//So do you think that there is a moral instinct within us, or are we just obeying a law, like a speed limit?//
Mammals with long incubation periods and difficulties in childbirth (e.g. US) wouldn't have lasted without the instinct to care for the motherapproaching and at the moment of parturition.
Mammals who need to hunt when there's not much to gather will not as individual families do very well when their food supply has four legs, can run faster and has a powerful kick. That's why our ancestors formed packs in order to act collaboratively.