Last of the Giants Ice Age Giants

Two and a half million years ago,

life on Planet Earth faced the dawn of a new era.

The Ice Age.

Now we can go back in time.

Because out of the permafrost...

..from deep inside caves...

..and from hostile deserts...

..the astonishing remains of giant animals are emerging.

How amazing to be one of the first people to see this ancient creature.

The Ice Age was the last time such creatures would walk the Earth.

A lost Eden with mammoths taller than any elephant,

cats with seven-inch teeth,

and some of the strangest beasts that have ever existed.

I'm fascinated by what the remains of ancient animals can tell us

about them, and the world that they lived in.

Using new scientific advances, we can reveal how they lived,

and why they died out.

Come with me, back to the Ice Age.

A world ruled by giants.

For tens of thousands of years,

ice had covered half of North America and much of Europe.

Huge swathes of the Northern Hemisphere had been locked in deep freeze.

Then around 18,000 years ago, a great thaw began.

At last, the Ice Age was releasing its grip.

From Siberia to Scotland, from Alaska to the Hudson Bay,

the ice sheets went into retreat.

Water, warmth and life returned to the landscape.

Even after thousands of years of brutal cold, the world

was still home to millions of spectacular giants.

Mighty Columbian mammoths migrated across the coastal plains of California.

Sabre-toothed cats were on the prowl from Los Angeles to Miami.

Woolly mammoths and woolly rhinos roamed the steppes of Siberia.

Giant armoured glyptodonts basked in the Arizona swamps.

The future for the megafauna seemed bright.

So why do none of these spectacular giants roam our world today?

In the Northern Hemisphere, the continent which saw most

extinctions was this one - North America.

For hundreds of thousands of years, huge animals had roamed across this land.

They've long since disappeared.

The causes of those extinctions have sparked fierce debate.

It's a difficult mystery to unravel, but the remains of the megafauna themselves

hold clues to their demise.

These ancient remains have a story to tell - if you know where to look.

One of the most poignant cases is that of a mother.

This is the University of Michigan Museum of Natural History, home to some remarkable animals.

And the stories of their lives and deaths encapsulate this mystery.

These are mastodons, extinct relatives of elephants

and mammoths, and this one is a female. Her name is Owosso.

Owosso was one of the last surviving mastodons.

And she is SO special, because hidden deep inside her tusks,

she kept a secret recording of her tumultuous life.

Dan Fisher is the world's expert tusk decoder.

So what can you tell about the life of one of these animals by looking at its tusks?

One of the most basic things you can tell is its age.

You can count the years in the tusk.

This is the tip of the tusk of a male mastodon.

I've cut it here, and even on the rough-cut surface you can see

very clearly these years.

Each dark/light couplet represents one year of life.

-That's fantastic, just to be able to see that with the naked eye.

-Isn't it?

You can also tell things like the condition of the animal,

how it was responding to its environment, to the food that was available to it,

because good years, good times, when there's plenty of food, are represented by thicker rings.

Hard times are represented by thinner layers.

By analysing her tusks, Dan can tell when a mother was pregnant,

and even when she was suckling her baby.

Owosso is 13.

She's just had her first calf.

He will rely on her milk for at least two years.

What can you tell about Owosso's life?

Owosso's reproductive life began with a successful calving interval.

She had that fist calf, no problem,

but after that she lost calf after calf after calf,

a sequence of three, that died apparently as soon as they were born.

Owosso is feeding quietly.

She's just lost her third calf.

Is she a bad mother or a victim of her times?

To find out, I need to discover what was happening as the ice disappeared...

..and how it affected the Ice Age giants.

Grisly discoveries made in Hope Avenue in Tennessee may hold a clue.

Behind its finely clipped hedges and manicured lawns,

this immaculate neighbourhood hides a terrible secret.

Excavations for a new golf course beyond the gardens' edge

uncovered the dismembered remains of three mastodons.

And now a major archaeological dig is underway.

Alongside the bones, John Broster and Mike Waters

unearthed tell-tale signs of a new breed of predator.

-Yeah.

-..down at the Tennessee River. That was quarried for...

They had come to North America from Asia, around 15,000 years ago.

The first Americans.

There were around six or eight tools found with the mastodons.

One of the main ones is called a blade, and it's a long cutting tool

made out of flint and was probably used to cut and strip meat with.

Another tool called gravers, and they have these very sharp tips.

These points were created so that they could score bone with it

so they could split bone and turn the bones actually into tools.

It was a very important aspect of butchery,

was to get the bones as well as the meat.

So it seems that early Americans could skilfully cut up a mastodon carcass,

but were they actually killing them?

The team kept looking for clues.

When we were removing the ribs of the mastodon,

underneath the ribs was the tip of a bone projectile point, probably

the spear point used to kill the mastodon, so then we knew for sure

it had been killed versus actually scavenged, or something like this.

Hope Avenue isn't alone.

Another famous mastodon find from the same period, at the Manis

site, preserved the murder weapon, still embedded in its victim.

The mastodon rib was scanned.

The image reveals a spearhead

penetrating about two-and-a-half centimetres into the bone.

A 3-D reconstruction reveals that the tip broke off during impact.

It's irrefutable evidence that humans were hunting mastodons.

The bone projectile point that was found at the Manis site would have looked something like this.

Now, what we did is we took a sample

of the tip end of the bone point, ran DNA analysis on it

and the DNA analysis showed that it was made of mastodon bone.

So this indicated that at least one other mastodon had been

hunted by these people and that they'd taken the bone from the mastodon

and fashioned a bone projectile point from it.

Other sites in North America tell a similar story

of early humans hunting and butchering mastodons

and other Ice Age giants -

evidence that seems to implicate humans in the extinction of the megafauna.

It's tempting to think of those first Americans as rampaging

across the continent going on a massive killing spree.

But there were only small numbers of hunter-gatherers in this vast

landscape and we now know that the megafauna

survived for thousands of years after humans first arrived here.

So that leaves us looking

for another threat to the survival of the megafauna.

Around the same time as the animals went extinct,

there were cataclysmic changes to the environment.

Some of the greatest ice sheets the world has known were melting.

And as the world warmed up,

the thaw posed a great danger to the survivors of the Ice Age.

The evidence isn't hard to find.

It's scoured into the landscapes of northwest America.

And this has to be the best way to appreciate it.

Climbing this rock, I can almost feel the colossal forces that

surged through here 14,000 years ago.

This is certainly tougher than it looked from the bottom,

but I'm hoping that it's all going to be worth it

when I get to the top and I can look out at this view.

Before the break-up of the ice, there was no canyon here.

Just endlessly rolling hills, full of life.

But something demolished that idyllic landscape.

Wow, that's incredible! Just look at that.

This is Frenchman Coulee -

part of the Channeled Scablands of Washington State

and I've just climbed up one of the gigantic basalt columns which

forms the side of this huge gouge in the landscape,

which itself was created by phenomenally destructive natural forces.

Frenchman Coulee puzzled geologists for decades,

with its distinctive square profile, sheer cliffs and flat bottom.

With no sign of there ever having been a river here,

what could have carved out a canyon like this?

50 miles north, there are vast bowls at the feet of huge cliffs.

Signs of an enormous ancient waterfall,

over three times the size of Niagara.

This is evidence of an earth-shattering mega-flood.

So where did all the water come from?

15,000 years ago, to the east there stood

an incredible natural structure, more than a mile tall - an ice dam.

A glacier holding back a vast lake of meltwater

with a volume of 500 cubic miles.

This was Glacial Lake Missoula.

During the depths of the Ice Age, the dam held fast.

But as it got warmer, you can guess what happened.

The resulting flood was more than ten times the combined flow

of all the rivers in the world today.

The raging waters were 100 metres deep.

Racing along at 65 miles per hour,

the flood carried boulders, trees and the carcasses of any animals caught in its path.

On its way to the Pacific, it gouged out a gaping wound in the landscape,

through Idaho, Oregon and Washington.

And it wasn't just one flood.

Over 2,000 years, as the Ice Age relinquished its grip,

the ice repeatedly retreated and advanced.

With every melt, there was another flood...

..wreaking destruction and creating chaos.

Geologists believe there were over 100 mega-floods.

The devastation unleashed by the flood from Glacial Lake Missoula

was immense - the landscape still looks ruined today.

It was a catastrophic event on a massive scale

that spelled the end for any animals in its path.

Enormous meltwater floods like these occurred

right round the Northern Hemisphere.

But away from these scenes of destruction,

animals would have been safe.

As catastrophic as these events were, it seems

unlikely that it was mega-floods that killed off the Ice Age giants.

Whatever caused their extinction

must have been something on an even larger scale.

There is one possibility -

the wider impact of that huge shift in climate.

The Ice Age had created very different landscapes to what we see today.

On the dry grass plains of Siberia, woolly mammoths

and woolly rhinos are grazing.

Both are supremely adapted to the unique cold yet sunny Ice Age environment.

Their double-layered woolly coats keep them warm.

Both depend on a diet mainly consisting of grass,

and both require a vast amount of food every day...

..something that the sunny open steppes are perfectly able to provide.

Woolly mammoths and rhinoceroses didn't just live in a different age,

they evolved to thrive in a habitat which just doesn't exist anywhere today.

They were the kings of the mammoth steppe, a unique Ice Age environment,

a vast dry grassland which once stretched almost around the world.

From northern Europe, across Siberia, all the way to Alaska,

the dry, cold conditions of the Ice Age created this unique habitat.

A paradise for the megaherbivores.

Even in the depths of winter,

there was very little snow to cover the grass.

But as the Ice Age drew to a close, the world didn't simply get warmer.

The meltdown also brought with it wet weather.

Gone were the clear blue skies that had fostered

the spread of the great mammoth steppe,

and the gathering rain clouds and snow clouds

posed a great threat to the Ice Age megaherbivores.

It seems like a paradox.

But there's evidence that as the ice retreated,

it snowed more heavily than it had done for thousands of years.

The changing conditions allowed trees to return to the north.

The vast grasslands of the Ice Age gave way to forest and boggy tundra.

And in winter, everything disappeared under a lethal white blanket.

Without snow shoes, trudging through this deep snow is really difficult.

For a large animal it would be a struggle moving around

in this landscape, a struggle finding food,

and you'd never know where the next attack was going to come from.

You can just imagine how exhausting and nerve-racking that could be.

The deep snow is a particular problem for the woolly rhinoceros.

This young female is desperately searching for food.

She's exhausted.

Her short legs can't carry her any further.

The last evidence we have of woolly rhinoceros

dates to about 14,000 years ago in Siberia.

It seems they just couldn't cope with that dramatic climate change.

Their habitat shrank and finally disappeared

and when the steppe went, so did they.

Climate change now hit habitats right across the Northern Hemisphere,

but in quite different ways.

On my journey through Ice Age America,

I encountered the strangest mammal I had ever seen.

Today, its remains are found scattered in the Arizona desert.

How amazing,

to be one of the first people to see this ancient creature.

But the glyptodont wasn't a desert-loving animal.

It was a creature of the swamp.

During the Ice Age,

the vast American ice sheet diverted the rain south...

..turning desert into wetland,

and creating the ideal home for these mammals.

But during the thaw, the rains moved north,

turning the southern swamps into the deserts we see today...

..spelling the end for these mighty beasts.

Could climate change also explain the disappearance

of other great mammals of the Ice Age, such as mastodons?

Evidence is now emerging across the eastern United States.

In the Appalachian mountains of Virginia, palaeontologists

are unearthing bones -

the remains of mastodons that died during this period of most intense climate change.

-Just get the trowel and see if you can pop it out.

-OK.

What we have here is fossils from

the end of the Ice Age, here in Saltville.

We have mammoths, we have mastodons.

Right here behind me is a mastodon tusk that they are excavating.

We have a gravel layer that represents an old river bed,

and right above that are these clay deposits from an old lake bed as well.

So we get these two different time frames represented from the very end of the Ice Age.

The most valuable clues are these -

giant pieces of jaw, complete with teeth.

Mastodon's teeth were a key part of what made them such successful animals.

Inside their mouths are mountainous molars.

Superb munching tools, designed to mangle trees and grind up shrubs.

Mastodons were particularly fond of the spruce woodlands

that once dominated this part of America.

Mastodon teeth like these hold clues as to how they responded

when their food supply dwindled.

Trace elements within the teeth reveal where an animal foraged

during its lifetime.

As climate change kicked in, some mastodons

were migrating large distances to find their favourite food.

We're getting a glimpse of how mastodons' lives were disrupted

as their world changed.

But is there any evidence that they were under threat of extinction?

One thing that might help is these.

Surprising new research on bison in Kansas is revealing

the scale of the North American extinctions.

Remarkably, these bison have helped scientists to find

clues in the landscape, which reveal just how many giant mammals

once roamed these lands and precisely when they disappeared.

Bison are America's largest surviving species of Ice Age mammal

and here, they're protected in their favourite environment.

Kendra McLauchlan studies a microscopic fungus called Sporomiella,

which leaves its spores in the dung of large herbivores like bison.

Even though the dung rots away, the spores are extremely tough

and persist in the soil.

We can trap some of those spores

passively in our traps, and the idea is that we can measure

how many spores are in the traps

and get an idea of how many grazers are on the landscape.

The number of spores is a good indicator of the size

of animal populations.

The same fungus grew in the dung of Ice Age giants

and its spores are still found in soil dating from that time.

The spores reveal what happened to whole populations

of giant mammals at the end of the Ice Age.

Ice Age soil samples, from California to New York, were analysed.

They revealed that 18,000 years ago the soil was full of spores -

the giants were thriving.

But around 14,000 years ago the spores almost disappeared -

the sign of a massive population crash.

The big question is, was this crash caused by changes in climate and environment?

As well as containing spores,

the soil samples preserved a record of the vegetation.

But the results were a shock.

The vegetation did indeed change,

but after the crash of giant mammals.

So if climate change wasn't responsible for the crash...

..what was?

There's one more piece to this puzzle.

The last mastodons hold a dark secret.

Amongst their remains, Dan Fisher has identified

a number of bones which tell a harrowing story.

And this is another female mastodon.

So this is a female. It's one we call Eldridge,

and she has this very pronounced area of trauma to the front of her skull.

The skull has been broken

but the bony regrowth shows that she recovered from this assault.

And there's more evidence of violence.

These are parts of the skeleton that was recovered from a female known as Powers.

So this is all the same individual?

All the same individual. There's much more of her

but these are a few of her skeletal parts that display unusual sorts of injuries.

Her injuries are horrific.

Her neck vertebrae have been shattered.

But on this animal, the perpetrator has left its calling card.

In her shoulder blade, there's a deep puncture.

The shape of the hole tells Dan exactly what the weapon was -

a tusk!

I think this is evidence for a mastodon attacking another mastodon.

As unusual as that sounds, that's what the nature of the damage suggests.

What could possibly lead mastodons into attacking each other?

Mastodons' surviving cousins, modern elephants, may provide an answer.

This herd is made up of adult females and their young.

As the cows come into season, a mature dominant bull joins them for mating.

His presence suppresses the sexual behaviour of younger males.

Today, though, magnificent bull elephants are frequently targeted

by hunters and poachers for their huge tusks.

And this has a devastating impact - if dominant males are absent,

the younger, testosterone-pumped males go on the rampage,

often with tragic consequences for the breeding females.

The butchered skull of a mastodon male.

Dan believes that - as with elephants today - the large bulls were targeted.

So we've got some very disparate specimens here, Dan,

some showing evidence of injury mastodon-on-mastodon,

one here showing evidence of human interaction in the form of butchery.

Is there something which you think links all of this together?

I think there is. When we look early in the almost 3,000 years

of human/mastodon interaction that we have recorded in this region,

we see for instance,

a predominance of focusing of this hunting activity on mature adult males,

perhaps because they were solitary individuals and easier to surprise, easier to ambush.

That focusing of hunting activity on mature adult males

would have gradually depleted those from populations.

Dan's theory is that simply killing off the mature bulls

destabilized mastodon herds, helping to drive them to extinction.

Owosso has a new calf, a little female.

Two young bulls approach.

They are full of testosterone.

Owosso shields her baby, but lays herself open to attack.

A few weeks later, she's still limping,

and her calf is nowhere to be seen.

Owosso died when she was 29 years old,

middle-aged for a mastodon.

From her tusks, we know that three of her four calves

must have died close to birth.

Only one survived past weaning.

It's a story of tragic loss,

and Owosso was one of the last of her species.

So from your research, do you think we finally have an answer

as to why these animals went extinct?

What I see is a very slow-motion process,

a very long-term pattern of change.

I don't think humans doing this would have necessarily

even been aware of the long-term consequences of their actions.

Because for so long, the world was more or less as it had been -

for so long, there were the same animals,

and I'm sure they felt they depended on these animals, they could continue this hunting activity

that had been so successful for so long.

But what we can see from OUR perspective, is what happened finally.

And it was these very long-term consequences

of the hunting behaviour that in the end spelled extinction.

Owosso was just one animal

but her story illustrates the plight of her whole species.

It seems that the early Americans didn't have to slaughter

entire herds of mastodon to have an impact.

Instead, over thousands of years, there may have been just enough

hunting and scavenging by humans to be unsustainable,

to seal the fate of those giant mammals.

Megafauna were especially vulnerable to such hunting,

for a very particular reason.

Populations of huge, slow-breeding animals

just can't cope with even limited hunting over such a long period of time.

The effect of human predation was to spread like a ripple

through the populations of giant mammals.

Around the same time other giants, such as Columbian mammoths, also went extinct.

The disappearance of giant predators like the sabre-toothed cat though,

seems more puzzling - humans didn't hunt them.

But once the large herbivores were in trouble,

the future for anything that preyed on them was precarious.

This predator of the Ice Age is built to bring down large animals.

But she lacks the agility and endurance to hunt smaller, swifter prey.

With her main source of food gone, she'll struggle to feed her cubs.

It's a complicated story and undoubtedly some species

were affected by the changing climate more than others.

But now perhaps more than ever,

it seems that humans really were to blame for the extinction

of so many North American animals at the end of the last Ice Age.

BELLOWS

Though the true giants didn't make it, many other large animals did.

And their biology may explain why.

Unlike mammoths and mastodons, elk are prolific breeders.

Bison give birth to new calves each year, and can also migrate.

Adaptability combined with rapid reproduction

probably helped both species survive.

Another good survival strategy is to run away.

Pronghorn antelope are some of the fastest creatures on Earth.

Back in the Ice Age they had to run from giant predators.

Now they are on the lookout for an attack that will never come.

Perhaps their speed and agility kept enough of them safe

from the spears of early human hunters as well.

For the animals who preferred the cold,

there was one other means of escape.

As ice retreated north, they moved with it.

The Arctic became a refuge for species like musk oxen and reindeer.

And another animal that until recently survived in the north

was the most iconic giant of them all.

The woolly mammoth almost made it to the present day

and scientists have recently been investigating what could have been

their last stronghold.

Mammoth expert Dan Fisher joined an expedition to a remote island

off the north coast of Siberia in the Arctic Ocean - Wrangel Island.

80 miles north of the Siberian mainland,

this mystical island is rarely visited.

The Russian authorities give it maximum protection -

scientists are now amongst the very few humans allowed to land here.

Wrangel Island is an important place to come for the study of mammoths

because it's the place where the last populations survived.

The last mammoths before they finally went extinct lived here,

and we'd like to study them, to learn about the sorts of ecological stresses

that they were experiencing in their last millennia,

centuries - decades, even - if that's possible.

Wrangel is unique.

On the southern side of the island are some sheltered valleys

with their own special microclimate.

Here, a lost Ice Age habitat still survives.

The closest thing to the mammoth steppe,

where Ice Age animals still roam.

Woolly mammoths lived here so recently,

you can drive around and find their bones lying on the ground.

Well, but not so bad.

It's not long before Dan and the team start to uncover mammoth remains.

A magnificent tusk, untouched for thousands of years.

And another.

Dan can't help but start to read its record.

Winter-time, winter-time, winter-time.

This is how much it grew in one year.

Within a few days, the team finds the remains of 65 animals.

But it soon becomes apparent that something is different

about these mammoths.

Their bones are all small.

The last mammoths on the planet weren't giants.

In this, their final island refuge, they were becoming dwarves.

It's 2,000 BC.

The pyramids are being built in Egypt

and here on Wrangel Island,

a herd of woolly mammoths is migrating into the mountains.

They are retreating from a new predator,

one which poses a great danger to them.

Humans have recently arrived on the south coast of the island.

Though they died out thousands of years ago, some believe that these

may not be the last mammoths to live on Planet Earth.

Permafrost has preserved some incredible new specimens...

..complete with flesh, fur and even bone marrow.

And right now, scientists are hoping to extract their DNA.

Genetic technology may mean that it's possible to clone a woolly mammoth.

We could be on the brink of being able to resurrect Ice Age species.

Personally, I'd rather imagine them

as they were back in the Ice Age, roaming free on the steppes.

But in a way, and by accident,

humans have already saved many Ice Age species from extinction.

This is the Camargue in France, where herds of white horses roam free,

living as their ancestors did back in the Ice Age.

Horses evolved in North America, millions of years ago.

They were a global success story, spreading out right across the world.

Some even made it to Africa, where they became Zebras.

But as the Ice Age ended, horses suffered badly.

They died out completely in their ancestral home -

horses went extinct in America.

But in Europe and Asia they survived.

In a very few places, it's still possible to see why.

Animals like these are some of the most amazing

survivors of the Ice Age, not just because they survived

all those horrendous shifts in climate and the depredations,

but because they finally took an incredible step which would ensure their survival.

Every autumn, a very special event takes place here.

The brown foals, which until now have roamed free,

are about to take a massive step that will change their destiny.

They're rounded up to be separated from their white mothers,

ready to be tamed and trained as working horses.

These foals are about to be domesticated.

As our ancestors transformed themselves from hunter-gatherers

to farmers at the end of the last Ice Age,

horses made that leap with us.

It's almost as though they made a pact with us.

Suddenly their value is transformed from not being just prey.

They entered into a partnership

where they gave us their labour in exchange for food and care.

Horses are amongst a few species of large animals

which survived beyond the Ice Age, by teaming up with people.

Domesticated Ice Age animals helped us humans create the modern civilisations of today.

We're getting a glimpse into the wild past of this magnificent

animal that played such a huge part in the story of that

other great Ice Age survivor - us.

But as these magnificent horses thunder past, we can imagine,

for a moment, what their lost Ice Age world was like in all its majesty.

A time when the mighty Ice Age giants ruled the world.

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