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.
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| 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:
.jpg) |
| 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!
References:
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:
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