How Did We Get Here?

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0:00:03 > 0:00:08There are some great questions that have intrigued and haunted us

0:00:08 > 0:00:11since the dawn of humanity...

0:00:30 > 0:00:33The story of our search to answer those questions

0:00:33 > 0:00:36is the story of science.

0:00:38 > 0:00:41Of all human endeavours, science has had the greatest

0:00:41 > 0:00:42impact on our lives,

0:00:42 > 0:00:46on how we see the world and how we see ourselves.

0:00:46 > 0:00:53Its ideas, its achievements, its results are all around us.

0:00:53 > 0:00:58So, how did we arrive at the modern world?

0:00:58 > 0:01:02Well, that is more surprising and more human than you might think.

0:01:07 > 0:01:11The history of science is often told as a series of eureka moments -

0:01:11 > 0:01:14the ultimate triumph of the rational mind.

0:01:14 > 0:01:17The truth is that power and passion,

0:01:17 > 0:01:23rivalry and sheer blind chance have played equally significant parts.

0:01:25 > 0:01:29In this series, I'll be offering a different view

0:01:29 > 0:01:33of how science happens. It has been shaped as much by

0:01:33 > 0:01:36what's outside the laboratory as inside.

0:01:36 > 0:01:37Whoa!

0:01:39 > 0:01:43This is the story of how history made science and science

0:01:43 > 0:01:47made history, and how the ideas that were generated changed our world.

0:01:49 > 0:01:51It is a tale of...

0:02:06 > 0:02:09This time, the most personal question we've asked...

0:02:26 > 0:02:28How did we get here?

0:02:28 > 0:02:33It's a question that provokes fierce argument and huge controversy.

0:02:33 > 0:02:36And that's because it gets to the heart of our human origins,

0:02:36 > 0:02:41our very significance. And yet, until relatively recently,

0:02:41 > 0:02:45it was not a question that people felt they had to keep asking.

0:02:45 > 0:02:49Most people believed they already knew the answer,

0:02:49 > 0:02:53handed down in religious text or in creation stories.

0:02:53 > 0:02:55We and everything else on earth

0:02:55 > 0:02:59had been put here by some kind of supernatural power.

0:03:12 > 0:03:15What's special about this question

0:03:15 > 0:03:19is not how long it took to get answered, but how long it took

0:03:19 > 0:03:21to get asked as a scientific question.

0:03:21 > 0:03:25And it's a story that begins over here.

0:03:38 > 0:03:40'The great voyages of discovery,

0:03:40 > 0:03:44of the 15th Century, heralded the start of the modern age.

0:03:48 > 0:03:51Advances in navigation and shipbuilding allowed

0:03:51 > 0:03:57European adventurers to explore and exploit the rest of the globe.

0:04:02 > 0:04:07We're absolutely storming along now, powered by the trade winds.

0:04:07 > 0:04:10And over there is the Caribbean island of Jamaica.

0:04:11 > 0:04:15In 1494, Christopher Columbus landed here.

0:04:15 > 0:04:18It was a completely unknown part of the world,

0:04:18 > 0:04:22at least unknown to Europeans. It is the Americas.

0:04:29 > 0:04:36The discovery of the Americas sent shock waves through European civilization.

0:04:36 > 0:04:41New peoples, new plants, new animals.

0:04:42 > 0:04:46The early explorers arrived utterly convinced that they were special,

0:04:46 > 0:04:51set apart from the rest of nature. The pinnacle of God's creation.

0:04:57 > 0:05:01Yet what they found here would begin to challenge that.

0:05:03 > 0:05:08And for me, the story begins with a man called Hans Sloane.

0:05:08 > 0:05:12An Irish doctor who arrived in Jamaica in 1687 to take up

0:05:12 > 0:05:17the lucrative post of personal physician to the island's Governor.

0:05:22 > 0:05:25To be fair to Sloane, he was more than simply an adventurer

0:05:25 > 0:05:29in search of a fast buck. He was also a passionate botanist

0:05:29 > 0:05:32who loved to go exploring the island on horseback with a guide.

0:05:32 > 0:05:34- OK, Marlin, are you ready to go? - Yep.- Lovely.

0:05:36 > 0:05:38HORSE BLUSTERS

0:05:40 > 0:05:42Elegantly done.

0:05:45 > 0:05:47Don't want to be left behind.

0:05:59 > 0:06:01My guide, Marlin Beale, is a botanist.

0:06:01 > 0:06:06And together we're heading for the Blue Mountains

0:06:06 > 0:06:09where Sloane would come face to face with what he described as,

0:06:09 > 0:06:12"all that is extraordinary in nature."

0:06:14 > 0:06:19I know that Sloane was a doctor and he was particularly interested in plants,

0:06:19 > 0:06:21- which had any sort of medicinal quality.- Yes.

0:06:21 > 0:06:24- So if you see any, do let me know. - Definitely, I will.

0:06:24 > 0:06:28'Since most 17th Century medicines came from plants,

0:06:28 > 0:06:31'it's not surprising that finding new species

0:06:31 > 0:06:33'was high on Sloane's agenda.'

0:06:35 > 0:06:38A-ha, here we go.

0:06:38 > 0:06:40- Smell it.- Very pretty.

0:06:40 > 0:06:42Yeah. Taste it, if you want.

0:06:42 > 0:06:44Which end do I taste?

0:06:44 > 0:06:46That end, the cut end.

0:06:47 > 0:06:50That's ginger, isn't it?

0:06:50 > 0:06:51It's wild ginger.

0:06:53 > 0:06:56Interesting, because Sloane wrote quite a lot about wild ginger.

0:06:56 > 0:06:59He believed that ginger was very good for the stomach.

0:06:59 > 0:07:03I don't know about that. It's certainly good for sea sickness.

0:07:03 > 0:07:06If you were doing a two month voyage across the Atlantic, this would be useful.

0:07:06 > 0:07:11Sloane also claimed that wild ginger was good for treating cancers.

0:07:11 > 0:07:14I'm not sure about that either. Quite tasty though.

0:07:20 > 0:07:27Now, an interest in nature wasn't confined to collectors like Sloane.

0:07:27 > 0:07:30Because in nature, and particularly plants,

0:07:30 > 0:07:33lay the foundations of European imperial power.

0:07:35 > 0:07:40Trading vessels criss-crossed the globe, bringing home all sorts of natural produce,

0:07:40 > 0:07:44from tobacco and spices to tea and timber,

0:07:44 > 0:07:47the botanical booty was practically limitless.

0:07:49 > 0:07:51Even the ships, which carried the goods,

0:07:51 > 0:07:53were themselves made out of plants.

0:07:53 > 0:07:59There were trees for the framework, hemp provided the sails and ropes,

0:07:59 > 0:08:03and they used pine resin to produce pitch,

0:08:03 > 0:08:07which was used to waterproof the ships.

0:08:12 > 0:08:17What distinguished Sloane from most traders and plantation owners

0:08:17 > 0:08:23was an interest in all of nature. Not just plants but also animals.

0:08:24 > 0:08:29This interest would open the world's eyes to the beauty of God's creation

0:08:29 > 0:08:35and crucially to the puzzle of its incredible diversity.

0:08:37 > 0:08:39There aren't very many big animals here on Jamaica,

0:08:39 > 0:08:42but there are an awful lot of lizards and what Marlin

0:08:42 > 0:08:45is about to do is make a little noose I think, is that right?

0:08:45 > 0:08:47- Yes.- And hopefully we'll capture a few lizards.

0:08:47 > 0:08:50Is this the sort of thing that Sloane might have used?

0:08:50 > 0:08:54Possibly, because this would be the most conventional method at that time.

0:08:54 > 0:08:56Just tight.

0:08:56 > 0:08:59What we've got to do now is persuade the lizard to stick its...

0:08:59 > 0:09:02- It's head inside. So we've got our noose.- Very neat.

0:09:02 > 0:09:07A beautiful noose for catching lizards in the style of Hans Sloane.

0:09:10 > 0:09:12Where are we likely to find them, Marlin?

0:09:12 > 0:09:15Well, we can find some on the ground or even on trees.

0:09:15 > 0:09:19So, both looking on the ground and on trees is great.

0:09:19 > 0:09:22'It was this type of hands on approach...'

0:09:22 > 0:09:24I think there's one over here.

0:09:24 > 0:09:28'..that enabled Sloane to collect so many different specimens

0:09:28 > 0:09:31- 'of Jamaican wildlife.' - MICHAEL YELPS

0:09:31 > 0:09:34He jumped. I think he's gone.

0:09:37 > 0:09:40- Michael.- Have you seen something?

0:09:40 > 0:09:46Yes. This one right, right there, do you see? Let's have a go.

0:09:50 > 0:09:53- Brilliant. Is he safe to hold?- Yeah.

0:09:53 > 0:09:58Maybe a bit feisty. So I'm going to get the noose off of him.

0:09:58 > 0:10:01How many different species of lizards are there?

0:10:01 > 0:10:06There are many different species, over 20 different species.

0:10:08 > 0:10:10- I think we've done very well.- Yeah.

0:10:24 > 0:10:28This book has illustrations of just some of the things that Sloane

0:10:28 > 0:10:31captured in Jamaica. A snake there.

0:10:31 > 0:10:33There's our friends, the lizards.

0:10:33 > 0:10:36I think the one I helped capture, is the one in the middle there.

0:10:36 > 0:10:40The book is just full of beautiful drawings.

0:10:40 > 0:10:43Birds, fishes...

0:10:43 > 0:10:47The thing is that Hans Sloane came to Jamaica not just to revel in its beauty,

0:10:47 > 0:10:54but to record everything he saw, which he did in enormous detail, so that other people who

0:10:54 > 0:10:59couldn't come here could enjoy and learn from what he had discovered.

0:11:05 > 0:11:10After 15 months on the island, Sloane returned to England.

0:11:10 > 0:11:16He brought back with him some 800 samples of flora and fauna,

0:11:16 > 0:11:21a fully grown crocodile and a recipe for drinking chocolate.

0:11:21 > 0:11:25Unlike many explorers who returned from the Americas with tall tales

0:11:25 > 0:11:30of giant sea serpents and men whose heads grow beneath their shoulders,

0:11:30 > 0:11:34Sloane returned with real data and real specimens.

0:11:39 > 0:11:46There was no reason as yet to think that all this diversity had anything to do with us.

0:11:46 > 0:11:52But it did unsettle traditional ideas of God's creation of the natural world.

0:11:52 > 0:11:55For people who believed that God had created the world

0:11:55 > 0:11:58and everything in it, permanent and perfect,

0:11:58 > 0:12:01this was also utterly bewildering.

0:12:01 > 0:12:07Why had God bothered to make so many small and apparently pointless variations on a theme?

0:12:07 > 0:12:11Why so many lizards? Why so many beetles?

0:12:11 > 0:12:15The questions started to come thick and fast.

0:12:21 > 0:12:26By the time Hans Sloane died in 1753, he had put together

0:12:26 > 0:12:30the world's greatest collection of natural objects.

0:12:30 > 0:12:34Most of which are still with us today.

0:12:34 > 0:12:37In front of me we have part of the Sloane Herbarium.

0:12:39 > 0:12:42There are many, many thousands of objects

0:12:42 > 0:12:45about 14,000 of these vegetable substances.

0:12:45 > 0:12:49Flowers, fruits, dried objects, which we can't press.

0:12:51 > 0:12:55'And with that there are about 270 bound volumes

0:12:55 > 0:12:57'with many, many thousands of specimens in.'

0:13:00 > 0:13:03So vast was Sloane's hoard of wonders

0:13:03 > 0:13:06that it was moved to a new type of institution

0:13:06 > 0:13:10beginning to appear across Europe.

0:13:12 > 0:13:14The national museum.

0:13:17 > 0:13:20Private collections, like Sloane's,

0:13:20 > 0:13:23could now be seen by a much wider audience.

0:13:28 > 0:13:33Bringing nature out of the wilderness and into the every day world.

0:13:43 > 0:13:46This new curiosity about life on earth

0:13:46 > 0:13:51would bring us closer to the question - how did we get here?

0:13:51 > 0:13:56It was fuelled by voyages of discovery and the money to be made from nature,

0:13:56 > 0:13:59by obsessive collectors, like Hans Sloane,

0:13:59 > 0:14:02who began to document nature's diversity.

0:14:06 > 0:14:12And by museums, where ordinary people could see it for themselves.

0:14:12 > 0:14:19And it now turned out that all this life also had a history, a rather rich one.

0:14:32 > 0:14:34Paris. Just after the French Revolution.

0:14:36 > 0:14:40Where the belief that God's creation was fixed and unchanging

0:14:40 > 0:14:44was about to be further undermined by a brilliant anatomist

0:14:44 > 0:14:46and a taste for new buildings.

0:14:49 > 0:14:53Paris is a city in love with its own beauty.

0:14:53 > 0:14:56Whatever events may have been dominating the headlines -

0:14:56 > 0:14:59the fall of the Bastille, the execution of the King,

0:14:59 > 0:15:01one thing has remained constant -

0:15:01 > 0:15:06the City's determination to build on its rich architectural heritage.

0:15:12 > 0:15:17Buildings began to appear, which were every bit as magnificent as their predecessors.

0:15:20 > 0:15:22'While others were added to.'

0:15:26 > 0:15:28'For example, the Louvre.

0:15:28 > 0:15:31'In the years following the Revolution, it grew

0:15:31 > 0:15:35'from a Bourbon palace into a museum large enough to house

0:15:35 > 0:15:38'France's rapidly expanding art collection.'

0:15:38 > 0:15:43But I'm less interested in what's in there than what's out here.

0:15:43 > 0:15:46And in particular this stuff - limestone.

0:15:47 > 0:15:52A rock which for centuries had been the mainstay of Parisian architecture.

0:15:54 > 0:16:00Now this limestone was hewn from a quarry that is very near to where I'm standing now.

0:16:00 > 0:16:03A hidden one, one that is down there.

0:16:13 > 0:16:17Deep beneath Paris lies an old network of stone quarries

0:16:17 > 0:16:21linked by hundreds of kilometres of connecting tunnels.

0:16:23 > 0:16:28Together they form a mirror image of the city above, right down to the street names.

0:16:34 > 0:16:38People began quarrying away underneath Paris in the middle ages.

0:16:38 > 0:16:41And they went on digging for hundreds of years.

0:16:41 > 0:16:43There should be a sign just over here.

0:16:43 > 0:16:45Yes, "3R."

0:16:45 > 0:16:47This is the old revolutionary calendar

0:16:47 > 0:16:51and it means three years after the start of the French Revolution.

0:16:51 > 0:16:54At that time, houses being built over my head

0:16:54 > 0:16:58would have contained limestone from quarries just like this one.

0:17:02 > 0:17:03Hello.

0:17:03 > 0:17:07- I'm Gilles. It's a pleasure to meet you.- And you.

0:17:07 > 0:17:11I guess actually quarrying down here must have been pretty dangerous.

0:17:12 > 0:17:13It could be dangerous.

0:17:13 > 0:17:17It's the reason why quarrymen put this hand made pillar

0:17:17 > 0:17:21to protect them from falling roof, from collapse.

0:17:21 > 0:17:23Who actually dug these areas?

0:17:23 > 0:17:26It is specific to France when you are owner of the surface,

0:17:26 > 0:17:30you are owner of the underground until the centre of the earth.

0:17:30 > 0:17:32To the centre of the earth under French law?

0:17:32 > 0:17:34- Yeah, according to the French law. - How interesting.

0:17:42 > 0:17:45'As more and more quarries were excavated,

0:17:45 > 0:17:48'people began to take a greater interest in the mysterious objects

0:17:48 > 0:17:52'they were finding embedded in the rock.'

0:17:53 > 0:17:58Ah, it's magical, isn't it? You can see there, a really clear shell.

0:17:58 > 0:18:01It must have been very strange for the workmen who first came

0:18:01 > 0:18:06down here when they realized they were looking at something which should be on the ocean floor.

0:18:08 > 0:18:12What they were looking at, of course, were fossils.

0:18:18 > 0:18:22For a long time, people had no idea what fossils really were.

0:18:22 > 0:18:25Some people claimed they'd come from the moon.

0:18:25 > 0:18:30Others that they were mud's unsuccessful attempt to turn into life.

0:18:30 > 0:18:33In fact, it wasn't until the end of the 18th Century

0:18:33 > 0:18:37that people fully appreciated they had once been living things.

0:18:37 > 0:18:42And this realization opened up a whole new window into the past.

0:18:46 > 0:18:52A past that was both ancient and unimaginably different.

0:18:57 > 0:19:00Here in France, many of those fossils

0:19:00 > 0:19:03ended up in the hands of a brilliant scientist.

0:19:03 > 0:19:06A man obsessed by old bones.

0:19:13 > 0:19:16His name was Georges Cuvier

0:19:16 > 0:19:21and he was widely regarded as the world's leading animal anatomist.

0:19:21 > 0:19:25There was barely an animal in existence

0:19:25 > 0:19:27whose remains hadn't come his way.

0:19:32 > 0:19:37There's a story about Cuvier, which I like, which I think really sums up the man.

0:19:37 > 0:19:41It's late at night and Cuvier has gone to bed...

0:19:41 > 0:19:45when one of his students dressed in a devil's costume bursts

0:19:45 > 0:19:50into his room and cries "Cuvier, Cuvier, I've come to eat you!"

0:19:52 > 0:19:57Cuvier opened one eye, calmly looked the student up and down and said,

0:19:57 > 0:20:01"All animals that have hooves and horns are herbivores -

0:20:01 > 0:20:03"you cannot eat me."

0:20:05 > 0:20:09Now the point is that Cuvier had realized

0:20:09 > 0:20:10that from a couple of features,

0:20:10 > 0:20:14you could work out the essential nature of any animal.

0:20:16 > 0:20:20This insight would lead Cuvier to propose a new, and to many minds,

0:20:20 > 0:20:24unthinkable story of life on earth.

0:20:25 > 0:20:29Now I'm no Cuvier, but I did train as a medical doctor

0:20:29 > 0:20:32and so I've seen a lot of bones, albeit human ones.

0:20:32 > 0:20:37In here I've got some fossil bones. I'm going to try and see if I can work out where they came from.

0:20:37 > 0:20:41Right. I think this is the end bit of the finger.

0:20:41 > 0:20:45But in this case is has a big claw attached.

0:20:45 > 0:20:49So I'm guessing this comes from a carnivore. I'm going to go and hunt carnivores.

0:20:52 > 0:20:56'By examining the form of any body part, Cuvier claimed

0:20:56 > 0:21:01'you could discover everything there was to know about its function.'

0:21:01 > 0:21:07It's a bit like a crocodile claw, but not really close enough.

0:21:07 > 0:21:10'And from its function, its likely source.'

0:21:10 > 0:21:14Bigger, but not bad. That's a dog.

0:21:16 > 0:21:17I think that's about right.

0:21:17 > 0:21:22I guess that this is from a hyena.

0:21:22 > 0:21:25Let's see if I'm right.

0:21:25 > 0:21:29No, close though, it's from a wolf apparently. Wolf.

0:21:31 > 0:21:35Cuvier was clearly better at this than me and this allowed him to

0:21:35 > 0:21:40identify many previously unknown fossils coming out of the ground.

0:21:43 > 0:21:49But also some remains that would have unsettling implications.

0:21:49 > 0:21:53One of the fossils that Cuvier was sent, was this one.

0:21:53 > 0:21:56It is, believe it or not, a giant tooth.

0:21:56 > 0:21:58You can tell that, because this is the enamel

0:21:58 > 0:22:00or biting layer over here.

0:22:00 > 0:22:02Now, the people who found this fossil

0:22:02 > 0:22:04were convinced it came from an elephant.

0:22:04 > 0:22:06But Cuvier had other ideas.

0:22:09 > 0:22:11The fossil I've got here is obviously much bigger

0:22:11 > 0:22:13than the elephant tooth you've got there,

0:22:13 > 0:22:16what other features did Cuvier notice were different?

0:22:16 > 0:22:19Well, you see the size of course, you are right.

0:22:19 > 0:22:22But, in this African elephant tooth

0:22:22 > 0:22:28you can see that the enamel is very different on the grinding surface.

0:22:28 > 0:22:32There are diamond enamel lamina.

0:22:32 > 0:22:34Here, there are parallel lamina

0:22:34 > 0:22:38and they are more numerous than in the African elephant.

0:22:38 > 0:22:41So there is a very important difference.

0:22:41 > 0:22:44We know that this tooth was coming from Russia

0:22:44 > 0:22:48and this tooth was called by Russians, the mammoth.

0:22:48 > 0:22:51- Ah, it's a mammoth.- A mammoth.

0:22:51 > 0:22:54So he was able to look at this and go, "It's an elephant,

0:22:54 > 0:22:56"but a much bigger elephant,

0:22:56 > 0:23:00"and a very different, sort of a third species of elephant."

0:23:03 > 0:23:09The revelation that the mammoth was a species totally distinct

0:23:09 > 0:23:15from any living elephant was nothing compared to Cuvier's next bombshell.

0:23:17 > 0:23:19Cuvier thought long and hard about mammoths

0:23:19 > 0:23:24and he came to a surprising and radical conclusion.

0:23:24 > 0:23:29Now clearly, mammoths are enormous beasts yet no-one had ever seen one,

0:23:29 > 0:23:32which suggested that at some point in the past

0:23:32 > 0:23:36mammoths, all of them, must have gone extinct.

0:23:43 > 0:23:47And it wasn't just mammoths.

0:23:47 > 0:23:51Before long, hundreds of other strange looking fossils

0:23:51 > 0:23:55began to be identified as creatures that had mysteriously disappeared

0:23:55 > 0:23:57off the face of the earth.

0:24:02 > 0:24:06The claim that some animals that had once lived had gone extinct

0:24:06 > 0:24:08raised uncomfortable questions.

0:24:08 > 0:24:13If every creature in God's fixed universe had a place and a purpose,

0:24:13 > 0:24:15why had some died off?

0:24:19 > 0:24:22The suggestion that most of the creatures

0:24:22 > 0:24:29who had ever lived were now extinct was both baffling and disturbing.

0:24:31 > 0:24:36The only consolation was that this was still a history of life,

0:24:36 > 0:24:39which we humans were separate from.

0:24:43 > 0:24:50For now, the most pressing question raised by extinction was one of time.

0:24:50 > 0:24:55And whether this fossil record of long lost species was evidence

0:24:55 > 0:25:00that the earth was older, much older than previously believed.

0:25:12 > 0:25:16The 18th Century was the age of the experiment.

0:25:16 > 0:25:21There were experiments on light, liquids,

0:25:21 > 0:25:23gases,

0:25:23 > 0:25:29but also an experiment to establish the precise age of the earth.

0:25:31 > 0:25:34The man behind the experiment was Le Comte de Buffon.

0:25:34 > 0:25:38A fabulously wealthy French aristocrat, Buffon

0:25:38 > 0:25:41was the first person to seriously attempt to measure the age of the earth,

0:25:41 > 0:25:48and he did so using some metal balls, a pocket watch and a blacksmith's forge.

0:25:54 > 0:25:57- Good morning, Brian.- Good morning. - Hi there, I'm Michael Mosley.

0:25:57 > 0:25:59- Hello, Michael. - I have a present for you.

0:25:59 > 0:26:02Two metal balls. I think you know what to do with them.

0:26:06 > 0:26:10You might imagine that back in Buffon's day, most people believed

0:26:10 > 0:26:15that the world was created in six days and was 6,000 years old.

0:26:15 > 0:26:19In fact, a lot of people, including many clerics,

0:26:19 > 0:26:22did not take the Bible that literally.

0:26:22 > 0:26:27Buffon was not unusual in suspecting that the earth might be very old.

0:26:27 > 0:26:34Where he was unusual was he was prepared to do an experiment to find out just how old.

0:26:34 > 0:26:36Right, anything I can do?

0:26:36 > 0:26:40Give it a nice long stroke, just slow, straight down.

0:26:40 > 0:26:43How long will it actually take to heat up to red hot?

0:26:43 > 0:26:46Probably the best part of an hour looking at the size of the ball.

0:26:49 > 0:26:54The experiment was actually based on a suggestion by Sir Isaac Newton.

0:26:54 > 0:26:59He said imagine the world had started off as a red, hot piece of iron.

0:26:59 > 0:27:02If you could work out how long it had taken to cool

0:27:02 > 0:27:04from that state to the present state,

0:27:04 > 0:27:08then you could work out just how old the earth really is.

0:27:11 > 0:27:16By timing how long it took for different size balls to cool down,

0:27:16 > 0:27:19Buffon was confident he could extrapolate his figures

0:27:19 > 0:27:25and establish how long it had taken the earth to reach a similar state.

0:27:25 > 0:27:27Do you reckon they're ready yet, Brian?

0:27:27 > 0:27:29Well, they're well up to temperature, yes.

0:27:29 > 0:27:31It's hot, isn't it?

0:27:31 > 0:27:35I'm trying to avoid dropping this on my toes.

0:27:35 > 0:27:37Take that down there.

0:27:39 > 0:27:42Brilliant. I've got my pocket watch here now.

0:27:42 > 0:27:45So, how long do you think before we can actually touch them?

0:27:45 > 0:27:49Looking at least 25 minutes or even longer for the small one.

0:27:49 > 0:27:53The larger ones much more mass, probably an hour.

0:28:01 > 0:28:06'A little later and I'm finally ready to start to plot my graph,

0:28:06 > 0:28:10'extrapolating my timings for the two balls,

0:28:10 > 0:28:14'to allow for the much bigger diameter of the earth.'

0:28:14 > 0:28:19Right. Now for the age of the earth using Buffon's method.

0:28:19 > 0:28:25I calculate the age of the earth at 92,000 years.

0:28:25 > 0:28:29And Buffon, well, he said it was a suspiciously accurate

0:28:29 > 0:28:3574,832 years old.

0:28:35 > 0:28:41As we now know, both these figures are in fact way out.

0:28:43 > 0:28:47Wildly inaccurate though Buffon's method was,

0:28:47 > 0:28:51it would be churlish to let that detract from his legacy.

0:28:54 > 0:28:57The important point is, that by doing the experiments

0:28:57 > 0:29:01and by publishing the results, Buffon sparked a debate.

0:29:01 > 0:29:05Not just about how old the earth actually is,

0:29:05 > 0:29:09but how and why every creature on earth came into being.

0:29:10 > 0:29:14A debate that would now be intensified

0:29:14 > 0:29:17by a new way of looking at the world.

0:29:25 > 0:29:28Standing between northern and southern Europe

0:29:28 > 0:29:32is one of the world's most formidable natural barriers -

0:29:32 > 0:29:34the Alps.

0:29:34 > 0:29:36Even as late as the mid 18th Century,

0:29:36 > 0:29:40no-one had yet climbed this region's highest peak -

0:29:40 > 0:29:42Mont Blanc.

0:29:53 > 0:30:00In 1760, a young Swiss aristocrat called Horace Benedict de Saussure

0:30:00 > 0:30:05came to the small Alpine village of Chamonix, in the foothills of Mont Blanc.

0:30:05 > 0:30:11Now, he came originally to collect plants. But he soon became so enchanted by the mountain

0:30:11 > 0:30:14that he offered a reward to the first person who could climb it.

0:30:20 > 0:30:22Despite many attempts,

0:30:22 > 0:30:26it was 26 years before anyone managed to reach the summit.

0:30:29 > 0:30:33de Saussure himself got to the top a year later.

0:30:35 > 0:30:41But de Saussure was much more than a rich man with a passion for extreme sports.

0:30:41 > 0:30:45For once he'd climbed Mont Blanc, he proceeded to carry out a series

0:30:45 > 0:30:50of experiments to discover much more about the mountain.

0:30:50 > 0:30:55Going to remote places and getting your hands dirty was a new way

0:30:55 > 0:30:59of trying to understand the processes which shaped the earth.

0:30:59 > 0:31:01And de Saussure gave it a name...

0:31:01 > 0:31:02geology.

0:31:04 > 0:31:07With its emphasis on direct observation

0:31:07 > 0:31:11this new way of looking at the earth would play a vital role

0:31:11 > 0:31:13in unravelling not just the mysteries of the planet,

0:31:13 > 0:31:20but also the entire history of life on earth including ours.

0:31:26 > 0:31:30All across Europe practically dressed men

0:31:30 > 0:31:34armed with small hammers headed off into the countryside

0:31:34 > 0:31:37in search of the earth's hidden secrets.

0:31:39 > 0:31:41Driven by an intense curiosity

0:31:41 > 0:31:45that would have surprised their predecessors,

0:31:45 > 0:31:50they began to notice a number of strange anomalies in the landscape.

0:31:50 > 0:31:53I've come here to the east coast of Scotland

0:31:53 > 0:31:54to a place called Siccar Point.

0:31:54 > 0:31:58It is wild, windy and rather beautiful.

0:31:58 > 0:32:02And just down there is something truly remarkable, something which an early

0:32:02 > 0:32:07geologist who came here described as like looking into the abyss of time.

0:32:24 > 0:32:28This is what I've come to see and it is very strange indeed.

0:32:28 > 0:32:31It's called an unconformity.

0:32:31 > 0:32:36What you have down there is layers of rock that appear to be laid down vertically.

0:32:36 > 0:32:43And then just above them a layer of red sandstone, which appears to have been laid down horizontally.

0:32:48 > 0:32:50But as odd as this may seem,

0:32:50 > 0:32:54to some there appeared to be a startling explanation.

0:32:57 > 0:33:01This layer of rock looks as though it was laid down vertically.

0:33:01 > 0:33:05But at some point in the past it must have been at the bottom of the ocean

0:33:05 > 0:33:09and formed horizontally by layer after layer of sediment.

0:33:09 > 0:33:12Then the whole thing rose to the surface, was flipped

0:33:12 > 0:33:16through 90 degrees and sank to the bottom of the seas again.

0:33:16 > 0:33:19There another layer formed,

0:33:19 > 0:33:24until finally the whole thing rose to the surface once again.

0:33:28 > 0:33:34All these processes are extremely slow and all this implied

0:33:34 > 0:33:38that the earth is incredibly old - practically eternal.

0:33:42 > 0:33:46And it wasn't just Siccar Point.

0:33:46 > 0:33:48The evidence for slow change was everywhere.

0:33:50 > 0:33:54Geologists looked at waterfalls and saw how the constant

0:33:54 > 0:33:58flow of water had gradually eroded the surrounding rock.

0:34:01 > 0:34:06They saw how rain had inexorably worn away the tops of mountains.

0:34:08 > 0:34:11And how the slow movement of glaciers

0:34:11 > 0:34:14had carved out entire valleys.

0:34:18 > 0:34:22They came to realize that the single most important factor

0:34:22 > 0:34:25in why the world looks the way it does

0:34:25 > 0:34:29was time and lots of it.

0:34:33 > 0:34:37The moment that people first began to think in terms of deep time

0:34:37 > 0:34:40is one of the most significant in the history of science.

0:34:40 > 0:34:44It would go on to profoundly affect how people see themselves.

0:34:44 > 0:34:49But trying to grasp deep time is extremely difficult, because it is so different to human time.

0:34:49 > 0:34:52So you have to rely on analogies.

0:34:52 > 0:34:59One of my favourites is to imagine the age of the earth as a length from my shoulder to my finger tips.

0:34:59 > 0:35:06On that scale, the whole of human history, everything we've achieved in the last few thousand years

0:35:06 > 0:35:11would be wiped away by the single swipe of a nail file.

0:35:13 > 0:35:17So, why did this concept of deep time take root now?

0:35:19 > 0:35:24There was the expansion of quarrying and mining exposing more of the hidden earth.

0:35:25 > 0:35:29The fossils of extinct creatures that were being uncovered.

0:35:31 > 0:35:36And the emergence of geology - a new scientific view of the planet.

0:35:39 > 0:35:45Finally, the pieces were in place to try and answer the question - how did WE get here?

0:35:52 > 0:35:58The industrial revolution was a time of rapid, dizzying change.

0:35:58 > 0:36:03Great industrial cities spread across Victorian Britain,

0:36:03 > 0:36:09their factories drawing in workers from far and wide.

0:36:09 > 0:36:14New railways snaked across the landscape cutting journey times

0:36:14 > 0:36:18and bringing cheap goods to the masses.

0:36:20 > 0:36:25'It was a whirlwind of new ideas, new methods

0:36:25 > 0:36:29'and all of it in the name of progress.'

0:36:31 > 0:36:36Belief in progress was one of the defining characteristics of the Victorian age.

0:36:36 > 0:36:42Factory owners from humble origins had country houses, even seats in Parliament.

0:36:42 > 0:36:48Britain was the leading industrial country in the world thanks to the ingenuity of her people.

0:36:57 > 0:37:00It was out of this belief in progress that a radical theory

0:37:00 > 0:37:04of how WE got here exploded onto the scene.

0:37:11 > 0:37:15The theory proposed that not only were societies and nations

0:37:15 > 0:37:19capable of progressive change, but also nature.

0:37:38 > 0:37:42In 1844, this slim, rather ordinary looking book was first published

0:37:42 > 0:37:46and it swiftly became one of THE most controversial books

0:37:46 > 0:37:48of the Victorian age.

0:37:48 > 0:37:52It was a literary sensation selling tens of thousands of copies

0:37:52 > 0:37:56and it was read by everyone of influence from the Queen downwards.

0:37:56 > 0:38:00Adding to its mystique was the fact that its author made strenuous

0:38:00 > 0:38:05efforts throughout his lifetime to remain strictly anonymous.

0:38:09 > 0:38:12The author was a Scotsman -

0:38:12 > 0:38:14Robert Chambers.

0:38:15 > 0:38:20Robert Chambers was born with six fingers and six toes.

0:38:20 > 0:38:23When was young he had an operation to get rid of the extra digits,

0:38:23 > 0:38:25which unfortunately went wrong.

0:38:25 > 0:38:30Self conscious, Robert now immersed himself in the world of print.

0:38:34 > 0:38:39Few changes embodied the Victorian ideal of progress

0:38:39 > 0:38:43as much as the 19th Century transformation of the print industry.

0:38:43 > 0:38:49The steam-powered printing press ushered in a new age of cheap,

0:38:49 > 0:38:53mass-produced books creating a hunger for knowledge right across society.

0:38:58 > 0:39:00In response to this demand,

0:39:00 > 0:39:05Robert Chambers helped his brother set up a successful publishing firm,

0:39:05 > 0:39:09while still leaving enough time to devote to his first love -

0:39:09 > 0:39:12writing.

0:39:12 > 0:39:17Robert Chambers was not a very original thinker but he was well read.

0:39:17 > 0:39:21His writing was clear, vivid and above all thought provoking.

0:39:21 > 0:39:26It was these qualities plus the fact that he had an insider's knowledge

0:39:26 > 0:39:31of the publishing industry, which ensured his book was a huge success.

0:39:31 > 0:39:37Chambers called it Vestiges Of The Natural History Of Creation

0:39:37 > 0:39:40and in it he presented a compelling case

0:39:40 > 0:39:45for the notion that species are not fixed - they change.

0:39:48 > 0:39:52That everything had developed from an earlier form.

0:39:53 > 0:39:56He called this concept transmutation.

0:39:56 > 0:40:00We call it evolution.

0:40:04 > 0:40:10Evolution emerged out of a world of progress, a conviction that

0:40:10 > 0:40:14all things are capable of change, of improvement.

0:40:14 > 0:40:20A history of life that was as diverse as it was baffling.

0:40:20 > 0:40:24And a realization that the earth was almost immeasurably old.

0:40:26 > 0:40:30But the real significance of evolution to this story is that

0:40:30 > 0:40:34it now forced people to confront the uncomfortable question -

0:40:34 > 0:40:36how did we get here?

0:40:39 > 0:40:42Chambers was not the first person to write about evolution,

0:40:42 > 0:40:45but he did take the argument further than others had.

0:40:45 > 0:40:48Instead of being set apart from the rest of creation,

0:40:48 > 0:40:52Chambers was saying we were simply an extension of it.

0:40:52 > 0:40:55No wonder he wanted to remain anonymous.

0:40:57 > 0:40:58SCREAMING

0:40:59 > 0:41:03For a society where people fervently believed that

0:41:03 > 0:41:06humans had a special place in God's creation,

0:41:06 > 0:41:11the claim we were descended from animals was deeply shocking.

0:41:12 > 0:41:15And so the backlash began.

0:41:16 > 0:41:19There were attacks from the scientific community

0:41:19 > 0:41:22on the book's accuracy.

0:41:22 > 0:41:28And from the clergy for undermining moral and social order.

0:41:30 > 0:41:33One particularly scathing review described it as,

0:41:33 > 0:41:37"not merely shallow and superficial, but utterly false throughout."

0:41:37 > 0:41:40Harsh. But despite the controversy,

0:41:40 > 0:41:42or let's face it probably because of it,

0:41:42 > 0:41:46the public simply couldn't get enough of this book.

0:41:49 > 0:41:53For all its success, what Chambers' book didn't do

0:41:53 > 0:41:57was come up with an explanation of how evolution happens.

0:42:01 > 0:42:06The man who answered that question was, of course, Charles Darwin.

0:42:10 > 0:42:14A keen geologist and an ardent believer in the earth's antiquity,

0:42:14 > 0:42:17Darwin had been working on his own theory of evolution

0:42:17 > 0:42:20for several years when Vestiges first appeared.

0:42:23 > 0:42:29But, it would be a further 15 years, by which time much of the fuss

0:42:29 > 0:42:34surrounding evolution had died down, before Darwin felt ready to publish.

0:42:43 > 0:42:47His explanation for how animals evolved had its roots in

0:42:47 > 0:42:52the same industrial landscape from which Chambers' book had emerged.

0:43:04 > 0:43:08According to Darwin, life was one long struggle for survival.

0:43:08 > 0:43:10And just as within the cotton industry,

0:43:10 > 0:43:13there was competition between manufacturers,

0:43:13 > 0:43:17so in nature there was competition between and amongst species.

0:43:19 > 0:43:24Just as new technology might give one factory an edge over another,

0:43:24 > 0:43:27so it was in nature.

0:43:29 > 0:43:35Any new trait that gave an organism an edge over its rival would prevail

0:43:35 > 0:43:39and become more common in later generations.

0:43:39 > 0:43:45Gradually giving rise to the appearance of new species.

0:43:48 > 0:43:54A mechanism for change that Darwin called Natural Selection.

0:43:57 > 0:44:02Darwin's followers must have hoped that his theory of Natural Selection

0:44:02 > 0:44:05would help answer the question - how did we get here?

0:44:05 > 0:44:07But there were holes in the theory.

0:44:07 > 0:44:13Although Darwin acknowledged the critical importance of the environment on driving evolution,

0:44:13 > 0:44:16he never fully grasped the incredible extent

0:44:16 > 0:44:20to which life on earth is shaped by changes in our violent planet.

0:44:20 > 0:44:24Something which has only relatively recently come to light.

0:44:30 > 0:44:34While biology raced ahead in the early 20th Century,

0:44:34 > 0:44:38geology had more or less settled into a routine.

0:44:38 > 0:44:40Stones were dated,

0:44:40 > 0:44:44fossils examined, collections expanded.

0:44:45 > 0:44:48But, as so often happens in the story of science,

0:44:48 > 0:44:53it's the non-specialists, the enthusiasts who shake things up.

0:44:54 > 0:44:57One such enthusiast was Alfred Wegener.

0:44:57 > 0:45:00He was a German meteorologist, a weather man,

0:45:00 > 0:45:03and with his brother, he held a world record for ballooning.

0:45:03 > 0:45:06He was not, however, a trained geologist.

0:45:06 > 0:45:09But that didn't put him off proposing a radical

0:45:09 > 0:45:14and controversial new theory about the forces that shaped the earth.

0:45:14 > 0:45:19Forces so powerful as to have shaped even life itself.

0:45:22 > 0:45:29The story goes the Wegner was looking at an atlas when he noticed something rather peculiar.

0:45:29 > 0:45:35Take a map of the world, a pair of scissors and cut your way down through Greenland

0:45:35 > 0:45:38until you get to the cost of South America.

0:45:38 > 0:45:41And then it requires a little bit more finesse

0:45:41 > 0:45:46working away carefully around Brazil.

0:45:46 > 0:45:49And then at the end, just slash away again.

0:45:49 > 0:45:52If you move the coast of South America over to the coast

0:45:52 > 0:45:58of Africa what you'll notice is that they seem to match very closely.

0:45:58 > 0:46:00It's almost as if they were once joined.

0:46:02 > 0:46:07Wegner noticed this, but he did nothing about it for around a year,

0:46:07 > 0:46:11until he came across some fascinating fossil finds.

0:46:20 > 0:46:22Take a look at this.

0:46:22 > 0:46:28It's a fossilized leaf and it's about 250 million years old.

0:46:28 > 0:46:31It came from a tree fern that is now extinct.

0:46:31 > 0:46:34Now, the odd thing these tree ferns grew in the tropics

0:46:34 > 0:46:40but these fossils have been found in cold, remote places like this one.

0:46:40 > 0:46:44In fact, places even colder than here in Iceland.

0:46:44 > 0:46:47So how was that possible?

0:46:49 > 0:46:52Then, there were reptiles.

0:46:52 > 0:46:55A particular species of reptile found in South America

0:46:55 > 0:47:02but mysteriously matched by exactly the same species in Africa more than 7,000 kms away.

0:47:05 > 0:47:12In attempting to explain these mysteries, Wegner would transform geology.

0:47:12 > 0:47:15Science would have to embrace a new

0:47:15 > 0:47:19and very different history of life on earth.

0:47:22 > 0:47:29Wegner developed a theory that was logical, but also, on the surface, completely ludicrous.

0:47:29 > 0:47:34He suggested that all the great seven continents had once been clumped together

0:47:34 > 0:47:39into a single super continent that he called Pangaea meaning, "all lands".

0:47:39 > 0:47:43And then Pangaea had simply split apart.

0:47:45 > 0:47:48A process that Wegner attempted to illustrate.

0:47:56 > 0:48:00Wegner compared the moving continents to the huge floating icebergs

0:48:00 > 0:48:04he'd seen on his many field trips to Greenland.

0:48:06 > 0:48:09But instead of blocks of ice weighing a few thousand tons,

0:48:09 > 0:48:16he was talking about great slabs of rock weighing trillions of tons.

0:48:16 > 0:48:21The problem for Wegner was nobody was buying his big idea.

0:48:22 > 0:48:27To his eternal frustration, Wegner had no way to explain

0:48:27 > 0:48:33how the slabs moved, no hard evidence to convince the sceptics.

0:48:33 > 0:48:39One of Wegner's many critics described his ideas as "utter, damned rot."

0:48:39 > 0:48:40And you can see why.

0:48:40 > 0:48:45The idea that we are floating around seems preposterous.

0:48:45 > 0:48:48And it didn't help that Wegner was an amateur geologist,

0:48:48 > 0:48:52in many eyes, a jumped-up weather forecaster.

0:48:54 > 0:48:59Wegner went back to meteorology and his theory was shelved

0:48:59 > 0:49:06until a series of unexpected discoveries made during the height of the Cold War.

0:49:10 > 0:49:15In the 1950s, as the Cold War intensified, the United States

0:49:15 > 0:49:22and the Soviet Union found themselves engaged in a game of cat and mouse deep beneath the ocean.

0:49:25 > 0:49:30A game that demanded a much more accurate picture of this underwater landscape.

0:49:33 > 0:49:38And so the oceanographers set to work.

0:49:40 > 0:49:44They began taking thousands of photographs of the ocean floor.

0:49:48 > 0:49:54Echo soundings plotted the rise and fall of deep sea ridges...

0:49:56 > 0:50:02..while drill rods were sent down to establish the composition of the sea bed.

0:50:04 > 0:50:11But, in mapping the oceans, the scientists discovered something entirely unexpected.

0:50:13 > 0:50:19They found that the sea floor didn't consists of one thick uniform crust,

0:50:19 > 0:50:24as used to be thought, but a number of thin interlocking plates.

0:50:26 > 0:50:31And that the boundaries to those plates featured mountain ranges...

0:50:34 > 0:50:37..deep rift valleys...

0:50:39 > 0:50:41..even volcanoes.

0:50:47 > 0:50:55And this entire landscape was floating on a bed of molten rock constantly on the move.

0:51:04 > 0:51:09And you can also see evidence of this on dry land.

0:51:12 > 0:51:16I've come to Thingvellir in Iceland, one of the wonders of the world.

0:51:16 > 0:51:19It is one of the few places on earth

0:51:19 > 0:51:21that you can actually see with your own eyes

0:51:21 > 0:51:24the joins in our patchwork planet.

0:51:42 > 0:51:48This may look like an ordinary cliff edge, but it's actually the start of an enormous great slab of rock

0:51:48 > 0:51:50which extends all the way from here in Iceland,

0:51:50 > 0:51:55across the Atlantic Ocean, across North America to the Pacific Ocean.

0:51:55 > 0:51:57It is called the North American Plate.

0:51:57 > 0:52:03And just over there, well, that is the beginning of another enormous plate.

0:52:03 > 0:52:09It is called the Eurasian Plate, and it extends all the way from here to Shanghai.

0:52:12 > 0:52:18Now, if I was to stand here long enough, say, a few thousand years,

0:52:18 > 0:52:25I'd notice the gap between me and Eurasia was getting wider.

0:52:25 > 0:52:27Scientists have measured this movement.

0:52:27 > 0:52:34It ranges from a very gradual seven millimetres a year here at Thingvellir,

0:52:34 > 0:52:38to almost ten centimetres a year elsewhere.

0:52:38 > 0:52:40Over hundreds of millions of years,

0:52:40 > 0:52:46this shifting of the earth's plates has transformed the face of our planet,

0:52:46 > 0:52:51a never-ending cycle of change that Wegner had called continental drift.

0:52:54 > 0:52:58Sadly, Wegner didn't live long enough to see his theory vindicated.

0:52:58 > 0:53:02In 1930, he went on an expedition to Greenland.

0:53:02 > 0:53:06There, in temperatures of minus 60, he died of cold and exhaustion.

0:53:06 > 0:53:09He was buried on the ice.

0:53:09 > 0:53:15Because of continental drift, his body is now two metres further away from home.

0:53:22 > 0:53:28But continental drift has done much more than shape the earth.

0:53:28 > 0:53:34By showing how a fossilised tree fern could travel all the way from the tropics to the ice,

0:53:34 > 0:53:42or why it is that a single species of reptile can be found on what are now two widely separated continents.

0:53:42 > 0:53:48The theory also takes us closer to solving the mystery of how we got here.

0:53:53 > 0:54:01And that's because when the earth moves in this way, the results can also be incredibly violent.

0:54:01 > 0:54:04When the earth's plates collide...

0:54:06 > 0:54:13..they can trigger volcanic eruptions so powerful as to block out the sun for months on end.

0:54:18 > 0:54:21As those same plates grind against each other,

0:54:21 > 0:54:26so they cause devastating earthquakes...

0:54:28 > 0:54:35..which themselves can spawn mega-tsunamis, that destroy everything in their way.

0:54:39 > 0:54:43While it's easy to imagine that all this violent upheaval

0:54:43 > 0:54:49brought with it nothing but death and destruction, the truth is very different.

0:54:49 > 0:54:53It's now clear that throughout our four and half billion year history,

0:54:53 > 0:54:59the balance of our planet has been absolutely central to the creation of new life.

0:55:05 > 0:55:11Because, every time our planet experiences violent change,

0:55:11 > 0:55:14a new opportunity for life opens up...

0:55:16 > 0:55:22..making continental drift one of the great drivers of evolution.

0:55:22 > 0:55:27And here are just a couple of ways it has changed life on earth.

0:55:29 > 0:55:31Some 30 million years ago,

0:55:31 > 0:55:37the plate boundary separating Africa from Arabia began to pull apart,

0:55:37 > 0:55:41causing the land in between to fall away.

0:55:44 > 0:55:46A 5,000 km gash in the earth's crust,

0:55:46 > 0:55:50that we know as the East African Rift Valley.

0:55:55 > 0:55:58As a new landscape of broken savannah formed,

0:55:58 > 0:56:05it allowed the ancestors of many today's animals to gain a foothold, and to flourish.

0:56:14 > 0:56:19And then there is climate change, when continental drift has also played a major role...

0:56:21 > 0:56:25..not least by accelerating the onset of ice ages,

0:56:25 > 0:56:30by pushing land towards the poles, and altering the flow of ocean currents.

0:56:35 > 0:56:40Changes which have forced animals to adapt in the most remarkable of ways.

0:56:42 > 0:56:48And, just occasionally, we're subjected to violence...

0:56:50 > 0:56:53..from beyond our planet,

0:56:53 > 0:56:59so extreme, that many species are wiped out altogether...

0:57:01 > 0:57:05..only for others to take their place.

0:57:11 > 0:57:15And so, what of us?

0:57:15 > 0:57:17How did we get here?

0:57:18 > 0:57:24Well, we are just the latest in a long line of lucky survivors,

0:57:24 > 0:57:29born out of death, destruction, and the immensity of deep time.

0:57:32 > 0:57:37And if this great experiment that is life on earth

0:57:37 > 0:57:38were to be run again...

0:57:44 > 0:57:46..we might never even show up.

0:57:53 > 0:57:58It's now clear that the story of life, and the story of our planet,

0:57:58 > 0:58:01which were once seen as separate, are actually intrinsically linked.

0:58:01 > 0:58:05The evolution of new life has been driven by climate change,

0:58:05 > 0:58:11by asteroid impacts, and by the slow-motion collision of continents.

0:58:11 > 0:58:16It turns out that we and every other living creature

0:58:16 > 0:58:20are marching to the drum beat of our violent planet.

0:58:40 > 0:58:45Next time, an ancient human ambition...

0:58:45 > 0:58:48the search for limitless power.

0:59:03 > 0:59:06Subtitles by Red Bee Media Ltd

0:59:06 > 0:59:09E-mail subtitling@bbc.co.uk