As a former dog owner and dog lover, I was not really surprised by last week's report that dogs have been found to "sense inequity", a.k.a. be jealous of the dog that's being treated better than they are.

Scientists did a very simple experiment- they asked two side-by-side dogs to perform a trick, then only rewarded one of the dogs with a treat.  Who wouldn't be jealous of that?  Eventually the non-rewarded dogs stopped doing the trick (smart dogs!). 

The cool thing is that this is the first time this has been seen in non-primates.   I would expect that if we looked closely at other non-primates, we might find similar behavior.  Dolphins?  Cuttlefish?  Some of the "smarter" marine animals that have been shown to display other interesting behaviors might be just as jealous as Fido! (side note: on my Marine Science class's trip to the Baltimore Aquarium last week, the educator leading our squid dissection shared that their octopus is trained to climb into a laundry basket [so she can be weighed], and she also likes to play with Mr. Potato Head- they hide food in the backside flap, and the octopus has figured out how to open it and get the food.)

For my science fair students: if you click on the first link to the dog study, you can see that this experiment is a nice example of a simple experimental design including several controls!