You watch one video of rats playing hide-and-seek on YouTube, and you're hooked. That's what happened to Michael Brecht, a neuroscientist at the Humboldt University of Berlin. And thus, a research project was born.

Journalist, naturalist and Boston Public Radio contributor Sy Montgomery said the research proves this wasn't an anthropomorphic phenomenon: rats really do love to play.

"He set up this 30 square meter play room which is pretty big, with all kinds of cardboard shelters, boxes, made from plastic you could see through, and plastic you couldn't see through. There were seven hiding places for the rats, and three hiding places for the designated game master," she said. "When the rat was the seeker, the game master would close the box and he would hide, so the rat came to understand the cue to leap out of the box and go looking for the game master was this opening the lid, and when the rat was the hider he'd leave the box open and crouch beside it, while a rat jumped out and scurried to one of the hiding places. They learned to do it in a couple of weeks."

Montgomery said this research — as playful as it is — indicates rats are intelligent and empathetic beings.

"Rats play, and if you've ever known a rat well, you know that they do love to play, and play is something associated with a higher mind," she said. "But also play hide and seek you need this cognitive ability or capacity called theory of mind, to imagine what someone else might be thinking."