Ultimate Swarms Page #2

---

on the receiving end

of a sneaky

head-butt, a signal to stop dancing.

So it's actually a combination

of enthusiasm and bullying

that helps the bees agree

and prevents a decision deadlock.

So what does this swarm

make of the three hives?

Jeez! They're everywhere.

Well, those 40,000 bees have now

taken to the air,

absolutely full of...the noise

is incredible

and they're all heading to that

hive over there

and so far, not one sting.

Ooh! Ow!

Something just got me!

Sorry, correction - one sting!

And while two of the hives

are still empty,

hive C is proving popular and

the bees are moving in en masse.

They've made the decision

collectively

and they've picked this hive. This

was the one I thought they'd pick.

It's absolutely right,

is the right size.

It's the perfect angle,

the perfect everything.

And it's their group

intelligence,

the ability to use the power

of the swarm to make the right

decision that makes honeybees

the ultimate team...

Because it's a fact that hundreds

of individuals

make a better decision together

than a single expert.

And that's something both animal

swarms and humans have in common.

It's a bizarre phenomenon first

noticed back in 1906

at a county show much like this one.

Ha ha!

Scientists were amazed by what

happens during a simple competition

asking people to guess the weight

of a cow.

When they analysed the results,

not only was the average

of everyone's guesses more accurate

than the winning guess,

it was also a much better guess than

that of the experts who took part.

So today, we're going to put

it to the test

with the help of Zinny here.

We asked a selection of people

at the Royal Bath Show

to guess Zinny's weight.

How accurate will they be as a group

and can they beat one of the pros?

Right, well, the results are in

and all I've got to do now is to add

up all the estimates

from the crowd, get a total,

divide that by the number of people

who guessed...

The answer we get is 588 kilograms.

Now, a livestock expert guessed 584,

so they're very close.

But who's closest?

It's time for the cow to reveal all.

Haven't got her back legs in yet!

Haven't got her back legs in.

595 kilograms. Incredible!

That's just seven kilograms higher

than the group's estimate.

The crowd got it just about spot-on,

and they beat the experts.

It seems many brains

really are better than one,

and that's due to something

known as The Wisdom of the Crowd.

Our highest guess was 1,400 kg,

and our lowest 200 kg.

So, both way off,

but when a crowd works together

the odd crazy guess

doesn't really matter.

And that works for nature, too.

One animal might make a bad

decision,

but unless others have the same

reaction, the swarm isn't fooled.

That's why taking the option to ask

the audience in a game show

is such a smart move.

They get it right about 90%

of the time,

compared with a 65% success rate

from the experts.

It's no wonder swarming has helped

some creatures become

the ultimate decision-makers.

But not all swarms

are about boosting brainpower.

Some are about working together

to solve a problem.

The next stop on my journey

is Christmas Islands,

a tiny volcanic outcrop

in the Indian Ocean.

This dramatic, otherworldly

landscape

is the setting for an extraordinary

swarm on the move.

And right now is the best time

to see it in action.

Oh, my God, that is so...

The island is about to go

into lockdown.

Every year as the monsoon rains

arrive,

60 million red crabs emerge

out of the trees.

A swarm facing the ultimate

challenge.

These land crabs live in a forest.

But like their coastal ancestors,

they're still completely dependent

on the sea to breed.

And between the forest

and the beach

lies a gruelling six-mile treck.

This one is a female.

You can see underneath...

Gosh, she's really skittish.

If I hold her very carefully

you can see underneath

that brown mass at the end of her

abdomen under her tail,

is something like 100,000 eggs.

The reason that the females are

a little more difficult to handle,

they're much more flighty,

is because all they've got

on their mind just now

is to get these eggs...

Ow! ..into the sea as fast

as they can.

So that's what she has to do now,

so I'm just going to let her...

Oh, if I can get...

..get on her way.

She knows exactly which way to go.

The Christmas Islands crabs follow

the same well-trodden route

for generations.

But the arrival of humans

on the island

has given them a few extra obstacles

to deal with.

But nothing can get in the way

of their epic journey.

In just over a week, the crabs

will cover up to six miles.

For a creature of this size that

spends most of its life underground,

that's like running several

back-to-back marathons

with no training.

So how do they do it?

Scientists have recently discovered

it's all thanks

to a special internal sugar reserve.

Powered by a massive sugar rush

once a year,

these laidback forest creatures

suddenly turn into long-distance

athletes.

Oh, my goodness! Look at this!

This is...

This is unbelievable.

There's just crabs as far

as the eye can see.

Every inch of this rock is covered.

Amazingly, after days of walking

and dodging obstacles,

tens of millions of crabs have

survived and made it to the beach.

Just in time for their next big

challenge.

Tonight's the night.

They've got to shed their eggs

on a pre-dawn high tide,

when the difference between high

and low tide is at the smallest,

because if they fall in the sea,

they drown, unbelievably.

Being land crabs,

they can't survive in the sea.

But they've got to get their eggs

in the sea.

They all have just one tiny

window of opportunity.

And according to my calculations,

that should be in about

six hours' time.

So, I'm taking my place with

the crabs and waiting for high tide.

It's 3am, and all around me

female crabs have just started

frantically scrambling

to the edge of the surf.

Well, this is it.

The annual mass spawning

has started,

and it is just one of the most

incredible things I've ever seen.

It's easy to forget how treacherous

this moment is for the crabs.

Many of them will get

washed away and drowned.

But it's a risk they have to take.

The crabs are actually spawning

all around me.

Every time they spawn, they put

their claws up

and they shake themselves,

and as they do that

they shed 100,000 eggs each.

So many trillions of eggs have been

shed into the Indian Ocean

that it's turned into soup.

That is just full of now

freshly-hatched crab eggs.

The minute they hit the seawater,

the eggs hatch into tiny larvae.

But now they're at the mercy

of tides and currents.

Most will end up as fish food or get

swept away into deeper waters,

never to be seen again.

Which is why this swarm is so vital.

To ensure the survival of just

a few crabs,

nature has to throw

a lot of zeros at the problem.

Over the next three days,

Rate this script:0.0 / 0 votes