Apes and birds have long been known to demonstrate their intelligence by pulling a string to access food, but now researchers at Queen Mary University of London (QMUL) have discovered that bumblebees can also learn the skill. Not only is this the first time insects have been seen to use this kind of strategy, but the trained bees also spread the ability throughout the colony, prompting questions about social learning, culture and intelligence in animals.

The researchers began with three artificial flowers containing sugar water and attached to pieces of spring. These were placed under a clear Plexiglas panel with the strings poking out, to test whether the bees could work out how to solve the puzzle and get to the prize. Out of a control group of 110, only two bees figured it out with no training at all.

A second group was trained by gradually moving the flowers further and further out of reach each time, and in this case, 23 out of 40 learned to pull the string to get to the reward. When new bees were introduced, 60 percent of them managed to pick up the skill simply by observing the trained bees. And after they were introduced into colonies, the new skill was successfully passed through a large part of the population and down several generations.

"We found that when the appropriate social and ecological conditions are present, culture can be mediated by the use of a combination of simple forms of learning," says Sylvain Alem, lead author of the study. "Thus, cultural transmission does not require the high cognitive sophistication specific to humans, nor is it a distinctive feature of humans."

This isn't the first time bees have demonstrated more intelligence than they might usually be given credit for. An earlier QMUL study showed that bees were reasonably quick to figure out the shortest paths between flowers through trial and error, a behavior previously thought beyond the capabilities of their simple brains. The findings may also help scientists develop a better understanding of how humans managed to evolve such advanced systems of social learning and culture.

"We are ultimately interested in finding out what might be possible neural solutions to underpin such refined skills in bees," says Lars Chittka, the project supervisor. "How can they do it with such small brains, and how can their miniature nervous systems manage such a diversity of behaviors and cognitive tasks? We are exploring this through modeling information processing in parts of the insect brain, and we find that often, exceedingly difficult tasks, for example in visual pattern recognition or floral scent learning, can be solved with extremely simple neural circuits. We are still a long way from understanding the required neural circuitry for string-pulling, however."

The research was published in the journal PLOS Biology. You can watch a bee demonstrate its newfound skill in the video below (courtesy of Sylvain Alem).