Like humans, the paper wasp has a special talent for learning faces

Like humans, the paper wasp has a special talent for learning faces
Polistes fuscatus paper wasps have extremely variable facial patterns that they use to recognize each other as individuals. This montage displays some of the variation seen in female paper wasp faces in this species. Credit: Michael Sheehan

Though paper wasps have brains less than a millionth the size of humans', they have evolved specialized face-learning abilities analogous to the system used by humans, according to a University of Michigan evolutionary biologist and one of her graduate students.

" and humans have independently evolved similar and very specialized face-learning mechanisms, despite the fact that everything about the way we see and the way our brains are structured is different," said graduate student Michael Sheehan, who worked with Elizabeth Tibbetts on the face-recognition study. "That's surprising and sort of bizarre."

The study marks the first time that any insect has demonstrated such a high level of specialized visual learning, said Sheehan, lead author of a paper on the topic scheduled for online publication in the journal Science on Thursday, Dec. 1.

In earlier research, Tibbetts showed that paper wasps (Polistes fuscatus) recognize individuals of their species by variations in their facial markings and that they behave more aggressively toward wasps with unfamiliar faces.

In 2008, Sheehan and Tibbetts published a paper in demonstrating that these wasps have surprisingly long memories and base their behavior on what they remember of previous social interactions with other wasps.

In their latest study, Sheehan and Tibbetts tested learning by training wasps to discriminate between two different images mounted inside a T-maze, with one image displayed at each end of the top arm of the T.

Like humans, the paper wasp has a special talent for learning faces
Like humans, Polistes fuscatus paper wasps recognize individuals by their unique facial patterns. This photo shows a paper wasp queen on an early nest. Credit: Michael Sheehan

Twelve wasps were trained for 40 consecutive trials on each image type. The paired images included photos of normal paper wasp faces, photos of caterpillars, simple , and computer-altered wasp faces. A reward was consistently associated with one image in a pair.

The researchers found that the , which are generalist visual predators of caterpillars, were able to differentiate between two unaltered P. fuscatus faces faster and more accurately than a pair of caterpillar photos, two different geometric patterns, or a pair of computer-altered wasp faces. They learned to pick the correct unaltered wasp face about three-quarters of the time.

Two simple black-and-white geometric patterns should have been easy for the wasps to distinguish, because the insects' compound eyes are good at detecting contrast and outlines, Sheehan said. Yet the wasps learned complicated face images more rapidly than the geometric patterns.

At the same time, introducing seemingly minor changes to a P. fuscatus facial image -- by using a photo-editing program to remove a wasp's antennae, for example -- caused test subjects to perform much worse on the facial recognition test.

"This shows that the way they learn faces is different than the way they seem to be learning other patterns. They treat faces as a different kind of thing," Sheehan said.

"Humans have a specialized face-learning ability, and it turns out that this wasp that lives on the side of your house evolved an analogous system on its own," he said. "But it's important to note that we're not claiming the exact process by which wasps learn faces is the same as humans."

The ability to recognize individuals is important to a species like P. fuscatus, in which multiple queens establish communal nests and raise offspring cooperatively, but also compete to form a linear dominance hierarchy. Remembering who they've already bested -- and been bested by -- keeps individuals from wasting energy on repeated aggressive encounters and presumably promotes colony stability by reducing friction.

Sheehan also tested a closely related species of wasp, P. metricus, which lacks the varied facial markings of the paper wasp and lives in colonies controlled by a single queen. In the T-maze test, P. metricus scored no better than chance when asked to distinguish between individuals of its own species.

"Differences in face learning between the two species cannot be attributed to general differences in visual learning, as both species learned to discriminate between pairs of artificial patterns and caterpillars at the same rate and with the same accuracy," Sheehan and Tibbetts wrote. "P. fuscatus and P. metricus differed only in their ability to learn normal face stimuli."

"The evolutionary flexibility of specialized face learning is striking and suggests that specialized cognition may be a widespread adaptation to facilitate complex behavioral tasks such as individual recognition," they wrote.

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Dec 01, 2011
Not surprising at all, like I said before, my local wasps even recognize the difference between my roommate and I, because I take them outside and he kills them. In return for that, he gets stung, and when they see me, they fly to the door and wait for me to open it. I don't even have to pick them up and take them out anymore.

Dec 01, 2011
You are extremely adept at interspecies communication, Isaacsname, and your bird experiences are inspiring. I admire spiders and bring them outside gingerly. I can't read any gratitude on their tiny faces, but saving the lives of these brilliant engineers is gratifying. I think, one day, organisms the size of volvox and hydra will reveal more to us than they let on today.

Dec 01, 2011
Thanks friend

I really do feel ,..blessed, in a sense, to have had the experiences with nature that I have so far. Some have reached beyond profound, to the point that it left me wondering if I had them at all, they're not something one discusses freely with other people, as most have no common experiences to relate.

It's funny that people overlook one little thing about any attempt at inter-species friendships, it's mainly about our sizes. It sounds silly to people when I try to explain you can't just reach out your window, hold out your hand and have a bird land on it. If a bird who happened to be 100's or 1000's of times my size even looked at me with mild curiosity, I'd get nervous, they do the same thing. You seal the friendship deal eventually with your eyes though, it works with squirrels, birds, cats, monkeys, whatever. I'll make some videos this winter and spring of some of the things I'm doing and put them up on YT, It's not an approach any research has ever taken :D

Dec 01, 2011
I look forward to seeing those videos. One day, consciousness will be made visible, and a newfound respect for all living things will be had.

Dec 02, 2011
@David McC-
It's from my own first hand experiences that I make statements that are beyond your understanding. I wouldn't bother to try and convince you of anything, it would be a waste of time, but Isaacsname and I can attest to natural phenomena one doesn't learn inside a lab. You should get out more and open your eyes, ears, and mind. You're acting like a frustrated English boarding school brat.

Dec 02, 2011
Well, when you say " universal consciousness " , what exactly do you mean ? I don't think that all things are having the same conscious experience, merely that they are all conscious and having experiences.

If I think about what consciousness is like for other life that may exist in other places in the universe, I can only say that I am of the belief it is similar throughout the cosmos. Things like humor, anger, love, etc, I'm certain that they exist and are experienced in the same basic way everywhere. Just because something like love may be explainable entirely by chemistry and based only on electrical signaling, it does not diminish the love that one feels, even if they are aware of the fact it is biochemical.

Do bugs tell jokes ? No, I'm not that out there David, but if you'd had the same past 39 years as me, you'd likely have a very different view of the world around you.

To each their own :D


Dec 02, 2011
@ Isaacsname:

In the video, was that a Ford Falcon?

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