Humans Abandoned a Bison-Hunting Site Around 1,100 Years Ago — Turns Out, Climate Change Was to Blame
Bison hunters had frequented the Bergstrom site for hundreds of years. But about 1,100 years ago, they left the area and all its bison behind.
Now, a new study in Frontiers in conservation science solved the mystery of the strange abandonment of the site. According to the study authors, the region – smack in the middle of Montana – was deserted when severe droughts dried up its water supplies, suggesting that climate change, combined with changing social and economic dynamics, caused bison hunters to change when, where and how they hunted.
“We found that bison hunters stopped using a killing site in central Montana about 1,100 years ago,” paleoecologist John Wendt, study author and assistant professor at New Mexico State University, said in a news release. “It appears that hunters stopped using it because severe and recurring droughts reduced the water available for animal treatment in a small nearby stream. Abandonment of the site was a response to environmental stressors and changing social and economic pressures.”
Learn more: Humans settled in North America 16,000 years ago, ready to hunt
Hunting herds at Bergstrom
In the late 1800s, hunting brought bison to the brink of extinction in Montana and beyond. But around 2,000 years ago, bison hunters roamed the region, employing a multitude of hunting strategies and sites to hunt the herds sustainably.
The team excavated artifacts throughout the site and analyzed them along with the contents of two sediment cores.
(Image credit: Michael Neeley)
However, how these hunters made their decisions, including their decision to desert the Bergstrom site, where bison thrived long after human hunting ceased, remained up in the air. “The Bergstrom site presented a conundrum because it was used intermittently and abandoned when bison were common throughout the region and hunting was intense,” Wendt said in the release. “Why would hunters stop using a site that has been operating for so long?
To solve this mystery, the study authors analyzed artifacts from Bergstrom, as well as charcoal and pollen fragments extracted from two sediment cores taken from the site. By combining these results with reconstructions of bison populations and climatic conditions around Bergstrom, the team determined what changes contributed to the site’s decline.
“The abandonment was not because the site had become ecologically unsuitable in any absolute sense. The bison were still there, the vegetation had not changed, and there was no substantial change in fire activity,” Wendt said in the release. “The business of bison hunting was not simply about tracking prey populations.”
Learn more: 13,000-year-old campsite reveals ancient humans’ hunting patterns
Site exchange, from small to large
The study’s authors say the decline in activity at the site instead coincided with a series of severe droughts, which reduced water availability and the site’s usefulness to hunters, who used the water to process bison. At the same time, the team found, the simultaneous increase in food demand and food surpluses led hunters to congregate in larger, less mobile groups, which stayed at sites larger than Bergstrom and stayed longer.
The excavated artifacts were recorded and analyzed, and the charcoal fragments were evaluated by radiocarbon dating.
(Image credit: Michael Neeley)
“These larger operations were based on significant culls and could produce surpluses for trade and winter storage,” Wendt said in the release. “But it also meant greater reliance on specific resources like water, fodder for large herds and fuel to put out fires. »
While severe droughts made Bergstrom less useful to hunters, larger, resource-rich sites saw an increase in utility after the smaller site was abandoned. In fact, although the study’s authors say hunters may have stopped at Bergstrom after its initial desertion, occupying the area for short periods leaving little evidence of human hunting, the site saw less activity than those equipped with the resources to support larger hunting operations.
Despite his decline, Bergstrom was important. The site was frequented for approximately 700 years before falling into disuse, and although the study authors were unable to determine the frequency and duration of its individual occupations, the site still demonstrates that hunters were using an adaptive approach to hunting bison approximately 1,100 years ago.
“While people have been adapting to climate for much longer,” Wendt said in the release, “the abandonment of Bergstrom shows that people have reorganized in response to recurring droughts over the past 2,000 years.”
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