We are horrible to each other, so it really shouldn't come as a surprise that humans are often incredibly cruel to animals. It shouldn't............but somehow, it still does. Seven gorillas were killed in cold blood in an African wildlife preserve for absolutely no reason whatsoever: http://ngm.nationalgeographic.com/2008/07/virunga/jenkins-text/1.
Why? What could possibly motivate a person to do something like this to innocent animals? What the hell is wrong with us?