Unlocking the Secrets of the Honeybee Dance Language
The Greek historian Herodotus reported more than 2,000 years ago about an erroneous forbidden experiment in which two children were prevented from hearing human speech so that the king could discover the true, unlearned language of the people.
Scientists now know that human language requires social learning and interaction with other people, which is common to many animal languages. But why should humans and other animals learn language, and not be born with this knowledge, like many other animal species?
This question interests me and my colleagues and formed the basis of our recent article published in the journal Science. As a biologist, I have spent decades studying honey bee communication and how it might have evolved.
There are two common answers to the question of why a language should be learned or innate. First, complex languages can often respond to local conditions as they are learned. The second answer is that complex communication is often difficult, even if people are born with some knowledge of the right signals. Given that honey bees’ ways of communicating are quite complex, we decided to study how they learn these behaviors in order to answer this language question.
What is a wagging dance?
Surprisingly, honey bees have one of the most complex examples of non-human communication. They can tell each other where to find resources such as food, water, or nesting sites through a physical “waggle dance”. This dance informs the bees about the direction, distance, and quality of the resource.
Essentially, the dancer points the recruits in the right direction and tells them how far they need to go by repeatedly circling in a figure-of-eight pattern centered around a wagging run in which the bee wags its abdomen as it moves forward. The dancers are harassed by potential recruits, bees who keep a close eye on the dancer to find out where to go to find the reported resource.
Longer wobbling runs communicate longer distances, and wobbling angle reports direction. For higher quality resources, such as sweeter nectar, the dancers repeat the waggle run more times and come back faster after each waggle run.
This dance is hard to put on. The dancer not only runs covering approximately one body length per second, but also tries to maintain the correct angle and duration of the waggle. Also usually in complete darkness, among a crowd of jostling bees and on uneven ground.
Thus, bees can make three different types of errors: pointing in the wrong direction, signaling the wrong distance, or making more mistakes when performing the figure-of-eight dance—what researchers call confusion errors. The first two mistakes make it difficult for recruits to find the reported location. The clutter bug can make it difficult for recruits to follow the dancer.
Scientists knew that all bees of the species Apis mellifera only begin to forage and dance as they grow older, and that they also follow experienced dancers before they first attempt to dance. Can they learn from experienced teachers?
“Forbidden” bee experiment
So my colleagues and I created isolated experimental colonies of bees that couldn’t watch other waggle dances before they started dancing themselves. As in the ancient experiment described by Herodotus, these bees could not observe the language of the dance because they were all the same age and had no older, more experienced bees to follow. In contrast, our control colonies had bees of all ages, so the younger bees could follow the older, more experienced dancers.
We recorded the first dances of bees living in colonies with both age profiles of populations. The bees that could not follow the dances of the experienced bees produced dances with significantly more errors in direction, distance, and confusion than those of the novice control bees.
We later tested the same bees when they were already experienced foragers. The bees that had no teachers now made significantly fewer directional errors and confusion, perhaps because they had more practice or learned by ending up following other dancers. The dances of the older control bees from families with teachers were as good as their first dances.
This discovery tells us that bees are born with some knowledge of how to dance, but they can learn to dance even better by following experienced bees. This is the first known example of such complex social communication learning in insects, which is a form of animal culture.
Dance dialects about distance
The mystery was the bees, who previously lacked dance teachers. They could never correct their distance errors. They continued to miss, reporting greater distances than usual. So why is it interesting for scientists? The answer may lie in how telecommuting can adapt to local conditions.
There can be significant differences in the distribution of food in different environments. As a result, different species of honey bees have evolved different “dance dialects”, described as a relationship between the distance to a food source and the corresponding duration of the waggle dance.
Interestingly, these dialects differ even within the same honey bee species. The researchers suspect this variation exists because colonies, even those of the same species, can live in very different environments.
If learning a language is a way of coping with different conditions, then perhaps each colony should have a distance dialect adapted to its place and passed on from experienced bees to novices. If so, then our individual bees, deprived of teachers, may never correct their distance errors because they themselves have learned a different dialect of distance.
This dialect is usually taught by experienced bees, but it could potentially change within a generation if their environmental conditions change or if the colony swarms in a new location.
In addition, each colony has a “dance floor” or space where the bees dance, with challenging terrain over which the dancers can learn to better navigate with time or follow in the footsteps of older dancers.
These ideas are yet to be tested, but they lay the foundation for future experiments that will study cultural transmission between older and younger bees. We believe that this study and future research will expand our understanding of collective knowledge and language learning in animal communities.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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