A recent scientific article on bumblebees, a genus of insects from the same family as bees, has provided some relevant information in support of a hypothesis that has long been discussed in the field of ethology, the part of biology that studies animal behavior. The hypothesis is that the typically human capacity to learn from others more than it is possible to learn from oneself in the course of a lifetime – a necessary condition for the formation of what we define as “culture” – is a capacity shared with other animal species.
Published in March in the magazine Nature by a group of researchers from Queen Mary University of London and the University of Sheffield, the article describes the results of an experiment in which bumblebees were asked to solve a complex problem on a kind of turntable inside a box . To obtain a reward (a sugar solution) that they perceived but could not directly reach, the bumblebees had to perform two actions in sequence: unlock a turntable by pushing a latch and then rotate it counterclockwise.
The bumblebees, which are considered prodigious insects in social learning, failed to solve the problem during the experiment, even after a prolonged exposure time of 24 days. Some succeeded only after training: in practice the experimenters induced them to learn the intermediate step by placing an initial reward on the latch that had to be pushed to unlock the platform. At that point the bumblebees also managed to overcome the second step and get to the sugar solution.
The surprising result considered most significant by the researchers is that a group of untrained bumblebees, who like all the others had not initially been able to solve the problem, later managed to understand how to act without needing the first reward. He limited himself to learning from the behavior of a “demonstrator” bumblebee, that is, one of those trained to pass the first step.
The ability of non-human animals to perform new actions by learning from the behavior of their peers has been known and studied for decades in species such as chimpanzees, macaques, crows and humpback whales. The result described in the study published on Nature however, it is considered the first evidence of the presence of this social capacity among invertebrates, applied to the solution of particularly complex problems: problems that are too difficult for a single individual to solve by proceeding by trial and error.
Some comments on this experiment and other similar ones have interpreted the results as further evidence of the possibility that culture, understood as the ability of a species to learn and spread complex behaviors in a population, is not a uniquely human fact. The example of bumblebees is significant because it suggests that even the behaviors of insects whose sophisticated social structures have long been known, such as bees, could be at least partly learned behaviors and not innate, which was the prevailing hypothesis until now.
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Although it is used in many different ways in common language, the word “culture” in ethology and other related disciplines has a fairly precise meaning. Indicates the set of behavioral traditions of a population, that is, behaviors passed down through social learning and which persist in a group or society over time. Researchers have observed numerous behaviors across the animal kingdom that meet this definition of cumulative culture, characterized by sequential innovations that build on previous ones.
Almost every part of human life is based on knowledge and technologies of this type, which are too complex to be managed by an individual independently and without a cultural tradition. Otherwise it would not have been possible to travel in space, for example, or even operate a toilet.
An article published in the magazine in March Nature Human Behavior presented the results of an experiment similar to the one with bumblebees, but conducted with chimpanzees by a group of researchers from the University of Utrecht, in the Netherlands, and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. In the Chimfunshi Wildlife Orphanage, a wildlife refuge in Zambia, researchers left a box of peanuts that functioned as a kind of vending machine available to a community of 66 chimpanzees, divided into two groups.
The chimpanzees could see and smell the peanuts, but to reach them they had to operate the dispenser by picking up one of the wooden pellets left nearby by researchers. The box had a spring-loaded drawer that you had to open and keep open, because inside there was a recess into which you could slide the ball to receive a handful of peanuts. After three months in which no chimpanzee could operate the dispenser, the researchers selected an older female from each of the two groups for training.
“You cannot choose an animal at random,” said Edwin van Leeuwen, one of the authors of the study, explaining that for the success of training it is important to select bold and medium-high-ranking individuals within the group. Once the training of the two females was finished, the distributor was repositioned and left again available to the two groups. After two months spent in the presence of the trained individuals, 14 chimpanzees managed to operate the dispenser by repeatedly observing the behavior of another individual who had understood how to make it work.
Both the chimpanzee and bumblebee studies are considered important experimental evidence of social learning in animals, for which there has long been ample anecdotal evidence. The ability to learn by observing and imitating the behavior of other individuals is in fact considered one of the factors that contribute to determining intraspecific behavioral differences between different groups.
From chimpanzees, for example, the practice of using sticks or blades of grass to capture termites is well known, observed and studied since the early 1960s by the English ethologist Jane Goodall. But at the end of the nineties the zoologist and psychologist Andrew Whiten discovered together with his research group at the University of St Andrews, in Scotland, and with Goodall herself that chimpanzees use termite capture techniques differently depending on the group a to which they belong. Those in some parts of Africa eat insects directly from the stick, while others use their free hand to pick them up before eating.
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In recent years, the amount of evidence for the existence of different social behaviors, eating habits and even songs and calls between groups of the same species has also increased. The differences are due to environmental factors, but are also made possible by the social tendency to welcome and spread elements of innovation introduced by individuals within groups. Evidence of similar cultural evolution has been observed among killer whales, sperm whales and other cetaceans, but also among several bird species.
Cultural differences within the same species can also be reflected in more stable and evident aspects of social life, as some researchers from the biology department of the Katholieke Universiteit Leuven, in Belgium, and the entomology laboratory of the Embrapa institute have shown, in Brazil, in an article published in the magazine in March Current Biology. In a large apiary in Jaguariúna, Brazil, the research team observed 416 colonies of Scaptotrigona depilisa species of stingless bee found in South America, for two long periods in 2022 and 2023.
About 95 percent of the colonies had combs built in overlapping horizontal layers, https://twitter.com/JfersonPedrosa1/status/1636543564153847810 on multiple levels, the type of structure preferred by Scaptotrigona depilis. The remaining colonies instead had a spiral structure: in both cases the architectural style was maintained for many generations of bees. There were also no differences in construction speed, so no efficiency advantage in following one style over the other.
To exclude that the difference in style derived from genetic factors, the research group transplanted some individuals from colonies whose combs were built in multiple layers into colonies with spirally structured combs, and vice versa. Before doing so, he emptied the host structures so as not to leave “indigenous” adults in the colony, who could have influenced the behavior of the imported workers. Soon the imported bees adopted the local style, which was also inherited by the colony’s larvae as they matured into adults.
According to biologist Tom Wenseleers, head of the KU Leuven laboratory that conducted the research, bees may be changing their style to cope with the accumulation of microscopic construction errors made by their predecessors. This process, in which some individuals of social insects indirectly influence the behavior of others through the traces they leave in their environment, is called stigmergy. To confirm Wenseleers’ hypothesis, the group then introduced micro-variations in the structure of honeycombs with overlapping horizontal layers, and discovered that in that case the bees actually switched to the spiral construction.
The results of the study on bees in Jaguariúna suggest that the transmission of different honeycomb-building traditions across generations can occur even without the need for individuals to be directly taught by their peers. They therefore allow us to think about culture in broader terms, without understanding it rigidly as a set of behaviors transmitted from individual to individual until they become characteristic of a group.
The transmission of more complex animal behaviors – such as dam building by beavers or tree bedding by chimpanzees – could also occur in this same indirect way, Whiten told theEconomist. And it is possible that stigmergy processes are also at the basis of the transmission of some human traditions.
