Food may be scarce at Chaco Canyon

According to new research, Chaco Canyon, a once-essential site for pre-colonial peoples called Anasazi, may not have been able to produce enough food to support thousands of residents. The results could cast doubt on the approximate number of people who can live in the region all year round.

Located in the Chaco National Historic Culture Park in New Mexico, Chaco Canyon is home to many small homes and a handful of multi-story buildings called Big Houses. Based on these structures, researchers believe that the metropolis was once a bustling city that housed up to 2,300 people at its peak of 1050 to 1130 AD.

But Chaco is also in a ruthless environment, with cold winters, hot summers and little rain, whatever the season.

"You have this place in the middle of the San Juan Basin, which is not very livable," said Larry Benson, assistant curator of the Natural History Museum of the United Kingdom.

Benson and his colleagues have recently discovered an additional problem regarding the relevance of the region. The team conducted a detailed analysis of the climate and hydrology of the Chaco Canyon and found that its soil could not have supported the agriculture needed to feed such a flourishing population.

The findings, says Benson, could change the way researchers view the economics and culture of this important area.

"You can not cultivate drylands," said Benson. "There is not enough rain."

Today, Chaco Canyon receives only nine inches of rain each year and historical tree ring data suggest that the climate was not much wetter in the past.

Benson, a retired geochemist and paleoclimatologist who has spent most of his career working for the US Geological Survey, has made an effort to better understand if such conditions could have limited the number of people who can live in the canyon. . In his recent study, Ohio State University archaeologist Deanna Grimstead collected a wide range of data to explore where Chaco Canyon residents may have grown corn, a staple for most of the Pueblo ancestral peoples.

They discovered that these precolonial farmers not only struggled against poor rains, but also with sudden destructive floods that swept through the bottom of the canyon valley.

"If you are lucky enough to have a spring spring that will wet the soil before planting, about three quarters of the time, you will get a summer flow that will destroy your crops," said Benson.

The team calculated that the inhabitants of Chaco could have, at most, exploited only 100 acres of Chaco Canyon's soil. Even though they were exploiting all the surrounding side valleys – a monumental feat – they would still have produced enough corn to feed just over 1,000 people.

Researchers also went a step further to find out if former Chaco residents could have supplemented this lack of food with wild game such as deer and rabbit. They calculated that providing the required 185,000 pounds of protein to 2,300 people would have quickly eliminated all small mammals in the area.

In short, there would have been a lot of hungry mouths in Chaco Canyon. Benson and Grimstead published their results this summer in the Journal of Archaeological Science.

For Benson, this leaves two possibilities. The people of Chaco Canyon have either imported most of their food from the surrounding areas, or the canyon dwellings have never been permanently occupied, serving rather as temporary shelters for regular pilgrimages.

One or the other scenario would involve a massive movement of people and property. Benson estimates that importing enough corn and meat to feed 2,300 people would have forced porters to make 18,000 comings and goings in Chaco Canyon, all on foot.

"Whether people bring corn to feed 2,300 residents or that several thousand visitors bring their own corn to eat, they do not get it at Chaco Canyon," Benson said.