Life on Earth

Why are you going that way?

You and I belong to the most widespread and dominant species of animal on earth.

We live on the ice caps at the pole and the tropical jungles at the Equator.

We've climbed the highest mountain and dived deep into the seas.

We've even left the earth and set foot on the moon.

And we're certainly the most numerous large animal.

There are something like 4,000 million of us today.

And we've reached this position with meteoric speed.

It's all happened within the last 2,000 years or so.

We seem to have broken loose from the restrictions

that have governed the activities and numbers of other animals.

Why should this be?

Well, the story starts back in Africa.

Ten million years ago, much of East and Central Africa was covered by wide open plains,

just as it is today, and living there were herds of grazing animals.

The ancestors of the antelope originally lived in the forest.

Other kinds of animals from there also ventured out into the open

in search of food.

Apes had come down from the trees.

Like the vervet monkeys of today,

those ancient apes probably stayed close to the fringes of the forest at first,

but regularly wandered out into the open to collect insects, seeds and other morsels.

The earliest of these ground-living apes were not much bigger than vervets,

but slowly, as they colonised the grasslands, they became better adapted to life in the open

and they grew somewhat in size.

About three million years ago, there were several species of them on the African plains,

and this is the reconstructed skull of one of them.

It has several characters which are an inheritance

from the tree-living, ape-like ancestors of this creature.

We can guess that its sense of smell, for example, wasn't very good.

The nasal cleft is quite small.

On the other hand, its vision was very good. It had two large, forward-facing eyes.

Its brain, while quite large, is only about half the size of that of modern man.

Although the teeth are missing in this specimen,

we know from others that they were remarkably even

and lacked the two long downward-pointing fangs which are sometimes present

and which lock the lower jaw in position.

So we can guess this animal could move its lower jaw from side to side

and was able to chew roots and nuts as well as eating flesh and maybe fruit.

Their fossilised bones are very rare.

We still don't know how many kinds there were or how they were related.

But on one thing, all who've studied their remains are agreed.

Those ancient apes included the ancestors of mankind.

They can be called, in fact, apemen.

And grasslands like these must have been the cradle of humanity.

Out on the grasslands, the talents the apemen's ancestors developed to cope with life in the trees

were put to other purposes.

Hands, once used for gripping branches,

were not much use for burrowing or tearing flesh.

But as time passed, they became more precise and dexterous in their grip

than any other primate's, and very like our own.

And these enabled the apemen to pluck not only leaves and fruit

but also to gather relatively fiddly morsels: nuts, seeds and insects.

The apemen were still quite small and largely defenceless.

This was a serious handicap,

for life on the open plain was dangerous.

As well as the harmless herds, there were hunters around.

The only way of escaping such enemies

was either to run fast, which the apemen weren't very good at,

or to climb a tree, of which there were not many.

So it obviously was of the greatest importance to get the earliest possible warning of danger.

Their ancestors' life in the trees led to a reduction in their sense of smell

but extremely good vision.

So the apemen must have reared up to get a good view of their surroundings.

And the vervets, faced with a similar problem, adopt just the same solution.

It's unlikely the apemen stood erect as a way of increasing speed,

for running on four feet is a much swifter way of getting around.

A vervet can outpace any two-legged primate.

But if you habitually rear on your hind legs, you can use hands for other things,

and one modern ape, the chimpanzee, does just that.

Chimps are the only animals that defend themselves with weapons like this.

There's every reason to suppose those early apemen could throw sticks and stones

just as modern chimps can.

Indeed, they would be in need of every form of defence they could get

because their teeth were small and they had no claws.

So, if threatened by a predator, they would pick up a stick

to try and defend themselves out on these African plains, as indeed I would.

And, what's more, with this in their hands,

they would stand some chance of driving off a predator from its kill

in order to claim the meat for themselves.

And eating meat has a lot to be said for it.

Getting all your sustenance from leaves is laborious and time-consuming.

They have comparatively little nourishment in proportion to their bulk.

So zebras are compelled to spend nearly half of their days grazing

in order to get all the food that they require.

The flesh-eaters, on the other hand, have a much lazier life.

Meat is so nourishing that lions only need to eat every two days or so,

and then only for about half an hour.

Doubtless, leisure had its appeal to the apemen too.

Whereas lions simply sleep, maybe the inquisitive apemen

used their spare time to socialise, to play, to create.

A kill on the plains, no matter who makes it, attracts all kinds of flesh-eaters.

A whole pride of lions may find more than they need in a single zebra carcass.

One way or another, everything is consumed,

even the tail.

And when the biggest and most powerful have taken all they want,

there are plenty of scavengers to clear up the remains.

Well, I only had vultures to deal with that time, and I didn't even need a stick.

If there'd been hyenas, I guess I would have needed it, but I could have got rid of them.

And maybe if I'd had a few companions, I could have shifted a pride of lions.

But having got here, how could an apeman with small teeth

manage to get into a carcass like this?

Well, he could take a stone and...

And it's already cutting, and this is really a quite ordinary stone,

but one that has just been chipped here on either side to produce a cutting edge.

And just such stones have been found with the skeletons of the earliest apemen

of about two million years ago.

So, with a chipped stone, a stick and a pair of manipulative hands,

the apemen could have survived out on the plains as hunters.

This state of affairs lasted for several million years.

Slowly, the apeman became better at walking.

His legs lengthened to increase his stride,

and he grew to a height of about five and a half feet.

To mark his new stance, science has given him a new name.

Homo erectus : "upright man".

The foot acquired an arch to give a spring to his stride,

and his first toe grew to take the thrust of the foot.

The name "man" here has no sexist implications.

It's the scientific name for the genus to which these women, children and men belonged.

And a million years ago, they spread widely over the African plain.

Their fossilised remains are very rare,

for bodies lying out in the open are eaten by scavengers

and bones weather into dust.

But stone is much more durable, and in some places, the tools made by upright man

still litter the ground in huge numbers.

From them, we can see he was using his dexterous hands with increasing skill.

Almost every one of these stones, which have washed out from that bank over there,

have been worked by man in one way or another.

Some of them are far more elaborate than anything produced by the apemen.

Like this one, for example. Beautifully chipped.

This was probably a hand axe, used for digging up roots.

And then there are cleavers like this with a flat cutting edge.

They may have been used in butchering animals: cutting flesh and stripping skin.

These aren't the only tools.

This rounded stone has not been rounded by a stream, which would produce smooth surfaces,

but carefully chipped,

and it's probable that these rounded stones, of which huge numbers have been found here,

were used either for pounding vegetables of some kind

or as weapons.

And the reason we suppose they were used as weapons

is because also on this site have been found great numbers of animal bones.

This and most of the bones found on this site belonged to an extinct baboon

that was even bigger than the living baboon.

Most of these bones, like this fragment from the lower jaw, there are the teeth,

have actually been split open in order to get out the marrow.

This remarkable site provides a lot of evidence about the nature of upright man.

The stone from which tools are made, and there's around a ton of them,

doesn't occur naturally within 30km of here.

So all these stones must have been brought here deliberately by the people,

and that suggests foresight and planning.

For another thing, the baboon they hunted must have been a ferocious animal.

I don't imagine there are many men who would fancy the idea of going out

and trying to hunt a baboon armed with a few cobblestones.

And yet the extinct baboon was even bigger and presumably more ferocious.

So it seems likely that the early people hunted in teams.

Teamwork, foresight, planning.

That argues that they had some considerable skill in communicating among themselves.

Letting others know how you feel is a basic part of communication.

No creature in the world does so more eloquently than man,

and no organ is more visually expressive than his face.

Even in repose, the human face sends a message, and one we tend to take for granted.

Each face proclaims individual identity.

In teams, recognition of other members is of great importance.

A hunting dog in a pack proclaims its identity by its own smell.

Primates, with their reduced sense of smell but very acute vision,

do it by the infinite variety of their faces.

We have more separate muscles in our faces than any other animal.

So we can move it in a variety of ways no other animal can equal.

And not only convey mood but send precise signals.

By the expression on our face, we can call people and send them away,

ask questions and return answers without a word being spoken.

Eyebrows are particularly eloquent.

We can use them as question marks and as greetings.

But are our gestures recent conventions we've learned from one another?

Or are some inherited from our remote ancestors?

Did upright man formulate his hunting plans by pointing and nodding

and express his delight with a smile?

If we could meet modern men who have never been in contact with our world

and discover whether we had signals in common,

then we might find clues to the answer.

Ten years ago, I had the chance to do just that.

A patrol led by an Australian government officer

was going to cross one of the last patches of unexplored country in central New Guinea.

And I went with it.

The tribesmen who came with us said there were people living in these forests.

They saw them rarely and knew only one word of their language, their name.

Biame.

But no European had ever seen them.

Biame!

We walked for about a week without meeting anyone, and then one morning

the Biame quietly appeared.

Biame!

With gestures, they seemed to be saying we were in the middle of their territory.

They nodded in agreement, they smiled to give reassurance.

We wanted them to bring down other members of their group

and tried to convey this complicated message with gestures.

Although our two societies had never come into contact before this moment,

it seemed that many of our gestures did have the same meaning.

These nods and smiles, frowns and headshakes

were surely not mere conventions but deep in us.