This seems like a very intuitive conclusion to me. One of my long-term pet-sitting clients was a young male yellow lab/German Shorthaired Pointer mix who was physically very playful and had a very evident sense of humor. I showed up one day to water the plants outside his house, and was wearing my big white sunhat. He immediately spotted it and, every time I leaned down to grab the hose or adjust a flowerpot, he would swipe it off my head and run off with it, looking back over his shoulder at me with this unmistakeable twinkle in his eye, challenging me to chase him and get it back. When I did, he easily outmaneuvered me in this neverending game of "dodge the slow human," and I could tell he was laughing at me. From livescience.com:
Studies by various groups suggest monkeys, dogs and even rats love a good laugh. People, meanwhile, have been laughing since before they could talk.
"Indeed, neural circuits for laughter exist in very ancient regions of the brain, and ancestral forms of play and laughter existed in other animals eons before we humans came along with our 'ha-ha-has' and verbal repartee," says Jaak Panksepp, a neuroscientist at Bowling Green State University.
When chimps play and chase each other, they pant in a manner that is strikingly like human laughter, Panksepp writes in the April 1 issue of the journal Science. Dogs have a similar response.
Rats chirp while they play, again in a way that resembles our giggles. Panksepp found in a previous study that when rats are playfully tickled, they chirp and bond socially with their human tickler. And they seem to like it, seeking to be tickled more. Apparently joyful rats also preferred to hang out with other chirpers.
"Although some still regard laughter as a uniquely human trait, honed in the Pleistocene, the joke’s on them."