A team of Finnish scientists has shown that bumble bees can work out how to solve a problem they have never seen before, improvising a way to reach a reward with no training to guide them. The finding, published this month in the journal Science, adds to a run of recent results that question the idea that flexible, on-the-spot problem-solving belongs only to big-brained animals.
Working with the common buff-tailed bumble bee (Bombus terrestris), researchers from the Universities of Oulu, Helsinki and Turku set the insects a puzzle modelled on a famous experiment in animal cognition. The bees figured it out on their own.
An insect take on the box-and-banana problem
The setup borrows from a scenario familiar to anyone who has read about primate intelligence: the “box-and-banana” problem, in which an animal has to realise that an object lying around can be moved and stood upon to reach food that is otherwise out of reach.
“This is essentially an insect version of the classic ‘box-and-banana’ problem,” said senior author Olli Loukola. “The animal must realise that an object can be repositioned and then used as a tool to reach an otherwise inaccessible goal.”
The researchers first taught the bees that a blue artificial flower held a sugary reward. Then they moved the flower to the ceiling of the test arena, out of reach. The only route to the prize was to push a ball into position underneath the flower and climb on top of it, a sequence of actions the bees had never been shown or rewarded for doing.
Never trained to do it
What sets the result apart from earlier studies of bee learning is that the animals were never coached through the steps. In previous experiments showing ball-rolling in bees, the insects were trained, often by watching a demonstrator. Here, they were left to invent the solution themselves.
“What makes this behaviour especially remarkable is that the bees had never been trained to roll the ball,” said lead author Akshaye Bhambore. “This was a completely new challenge.”
Co-author Ece Nur Akmeşe described the change the team saw as the bees cracked the puzzle. “One moment the animal is exploring seemingly without direction, and the next it performs a highly efficient sequence,” she said. The bees shifted from aimless searching to a deliberate, goal-directed routine.
Ruling out luck
A series of control experiments was designed to rule out the duller explanations. The team checked for accidental success, for simple play behaviour, for trial-and-error learning, and for the possibility that the bees were just being visually drawn toward the flower as they moved around.
In the toughest version of the task, the flower was hidden from view while the bees moved the ball. Even then, the insects pushed it into the right spot. That suggests they were not simply following a visual beacon but acting on some internal sense of where the ball needed to go.
Big questions about small brains
A bumble bee brain holds fewer than a million neurons, against the tens of billions in a human brain. That such a small brain can come up with genuinely new solutions cuts against a neat story in which spontaneous problem-solving is reserved for large-brained vertebrates like apes and crows.
The authors argue the work shows that miniature brains can generate flexible solutions to novel problems, something researchers are only starting to map. It is one more piece of evidence that the cognitive gap between insects and vertebrates is smaller, and weirder, than biologists long assumed.
Source: Bhambore, Akmeşe, Häkkinen, Jussila, Kantola & Loukola, “Spontaneous problem-solving in bumble bees,” Science, vol. 392 (2026), pp. 1046–1049.
