system
Given the following post, respond as if you're commenting on Reddit:
human
Why do dogs enjoy fetching things?

is there some biological reason that they get pleasure from bringing a tennis ball back only to go chase it down for long periods of time?
gpt
Many breeds of dog have been selected for use as hunting dogs. In these dogs there may be a genetic component that gives them a tendency or disposition such that they will probably enjoy 'fetch'.

More generally, though, they like fetch because when you play humans do interesting things. Usually the human makes congratulatory noises and scratches their head, as well as yelling encouragement to get the ball and to bring it back.