Morality is for children. They need rules, laws, codes and commandments to make them behave, and the crushing reality of herd mechanics when they don’t. Adults don’t need any of that. Human Children are artificial creatures and Human Adults are authentic creatures, and this is one of the ways that that comes out. 

The Golden Rule is an example of a manmade moral construct. It sounds pretty reasonable as rules of thumb go, almost utopian, but this rule does not occur in nature where mothers don’t die for their children, no one takes a bullet for a buddy, and no one stays back to cover their friends’ escape.

We’re all cannibals, it’s just seldom called for.