Lars Chittka didn’t expect much when he decided to see if bumblebees could learn to pull a string for a reward. While animals from birds to apes can solve this puzzle, it seemed unlikely that bees could solve it too because they have such tiny brains.
“I asked what may have seemed an entirely mad question,” says Chittka, a behavioral ecologist at Queen Mary University of London.
But it turned out not be mad in the slightest. In new research reported in PLOS Biology, Chittka and his colleagues got a “big surprise”: they found that bumblebees could easily be trained to pull strings for sugar water.
First the researchers attached strings to blue discs with sugar water in the middle, and then let the bees learn that these fake flowers held a reward. The next step was putting the flowers under plexiglass – only the very tips of the strings were within reach. This was the first test of string pulling in an insect.
With this training, more than half of the bees solved the puzzle, vigorously pulling the string toward them until they could drink the sweet reward in the flower. Another experiment showed that while untrained bees rarely learned this skill on their own, a few actually did. “This was even more of a surprise,” Chittka says.
The researchers also found that this new skill spread socially and culturally from bee to bee. After watching trained bees demonstrate their string-pulling prowess, 60 percent of untrained bees solved the problem on their own. And adding a single trained bee to a colony of untrained bees was enough for many of them to acquire the skill.
“This was the final surprise – there is still a common perception that humans, and especially the cultural processes seen in humans, are unique in their cognitive performances,” Chittka says. “It’s tempting to assume that a large brain is a prerequisite for such phenomena.” But, as his work shows, problem solving and cultural transmission don’t necessarily take much brainpower.
Besides enjoying the insights from his work, Chittka relishes the “sheer absurdity” of watching bees solve the string-pulling puzzle. “When I first saw it, I just couldn’t believe what I was seeing,” he says. “Even now, looking at the videos still makes me laugh.”
Research Article: Alem S, Perry CJ, Zhu X, Loukola OJ, Ingraham T, Søvik E, et al. (2016) Associative Mechanisms Allow for Social Learning and Cultural Transmission of String Pulling in an Insect. PLoS Biol 14(10): e1002564. doi:10.1371/journal.pbio.1002564
Image Credit: Sylvain Alem