Social insects like bees exhibit an impressive range of behaviors, from working together to build structurally complex nests (complete with built-in climate control) to a practical division of labor within their communities. Biologists used to view these behaviors as pre-programmed responses that evolved over generations in response to external factors. But two research papers last week reported findings suggesting social learning may also play a role.
The first, published in the journal PLoS Biology, showed that bumblebees can learn to solve simple puzzles by watching more experienced peers. the second, published in the journal Science, report evidence of similar social learning in how honey bees learn to perform their trademark “waggle dance” to tell other bees in their colony where to find food or other resources. Taken together, both studies add to a growing body of evidence for some kind of “culture” among social insects such as bees.
Culture can be broadly defined as behaviors that are acquired through social learning and maintained in a population over time, essentially serving as a ‘second form of inheritance’, but most studies have been done on species with relatively large brains: primates, cetaceans passer-by birds,” said co-author Alice Bridgesa postgraduate student at and working at Queen Mary University of London lab From the co-author Lars Schitka. “I wanted to study bumblebees in particular because they are ideal models for social learning experiences. They have been shown previously to be able to learn really complex and unnatural behaviors like string pulling both individually and socially.”
Ever since Charles Darwin noted in 1884 that bumblebees engage in “nectar theft”—biting the forager at the base of a flower to collect nectar but not pollinating a plant—scientists have recognized an amazing capacity for social learning in organisms of all species. Evolutionary theory is called Baldwin effect He says that certain beneficial behavioral traits learned in the life of one creature are passed on to its offspring through natural selection. So bridges et al. decided to explore the possibility that social learning contributes to unique behavioral innovations in bumblebees (Bombus terrestris), rather than being purely innate.
As previously reported, the group Chittka a Study 2017 It showed that bees could be trained to roll small wooden balls in order to get a reward. But the group also noted cases where bees chose to roll balls even when there was no clear reward or benefit. The spheres were placed in a tunnel connecting the cell to the experimental arena where the food was. Many bees walked over the balls or stopped to roll them back and forth from the food. The group wondered if this might be real play behavior.
Chittka Lab posted a file Study follow-up Last year she reported her observations of real play behavior in bees, which were filmed rolling small, colorful wooden balls. (While many animals have been known to engage in play, it is usually the large-brained mammals and birds.) For Chittka, this was “a strong indication that insect minds are much more complex than we might imagine.”
The idea to use two-choice puzzle box experiments to explore social learning came from previous research chimpanzee (2005) and Big tits (2015). For bees, Chittka’s lab designed puzzle boxes that can be opened by rotating a transparent lid, either by pressing clockwise on a red tab or counterclockwise on a blue tab. This would allow the bees to collect a tasty 50 percent sucrose solution.
A demonstration bee was trained to perform a solution behavior and then added to a group of untrained bees. All bees were allowed to forage freely among the puzzle boxes, and their behavior was monitored to see if the pretend bees repeatedly “solving” the puzzle box resulted in this behavior spreading to the rest of the group. There were also control groups with no pretender bees.
“We wanted to see if bumblebees could learn a new abnormal behavior through social learning under open propagation conditions,” Bridges said. “In particular, we were interested to see if they could learn variations of this behavior that were specific to trained demonstrators — just like these big-brained species.”
That’s exactly what happened. Foraging bees in colonies that had demonstration bees opened more puzzle boxes than control bees, and they used the “taught” solution 98 percent of the time, indicating that they had learned the behavior socially. In follow-up experiments with multiple pretender bees, each taught a different puzzle solution, the untrained bees initially learned both methods, but over time, preferences for one or the other were randomly developed, such as a fad or popular trend. Once there is a preferred solution, the bees usually stick to it.
As for the two control colonies, only one bee learned to open the puzzle boxes — an “automatic learner,” if you will — though it was less efficient at doing so and opened far fewer bees in colonies with a pretender. The second round of experiments that lasted longer produced fewer spontaneous learners, and less efficient ones as well. However, an automatic learning bee had great success, with 216 box openings recorded over the course of the experiment; Its closest competitor in the control groups opened only 22 funds over the same time period. By contrast, the trained display bees were expert foragers, routinely opening more than 100 puzzle boxes each day.
The findings are consistent with previous studies involving chimpanzees and great tits, where the authors argued that such social learning demonstrated those species’ ability to culture. “Bumblebees are not known to exhibit culture-like phenomena in the wild,” Bridges said. “However, our bees seem to have been able to. I was also surprised at how flexible and innovative bumblebee behavior was. The fact that some bees learned to open boxes themselves was really cool and definitely suggests that bees may come up with other new behaviors in the wild – as long as the opportunity arises. and need.
Further studies of the nectar-stealing behavior of bumblebees could shed more light on the underlying mechanisms. But can this socially learned behavior be passed on to later generations? This type of bumblebee is difficult to test. “Bumblebees in our experiments form colonies that last for one biological generation before molting, but honey bees, stingless bees, and some tropical bees form colonies that last for many years,” she says. Bridges said. “If a long-standing, naturally occurring culture was found in invertebrates, it would probably be here.”
This is where the second study took place wiggle dances in honey bees. “We are beginning to understand that, like us, animals can transmit information important to their survival through communities and families,” James Nie said of the University of California San Diego, who is a co-author of this study. “Our new research shows that we can now extend such social learning to insects. We know that bees are quite intelligent and have the ability to do amazing things.”
Honeybees use their waggle dance to tell other bees where to find important resources such as food, water, tree resins, and nest sites. The “dance” involves rocking their bellies in the shape of a figure-eight, and is done at a remarkably fast pace: a bee can move an entire body in less than one second. Longer oscillations indicate longer distances, while the angle of vibration direction indicates direction. The quality of the resource in question is encoded in how many times the vibration is triggered and in how quickly each dancing bee returns to repeat successive cycles.
per nih et al. Workers begin to follow the foraging of dancing bees at about eight days of age and start dancing themselves at 12 days, usually dancing the same “routine” as the older bees who kept dancing. intention et al. It figured that those first waggle dances would therefore have more communication errors if the bees were reared without being able to follow the older dancers. So they bred colonies of honey bees with young bees of the same age and watched for the emergence of wiggling dance behaviour, along with control colonies mixed with older, experienced bee dancers.
The results support their hypothesis. The first wagging dances of bees who could not cope with older experienced forager bees were riddled with errors regarding the direction and distance between valuable resources. While they were able to improve through training or watching other bees, they were never able to properly encode distance. Bees in mixed control colonies gained valuable social cues by following experienced dancers, so their first dances were much more subtle. And that social knowledge stayed with them throughout their lives.
Basically, untrained bees have evolved their own unique distance dialect. “Scientists believe that bees’ accents are shaped by their local environments,” Nih said. “If that is the case, it makes sense for the colony to pass on a dialect well adapted to this environment.” He and his colleagues believe their findings indicate that social learning shapes honeybee signals, as it does in many vertebrate species.
“It is at least plausible that there may be subtly different local ‘cultures’ that are socially acquired for dance language and depend on the visual characteristics of landscapes or the spatial distribution of food sources,” Chitka and Natasha Rossi (from the University of Sussex in Brighton) wrote in an accompanying commentary. They were martyred a Study 2008 It turns out that one species of honeybee learned to read through another species’ space code, and so did the shietka et alA study on the joyful ball rolling in bees. “It is therefore plausible that some of their most advanced behavioral innovations (including elements of dance language) may have emerged at least in part through individual innovation and subsequent social learning, becoming instinctive later in evolutionary time.”
DOI: Science, 2023. 10.1126/sciences.ade1702 (about DOIs).
DOI: PLoS Biology, 2023. 10.1371/journal.pbio.3002019 (about DOIs).
“Beer aficionado. Gamer. Alcohol fanatic. Evil food trailblazer. Avid bacon maven.”