I read an article this Sunday from the Chicago Trib, but can't find it online. I've posted a link to an article that suggests the similar findings of the Trib article. Basically, in a nutshell, scientists have discovered that rats experience joy and laughter when tickled, and come to anticipate it like a child does.
Here's the link:
http://abcnews.go.com/Technology/story?id=626264&page=1Granted, the idea of lab rats turns my stomach. Believe what you will about scientific advances made at the highest price to lab animals, I'm not swallowing that one, due to the many alternatives that exist. However, from this study, I've learned that the common rat shares a very human emotion, if you will...joy.
So, let me see if I have this correct...
Science has proven that cows and pigs suffer from stress and anxiety. Check.
Science has proven that dogs can count and problem solve. Check.
Science has proven that elephants love, mourn and grieve. Check.
Science has proven that rats, among other animals, experience joy. Check.
But hey, they're only animals, lacking common human thoughts and emotions, which puts them so far beneath us that we can abuse them as we see fit. Right? Got it.