A recent study from the University of Michigan provides the first evidence of a transitive inference, the ability to use known relationships to infer unknown relationships in a non-invertebrate animal: the low paper wasp.
For millennia, transitive inference was considered a characteristic of human deductive forces, a logical reasoning used for inferences: If A is greater than B and B is greater than C, A is greater than C. [1
The only published study investigating TI in invertebrates found that honey bees were not up to the task. One possible explanation for this finding is that the honeybee's small nervous system imposes cognitive constraints that prevent these insects from leading a transitive inference.
Paper wasps have a nervous system that is about the same size – about one million neurons – but they are showing a typical social behavior that is not seen in honey bee colonies. Elizabeth Tibbetts, the evolutionary biologist at the University of Michigan, wondered if the social abilities of paper wasps could make it possible for honey bees to fail.
To find out, Tibbetts and their colleagues have tested whether two common types of paper wasps, Polistes dominula and Polistes metricus, could solve a problem with transitive inferences. The results of the team will be published online on May 8 in the journal Biology Letters .
"This study increasingly provides more evidence that the insect's miniature nervous system does not restrict complex behavior," he told Tibbetts, a professor in the Department of Ecology and Evolutionary Biology.
"We do not say that wasps used logical deduction to solve this problem, but they seem to use familiar relationships to draw conclusions about unknown relationships," Tibbetts said. "Our findings suggest that the ability to handle complex behaviors may be determined by the social environment in which behavior is beneficial and not strictly limited by brain size."
To test TI, Tibbetts and her colleagues first collected Wasp queens from paper from several locations around Ann Arbor, Michigan.
Individual wasps were trained in the laboratory to distinguish color pairs, so-called premise pairs. One color in each pair was associated with a slight electric shock, the other not.
"I was really surprised how quickly wasps learned the premise pairs," said Tibbetts, who studied the behavior of paper wasps for 20 years.
Later, the wasps were presented with unknown color pairs and they had to choose between the colors. The wasps were able to organize information in an implicit hierarchy and used a transitive inference to choose between novel pairs, Tibbetts said.
"I thought wasps could be confused, just like bees," she said. "But they had no trouble finding out that a certain color was safe in some situations and not safe in other situations."
So why do wasps and honey bees, both of which have a smaller brain than a grain of rice, work so differently? on transitive inference tests? One possibility is that different types of cognitive ability are favored in bees and wasps because they show different social behaviors.
A honey bee colony has a single queen and several equal female workers. In contrast, paper wasp colonies have several reproductive women known as founders. The founders compete with their rivals and form linear dominance hierarchies.
The rank of a wasp in the hierarchy determines the proportion of reproduction, work and food. Transitive inference could allow wasps to quickly draw conclusions about novel social relationships.
The same ability could allow female paper wasps to spontaneously organize information during transitive inference tests, the researchers said.
Transitive inference has been regarded as a hallmark of human perception for millennia, and it has been thought to be based on logical deductions. More recently, some researchers have asked whether TI requires higher-order justification or can be solved with simpler rules.
The study by Tibbetts and her colleagues shows that paper wasps can build and manipulate an implicit hierarchy. However, no statement is made about the exact mechanisms underlying this ability.
In earlier studies, Tibbetts and her colleagues showed that paper wasps recognize individuals of their species by varying their facial markings and behave more aggressively towards wasps with unfamiliar behavior.
Researchers have also shown that paper wasps have surprisingly long memories and attribute their behavior to what they know from previous social interactions with other wasps.
Memory of quarrels: Paper wasps show a surprisingly strong memory for earlier encounters
Transitive Inference in Polistes Paper Wasps, Biology Letters royalsocietypublishing.org/doi…1098/rsbl.2019.0015
Paper wasps similar to logical thinking (2019, 7 May)
retrieved on May 7, 2019
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