I was curious about what the first pets were (it was horses) but the answer about dogs and cats made me finally understand how when living with a dog its like you're a team, but when living with a cat they are pretty indifferent. Dogs and humans were both the top of the food chain, the dogs were attracted to the waste from human settlements. They became domesticated out of a mutual beneficial relationship. They spent many generations as two species living together as hunting equals before being master/pet once that became no longer necessary so evolution made the matchup better. Cats on the other hand were wild animals who were attracted to mice which bred in the hay beds of domestic sheep. Humans fed them because they were cute and kept the rodent population down in the barns. That's why they are more wild seeming. Thought it was interesting enough to share I then started to wonder if an alien worlds, would advanced aliens have pets that were once former fellow predators, or adopted like the cat, or both?