On Facebook, today, I saw a video of a man freeing a mountain lion (that’s a big animal) from a steel trap. First he had to get the animal’s head in a noose on a pole, which he used to keep the animal’s jaws and front claws away while he opened the jaws of the trap. Then he had to jump back and release the lion.
But the lion didn’t turn on him. There seems to be some kind of gratitude instilled in the lower animals by the Creator (who else?) that makes them recognize some personal services, a part of the mystery of life.
Would all humans do similar deeds, as return a personal service? Not always. Humans have free will, able to choose evil.