As the morning sun dips through the trees, Rodger Kram prepares for the marathon. But not the race before, as it was running.
Kram, a physiologist at the University of Colorado Boulder, stood next to James Wilson at the end of a country road. Each had a nylon belt around his head. In fact, straps attached – called tumplines – rested on a transverse beam across the two lower backs.
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It was worth going on a 20-mile hike to replicate how the ancient people of Chaco Canyon transported wood around 1,000 years ago (SN: 5/17/17). At the end of the day, a successful trip suggested that it would take a few days for the two men to take the logs to Chaco, Kram, Wilson and colleagues on February 22. Journal of Archaeological Science: Reports.
Located in the northern corner of New Mexico, Chaco Canyon is home to large structures built between AD 850 and 1200. The multistory stone buildings called large houses had roofs with wooden beams about 5 meters long and 22 centimeters in diameter. The site contained at least 200,000 logs of this size.
The forest was more than 75 kilometers away from the forest.SN: 9/26/01). Animals and laden wheels did not exist at that time, nor do they seem to have been drawn by beams. Scientists are concerned about how ancient people, the ancestors of the modern Diné and Pueblo people, moved the large logs.
A 1986 study suggested that each beam had a mass of 275 kilograms. But this number Kram could not have guessed correctly.
In 2016, a section of a tree outside his house – a heavy pine, the same species used in Chaco – and weighed in his bathroom. He then extrapolated that a 5 meter long piece of wood would be closer to 90 kilograms. This revelation led to a 2022 study estimating that Chaco Canyon logs weighed between 85 and 140 kilograms.
“As soon as we indicated that the weight was reasonable, I wanted to carry them,” says Kram.
He and Wilson speculated that the culverts could have been used to transport wood. These headbands have been found inhabited on every continent and are thought to have been used by him at least about two thousand years ago. They were still widely used to carry heavy loads, like professional porters in Nepal. Tumpline is placed on the top of the head – in the line of the cervical spine – with a small load placed on the back.
While it is not clear that the Chaco people hauled logs for wood, there is evidence that they hauled other things, such as water containers.
To see if the transportation of the tumpline logs could be done humanely, Kram and Wilson trained for three months in the summer of 2020, gradually increasing the weight and time of the walk. The strangers passing by could not hide their confusion.
On the last day, the team walked twenty kilometers carrying heavy pine that had been air-dried, which is how the Chaco people prepared firewood. It was 60 kilograms, 2.5 meters long and 24 centimeters in diameter. The whole trip took about 10 hours, and the weight of the full materials slowed the two paces down a bit.
“I felt happy at the end that it was doable, and that the 132-pound log shared our necks,” said Wilson, now a medical student at the University of Colorado School of Medicine in Aurora. But “we never really doubted that we could do it.”
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