can you think of an ethical principal that would prohibit the killing, hurting, sacrificing, or eating of humans for the sake of other ends that would not equally pertain to animals?

There is two justification for this ethical principle:

Comparative justification:

This is an oft-cited justification for the consumption of animal meat. When there is a question arisen about why an animal eating is morally justified then the opinion given that comparison between humans eating animals and animals eating animals. Often we could not base our moral judgments regarding the acceptability of certain actions.

Dominion based justification:

This justification goes with the men eating have slightly considered depending on the wider look for the world.