Original subtitles

Created by fire and titanic upheavals of the Earth,

islands make up one-sixth of the landmass of our planet.

They are lenses through which to study

the complex workings of evolution.

Tropical islands have been important in the understanding

of evolution ever since Charles Darwin visited the Galapagos

early in the 19th century.

We're going to visit three very different tropical islands

to see what they can tell us about evolution, even today.

Islands are the natural world's testing grounds,

full of novel experiments in natural selection,

and evolutionary wonders.

But there's much more to evolution than the survival of the fittest.

The phrase wasn't even in Darwin's first edition

of The Origin Of Species.

I'm exploring other major influences.

Geology,

geography...

Hello!

...isolation and time.

You found this?

Yes. Giants' bones.

I'll be charting the life cycle of islands,

from birth and colonization

to the burst of evolutionary creativity

that often accompanies maturity...

They take the leaves so delicately.

...and what eventually happens when an island grows old and nears its end.

You can almost feel this unforgiving rock return, ultimately,

to sea level.

Places of extinction as well as creation.

Our story will reveal evolution in action.

We've just discovered new species of the mouse lemurs.

So mouse lemurs are still actively evolving? Yeah.

And how life generates abundance,

even from a blank slate.

Islands are the ideal place to understand the rules

that govern evolution.

In this first episode of the series, I want to investigate how

animals and plants colonize and evolve on a newborn island.

The remote Pacific island of Hawaii is home to

creatures as unusual as carnivorous caterpillars...

...as hardy as volcano-adapted plants

and acid resistant shrimps.

And as exquisitely adapted to their environment

as nectar-feeding honeycreepers.

Here, too, is the secret of how one lucky species

can transform into many.

A new island is a new opportunity for life.

An oceanic island is a kind of natural laboratory

where we can see evolution playing out.

It's the place to understand the rules that might govern

the origin of new species.

2,400 miles from the nearest continental landmass,

Hawaii is the most isolated group of islands in the world.

Its eight major islands are all volcanic

and none of them are over five million years old, making them

geological infants, many millions,

even billions of years younger than the continents.

On Hawaii, everything is volcanic, everything is lava.

Even the sand is made of tiny little bits of broken-up lava.

This is the kind of place that arises from the sea due to volcanic activity

and creates a tabula rasa for evolution.

Before life of any kind can exploit such opportunities,

it must first face one of the greatest challenges in nature.

How does an animal or plant reach a newly-erupted volcanic island?

Very few organisms have learned the trick. But one that has...

...the coconut.

Its large fruits are covered with a buoyant coat and inside,

there's a nut with lots of nourishment in it

and indeed, some flotation, a bit of air.

On ocean currents, they can be carried huge distances

and when they land on a sandy beach almost anywhere...

...they can germinate.

Their plentiful supply of nutrition means that a strong shoot

can put down roots.

As a result, sometimes it's thought with man's help,

they have colonized virtually all the tropical waters of the Pacific.

The coconut palm has learned the trick of wide dispersal.

But for almost all other organisms, it's much more sporadic,

much more chancy, much more difficult.

Water is an obvious route to virgin land

for those animals and plants adapted to it.

Bravely battling the currents to feed on the algae that cling to

the underwater rocks, turtles haul themselves on land

to bask, most mornings.

One of the first animals to arrive on a new volcanic island like this

would have been a seagoing turtle.

They would have loved to come in, bask in the sun

and lay their eggs on the sandy shores,

especially if there were no natural predators.

Even so, the Hawaiian form of the green turtle is often

regarded as a special subspecies, endemic to the island.

Green turtles are found all over the Pacific.

But on Hawaii, they've become endemic,

a word derived from the ancient Greek, meaning "native".

Long isolated from others of their kind,

through natural selection, each new generation has become

increasingly better adapted to the local environment.

Turtles evolve very slowly.

But one day, Hawaiian green turtles may be so genetically different

from others of their kind, they will no longer be able to breed with them.

They will have become a new species.

This process is not always so slow.

In fact, on the isolation of an island, some plants

and animals can rapidly evolve into not just one, but many new species.

Scientists call this adaptive radiation.

And one of the best examples of it anywhere in the world

is found on the Hawaiian island of Maui.

Here live numerous species of Hawaii's rare honeycreepers.

And among those most exquisite adaptations is the shape of the bill.

This is what Darwin observed at

the very cradle of the idea of evolution in the Galapagos Islands.

Another group of finches, another group of modifications

to bill form, in adaptation to mode of life.

The first finches arrived on Hawaii five million years ago

and quickly radiated and adapted into five distinct lifestyles.

Insect-picking gleaners,

generalists,

long-beaked nectar eaters,

seed lovers

and parrot-beaked bark pickers.

But each of these different lifestyles

has spawned multiple species.

The total tally of these endemic birds once exceeded 50.

Hoping to glimpse one of Hawaii's iconic honeycreepers for myself,

I join Hanna Mounce of the Maui Forest Bird Recovery Project.

More than a mile above sea level, Hanna takes me on a long hike

to reach a high belt of surviving native forest.

After a long trek, we reach our destination.

And it's full of evergreen ohia lehua trees.

DELICATE BIRDSONG

(What I can hear now is a sort of subtle birdsong.)

(Yeah, you can definitely hear them now.)

(We're hearing three right now.)

You can hear Apapane, the liwi and the Maui 'alauahio.

(I suppose they're feeding on nectar if they can find it.)

(Yeah, so they're following mainly the ohia lehua blooms

(but because there's not really any flowers right now,

(they're also feeding on a lot of insects.)

To get a closer look, we first set up mist nets.

By alternating pre-recorded honeycreeper calls

from speakers positioned to either side of the nets, with luck,

Hanna and her colleague Chris will lure down these very rare

and notoriously shy birds to tag them.

(So there's a Maui 'alauahio up there right now.)

(You can see that one, yeah.)

The first honeycreeper to get snagged is an insect eater.

So what's this guy called?

A Maui 'alauahio.

Its English name is the Maui creeper which is much easier.

The Maui creeper. Is it endemic to Maui?

Endemic to Maui.

Efficient.

Cute!

So we have virtually exactly 30g.

So this is an absolutely charming small honeycreeper.

An insectivore, I guess.

Yes, and it's endemic to Maui Island.

OK, so I'm going to slip him back into there

and I'm just going to make sure his head is up at the top.

Yeah. Is that all right?

Yep. There you go.

And this is an adult male.

He's at least two years old.

We can tell that by his real yellow plumage.

The oldest honeycreepers that we've found in this forest are,

you know, 15-17 years old.

That's old for a small bird, isn't it?

For a 13g bird, that's pretty old!

THEY LAUGH

So does it have other anatomical adaptations for forest life?

It does.

Creepers aren't very good flyers, so they have short,

rounded wings and they can really hop between trees

and kind of work their way through the forest.

And they're really adapted for the understorey of the native forest.

You see them upside down and sideways and everywhere,

trying to creep along the branches

in order to chase the inverts and bugs and moths and things.

Just a slight deflection on the bill.

So, how does this little bird fit into the great radiation

of the honeycreepers on the Hawaiian Islands?

It's one of the older honeycreepers. Diverged very early.

The different bill specializations in honeycreepers are quite

amazing and, unfortunately,

we've lost the most specialized of the birds that we had.

A lot of the honeycreepers that have not gone extinct

are the more generalist,

because they were able to hold on in changing habitats.

Further down the mountainside,

another set of nets has snared Maui's rarest honeycreeper.

The Kiwikiu, or Maui parrot bill,

uses its specialized bill to dig out grubs from beneath tree bark.

Um...

So there she is.

Maui parrot bill.

Let's see your bill.

You can see how she uses that bill on my finger. Yeah.

Does it hurt? No, not too bad.

Wow! This, it's specialized for ohia trees, presumably?

Ohia and koa, but specialized for the native forest,

so he uses the bill like a chisel

and can really have a lot of control over that lower mandible

and dig out wood and bark, kind of like a continental woodpecker would.

And this is really, really rare.

These are the most endangered birds on Maui

and one of the most endangered in all of Hawaii.

There are only about 500 in existence.

These guys are very long-lived. They only have one chick per year.

Chick stays with its parents for sometimes a year,

so they're very rare, very slow reproducing.

Well, perhaps we should let her have some peace.

The third and final honeycreeper the nets snag is called

an Hawaiian amakihi.

Its long, thin bill has evolved to help it feed on nectar.

The ancestors of today's honeycreepers were finches that

were probably blown off-course during their annual migration.

Genetic studies suggest they made an incredible 6,000 mile

journey across open ocean, all the way from central Asia.

The early bird gets the worm.

Or in this case, inherits the island.

And this same extraordinary story of a single founder leading to

an adaptive radiation has happened again and again on Hawaii.

My next stop is the protected rainforest

of the neighboring island of Oahu.

I'm off to see another species whose ancestors were also blown to

Hawaii on the wind.

But this one is a plant.

A member of Hawaii's park service guides me to a location where an

endangered member of this radiation is being reintroduced to the wild.

How are you doing? Good. How are you? Good to see you.

Chipper Wichman, president of Hawaii's National Tropical Botanical Gardens,

is on hand to tell me its biography.

Here we are in your natural habitat.

Their oldest ancestor arrived here, dispersed here by wind.

It's just a phenomenal event.

So, what are the chances of that happening? Well, think about this.

We're the most geographically isolated group of islands

anywhere in the world, thousands of miles from any continental area,

and I once had a professor who talked about, you know,

what is the chance of something actually dispersing here by wind?

Blowing through the wind and landing on these islands, reproducing itself.

He said the chance of that is very, very, very, very, VERY improbable.

He said, really, what does that boil down to?

Give it enough time, it's guaranteed to happen.

The plant in question is a specialist lobelioid

that has co-evolved with the honeycreepers.

So, let me show you one of my friends here.

This is a Cyanea. This is Cyanea crispa

and it's flowering right now.

It's a really wonderful-looking flower.

Yes. Here you can see the curved corolla

and how this curved shape co-evolved

with the curved beak of the honeycreepers,

provided a little nectar reward for the bird

and in return, it would get the pollen from the male parts

of this flower, from the anthers here.

So, the bird would get the pollen on its head

as it got its nectar reward, it would go on and would carry it

to another flower and was a very effective pollinator.

And then, afterwards, a fruit?

And then, comes back when the seeds are matured to eat the fruit,

so this species evolved a fleshy fruit that was then

eaten by the birds and dispersed to other parts of the island.

Adapting from being a wind-dispersed ancestor to being a fleshy fruit

that could be dispersed by birds was one of those

strategies for exploiting the many,

many niches that are available in the Hawaiian Islands.

So, different species for different altitudes presumably? Absolutely.

And different habits, as well? Some shrubby, some treelike?

Some arborescent ones, some shrubby ones,

some vegetative ones.

I mean, the story of evolution

in this tribe of lobelioids is simply amazing.

This lobelioid is just one of 126 species endemic to Hawaii.

All of them descended from one ancestral species.

Sometimes called the founder effect,

it's another story that highlights the rich evolutionary rewards

of being the first to arrive on a remote island.

The founder effect helps explain how Hawaii, at just 0.2% of the size

of the continental United States,

nonetheless contains nearly 15% of all US species.

Another all-important factor is Hawaii's sheer ecological variety.

No other island group in the world goes from cold desolate mountaintops

to dense wet forest...

...and tropical beaches in the space of only a few miles.

It's the sort of place where almost anything can find a niche to thrive.

If it can get here.

One species that was carried here on wing and wind

is the fruit fly Drosophila.

Once alighted, a founding species took adaptive radiation to extremes.

Astonishingly, genetic analysis has revealed that all 600 modern

species of Hawaiian Drosophila

are descended from a single pregnant female

that arrived here more than five million years ago.

Someone who gets a buzz out of flies is entomologist Dr Steve Montgomery.

So, Steve, we have before us a mere four files containing flies.

I notice nicely patterned wings.

They are spots that help the females

recognize males of their own species.

So, what about this guy?

Well, Drosophila silvestris, it lives in the forests of

the Big Island of Hawaii and only that island,

and they like Lobelia plants.

This guy, a narrow triangular shape, rather different.

That would be Drosophila grimshawi

and it seems to be the most polyphagous.

It has a wide choice of food plants,

so the female will select akia plant,

which has a lot of toxic chemicals, most flies won't even touch it.

And last but certainly not least.

Heteroneura. It's the only species in the Hawaiian Islands

which has a hammerhead.

Only in the males and it's used in a competition, to dominate.

So, it's one of those head-to-head fights, is it?

Head-butting much like the rams and the sheep species will do.

When a female's ready to find a mate, she will come by there

and the last one standing is the one that gets to make her an offer.

A vast abundance of fruit flies on Hawaii created the ideal

opportunity for a fly-eating insect to thrive.

But Hawaii had none

until another ancestor was also blown here by the wind.

A caterpillar normally eats shoots and leaves.

This one has disguised itself as a twig.

As this unsuspecting fly approaches...

The ultimate endemic, the Hawaiian carnivorous caterpillar.

After their arrival on these islands,

an abundance of fruit flies offered them an unprecedented opportunity

to swap vegetarianism for a more nutritious protein-based diet.

Steve was the scientist who first discovered this bizarrely

modified inchworm caterpillar.

So, you actually made this discovery yourself?

Yes, I was curious enough to bring it back

and offer it some of the thousands of flies in our lab, and people

couldn't believe it when I told them I had an ambushing inchworm.

Now, is that that unique to Hawaii? This behavior is indeed unique.

It evolved in Hawaii and it worked in Hawaii,

because there weren't any praying mantises, or mantispids,

or other raptorial predators,

so an unlikely candidate like an inchworm

could occupy the carnivore niche.

So, we have 18 species of ambushing inchworms.

That's quite a mini radiation, isn't it? All of its own.

Well, they cross that adaptive zone.

They exploded into... Every island has at least four or five species.

So, a story you've met before.

The opportunities are available and they left the flowers, or in

addition to the flowers, they added on live prey to their diet and

through changes in behavior, bit by bit, it became an obligate predator.

They'd rather starve than switch back to a vegetarian diet.

It can wait six weeks between meals and this is a large meal.

I won't have to feed it for another month.

Of the 18 species of carnivorous caterpillars,

more than half have evolved to become obligate predators.

In other words, they have specialized to such a degree

there's no turning back.

So when one of these gets hungry...

...it would rather eat its own kind than a plant.

But being a caterpillar of any kind,

let alone a fruit fly,

provides opportunities for other colonists to make a good living.

Today, they can be found all over the Hawaiian Islands.

Spiders.

The one I hope to examine today is often found high up in the canopy...

...where one of a team from the University of Hawaii at Hilo

on the Big Island, Brendan Cote, is searching.

Down below, his colleague, Ellie Armstrong,

is checking the leaf litter and lower branches,

cos in Hawaii's native forests,

spiders have adapted to live almost everywhere.

It might not look like a giant,

but many of this spider's relatives

are barely visible to the human eye,

making this moth hunter a relative colossus.

So this is Orsonwelles. That's its real Latin scientific name?

Real Latin name, yes.

So this guy is in the family Linyphiidae and generally,

linyphiids are actually quite small sheet web spiders, so they'll... Ah!

That doesn't look like a particular giant to me.

Presumably, was this named because Orson Welles was known

both for his - what shall we say? - stature,

in intellectual and other directions?

Sure, stature and charisma, maybe. Right, OK. Well, it's charismatic.

Right. So this is a giant among its kind? It is, yeah.

This is probably the biggest spider in the family Linyphiidae.

They're normally really, really tiny sheet web spiders.

So although this is an interesting thing about island gigantism,

we tend to think that means the thing is the size of a football or bigger,

but, of course, if you start very, very small,

this is still a giant. Yes, relatively.

It's relatively large, I should say.

This giant may be the big-name star,

but another endemic Hawaiian spider has evolved to steal the show

from right under Orsonwelles's mandibles.

So this guy is Ariamnes and as you can see,

it's really brilliantly gold.

What's interesting about these guys is some of them are kleptoparasites.

Which means...? Some of them will actually go in other spiders' webs

and steal their prey. Oh, yes, the shoplifting ones. Exactly.

Klepto, yes. Yeah, so kleptoparasitic, yeah.

Even though he seems a little clumsy, he's very sneaky.

Ellie and her team still don't know

how many spiders live on the Big Island.

It could be many hundreds.

So, Ellie, how do spiders manage to get to a remote place

like the Hawaiian chain in the first place?

So spiders can disperse amazing distances

across thousands of miles of ocean

and what they generally do is the spinnerets

on the end of their abdomen,

they release silk and then the silk will create a balloon

that the wind can then catch and disperse the spider

across to these really remote island chains like Hawaii.

But some larger insects, like moths, possibly used a different trick

to make the 2,000-odd-mile journey from either Asia or America.

In fact, they may have used stepping stones.

To get down to the tectonic truth

of how an island's geology determines its evolutionary destiny,

I'm bound for Pu'u 'O'o, an erupting volcanic vent.

Now we're coming towards the summit and you can see the smoke.

This is what the creative process looks like.

And I can see through the clouds...

...the lava lake. It's a sort of orange from here,

but, of course, it's unbelievably hot liquid magma,

liquid rock itself, where the lava is coming up

from deep, deep plumbing into the mantle,

the very birth of new land.

It spews more or less continuously.

The light is catching fresh lava

so that you can see the tongues feeling their way to the low ground.

Pu'u 'O'o is the latest outlet for a massive outpouring of lava

from deep beneath the Earth's crust

that is still making the Big Island bigger.

On the lip of the giant Kilauea caldera,

I meet Don Swanson of the Hawaiian Volcano Observatory.

At the present day, the Big Island, Hawaii itself,

is the youngest and therefore the largest of these volcanic islands.

It's still active.

There's abundant evidence of that.

That's correct. And still growing. And still growing.

The volcano has been growing every time that lava goes into the sea.

What's also forgotten, though, is that the island is growing up.

Every time that a lava flow erupts under the surface,

even if it doesn't expand the island, it is building it higher.

But a volcanic island doesn't grow indefinitely.

One day, it will stop spewing lava and start sinking back into the sea.

This life cycle is tied to its geological position

on the Earth's shifting tectonic plates.

So how does that work, Don?

How does that work from a perspective of the way geology

is in control of an island's fate?

There is a zone in the mantle

that is hot enough for rocks to actually melt.

That's many kilometers down? Probably about 100km or so down.

Then this has to be rising into a plate

of the Earth's crust that is moving across that hotspot.

When that magma reaches the top of the plate,

it erupts to form a volcano.

But now the plate is continuing to move, move, move, move,

and so its connection with the plume carrying the magma

is more and more tenuous and eventually it snaps.

Then a new volcano forms

and then you go through the same process again,

so this movement of the plate toward the north-west, over the hotspot,

creates volcanoes after volcanoes after volcanoes

and that's been going on for 70 million years or so.

And those islands must have had life on them and probably life moved

then down the chain to the younger islands as the older ones sank.

Starting on the coast of Siberia,

we can track the now vanished volcanic islands

created by the hotspot using undersea bathymetric data.

As we move east, we trace millions of years of history

past the sunken remains of ancient islands to atolls

and reefs just beneath the surface,

all the way to the hotspot's current position beneath the Big Island.

SONAR PING

By hopping from one island to the next,

a handful of founders spawned more than 10,000 modern species

of terrestrial invertebrates.

Other arrivals produce some descendants

capable of rising to the greatest environmental challenges.

Hawaii's most extreme conditions are found above the cloud line.

On the highest part of the island of Maui

lies the spectacular Haleakala National Park.

Its volcanic cinder slopes are parched

and almost completely devoid of life.

Yet one species has adapted to living conditions of 25% less oxygen,

50% more harmful ultraviolet light

and temperatures that regularly plummet to zero.

It's a distant relative of the humble daisy.

Its hundreds of delicate roots gather nutrients for years

before a single burst of reproductive brilliance.

Though I'm rather surprised to find it living in the summit car park.

10,000 feet up,

on top of a volcanic mountain in Hawaii,

lives a very special plant.

The silversword.

This is its earlier stage, its rosette stage,

a tight bunch of leaves

and on each leaf,

silver hairs.

They serve both to reflect the sunlight

and to prevent water loss.

This plant lives in really extreme conditions.

It's biding its time.

The rosettes get larger and larger, saving up energy.

Then they erupt into a flowering spike, having saved up enough energy

to produce an enormous number of flowers.

This plant has just finished flowering and it reveals

the true biological affinities of this extraordinary plant.

It's related to the daisy, or the sunflower family.

A huge island giant, if you like.

Produces tens of thousands of seeds from a single plant.

When it's flowered,

it dies.

This sad remnant is all that remains behind of the silversword.

It's dead.

At the opposite end of the altitude scale,

a remarkable species lives in the extreme conditions

created by recent volcanism.

Few creatures tolerate living in the acidic water of volcanic rock pools,

but every challenge is a potential adaptation.

One that rises to it is hidden in the tiny crevices of this porous rock.

It's a diminutive shrimp.

At the Waikiki Aquarium in Honolulu,

the director, Dr Andy Rossiter, has been studying specimens

gathered from a variety of different rock pools.

One adaptation is their very small size.

That is actually the adult size.

It's probably about half a centimeter, 5mm?

So they are a shrimpy shrimp? They are a shrimpy shrimp, yeah.

I notice that all the jars have different figures for acidity.

Most of those are all rather acid. Yes.

So is that another adaptation?

That's another adaptation, they're called acidophilic,

which means they like, or can tolerate, high acidity.

Descended from ocean-going shrimps,

the Hawaiian red shrimp has evolved

to survive entirely in volcanic rock pools.

These appendages look not unlike those of a normal shrimp. Correct.

They're just the basic shrimp plan,

but the thing to notice are the large eggs. That's on the back? Yes.

Maximum in this species is about 20, so very few, large eggs.

Which for a crustacean is a very small number. Very, very low number.

When the larvae hatch, they themselves are large

and the larvae have a yolk sac,

which means they don't have to disperse,

they can essentially stay in or near the habitat where they hatched.

Because red shrimps have evolved

never needing to leave their home pools,

there's no genetic exchange between different populations.

And this is prompting them to evolve into new species.

Some of the populations have bright, bright red shrimps.

Others have clear with no red at all and others have red and white bands.

Research has been done on their genetics

to see how closely related they are

and there are eight separate populations

within the entire Hawaiian Islands.

So would it be an exaggeration to say that these are eight species

that are kind of in the making?

Absolutely. Potentially in the making.

They differ by about 5% in terms of mitochondrial DNA.

Just to put it into perspective,

humans and chimpanzees are 98% similar.

These guys are 95% similar.

This is how speciation begins.

Isolated from others of their kind,

the red shrimp is separating into as many as eight new species,

each adapted to the very specific conditions of their own homes.

But it's a two-way process.

Geology may divide populations,

but other species can transform the volcanic rocks themselves.

This is a fern, a tree fern,

and here it is growing in naked lava.

But ferns have minute seeds,

spores - they're so tiny, they can be brought in on the wind.

If they can find a place in the tiniest crack,

they'll grow, they'll germinate,

and that's a terribly important thing,

because they begin to make soil.

Over time, much of this harsh lava will be broken up by ferns

and bacteria and turned into earth.

Ferns are found all over the world,

but Hawaii has evolved its own specialist soil-making tree,

the 'ohi'a lehua.

This is a small 'ohi'a tree

that's taken root in, well, still quite bare lava.

It's already flowering with these beautiful red flowers.

Given time, not a huge amount of time,

it will turn into lush forest.

A lush tropical island populated by numerous plants

and many small invertebrates is a habitat

that can potentially support larger animals.

One of the largest arrived by accident

more than half a million years ago.

BIRD CALLS

Today, it seems determined to lead me around the houses.

This is the nene.

It's a very handsome goose

and another Hawaiian endemic.

It's actually very closely related to the Canada goose.

It's a little bit smaller,

but their skeletons are apparently almost identical.

You can imagine a Canada goose getting severely blown off course.

The survival of the nene owes quite a lot to Great Britain.

When the population had shrunk to just a few pairs,

some of them were transferred by Sir Peter Scott

to the wildfowl center at Slimbridge.

There they were bred on until the population had increased to the

point where they could be reintroduced into the wild.

Since then, they've done very well.

And here they're thriving.

It's a success story.

The nene's ancestors were strong fliers.

But now, like many island birds,

its wings have grown weak,

it can barely carry it between Hawaiian islands.

Flightless birds were once common on Hawaii

and in Honolulu's Bishop Museum,

they have one of the largest that ever lived here.

We're going to look at one of the extinct giants

of the Hawaiian Islands

and Molly Hagemann, here in the Bishop Museum,

is going to show me.

So this is moa-nalo,

which is an extinct goose-like duck.

So one of the main features is the sternum,

is completely smooth.

That's the sternum? Correct.

On a bird that can fly - this is from a nene.

This is contemporary.

You can see the difference inside in size

and, obviously, the one feature that's missing from that

is the large keel.

It's what we call on the chicken a breast bone. Exactly, yes.

This is where all the flight muscles would attach.

This lost flight... Well, no predators, presumably? Exactly.

It didn't need to invest that energy into a keel

and flight muscles

and instead it redirected those resources

to produce more robust limb bones.

So that's a limb bone? Mm-hm.

This is from a nene, a contemporary bird.

I don't have to be a particularly perceptive scientist to see

that one is three times as robust as that one.

Exactly.

So here we have the idea that if you don't use something,

in this case flight muscles,

then you tend to lose it?

Exactly. Three million years ago

something similar to a mallard would have colonized the Hawaiian Islands

and then rapidly changed into what we see here.

A ground dwelling, large duck?

Who ate them up?

Probably the Polynesians that colonized Hawaii

because they were probably slow-moving.

Erm, they were large, they probably tasted pretty good.

It's a bit like a Hawaiian dodo,

except the dodo we know was derived from the pigeon family. Mm.

Here's the duck family producing something else. Yeah.

The moa-nalo fell victim to an invasive species.

Man.

Polynesians made Honolulu their capital in the 11th century,

bringing with them livestock and introducing new crops.

Hawaii was changed for ever.

The micro-propagation laboratory of the Lyon Arboretum

is a modern-day Noah's Ark.

These test tubes contain more than 100 species

of critically endangered Hawaiian plants.

The samples here share common vulnerabilities

associated with island life.

Descended from only one, or just a few ancestors,

long isolated,

they have also become highly specialized.

They are often outcompeted by new arrivals.

Out in the greenhouse is a familiar plant,

that is being kept here for its own protection.

Ah...

This is the one I'm after.

Even plants can lose

protective characteristics in the safety of an island.

And this looks like a mint.

It is a mint but it's a mintless mint.

It's lost what it didn't need

which was the protective chemicals that protect most mints

from being eaten by herbivores.

It's the thing we like because of its delicious smell.

This one doesn't have any of those,

it's not gone to the trouble of making those chemicals

any more because it didn't need them.

Well, it didn't need them in the past.

It needs them now because, of course, pigs, sheep and other

herbivorous animals have come in and decimated the wild population

which is why it's here among all the rare and protected plants.

And it would be quite useless for flavoring your garden peas.

By some estimates, before humans arrived,

only one new species colonized Hawaii every 35,000 years.

Once Europeans made contact,

that number leaped to an average of one per month.

For centuries, the Hawaiian Islands were unknown to Europeans.

But all that changed when Captain Cook discovered the group

and by the time Cook made his third visit,

and prepared this map in 1779,

it was with the latest technology of the time,

Hawaii's place in the world was fixed for ever.

It was doomed to change.

Within ten years, missionaries were declaring it

the new Eden

but it was already a fragile Eden.

To get an idea of the sheer scale of new species that have

arrived on Hawaii, after Europeans made contact,

I visit Manoa Falls,

one of the most famous beauty spots in Hawaii.

To help me see the proverbial wood from the invasive trees,

I rejoin Chipper Wichman.

So it's an extraordinary thought that this whole forest

has grown up in, what, 100 years, or so? Yeah.

This was probably... Everything you see here is 100 years or less.

I mean, to me, that pink flower looks somewhat like a banana.

It is, it's a flowering banana.

It was introduced actually as an ornamental banana.

Most of these plants were all brought here intentionally.

With unintentional consequences? Absolutely.

That's a hell of a tree.

Albizia was actually brought intentionally to

Hawaii in 1917 as a potential tree for reforestation in Hawaii.

This particular tree right here is probably less than 50 years old.

Good God!

What else... I can see a conifer there.

Don't tell me that's another invader, is it?

Well, we call it, instead of an invasive species,

a naturalized species.

It's been able to establish itself independently.

It's a relative of the monkey puzzle. It's araucaria. Araucaria.

Originally brought here by the sailing ship captains who

wanted replacement masts for their ships.

In a curious way, we've got a world sample of plants here. We do.

Which is, in one way, wonderful but another way, tragic.

I'm not sure how to describe it.

It might seem like the beautiful plants of Manoa Falls are harmless,

and indeed many non-native species cause little harm...

But on a small island,

even a single invasive pest can wreak havoc.

Biologist Chris Warren shows me an innocent-looking Jackson's chameleon.

So we've got a male here.

The one that looks like triceratops? Like a triceratops, exactly.

And a female. She has no horns.

So presumably there is sexual selection working on...

Males, as usual, are the horny ones! That's right!

CHRIS LAUGHS

When did he and she arrive here in the wild?

They were released as pets inadvertently, or invertently.

Maybe sometime in the 1970s.

They escape for whatever reasons

and then within a pretty short period of time,

they're so abundant that it's almost not feasible to remove them.

Well, they're pretty, little animals,

but why should we be worried about what they do?

They eat every invertebrate that they find,

including lots of rare, threatened and endangered insects.

Hawaii doesn't have native reptiles.

Just the marine ones, sea turtles and things.

So no terrestrial ones, so presumably these guys...

What, they weren't expected and there's nothing to prey on them?

Exactly.

Unfortunately, they have spread maybe as much as they're going to.

That's just since the 1970s. Yes.

That's a lot of damage in a short period of time. Mm-hm.

Geological time, it's nothing at all. It's nothing, yes.

But there are other invisible killers brought here by man.

Mosquitoes arrived with European and American ships in the 1800s.

They spread avian malaria

to Hawaii's native honeycreepers,

causing devastation.

Today, most honeycreepers only survive where mosquitoes cannot.

Up at altitudes of several thousand feet.

But, remarkably, after two centuries of exposure to malaria,

some species of honeycreepers have started to move down

to lower elevations again.

It seems they've evolved a resistance.

This is one of the fundamental rules of all evolution,

it never stops.

The beautiful lao Valley on Maui

is a sacred place to native Hawaiians.

It's a good spot to ask how Hawaii's rich evolutionary

diversity can be saved from extinction,

with conservation scientist, Sam Gon III.

You know, just as there are endemic plants and animals here,

there are also endemic cultures.

Hawaii and Hawaiians were in this place from 1,000 years ago

and they existed here in 100% self-sufficiency

with a remarkably small ecological footprint.

Today, our self-sufficiency is down to 15%.

Which means almost everything has to be bought in from outside?

That's right. Which means, it's certainly not sustainable.

No, if that influx of goods were to stop,

in three weeks' time we'd probably be eying each other hungrily.

You know...

things would be bad.

You're not a man given to despair, are you?

No, you have to be an optimist to be in conservation, I think.

I think so too.

Everywhere that I go, I see places that have degraded

from when I first saw them.

I also see places where, with just a little bit of effort,

keeping the non-native animals out

and removing the most aggressive weeds,

that the natives, given half a chance, will actually

come back and thrive.

Combining the wisdom of the past, with the science of the present,

to reduce our ecological footprint,

it seems like a good starting point for any conservationist.

The question is,

to what extent can a native Hawaiian diet sustain me?

For 1,000 years, Hawaiians were able to

live off the land of Hawaii in a self-sufficient way.

This would've been a kind of rather typical repast.

First of all, we have poi

which is made from the taro root.

It's a bit bland

but it's not unpleasant.

I'm told it's terribly nutritious.

So much so that babies can be fed on it.

The poi goes particular well with the lau lau.

This is lau lau.

It's typically pork wrapped in taro leaves,

cooked in hot stones,

often buried for 12 hours while the stones do their work.

So the pork is...

...deliciously tender.

Mmm...

The taro leaves suffuses the meat as well.

It's really delicious.

The taro leaves themselves taste a bit like a

slightly coarse spinach or chard.

For dessert, something prepared from the insides of a coconut.

It's called haupia.

It's like a rather thick yoghurt.

Mmm. It's actually delicious.

I'm sure it's very good for you too.

As for eating all this lot,

if I can manage to finish it off,

I'd probably suffer from something called kanak attack.

Which means a bad attack of wanting to have a long sleep

before I could face any more food again.

Volcanic islands like Hawaii and the species they generate

live fast and die young.

Most will be reclaimed by the sea

after a few million years.

But a few islands are almost immortal.

In the next episode, we visit Madagascar.

Not a volcano but a fragment of an ancient continent

more than 90 million years old.

And here, the vastness of time has created an extraordinary

evolutionary wonderland.