Culture refers to behaviors that are socially learned and persist within a population over time. Increasing evidence suggests that animal culture can, like human culture, be cumulative. However, human cumulative culture involves behaviors so complex that they lie beyond the capacity of any individual to independently discover during their lifetime. New research shows that buff-tailed bumblebees (Bombus terrestris) can learn from trained conspecifics to open a novel two-step puzzle box to obtain food rewards, even though they fail to do so independently.
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Buff-tailed bumblebees (Bombus terrestris) socially learn behavior too complex to innovate alone. Image credit: Ralphs Fotos.
“This groundbreaking research opens new avenues for understanding animal intelligence and the evolution of social learning,” said study senior author Professor Lars Chittka, a researcher at Queen Mary University of London.
“It challenges longstanding assumptions and paves the way for further exploration of the cognitive wonders hidden within the insect world, even hinting at the exciting possibility of cumulative culture amongst seemingly simple creatures.”
Professor Chittka and his colleagues designed a two-step puzzle box requiring bumblebees to perform two distinct actions in sequence to access a sweet reward at the end.
Training bees to do this was no easy task, and bees had to be helped along by the addition of an extra reward along the way.
This temporary reward was eventually taken away, and bees subsequently had to open the whole box before getting their treat.
Surprisingly, while individual bees struggled to solve the puzzle when starting from scratch, those allowed to observe a trained demonstrator bee readily learned the entire sequence — even the first step — while only getting a reward at the end.
The study demonstrates that bumblebees possess a level of social learning previously thought to be exclusive to humans.
They can share and acquire behaviors that are beyond their individual cognitive capabilities: an ability thought to underpin the expansive, complex nature of human culture, and one previously thought to be exclusive to us.
“This is an extremely difficult task for bees,” said study first author Dr. Alice Bridges, a researcher at Queen Mary University of London and the University of Sheffield.
“They had to learn two steps to get the reward, with the first behavior in the sequence being unrewarded.”
“We initially needed to train demonstrator bees with a temporary reward included there, highlighting the complexity.”
“Yet, other bees learned the whole sequence from social observation of these trained bees, even without ever experiencing the first step’s reward.”
“But when we let other bees attempt to open the box without a trained bee to demonstrate the solution, they didn’t manage to open any at all.”
Beyond individual learning, this research opens exciting possibilities for understanding the emergence of cumulative culture in the animal kingdom.
Cumulative culture refers to the gradual accumulation of knowledge and skills over generations, allowing for increasingly complex behaviors to develop.
The bees’ ability to learn such a complex task from a demonstrator suggests a potential pathway for cultural transmission and innovation beyond their individual learning capabilities.
“This challenges the traditional view that only humans can socially learn complex behavior beyond individual learning,” Professor Chittka said.
“It raises the fascinating possibility that many of the most remarkable accomplishments of the social insects, like the nesting architectures of bees and wasps or the agricultural habits of aphid- and fungus-farming ants, may have initially spread by copying of clever innovators, before they eventually became part of the species-specific behavior repertoires.”
The research is described in a paper published March 6, 2024 in the journal Nature.
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A.D. Bridges et al. Bumblebees socially learn behaviour too complex to innovate alone. Nature, published online March 6, 2024; doi: 10.1038/s41586-024-07126-4
