Lemurs have gotten a bad rap for years. Like humans and animals, they’re primates. But for years scientists have assumed they’re basically pretty stupid: Friendly and social, but dumb. Duke University professor Elizabeth Brannon decided to test this thesis by offering the lemurs a computer test: If they could complete a pattern on a touch-screen, they’d get a sugar-pellet treat.

Whaddya know? They all started lining up and completing really complex patterns. As a story in Reuters notes:

Although lemurs are social, they would often stop what they were doing to play on the computer.

“Occasionally, one animal would come over and finish the sequence started by another to get the reward,” said Brannon.

It appears that lemurs are indeed able to count — it’s just that normally they couldn’t be bothered. But dangle a couple of sugar pellets in front of ‘em and hell, they’ll learn calculus. As Brannon notes, this may help explain how human intelligence evolved; at some point in the distant past, homo sapiens might have hit upon the sweet spot of challenge-and-reward that got our brains to wake up and start inventing fire, tools, and Melrose Place.