Thank you for this very informative and important article. It certainly was an interesting read.
I'm not sure what the answer to that question might be. But there surely isn't much of differences between humans and those other species. And I'd definitely advocate treating all creatures respectfully.

I'd like to draw attention to the "learned aggressive behavior" aspect of this subject. Dr.Robert Sapolsky have done and published some work about a group of baboons and how events led to a complete change of the population's behavior and tendencies for aggression.

Here's a short Youtube vid that I quickly found, if you're interested in hearing that story (not the best, but the others are in longer vids/lectures)

He has many other interesting lectures and stuff related to chimps, bonobos, baboons,and humans.