Dogs were instrumental in early human survival and they’ve benefited for it. There’s almost a billion dogs in the world, but only a quarter million wolves. So in a natural selective sense that was a good move wolves made by becoming companions with humans.

Behavior has been bred into dogs going way back to the beginning. Fetch is one of those behaviors. I recently watched a documentary that showed the unique interaction of dogs with humans. Dogs are really good at understanding human body language. For example you can point at something and a dog will cue on it. No other animals reliably respond to that gesture, even chimpanzees which are genetically closest to us.