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Have you ever known someone who was "good at faces"? The kind of guy who can instantly recognize someone he barely met a year ago?

In the insect world, some paper wasp species are a lot like that guy, and a new UA study published this month in the journal Brain, Behavior and Evolution, says that the brains of wasps that can discriminate between individuals work differently from those that cannot.

The goal of the study was "to find something in their brains that was different," said Wulfila Gronenberg, associate professor of neurobiology and ecology and evolutionary biology at the University of Arizona, and one of the authors of the paper.

He said that much as bats use sound to navigate and have an enlarged area of the brain for processing sound, and birds have an enlarged memory portion of their brains to find the seeds they hide, wasps that can tell each other apart might have different kind of brains from those that can't.

The research has implications for how human brains function, because in some basic ways insect brains are very similar to those of more complex animals, including humans.

Gronenberg, whose main focus is bumblebees, became interested in wasp visual systems and how their brains work in 2005, after Elizabeth Tibbetts, then a postdoctoral fellow at UA, published a paper on wasp facial recognition. Tibbetts is now an assistant professor of ecology and evolutionary biology at the University of Michigan.

Her paper was on a type of paper wasp, P. dominulus, that judges the strength and identity of other wasps in the colony by the number of black spots on their bodies, and has "relatively sophisticated facial recognition," Tibbetts said. The black spots are like a black belt for the wasps, she said, with more spots indicating a stronger wasp.

In her experiment, she changed the pattern on some wasps and observed that the insects "had trouble figuring out who was stronger, and spent more time fighting." The "liars" were treated very aggressively, regardless of whether they were stronger than their spots seemed to indicate or weaker.

"Nobody thought that insects with tiny brains would be able to do that," Gronenberg said.

The wasps also use this visual acumen to find food and navigate their way back to the hive after foraging.

"Social insects usually use smell," Gronenberg said, "but do not recognize individuals." Instead smells are simply used to determine who is part of the hive and who isn't.

The new experiment involved P. dominulus and P. fuscatus, the wasps that are able to tell each other apart by their facial markings, compared with two species of paper wasps without the visual ability.

The brains of the wasps were thinly sliced and placed onto slides. Drawings of the slides were made. "The drawings were used to calculate the volume of the brain structures," said Gronenberg, and then compared to the other wasps statistically.

Rather than having enlarged brains, or enlarged parts of brain to deal with visual signals, the wasps that use sight for facial recognition had a smaller part of the brain for dealing with smells, the antennal lobe. However, the mushroom body subcompartments, which integrate information from the senses and help control learning and memory, were not any larger — as researchers thought they might be.

Essentially, it's not a matter of different brain structure that enables some wasps to tell faces apart while other cannot. The ability "is already there in all wasps, it just needs a little twitch," Gronenberg said. The visual ability might be related just to telling apart patterns in general and then applied by these wasps to tell faces apart. "You don't need much modification to do that," he said.

"Insects are more complicated than we give them credit for," Tibbetts said.

In fact, research on insect brains informs a lot of what is known about human brains. "The information on smell in humans comes from insects," Gronenberg said. The nerve cells function identically, so one "couldn't tell if it comes from a human, monkey or insect."

Structurally, of course, human brains are more complicated. "Humans have a part of their brain just for recognizing faces," Tibbetts said. If this part of the brain is harmed, people get "face blindness," in which they are totally unable to tell one face from another. Recent studies have indicated that face blindness can occur in not only humans and apes, but sheep as well, Tibbetts said.

Gronenberg is continuing to research bumblebee brains and the learning patterns of larger bees with larger brains. Tibbetts is working on testing the memory of wasps, including how well and how long they can remember.

• There are about 75,000 species of wasps. This study looked at four of them.

• There are two general kinds of wasps — solitary wasps and social wasps. Only social wasps make nests.

• Paper wasps are so called because they use dead wood and plant stems mixed with saliva to construct their nests, which look as though they're made of paper. They are sometimes called umbrella wasps because of the shape of their nests.

• Paper wasps secrete a chemical around the base of their nests to keep ants away.

• Wasps in Tucson include the tarantula hawk wasp and the velvet ant.

Source: Pima Community College and about.com