How People Are Like Paper Wasps
How are people like paper wasps? It sounds like the introductory line of a joke, but it’s not. According to a new study from scientists at the University of Michigan, both paper wasps and people have an ability to recognize faces, because their brains, though vastly different, have evolved highly specialized face-learning mechanisms.
Don’t I know you, asked the paper wasp?
If you saw two paper wasps next to each other, chances are you couldn’t tell them apart by their faces. Paper wasps, however, seem to be able to distinguish faces. This discovery, according to Michael Sheehan, the lead author of the paper that appears in Science, marks the first time any insect has shown it has such a high level of visual learning.
Paper wasps (Polistes fuscatus), also sometimes called umbrella wasps, get their name from their habit of collecting fibers from plants and dead wood and then mixing them with saliva to make their papery nests. They are considered to be beneficial insects in that they feed on caterpillars, beetle larvae, and flies, along with nectar.
Evolutionary biologist Elizabeth Tibbetts, who worked with Sheehan on this new study, had previously shown that paper wasps can recognize others of their own species based on facial markings. Apparently paper wasps do not treat unfamiliar wasps too kindly. Paper wasps also seem to have a long memory and can remember previous interactions with other wasps.
The new study involved training paper wasps to discriminate between two different images. A total of 12 wasps underwent 40 consecutive trials on each image type, which included photos of normal paper wasp faces, caterpillars, simple geometric patterns, and computer-altered wasp faces. A reward was always associated with one image in a given pair.
The trained paper wasps could more quickly and accurately discriminate between two unaltered paper wasp photos than they could between a pair of caterpillar photos, geometric patterns, or altered wasp photos. In fact, they chose the correct unaltered paper wasp face about 75% of the time.
The scientists tried different techniques, such as using photo-editing to alter a wasp photo; for example, by removing an antennae. This type of alteration caused the wasps to do worse on facial recognition, a discovery that prompted Sheehan to note that “This shows that the way they learn faces is different than the way they seem to be learning other patterns.”
Face recognition in humans is a topic of much research, as illustrated by several recent studies. In one, published in Psychological Science, a journal of the Association for Psychological Science, the investigators noted that their findings explain, in part, “why some never forget faces, while others misrecognize their friends and relatively frequently. That’s why the research holds promise for therapies for that second category or people, who may suffer disorders such as prosopagnosia (face blindness) and autism,” according to Beijing Normal University cognitive psychologist Jia Liu.
Sheehan emphasized that “it’s important to note that we’re not claiming the exact process by which wasps learn faces is the same as humans.” Given that the brain of a paper wasp is less than one millionth the size of a human’s, that statement seems obvious. But the apparent ability of a paper wasp to recognize faces, even if only other wasps and the occasional caterpillar, may be reason to better appreciate the wonders of the natural world, along with the knowledge scientists can gain regarding the human brain and function.
Association for Psychological Science
Sheehan MJ, Tibbetts EA. Current Biology 2008 Sep 23; 18(18): R851-52
Tibbetts EA. Proceedings. Biological Sciences 2002 Jul 22; 269(1499): 1423-28
University of Michigan news release
Picture credit: Wikimedia Commons