Bison shed light on big wipeout
"big wipeout" refers to the population crash and (largely) extinction of megafauna in North America. New mitochondrial DNA studies in bison suggest that the crash began before humans crossed the Bering Strait, and therefore human hunting was not the primary cause of extinction.
The fall in numbers coincides with a warm period in which the steppe tundra that bison like was covered by forests. These forests may have acted as a barrier to bison dispersal and would have provided few sources of food.
This warm period was followed by cold, arid conditions.
"Some component of these ecological changes may have been sufficient to stress bison populations across Beringia," the researchers write in their research paper.
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