People see faces everywhere. From the man on the moon to the potato chip that looks like Jay Leno to the bust of Jesus Christ himself singed into the side of a cheese sandwich, people can imagine faces just about anywhere. Take the following American Express commercial, for example.
There’s a good reason for this. Facial recognition is an undeniably crucial part of human evolution. Without the ability to identify each other, we’d lose all ability to form complex social networks. Telling friend from foe, debtor from indebted, or even wife from mother (too far?), would be completely impossible.
Facial recognition is so important, in fact, that it has its own special region of the brain completely devoted to the task. There’s even a difference between the wiring specially designed to recognize faces and the bits that store that information for safe keeping.
But we’re not the only social animals.
Plenty of other species that form complex social networks have been shown to also possess this ability. And now, a study from the University of Michigan has taken this idea even further by proving that even an insect can be especially wired to recognize faces.
The paper wasp (Polistes fuscatus) is a creature that lives in a very socially complex infrastructure in hives that are very well lit. Multiple queens live in the same hive, and there is a clear hierarchy of individuals who get first dibs. Being able to tell each other apart is necessary for eliminating the need for repeated posturing and battles over the right to breed.
The paper wasp’s ability to recognize faces of its own species was put to the test against a close relative, Polistes metricus, that does not have multiple queens nor a complicated pecking order. Previous studies have shown that they can’t recognize faces, while paper wasps can.
The question, however, was whether or not the paper wasps are especially hardwired to recognize the faces of their peers. After all, they could be just as good at recognizing distinct patters or the faces of the caterpillars that they eat. Maybe there’s nothing so special going on in their brain besides the ability to recognize patterns.
In order to test this theory, Michael Sheehan put the wasps in a T-shaped maze. At either end of the top of the “T” was two images. Both were either regular faces of paper wasps, faces of paper wasps disjointed by Photoshop, patterns of black and white, or faces of caterpillars. Also at one of the ends was an electric shock. By keeping the end with the electric shock consistent with the same image time after time, Sheehan could see how long it took the wasps to learn which side was safe.
While they were able to eventually get it right with the jumbled faces, patterns and caterpillar faces, they fared much better with the faces of their own kind. In each case, they were able to get up to an average of 80% correct choices in just 20 tries, which far exceeds random chance.
It also greatly exceeded the ability of its close cousin, who never quite got the hang of the tests. They never got above 70%, and even then only succeeded with patterns and caterpillar faces. They actually did worse than 50/50 when using the faces of wasps.
So what’s it all mean?
It’s interesting in and of itself that wasps have the ability to recognize each other’s faces. But this test goes one step further. It clearly shows that their tiny little brains have evolved facial recognition that exceeds the ability to recognize other patterns, just like the human brain.
However, the authors aren’t claiming that this is some sort of inherited trait that comes from a distant common ancestor millions of years ago. Instead, this is an example of convergent evolution – two species that have evolved the same ability for the same purpose, but complete independently of each other. It will be interesting to see how the tiny paper wasp’s brain manages the trick in comparison to our own.