Most people associate the term “culture” with going to the theater and concerts, eating together in a good restaurant or reading the feuilleton section of a newspaper. But taking the term a bit broader, culture means that members of a community cultivate a habit that distinguishes them from their peers and that they pass on to one another.
In this sense, culture is not typically human, but is also common in the animal kingdom. However, culture in nature has so far mainly been found in animals that are considered to be particularly intelligent anyway: a certain group of chimpanzees in Zambia, for example, cultivates the culture of sticking a blade of grass in their ear – nobody knows why, maybe the apes just think it’s chic . Orca families communicate in different “dialects” that distinguish them from their peers. And cockatoos living in Australia’s capital, Sydney, have an ingenious way of opening garbage cans to get at what they see as delicious contents.
But insects with their mini brains? Researchers at Britain’s Queen Mary University of London have now discovered that bumblebees at least have the cognitive requirements to develop a culture: The team around Alice Bridges describes in the specialist journal Plos Biologythat the insects copy certain behaviors from a trendsetter bumblebee and then pass it on to each other until eventually all the animals in the colony adopt the new behavior.
In principle, there are two ways of researching whether a certain animal species is capable of developing culture. The first is to observe and compare the behavior of different populations of the same species in the wild. This is complex and takes a long time – often several years.
The second option is to train animals in captivity to behave in a certain way, then place them in contact with untrained animals and observe whether and how the behavior spreads. Behavioral biologists refer to this type of experiment as the “open diffusion paradigm”.
The researchers led by Alice Bridges chose this approach. The experiments with the bumblebees took place in a specially developed “flight arena”. There they confronted their test subjects with a small box containing a sugar solution on a yellow base as a reward, which the bumblebees probably mistook for a somewhat unusual flower with particularly tasty nectar. The box was closed with a transparent lid, which the bumblebees could open in two different ways: When the animals pulled a red lever, the lid turned clockwise and opened. On the other hand, if they pressed a blue lever, the lid turned in the other direction, but also released the reward.
Bumblebees do not survive the winter, they can at most develop a kind of short-term culture
In a first experiment, the researchers taught a single bumblebee, which had shown particular interest in the strange box in a previous experiment, to use the red lever to get the reward in several steps. Then they put the trained bumblebee in a flight arena with untrained fellows who had no idea what to do with the box. But that changed very quickly. After six days, during which the researchers filmed the behavior of the insects, almost all of the bumblebees were able to open the box. And they did it in exactly the same way the trained bumblebee had been taught: by pulling the red lever. “A few bumblebees discovered for themselves that the box could also be opened by pressing the blue lever,” the researchers write in their study. But these animals still preferred the variant with the red lever.
The same thing happened when the researchers taught the trendsetter bumblebee to press the blue lever: After six days, everyone else had also learned to press the blue lever to open the box.
According to the authors of the study, these results indicate that the bumblebees copied the opening trick through social learning from the trained model and did not come up with the solution themselves. Even more important than this observation is the realization that the newly learned behavior has spread among the bumblebees. “To our knowledge, this is the first time this has been shown in an invertebrate,” the researchers write Plos Biology.
At least theoretically, bumblebees have the prerequisites to establish animal cultures like chimpanzees, orcas and cockatoos. However, it is still unclear whether they actually do this: This is supported by the fact that there are definitely differences in the architecture and also in the social organization of the nest in bumblebees within one and the same species, which could be an expression of a culture. On the other hand, unlike honey bees, bumblebee colonies die in winter. So they cannot pass on newly learned behaviors to the next generation and at best develop a kind of short-term culture.