Lemurs, once believed to be cute but basically stupid, show startling intelligence when given a chance to win treats by playing a computer game, U.S. researchers reported Wednesday.
The study will help shed light on how humans became sophisticated mathematically, the Duke University team said.
So far, it suggests primitive animals such as lemurs need a good reason, such as a treat, to bother trying to count. Humans and monkeys, in contrast, will stretch their minds simply out of curiosity.
Lemurs are primates, as are monkeys, apes and humans. But they are considered far less intelligent. “The little bit of research that’s out there suggests their learning capacities are not as sophisticated as those of monkeys,” said psychologist Elizabeth Brannon, who led the research.
“So initially, I thought it very unlikely that I was going to get any cognitive experiments to really work with them.”
But she found a combination of greed and the lure of a touch-screen computer worked to get the long-tailed animals to cooperate.
“If a task involves a food reward, they can be amazing,” she said. “They’ll work for a couple of hundred trials because they want these sugar pellets, even though we do not deprive them of food in any way.”
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.
Unexpectedly, the lemurs could remember sequences. For instance, they showed they could remember the order of appearance of random images by touching them in order when they reappeared as a group.
“It shows that the animal is actually learning some kind of strategy above and beyond what they’re learning about the individual pictures in a given set,” Brannon said.
But the lemurs were not especially dexterous. “While monkeys will use their fingers, the ringtails (lemurs) use their nose or mouth to touch the screen, sometimes kind of kissing it,” Brannon said.