 rooms, including crypts that housed over 100 burials.

Previous research has revealed a system of roads that connect many Chaco cultivation sites with evidence of astronomical alignments, indicating that some of the structures were oriented towards the solstice sun and lunar stops.

In this context, archaeologists generally agree that Chaco Canyon functioned as a remote commercial center and a ceremonial site for the culture of the Chaco. So far, however, Lentz says the studies lacked evidence to support human management of the canyon’s precarious environment for day-to-day living.

Hidden clues

Using lidar aerial mapping technology and analysis of various ancient substances, including carbon isotopes, pollen content, macrobotanical remains, and soil chemistry, the research team assessed alternative hypotheses relating to the environmental impacts of ancestral puebloans.

It became clear to researchers that as the ancient pueblos struggled with the unpredictable environment, they kept their society prosperous for over 1,000 years through agriculture by cultivating a variety of crops such as corn, beans and squash in the canyon while simultaneously exploiting pinyon and juniper woods for architectural needs, food resources and firewood for cooking.

“It’s a very arid region,” says Lentz. “In arid forests, trees are essential for keeping the soil in place. When the people of Pueblo removed these woodlands, the result ultimately was severe erosion and deterioration of the cultivated land.

Researchers found gradual degradation of local forests beginning around 600 BC, much earlier than previously thought, Lentz says. Despite the clearing of forests, the inhabitants of the canyon have thrived for nearly a millennium through indigenous farming practices while using water-irrigation methods from neighboring tributaries of the Chaco, Escavada and Fajada Wash. .

Research team director Vernon Scarborough, professor of anthropology at UC, emphasizes the highly interdisciplinary nature of the project, noting that “While the aim of our work has been to identify ancient ancestral Puebloan water systems in this arid environment, past changes to the landscape have been more widely brought to light.

Of particular importance was the critical evidence of using local junipers as fuelwood for cooking locally grown corn, beans and squash, Lentz explains. Pine nuts were a valuable source of food, so the Chacoans protected the pines from overexploitation for firewood. But the junipers, an excellent source of fuel, were not spared by this extensive harvest.

“We found that a reduction in pine and juniper forests, with a loss of mainly junipers, occurred around the same time that there was an introduction of agriculture into the canyon with the technology of pottery making, ”Lentz explains. “Thanks to radiocarbon from previous studies, we know that forests were established and flourished in this region 5,000 years ago, centuries before the Puebloans began to use agriculture.

Early environmental impact

While the juxtaposition of the use of agriculture and local wood for cooking had altered the way the pueblos ate and prepared food, the ongoing clearing of junipers has placed an inexorable demand on the forests, researchers say, considerably reducing the number of trees.

“In this arid area, the rain tends to fall in buckets,” explains Lentz. “After hundreds of years of thinning out the root systems of trees that hold the soil in place, the rain began to wash away much of the fertile topsoil, creating an environment that has suffered continued degradation.”

Prior to the emigration of many Chaco inhabitants from the canyon, these unsustainable land use practices resulted in episodes of erosion, which reduced the resilience of the landscape and likely exacerbated the ability of the ancestral puebloans to endure the period. drought and aridity followed, says Lentz.

Current Chaco Canyon

With Chaco Canyon now declared a national park and a UNESCO World Heritage Site, visitors to the Chaco Culture National Historic Park in New Mexico can marvel at the remains of 12 grand houses and over 4,000 landmarks. archaeological interest in the rocky landscape. The structures and ruins are protected from destruction and development and declared a national monument by President Theodore Roosevelt in 1907.

Because sky-viewing is deeply rooted in the site’s past, the 34,000-acre Chaco Canyon Park was proclaimed a Dark Sky Park in 2013, a designation intended to protect it from light pollution, allowing visitors to see the stars.

“This study dramatically improved our insight into the rate and process of early environmental change through past societal consumption practices and climatic fluctuations,” says Scarborough. “This work, along with that of others, should be another red flag for what is happening more generally on our planet today.”

Researchers involved in this project:

David lentz, UC Department of Biological Sciences; Venice Slotten, University of California, Berkeley; Nicolas P. Dunning, Department of Geography and GIS at UC; John G. Jones, Archaeological Advisory Service, Tempe, Arizona; Vernon L. Scarborough, UC Department of Anthropology and Project Director; Jon paul mccool, UC and University of Valparaiso, Departments of Geography and Meteorology; Lewis A. Owen, Department of Marine, Terrestrial, and Atmospheric Sciences, North Carolina State University; Samantha fladd, University of Colorado, Boulder, Department of Anthropology; Kenneth B. Tankersley, UC Anthropology and Geology Departments; Cory J. Perfetta, UC Department of Biological Sciences; Christophe carr, UC Department of Geography; Brooke Crowley, UC Anthropology and Geology Departments and Stephen plog, University of Virginia, Department of Anthropology.

Funding was provided by the Charles Phelps Taft Research Center, the University of Cincinnati Research Council and the University of Virginia.


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