Bumblebees can use tools to solve a problem, according to experiments that demonstrate their remarkably advanced cognitive abilities.
The bees were given an adapted version of an experiment that, 100 years ago, first demonstrated chimpanzees could work out how to retrieve an out-of-reach banana by stacking boxes. Since then, various other primates, elephants and crows have joined an elite cohort of species known to be capable of this level of insight and spontaneous problem solving.
In the latest research, bees were shown to be able to roll a polystyrene ball to a specific location and climb on to it in order to access an artificial flower on a low ceiling. The findings challenge the longstanding assumption that insects operate purely on instinct and mindless trial-and-error learning.
“Most people think insects are reflex-based machines,” said Dr Olli Loukola, a behavioural ecologist at the University of Oulu, Finland, and senior author. “That they can’t have any emotional states or feel pain. Some people don’t even realise that they have brains. I hope that these results change the worldview about that.”
The bees, which were only a couple of weeks old, were first trained to associate a blue artificial flower with a reward of sugar water. During the test, the flower was moved to the ceiling of a transparent petri dish-style chamber whose ceiling was too high for them to reach, but with insufficient space for them to hover. A ball was also introduced into the chamber. To reach the flower, the bee had to roll the ball under it and climb on top – a behavioural sequence they had never previously encountered or been trained to perform.
In the most basic version of the test, 75% of the bees were successful in reaching the flower. “This is essentially an insect version of the classic ‘box-and-banana’ problem,” said Loukola. “The animal must realise that an object can be repositioned and then used as a tool to reach an otherwise inaccessible goal. What stands out about the result is that this kind of spontaneous problem solving is now demonstrated in an insect.”
A question remained, however, about whether the bees were really solving the problem. An alternative possibility was that the bees simply enjoyed the sensation of rolling a ball along and – separately – were attracted towards the blue dot, meaning that they fortuitously ended up positioning the ball in the right spot.
To test this, the scientists put the bees through increasingly complex versions of the challenge. In the final setup, the bees were allowed to explore a left and right chamber, one of which featured the artificial flower, before the ball was introduced. The scientists then illuminated the chamber with red light, preventing the bees from seeing the blue flower, and introduced the ball. To complete the task, the bees needed to recall the location of the flower and position the ball beneath it – and 23 out of 30 bees were successful.
“We are not claiming that bees think like humans,” said Loukola. “But our findings show that miniature brains can generate flexible solutions to novel problems in ways we are only beginning to understand.”
Prof Lars Chittka, a behavioural ecologist at Queen Mary University of London, and author of The Mind of a Bee, who was not involved in the latest research, said: “We’ve seen bees do all kinds of remarkable things in our lab: counting, impressive object manipulation – but they surprise me every time. This is the clearest demonstration yet of some kind of comprehension of what’s at stake.”
“There’s a general perception that intelligent behaviour requires big brains because we are big-brained and relatively intelligent among animals,” Chittka added. “Bees are a model of how much intelligence you can squeeze into a small nervous system … It’s a good reminder of there being a motivation to pay some respect to these other beings.”
The findings are published in the journal Science.
