The animals that we keep as pets are domesticated. The dogs that we have today started as wolves but we’ve bred selectively, in part for their friendly disposition towards humans. In the case of dogs, this process took thousands of years. It’s possible that we could domesticate a bear but it wouldn’t happen by simply training a bear as they currently exist. We would have to breed a bear that has a disposition to be a pet. A bears/lion/wolf’s instinct is to be a territorial predator. They are not psychologically inclined to be obedient to a human, which is why keeping they as pets doesn’t usually end well.
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