- Harris CR & C Prouvost 2014 Jealousy in dogs. PLoS One 9(7):e94597. (pdf)
To a non-scientist, it seems ridiculous for somebody to be going to the effort of "proving" that dogs can display jealous. Maybe the grant didn't get funded, and you had a few dogs around, so what the heck - what else is there to do?
But this isn't silliness. Dr Robert Sapolsky at Stanford has made a fascinating career out of studies of the role of behavior and neurobiology in evolution of animals. (If you've never heard of Dr Sapolsky, take a few minutes out of your day and watch one of his always-enjoyable-and-fascinating lectures, of which there are many online. And here's one, at a TED conference; skip past the boring provost...). And it's the larger, evolutionary context of behavior that this study is about. So the question is not just "Can dogs be jealous?", but the even more interesting one - "why?".
It's easy to understand why a dog might want the bone that's in the mouth of another dog. But why should a dog be jealous if its owner is scratching another dog on the head? The hypothesis is that the relationship of the dog with its owner is valuable, and the dog should have an interest in protecting it. So if you were the dog, we might expect you to start getting a little nervous when there's another dog getting too cuddly with the hand that feeds thee. How do you respond to this? Attack? Act coy and non-chalant? Worm your way into position to get some head scratches yourself? And should you only be jealous of other dogs? What about other human distractions that keep you from being the center of attention? (Do dogs hate smart phones?). When you're unhappy about another dog getting too much attention, do you wag your tail more to the left than the right? (A study has shown that dogs wag more to the right when they're happy about something.)
Some interesting stuff here...