The conversation between human and AI assistant.
[|Human|] Based on the input, formulate a hypothesis regarding the past.
[|AI|] One possible hypothesis for the sharp decline of the population of American bison in the 1800s is that there may have been an increase in hunting and commercial exploitation of bison during that time period, leading to a decrease in their numbers.
[|Human|] 
Based on the input, formulate a hypothesis regarding the past.