Episode 2 Nature's Weirdest Events

We live in a very weird world.

And the more we discover about our planet, the stranger it gets.

Every day, new stories reach us, stories that surprise us...

What is that?

-..shock us...

-Whoa!

PEOPLE TALK OVER EACH OTHER

..sometimes even scare us.

-Agh!

-Oh, my God!

We've scoured the globe to bring you the most curious creatures,

the most extraordinary people...

I can stick almost anything to my skin without no glue.

..and the most bizarre behaviour.

Using eyewitness accounts and expert opinion to explore a weird world...

..of unexplained underwater blobs,

flying goats,

and glow in the dark fish.

We examine the evidence, test the theories,

to work out what on earth is going on.

In this episode, we'll discover why goats might fly,

encounter some ghostly figures in the clouds

and find out why albatross chicks are being planted in flowerpots.

But first, let's meet some of the world's weirdest weaponized wonders.

Bondi Beach, Australia.

People come here to surf, to sunbathe and to be seen.

But in April 2015

this seaside sanctuary was to become the scene of a coastal crisis.

So I ended up having trouble breathing

and I started to get chest pains.

I've never felt anything like that before.

Surf life-saver Rosie Tailano

was taking part in the weekly biathlon.

I did my first leg of the swim

and all was normal, all was perfectly fine.

But as she raced towards the finish line,

something was waiting beneath the waves.

I felt an initial sting on my chest,

but I went to get it out of my costume and nothing was there.

It was very frightening.

But despite the excruciating pain, she struggled on.

So, it wasn't until I got home that the symptoms began worsening

and I began to get chest pain, the rash began developing,

and I had trouble breathing.

In minutes, Rosie was gasping for air.

She was rushed to hospital.

Thankfully, the doctors stabilised her condition.

But what had stung her?

What was this aquatic assailant?

Well, in Australian waters, there's no shortage of potential culprits.

On the sea floor, anemones and sea urchins cling to rocks,

some armed with a paralysing neurotoxin.

Hiding in the sands lurks the world's most dangerous fish,

the stonefish,

spines laden with a potent mix of toxins

that could kill a human within an hour.

Scuttling along the sea floor, the blue-ringed octopus

is one of the most dangerous animals in the ocean,

its venom over 1000 times more deadly than cyanide.

And sea snakes regularly come to the water's surface,

the scene of this crime.

But could their fangs really have punctured through Rosie's costume?

Well, Rosie had a theory of her own.

Originally, I thought it was just a bluebottle,

but there were no warnings that day of any stingers in the ocean.

These infamous jellies,

the Portuguese Man o' War, or bluebottles,

as they're known in Australia, can float in shoals of up to 1,000,

causing carnage when they come close to the shore.

Responsible for more recorded stings than any other species,

they inflict painful streaks when their tentacles,

sometimes up to 50 metres long,

wrap themselves around unsuspecting swimmers.

But for Rosie, the evidence just didn't stack up.

With a bluebottle sting,

the rash usually is a welt size with white appearance,

but with this, it was a very dotty, red rash,

quite different from the bluebottle.

So, with all the usual suspects ruled out,

the source of Rosie's sting was still a mystery,

but what could've caused her quite so much agony?

Well, at about the same time...

..some very strange videos started turning up on the internet.

Yes, just two months earlier,

this bizarre creature was washed up on the beach

just a few hundred kilometres to the north.

And this one had been found near Brisbane.

Millions of people watched these videos online,

all asking the same question,

what on earth are they?

These animals are so weird

that people didn't really know what to make out of them.

They are so weird-looking

and they almost look like they are alien organisms.

Somebody proposed that they were insects,

somebody else proposed that they were juvenile sharks,

and it wasn't until much more recently

people realised that they were molluscs and they were sea slugs.

Yes, these tiny animals are blue sea dragons,

a kind of nudibranch, or sea slug.

They come from a truly bizarre family

of brightly-coloured marine gastropods.

Most of them live on the bottom of the ocean,

grazing on anything, from corals to anemones and even other sea slugs.

But the Blue Sea Dragon dines on something entirely different.

Blue Sea Dragons feed primarily on the Portuguese Man o' War,

which is one of the most venomous organisms in the water.

What they can do is they can steal

that defensive mechanism that the Man o' War has

and utilise them for their own defence.

The Blue Sea Dragon lives at the ocean's surface,

which puts it at the scene of the crime

and it has the right weapon, too.

You see, it does something few other animals would dare,

it eats its fill

of the fearsome Man o' War,

but instead of getting stung,

it does something incredible.

It absorbs the paralysing

stinging cells, the nematocyst,

and concentrates the toxin.

Then it uses it for its own defences,

making it a very dangerous delicacy for any predator.

Or, of course, anyone who gets in the way.

WOMAN SCREAMS

When people encounter Blue Sea Dragons,

they're going to be finding them on the beach, typically.

By then, the animals are probably no longer venomous.

Now, if people were to encounter blue sea dragons in the open ocean,

that would be a different story, because that's where the animals

are basically charged and I would be very careful not to touch them.

To activate its deadly defence,

the blue sea dragon squeezes its muscles,

pushing out the stolen stinging cells, which detonate,

shocking a predator, or an unsuspecting swimmer.

Yeah, I was actually really surprised

that something so small and beautiful could cause so much pain.

So, the ingenious blue sea dragon doesn't produce its own venom.

Just like any good comic book villain, it steals it.

And then of course, it was simply a case of wrong place,

wrong time for Rosie.

Mystery solved.

But there's some news, too.

After just a couple of days,

she was fully recovered and back in the water.

Now, from one excruciating event to another,

with an even more unusual origin.

Papua New Guinea,

vast swathes of virgin rainforest unexplored by Western science,

where hundreds of weird and wonderful new species

are discovered every year.

But back in the summer of 1989,

nothing could have prepared a young ornithology student

for what he was about to find.

BIRDS TWEET

On my first trip to New Guinea, I was a student,

studying Raggiana birds of paradise and these birds have this amazing

behaviour where all the males get at the top of a tree,

they do this special dance, just to impress the female.

But little did he know,

he was about to discover something quite extraordinary.

We had about 40 mist nets up in the forest.

You catch a lot of other birds.

As you're taking them out of the net, they can easily scratch your hands.

And so after I let them go,

I had all these scratches on my hands, and I...

just licked my cuts and ran to the next net.

What happened next was truly... well, shocking.

BUZZING SOUND

My mouth began to sort of tingle and burn

and I would kind of describe the sensation as similar

to putting your tongue on a 9V battery.

So, what on earth had caused Jack such pain?

I didn't know what I had brushed up against,

there are lots of poisonous plants and other things.

You've got mosquito repellent all over your hands,

so any number of things could've caused this.

After a few days, Jack just forgot about it all,

that was until another researcher reported the same symptoms.

GRUNTING AND HUMMING SOUND

And I thought about it

and the only thing that my story and his story had in common

was the these black and rufus brown birds,

about the size of a jay, with a very sharp bill and very sharp claws.

So, what was this mystery bird?

Jack suddenly found himself fascinated, not by these...

..but by these, instead.

The Pitohui, a relatively drab and boring bird that for years had been

ignored in favour of its more glitzy cousins.

But could the plain old Pitohui be harbouring a secret?

Could Jack have discovered the world's first poisonous bird?

So we went back the next year and the first Pitohui that we caught,

I said, "Oh, yeah, I'm going to do this test."

And so I plucked a feather and popped it on my tongue and my mouth

began to tingle and burn and I was like,

"Wow, it's the bird that's doing this."

Now, you may think that sucking feathers is pretty unscientific.

But then, if you're in the middle of a jungle,

desperate to prove your bizarre theory, pretty much anything goes.

And I always like to think that a good biologist doesn't pay that much

attention to health and safety.

To prove the Pitohui was poisonous, Jack needed evidence.

As soon as you realise a bird is poisonous,

the first question you want to ask is, what is the toxin?

What is the chemical that makes them poisonous?

Jack brought back specimens to his lab for testing and the results were

truly bizarre.

You see, these birds weren't just carrying an annoying irritant or a

mildly potent poison, this was something off the charts.

It's a steroidal alkaloid neuro-toxin that targets the

sodium channels in our nerve and muscle membranes

and shuts them off.

In higher doses, it can actually cause paralysis and convulsions

and it can stop your heart and kill you.

It turns out that gram for gram,

it's one of the most toxic natural substances known,

more toxic than curare or strychnine.

So, just how had this bird become poisonous?

Well, there are plenty of other poisonous creatures out there but

only one of them was known to contain the same batrachotoxin,

the poison dart frog, found more than 15,000km away in Colombia,

where its secretions are used to paralyse and kill in seconds.

So, how exactly does a bird in Papua New Guinea come to be carrying

the same poison as a frog in Colombia?

Jack suspected it came from their diet.

We didn't know how the birds were actually getting the toxin.

And it's a really hard thing to figure out

because they feed on lots of small fruits and berries,

they feed on a huge variety of insects,

they also feed on small vertebrates like frogs and lizards.

So any number of these things could have provided them with the toxin.

For two long years, Jack's research seemed to have hit a dead end,

until help came from a very unlikely source.

So, the real breakthrough came when we went back to a little village

called Heroana and our host said,

"Oh, it's so exciting to see you guys because while you were away,

"we figured out where the Pitohui gets its toxin."

And he'd actually made a collection of about 44 beetles and each one was

meticulously labelled with the collector's name,

the locality and the date.

And this wasn't something we had asked him to do.

It was something that he had watched us and how we take data and he said,

"This is what they're going to want to know."

We were able to send some of them back to the National institutes of

health and they verified that, yes,

these things were full of batrachotoxins.

Each beetle contains only a low-level dose but just like the

dart frog, the Pitohui bio accumulates its poison

from its diet.

But why do they need such a serious self-defence?

Of course, the jungles are a dangerous place and the poison not

only protects the Pitohui from hawks, eagles and numerous

kinds of snake, it also acts as a natural insect repellent,

warding off avian malaria and the benefits don't stop there.

The Pitohui is so poisonous, its potent powers rub off

on its young too.

Quite literally.

Just holding the bird in your hand,

you get enough toxin on your fingers that if you rub your eyes or your

mouth, it'll cause tingling and burning.

So we expect that when a parent sits on a nest, that it

probably imparts enough toxin to the nest and the eggs or the young

nestlings that if a snake came up and tongue flicked it,

or even ate one of the babies, it would probably have a bad enough

experience that it would leave the other baby alone.

So, what about that? A bird with a toxic talent in self-defence.

But since Jack's first discovery,

they have identified even more species of poisonous bird.

But, whatever, the Pitohui will always be the first.

From discovering one of nature's secret forms of self-defence,

let's move on to harnessing one that's been known for millennia.

Kenya.

Vast grasslands filled with beautiful wildlife.

But here, on the fringes of Tsavo National Park,

it's not all a peaceful coexistence.

They destroy vegetables, houses, water pipes...

..throw stones, sharp objects, spears, arrows, occasionally guns.

They set their dogs on them.

But these aren't rival villages clashing.

This is something on a different scale entirely.

We've had people in our community with the roofs of their house ripped

off while they're sleeping inside.

It's a battle over territory.

As population growth pushes people ever deeper into the Savanna,

farms are becoming battlegrounds.

And in May 2008, one raid in Laikipia was devastating.

Elephant came and it had destroyed the whole thing.

-My God! There were 14.

-14 elephants.

So they're just coming...

They come overnight. Overnight.

Yes, this is man versus elephant and it's turning nasty.

When they're in conflict situations,

they can team up and this is incredibly intimidating.

They'll come in and they'll be very tightly walking together.

Any reaction at all and they'll all put their heads up, ears out.

There's a lot of aggression.

So this is incredibly intimidating for a farmer living in a simple mud

hut that even you and I could push down with our hands.

For the farmers, the stakes couldn't be higher.

So if they lose their crop, they have serious stress.

What are they going to feed their kids?

How are they going to pay the school fees?

How are they going to maintain their farm for the next season?

So this is a big challenge for them.

The problem is, the world's largest land mammal isn't just big,

it's smart, too.

It's very difficult to find a solution which elephants

don't habituate to.

Because even an electric fence, if they can work out how to push

their foot against it and push it over, they can get through.

The farmers' old methods, well, they just weren't working.

They needed a weapon,

something that the elephants were absolutely terrified of.

What about this?

I mean, everyone knows that elephants are scared of mice,

but it isn't actually the mouse itself that frightens the elephant.

All that comes from a legend that dates back to Roman times

when Pliny the Elder first described elephants as being scared of mice.

And it is a great story.

Popular cultures have reinforced it ever since.

But the evidence is questionable.

True, elephants do show fear when they see a mouse,

but this has more to do with the element of surprise than fear of the

mouse itself.

Any other animal scuttling around at its feet would cause the same reaction.

And, of course, there's another far more practical reason why employing

mice to protect the villagers' farms just wouldn't work.

You'd need thousands of mice to scare the elephants and then the

mice, in turn, would munch their way through the crops

you were trying to protect.

Lucy knew the villagers needed an ally,

but who or what could scare a whole herd of elephants?

Well, to come up with an answer, she had to think smaller.

Much smaller.

Amazingly, when we started talking to the local farmers,

these stories all started to come out.

We had farmers saying, "Oh, yes, of course, elephants won't touch

"that tree with the beehive in."

"Yes, I saw a hive being disturbed by an elephant and it chased the

"elephants away."

"Yes, I've seen an elephant with stings around the eyes."

A six tonne elephant with a hide that's over two centimetres thick,

scared of a bee that weighs just a tenth of a gram?

Surely not. This was a legend that Lucy needed to see to believe.

So, we came up with this idea of taking the sound of bees when

they've been really disturbed and playing that bee sound

back to elephants.

And as they responded, we saw these incredible behaviours.

They started headshaking and dusting, fanning their ears and they

would pick up their tails and run from the sound.

So, the legend was true.

But how could Lucy harness the power of this unlikely ally?

Well, by placing hives around the perimeter of the farms,

she could create a beehive defence system.

And by linking each small hive with a wire,

any elephant trying to cross the boundary line would cause the fence

to swing and the angry bees to swarm.

Genius.

Bees can sting around the eyes and the trunk, up the mouth,

and as we know now, African bees, they sting once and they release

this pheromone that triggers the other bees to come and attack,

so I don't think they're scared of one bee,

I think they're scared of a whole colony coming to get them.

And with temperatures rarely dropping below 15 degrees,

even at night, the bees can continue to fly,

providing 24 hour protection.

Lucy's insect army have stopped over 80% of the elephant raiders

in their tracks. What a success.

We found out that our farmers actually have a better improved life

through having these beehive fences because they can sleep more

at night-time, which means they can work more in the daytime,

which means they're putting more effort into their farms.

So now we've got a queue of people wanting beehive fences.

And there've been some unexpected benefits too.

It's not just the stopping of the elephants, but it's the honey,

the pollination services and it's that sense of ownership by the

farmer that they're doing something for themselves now,

to try to reduce human-elephant conflict.

So, there you go, an age-old legend inspires a modern-day solution.

What a story. Let's just hope that all of the elephants, the villagers,

and their army of bees all live happily ever after.

From the beautiful blue sea dragon to the world's first poisonous bird,

unexpected encounters can have painful results,

but if you can find a way to harness their power, well,

you could make yourself a very unusual ally.

Coming up, saving species takes a turn for the weird.

From a bizarre beaver delivery method...

..to an albatross living on the brink of disaster.

But for our first stop, we're winging our way to the USA.

The Rocky Mountains, Utah, home to a unique species, Oreamnos americanus,

the American Mountain goat.

One of the world's best climbers.

Known for their abilities to scale incredible peaks and pick their way

along dangerous precipices.

But in 2015, these adrenaline junkies took their extreme lifestyle

one step further.

Yes, they're flying, but why?

Well, in Willard Peak, the population has grown out of control

and is overgrazing this fragile habitat.

So, in Utah, we don't really have any natural predators for

mountain goats.

If the number of mountain goats gets too high in Willard Peak,

we could start seeing them causing damage to the surrounding vegetation.

So, we're trying to be proactive by taking goats off of there before

they get too numerous and too dense.

Kent needed to find a way to bring the numbers down and

with populations struggling in other areas, relocating them

was the perfect solution.

But first, he had to catch them.

Something that's easier said than done.

Mountain goats are 130kg of pure muscle.

And they're not just powerful, they're nimble too.

Able to jump over 3.5m in a single bound.

So, Kent's solution?

A crack team of relocation experts.

An aerial A Team, armed with high-powered pneumatic net guns.

But even with these hi-tech solutions, success isn't guaranteed.

So, mountain goats live in very steep, cliffy areas and so it's very

difficult to catch them because if you were to shoot a net on them

in the middle of a cliff, they would likely tumble down

and likely injure themselves or possibly be killed.

And so it's very important to make sure you use the helicopter and

you gently push them into a relatively flat area where you can

successfully put a net on them and they won't tumble down the side of the mountain.

Bull's-eye.

Now, it's all about speed and keeping stress to a minimum.

So, to limit the stress on the animals,

we put a blindfold on them so that they can't see.

When we take away that visual sensation, it calms the animals down

a lot and helps to make them relax quite a bit.

By targeting the female goats, Kent and his team maximise the

reproductive potential of the new population.

After a few quick tests, they're driven to their snowy

new home - Mount Dutton, a veritable goat utopia of unexplored peaks,

400km to the south.

And the final result?

So, when you look 10, 20 years into the future and you see that a

population that you helped transplant is established and doing

well and other people can enjoy it, it's a great feeling.

Is it a bird? Is it a plane?

No, it's a flying goat.

Obviously, the best way to redistribute this important population.

But I've got to tell you, that Kent and his team are not pioneers when

it comes to this extreme animal relocation.

Animals have been flying into new homes for years.

Just ask Idaho's beavers.

'20 beaver ready for the flight to Mountain Meadows.'

Yes, back in the 1950s, the Idaho authorities wanted to save

themselves the cost of building a dam so they decided to enlist

beavers to do it for them and they parachuted them in.

That's a bit of a bumpy landing.

'And a most unusual and novel trip ends for Mr Beaver.'

Look, look. He's OK. He's out. He's living.

That is one bemused beaver.

But thankfully, Kent and his helicoptering goats are proving that

delivery methods have improved a little bit since the early days.

From flying goats and parachuting beavers to a different kind of

rescue mission entirely.

700km from the coast of New Zealand is a strange volcanic

island - the Pyramid.

The most important place on the planet for an entire species.

The Chatham albatross.

The Chatham albatross is only found in the Chathams and there, even,

it only breeds on one small rock stack.

It literally is a pile of rocks coming out of the sea.

But the species is under attack.

It's very survival is in doubt.

Unlike the other albatross species, the threat isn't from commercial

fishing, nor is it disease or a rampaging rogue predator.

No, the problem for the Chatham albatross is elemental.

One of the biggest threats to Chatham albatross, actually,

is climate change.

The Chathams are lashed by storms all the time.

So the islands and the species are adapted to that, but when the storms

come from an easterly direction, that's what causes the havoc.

This wonderful papier mache model represents the pyramid and for

thousands of years, the albatross have been nesting on the north-east

side, protected from the prevailing winds.

The thing is, the soil here, which they make their nest from,

is very soft and easily eroded and things are changing.

Due to climate change, there's been an increase in the frequency

and the severity of the winds.

And the result...

..is that all of that soil is blowing away,

making it impossible for the birds to nest here.

So what can be done to save them?

Well, move them from the island.

Surely that would be the obvious solution?

Yeah. But the thing with albatross, you see,

is that they have a superpower and it's working against them.

When the young albatross fledge their nest, they wander widely

over the southern Pacific Ocean and they continue to do

that for a number of years until they reach sexual maturity.

Then, a homing instinct kicks in and they head back to the island where

they grew up and, do you know, sometimes, when they first land

on it, they will land only a matter of metres away from the nest

that they actually grew up in.

So move an albatross and it'll come right back to its nest,

a perfectly designed mound of insulating mud and vegetation,

home for the chicks' first five months.

So how do you undo thousands of years of evolution?

Well, Mike and his team had a plan.

In January 2014, they set about saving the Chatham albatross,

moving them to a new safe island, 50km to the north.

And for the plan to work, they had to target the chicks.

The adults' natural compass was too well engrained.

The pyramid would always be their home.

99.9% of sea birds will come back to the island they were raised from.

So we're taking these chicks and trying to establish a new colony.

They chose only the healthiest youngsters,

the ones old enough to cope with the separation from their parents but

young enough to accept a new island.

We're basically hoping that we can reprogramme their GPS

so that they'll fly back to the main island rather than the pyramid.

With the plan hinged on persuading the chicks to accept their new home,

Mike needed to perfectly copy the colony

and, most importantly, the nests.

And his solution? Well, it was beautifully basic.

For an albatross chick, its nest is its castle.

It's parents know to come back to that nest,

that's where it'll find its chick and that's where it'll be fed.

So it's engrained in these chicks to stay on their nest until they leave,

so we had to find something to replicate that nest.

And who would've thought a flowerpot was the ideal replacement?

Filled with rocks and peat,

it provided not only a comfy seat but fantastic drainage too.

But making the ultimate albatross nursery didn't stop there.

Mike needed to make the chicks feel safe,

so he's provided plastic bodyguards...

..enlisted the help of the local community

to become surrogate parents, delivering daily meals and he's even

playing mood music on hidden speakers.

And if he's successful, for the first time,

the Chatham albatross won't have all of its eggs in one basket.

With two colonies on two islands, Mike hopes the species will survive,

no matter what climate change throws at it.

This project's going to have several different measures of success.

The first one will be when the first birds return and breed.

So, for us, it'll be when we've got a core of birds that are starting to

breed and that's starting to grow to be a new colony.

But our overall aim is to try and future proof Chatham island

albatross in a changing world.

It'll be at least three more years before they know if they've been successful.

So it's all fingers crossed that the first of this new

generation of Chatham albatross will return to their safe new home.

Who'd have thought the best way to save a bird would be to plant its

chicks in a flowerpot?

Fantastic.

Has to be one of the best low tech ideas in conservation that I've ever heard.

Top work.

So, from flying goats and falling beavers to albatross in flowerpots,

moving to a new home is fraught with challenges.

'And a most unusual and novel trip ends for Mr Beaver.'

Finally, bizarre chimpanzee behaviour...

..and strange messages in prehistoric art.

But our first story starts here in the UK.

Cumbria, northern England.

A place where ancient legends and romantic poetry are woven into the hillsides.

But in November 2014, Dave Murphy was about to write his own chapter

in the book of the bizarre, when a strange figure appeared in the clouds.

Peace, we come in peace.

Get closer!

Dave and his friend were out wild camping,

finding secret corners of the country, far from civilisation.

I just love being by myself and getting out in the hills,

and just putting my tent up and waiting for the sunset.

I can't think of anything else to be doing in my life, it's my passion.

Pitching their tents on top of Dufton Pike,

they thought they'd left everyone else behind.

I've seen some amazing things on the hills when I've been out,

but nothing compares to seeing what I seen that day.

I just remember it being a nice morning,

the sun was shining and I could see the clouds sort of coming in,

and it just looked a lovely morning.

A strange, shadowy figure had followed them.

Oh, look at that!

How bright it is!

It comes and goes.

It can be there for a second, and then it can be gone.

Back again, look.

It's getting further away though, isn't it?

The figures inside can actually be small and then go large again,

so it was like it's sort of focusing in and out.

It's unbelievable, unbelievable.

Looks like two aliens, you know, Jonathan?

Look at that, look at that!

And Dave isn't the only person to have seen these strange spectres

in the sky.

All over the UK, people were uploading videos to the internet.

What on earth was it that these people were witnessing?

Well, they're known as Brocken Spectre,

and their appearance is all about perfect alignment.

When you get some elevation above a layer of cloud and the sunlight's

behind you, that's when you can sometimes see one of these eerie,

strange optical phenomena...

..that are to do with your shadow and the sunlight bouncing back at you.

So, far from being a spooky figure, the Brocken Spectre is in fact...

Well, it's you.

As your shadow is cast down onto the layer of cloud below you,

your shadow seems strangely distorted.

Your head seems very, very small and your legs very, very large.

This is simply the dramatic effect

of the perspective as a shadow

recedes away from you.

The other strange phenomenon is a halo of rainbow colours.

These tiny droplets of cloud scatter

the sunlight back at us,

and the way the sunlight is

scattered, is different depending

on the wavelengths. For this reason, we get this separation,

this ring of colours around the shadow.

The apparition is your own shadow, surrounded by a rainbow halo

created by the sun's rays reflected and refracted by the water droplets.

And for those of you who don't regularly climb mountains, never fear.

There is another place to see this bizarre phenomenon at work.

So they're just shadows.

There's no need to be scared of a Brocken Spectre.

Well, actually, legend has it that seeing one is a bad omen,

a really bad omen.

A foretelling of your own death.

Perhaps because stormy weather had closed in below you,

or you'd ventured too close to the edge to get a better look.

For centuries, we've gazed up into the skies, searching for answers.

And these days, science can explain some of these bizarre apparitions.

We know what they are, how they work.

But that, nevertheless, can't detract from their simply awesome beauty.

So, from legends in the sky to strange signs in the trees.

March 2011.

A research team are deep in the Forest of Guinea in Western Africa.

They were studying an area for the very first time when they noticed

something strange.

I was at the back of the group that day,

because I got caught in some thorns.

So when I caught up, the group had stopped and we were gathered around

these markings on a tree, which the main field guide had found.

They looked really innocuous.

I mean, it would be impossible to tell what they were.

We weren't sure if they were wild pigs,

or if they were human created or if they were cows.

What they'd found was utterly baffling.

Strange notches on a tree, and below them, large piles of rocks,

seemingly placed there deliberately.

Laura set up camera traps to see who or what had made them.

Two weeks later, she recovered the footage.

What we saw was really incredible.

It was a male chimpanzee arriving at the site, pausing,

looking around and picking up quite a large stone...

..and flinging it at the tree.

We didn't know what it could mean, we didn't know how common it was,

we didn't know if it was just a once off event.

So, a chimp throwing a stone against a tree.

What's so weird about that?

Well, the problem is, you see, explaining why a chimp would want to

throw a stone against a tree.

There's no obvious reason.

It is, in fact, a great ape mystery.

Anybody that's been to the zoo knows that chimpanzees can throw stones.

I mean, that's not new.

The really new and interesting thing is that they come back to the same

site with the same repeated behaviour,

and only at certain specific locations.

But as her cameras gathered more footage,

Laura realised this wasn't an isolated case.

This was a real phenomenon,

and it had never been reported anywhere before.

What we were seeing was something that had never been seen before in chimpanzees.

It seems like a new level of tool use. It was astounding.

So, what on earth were humans' closest relatives doing?

Laura quickly ruled out the most obvious answer.

Unlike other examples, termite fishing, cracking nuts

and making spears, this behaviour wasn't connected to finding food.

So we checked the area to check that there was no fruit trees that it

could be affecting, or any different kind of food source that it could be

related to.

And it really is quite sure that it's nothing to do with gaining food.

Could it have been a male status display,

an aggressive show of dominance that sometimes involves throwing stones?

No, it wasn't, because it wasn't just males doing this.

Teenagers and even mothers with babies had been captured by the

camera traps.

So what could inspire this ritualised act of chimpanzee vandalism?

Laura developed two main theories.

So, chimpanzees live in close-knit groups and they defend territory.

And so there's other groups around their boundaries,

so maybe these stone cairns are symbolic of a chimpanzee's territory

that they protect.

Theory one. It's possible that the rock piles are territorial markers,

a way for the chimps to declare their space in the forest.

But it's theory two that Laura feels is most likely.

Chimpanzees, during the day, they'll split off into subgroups,

but they'll often communicate with things like calls and drumming,

and doing a loud pant hoot.

And it was this call, the pant hoot,

that was Laura's most convincing clue.

It's generally thought of as a long-distance call.

It kind of starts out like hoo-hoo-hoo-hoo-ah-ah-ah-ah!

Often, when you see a chimp doing this,

if you can really study the community,

you see that other individuals will actually change direction.

It seems like there's signals being given that affect other members

in the group.

And so possibly this stone throwing is an add-on to that,

and therefore maybe it's a kind of chimpanzee Morse code.

So this strange behaviour could be a form of territorial marking.

It could be a form of communication.

But then, some truly extraordinary new evidence came to light.

Researchers across Western Africa started to look out for telltale

notches on the trees.

Three of the four subspecies reported nothing.

But sites in neighbouring Guinea-Bissau,

Liberia and the Ivory Coast reported positive sightings.

These groups either passed the ritual to each other,

or they've developed this behaviour entirely independently.

This wasn't an isolated incident.

It was occurring across the species range, and that meant that the

scientific community became immediately a lot more interested.

And one rather bizarre theory surfaced.

They seem to be responding to something in the space

that we can't see.

There's something in that space that they're returning to,

that is fascinating to them, that has a hold over them.

Is there a memory that they have attached to that particular spot,

like the death of a member of their clan, or a leader of their clan?

Or was there some other anomaly at that site,

like a lightning strike, or a fire,

or a particular storm that they witnessed together?

We might never have an answer to the question of why a particular space

seems to have become charged,

seems to have become electrified for these chimpanzees.

But similarly, we don't necessarily have good answers as to why it is

that our sacred spaces have become charged or electrified for us.

OK. Now, identifying these sites as chimpanzee sacred spaces

might seem a little crackpot. But, when you think back to our own past,

and how human beliefs were formed, it's not really as crazy as it sounds.

If we go back to the beginning of human beings as a species,

which is generally believed to be about 50,000 years ago,

we would be seeing a range of behaviours that looked very similar to this.

The religions that we have now would be the descendants of these

amalgamations of early human behaviours that would have looked

like these animal rituals.

Perhaps we'll never fully understand why these chimpanzees engage in such

bizarre behaviour.

But for Laura, this discovery is just the beginning.

I do think that we constantly underestimate other species.

And so, I think it's worth wondering what this could mean in,

potentially, a higher sense.

And I think the real thing that we should take from this is

how important it is to protect the future of these chimpanzees,

because I'm sure there's a lot more to discover that we haven't yet seen.

Who'd have thought it?

A few mysterious notches on a tree growing into such a great mystery.

But we really shouldn't worry.

Planet of the Apes? Well, it's not round the corner.

Well, not quite yet, anyway.

So, from chimpanzee rituals that tell us about the beginnings of

human religions, to early human religions that might just point

to a god of a very different kind. Something totally alien.

11th of May, 2002.

An expedition is exploring the deserts of Gilf Kebir,

the great barrier in the Egyptian Sahara.

And at 4.30 in the afternoon, with the sun burning down,

Jacopo Foggini sought out shade in a cave and made a startling discovery.

Thousands of cave paintings.

8,000 years old.

One of the most important prehistoric sites ever discovered.

The big question everybody's asking about this cave is,

"What the heck are these animals?"

These big animals.

And the beast, what is it?

Whilst most were fascinated by the strange images of headless

creatures, one archaeologist was drawn to something else.

Something everyone had overlooked.

When I arrived on the site, I did not believe my eyes.

I immediately noticed the tiny stencil hands.

There were 13 of them, and I thought,

"Wow, it's really different from any stencil hand I've seen before in my career."

Prehistoric handprints have been found at cave art sites all over the

world, from Australia to Argentina.

And in evolutionary terms, they're fascinating.

They provide one of the first insights into humans developing

a sense of self.

Look at that. It's a signature, a sort of prehistoric spray tag.

But the prints that fascinated Emmanuelle were altogether more bizarre.

What she'd found weren't just handprints.

Inside each of the 13 larger ones was strange, second, smaller print.

All of the experts had assumed that they were children's hands.

But Emmanuelle wasn't so sure.

We did some measurements on dozens of pre-term new-borns,

and even if they were matching in terms of hand length,

the proportions were really different.

With a probability of less than 0.01%,

Emmanuelle proved that humans hadn't made these handprints.

But who, or what, had?

My first hypothesis was, it could be monkeys' hands.

And for that time, 8,000 years ago,

imagine that people have taken monkeys under their shoulders and

stencilled their hands, it was really crazy to imagine it.

Crazy maybe, but impossible, certainly not.

But no matter which monkey she tested,

she just couldn't get the thumb in the right place.

Emmanuelle was at a loss, but there were some other theories

out there she couldn't ignore entirely.

Our first publication was about telling it's not human.

But we didn't find yet the solution,

so after that I got plenty of e-mails telling me,

"Would you investigate the alien path?"

And I thought, "But how can I measure aliens?"

But Emmanuelle wasn't quite ready to give up on a more terrestrial answer.

We did a lot of measurements on the hands of crocodiles

and the match was quite good, but it was not 100% convincing.

After nearly ten years, her search had become an obsession.

At this point, we had investigated the human path, monkey path,

the crocodile path, and no-one was really matching.

I have to confess, it began to haunt my dreams.

Determined to find an answer, she scoured the records and

discovered one animal, no longer found in the area,

that would have once walked the dunes here.

This desert monitor lizard had lived here 8,000 years ago.

I contacted a lot of crocodile farms,

and I realised they were also keeping a lot of monitor lizards.

So I asked them if they would enjoy to take part in the study,

and to my surprise they were all very enthusiastic.

Hunted for centuries by humans for their skins,

these throwbacks to the time of dinosaurs were in the right place

at the right time.

But could they be the source of the non-human handprints?

When I got the final result, I couldn't believe my eyes.

We got the closest match with lizards,

and they are actually matching with more than 85%.

But one vital question remains.

Why were they using these lizard feet in the first place?

We have no evidence of a reptile worship, but the fact that those

hands are stencilled exactly as the human ones are done,

it does testify of really different relationship to nature than the

one we have today.

Today, we consider that humans are separated from nature.

But in animalistic societies, people consider that

they are equivalent of any living entity in the world.

After ten years of enquiry,

I really feel happy to have found the solution!

So now I can sleep at night.

So, from humans to monkeys, from crocodiles to aliens and

finally to the desert monitor lizard,

what Emmanuelle has proved here is that to solve the perfect

prehistoric riddle, you've got to pull out all of the stops.

Determination is key.

From weird clouds bringing portents of doom,

to a chimpanzee ritual that sheds light on our own early religions.

And a prehistoric discovery that hints at a very different set of

beliefs entirely.

We've found that in our search for deeper meanings,

some of the answers can be found in the most unexpected places.

Next time... What so enraged this placid marine mammal?

Why has this guy got peanuts stuck to his head?

Pull.

And a glowing underwater wonderland, invisible to the human eye.

Blink! Unbelievable!