Charles Darwin and the Tree of Life

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DAVID ATTENBOROUGH: Our Earth

is the only known planet

that sustains life.

And it does so in abundance.

I have been fortunate enough

over the years

to travel to some of the most

extraordinary and remote places on Earth

to find and film animals.

This is the biggest flower in the world.

The blue whale!

It's the biggest creature

that exists on the planet!

ATTENBOROUGH:
The sheer number

and variety of animals and plants

is astonishing.

Estimates of the number

of different species

vary from six million

to a hundred million.

Nobody knows exactly how many different

kinds of animals there are here.

Wherever you look, there's life.

There are often a multitude

of variations on a single pattern.

Nearly 200 different kinds of monkeys,

for example.

And 315 humming birds,

nearly a thousand bats.

And beetles, at least 350 thousand

species of them.

Not to mention a quarter of a million

different kinds of flowering plants.

The variety is astounding.

(CHUCKLES)

(CHIRPING)

Even in this one small English woodland,

you might see four or five

different kinds of finches.

Why should there be

such a dazzling variety?

And how can we make sense of

such a huge range of living organisms?

Two hundred years ago,

a man was born who was to explain

this astonishing diversity of life.

In doing so, he revolutionised the way

in which we see the world

and our place in it.

His name was Charles Darwin.

This book, The Holy Bible, explains how

this wonderful diversity came about.

On the third day, after the creation

of the world, God created plants.

On the fifth day, fish and birds,

and then, on the sixth day,

mammals and finally, man.

That explanation

was believed, literally,

by, pretty well, the whole of

Western Europe for the best part

of 2,000 years.

And generations of painters

pictured it for the faithful.

This version was painted in Italy

in the 16th century.

Here is God in the Garden of Eden,

which is now filled

with all kinds of animals.

Here he is pulling Adam

out of the Earth

and here creating the first woman

by putting Adam to sleep,

and then taking one of his ribs

and extracting Eve from his side.

And she comes out assisted

by two angels.

And when God had finished,

he said to Adam and Eve,

"Be fruitful and multiply

and replenish the Earth and subdue it,

"and have dominion over the fish of

the sea and over the fowl of the air,

"and over every living thing

that moveth upon the Earth".

That made it clear

that according to the Bible

humanity could exploit the natural world

as they wished.

This view of mankind's superiority

still stood when, in 1831,

a British surveying ship, the Beagle,

set off on a voyage around the world.

On board, as a companion to the captain,

was the 22-year-old Charles Darwin.

They crossed the Atlantic and

made landfall on the coast of Brazil.

There, the sheer abundance

of tropical nature

astonishes the newcomer,

as I discovered when I retraced

Darwin's steps, 30 years ago,

for a television series

about the diversity of nature.

Darwin, as a boy, had been

a fanatical collector of insects.

And here, he was enthralled

almost to the point of ecstasy.

In one day, in a small area,

he discovered

As he wrote in his journal,

"It's enough to disturb the composure

"of the entomologist's mind

to contemplate the future dimension

"of a complete catalogue".

They went south, rounded Cape Horn,

and so reached the Pacific.

And then, in September 1835,

after they had been away

for almost four years,

they landed on the little-known islands

of the Galapagos.

Here, they found creatures that existed

nowhere else in the world.

Cormorants that had lost

the power of flight.

Lizards that swam out through the surf

to graze on the bottom of the sea.

Darwin, who had studied botany

and geology at Cambridge university,

collected specimens

of the animals and plants.

And as usual, when he went ashore

to investigate,

described what he found in his journal.

"My servant and self were landed

a few miles to the northeast,

"in order that I might examine

the district mentioned above

"as resembling chimneys".

Volcanic chimneys, presumably.

"The comparison would have been

more exact if I had said

"the iron furnaces near Wolverhampton".

(CHUCKLES)

The British resident in the Galapagos

claimed that he knew

from the shape

of a giant tortoise's shell

which island it had come from.

If it had a rounded front,

it came from a well-watered island

where it fed on lush ground plants.

Whereas one from a drier island

had a peak at the front,

which enabled it to reach up

to higher vegetation.

Were these tortoises,

each on their separate islands,

different species?

And if so, was each one

a separate act of divine creation?

The differences that Darwin had noticed

amongst these Galapagos animals,

were, of course, all tiny.

But if they could develop, wasn't it

possible that over the thousands

or millions of years, a whole series

of such differences might add up

to one revolutionary change?

On his voyage home, Darwin

had time to ponder on these things.

Could it be that species

were not fixed for all time,

but could, in fact, slowly change?

On his return,

he sorted out his specimens

and sent them off to relevant experts

so that each

could be identified and classified.

Most of the mammal bones and fossils

he sent to Richard Owen.

Owen was one of the most brilliant

zoologists of his time.

He was the first to recognise dinosaurs,

and indeed had invented their very name.

And he would later become

the creator and first director

of the Natural History Museum in London.

Many of the specimens

that Darwin collected

are still preserved and treasured here

among the 70 million other specimens

housed in the museum that Owen founded.

And here is one of them.

It's obviously the lower jaw

of some great animal,

and when Darwin discovered it, it had

bits of skin and hair attached to it

so at first it was thought to be the

remains of some unknown living species.

But now we know that it is a species

that was extinct for some 10,000 years,

a giant ground sloth.

Owen examined it in great detail

and eventually described it and

gave it the name of Mylodon darwinii

in honour of its discoverer.

But that mutual respect

between two great men of science

was not to last.

Soon after his return from his voyage,

Darwin made his home here in Down House

in Kent.

Here, he wrote an account of his travels

and worked on detailed

scientific treatises

about corals and barnacles and the

geology and fossils of South America.

But he also pondered deeply

on what he had seen in the Galapagos

and elsewhere.

Maybe species were not fixed.

Every day, he took a walk

in this small spinney

that he had planted

at the end of his garden.

And it was here that he came to ponder

on the problems of natural history

including that mystery of mysteries:

how could one species turn into another?

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