Based on recent research, Alan Sullivan, archaeologist at the University of Cincinnati, has revealed the secret to how the ancient peoples of the Southwestern United States, ancestors of the modern Pueblo people, survived the arid climates.
     Previous research on the topic revolved around the idea of these people living off corn crops, despite a relatively low amount of evidence, and much of the soil being unsuitable for cultivating these crops. However, the ground in the Coconino Rim was covered in Chenopodium, more commonly known as goosefoot, months after a fire last year. These growths came before other old-growth forests and may point towards a possible food source for these early native societies.
     This was further supported by decades of research that included meticulous excavation and analysis. From this research, Sullivan suggested that the natives used fires as a form of firing, clearing out juniper and pinyon trees, quickly being followed by ruderals that were high in nutrition. All of this could sustain the peoples before moving onto another area that could be planted and harvested by using small fires.
     The center of the research is in and around the Grand Canyon, including the Kaibab National Forest where Sullivan and his colleagues began to research how corn could be used as a sustainable food source in northern Arizona. Sadly, little evidence of corn appeared in the layer of earth and parts of the soil indicated regular fires.
     Sullivan has published about a dozen papers assessing the presence of maize at nearly 2,000 sites that show human settlement from centuries ago, to little avail. However, from this work it was possible to see that few grains of pollen are found on the site, instead there is evidence of burning traces around the settlements, representing many small fires, with the oldest juniper trees and ponderosa pines showing no burn scars. There was also a heavy concentration of edible plants in the layers contemporary with human activities, which dropped off swiftly following the abandonment of the same sites.
     "It's not based on wild speculation. It's evidence-based theorizing. It has taken us about 30 years to get to the point where we can confidently conclude this," said Sullivan.
     Neil Weintraub, archaeologist for Kaibab National Forest, was the person who first noted the ruderals growing following the aforementioned fired and relayed the results to Sullivan. He also suggested that the nomadic lifestyle of the Puebloans would lend itself to the fire farming. "It's a fascinating idea because we really see that these people were highly mobile," said Weintraub. "On the margins where it's very dry we think they were taking advantage of different parts of the landscape at different times of the year."

Edited from Laboratory Equipment (30 November 2017)