Written by: Erin Wojan
Panic! That’s the feeling that consumes us when someone we don’t recognize says “hi” and begins a conversation. We search the crypts of our memory to recall if this rando is actually a friend with a new haircut and before we know it, we fumble our words and have responded, “Good. How are you?” when in reality, they never even asked. Just as discomforting but on the other side of it, we’ve all been that weirdo that tries to wave at a friend only to realize that it wasn’t who we thought it was. We shake it off and give a good effort to pretend like we were stretching or some other completely unrealistic gesture in order to keep it cool.
We’ve become so skilled at facial recognition that it catches us by surprise when these awkward situations happen to us. This capability is due in part to our advanced vision, which relays visual stimuli to our brains. Images are interpreted in specific brain regions and this allows us to recognize faces as such and then differentiate between all of them.
But we’re not the only ones who can recognize faces. What if I told you that the wasp buzzing around your door, plotting its revenge against you in honor of its friend that you just drowned in wasp spray, can recognize your face as well?
Well you’re right… I’d be lying.
However it isn’t too much of stretch for the paper wasp, Polistes fuscatus, who are able to recognize and remember each other’s faces using different facial markings as indicators. These wasps have highly variable facial marking as seen in the photo to the right. To explore this idea of recognition and the reason for the wasps’ facial markings, Elizabeth Tibbetts actually painted their faces differently to observe if they were still recognized and accepted in their colonies or whether they received more aggression than normal. And no, I don’t mean she put a smiley face or rainbow on their cheeks. Tibbetts manipulated the color patterns and found that wasps whose yellow coloration that was altered with paint did receive more aggression from nest mates than wasps whose markings weren’t changed. On top of this, the aggression declined towards the painted wasps as they became more familiar to their nest mates, suggesting the wasps remembered their new member.
|A variety of Polistes fuscatus paper wasp faces|
With this intriguing idea, Tibbetts and her previous graduate student, Michael Sheehan, took this idea one step further and found that these wasps base their behavior on previous social interactions with other wasps that they remember. They introduced two new paper wasps to each other on the first day of their experiment. Subsequently, the focal wasps were then separated into two different communal cages each containing ten wasps they had no previous association with. These focal wasps were then introduced to a second round of new wasps a few days later, now providing a large variety of patterns for them to learn and potentially “forget” the faces seen on day 1. The focal wasps were finally reintroduced to the wasps that they encountered on the first day of their experiment. If the wasps have an ability to differentiate between each other and can base their behavior off previous interactions, the aggression of the focal wasps should be less on day 7 when they encounter a “familiar” wasp as opposed to days 1 and 6 when they interacted with a new wasp for the first time. Not surprisingly, this result is exactly what they found! Even after a week of interactions with other wasps, the two original wasps showed a reduced aggression towards each other leading to an impressive demonstration of a social memory in this insect.
For an overview, watch this video:
So no you’re wondering, “Why and how is this possible?”
Well let me spit some more knowledge on you:
|An eye map of a closely related paper wasp, Polistes bahamensis|
While the mechanics are still being explored and no claims have compared this adaptation to the human mechanism, some ideas have been formulated as to why these wasps are so dang special. To start off, their social hierarchy is a little different from their closely related kin. P. fuscatus wasps live in colonies that have multiple queens meaning that the ability to distinguish each other might be more beneficial in fitness. Recognizing one another allows the wasps to remember competition success as far as who has beaten who and who has a higher ranking, all while trying to become the most dominant. Without this level of recognition, aggression levels would be much higher as they are all competing for dominance.
To better distinguish victors from losers, these paper wasps might have higher-acuity zones in their eyes allowing for better vision to identify each other. Similar to other insects, they have compound eyes that are full of photoreceptor cells. With larger eyes, more light enters that can be focused, providing sharper vision. We would expect to see this relationship in paper wasps, as their need for better vision to maintain social hierarchy implies they should have larger eyes than similar species. Sheehan decided to test this idea by looking at 19 species of paper wasps from both the wild and museum collections and found that the eyes of wasps with unique facial patterns have larger eyes compared to the wasps without facial markings. Evolutionarily, these wasps have improved their visual acuity despite their smaller size, in order to discriminate between each other.
So now the next time you make a fool of yourself by waving at someone you don’t actually know, think back to this blog and realize that these wasps are way cooler than you and I! Distinguishing each other by facial markings and using it in their social interactions is a big deal for these tiny insects and I can’t wait to see what else researchers find out about them!
Handwerk, Brian. "Wasps Can Recognize Faces." National Geographic. National Geographic Society, 2 Dec. 2011. Web. 28 Jan. 2015.
Sheehan, M. J. and E. A. Tibbetts. 2008. Robust long-term social memories in paper wasp. Current Biology 18: 851-852.
Sheehan, M. J., J. Jinn, E. A. Tibbetts. 2014. Coevolution of visual signals and eye morphology in Polistes paper wasps. Biology Letters 10(4).
Sanders, Robert. "Among Wasps, Bigger Eyes Evolved the Better to See Social Cues." UC Berkeley NewsCenter. 29 Apr. 2014. Web. 28 Jan. 2015.
Tibbetts, E. A. 2002. Visual signals of individual identity in the wasp Polistes fuscatus. The Royal Society 269: 1423-1428.
Video and Images: