Age of Big Cats

One and a half million years ago,

much of the Earth's land was covered by short grass steps.

It was the Pleistocene age.

Throughout this tumultuous time,

the Earth was being pummelled by repeated ice ages.

With each ice age, forests retreated, and grasslands spread.

Huge herds of prey were laid bare for a host of hunters.

The cat-like sabre-toothed Megantereon,

with its enormous fangs, lay in ambush.

Spotted hyenas and ice aged giant hyenas,

tested the herds for signs of weakness.

Top of the food chain was the dagger-toothed Homotherium,

pack-hunting killers that were rampant across the world,

from Africa to the Americas.

They were on the lookout for something big, really big.

Like a young steppe mammoth.

This was the age of the sabretooths.

These were the world's top land predators.

But things were changing.

New forces threatened the old order,

with skills the planet had never seen before.

The big cats.

From this point in time, they rose to power,

ending millions of years of world domination,

by terrifying, now extinct, predators.

Every species of these sabretooths vanished,

while almost all the big cats survived.

Why them?

What's their story?

In this episode, we go back to when the big cats

were just beginning their ascent,

to discover how the cheetah became so fast,

why the elusive snow leopard takes such incredible risks,

and how the jaguar travelled to the ends of the Earth.

Big cats were on the rise.

Among the earliest to appear were cheetahs.

They lacked the enormous fangs of the sabretooths,

and didn't have the bone-crushing jaws of the hyenas.

But like most cats, had something the others didn't,

much more of a special kind of extra powerful muscle,

known as very fast-twitch muscle.

When this is combined with the cheetah's light-weight frame,

it can deliver record-breaking speed.

It could outrun all the other predators,

but more importantly, its prey.

As far as we can tell, cheetahs are the fastest land mammals

that have ever been.

But their gift came at a price.

They have no stamina.

Here, in Asia, during the Ice Age,

these grasslands stretched for thousands of miles

in every direction.

Prey animals roamed in their millions

over the steppes, following the best grazing.

This was the habitat the cheetah evolved to exploit.

Today, the cheetahs of Asia are practically extinct.

Luckily, in Africa, about 7,000 of these elegant wanderers

still survive.

By observing modern cheetahs, we can learn more

about how they found their place in the ancient world,

and why their existence is so fragile.

Cheetahs need open plains and, just as in the Ice Age,

here there are still elephants

that keep the plains free of trees,

removing saplings as they emerge from the grass.

The steps of the Serengeti are among the few places

left on Earth where there are wide open spaces

packed with potential prey.

And today, as in the past, there's no shortage of predators

that could easily overpower a cheetah.

And vultures still crowd the numerous kills

of the numerous predators.

Most of the grazers stay as far from cover

as they possibly can,

so they can see if trouble is coming their way.

Any sign of a lurking killer, the herds generally run,

or display their extreme fitness,

so the cheetah has a problem,

which it solves in a unique way.

Near the equator, the mid-day sun roasts the ground.

With no shade, it's 40 degrees.

Most hunters are much less active at this time of day.

The fragile cheetah uses this moment of quiet

to its advantage.

Its super-sharp daylight vision

enables it to see far off tiny details,

like a small group of gazelles grazing a kilometre away.

From this distance, the gazelle's stamina

could easily beat a cheetah.

So, this young male will need every ounce of patience

to get near enough for a strike.

He uses the heat haze as camouflage.

From the gazelle's low position,

only the upper part of the cheetah is visible.

It can often take an hour for a cheetah to get within range.

Ideally, less than 100 metres.

His super strength muscle kicks in.

In a few seconds, he accelerates

to almost 100 kilometres an hour.

The cat has covered 50 metres before the gazelle

hears its paws hitting the ground.

By the time the gazelle has reached its own full speed,

the gap is down to five metres.

In slow motion, it looks effortless,

but the cheetah is now using much of his strength

just to push through the air.

He pulls his legs tight below his body to reduce drag.

Now he is practically flying, getting lift from every bound.

But he needs to be careful,

there is a time limit on his run.

The gazelle's tiny hooves dig into the ground

to make extremely sharp turns.

The cheetah's extended claws grab hold of the earth,

to match the gazelle turn for turn.

He is burning energy at a prodigious rate,

and only has seconds left before his reserves are exhausted.

Very fast-twitch muscle delivers extra power

but only for a short time.

This is the kind of knife edge that drives evolution.

The gazelle has increased his chances

of passing on his genes,

while the cheetah will have to search for a meal

that is not quite so fast.

This mother and her almost full-grown cub

have found themselves in an area with no gazelles,

and the only prey on offer are wildebeest.

Compared to a gazelle,

wildebeest are quite slow and less agile.

This ought to be easy.

But she fails to trip her victim,

to use its own momentum to bring it down.

Luckily, her cub is here to help.

The sabretooths had weight and powerful forelimbs

to stop their prey.

The light-weight cheetah has neither.

They are working at the very limit of their abilities,

only acting together do they have any chance

of pulling the wildebeest to the ground.

While the cheetah's body weight is reduced for speed,

their typical cat-like short faces

give them a powerful bite,

strong enough to silence the victim

and to cut through skin quickly, which is just as well.

Vultures are already circling.

They can spot the tell-tale dust trail from 3,000 metres up.

The cheetahs will have to eat as fast as they can

because dropping vultures are a sign that hyenas use

to find free food,

as they were back in the Pleistocene.

As the first hyena arrives, the cheetahs move on,

having put away as much as they can.

Of all the cats, the cheetah is the only one

that is a true nomad.

As long as they stay on the move, they can survive

among much more powerful predators.

In the Pleistocene, these amazing cats could walk,

unhindered, across continents, and they did.

From the southern tip of Africa, to the Russian far-east.

But today, they have lost almost all of their range,

and in many areas, their continued existence is in doubt.

As cheetahs disappeared from Asia, their fate in Africa

is following the same trajectory.

Extensive steppe grasslands like the Serengeti

are becoming increasingly rare.

In the past, all over the world, the spread of grasslands

had favoured the running hunters, like Homotherium,

hyenas, and now, the cheetahs.

They were so successful, they evolved into two kinds,

the standard cheetah and the 90-kilo giant cheetah,

big enough to go after horses.

This was a dangerous place to be unless you were fully fit.

As a result, some of the prey animals moved off the plains

onto rocky country, where the runners couldn't catch them.

For a period, the mountain grazers

had the cliffs all to themselves,

and evolved into many new forms.

These were to be the bait that lured

a new predator into the mountains,

one that bore a remarkable similarity to a big cat,

that still survives here today.

The ice ages may be over,

but the rocky peaks throughout Central Asia

are some of the harshest places on Earth.

Even today, winter temperatures can drop to as low as -40.

This is the world the snow leopard inherited.

To survive in these desolate places,

snow leopards must have evolved some special abilities.

We have no evidence that the sabretooths

ever adapted to live in mountains.

The snow leopard must have been a real pioneer.

Firstly, it had to invent its own super warm fleece,

a coat so thick,

it could even cushion the cat against accidents.

It carries a huge tail, weighted with fat,

and massive, fury paws.

Adaptation to match its quarry for agility and grip.

This cat is practically the opposite of a cheetah,

retiring and extremely tough.

Yet, like the cheetah, snow leopards share the same kind of

high-power, very fast-twitch muscle,