They say a picture is worth a 1000 words. Well, this video of a grizzly bear cub playing with a wolf pup - an odd couple - is worth countless words. There's much interest in "odd couples", individuals of different species who form close social bonds that are rather unexpected. While a grizzly playing with a wolf is rather unexpected, these two individuals were young and in captivity and play is as natural to young animals as is breathing.
Come play with me: The rules of engagement of fair play
What's very interesting in this video from an ethological (animal behavior) perspective is not only do these youngsters play in a thoroughly friendly and fair manner, but they also use many of the same play signals to communicate messages such as "I want to play with you". These include the "bow" - they quickly crouch on their forelimbs and stick their butts into the air and then approach their playmate or approach and then rapidly run away - and what's called "exaggerated pawing" or "paw slapping", gentle enough so as not to scare off their friend, while still communicating their intention to play. These "universal play signals" are shared among members of a wide variety of species (see also and and and). There also some vocalizations, what people call "play panting", that are also a typical part of the relaxed and contagious atmosphere of play.