10 Surprising Behaviors in Nonhuman Animals

That's actually a kangaroo rat. Those huge cheek pouches are good for taking food or nest material back to its burrow. Are they good for laughter, too? Bob Landry/Time & Life Pictures/Getty Images

Nobody has to tell us that animals can be funny: from dogs chasing their tails to potty-mouthed parrots, we know that animals can make us laugh. But did you know that animals themselves laugh?

When researchers at the University of Washington discovered that rats make a high-pitched, ultrasonic chirping noise, they initially weren't sure what it communicated. But a flash of inspiration led one of the scientists to, well, tickle his test subjects. And indeed, it appeared that rats showed the same biological response as humans when confronted by the Tickle Monster: peals of giggles.

But laughing, of course, doesn't prove a sense of humor. So when researchers witness chimps playing peekaboo, they have a little more solid evidence of animals that don't just laugh but understand how to make others laugh. And then there's the story of the gorilla that got his kicks by running beside his trainer, along the length of his cage, at full speed. The gorilla would suddenly stop and laugh uproariously as the human kept running past him, seemingly delighted to find a Stupid Human Trick [source: Santa Maria].

Sure, it's not exactly Louis C.K. material. But better than Dane Cook?