A new study led by the University of Michigan (U-M) has found that, regardless of their tiny brains, paper wasps (Polistes fuscatus) are capable of learning abstract concepts. Even more surprisingly, these wasps were also able to transfer what they learned through visual training into a different sensory modality: the olfactory sense.
In a series of previous studies, U-M evolutionary biologist Elizabeth Tibbetts and her colleagues have shown that paper wasps have an amazing capacity to learn, remember, and make social distinctions about others. For instance, they can recognize individuals of their species by variations in their facial markings, and they behave more aggressively towards wasps with different markings. Moreover, these wasps seem to have surprisingly long memories, basing their actions on what they remember of previous social interactions, and are able of transitive inference – a behavior resembling logical reasoning.
In the current study, the experts used laboratory tasks to test whether the wasps can learn and apply one of the most basic abstract concepts – the idea of sameness and difference. The wasps were trained to distinguish between pairs of visual or olfactory stimuli – two colored pieces of paper, two pictures of wasp faces, or two chemical odors – which were either identical or different. While one pair of stimuli was associated with a mild but unpleasant electrical shock, the other one was not.
Afterwards, the insects were exposed to new pairs of stimuli and tested on their capacity to avoid electric shocks by selecting the “correct” pair. Strikingly, trained wasps made the correct choice over 80 percent of the time. “Our findings show the wasps learned the general concept of sameness and difference and applied it to new samples and new types of stimuli,” said Professor Tibbetts. “Abstract concepts are thought to be associated with high levels of cognitive sophistication, so there has been much interest in which species can form and use them. This is the first time anyone has shown that wasps can form abstract concepts.”
“Remarkably, wasps applied the concept of sameness and difference across sensory modalities, as they transferred concepts learned in the visual domain to the odor domain,” added study first author Chloe Weise, a former master’s student at U-M. “Therefore, our results illustrate that Polistes are able to master abstract interrelationships between stimuli.”
Although several species of vertebrates such as primates, pigeons, crows, parrots, dolphins, and ducklings are able to form abstract concepts, paper wasps are only the second invertebrate species (after honeybees) that were capable to do this. Further research is needed to clarify the mechanisms by which they perform this amazing feat, and compare them to those employed by other species.
The study is published in the journal Proceedings of the Royal Society B Biological Sciences.