Scientists don't know exactly why rats are so fond of playing hide-and-seek.
But, as a research paper published this week in the journal Science suggests, they really get into it — and they don't do it strictly for food rewards.
In perhaps the happiest case of testing on rats ever, German neuroscientists spent weeks teaching rats how to play hide-and-seek in large room with boxes. And before long, the playful rodents were taking turns with the humans, finding a spot and waiting to be found.
With each passing day, they grew savvier at the game, often doubling back to check spots that researchers had used for cover in a previous game. They also figured out that transparent boxes were terrible hiding spots, opting instead for those that you couldn't see through.
According to The Atlantic, all six of the rats learned how to seek. But one rat — there's always one in the game — either couldn't figure out how to hide, or refused outright.
And what was their reward for playing? When they found a human, they were tickled, caressed and stroked. Good rat.
For the scientists, it was about studying play behavior in animals, a vital evolutionary trait in all mammals.
For the rats, it was pure, uninhibited joy.
"It's rare in neuroscience to see rats that are so engaged in a task," study co-author Juan Ignacio Sanguinetti-Scheck tells The Atlantic. "I've never seen a rat run so much in a lab."
Indeed, they practically bubbled over with elation every time they found their human. In fact, researchers recorded their shrieks of glee — a sound so high in pitch, it can't be heard by the naked human ear. Even more adorably, the test subjects leapt in the air whenever they sniffed out a scientist.
Yes, they literally jumped for joy.
And even when researchers offered food as an end-game reward, the rats held off on accepting it. They seemed to want to keep playing the game.
So why do rats take so readily to hide and seek?
"When you work a lot with rats over the years, you see how intelligent these animals are, and how social," study co-author Konstantin Hartmann of Berlin's Humboldt University tells The Guardian.
Hide-and-seek may require rats to do what they love doing — using their brains and having fun with friends, even those of the non-rodent kind.
But let's face it, hiding may also be in their genes.
After all, oft-persecuted rodents have to live their lives among humans, building their entire ecosystem alongside ours. Spot a rat? Call pest control. They'll truck in a chemical arsenal that would make the Geneva Protocol blush.
And, of course, when a deadly disease breaks out among humans — like say, the Black Plague — rats invariably take the fall for it. Never mind that research proves they were terribly miscast in the role of medieval villain.
Rats deserve better. We know they're sensitive and inquisitive, leading complex social lives and forming strong bonds with each other. Prick them with a needle and they bleed. And yes, if you tickle them, they will laugh.
Besides, who wouldn't want to play hide-and-seek with a rat?
It sounds like much more fun than the same, deadly game we've been playing with them for centuries — the one where they hide. And we scream.