Complex learned social behavior discovered in ‘bee dance’

The transmission of shared knowledge from one generation to the next is a hallmark of civilization and allows animals to adapt quickly to a changing environment.

Although widely evident in species ranging from human infants to naked mole rats or fledgling songbirds, early social learning has now been documented in insects.

Journal publication Science, a researcher at the University of California, San Diego, and his colleagues have uncovered evidence that social learning is fundamental to bees. Professor James Nieh of the School of Biological Sciences and his colleagues discovered that the ‘waggle dance’, which signals the location of critical resources in nestlings through a complex series of movements, improves with learning and can be culturally transmitted. The study demonstrates the importance of early social cue learning in one of the most complex known examples of non-human spatial reference communication.

“We are beginning to understand that, like us, animals can transmit information important to their survival through communities and families. Our new research shows that we can now extend such social learning to include insects,” said Nieh, a professor at Department of Ecology, Behavior and Evolution.

A social insect with a highly organized community structure, bees help ensure the survival of their colonies by communicating the location of food sources to each other through a waggle dance in which the bees circle in figure eights while shaking their bodies during of the central part of the dance.

Performed at breakneck speed (each bee moves a body length in less than a second), the movements within the dance translate visual information from the environment around the hive and the position of the sun into distance, direction and even resource quality to partners. Accurately transmitting this information is a remarkable feat because bees must move quickly over an often uneven hive surface.

Nieh and fellow researchers Shihao Dong, Tao Lin and Ken Tan of the Chinese Academy of Sciences (CAS) set up experiments testing the details involved in waggle dance communication. They set up colonies to study the process of information transmission between skilled forager bees and their younger, less experienced mates.

The experimenters created colonies in which bees were never able to observe or follow waggle dancers before they danced for the first time. These colonies consisted of young bees that were all the same age. Bees begin to dance when they reach the right age and always follow experienced dancers before attempting to dance for the first time. In these experimental colonies, the bees were never able to learn from more experienced dancers.

“Bees that did not have the opportunity to follow any dancer before dancing for the first time produced much more erratic dances with larger wave angle deviation errors and miscoding of distance,” the researchers noted in the paper.

In contrast, bees that shadowed other honeybees in control colonies suffered no such problems. Like humans, for whom early exposure to language development is essential, bees acquired social cues that were encoded and stayed with them for life (about 38 days).

Those who did not learn the correct waggle dance early on were able to improve by subsequently watching other dancers and practicing, but were never able to code the distance correctly. This distance coding creates the distinct “dialects” of different bee species. In other words, bees that could never observe other dancers during the critical initial stage of their learning developed a new dialect that they maintained for the rest of their lives.

“Scientists believe that bee dialects are shaped by their local environment. If so, it makes sense that a colony would transmit a dialect that is well adapted to that environment,” said Nieh. Therefore, the results provided evidence that social learning shapes bee signaling as it does early communication in many vertebrate species that also benefit from learning.

With their new results, Nieh and his colleagues would now like to understand the role of the environment in shaping bee language. In the future, they would like to know whether the older, more experienced bees in the colony who know the distribution of food sources in their environment could pass on an optimized dialect to the next generation.

They also worry that external threats could disrupt this early language learning. Multiple studies, including those by Nieh and colleagues, have demonstrated the harm that commonly used pesticides can cause bees.

“We know that bees are quite intelligent and have the ability to do remarkable things,” Nieh said. “Multiple papers and studies have shown that pesticides can impair the cognition and learning of bees, and therefore pesticides can impair their ability to learn how to communicate and potentially reshape how that communication is transmitted to the next generation of bees in a colony.”