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The theory of evolution by natural selection
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was put forward in the 1850s
independently by two men.
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One was Charles Darwin,
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who lived in this house,
in the village of Downe in Kent.
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The other was Alfred Russel Wallace.
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Both men had some scientific background,
of course.
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But at heart, both men were naturalists.
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(Birdsong)
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The fact is that there are two traditions
of explanation
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that march side by side in the ascent of man.
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One is the analysis of the physical structure
of the world.
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The other is the study of the processes of life:
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Their delicacy, their diversity,
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the wavering cycles from life to death
in the individual and in the species.
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And these traditions do not come together
until the theory of evolution.
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Because, until then, there is a paradox
which cannot be resolved,
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which cannot be begun, about life.
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We see it about us in the birds, the trees,
the grass, the snails - in every living thing.
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The manifestations of life,
its expressions, its forms,
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are so diverse that they must contain
a large element of the accidental.
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And yet, the nature of life is so uniform
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that it must be constrained by many necessities.
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So it's not surprising that biology,
as we understand it,
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begins with naturalists
in the 18th and 19th centuries.
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Observers of the countryside,
birdwatchers, clergymen,
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doctors, gentlemen of leisure in country houses -
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I'm tempted to say
gentlemen in Victorian England.
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Because it cannot be an accident
that the theory of evolution is conceived twice
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by two men living at the same time,
in the same culture -
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the culture of Queen Victoria in England.
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Charles Darwin was in his early twenties
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when the admiralty was about to send out
a survey ship
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to map the coast of South America,
called the Beagle.
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And he was offered the post of Naturalist.
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The five years that he spent on the ship
transformed him.
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He had been a sympathetic, subtle observer
of birds, flowers...
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life in his own countryside.
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But South America exploded all that for him.
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He came home convinced
that species are taken in different directions
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when they are isolated from one another.
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Species are not immutable.
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But when he came back,
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he could not think of any mechanism
that drove them apart.
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That was in 1836.
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At that time, Wallace was a boy in his teens.
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He was born in 1823.
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That makes him 14 years younger than Darwin.
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WALLACE:
"Had my father been a moderately rich man,
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my whole life would have been
differently shaped.
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And though I should, no doubt,
have given some attention to science,
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it seems very unlikely
that I should have ever undertaken a journey
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to the almost unknown forests of the Amazon,
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in order to observe nature
and make a living by collecting."
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So Wallace wrote about his early life,
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when he had had to find a way
to earn his own living in the English provinces.
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He took up the profession of land surveying,
which did not require a university education.
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It was an open -air life, and Wallace became
interested in plants and insects.
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When he was working at Leicester,
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he met a man with the same interests,
who was rather better educated.
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[Skipped item nr. 60]
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~ ERIK SATIE: Embryons Desseches
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His new friend astonished Wallace
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by telling him that he had collected
several hundred different species of beetles
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in the neighbourhood of Leicester,
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and that there were more to be discovered.
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It was a revelation to Wallace,
and it shaped his life and his friend's.
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The friend was Henry Bates,
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who later did famous work
on mimicry among insects.
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Meanwhile, the young men had to make a living.
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Fortunately,
it was a good time for a land surveyor,
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because the railway adventurers of the 1840s
needed him.
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Wallace was employed
to survey a possible route
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for a line in the Neath Valley in south Wales.
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Wallace was a conscientious technician,
as Victorians were.
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But he suspected, rightly,
that he was only a pawn in a power game.
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Most of the surveys were only
meant to establish a claim
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against some other railway robber baron.
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Wallace calculated that only a tenth of the lines
surveyed that year were ever built.
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(Train whistle)
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The Welsh countryside was a delight
to the Sunday naturalist.
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Now Wallace observed and collected
for himself,
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with a growing excitement
in the variety of nature
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that affectionately remained in his memory
all his life.
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~ Monastery Bells
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WALLACE: "Even when we were busy,
I had Sundays perfectly free,
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and used them to take long walks
over the mountains with my collecting box,
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which I brought home full of treasures.
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At such times, I experienced the joy
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which every discovery of a new form of life
gives to the lover of nature.
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Almost equal to those raptures
which I afterwards felt
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at every capture of new butterflies
on the Amazon."
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He found a cave on one of his weekends
where the river ran underground,
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and decided then and there to camp overnight.
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It's as if unconsciously he was already
preparing himself for life in the wild.
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WALLACE:
"I wanted for once to try sleeping out of doors,
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with no shelter or bed but what nature provided.
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I think I had determined purposely
to make no preparation,
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but to camp out just as if I had come accidentally
to the place in an unknown country,
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and had been compelled to sleep there."
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In fact, he hardly slept at all.
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When he was 25,
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Wallace decided to become a full-time naturalist.
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It's an odd Victorian profession.
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It meant that he would have to keep himself
by collecting specimens in foreign parts,
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to sell to museums and collectors in England.
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And Bates would come with him.
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So, the two of them set off in 1848
with a hundred pounds between them.
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They sailed to South America
and then 1,000 miles up the Amazon
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to the city of Manaos,
where the Amazon is joined by the Rio Negro.
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(Squawking)
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Wallace had never been further than Wales,
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but he was not overawed by the exotic.
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From the moment of arrival,
his comments were firm and self-assured.
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For example, on the subject of vultures...
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WALLACE:
"The common black vultures were abundant,
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but were rather put to it for food
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being obliged to eat palm fruits in the forest,
where they could find nothing else.
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I am convinced, from repeated observations,
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that the vultures depend entirely on sight,
and not at all on smell, in seeking out their food."
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The friends separated at Manaos
and Wallace set off up the Rio Negro.
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He was looking for places that had not been
much explored by earlier naturalists.
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If he was going to make a living by collecting,
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he needed to find specimens of unknown
or, at least, of rare species.
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(Birdsong)
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The river was swollen with rain,
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so that Wallace and his Indians were able
to take the canoe right into the forest.
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The trees hung low over the water.
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Wallace, for once, was awed by the gloom.
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But he was also elated
by the variety in the forest.
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WALLACE: "What we may fairly allow
of tropical vegetation
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is that there is a much greater number
of species and a greater variety of forms
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than in the temperate zones.
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Perhaps no country in the world contains such
an amount of vegetable matter on its surface
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as the valley of the Amazon.
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Its entire extent,
with the exception of some very small portions,
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is covered with one dense and lofty
primeval forest,
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the most extensive and unbroken
which exists upon the earth."
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~ WAGNER: Das Rheingold
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"The whole glory of these forests could
only be seen by sailing gently in a balloon
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over the undulating, flowery surface above.
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Such a treat is, perhaps, reserved
for a traveller of a future age."
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He was excited when, for the first time,
he went into a native Indian village.
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WALLACE: "The most unexpected
sensation of surprise and delight
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was my first meeting and living
with a man in a state of nature,
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with absolute uncontaminated savages.
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They were all going about their own work
or pleasure,
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which had nothing to do with white men
or their ways.
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They walked with the free step of
the independent forest dweller,
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and paid no attention whatever to us,
mere strangers of an alien race.
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In every detail, they were original
and self-sustaining,
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as are the wild animals of the forest.
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Absolutely independent of civilisation.
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And who could, and did,
live their own lives in their own way,
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as they had done for countless generations,
before America was discovered."
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~ SAINT-SAENS: Carnival Of The Animals
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It turned out that the Indians were not fierce,
but helpful.
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Wallace drew them into the business of
collecting specimens.
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WALLACE:
"During the time I remained here, 40 days,
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I procured at least 40 species of butterflies
quite new to me,
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besides a considerable collection
of other orders.
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One day, I had brought me
a curious little alligator of a rare species,
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which I skinned and stuffed,
much to the amusement of the Indians,
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half a dozen of whom
gazed intently at the operation."
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Like Darwin, Wallace was struck by
the difference between neighbouring species.
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And, like Darwin, he began to wonder
how they had come to develop so differently.
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WALLACE: "There is no part of natural history
more interesting or instructive
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than the study of the geographical distribution
of animals.
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Places not more than 50 or 100 miles apart
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often have species of insects and birds
at the one which are not found at the other.
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There must be some boundary
which determines the range of each species,
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some external peculiarity to mark the line
which each one does not pass."
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Wallace is as acute an observer of men
as of nature.
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In an age in which Victorians
called the people of the Amazon "savages,"
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he has a rare sympathy with their culture.
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He understands what language, what invention,
what custom means to them.
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He is perhaps the first person to seize the fact
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that the distance between that civilisation
and ours is much shorter than we think.
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WALLACE: Natural selection could
only have indulged savage man
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with a brain a few degrees superior
to that of an ape,
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whereas he actually possesses one
very little inferior to that of a philosopher.
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With our advent,
there had come into existence a being
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in whom the subtle force we term "mind"
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became of far more importance
than mere bodily structure."
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At this point,
Wallace's journal breaks into poetry.
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Well, into verse.
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WALLACE: "There is an Indian village;
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all around the dark eternal boundless forest
spreads its varied foliage.
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Here I dwelt a while.
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The one white man
among perhaps 200 living souls.
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Each day, some labour calls them.
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Now they go to fell the forest's pride,
or in canoe,
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with hook and spear and arrow,
to catch fish.
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A palm tree's spreading leaves
supply a thatch,
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impervious to the winter's storms and rain.
195
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The women dig the mandioca root,
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and with much labour, make of it their bread.
197
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And all each morn and eve wash in the stream.
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And sport like mermaids in the sparkling wave.
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The children of small growth are naked
and the boys and men wear but a narrow cloth.
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How I delight to see those naked boys!
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Their well-formed limbs, their bright, smooth,
red-brown skin,
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and every motion full of grace and health.
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And as they run and race and shout and leap,
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or swim and dive beneath the rapid stream,
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I pity English boys,
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00:19:17,360 --> 00:19:21,592
their active limbs cramped and confined
in tightly-fitting clothes.
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00:19:22,760 --> 00:19:25,877
But how much more I pity English maids,
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their waist and chest and bosom all confined
by that vile, torturing instrument called 'stays."'
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(Plays traditional tune)
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"I'd be an Indian here and live content
to fish and hunt, and paddle my canoe,
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00:19:49,480 --> 00:19:54,634
and see my children grow like young, wild fawns
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00:19:54,720 --> 00:19:58,076
in health of body and in peace of mind.
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Rich without wealth,
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00:20:01,280 --> 00:20:03,555
and happy without gold."
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The sympathy is different from the feelings
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00:20:11,920 --> 00:20:15,071
that South American Indians aroused
in Charles Darwin.
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When Darwin met the natives of
Tierra del Fuego, he was horrified.
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That's clear from his own words
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and from the drawings
in his book on the voyage of the Beagle.
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No doubt the ferocious climate had an influence
on the custom of the Fuegians,
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00:20:33,720 --> 00:20:41,035
but 19th-century photographs show that they did
not look as beastly as they seemed to Darwin.
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Wallace spent four years in the Amazon basin,
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then he packed his collections
and started home.
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WALLACE:
"The fever and ague now attacked me again
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and I have passed several days
very uncomfortably.
226
00:21:01,720 --> 00:21:05,156
And to attend to my numerous birds and animals
was a great annoyance,
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00:21:05,240 --> 00:21:07,310
owing to the crowded state of the canoe
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and the impossibility of properly cleaning them
during the rain.
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Some died almost every day.
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And I often wished
I had had nothing whatever to do with them.
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Though, having once taken them in hand,
I determined to persevere.
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00:21:27,680 --> 00:21:31,719
Out of 100 live animals
which I had purchased or had had given to me,
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00:21:31,800 --> 00:21:34,758
there now only remain 34."
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00:21:36,000 --> 00:21:38,798
The voyage went badly from the start.
235
00:21:38,880 --> 00:21:42,350
Wallace was always an unlucky man.
236
00:21:43,400 --> 00:21:45,914
WALLACE:
"On the 10th June, we left Manaos,
237
00:21:46,000 --> 00:21:49,197
commencing our voyage
very unfortunately for me.
238
00:21:49,280 --> 00:21:52,875
For, on going on board,
after bidding adieu to my friends,
239
00:21:52,960 --> 00:21:54,916
I missed my toucan,
240
00:21:55,000 --> 00:22:00,279
which had, no doubt, flown overboard and,
not being noticed by anyone, was drowned."
241
00:22:00,360 --> 00:22:04,114
His choice of a ship was most unlucky.
242
00:22:04,200 --> 00:22:07,875
She was carrying an inflammable cargo
of resin.
243
00:22:09,080 --> 00:22:14,393
Three weeks out, on August 6th, 1852,
the ship caught fire.
244
00:22:19,680 --> 00:22:23,593
WALLACE: "I went down into the cabin,
now suffocatingly hot and full of smoke,
245
00:22:23,680 --> 00:22:25,636
to see what was worth saving.
246
00:22:25,720 --> 00:22:29,759
I got my watch and a small tin box
containing some shirts
247
00:22:29,840 --> 00:22:33,196
and a couple of old notebooks
with some drawings of plants and animals,
248
00:22:33,280 --> 00:22:35,236
and scrambled up with them on deck.
249
00:22:35,320 --> 00:22:40,519
Many clothes and a large portfolio of drawings
and sketches remained in my berth,
250
00:22:40,600 --> 00:22:43,512
but I did not care to venture down again
251
00:22:43,600 --> 00:22:49,596
and, in fact, felt a kind of apathy about saving
anything that I can now hardly account for.
252
00:22:58,200 --> 00:23:03,593
The captain at length ordered all into the boats
and was himself the last to leave the vessel.
253
00:23:10,440 --> 00:23:14,513
With what pleasure had I looked upon
every rare and curious insect
254
00:23:14,600 --> 00:23:16,556
I had added to my collection.
255
00:23:16,640 --> 00:23:19,712
How many times,
when almost overcome by the ague,
256
00:23:19,800 --> 00:23:24,749
had I crawled into the forest and been rewarded
with some unknown and beautiful species?
257
00:23:24,840 --> 00:23:29,550
How many places, which no European foot
but my own had trodden,
258
00:23:29,640 --> 00:23:32,757
would have been recalled to my memory
by the rare birds and insects
259
00:23:32,840 --> 00:23:34,637
they had furnished to my collection?
260
00:23:34,720 --> 00:23:36,676
And now...
261
00:23:37,800 --> 00:23:39,756
...everything was gone.
262
00:23:39,840 --> 00:23:44,118
And I had not one specimen to illustrate
the unknown lands I had trod,
263
00:23:44,200 --> 00:23:47,670
or to call back the recollection
of the wild scenes I had beheld.
264
00:23:47,760 --> 00:23:50,718
But such regrets, I knew, were vain.
265
00:23:50,800 --> 00:23:55,032
And I tried to think as little as possible
about what might have been,
266
00:23:55,120 --> 00:23:59,079
and to occupy myself with the state of things
which actually existed."
267
00:24:16,520 --> 00:24:20,718
Alfred Wallace returned from the tropics,
as Darwin had done,
268
00:24:20,800 --> 00:24:25,874
convinced that related species diverge
from a common stock...
269
00:24:26,920 --> 00:24:30,833
...and nonplussed as to why they diverged.
270
00:24:30,920 --> 00:24:33,195
What Wallace did not know
271
00:24:33,280 --> 00:24:39,594
was that Darwin had hit on the explanation
two years after he returned to England.
272
00:24:40,800 --> 00:24:44,475
Darwin recounts that in 1838
273
00:24:44,560 --> 00:24:50,510
he was reading the Essay On Population,
by the Reverend Thomas Malthus...
274
00:24:52,280 --> 00:24:56,068
..."for amusement," says Darwin,
meaning it was not part of his serious reading.
275
00:24:56,160 --> 00:24:59,118
And he was struck by a thought in Malthus.
276
00:25:03,800 --> 00:25:09,079
Malthus had said
that population multiplies faster than food.
277
00:25:09,160 --> 00:25:14,917
If that's true of animals,
then they must compete to survive.
278
00:25:15,000 --> 00:25:18,470
So that nature acts as a selective force,
279
00:25:18,560 --> 00:25:23,236
killing off the weak
and forming new species from the survivors
280
00:25:23,320 --> 00:25:25,356
who are fitted to their environment.
281
00:25:26,800 --> 00:25:32,591
"Here, I had at last got a theory
by which to work," says Darwin.
282
00:25:32,680 --> 00:25:35,592
And you'd think that a man who said that
283
00:25:35,680 --> 00:25:39,593
would set to work, write papers,
go out and lecture.
284
00:25:39,680 --> 00:25:41,636
Nothing of the kind.
285
00:25:41,720 --> 00:25:47,795
For four years,
Darwin did not even commit the theory to paper.
286
00:25:47,880 --> 00:25:53,432
Only in 1842,
he wrote a draft of 35 pages in pencil.
287
00:25:54,480 --> 00:25:59,395
And two years later,
he expanded it to 230 pages in ink.
288
00:26:00,840 --> 00:26:05,118
And that draft,
he deposited with a sum of money
289
00:26:05,200 --> 00:26:08,795
and instructions to his wife
to publish it if he died.
290
00:26:11,600 --> 00:26:17,596
We feel that Darwin would really have liked
to die before he published the theory,
291
00:26:17,680 --> 00:26:22,151
provided after his death
the priority should come to him.
292
00:26:22,240 --> 00:26:24,913
That's a strange character.
293
00:26:25,000 --> 00:26:32,111
It speaks for a man who knew that he was
saying something deeply shocking to the public,
294
00:26:32,200 --> 00:26:34,350
certainly deeply shocking to his wife.
295
00:26:34,440 --> 00:26:38,399
And who was himself, to some extent,
shocked by it.
296
00:26:41,000 --> 00:26:45,755
The hypochondria.
Yes, he had some infection from the tropics.
297
00:26:45,840 --> 00:26:47,432
The bottles of medicine...
298
00:26:47,520 --> 00:26:53,436
the enclosed, somewhat suffocating atmosphere
of his house and study...
299
00:26:53,520 --> 00:26:55,078
the afternoon naps...
300
00:26:55,160 --> 00:26:57,116
the delay in writing...
301
00:26:57,200 --> 00:26:59,156
the refusal to argue in public...
302
00:26:59,240 --> 00:27:04,394
All those speak for a mind
that did not want to face the public.
303
00:27:06,840 --> 00:27:11,118
The younger Wallace, of course,
was held by none of these inhibitions.
304
00:27:11,200 --> 00:27:16,149
Brashly he went off, in spite of all adversities,
to the Far East.
305
00:27:16,240 --> 00:27:21,758
And there, on a night of fever,
he recalled the same book by Malthus,
306
00:27:21,840 --> 00:27:27,472
and had the same explanation flash on him
that had struck Darwin.
307
00:27:27,560 --> 00:27:29,516
(Thunderclap)
308
00:27:32,040 --> 00:27:33,996
(Rumble of thunder)
309
00:27:35,400 --> 00:27:38,119
WALLACE:
"It occurred to me to ask the question:
310
00:27:39,400 --> 00:27:42,995
Why do some die and some live?
311
00:27:44,320 --> 00:27:46,754
The answer was suddenly clear.
312
00:27:47,800 --> 00:27:51,918
From the effects of disease,
the most healthy escaped.
313
00:27:52,000 --> 00:27:55,754
From enemies, the strongest, the swiftest,
or the most cunning.
314
00:27:55,840 --> 00:27:59,469
From famine, the best hunters,
or those with the best digestion.
315
00:28:01,880 --> 00:28:08,194
Then I at once saw that the ever present
variability of all living things
316
00:28:08,280 --> 00:28:10,396
would furnish the material from which,
317
00:28:10,480 --> 00:28:14,951
by the mere weeding out of those less adapted
to the actual conditions,
318
00:28:15,040 --> 00:28:17,952
the fittest alone would continue the race."
319
00:28:24,680 --> 00:28:26,636
~ MENDELSSOHN: On Wings Of Song
320
00:28:43,400 --> 00:28:46,836
"The more I thought it over,
the more I became convinced
321
00:28:46,920 --> 00:28:51,471
that I had, at length,
found the long sought for law of nature
322
00:28:51,560 --> 00:28:54,677
that solved the problem of the origin of species.
323
00:28:55,760 --> 00:28:58,035
I waited anxiously for the termination of my fit
324
00:28:58,120 --> 00:29:01,396
so that I might at once make notes
for a paper on the subject.
325
00:29:01,480 --> 00:29:04,552
The same evening, I did this pretty fully.
326
00:29:04,640 --> 00:29:07,916
And on the two succeeding evenings,
wrote it out carefully
327
00:29:08,000 --> 00:29:13,154
in order to send it to Darwin by the next post,
which would leave in a day or two."
328
00:29:15,840 --> 00:29:18,354
Darwin received Wallace's paper
329
00:29:18,440 --> 00:29:23,355
here in his study at Down House,
in June of 1858.
330
00:29:24,400 --> 00:29:26,356
He was at a loss to know what to do.
331
00:29:27,600 --> 00:29:33,232
But friends arranged that Wallace's paper
and one by Darwin should be read,
332
00:29:33,320 --> 00:29:39,190
in the absence of both, at the next meeting of
the Linnean Society in London, next month.
333
00:29:40,640 --> 00:29:43,029
The papers made no stir at all.
334
00:29:44,080 --> 00:29:47,117
But Darwin 's hand had been forced.
335
00:29:47,200 --> 00:29:52,797
Wallace was, as Darwin described him,
"generous and noble."
336
00:29:52,880 --> 00:30:00,150
And so, Darwin wrote The Origin Of Species
and published it at the end of 1859.
337
00:30:01,200 --> 00:30:04,954
And it was instantly a sensation.
338
00:30:05,040 --> 00:30:06,758
And a bestseller.
339
00:30:07,800 --> 00:30:10,268
The theory of evolution by natural selection
340
00:30:10,360 --> 00:30:17,357
was certainly the most important
single scientific innovation in the 19th century.
341
00:30:18,840 --> 00:30:24,198
Every generalisation about biology
is a slice in time,
342
00:30:24,280 --> 00:30:32,039
and it's evolution which is the real creator
of originality and novelty in the universe.
343
00:30:32,120 --> 00:30:34,076
And if that is so,
344
00:30:34,160 --> 00:30:38,950
then each one of us traces back
through that evolutionary process
345
00:30:39,040 --> 00:30:40,758
right to the beginnings of life.
346
00:30:41,800 --> 00:30:44,678
Darwin, of course,
and Wallace looked at behaviour,
347
00:30:45,760 --> 00:30:49,992
they looked at bones, at fossils.
348
00:30:51,040 --> 00:30:53,793
And today, we look even more deeply...
349
00:30:54,920 --> 00:30:57,150
...at the chemistry that we all share.
350
00:30:59,360 --> 00:31:03,433
The blood in my finger at this moment
has come...
351
00:31:04,720 --> 00:31:07,314
...by some millions of steps...
352
00:31:08,360 --> 00:31:15,232
...from the very first primeval molecules
that were able to reproduce themselves
353
00:31:15,320 --> 00:31:20,110
oh, perhaps 3,000 million years ago.
354
00:31:21,240 --> 00:31:24,596
That is evolution in its contemporary conception.
355
00:31:25,760 --> 00:31:33,030
The processes by which this has happened
in part depend on... heredity...
356
00:31:34,320 --> 00:31:37,517
...which neither Darwin nor Wallace
really understood...
357
00:31:38,560 --> 00:31:46,478
...and in part on chemical structure which, again,
was the province of French scientists,
358
00:31:46,560 --> 00:31:49,358
rather than of British naturalists.
359
00:31:50,960 --> 00:31:52,916
But one thing they all had in common.
360
00:31:53,000 --> 00:31:59,917
From that moment, it was no longer possible
to believe any story which supposed
361
00:32:00,000 --> 00:32:06,235
that at any time now there could be created
once again the beginning of life.
362
00:32:13,000 --> 00:32:17,312
Most people believed that creation
had not stopped with the Bible.
363
00:32:18,520 --> 00:32:22,559
They thought that the sun breeds crocodiles
from the mud of the Nile.
364
00:32:25,440 --> 00:32:30,230
Mice were supposed to grow of themselves
in heaps of dirty, old clothes.
365
00:32:31,280 --> 00:32:35,671
And it was obvious that the origin of bluebottles
is bad meat.
366
00:32:43,720 --> 00:32:48,840
Maggots mst be created inside apples.
How else did they get there?
367
00:32:52,160 --> 00:32:56,073
All these creatures were believed to come to life
spontaneously, without the benefit of parents.
368
00:33:06,320 --> 00:33:11,713
Fables about creatures that come to life
spontaneously are very ancient
369
00:33:11,800 --> 00:33:13,756
and are still believed.
370
00:33:13,840 --> 00:33:19,039
Although Louis Pasteur
disproved them beautifully in the 1860s.
371
00:33:20,080 --> 00:33:25,916
He did much of that work here, in the house
that he loved to come back to every year,
372
00:33:26,000 --> 00:33:28,958
in Arbois, in the French Jura.
373
00:33:29,800 --> 00:33:31,552
This is the wine cellar of his house.
374
00:33:32,600 --> 00:33:35,239
Arbois is a wine-growing district.
375
00:33:39,000 --> 00:33:42,959
Pasteur had done work on fermentation
before that.
376
00:33:43,040 --> 00:33:44,996
The fermentation of milk.
377
00:33:45,080 --> 00:33:48,356
The word "pasteurisation" reminds us of that.
378
00:33:49,400 --> 00:33:51,356
But he was at the height of his power.
379
00:33:52,480 --> 00:33:57,759
In 1863, he was 40
when the Emperor of France asked him
380
00:33:57,840 --> 00:34:02,391
to look into what goes wrong
with the fermentation of wine.
381
00:34:03,600 --> 00:34:05,750
And he solved that problem in two years.
382
00:34:08,200 --> 00:34:14,116
It's ironic to remember that they were among
the best wine years that there have ever been.
383
00:34:14,200 --> 00:34:20,833
To this day, 1864 is remembered
as being like no other year.
384
00:34:27,840 --> 00:34:30,798
"The wine is a sea of organisms,"...
385
00:34:31,920 --> 00:34:33,273
...said Pasteur.
386
00:34:33,360 --> 00:34:36,830
"By some it lives, by some it decays."
387
00:34:38,800 --> 00:34:43,555
There are two things... striking in that thought.
388
00:34:44,680 --> 00:34:50,277
One is that Pasteur found organisms
that live without oxygen.
389
00:34:51,320 --> 00:34:54,278
At the time, that was just a nuisance
to wine growers.
390
00:34:54,360 --> 00:35:01,232
But since then, it's turned out to be crucial
to the understanding of the beginning of life...
391
00:35:02,280 --> 00:35:06,956
...because then, the earth was without oxygen.
392
00:35:08,320 --> 00:35:10,276
And second,
393
00:35:10,360 --> 00:35:13,875
Pasteur had a remarkable technique...
394
00:35:15,600 --> 00:35:22,073
...by which he could see the traces of life
in the liquid.
395
00:35:24,800 --> 00:35:27,553
In his twenties, he had made his reputation...
396
00:35:28,680 --> 00:35:36,234
...by showing... that there are molecules
that have a characteristic shape.
397
00:35:37,720 --> 00:35:39,278
And he had since shown
398
00:35:39,360 --> 00:35:45,549
that that is the thumbprint
of their having been through the process of life.
399
00:35:47,120 --> 00:35:52,035
That has turned out to be so profound
and so puzzling a discovery
400
00:35:52,120 --> 00:35:57,672
that it's right to look at it
in Pasteur's own laboratory upstairs.
401
00:36:02,880 --> 00:36:07,396
PASTEUR: "How does one account for
the working of the vintage in the vat...
402
00:36:08,440 --> 00:36:10,396
...of dough left to rise...
403
00:36:12,000 --> 00:36:14,036
...or the souring of curdling milk...
404
00:36:15,680 --> 00:36:19,753
...of dead leaves and plants buried in the soil
and turning to humus?
405
00:36:21,920 --> 00:36:26,948
I must, in fact, confess that my research
has long been dominated by the idea that
406
00:36:27,040 --> 00:36:28,996
the structure of substances,
407
00:36:29,080 --> 00:36:32,516
from the point of view of left-handed
and right-handedness,
408
00:36:32,600 --> 00:36:34,556
if all else is equal,
409
00:36:34,640 --> 00:36:40,112
plays an important part in the most intimate laws
of the organisation of living beings...
410
00:36:41,400 --> 00:36:45,075
...and enters into the most obscure corners
of their physiology."
411
00:36:58,640 --> 00:36:59,993
Right hand...
412
00:37:01,520 --> 00:37:02,873
...left hand.
413
00:37:04,000 --> 00:37:08,790
That was the deep clue that Pasteur followed
in his study of life.
414
00:37:09,840 --> 00:37:11,796
The world is full of things...
415
00:37:13,920 --> 00:37:18,994
...whose right-hand version is different from
a left-hand version.
416
00:37:19,080 --> 00:37:23,039
A right-handed corkscrew,
as against a left-handed.
417
00:37:23,120 --> 00:37:25,588
A right snail, as against a left one.
418
00:37:25,680 --> 00:37:29,070
Above all, the two hands.
419
00:37:30,280 --> 00:37:33,192
They can be mirrored one in the other...
420
00:37:34,440 --> 00:37:36,795
...but they cannot be turned in such a way
421
00:37:36,880 --> 00:37:41,510
that the right hand and the left hand
become interchangeable.
422
00:37:44,760 --> 00:37:49,834
That was known in Pasteur's time
to be true also of some crystals,
423
00:37:49,920 --> 00:37:56,632
whose facets are so arranged that there are
right-hand versions... and left-hand versions.
424
00:37:58,640 --> 00:38:02,030
Pasteur made wooden models of such crystals.
425
00:38:03,120 --> 00:38:06,157
In his first piece of research,
he had hit on the notion
426
00:38:06,240 --> 00:38:10,597
that there must be right-handed
and left-handed molecules too,
427
00:38:10,680 --> 00:38:15,356
and what is true of the crystal
must reflect a property of the molecule itself.
428
00:38:16,480 --> 00:38:23,033
And that must be displayed by the fact that
when you put them into solution,
429
00:38:23,120 --> 00:38:26,590
and shine polarised light through them,
430
00:38:26,680 --> 00:38:31,913
the right-hand molecules
must turn the light to the right,
431
00:38:32,000 --> 00:38:36,869
and the left-hand molecules
must direct the light to the left.
432
00:38:39,080 --> 00:38:45,519
A solution of crystals, all of one shape,
will behave unsymmetrically in a polarimeter.
433
00:38:47,040 --> 00:38:49,554
As the polarising disc is turned,
434
00:38:49,640 --> 00:38:53,315
the solution will look alternately dark...
435
00:38:54,360 --> 00:38:56,032
...and light,
436
00:38:56,120 --> 00:38:59,351
and dark... and light again.
437
00:39:00,400 --> 00:39:04,439
And a chemical solution from living cells
does just that.
438
00:39:05,480 --> 00:39:10,554
For the first time,
Pasteur had linked life with chemical structure.
439
00:39:10,640 --> 00:39:13,074
From that powerful thought,
440
00:39:13,160 --> 00:39:19,030
it follows that we must be able
to link evolution with chemistry.
441
00:39:20,880 --> 00:39:24,190
The theory of evolution
is no longer a battleground.
442
00:39:24,280 --> 00:39:29,559
That's because the evidence for it
is so much richer and more varied now
443
00:39:29,640 --> 00:39:33,997
than it was in the days of Darwin and Wallace.
444
00:39:35,040 --> 00:39:40,034
The most interesting and modern evidence
comes from our body chemistry.
445
00:39:41,200 --> 00:39:43,156
Let me take a practical example.
446
00:39:43,240 --> 00:39:49,190
I'm moving my hand at this moment
because the muscles contain a store of oxygen.
447
00:39:49,280 --> 00:39:54,593
And that's been put there
by a protein called myoglobin.
448
00:39:55,720 --> 00:40:00,840
That protein has just over 150 amino acids
to make it up.
449
00:40:02,040 --> 00:40:07,319
The number is the same in me
and all the other animals that use myoglobin.
450
00:40:08,560 --> 00:40:13,873
But the amino acids themselves
are slightly different.
451
00:40:14,920 --> 00:40:21,393
Between me and the chimpanzee,
there is just one difference in an amino acid.
452
00:40:22,440 --> 00:40:26,353
Between me and the bushbaby,
which is a lower primate,
453
00:40:26,440 --> 00:40:29,477
there are several amino acid differences.
454
00:40:29,560 --> 00:40:34,270
And then, between me and the sheep,
the mouse,
455
00:40:34,360 --> 00:40:37,750
the number of differences increases.
456
00:40:38,920 --> 00:40:41,832
It's the number of amino acid differences
457
00:40:41,920 --> 00:40:48,678
which is a measure of the evolutionary distance
between me and the other mammals.
458
00:40:51,200 --> 00:40:57,469
It's clear that we have to look for
the evolutionary progress of life
459
00:40:57,560 --> 00:41:01,439
in a build-up of chemical molecules.
460
00:41:01,520 --> 00:41:03,556
~ PROKOFIEV: Love For Three Oranges
461
00:41:06,720 --> 00:41:14,593
And that build-up must begin from the materials
that boiled on the earth at its birth.
462
00:41:47,280 --> 00:41:52,877
To talk sensibly about the beginning of life,
we have to be very realistic.
463
00:41:52,960 --> 00:41:56,270
We have to ask a historical question.
464
00:41:57,320 --> 00:42:00,118
4,000 million years ago,
465
00:42:00,200 --> 00:42:04,318
before life began,
when the earth was very young,
466
00:42:04,400 --> 00:42:09,076
what was the surface of the earth,
what was its atmosphere like?
467
00:42:09,960 --> 00:42:13,794
Well, it was like a volcanic neighbourhood
anywhere,
468
00:42:13,880 --> 00:42:17,998
a cauldron of steam and ammonia and gases.
469
00:42:18,080 --> 00:42:19,593
What gases?
470
00:42:19,680 --> 00:42:21,636
One gas was absent.
471
00:42:21,720 --> 00:42:24,314
There was no free oxygen.
472
00:42:24,400 --> 00:42:28,951
That's crucial,
because oxygen is produced by the plants
473
00:42:29,040 --> 00:42:33,318
and did not exist
before life existed in a free state.
474
00:42:35,240 --> 00:42:41,679
These gases in their reducing atmosphere,
dissolved weakly in the oceans,
475
00:42:41,760 --> 00:42:47,835
how would they react now, under the action
of lightning, electric discharges,
476
00:42:47,920 --> 00:42:50,070
under the action of ultraviolet light,
477
00:42:50,160 --> 00:42:53,391
which is very important in every theory of life,
478
00:42:53,480 --> 00:42:56,597
and which could penetrate
in the absence of oxygen.
479
00:42:57,680 --> 00:43:03,471
That question was answered by a beautiful
experiment by Stanley Miller in America,
480
00:43:03,560 --> 00:43:05,516
round about 1950.
481
00:43:08,400 --> 00:43:10,960
He put the atmosphere in a flask.
482
00:43:11,040 --> 00:43:12,473
The methane,
483
00:43:12,560 --> 00:43:14,516
the hydrogen cyanide,
484
00:43:14,600 --> 00:43:16,556
the ammonia, the water,
485
00:43:16,640 --> 00:43:18,596
the oxides of carbon...
486
00:43:18,680 --> 00:43:22,275
and went on for day after day after day,
487
00:43:22,360 --> 00:43:24,874
boiled and bubbled them up,
488
00:43:24,960 --> 00:43:32,469
put an electric discharge through them,
to simulate lightning and other violent forces.
489
00:43:32,560 --> 00:43:34,516
~ PROKOFIEV: Love For Three Oranges
490
00:43:49,040 --> 00:43:52,032
And visibly, the mixture darkened.
491
00:43:52,120 --> 00:43:53,439
Why?
492
00:43:53,520 --> 00:43:58,469
Because, on testing, it was found
that amino acids had been formed in it.
493
00:43:59,520 --> 00:44:01,795
That's a crucial step forward,
494
00:44:01,880 --> 00:44:06,078
because amino acids
are the building blocks of life.
495
00:44:06,160 --> 00:44:08,913
From them, the proteins are made.
496
00:44:09,000 --> 00:44:14,199
And proteins are the constituents
of all living things.
497
00:44:16,040 --> 00:44:18,508
~ PROKOFIEV: Love For Three Oranges
498
00:44:24,760 --> 00:44:31,472
We used to think that life had to begin
in those sultry, electric conditions.
499
00:44:31,560 --> 00:44:33,516
Until a few years ago.
500
00:44:34,560 --> 00:44:38,678
And then, it began to occur to a few scientists
501
00:44:38,760 --> 00:44:44,357
that there is another set of extreme conditions
which may be as powerful.
502
00:44:45,800 --> 00:44:48,678
That is the presence of ice.
503
00:44:50,040 --> 00:44:51,996
It's a strange thought.
504
00:44:52,080 --> 00:44:57,359
But ice has two properties
which make it very attractive
505
00:44:57,440 --> 00:45:00,989
in the formation of simple, basic molecules.
506
00:45:02,040 --> 00:45:06,909
First of all, the process of freezing
concentrates the material
507
00:45:07,000 --> 00:45:12,518
which, at the beginning of time,
must have been very dilute in the oceans.
508
00:45:13,640 --> 00:45:20,398
And secondly, the crystalline structure of ice
makes it possible for molecules to line up
509
00:45:20,480 --> 00:45:24,917
in a way which is certainly important
at every stage of life.
510
00:45:26,400 --> 00:45:31,713
At any rate, Leslie Orgel
did a number of elegant experiments
511
00:45:31,800 --> 00:45:34,519
of which I will describe the simplest.
512
00:45:35,880 --> 00:45:38,314
He took some of the basic constituents
513
00:45:38,400 --> 00:45:43,235
which were sure to be present in
the atmosphere of the earth at an early time.
514
00:45:43,320 --> 00:45:45,276
Hydrogen cyanide is one.
515
00:45:45,360 --> 00:45:47,112
Ammonia is another.
516
00:45:48,160 --> 00:45:50,993
He made a dilute solution of them in water
517
00:45:51,080 --> 00:45:56,074
and then froze the solution
over a period of several days.
518
00:45:56,160 --> 00:45:59,994
The time-lapse photographs
show what happens.
519
00:46:00,080 --> 00:46:07,031
The concentrated material is pushed
into a sort of tiny iceberg to the top,
520
00:46:07,120 --> 00:46:10,874
and there,
the presence of a small amount of colour
521
00:46:10,960 --> 00:46:15,556
reveals that organic molecules
have been formed.
522
00:46:15,640 --> 00:46:18,473
Some amino acids, no doubt.
523
00:46:18,560 --> 00:46:20,516
But most important,
524
00:46:20,600 --> 00:46:26,709
Orgel found that he had formed
one of the four fundamental constituents
525
00:46:26,800 --> 00:46:31,157
in the genetic alphabet which directs all life.
526
00:46:31,240 --> 00:46:37,315
He had made adenine,
one of the four bases in DNA.
527
00:46:39,520 --> 00:46:45,072
It may indeed be
that the alphabet of life in DNA
528
00:46:45,160 --> 00:46:50,109
was formed in these sorts of conditions
and not in tropical conditions.
529
00:46:52,800 --> 00:46:57,794
Were the chemicals here on earth at that time
unique to us?
530
00:46:57,880 --> 00:46:59,518
We used to think so.
531
00:46:59,600 --> 00:47:03,036
But the most recent evidence is different.
532
00:47:04,080 --> 00:47:09,871
Within the last years,
there have been found the spectral traces
533
00:47:09,960 --> 00:47:13,396
in the interstellar spaces of molecules
534
00:47:13,480 --> 00:47:17,678
which we never thought could be formed
out in those frigid regions.
535
00:47:19,400 --> 00:47:21,356
Hydrogen cyanide...
536
00:47:23,000 --> 00:47:24,956
...cyanoacetylene...
537
00:47:27,720 --> 00:47:29,676
...formaldehyde.
538
00:47:29,760 --> 00:47:34,436
Those are molecules which we had
not supposed to exist elsewhere than on earth.
539
00:47:35,480 --> 00:47:40,110
It may turn out
that life had more varied beginnings
540
00:47:40,200 --> 00:47:42,760
and has more varied forms.
541
00:47:42,840 --> 00:47:48,039
It doesn 't at all follow
that the evolutionary path which life,
542
00:47:48,120 --> 00:47:52,113
if we discover it elsewhere, took resembles ours.
543
00:47:52,200 --> 00:47:56,239
It doesn 't even follow
that we shall recognise it as life.
544
00:47:58,080 --> 00:48:00,036
Or that it will recognise us.