For researchers, the question is no joke:
Marc Bekoff, University of Colorado–Boulder professor of ecology and evolutionary biology and author of The Emotional Lives of Animals, believes [animals do have a funny bone]. In fact, he thinks we’re on the cusp of discovering that many animals have a sense of humor, maybe even all mammals. The idea that animals can appreciate comedy isn’t as far-fetched as it sounds, considering some of the other groundbreaking discoveries scientists like Bekoff are making about animal behavior: They have found dogs that understand unfairness, spiders that display different temperaments, and bees that can be trained to be pessimistic.
As Bekoff points out, Darwin argued that the difference between human and animal intelligence is a matter of degree, not of kind. Or as Bekoff put it, “If we have a sense of humor, then nonhuman animals should have a sense of humor, too.”
A similar sentiment inspired psychologist Jaak Panksepp to enter his lab at Bowling Green State University in Ohio one day in 1997 and tell undergrad Jeffrey Burgdorf, “Let’s go tickle some rats.” The lab had already discovered that its rats would emit unique ultrasonic chirps in the 50 kilohertz range when they were chasing one another and engaging in play fighting. Now the researchers wondered if they could prompt this chirping through tickling. Sure enough, when the researchers began poking at the bellies of the rats in their lab, their ultrasonic recording devices picked up the same 50 kilohertz sounds. The rats eagerly chased their fingers for more. Soon, as the news media trumpeted the existence of rat laughter, people the world over were opening up their rat cages and engaging Pinky and Mr. Pickles in full-scale tickle wars.
The Dish 