Bumblebee Intelligence Challenges Human Exceptionalism

The unassuming bumblebee demonstrates that brain size is not the whole story.

Despite having a tiny brain roughly the size of a seed, this small insect has displayed a form of collective intelligence in experiments that scientists had believed was entirely exclusive to humans.

In laboratory training, bumblebees of the species Bombus terrestris learned to open a puzzle box requiring two actions. They could then pass the solution on to another bee that had never encountered the box.

That inexperienced bee would not have cracked the puzzle unaided. Beforehand, researchers needed to teach the ‘demonstrator’ bees the unintuitive method, showing them each action and providing a reward after the first stage to sustain their motivation.

“This finding challenges a common opinion in the field: that the capacity to socially learn behaviors that cannot be innovated through individual trial and error is unique to humans,” write the team of researchers based in the United Kingdom and United States.

Humans have repeatedly ‘moved the goalposts’ when deciding which traits make our species distinct from every other animal.

At one time, culture was considered uniquely human. Yet ‘viral’ sparrow songs, whales’ changing dialects and traditions, orcas’ local hunting methods, and learned tool-use techniques among apes, crows, and dolphins all indicate that animal societies also possess socially transmitted behaviours.

Several of these cultural behaviours appear to be refined and enhanced over time. Homing pigeons, for example, learn from one another and alter the flight routes within their culture from year to year.

Bumblebee intelligence and social learning

One influential way of redefining human intelligence is to argue that humans differ from other animals because we can acquire knowledge from one another that we could not independently invent.

Consider the device on which you are reading this article. No individual could create every component and mechanism from nothing, alone and within a single lifetime. Reaching its present sophistication has required decades of work and refinement. Reading itself is likewise an ability gradually developed by generations of humans.

Clearly, no animal can assemble an iPhone or read an article about animal intelligence. Nonetheless, at a fundamental level, bumblebees, alongside chimpanzees, are “cast[ing] serious doubt on this supposed human exceptionalism,” Alex Thornton, an ecologist at the University of Exeter, writes in a Nature review of the bumblebee study.

Chimpanzees have substantial brains and complex cultural lives. However, Thornton says the bumblebee finding is “all the more remarkable because it focuses not on humanity's primate cousins, but on… an animal with a brain that is barely 0.0005 percent of the size of a chimpanzee's.”

Bumblebees were underestimated for decades, largely due to their small size, but are now beginning to receive proper recognition.

Recent laboratory studies have shown that these bees can learn from each other, use tools, count to zero, and carry out basic mathematical equations.

Their hive mind’s collective intelligence should not be underestimated either.

The two-step bumblebee puzzle box

To investigate this capacity, behavioural scientist Alice Bridges of Queen Mary University of London and her colleagues kept bumblebee colonies with a two-stage puzzle for either 36 or 72 hours, across 12 or 24 successive days, without human assistance.

Even after this period, the insects did not discover how to reach the sugary prize. Bumblebees forage for approximately 8 days on average during their lives, meaning they effectively had as much as one-third of their lifetime foraging time to tackle the puzzle.

The puzzle contains a drop of sugar beneath a plastic lid within a yellow circle. Bees can reach it by pressing the red tab, but only after first moving the blue tab aside.

A person had to carefully demonstrate the process to the bees, and even that could only be achieved with an additional reward. Once a single bee had solved the puzzle, however, it was able to show others how to shift the two tabs and obtain the sugary reward.

A comparable experiment involving chimpanzees was recently published in Nature Human Behaviour. The vertebrate and invertebrate studies both revealed the transmission of ideas that were exceptionally difficult to acquire alone.

Naturally, researchers did not witness this behaviour in the wild: both the bees and chimpanzees first had to be taught it. Still, the results allow for the possibility that a rare, once-in-a-lifetime innovator in a chimpanzee or bee society – an Einstein among bees – could have ideas that persist in animal culture and are used for generations.

For example, bees’ renowned honey waggle dance communicates the distance, direction, and quality of food sources. It was once regarded as wholly instinctive, but now seems to be shaped to some extent by social influences.

What the findings mean for animal culture

In 2017, researchers trained bumblebees to roll a ball into a goal in return for a reward. To score, the insects needed to learn from one another and correct earlier errors. They did so.

The latest experiment, Thornton writes, “suggests that the ability to learn from others what cannot be learnt alone should now join tool use, episodic memory (the ability to recall specific past events) and intentional communication in the scrapheap” of explanations for human cognition and culture.

The study was published in Nature.