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The
Smithsonian Magasine by Carl Zimmer
On
the front porch of an old Coast Guard station on Appledore
Island, seven miles off the southern coast of Maine, Thomas
Seeley and I sat next to 6,000 quietly buzzing bees. Seeley
wore a giant pair of silver headphones over a beige baseball
cap, a wild fringe of hair blowing out the back; next to him
was a video camera mounted on a tripod. In his right hand,
Seeley held a branch with a lapel microphone taped to the
end. He was recording the honeybee swarm huddling inches
away on a board nailed to the top of a post.
Seeley, a biologist from Cornell
University, had cut a notch out of the center of the board
and inserted a tiny screened box called a queen cage. It
housed a single honeybee queen, along with a few attendants.
Her royal scent acted like a magnet on the swarm.
If I had come across this swarm
spread across my back door, I would have panicked. But here,
sitting next to Seeley, I felt a strange calm. The insects
thrummed with their own business. They flew past our faces.
They got caught in our hair, pulled themselves free and kept
flying. They didnt even mind when Seeley gently swept
away the top layer of bees to inspect the ones underneath.
He softly recited a poem by William Butler Yeats:
I will arise and go now, and go to
Innisfree,
And a small cabin build there, of
clay and wattles made:
Nine bean-rows will I have there, a
hive for the honey-bee,
And live alone in the bee-loud
glade.
A walkie-talkie on the porch rail
chirped.
Pink bee headed your
way, said Kirk Visscher, an entomologist at the
University of California, Riverside. Seeley, his gaze fixed
on the swarm, found the walkie-talkie with his left hand and
brought it to his mouth.
We wait with bated
breath, he said.
Sorry? Visscher
said.
Breath. Bated. Over.
Seeley set the walkie-talkie back on the rail without taking
his eyes off the bees.
A few minutes later, a honeybee
scout flew onto the porch and alighted on the swarm. She
(all scouts are female) wore a pink dot on her
back.
Ah, here she is. Pink has
landed, Seeley said.
Pink was exploring the island in
search of a place where the honeybees could build a new
hive. In the spring, if a honeybee colony has grown large
enough, swarms of thousands of bees with a new queen will
split off to look for a new nest. It takes a swarm anywhere
from a few hours to a few days to inspect its surroundings
before it finally flies to its newly chosen home. When Pink
had left Seeleys swarm earlier in the morning, she was
not yet pink. Then she flew to a rocky cove on the northeast
side of the island, where she discovered a wooden box and
went inside. Visscher was sitting in front of it under a
beach umbrella, with a paintbrush hanging from his lips.
When the bee emerged from the box, Visscher flicked his
wrist and caught her in a net the size of a ping-pong
paddle. He laid the net on his thigh and dabbed a dot of
pink paint on her back. With another flick, he let her
go.
Visscher is famous in honeybee
circles for his technique. Seeley calls it alien abduction
for bees.
As the day passed, more scouts
returned to the porch. Some were marked with pink dots.
Others were blue, painted by Thomas Schlegel of the
University of Bristol at a second box nearby. Some of the
returning scouts started to dance. They climbed up toward
the top of the swarm and wheeled around, waggling their
rears. The angle at which they waggled and the time they
spent dancing told the fellow bees where to find the two
boxes. Some of the scouts that witnessed the dance flew away
to investigate for themselves.
Then a blue bee did something
strange. It began to make a tiny beeping sound, over and
over again, and started head-butting pink bees. Seeley had
first heard such beeps in the summer of 2009. He didnt
know why it was happening, or which bee was beeping.
All I knew was that it existed, he said. Seeley
and his colleagues have since discovered that the beeps come
from the head-butting scouts. Now Seeley moved his
microphone in close to them, calling out each time the bee
beeped. It sounded like a mantra:
Blue…blue…blue…blue…blue.
When you consider a swarm one bee at
a time this way, it starts to look like a heap of chaos.
Each insect wanders around, using its tiny brain to perceive
nothing more than its immediate surroundings. Yet, somehow,
thousands of honeybees can pool their knowledge and make a
collective decision about where they will make a new home,
even if that home may be miles away.
The decision-making power of
honeybees is a prime example of what scientists call swarm
intelligence. Clouds of locusts, schools of fish, flocks of
birds and colonies of termites display it as well. And in
the field of swarm intelligence, Seeley is a towering
figure. For 40 years he has come up with experiments that
have allowed him to decipher the rules honeybees use for
their collective decision-making. No one has reached
the level of experimentation and ingenuity of Tom
Seeley, says Edward O. Wilson of Harvard
University.
Growing up in Ellis Hollow, in
upstate New York, Seeley would bicycle around the farms near
his house; one day he discovered a pair of white boxes. They
each contained a hive. Seeley was seduced. He came back day
after day to stare at the hives. He would look into the
boxes and see bees coming in with loads of pollen on their
legs. Other bees fanned their wings to keep the hives cool.
Other bees acted as guards, pacing back and forth at the
opening.
If you lie in the grass in
front of a hive, you see this immense traffic of bees
zooming out of the hive and circling up and then shooting
off in whatever direction they want to go, said
Seeley. Its like looking at a meteor shower.
For his PhD at Harvard, Seeley took
up a longstanding entomological question: How do honeybees
choose their homes? He climbed into trees and poured cyanide
into hives to kill the honeybees inside. He sawed down the
trees and measured the cavities. Seeley found that bee hive
hollows were very much alike. They were at least ten gallons
in volume, sat at least 15 feet off the ground and had a
narrow opening.
Seeley built 252 wooden boxes of
different shapes and sizes and scattered them in forests and
fields to test how particular bees were about these
qualities. Swarms only moved into boxes that had the same
features that Seeley had found in their tree cavities.
Its really important to get them all
right, Seeley said.
The architectural tastes of
honeybees are not mere whims. If honeybees live in an
undersized cavity, they wont be able to store enough
honey to survive the winter. If the opening is too wide, the
bees wont be able to fight off invaders.
He took his research to Appledore
Island because no native honeybees live here, and it has no
big trees where the insects could make their homes. Seeley
and his colleagues would bring their own honeybees and nest
boxes. This is our laboratory, Seeley said.
This is where we gain control.
In one experiment, Seeley set up
five boxes of different sizes. Four of the boxes were
mediocre, by honeybee standards, while one was a dream home.
In 80 percent of the trials, the swarms chose the dream
home.
Through years of study, Seeley and
his colleagues have uncovered a few principles honeybees use
to make these smart decisions. The first is enthusiasm. A
scout coming back from an ideal cavity will dance with
passion, making 200 circuits or more and waggling violently
all the way. But if she inspects a mediocre cavity, she will
dance fewer circuits.
Enthusiasm translates into
attention. An enthusiastic scout will inspire more bees to
go check out her site. And when the second-wave scouts
return, they persuade more scouts to investigate the better
site.
The second principle is flexibility.
Once a scout finds a site, she travels back and forth from
site to hive. Each time she returns, she dances to win over
other scouts. But the number of dance repetitions declines,
until she stops dancing altogether. Seeley and his
colleagues found that honeybees that visit good sites keep
dancing for more trips than honeybees from mediocre
ones.
This decaying dance allows a swarm
to avoid getting stuck in a bad decision. Even when a
mediocre site has attracted a lot of scouts, a single scout
returning from a better one can cause the hive to change its
collective mind.
Its beautiful when you
see how well it works, Seeley said. Things
dont bog down when individuals get too stubborn. In
fact, theyre all pretty modest. They say, Well,
I found something, and I think its interesting. I
dont know if its the best, but Ill report
what I found and let the best site
win.
During the time I visited Seeley, he
was in the midst of discovering a new principle. Scouts, he
found, purposefully ram one another head-on while deciding
on a new nest location. They head-butt scouts coming from
other locationspink scouts bumping into blue scouts
and vice versacausing the rammed bee to stop
dancing.?As more scouts dance for a popular site, they also,
by head-butting, drive down the number of dancers for other
sites.
And once the scouts reach a quorum
of 15 bees all dancing for the same location, they start to
head-butt one another, silencing their own side so that the
swarm can prepare to fly.
One of the things Seeley has been
thinking about during his vigils with his swarms is how much
theyre like our own minds. I think of a swarm as
an exposed brain that hangs quietly from a tree
branch, Seeley said.
A swarm and a brain both make
decisions. Our brains have to make quick judgments about a
flood of neural signals from our eyes, for example, figuring
out what were seeing and deciding how to
respond.
Both swarms and brains make their
decisions democratically. Despite her royal title, a
honeybee queen does not make decisions for the hive. The
hive makes decisions for her. In our brain, no single neuron
takes in all the information from our senses and makes a
decision. Millions make a collective choice.
Bees are to hives as neurons
are to brains, says Jeffrey Schall, a neuroscientist
at Vanderbilt University. Neurons use some of the same
tricks honeybees use to come to decisions. A single visual
neuron is like a single scout. It reports about a tiny patch
of what we see, just as a scout dances for a single site.
Different neurons may give us conflicting ideas about what
were actually seeing, but we have to quickly choose
between the alternatives. That red blob seen from the corner
of your eye may be a stop sign, or it may be a car barreling
down the street.
To make the right choice, our
neurons hold a competition, and different coalitions recruit
more neurons to their interpretation of reality, much as
scouts recruit more bees.
Our brains need a way to avoid
stalemates. Like the decaying dances of honeybees, a
coalition starts to get weaker if it doesnt get a
continual supply of signals from the eyes. As a result, it
doesnt get locked early into the wrong choice. Just as
honeybees use a quorum, our brain waits until one coalition
hits a threshold and then makes a decision.
Seeley thinks that this convergence
between bees and brains can teach people a lot about how to
make decisions in groups. Living in groups,
theres a wisdom to finding a way for members to make
better decisions collectively than as individuals, he
said.
Recently Seeley was talking at the
Naval War College. He explained the radical differences in
how swarms and captain-dominated ships make decisions.
They realize that information is very distributed
across the ship, Seeley said. Does it make sense
to have power so concentrated? Sometimes you need a fast
decision, but theres a trade-off between fast versus
accurate.
In his experience, Seeley says, New
England town hall meetings are the closest human grouping to
honeybee swarms. There are some differences, but there
are also some fundamental similarities, he said. Like
scouts, individual citizens are allowed to share different
ideas with the entire meeting. Other citizens can judge for
themselves the merit of their ideas, and they can speak up
themselves. When its working properly, good
ideas rise up and bad ones sink down, says
Seeley.
Groups work well, he argues, if the
power of leaders is minimized. A group of people can propose
many different ideasthe more the better, in fact. But
those ideas will only lead to a good decision if listeners
take the time to judge their merits for themselves, just as
scouts go to check out potential homes for
themselves.
Groups also do well if theyre
flexible, ensuring that good ideas dont lose out
simply because they come late in the discussion. And rather
than try to debate an issue until everyone in a group
agrees, Seeley advises using a honeybee-style quorum.
Otherwise the debate will drag on.
One of the strengths of honeybees is
that they share the same goal: finding a new home. People
who come together in a democracy, however, may have
competing interests. Seeley advises that people should be
made to feel that they are part of the decision-making
group, so that their debates dont become about
destroying the enemy, but about finding a solution for
everyone. That sense of belonging can be
nurtured, Seeley said. The more we fashion our
democracies after honeybees, Seeley argues, the better off
well be.
Thomas
Seeley – Cornell University
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