Laughter is one trait that is strongly associated with being human. However, we now know that we're not the only ones who can appreciate a good laugh. Scientists have long known that, when playing, rats emit noises that sound like laughter, but whether the noise truly was laughter was not determined right away.
To get to the bottom of things, rats were tickled. That's right-- bunch of scientists tickled some rats, for science!
The researchers used an instrument known as a transducer to bring the high-pitched sounds to a level of frequency that could be heard by humans. They then concluded that the vocal activity was indeed laughter.
To give further credence to their findings, the rats started to enjoy the company of humans, playing, and following hands for fun--all indications that the rats were truly enjoying themselves. Like us, they, too, apparently like to express their joy vocally.
Again, most people don't think too highly of rats as a species. But knowing that they share our capacity for laughing does seem to make them a little more endearing.
