Paper wasps capable of behavior that resembles logical reasoning – ScienceDaily

For millennia, transitive inference was considered a feature of human deductive powers, a form of logical reasoning used to make inferences: if A is greater than B and B is greater than C, then A is greater than C.

But in recent decades, vertebrate animals, including monkeys, birds, and fish, have demonstrated their ability to use transitive inference.

The only published study that evaluated IT in invertebrates revealed that honeybees were not up to the task. One of the possible explanations for this result is that the small nervous system of honeybees imposes cognitive constraints preventing these insects from carrying out a transitive inference.

The paper wasps have a nervous system about the same size – about a million neurons – as bees, but they exhibit complex social behavior typical of bee colonies. Elizabeth Tibbetts, an evolutionary biologist from the University of Michigan, asked if the social skills of paper wasps could enable them to succeed where bees had failed.

To find out, Tibbetts and his colleagues checked whether two common species of paper wasps, Polistes dominula and Metric Polistescould solve a problem of transitive inference. The results of the team must be published online May 8 in the newspaper. Biology Letters.

"This study adds to a growing body of evidence that miniature insect nervous systems do not limit sophisticated behaviors," said Tibbetts, a professor in the Department of Ecology and Evolutionary Biology.

"We are not saying that wasps used logical deduction to solve this problem, but they seem to use known relationships to make inferences about unknown relationships," Tibbetts said. "Our findings suggest that complex behavioral capacity can be shaped by the social environment in which behaviors are beneficial, rather than being strictly limited by brain size."

To test TI, Tibbetts and his colleagues first collected paper queens in several locations around Ann Arbor, Michigan.

In the laboratory, wasps were trained to distinguish between pairs of colors called pairs of premises. One color in each pair was associated with a slight electric shock, and the other was not.

"I was really surprised at the speed and accuracy with which the wasps learned the pairs of premises," said Tibbetts, who has been studying the behavior of paper wasps for 20 years.

Later, the wasps were presented with pairs of colors that were unknown to them, and they had to choose between the colors. The wasps were able to organize the information into an implicit hierarchy and used transitive inference to choose between new pairs, Tibbetts said.

"I thought wasps could become confused, just like bees," she said. "But they had no trouble understanding that a particular color was safe in some situations and not safe in others."

So, why are wasps and honeybees – which both have a smaller brain than a grain of rice – have such different performances during transitive inference tests? One possibility is that different types of cognitive abilities are favored in bees and wasps because they display different social behaviors.

A honeybee colony has a single queen and several workers of equal rank. On the other hand, paper wasp colonies have several breeding females called founders. The founders compete with their rivals and form linear dominance hierarchies.

The rank of a wasp in the hierarchy determines the shares of breeding, labor and food. Transitive inference could allow wasps to quickly infer new social relationships.

The same hypotheses could allow the paper wasp women to spontaneously organize information during transitive inference tests, according to the researchers' hypothesis.

For millennia, transitive inference was considered a feature of human cognition and was supposed to be based on logical deduction. More recently, some researchers have wondered whether TI requires higher reasoning or can be solved with simpler rules.

The study by Tibbetts and his colleagues shows that paper wasps can construct and manipulate an implicit hierarchy. But he makes no claim about the precise mechanisms that underpin this ability.

In previous studies, Tibbetts and his colleagues had shown that paper wasps recognized individuals of their species by variations in facial markings and behaved more aggressively with wasps with unknown faces.

Researchers have also shown that paper wasps have a surprisingly long memory and base their behavior on what they remembered from past social interactions with other wasps.

The other authors of the new Biology Letters paper – Jorge Agudelo, Sohini Pandit and Jessica Riojas – are undergraduate students.

The work was supported by the National Science Foundation and the Doris Duke Conservation Fellowship Program of the University of Michigan, funded by the Doris Duke Charitable Foundation. All experiments were in accordance with US laws and international ethical standards.