Here is a pop quiz for you. Tom is taller than Dick. Dick is taller than Harry. Who is taller, Harry or Tom?
If you said Tom, congratulations! He has just demonstrated what is called "transitive inference": the ability to compare things indirectly, based on previous juxtapositions. But before giving yourself too much patting on the back, you should know that this ability was recently demonstrated by another creature: The humble paper wasp that could be living in your backyard right now.
In the summer of 2017, researchers at the University of Michigan submitted two species of paper wasps through a transitive inference test. A statistically significant portion of the time, wasps pbaded. Other animals, including rats, geese and cichlid fish, have also exhibited this ability. But this study, which was published on Tuesday in Biology Letters, is the first to successfully exhibit it in an invertebrate (bees did not pbad a similar test in 2004).
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Paper wasps are found on all continents except Antarctica. You could be near some at this time. "They tend to nest in the eaves of the houses or in grills," said Elizabeth Tibbetts, lead author of the study.
In In a previous study, Dr. Tibbetts showed that individual female wasps can be identified by their different facial patterns, which resemble Rorschach ink spots. "When two wasps meet, they learn:" Oh, that's what Suzy looks like, "he said. "And the next time they meet, they remember who Suzy is."
In the spring, the females spend a lot of time fighting, coming face to face and exchanging slaps with their appendages. These confrontations resemble fights in the school playground. "Some wasps will be fighting; Some wasps will be watching the fights, "Dr. Tibbetts said." It's a very exciting time. "Wasps remind winners and losers, and use them to establish a social hierarchy: the strongest reproduce, while the more weak do all the work.
Dr. Tibbetts and her colleagues wanted to see if the wasps could take this a step further. Let's say a particular paper wasp beat Suzy, and then he was in the ring a few days later when Suzy hit Jane. Could that wasp realize that she probably would also be better Jane?
Such knowledge would require transitive inference. So the team went on to what is called a "five-element training procedure", which is now a standard way to test this skill in animals. They put the wasps in a series of two-color cameras. If they moved to the wrong color, they received a slight electric shock. In this way, "you train them so that blue is better than green, and once they learn that, you train them so that green is better than purple," said Dr. Tibbetts. They did it for four pairs of five colors.
After the wasps had been trained, they were placed in a new chamber. This one had colors that they were familiar with in training, but that had not been matched before. About 67 percent of the time, wasps successfully chose the "best" color, the one that is least likely to shock them.
"They are organizing all those pairs in a linear hierarchy in their heads," said Dr. Tibbetts. Next, he plans to study how wasps really use this skill during social interactions.
Colin Allen, a cognitive philosopher at the University of Pittsburgh, warns against excessive interpretation of the study, saying that the simplicity of the test makes it "difficult to judge what processes are operating in these wasps." But he calls it "an important reminder" that bees can not do something, it does not necessarily mean that no insect can do it.
It fits well with another of the lessons of the study: just because humans can do something does not necessarily mean that not all insects can do it.