PANAMA -- SPECIAL FROM PANAMA"
Echoes in the Night
Bridge that Changed the World
ALAN ALDA On this edition of Scientific
American Frontiers, we're on our way to the wild rainforests
ALAN ALDA (Narration) We'll find out how bees talk,
and ants run forest farms. We'll try to save the Panama Canal
-- in the kitchen.
ALAN ALDA Rat soup!
ALAN ALDA (Narration)
We'll enter the forest at night.
ELISABETH KALKO It's a whole
symphony of bat calls that's around us right now.
(Narration) And we'll see how the world changed -- when Panama
formed just a few million years ago.
ALAN ALDA I'm Alan Alda,
join me now -- exploring Panama.
back to top
ALAN ALDA For this episode of Scientific American Frontiers,
we're in Panama. And here's Panama's most famous feature,
the Panama Canal. But it was the building of the canal that
led to the creation of something else here, that for scientists
may be even more famous -- and that's Barro Colorado Island.
The island's a mecca for scientists from all over the world,
who come here to study the wonderful intricacies of tropical
forests. How thousands of different plants and animals, insects,
birds, bats, trees, get along together. And how they're connected.
Actually this whole show is about connections. Like how the
canal created the island, but also brought in a terrible alien
grass that only now is beginning to be beaten back. And how
millions of years ago the formation of the Isthmus of Panama
itself intensified the Gulf Stream, changed the climate of
Europe and Africa, and maybe even caused human beings to evolve.
Quite a record for a small country. So now let's plunge into
ALAN ALDA (Narration) To get to Barro Colorado
Island, there's no better way than along the canal...Although
that can be a bit of a squeeze. The canal opens out into Lake
Gatun. It's a twenty-three mile long fresh water lake, designed
to form the canal's middle section, and created just eighty
ALAN ALDA What happened to all the trees and everything
that were flooded?
ANTHONY COATES Well, they would just drown,
and then they died, and now their, their ghostly sort of stumps
are left throughout the lake. In fact for our scientists and
our park rangers, we have a constant problem with boaters
being wrecked by running over the stump of a tree.
(Narration) Without mishap, here we are at Barro Colorado
Island. And here, nestled in the trees, is the Smithsonian
Tropical Research Institute, known to everyone as "STRI".
ANTHONY COATES Hello, David.
ALAN ALDA (Narration) David Roubik is STRI's resident bee
expert. We'll be looking at his wonderful discoveries later.
ALAN ALDA How unusual is this place in
the whole world?
ANTHONY COATES It's pretty much unique because
of the sophistication of its facilities, and the primary protected
nature of the forest.
ALAN ALDA (Narration) And here's STRI's
forest laboratory. Protected as a national park, uninhabited,
and unexploited -- except by scientists. It's just three miles
by two, covered with a riot of tropical growth, spilling down
to the edge of the lake. What fascinates scientists about
all the world's tropical forests is their amazing diversity.
Take trees, for instance, the basic building blocks of the
ALAN ALDA If you walk around in a square mile here,
how many different kinds of species are you liable to come
ANTHONY COATES You could probably describe the entire
Appalachian Forest from Maine to Alabama with thirty different
species. We have what we call a fifty hectare plot, that's
five football fields by ten football fields. It contains 330
species of tree.
ALAN ALDA (Narration) Lots of different kinds
of tree, and, lots of everything else, too. Well there are
only twenty-one kinds of large animal on the island -- these
are howler monkeys -- because it's too small an area for more.
But how about the little things? There are a few hundred kinds
of ant, for example. Or take bees -- there are dozens of kinds,
just on Barro Colorado. We're a long way from understanding,
or even identifying, everything that's small in tropical forests.
The talk in the STRI cafeteria is not about the food, it's
all about what's going on out there in the forest. And lately,
thanks to this talented young Rearcher, Elisabeth Kalko, it's
the forest at night that's come alive. She's an expert on
Barro Colorado's bats...
IN THE NIGHT
ALAN ALDA (Narration) Night falls on Barro Colorado
Island -- but the forest doesn't sleep. It's time for the
island's bats to swing -- quietly -- into action. But a few
bats will have their hunting briefly interrupted by Elisabeth
Kalko's mist nets. One of the world's leading bat experts,
she's identified over seventy different bat species, just
on the island.
ELISABETH KALKO This is a round-eared bat and
it has very large ears here, and it's actually a pregnant
female, when I touch her belly I can feel the embryo. And
it also belongs to the leaf-nose bats and has this little
funny leaf-nose on its snout, and rather large eyes. It's
also a little carnivore. It eats insects and has been reported
also to catch birds.
ALAN ALDA (Narration) Here's another
kind of leaf-nose bat. This one's also a carnivore, but eats
fruit and nectar, too. It's one of the forest's best flyers.
ELISABETH KALKO Bats fly with their hands, here this is the
thumb, with the little claw on it, and then here you see the
elongated fingers, and between the fingers there's this rubber-like
membrane. This bat has enormous wings, a large wing span,
and it's a very fast flyer. It flies huge distances every
night, and you may sometimes see it above the canopy, hunting
for insects in the air.
ALAN ALDA (Narration) This is the
round-eared bat Elisabeth caught tonight. She and her graduate
student will use a tiny transmitter that broadcasts differently
when it's upside down -- so they'll be able to tell when the
bat's resting. There's a delicate procedure to glue the transmitter
ELISABETH KALKO That looks great.
ALAN ALDA (Narration)
How long it'll stay depends on this particular guy's personal
ELISABETH KALKO We have a lot of bats that are really
grooming a lot and sometimes we loose the transmitter after
one night, but occasionally we find bats that carry the transmitter
several weeks. We have right now a bat that carries the transmitter
now for three weeks already, and that's, well, one of the
longest times. Bye bye... echolocating... stretching the wing...
ALAN ALDA (Narration) On most nights, two or three of
Elizabeth's students are prowling through the forest, tracking
bats. Here's our round-eared bat. The slow beeps means it's
resting -- probably recovering from the stress of being handled.
Night after night, year after year, painstaking work like
this has built up a unique record of the bats on Barro Colorado.
But what are the bats actually doing out there, in the pitch
black of the forest? Here's one way to find out.
Is this good?
ALAN ALDA (Narration) Elisabeth calls this her
bat detector -- a high-tech box that transforms bat sounds,
which are normally too high for humans to hear.
ELISABETH KALKO Oh! And we have a bat already flying above us.
ALAN ALDA I didn't hear anything.
ALAN ALDA (Narration) The box
instantly lowers the pitch of the bat sound, so we can listen
ELISABETH KALKO These are the bats that live under the
roofs of the houses here.
ALAN ALDA Can you tell from that
sound what it's doing?
ELISABETH KALKO Yeah, right now --
beautiful, beautiful -- we hear a lot of different things
but it's very fast, unfortunately. What you hear now, these
are search calls. They are searching for insects, and when
you hear ddd... brrrrr, the brrrr is a terminal phase. This
is when they home in on insects.
ALAN ALDA That brrrr?
ELISABETH KALKO Right, that was a terminal phase again. And what I find
so fascinating about it is when you walk out here usually
or normally you wouldn't get any of the life above us, and
we wouldn't even know that bats are here, and now the forest
comes alive, the acoustic world comes alive, and there's a
lot of action going on!
ALAN ALDA What? What? You're hearing
something great - what?
ELISABETH KALKO Well, they're just
feeding like crazy right now. Hear all these weird buzzes?
ALAN ALDA Well you went into ecstasy with these sounds happening,
and I can't - that's my question - how many years did it take
before you could interpret these sounds so acutely? I mean,
you can tell everything they're doing! How long did it take
ELISABETH KALKO Well, I'm working with this system here,
with echolocation I think, well, let's see - it was almost
ALAN ALDA (Narration) We brought a special night
vision system out to the island, to help us see what Elisabeth
already sees in her mind. The night sky in the forest is filled
with action. The bats are hunting. All those clicks and squeaks
are different kinds of echolocating sounds, used to bounce
off, and find, the prey. It's mainly insect eaters that are
out right now.
ELISABETH KALKO Wha!
ALAN ALDA (Narration)
The zipping noise is the final burst of sound as the bat swoops
in for the kill.
ELISABETH KALKO That must have been an excellent
ALAN ALDA (Narration) Elizabeth's latest
work is figuring out exactly how bats use all these different
ELISABETH KALKO The white-lined bats, they're called
Saccopteryx bilineata, catching the insect about three meters
above the ground.
ALAN ALDA (Narration) So her nights are
spent out in the forest, making recordings for analysis later.
ELISABETH KALKO Searching for the insect...
ALAN ALDA (Narration)
Here's a typical hunting sequence.
ELISABETH KALKO Now...
Speeding up the calls... Right...
ALAN ALDA (Narration) And
then in for the kill.
ELISABETH KALKO A gorgeous terminal
ALAN ALDA (Narration) For Elisabeth, it's like some
kind of air show up there.
ELISABETH KALKO I hear the naked-backed
bat, then I hear Saccopteryx bilineata, the white-lined bat,
in the background I hear a free-tailed bat. So it's a whole
symphony of bat calls that surrounds us right now.
(Narration) The edge of the lake is a favorite hunting ground
for bats. Every night, insect eaters and the big fish eaters
swoop out of the forest in a spectacular aerial display.
ALAN ALDA Are the bigger ones one species, and the smaller ones
ELISABETH KALKO Yes, yes. The big one is the fishing
bat, Noctilio leporinus, and that's a bat that is specialized
in catching small fish and occasionally also insects from
the water surface, and the smaller one is Noctilio albiventris
and that's a purely insect eating bat and taking prey from
the water surface too. We are now connecting the synchronization
unit with my sound recording equipment, so that we can actually
later on release this whole system.
ALAN ALDA (Narration)
To understand exactly how different bats hunt, Elisabeth invented
this multi-flash picture system.
ELISABETH KALKO So let's
see whether the flashes are working. Uh huh. Ready, go.
ALAN ALDA (Narration) The bats' echolocation sounds are recorded
at the same time. Watch this bat delicately plucking fish
from the water surface.
ALAN ALDA Are they zeroing in on the
water and the prey at the same time, and each other, all those
ELISABETH KALKO Actually what they do is since they
echolocate individual targets, they know exactly which spot
they want to go to. For example, for the fishing bat when
a little fish breaks the water surface, the echolocation call
to the bat gives an echo back that indicate very clearly there's
a fish breaking the water surface, so the bat goes specifically
for this spot. There were almost 300 nights that I was out
there, listening to bats, making multi-flash recordings, and
trying to decipher a little bit of their mysterious lives.
ALAN ALDA (Narration) Elisabeth keeps an exhausting schedule
-- nights in the forest, then days in her lab.
Yes, I have a print here from one of the pictures that we
took last night, and it shows the bat approaching a little
fish that broke the water surface, and the bat approaches
this water disturbance and hits the water with its claws,
tries to get the fish out of the water, takes the fish out,
and then carries it away.
ALAN ALDA When the bat senses the
fish coming out of the water, by the time the bat gets there
the fish is back in the water.
ELISABETH KALKO Exactly.
ALAN ALDA So the bat has to know where it would be at the right
ELISABETH KALKO Right, and this is visible here, because
we see the disturbance here in the water, but when the bat
hits the water surface it's different.
ALAN ALDA (Narration)
In the split second the fish breaks the surface, the bat measures
its speed and direction, using a rapid burst of calls. Here
they're slowed down fifty times.
ALAN ALDA So how many of
these little beeps is the bat making in a second?
ELISABETH KALKO In the terminal phase, and this is when they make the
most calls, they may make about 150 to 170 calls per second.
So that's a lot.
ALAN ALDA It is! What kind of a mechanism
does the bat have to make such rapid sounds? How does it do
ELISABETH KALKO It does it, like we talk. Bats produce
their calls, with their vocal cords, and so it's like talking.
But of course they have special muscles that allow them to
get the tension up and to produce these calls at such a fast
ALAN ALDA (Narration) Now look at insect eaters. First
they use a special call which actually tells them what kind
of insect is out there. Then they track the insect -- it's
the lower set of dots in the picture -- with a different call,
until the moment they snatch it out of the air. So here's
the first call, used to identify the prey. It's a series of
steady notes that bounce off the insect's wings, and come
ELISABETH KALKO It gets modulations back that
tell the bat there is an insect. And not only that, it can
also determine the wing beat rate. It knows, this a beetle,
this a moth--it knows the direction the insect is flying.
ALAN ALDA It's a real sound picture of these wings beating.
ELISABETH KALKO That's a real sound picture. But the bat has
great difficulties with its call type to determine how far
away is the insect.
ALAN ALDA (Narration) Now the bat changes
to rapid calls, like the fish eater. Elisabeth discovered
that each of these is a falling call, like a series of piano
notes. They're a super-accurate way to measure the distance.
ALAN ALDA It's going "dddddddd", and from the other end of
the room it's coming back, "ddddddd", but it's measuring the
time of each of those notes as it comes back.
ALAN ALDA (Narration) Elizabeth's work is sorting out,
for the first time, just what it takes to be a bat. Sometimes
she'll keep some from the nets for a day or two, for detailed
study. Tonight she's looking at fruit bats, so she sets out
an irresistible bunch of wild forest figs. Figs are not known
as fast movers, so fruit bats don't need fancy calling systems
-- only a simple call to avoid obstacles in the forest. First
it flies a series of passes by the fruit.
Very good, very good, it's coming... very soon. Yes it's going
to do it...
ALAN ALDA (Narration) And then...
ALAN ALDA (Narration) Elisabeth has figured out how
it actually finds the fruit -- it's by smell. Elisabeth Kalko
has to be one of the world's most enthusiastic bat people.
Here on the island, she must be in paradise.
ALAN ALDA What
is there about this place that gave you the chance to learn
so much more about bats?
ELISABETH KALKO Just imagine in all
of the United States you may find about 44 species of bats.
Here, BCI, this little island, 15 square kilometers, we are
up to 71 species already, and all of Panama may hold 120 species
of bats. And that's even a lot when you look at the world
where there's about a thousand species, including flying foxes.
So Panama has basically more than a tenth of all bat species,
and that's quite astounding.
ALAN ALDA (Narration) So here are the ingredients for
this story... Willi, the Swiss chef...Antonio, the committed
environmentalist...A table full of rainforest produce, none
of which I can identify... And finally, a large forest rodent
which Willi seems to want to eat...And I don't think I really
ALAN ALDA Can I ask you a personal question? Do you eat
WILLI DIEGELMAN Yes. It's fantastic! I like it. Smells
ALAN ALDA Smells very good. Yeah.
ALAN ALDA (Narration)
While the soup simmers, we'll put our story's ingredients
together. The story begins in the first decade of this century.
The Panama Canal was being built, the world's largest construction
project at the time. Even though it involved earth moving
on an unprecedented scale, the clever design of the canal
reduced excavation to a minimum. Ships were to be lifted up
through locks to a new artificial lake, forming the central
twenty five miles of the canal. That way, massive excavation
at sea level, from ocean to ocean, was avoided. Gatun Lake
was created by damming a river which flowed out of Panama's
interior. Here's Barro Colorado Island becoming isolated as
the surrounding valleys flood. Here's one end of the lake
today, and here's the dam which caused it. It was a smart
design for the canal, but it has to have lots of fresh water
to keep it going. This is how it works:
ALAN ALDA These are
in place in kind of a v-shaped position. Is that for a reason?
EDGAR PAULK Yes, that's actually a concept originated by Leonardo
da Vinci. Centuries ago, he designed this type of gate. Water
pressure keeps them tightly closed.
ALAN ALDA The water pushing
this way keeps it closed?
EDGAR PAULK Exactly. With just a
small difference -- right now there's 54 feet here -- but
with just a couple of inches, it would be impossible to open
ALAN ALDA (Narration) Watch as this ship enters the
first lock from the Pacific Ocean. Fresh water has to be released
from the lock above, to raise the ship below.
ALAN ALDA That
water's beginning to bubble down there. What's happening?
EDGAR PAULK Right now they're transferring water from the
upper chamber. It's about 26 million gallons that enter into
this chamber by gravity, and it's all divided up through 100
holes in the bottom, so it comes out very quickly, but very
ALAN ALDA How quickly does 26 million gallons...
EDGAR PAULK Eight minutes.
ALAN ALDA Eight minutes?
EDGAR PAULK Yes. The tunnels are 18 feet in diameter.
Because I'm thinking how long it takes to fill a bathtub.
EDGAR PAULK A bathtub takes 9.
ALAN ALDA (Narration) So it
takes an awful lot of water for a ship to pass through the
ALAN ALDA Like how much does Panama City use
every day? GUIDE Panama uses probably for a whole day what
they use here for one ship.
ALAN ALDA (Narration) With the
water levels equalized, Leonardo da Vinci's lock gates are
free to swing open. These are the largest lock gates ever
built, by the way. Then our ship can be guided into the next
lock, for another step up. So feel like a quick cruise through
the canal? Let's go. Here we are in the Miraflores locks,
coming in from the Pacific. Up we go, 28 feet. Next lock --
another 28 feet. Then out across a small intermediate lake
to Pedro Miguel locks, the last step up. Into Pedro Miguel...
up 28 feet... and now we're in the six-mile Gaillard Cut.
This was where the bulk of the excavation had to take place.
At 85 feet above sea level, we're sailing across the continental
divide. Now we're crossing Gatun Lake... And at the end of
the lake, we're into Gatun Locks for our three steps back
down to sea level. And of course, flushed out into the Atlantic
Ocean with us are 26 million gallons of fresh water. No problem,
right? Well, actually there is a problem. In Panama, as in
many countries, poor farmers burn the forest vegetation to
clear fields. It's called slash-and-burn agriculture. Every
few years, when the soil's exhausted, they have to move on
to clear fresh areas, to grow crops, or graze cattle. Slash-and-burn
by a growing population is a big threat to the canal. A forest
stores rainfall like a sponge, but without forest the land
erodes rapidly. The canal and the lake could just clog up
with forest soil washing off the land. So far routine dredging
has kept things clear, but in the hills bordering the canal,
there's a radical alternative to slash-and-burn taking shape.
The process does start with some slashing -- attacking these
tall, tough stands of grass.
ALAN ALDA Where did this grass
come from? Why do you say it's invading, I mean, wasn't it
ANTONIO TELESCA Yeah - this is not native. This
comes from Asia, and when the grass comes into Panama, we
begin to have a problem. Because the grass is more aggressive
like any kind of grass we have in Panama, and it's growing
more fast than any kind of tree we have.
ALAN ALDA How fast
does this grass grow?
ANTONIO TELESCA Well, some of the investigation...
talking about 5 inches a day.
ALAN ALDA 5 inches a day?
ANTONIO TELESCA 5 inches a day.
ALAN ALDA In one day this grass grows
ANTONIO TELESCA Yes. In the beginning when you're
cutting the grass, if you let the grass keep growing again
-- 5 inch a day it's beginning to grow.
ALAN ALDA (Narration)
The fast-growing grass was brought in to control erosion while
the canal was under construction, but now it has spread all
over the canal zone. It's wasted, unproductive land.
ANTONIO TELESCA Buenos dias.
ALAN ALDA Buenos dias.
ALAN ALDA (Narration)
The goal is to restore forest on the grassland -- and this
is the second step. They're harvesting a kind of bean, planted
here a few months ago, after the alien grass was cut. The
beans grow even faster than the grass, and once there's shade
on the ground, the grass can't grow back.
Take a piece.
ALAN ALDA (Narration) The beans are a good crop
for a poor farmer, too.
ANTONIO TELESCA Open one, open one.
You can put this in rice and you can eat it. The taste is
ALAN ALDA (Narration) Now here's the best part. At the
same time they plant the beans, they also put in young trees
-- native, forest species that can handle some shade, and
including plenty of valuable fruit and nut trees for the farmers
to harvest later. With the grass held back by the beans, the
young forest gets its start in life.
ALAN ALDA So this plant
gets this tall in eight months. In eight months, how tall
would the grass get if there were no beans here?
If no beans? Maybe in eight months the grass is like 2 or
ALAN ALDA Like 6 feet maybe.
ANTONIO TELESCA Like
ALAN ALDA 6 to 9 feet!
ANTONIO TELESCA Like 6 to 9
ALAN ALDA So this plant would have no chance whatsoever!
ANTONIO TELESCA It's impossible because the grass is growing
like this, and there's no sun.
ALAN ALDA (Narration) Seven
years later the restored areas look like this. From useless
grassland to valuable new forest.
ALAN ALDA Was this all grass
ANTONIO TELESCA Yeah. Seven years ago, all this area
ALAN ALDA (Narration) And there's one more remarkable
aspect to the project. One of its biggest successes -- pacas.
ALAN ALDA Paca?
ANTONIO TELESCA Yup. Have you ever feed paca?
ALAN ALDA Have I ever what?
ANTONIO TELESCA You ever eat paca?
ALAN ALDA Eat? I've never seen it!
ANTONIO TELESCA You've
never seen it?
ALAN ALDA What a strange looking animal!
ANTONIO TELESCA You want to give him one of these?
ALAN ALDA Well,
let me see you feed him first. I want to see how...Yeah that's
what I thought. There's a great sense of sharing among the
ALAN ALDA (Narration) Pacas are nocturnal rainforest
animals, prized for their meat and hunted almost to extinction
in Panama. But Antonio's project is now giving them to farmers
to breed. Pacas eat rainforest produce, so they're another
part of a system which encourages poor farmers to use the
forest, not cut it down. Many of these ideas -- like domesticating
pacas -- were first developed at STRI to help prevent rainforest
destruction throughout the Americas. This is just a small
sampling of the hidden wealth of the rainforest. For example,
"picsbai". It's a kind of palm nut, that you roast.
ANTONIO TELESCA It's really good. And they
grow it in a pod...
ALAN ALDA It tastes so much like something
I know, but I don't-
WILLI DIEGELMAN A little bit like.....chestnuts.
ALAN ALDA Chestnuts - yeah!
ALAN ALDA What is that made of?
What are these things? This is in the pie?
ALAN ALDA Mispero?
WILLI DIEGELMAN Nnn... nispero
ALAN ALDA Nispero. What's that?
ANTONIO TELESCA It's a wild
ALAN ALDA A wild fruit. So this is a fruit pie.
ALAN ALDA (Narration) Cashews are a rainforest crop, but they can
yield more than nuts.
ANTONIO TELESCA This is the nut.
ALAN ALDA Oh! this the nut - okay, look! look! How many times we've
eaten cashews and we never knew how it looked on the tree!
ALAN ALDA Cashew juice. I have never had cashew juice before.
This is going to be great - let's see... It doesn't taste
like a cashew at all.... It's very good tasting juice. I mean,
I have to tell you, I have to get over the way some of it
looks. Like that fruit looks like it needs a shave over there!
This doesn't look too good, and then when you open it up,
it looks even worse! It's very interesting. It's got...The
flavor has twists and turns that I'm not used to in anything
else I've ever tasted. It looks like it comes from another
planet, and it tastes like it comes from another planet!
ALAN ALDA (Narration) And now the chef's specialty. Yes, it's paca.
ALAN ALDA Rat soup... mmm. Well, whenever I'm in the jungle
this is what I have. Mmm... whoa! You've got to try this!
This is great!
ALAN ALDA (Narration) Then, over the nispero
pie, it came to me -- a new business. Good for the forest,
ALAN ALDA You've got to go to New York, or Paris or Geneva
and open up a restaurant that just serves jungle foods. It
would be interesting for people to try all these tastes.
WILLI DIEGELMAN A jungle restaurant in New York. With a Swiss chef!
ALAN ALDA Now these are stingless bees, huh?
Yeah these are the user friendly bees.
ALAN ALDA (Narration)
David Roubik, STRI's resident bee expert, works with Panama's
ALAN ALDA How do they keep from getting eaten?
DAVID ROUBIK They have all the same problems that any other
bee that makes honey and has a big luscious nest to eat would
have, but they're very selective about where they build a
nest. It's usually only in a standing tree, and they do have
defenses. Some of them bite very well.
ALAN ALDA Oh, oh, oh.
DAVID ROUBIK So it's a combination. They're not fools, you
ALAN ALDA But we're surrounded by them here, so
we don't have to worry?
DAVID ROUBIK Yeah, well they're just
coming and going here. It's an active colony.
ALAN ALDA (Narration)
Actually inside his lab, David keeps an entire colony of one
of the many stingless bee species.
ALAN ALDA They make honey,
so what do they make it out of?
DAVID ROUBIK Well, out in
this forest there are about a thousand species of different
flowering plants they can go to, they might use two or three
hundred kinds during the course of a year. So constantly,
every day of the year, all during the daylight hours they're
foraging . Bees are going out, maybe as far as two or three
kilometers and bringing back food.
ALAN ALDA (Narration) The bees have to make hundreds of trips
each day, back and forth between forest and hive. What the
researchers have found is that the bees can tell each other
exactly where to go in the forest.
ALAN ALDA How accurately can the bee communicate to
the others where this good source of food is?
Finding how well they could communicate was really what shocked
us, because they're not just kind of giving a general cue
of "there's some good food out here, fly around and maybe
you'll find it". They're saying how far away, how high up
and in what direction, so three dimensions.
ALAN ALDA (Narration)
The story of this remarkable discovery begins with David's
specially arranged bee colony.
ALAN ALDA Where are they, here?
ALAN ALDA (Narration) A pipe running through the wall channels
the bees into an observation hive, where you can watch and
listen to the bees in action.
ALAN ALDA So this is what it
looks like inside a normal hive.
ALAN ALDA (Narration) These
are foragers entering and leaving the hive. Here on the left
is where other workers store honey. This is the queen, mother
of all worker bees, who lays her eggs in rows of cells. There's
also one other thing about these bees.
ALAN ALDA They have
little numbers on them.
DAVID ROUBIK This is a sign we've
been here before.
ALAN ALDA Just let me make a guess -- you
put them there, right?
DAVID ROUBIK You're exactly right.
ALAN ALDA (Narration) How on earth do you put a number on
JAMES NIEH How we do it is we just grab a bee. They're
quite docile when they're feeding, and also they're stingless
so that helps. Here I'll let you try and label it....
ALAN ALDA (Narration) Biologist
JAMES NIEH works with David on
bee communication research.
ALAN ALDA Now what do we do?
JAMES NIEH And then you smear a little bit on to her thorax.
ALAN ALDA Her thorax is right after her head, right?
Right. Exactly, that little furry spot.
ALAN ALDA (Narration)
Being able to tell one bee from another is crucial for doing
ALAN ALDA Seventy-eight. Now we've
numbered a bee! Number seventy-eight is my bee! When this
bee makes a great scientific discovery, and we all go to Sweden
to get the prize, number seventy-eight is mine!
(Narration) After the bees are numbered, they're trained.
Sugar water is injected into the hive to excite the bees interest.
Next, a feeder with the same sugar water is placed at the
hive entrance. In just a few seconds the bees discover the
feeder, and there's no doubt they like what's there. Once
a few bees have had a good drink, the feeder is moved away
from the hive. As long as it stays within smelling distance
of where it was before, the bees can easily find it again
after making deliveries to the hive. James steadily leads
the bees into the forest, advancing twenty feet at a time
-- about the maximum distance the bees can smell. So they
can train bees to forage anywhere in the forest... Even at
the top of a hundred-and-twenty-foot tower, which simulates
a tall flowering tree. You really have to love bees to make
this climb. The question they're asking here is whether bees
can communicate the height of a food source to their fellow
workers back in the hive. Of course some bees already know
where the food is, because they've been trained. That's why
you have to know their numbers, so they can be discounted.
Here's 3... 34... 5... 26. They're all trained bees. Wait
a minute -- here's one without a number. Well, that's a complication.
New workers are born every day, so there are always a few
like this. They have to be marked as they show up. Now as
the bees fly between the tower and the hive, James looks for
new recruits -- ones he hasn't trained to come here. Meanwhile,
down at the base of the tower David watches a second, identical
feeder. Maybe new recruits will find this one.
OK James, there you have it set up here now.
JAMES NIEH Let
me know if you get any new recruits, over.
DAVID ROUBIK No
recruits here yet, James, haven't seen a bee.
ALAN ALDA (Narration)
If the bees can communicate how high the food is, then no
new recruits should show up at the ground level feeder. They
should all head out of the hive, straight to the top of the
tower. And that, in fact, is what happens. These are all new
JAMES NIEH Looks like I just got my ninth recruit,
and that means about nine to zero, is that correct? Do you
have any new recruits down there? Over.
DAVID ROUBIK They're
making a bee line to you it seems to me. It's been pretty
dull down here.
ALAN ALDA (Narration) When the experiment
is reversed, and the bees are trained to the base of the tower,
all new recruits show up there. So the bees do somehow communicate
height. Next, bees are trained to a feeder north of the hive,
and the new recruits show up there -- not at a feeder to the
south. So the bees can also communicate direction. And it's
the same for distance. Even when two feeders are set up only
about thirty feet apart, new recruits always went to the feeder
where their hive mates were trained. So how do the bees do
it? Maybe the new recruits simply follow the trained bees.
So James repeated the experiments, this time capturing all
bees leaving the hive, and keeping those which had been to
the feeder. But new recruits still found the correct place,
so simple following can't be the explanation. Is it possible
the recruits follow some kind of scent trail in the forest?
After all, biologists know that bees often deposit a mysterious
liquid on leaves. To rule out this possibility, feeders were
taken across a lagoon where no scent trail could be left --
and the recruits still went to the right feeder. So looking
for some form of communication, James began videotaping bees
as they returned from feeders... And he found the secret world
of bee talk. This red marked bee has just returned from a
feeder. As it hands over food to other workers, it makes a
series of pulsing buzzes. Then it does a brief dance, accompanied
by another series of buzzes. By comparing bees that came in
from different feeders, James managed to decipher the buzzing
JAMES NIEH This is a bee that's foraging at the base
of the canopy tower. We also have another group of bees that's
foraging at the top of the canopy. And what you should notice
here, is that...
ALAN ALDA The pulses are shorter.
Exactly. Right. So from here to here the bee's unloading food,
and if you compare the pulses, they're definitely shorter.
ALAN ALDA (Narration) Short buzzes made while unloading food
mean that the food comes from near the ground. And the longer
the pulses, the higher the food source. For sound made during
the dance, the longer the buzz, the farther away the food.
ALAN ALDA It's like the bee book! It's like if they weren't
at home you could leave this around, they could walk across
it and read it and see how far to go.
JAMES NIEH Exactly.
It's a bee sentence.
ALAN ALDA It's a bee sentence.
(Narration) As for how the bees communicate direction, that's
still a mystery. Maybe number seventy eight will show them
how it's done.
ALAN ALDA (Narration) This is STRI's solution to one of the
biggest obstacles that forest researcher's face.
RESEARCHER Arriba. Rapido.
ALAN ALDA (Narration) It's one of those simple ideas that
seems so obvious once someone has thought of it. It's a construction
crane that gently flies researchers around the normally inaccessible
tree tops. Until they built the crane, nobody had really had
a good look around up here. In tropical forests the sun-drenched
canopy is where the action is. It's where well-known big guys
like monkeys or iguanas live. But it has also turned out to
be home to an astonishing variety of small things -- to a
degree that has just stunned the biological world. Hector
Barrios and his team return to the same trees week after week
to collect insects. From its fixed base, the crane can reach
about 200 trees. There are specialized traps for flying insects.
Here's a sampling of the results -- literally thousands of
kinds of beetle, found on just two tree types. After these
revelations, scientists are now convinced there may be thirty
million species of life on the planet, most of them tropical
insects. Nobody quite knows why tropical forests have so many
insects, or for that matter why these particular insects can
manage to consume so much of the forest without damaging it.
They're leaf cutter ants. Everywhere you look in the forest
you'll find their trails. The ants haul enormous leaf chunks
along trails up to a quarter mile long. The leaves usually
come from way up in the canopy, from trees that have just
sprouted a fresh crop of foliage. The new foliage is tender
-- easier to chomp into pieces. Then comes the long march
home. The most amazing thing about these ants is they don't
actually eat the leaves, once they're back in their underground
nests. This is what a leaf cutter nest looks like. It's not
a pile of leaves, but a mass of spongy fungus which grows
on the leaves, consuming them in the process.
ALAN ALDA Can I just
feel that? It' s sort of moist, and soft, mushy.
And that's all like plant parts that have been invaded by
ALAN ALDA Now, do they eat that fungus? That's
ULRICH MUELLER The fungus produces particular
structures which are rich in portion and sugars.
(Narration) The ants only eat the nutritious products of the
fungus -- and that's all they eat. They have to grow their
fungus to survive.
ALAN ALDA This is a really a farm, isn't
it? This is real farming.
ULRICH MUELLER Yeah, that is the
closest in the animal kingdom of what humans would be calling
agriculture. It's not true agriculture, it's fungiculture.
But it has the same kind of features of our agricultural systems.
ALAN ALDA So humans developed farming, about when?
ULRICH MUELLER As far as we know the first signs of agriculture date
back about ten thousand years ago.
ALAN ALDA And ants figured
it out, about when?
ULRICH MUELLER About fifty to sixty million
ALAN ALDA Ten thousand years verses fifty or sixty
ALAN ALDA (Narration) Not only were leaf cutters
way ahead of us as farmers, they also invented the world's
first professional classes... Like garbage collectors. Here
they're throwing out dead fungus, that no longer produces
ant food. Within a mature ant colony of maybe twenty million
members, perhaps a million will be specialized garbage handlers.
And the garbage dumps can get enormous. Then there are the
security forces. This little fly, on the right, attacks worker
ants. So all along the trails you'll see special guard ants
riding shotgun on the leaf cargo. And there are always openings
in the highway maintenance department. If a leaf blocks the
trail, special road crews quickly maneuver it aside, so traffic
can get moving again. STRI biologists have been figuring out
how much foliage the highly-organized leaf cutters consume
each year. First they count ants on the trail... Then they
collect sample cargoes to work out the average ant leaf load.
It seems that ants cut down as much as twenty percent of the
forest's foliage each year. This result really has people
puzzled -- how does the forest handle that kind of impact?
As for the ants -- well, they must keep pretty busy.
ULRICH MUELLER I don't think there's any time for them to develop
anything like watching TV or playing golf.
ALAN ALDA Well
you don't see any little... most of the antennas are attached
to the ants themselves. Very few on the TV sets.
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BRIDGE THAT CHANGED THE WORLD
ALAN ALDA (Narration) This is the Isthmus of Panama, as seen
today by a satellite's camera. It's a delicate land bridge,
connecting North and South America. But for most of the earth's
history, if satellites had been around they would have seen
something like this -- open ocean between the two continents.
A direct connection between the Atlantic and Pacific. Panama's
sleepy Caribbean coast, on the Atlantic side, bears traces
of the Isthmus' violent origins. Our guide is Tony Coates,
STRI's deputy director. He's a geologist by trade, who has
spent the last five years searching the coast for rocks that
tell the story.
TONY COATES Let's talk a little bit about
what we're going to do today. You've got the Cusapin map?
TONY COATES We'll go down to Tabobe, here,
and then if we've got enough time we'll come on down to Nancy
ALAN ALDA (Narration) For
Tony, what's special about this remote coast is that its rocks
were formed deep in the ocean. Forces in the earth's crust
have since pushed them up to the surface, where geologists
can get at them. Here's our first stop. The rock here was
formed by layers of mud which piled up on the ocean floor
about twenty million years ago. As you'd expect, the mud layers
trapped within them traces of ocean life from that time. And
for Tony, the life forms carry a simple, dramatic message.
TONY COATES These rocks tell you that 20 million years ago,
there was no Isthmus of Panama. There was only an ocean --
a deep ocean, more than six thousand feet deep -- and we know
that because these rocks are filled with trillions of microscopic
organisms that only live in the mud at the bottom of such
ALAN ALDA (Narration) When you wash off the ancient
ocean mud, and sort through the remains, you find countless
tiny fossil shells. Today we only find these creatures living
at ocean depths of a mile or more. So twenty million years
ago -- no Isthmus. Tony reads in rocks like this what happened
TONY COATES The Isthmus began when the volcanoes erupted
on the floor of the ocean, and this is a perfect example of
the lavas that would have come out of those volcanoes. The
moment is perfectly demonstrated in this little section over
here. Here we have the deep ocean sediments that we saw before,
and you can see along this line they are overlain by the jagged
boulders of lava that you were just looking at. This is the
moment in time when the Isthmus began to form.
ALAN ALDA (Narration)
About eighteen million years ago, the ocean between North
and South America was a very violent place. Lava spewing out
from the underwater volcanoes steadily built up from the ocean
floor. A chain of volcanic islands began to form, linking
the continents. And after a few million years, a solid land
bridge was established. Just up the coast, Tony finds evidence
of the final, placid stage of the creation of the land bridge
-- the remains of an ancient beach, that formed on the slopes
of an extinct volcano. It's complete with fossilized seashells.
Tony has figured out that the land bridge was continuous by
about four million years ago, setting the stage for violent
upheavals, in turn, in the animal world
ALAN ALDA What did
that do to the evolution of the animals in the water, and
the plants and so on?
TONY COATES Obviously there's the dramatic
connection of the two continents in this incredible ecological
confrontation that took place -- predatory birds 12 feet high,
that could have ripped your and my head off, came north as
far as Florida and Texas. 18 foot high sloths could browse
ALAN ALDA They still have them in Hollywood.
TONY COATES They didn't fair well when they went north. Today
we only have three species in America that derive from South
America -- the hedgehog, the opossum, and the armadillo. By
contrast, vast numbers of species have evolved from the animals
that went south. So that South America today is about 60 percent
made up of animals derived from the north in that great ecological
ALAN ALDA (Narration) The isthmus joined two
continents, but it separated two oceans. In the process the
warm, sheltered Caribbean Sea came into being. Coral reefs
now grow here -- but not on the colder and rougher Pacific
NANCY KNOWLTON Xavier, did you find anything?
XAVIER Si, venga a ver.
ALAN ALDA (Narration) On this beach on the
Pacific side, STRI's
NANCY KNOWLTON is looking for snapping
shrimp. They've been around here for a while -- in fact, since
before the oceans were separated. So now there are shrimp
cousins on each side of the Isthmus who haven't seen each
other for a few million years. What happens when there's a
family reunion? As you might expect, things don't go so well.
A fight breaks out almost immediately between this Pacific-side
male and an Atlantic-side female. Here's a pair from one side
only. This friendly behavior is how things ought to go. In
fact, Atlantic-Pacific pairs don't get along, and could never
reproduce. They've evolved into separate species. Dozens of
species are now split between the two sides, evolving separately.
So the Isthmus had an impact on life in the ocean... It transformed
life on land, in North and South America...And it even made
itself felt half a world away. What happened is this. Before
the Isthmus formed, the tropical waters of the Caribbean flowed
into the Pacific Ocean. But once the way was blocked, this
flow was diverted north -- forming the Gulf Stream. This immense
conveyor belt of water warmed up Europe... And at the same
time transformed Africa. Lush, tropical forest turned to drier,
savanna grassland. Many scientists think it was this change
that prompted our ancestors to begin to walk upright -- on
their way to becoming human.
ALAN ALDA If you look at a map
of the globe, the Isthmus of Panama is a relatively small
part of it. It's a pretty minor dot on the globe.
A sliver, a tiny sliver.
ALAN ALDA And yet once that formed,
there were these vast changes in life on the planet that you're
describing, all over the planet.
TONY COATES It triggered
what I think is probably the most dramatic event that's happened
on earth since the extinction of the dinosaurs.
(Narration) So from its ancient effects on climate and nature,
to today's priceless knowledge that scientists are extracting
from the forest, Panama continues to profoundly affect our
world. As we said at the beginning -- quite a record for a
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