Why some wasps are good with faces - and others aren't

You don't want to mess with Ms Big, so it's useful if you recognise her when you see her. So useful that even wasps can do it.

Despite having a brain less than a millionth the size of ours, queen paper wasps (Polistes fuscatus) can recognise each other's faces. Michael Sheehan and Elizabeth Tibbetts, both at the University of Michigan in Ann Arbor, think they know why.

They suspected the wasps developed the skill to keep their home in harmony. The species forms large nests with several queens, and maintaining a pecking order between them is crucial for cooperation. "If the queens know their place, it reduces aggression and keeps the peace in the colony," says Sheehan.

The nests of another related species ? Polistes metricus ? each contain a single queen, so Sheehan and Tibbetts reasoned that these queens would be bad with faces.

Maze of pain

To test the idea, they released wasps of each species, individually, into a T-shaped maze with an electrified floor. On reaching the junction, a wasp could choose to turn left or right. Along each route was one of two images of a wasp face: one of the faces always led to a safe zone where the floor wasn't electrified, the other led only to more shocks. In repeated trials, the photos and safe zone were swapped between left and right tunnels.

To avoid a shock, therefore, wasps had to tell the faces apart. P.?fuscatus queen wasps could do so after 40 trials, but those of the P.?metricus wasp never learned the skill.

The result shows that facial recognition in wasps emerged because of evolutionary pressures, say Sheehan and Tibbetts. A number of vertebrates, including our species, have the same ability. "Since wasps are so distantly related to humans, facial recognition must have evolved independently," Sheehan says.

Applying the skill in a new way taxed the wasps, however. When the researchers repeated the test using simple patterns ? triangles, cross and lines ? instead of faces, P.?fuscatus wasps required more trials to reliably recognise the "safe" pattern.

"This is bizarre," says Sheehan. "The light that bounces off a face is no different from the light of another object." Moreover, insects have compound eyes that can detect contrast and outlines, so distinguishing simple black-and-white geometric patterns should be easy. "There is something special about faces," he says.

Indeed there is. Other than recognising other queens, Stephen Hoggard at Macquarie University in Sydney, Australia, says P.?fuscatus would need to identify wasps from its own nest and distinguish them from invaders. "With multiple queens in the nest, the children will look a little different," he says. "With no facial recognition they might attempt to attack wasps from their own nest"

Journal reference: Science, DOI: 10.1126/science.1211334

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.

Have your say

Only subscribers may leave comments on this article. Please log in.

Only personal subscribers may leave comments on this article

Subscribe now to comment.

All comments should respect the New Scientist House Rules. If you think a particular comment breaks these rules then please use the "Report" link in that comment to report it to us.

If you are having a technical problem posting a comment, please contact technical support.

Source: http://feeds.newscientist.com/c/749/f/10897/s/1a945e07/l/0L0Snewscientist0N0Carticle0Cdn212320Ewhy0Esome0Ewasps0Eare0Egood0Ewith0Efaces0E0Eand0Eothers0Earent0Bhtml0DDCMP0FOTC0Erss0Gnsref0Fonline0Enews/story01.htm

texas judge texas judge tom brokaw maria shriver andy irons ethan zohn jeremy mayfield