Wasps and humans don’t have much in common, but a University study published yesterday in the journal Science ties them together in an unexpected biological way.
The study, authored by Rackham student Michael Sheehan and Elizabeth Tibbetts, assistant professor of ecology and evolutionary biology, links the evolution of specialized face-learning mechanisms of humans and wasps. The paper suggests paper wasps — a species also called umbrella wasps — learn the faces of fellow wasps with mechanisms different from those used to identify other objects. This is the first study to show such a high level of specialized facial-recognition in insects, Sheehan said.
Sheehan and Tibbetts began the study in 2008 when they developed a new method for training wasps. The technique was the basis for their study, in which they attached varying image pairs to the fork of a T-shaped maze. The images included different paper wasp faces, caterpillar faces, shapes and computer-altered wasp faces.
In each trial, Sheehan and Tibbetts arbitrarily selected which of the two images would be the “correct” choice and applied a mild shock when a wasp touched the “incorrect” image. Sheehan and Tibbetts trained 12 wasps for each pair of images, and each wasp participated in 40 consecutive trials for the same set of images.
The results indicated that the wasps chose the “correct” image of an unaltered wasp face about three-fourths of the time — significantly more often than between two images of geometric shapes, caterpillar faces and computer-altered paper wasp faces.
The team said the results surprised them, even though they published a study in 2008 in which they found that paper wasps have good memories and base their relations with other wasps off of past interactions.
“We figured that they would be able to learn faces,” Sheehan said. “We didn’t have a clear expectation that they would be so good at it. That was surprising.”
Tibbetts said the wasps’ ability to learn faces was so shocking that they conducted the experiment additional times after seeing the initial results.
Tibbetts said she was surprised to find that the wasps had significantly more trouble learning computer-altered wasp faces, which had their antennas taken out, than they did learning the unaltered faces. She hypothesized that it might suggest paper wasps use antennas to identify other wasps in the same way that humans use eyes as identifiers.
According to Sheehan, the study’s significance was further realized when the experiment was repeated with a different wasp species. This separate species was unable to distinguish between the images and seemed to select them at random. Sheehan said he believes the paper wasp developed the capability — while the other species did not — because paper wasps have multiple queens per nest and must recognize faces to distinguish hierarchy.
“What’s cool about this is that we show that humans and wasps, they have very similar mechanisms,” Sheehan said. “But when you compare these two species of wasps that are really similar — more similar in their lifestyles than humans and chimpanzees are — they are totally different in the way they’re able to learn … Evolution has shaped not just that they’re better or worse at learning visual things but that they’re better at learning faces. It’s kind of bizarrely specific.”
Sheehan said the study could be the starting point for further exploration of evolutionary facial recognition development in humans.
“It sets up an interesting system of studying cognition,” he said. “It might tell us what aspects of specialization in humans are specific to humans.”
Sheehan added that he did not know how or, biologically speaking, why the wasps developed the specialized cognition. Sheehan said this question might be an area for future research.
Tibbetts added that another possibility could be to further study the nature of the specialized mechanism for face learning and the differences between the two wasp species.