I left a hamster wheel out in the woods to see what would happen
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Because Michael mention this thing at [0] at 18:12 or so.
Cats, rodents, ferrets, anything capable of running fast would enjoy this. Humans too if we could hop on and off without breaking any bones
We also have treadmills and stair masters with a similar concept of infinite running or climbing, but they are not nearly as attractive to humans as wheels are to rodents.