0:00:07 > 0:00:10I've spent most of my life trying to understand
0:00:10 > 0:00:12the forces that shaped our planet,
0:00:12 > 0:00:14and as a geologist, it always seemed to me
0:00:14 > 0:00:17that rocks were right at the heart of things.
0:00:21 > 0:00:26But now, I'm discovering it's not only volcanoes and colliding continents
0:00:26 > 0:00:29that have driven the Earth's greatest changes,
0:00:29 > 0:00:33because at crucial moments in its history,
0:00:33 > 0:00:36another force has helped create the planet we live on...
0:00:37 > 0:00:39...plants.
0:00:41 > 0:00:43It's a whole new story about the Earth,
0:00:43 > 0:00:47revealing how, from its earliest history,
0:00:47 > 0:00:49plants have shaped our world.
0:00:52 > 0:00:57So far, we've seen how plants and their ancestors began
0:00:57 > 0:00:59by producing our life-giving atmosphere.
0:00:59 > 0:01:04I'm breathing oxygen that was made two-and-a-half billion years ago.
0:01:05 > 0:01:09They'd harnessed light from the sun,
0:01:09 > 0:01:11bringing energy to the world.
0:01:11 > 0:01:14And they'd formed the fertile soil,
0:01:14 > 0:01:17allowing life to colonise the land.
0:01:26 > 0:01:30But the next chapter will take us even further,
0:01:30 > 0:01:34because a powerful newcomer to the plant world was on its way.
0:01:34 > 0:01:37It would conquer every corner of the planet.
0:01:37 > 0:01:41It would shape the very surface of the Earth
0:01:41 > 0:01:45and it would drive the evolution of animal life,
0:01:45 > 0:01:48including our own ancestors.
0:01:48 > 0:01:51This is its story.
0:02:10 > 0:02:14These buildings are nearly 1,000 years old.
0:02:15 > 0:02:18The largest religious site in the world,
0:02:18 > 0:02:21covering 200 square kilometres.
0:02:23 > 0:02:27This is the temple of Angkor Wat in Cambodia.
0:02:30 > 0:02:32I am here to witness the importance
0:02:32 > 0:02:36of one of the most powerful symbols known to humankind.
0:02:38 > 0:02:43A symbol central to an ancient Buddhist ceremony.
0:02:45 > 0:02:47Flowers.
0:02:48 > 0:02:50(BUDDHIST CHANTING)
0:02:54 > 0:03:00You see lotus flowers and jasmine just arranged beautifully up there.
0:03:00 > 0:03:04The lotus are the big ones and the jasmine the trail of little flowers.
0:03:04 > 0:03:09See how the lotus petals are all folded in amongst themselves,
0:03:09 > 0:03:13the different layers representing the various levels of heaven.
0:03:14 > 0:03:17For these monks, flowers have a crucial role.
0:03:19 > 0:03:23And this is just one ceremony from one religion.
0:03:23 > 0:03:27Flowers are central to cultures throughout the world.
0:03:28 > 0:03:31They're deeply woven into all our lives.
0:04:00 > 0:04:04But it's not only a human obsession.
0:04:04 > 0:04:06Because since they evolved,
0:04:06 > 0:04:10flowers have been the driving force for the whole of life on Earth.
0:04:14 > 0:04:16They've become enmeshed in the lives
0:04:16 > 0:04:21of virtually the entire animal kingdom in all its rich diversity.
0:04:21 > 0:04:24From the smallest insect to some of the largest mammals,
0:04:24 > 0:04:26they've all been shaped by flowers.
0:04:26 > 0:04:28But how did this happen?
0:04:28 > 0:04:31And why?
0:04:36 > 0:04:38The emergence of flowers
0:04:38 > 0:04:42is one of the biggest turning points in Earth's history.
0:04:42 > 0:04:45To understand how they changed our planet,
0:04:45 > 0:04:49we need to go right back to a prehistoric time...
0:04:52 > 0:04:55...to the moment when the very first flower appeared.
0:04:59 > 0:05:05Up until around 140 million years ago, the Earth was very different.
0:05:05 > 0:05:09The animal kingdom was dominated by dinosaurs.
0:05:10 > 0:05:14And the separate continents we know today didn't exist.
0:05:14 > 0:05:19Instead, there had been a single huge continent, Pangaea.
0:05:25 > 0:05:28I'm heading for a place that's about as close as you can get
0:05:28 > 0:05:30to that ancient supercontinent.
0:05:32 > 0:05:38It's in the remote South Pacific, 1,500km from Australia.
0:05:38 > 0:05:41The island of New Caledonia.
0:05:54 > 0:05:56It looks like Paradise, doesn't it?
0:05:56 > 0:06:00What makes New Caledonia just so interesting
0:06:00 > 0:06:03is that it's like a Noah's Ark of ancient plants.
0:06:03 > 0:06:08This little journey is going to take us back in time 140 million years.
0:06:15 > 0:06:19Because this part of the world is so isolated,
0:06:19 > 0:06:23it gives a glimpse of the plant world before flowers existed.
0:06:24 > 0:06:29Back then, the plant kingdom had two mighty rulers.
0:06:29 > 0:06:32One of them was the tall conifers,
0:06:32 > 0:06:34like this prehistoric species of pine.
0:06:39 > 0:06:42Look at these trees. Bizarre, aren't they?
0:06:42 > 0:06:44They're huge.
0:06:45 > 0:06:47Araucaria, Cook pine,
0:06:47 > 0:06:51named after Captain Cook who explored this corner of the world.
0:06:51 > 0:06:57Pine trees are a family of conifers that are amongst the oldest in the world
0:06:57 > 0:07:01so when the dinosaurs were around, these were nature's real giants.
0:07:02 > 0:07:05What made flowers so revolutionary
0:07:05 > 0:07:10was the limitations of the ancient plants that came before them.
0:07:11 > 0:07:17To reproduce, conifers like these relied on the vagaries of the wind.
0:07:22 > 0:07:26This is pollen, the male sex cells of conifers.
0:07:26 > 0:07:32Each grain has to be magnified 1,000 times to really see it.
0:07:34 > 0:07:38The two air sacs, one in each side, catch the breeze.
0:07:40 > 0:07:43With luck, the male pollen will be blown
0:07:43 > 0:07:46to a female cone on a nearby tree.
0:07:46 > 0:07:51But for that to happen, each conifer needs vast amounts.
0:07:53 > 0:07:55It's very wasteful.
0:07:55 > 0:08:00Up to 10 billion grains have to be released by a single tree.
0:08:05 > 0:08:08The other big player back then was the ferns.
0:08:10 > 0:08:15Their method of reproduction was also restricting.
0:08:17 > 0:08:20Because ferns evolved in wet, swampy conditions,
0:08:20 > 0:08:23they needed water to transport their sex cells.
0:08:25 > 0:08:28And they use a surprising device.
0:08:29 > 0:08:32What they do is they release a sperm,
0:08:32 > 0:08:35which swims through the water and mud to a nearby plant
0:08:35 > 0:08:37and fertilises the egg.
0:08:39 > 0:08:43Under a microscope, you can see that by thrashing around,
0:08:43 > 0:08:47the male sperm cell can propel itself through water.
0:08:48 > 0:08:51It's able to swim for over two hours.
0:08:53 > 0:08:55It's amazing to think that a plant
0:08:55 > 0:08:59produces something like a human sperm.
0:09:00 > 0:09:04But the downside was that ferns had to live near water.
0:09:04 > 0:09:06It was hugely limiting.
0:09:08 > 0:09:12All this meant something was lacking in the world of Pangaea...
0:09:15 > 0:09:16..diversity.
0:09:17 > 0:09:22There were few species of ferns and even fewer types of conifers.
0:09:24 > 0:09:28Just 1% of the range of plants we have today.
0:09:30 > 0:09:33And the animal kingdom was also limited.
0:09:38 > 0:09:42Scientists have found evidence of 700 different dinosaurs.
0:09:43 > 0:09:44It sounds a lot,
0:09:44 > 0:09:49but today there are over 5,500 species of mammals alone.
0:09:50 > 0:09:52There was little variety.
0:09:53 > 0:09:56It was a monotonous green world.
0:09:57 > 0:10:01And that's how life on the planet would have continued.
0:10:15 > 0:10:19140 million years ago, somewhere in Pangaea,
0:10:19 > 0:10:25one plant of one species happened to chance on a new way of reproducing.
0:10:27 > 0:10:30And it would change the Earth for ever.
0:10:35 > 0:10:38I've pushed further into New Caledonia's jungle.
0:10:46 > 0:10:52The plant I'm after is really rare, which is why I've come so far.
0:10:52 > 0:10:58This is the only place that you find it. It's died out everywhere else.
0:10:58 > 0:11:02Mind you, amongst all of this, it's like a needle in a haystack.
0:11:09 > 0:11:11Hang on a minute.
0:11:11 > 0:11:13That looks like the leaves.
0:11:15 > 0:11:16That wood.
0:11:17 > 0:11:18Got them.
0:11:20 > 0:11:23I've come all the way round the world to find that.
0:11:23 > 0:11:26That is the Amborella plant.
0:11:28 > 0:11:33Amborella trichopoda is the closest living relative
0:11:33 > 0:11:36of the first flower to evolve.
0:11:36 > 0:11:40All flowers today have descended from its ancestor.
0:11:48 > 0:11:52Botanists believe it began when a single plant mutated
0:11:52 > 0:11:56to have leaves that became petals which, instead of being green,
0:11:56 > 0:12:00were probably white like those of Amborella.
0:12:01 > 0:12:06We now consider them to be the very first petals of the very first flower.
0:12:07 > 0:12:12To grasp the significance of this plant, you have to imagine a scene
0:12:12 > 0:12:17in some primordial forest where everything's just completely green.
0:12:17 > 0:12:20And then there's this flash of colour and glint of white.
0:12:20 > 0:12:22Some chance mutation.
0:12:22 > 0:12:25And the thing is that scurrying amongst it is a little beetle.
0:12:25 > 0:12:28Certainly not a bee because bees hadn't evolved yet,
0:12:28 > 0:12:32but a beetle spies this dash of white and scurries across to have a look.
0:12:32 > 0:12:35And then munches on these little white buds
0:12:35 > 0:12:37that are just packed full of pollen.
0:12:39 > 0:12:42But not all the pollen is eaten.
0:12:42 > 0:12:47Some sticks to the beetle, and on it goes to other plants.
0:12:50 > 0:12:55Unknowingly, it's become a courier, delivering pollen from plant to plant,
0:12:55 > 0:12:58pollinating them as it looks for food.
0:13:05 > 0:13:09Plants had evolved an ingenious way of reproducing
0:13:09 > 0:13:11that no longer relied on haphazard methods,
0:13:11 > 0:13:14like the wind for conifers or water for ferns.
0:13:15 > 0:13:18Instead it was reliable.
0:13:18 > 0:13:22Insects carried pollen directly to other plants.
0:13:22 > 0:13:26It was the birth of flowers.
0:13:28 > 0:13:32It's hard to grasp just how revolutionary this was.
0:13:32 > 0:13:36I'm used to thinking of momentous changes in the Earth
0:13:36 > 0:13:38as occurring through huge events -
0:13:38 > 0:13:42vast continents colliding or mountains uplifting,
0:13:42 > 0:13:45but this was the tiniest of events.
0:13:45 > 0:13:47A subtle alteration of how a plant looked
0:13:47 > 0:13:51and a chance encounter with a curious beetle.
0:13:51 > 0:13:54And on the back of that, the world changed for ever.
0:14:04 > 0:14:08Back then, the supercontinent of Pangaea was splitting up.
0:14:10 > 0:14:12Smaller continents were forming...
0:14:15 > 0:14:17...creating countless new landscapes...
0:14:19 > 0:14:22..with new climates and environments -
0:14:22 > 0:14:24rising mountain ranges...
0:14:27 > 0:14:30..and dry inhospitable deserts.
0:14:31 > 0:14:36For conifers and ferns, so dependent on wind and water,
0:14:36 > 0:14:39the new landscapes were impregnable.
0:14:40 > 0:14:44But for flowering plants, it was the chance they'd been waiting for.
0:14:45 > 0:14:49Because they had a powerful in-built advantage.
0:14:56 > 0:14:58This is a monkey puzzle tree.
0:14:58 > 0:15:03Like most conifers, monkey puzzles live for hundreds of years,
0:15:03 > 0:15:08and crucially, they don't reach sexual maturity till they're 40.
0:15:09 > 0:15:13Now...this is a campion flower,
0:15:13 > 0:15:17which in the shadow of this thing looks pretty puny,
0:15:17 > 0:15:19but the campion flower has the last laugh
0:15:19 > 0:15:22because this, like most flowers, matures much quicker.
0:15:22 > 0:15:28In fact, the campion flower can reproduce after just four months.
0:15:28 > 0:15:30It means that in the time that it takes this conifer
0:15:30 > 0:15:32to produce just one generation,
0:15:32 > 0:15:36the flowers can go through 120 generations.
0:15:39 > 0:15:42What's so fascinating is the impact that this has got on evolution
0:15:42 > 0:15:44because every time there's a new generation,
0:15:44 > 0:15:48there's a possibility of a genetic mutation,
0:15:48 > 0:15:52a mutation that might give a characteristic that helps survival.
0:15:52 > 0:15:54So the faster the life cycles,
0:15:54 > 0:15:57the more species can adapt to new environments,
0:15:57 > 0:16:00which, of course, is crucial to our story.
0:16:11 > 0:16:15140 million years ago, these rapid life cycles
0:16:15 > 0:16:18helped flowers exploit the most hostile environments.
0:16:19 > 0:16:23Just like Tankwa Karoo in South Africa.
0:16:27 > 0:16:31Because beneath this desert is a hidden carpet of flowers.
0:16:32 > 0:16:36Each year, it rains for just two months.
0:16:37 > 0:16:41The plants only have this brief window to reproduce.
0:16:42 > 0:16:46So how do they ensure they are pollinated in time?
0:16:56 > 0:16:59They evolved colour.
0:17:08 > 0:17:11Each type of flower that you see is using colour
0:17:11 > 0:17:14in a struggle to get noticed by insects.
0:17:14 > 0:17:16And there isn't much time.
0:17:16 > 0:17:18In a few weeks or days the rains will be gone,
0:17:18 > 0:17:23and if these flowers aren't fertilised by then, the plants will die
0:17:23 > 0:17:26and the opportunity to reproduce will be lost.
0:17:27 > 0:17:32Hundreds of different flowers, dozens of different colours,
0:17:32 > 0:17:35whether it be orange gazanias,
0:17:35 > 0:17:37purple dew flowers,
0:17:37 > 0:17:40or the red balloon pea plant.
0:17:41 > 0:17:43And it wasn't random.
0:17:43 > 0:17:47Many used a different specific colour to attract insects.
0:17:49 > 0:17:51They became targets,
0:17:51 > 0:17:55using insects to transfer the right pollen to the right plant,
0:17:55 > 0:17:57even over great distances.
0:18:01 > 0:18:05And flowers evolved a clever way to enhance this colour.
0:18:08 > 0:18:11To the naked eye, a petal looks smooth.
0:18:11 > 0:18:16But magnify it 1,000 times and you can see its real structure.
0:18:23 > 0:18:26It's not a flat surface at all.
0:18:27 > 0:18:31Instead, the petal is made up of countless nodules.
0:18:32 > 0:18:38Each acts like a tiny prism, which reflects and diffracts light.
0:18:39 > 0:18:44It gives the petal an iridescence, to attract passing insects.
0:18:53 > 0:18:59And in their use of colour, flowers went even further.
0:19:23 > 0:19:25It's a heck of a contraption, isn't it?
0:19:25 > 0:19:28A special camera to give you a kind of...
0:19:28 > 0:19:31insect's view of what a flower looks like.
0:19:36 > 0:19:38That's nice. Look at that.
0:19:38 > 0:19:40Insects and this camera
0:19:40 > 0:19:44can see a part of the light spectrum called ultraviolet
0:19:44 > 0:19:47that's normally invisible to us humans.
0:19:59 > 0:20:03The camera reveals how flowers that appear plain to us
0:20:03 > 0:20:06look completely different to insects
0:20:11 > 0:20:14And the markings are really important
0:20:14 > 0:20:17because they are like airport runway lights
0:20:17 > 0:20:19that guide the insect down onto the petals.
0:20:21 > 0:20:24Like neon signs that say "free food here".
0:20:33 > 0:20:38But once the flowers were pollinated, they still faced a big challenge
0:20:38 > 0:20:43because their offspring then had to make it through the rest of the year.
0:20:45 > 0:20:49Here in the Karoo, that could be ten months of drought.
0:20:50 > 0:20:54To survive, flowers perfected another trick,
0:20:54 > 0:20:57which had a powerful impact on life on Earth.
0:20:59 > 0:21:00Seeds.
0:21:01 > 0:21:04Because seeds have this remarkable ability
0:21:04 > 0:21:06that we don't normally think about.
0:21:08 > 0:21:12These are seeds of the Canna indica flower, and this...
0:21:12 > 0:21:15This is an empty shotgun cartridge.
0:21:16 > 0:21:19I'm going to pack the seeds in where the lead pellets would have been.
0:21:29 > 0:21:31(GUNSHOTS)
0:21:36 > 0:21:39(BANG)
0:21:46 > 0:21:48Oh! It's gone right through.
0:21:50 > 0:21:52Look at that!
0:21:53 > 0:21:55That looks perfectly intact.
0:21:57 > 0:22:02The story goes that during the Indian Mutiny of the 19th century...
0:22:02 > 0:22:07soldiers used these seeds instead of lead shot.
0:22:13 > 0:22:17They're hard enough to be blasted out of a barrel and through wood.
0:22:20 > 0:22:22These seeds are so tough, in fact,
0:22:22 > 0:22:28that it's said that despite being fired from a gun, they can still germinate.
0:22:28 > 0:22:30Sounds unlikely, I know,
0:22:30 > 0:22:32though we'll see.
0:22:34 > 0:22:39But a tough shell wasn't all, because seeds from flowering plants
0:22:39 > 0:22:41developed a further evolutionary advantage
0:22:41 > 0:22:43that no other plant possessed.
0:22:51 > 0:22:54It all starts at the moment of pollination.
0:22:57 > 0:22:59Having been delivered by an insect,
0:22:59 > 0:23:03two cells from the pollen burrow deep into the flower's ovary.
0:23:06 > 0:23:11Here, one fertilises an egg to create an embryonic plant.
0:23:15 > 0:23:17But, and here's the clever bit,
0:23:17 > 0:23:22the second cell from the pollen does a completely different job.
0:23:22 > 0:23:24Instead of becoming a new plant,
0:23:24 > 0:23:28it grows into a food source for the fertilised egg.
0:23:28 > 0:23:31A kind of packed lunch.
0:23:31 > 0:23:34It's called double fertilisation
0:23:34 > 0:23:37and it's unique to the seeds of flowers.
0:23:45 > 0:23:48It meant seeds could lie dormant for months or even years
0:23:48 > 0:23:50until conditions were right.
0:23:54 > 0:23:59As for my Canna indica seeds, well, this is how they fared.
0:23:59 > 0:24:04Despite being blasted from a shotgun,
0:24:04 > 0:24:06four weeks later, here they are now...
0:24:07 > 0:24:12..successfully germinating into a tiny flowering plant.
0:24:13 > 0:24:14Remarkable!
0:24:18 > 0:24:20By 100 million years ago,
0:24:20 > 0:24:25flowers were redrawing the global map of where plants could live.
0:24:27 > 0:24:32They were turning once infertile areas into oases of life.
0:24:38 > 0:24:41And it wasn't just about plants.
0:24:41 > 0:24:47Because these flower oases were now luring animals, too.
0:24:47 > 0:24:52There was one ability above all that gave flowers the power to do this.
0:24:54 > 0:24:56Plants can do something unique
0:24:56 > 0:24:59that marks them out amongst all other living things on the planet.
0:24:59 > 0:25:04Their leaves can capture energy from our nearest star, the sun,
0:25:04 > 0:25:06and turn it into food.
0:25:09 > 0:25:15And the total amount of energy photosynthesis brings to the Earth
0:25:15 > 0:25:16is staggering.
0:25:32 > 0:25:34I know this is a bit odd,
0:25:34 > 0:25:38but just imagine that this little scooter and all the fuel that it uses
0:25:38 > 0:25:42represents all the energy that the USA consumes in just one year.
0:25:44 > 0:25:47Now imagine that you take all the plants in the world,
0:25:47 > 0:25:49all the trees, flowers and grasses...
0:25:51 > 0:25:53..all the jungles, forests and savannas
0:25:53 > 0:25:55and you add up the total energy
0:25:55 > 0:25:57harnessed by plants from the sun every year.
0:26:00 > 0:26:03It's not two scooters' worth or ten.
0:26:03 > 0:26:05It's all of this.
0:26:05 > 0:26:0940 times the amount of energy consumed by America every year.
0:26:15 > 0:26:20It's 100 trillion watts of energy every year.
0:26:21 > 0:26:27Astonishing as this is, flowers took all this energy and went even further.
0:26:28 > 0:26:31An adaptation that would have enormous repercussions
0:26:31 > 0:26:33for the animal kingdom.
0:26:33 > 0:26:36They developed this ingenious method
0:26:36 > 0:26:39of making the sugars available to their pollinators,
0:26:39 > 0:26:44and if I take this syringe here and just slide it delicately in here...
0:26:45 > 0:26:48..I can show you what they came up with.
0:26:53 > 0:26:57It's this really sweet-tasting liquid, nectar, of course.
0:26:57 > 0:27:00One of the most energetic sources of food on the planet
0:27:00 > 0:27:04and something animals found utterly irresistible.
0:27:05 > 0:27:08The nectar from this bird of paradise flower
0:27:08 > 0:27:12has three times the sugar concentration of Coca-Cola.
0:27:17 > 0:27:22Flowers were now pumping bite-sized packets of liquid energy
0:27:22 > 0:27:24into the food chain.
0:27:25 > 0:27:29And this began driving the evolution of entirely new insects.
0:27:33 > 0:27:35Just take a look at this.
0:27:35 > 0:27:37Isn't it beautiful?
0:27:37 > 0:27:42For me, this is one of the most incredible fossils ever found.
0:27:42 > 0:27:44It's such intricate detail.
0:27:44 > 0:27:46The material is amber.
0:27:46 > 0:27:48And inside it is a bee.
0:27:53 > 0:27:59It's a very primitive bee that got stuck in liquid tree resin
0:27:59 > 0:28:03which then solidified and preserved the hapless insect.
0:28:07 > 0:28:12Bee fossils like these began appearing roughly 100 million years ago.
0:28:13 > 0:28:16And what they show is the incredible impact
0:28:16 > 0:28:20flowering plants were now having on evolution.
0:28:21 > 0:28:26What I love about this fossil is that it's like a snapshot of an ancient past,
0:28:26 > 0:28:27just captured in time.
0:28:27 > 0:28:31And it makes you realise that there was a particular point
0:28:31 > 0:28:33when bees first arrived on Earth.
0:28:35 > 0:28:37Bees evolved from carnivorous wasps
0:28:37 > 0:28:42which had turned their backs on meat in favour of pollen and nectar.
0:28:45 > 0:28:48As they evolved, their whole bodies became covered in hair,
0:28:48 > 0:28:50to collect more pollen.
0:28:53 > 0:28:56They developed sophisticated compound eyes,
0:28:56 > 0:29:00with hundreds of tiny lenses to spot the flowers.
0:29:03 > 0:29:07Inside were special cells to detect UV light.
0:29:09 > 0:29:12There are more types of early bees in South Africa
0:29:12 > 0:29:16than anywhere else in the world so it's thought they originated here.
0:29:16 > 0:29:17And if you think about it,
0:29:17 > 0:29:21without the power of flowers, you'd have no bees at all.
0:29:23 > 0:29:27But by creating insects to pollinate them,
0:29:27 > 0:29:31the flowers introduced a new problem for themselves.
0:29:32 > 0:29:36There was a risk that after an insect picked up pollen from a flower,
0:29:36 > 0:29:41it would then travel on to a different species of flower and fail to fertilise it
0:29:42 > 0:29:44The pollen would be wasted.
0:29:46 > 0:29:49The solution of flowers was inspired.
0:29:51 > 0:29:55Down under these cliffs on the South African coast,
0:29:55 > 0:29:57you can see what they came up with.
0:30:00 > 0:30:04This lovely pink flower is Orphium frutescens...
0:30:05 > 0:30:08..which flourishes here in these salty conditions near the sea,
0:30:08 > 0:30:10but what's truly amazing about this plant
0:30:10 > 0:30:14is that it's struck up this exclusive relationship with a particular bee.
0:30:16 > 0:30:19Orphium flowers don't contain nectar.
0:30:19 > 0:30:22The payment they provide is pollen.
0:30:22 > 0:30:25But strangely, they keep it locked up.
0:30:25 > 0:30:29Special twisted stamens stop it being stolen by visiting insects.
0:30:29 > 0:30:33All, that is, except one -
0:30:33 > 0:30:35the female carpenter bee.
0:30:35 > 0:30:38Only she has the key.
0:30:40 > 0:30:45Let me show you what the bee has to do, using these tuning forks here.
0:30:45 > 0:30:47When the bee lands on the flower,
0:30:47 > 0:30:52it changes the rate at which it beats its wings to just the right frequency.
0:30:52 > 0:30:53From this note...
0:30:53 > 0:30:55(HIGH NOTE)
0:30:56 > 0:30:57..to this one.
0:30:57 > 0:30:59(LOWER NOTE)
0:31:00 > 0:31:02Middle C.
0:31:02 > 0:31:06And it's these vibrations that are the key to unlocking the stamens
0:31:06 > 0:31:12which open up at the top here and just shower the bee with pollen.
0:31:12 > 0:31:13(TUNING FORK BUZZES)
0:31:13 > 0:31:15Ah! Look at that.
0:31:15 > 0:31:18Look at the amount of yellow pollen on there. Fantastic!
0:31:20 > 0:31:22(BEE BUZZES)
0:31:22 > 0:31:25Now watch the bee do the same,
0:31:25 > 0:31:27hitting the middle C note...
0:31:27 > 0:31:28(BUZZING DROPS)
0:31:28 > 0:31:31..with the beat of its wings...
0:31:32 > 0:31:34..and unlocking the pollen.
0:31:35 > 0:31:38No other insect does this.
0:31:38 > 0:31:40It's incredible, isn't it?
0:31:40 > 0:31:44One single species of flower, one particular type of bee
0:31:44 > 0:31:48have evolved together to give this intimate partnership.
0:31:50 > 0:31:55It ensured that a flower's pollen was successfully taken
0:31:55 > 0:31:57to a plant of the same species.
0:32:00 > 0:32:02But these increasingly tight relationships
0:32:02 > 0:32:06between insects and flowers had another impact on life on Earth.
0:32:06 > 0:32:10Because they led to tighter and more isolated populations,
0:32:10 > 0:32:14that started creating gaps in the overall ecosystem.
0:32:14 > 0:32:20This, in turn, encouraged new species to evolve, filling in those spaces.
0:32:22 > 0:32:27Flowers were now driving a huge increase in the diversity of life.
0:32:28 > 0:32:33And they were fuelling this increase by pumping nectar into the food chain.
0:32:38 > 0:32:44The insects, bees, butterflies and moths, such as the hawk moth,
0:32:44 > 0:32:47were eating it with long, probing tongues.
0:32:49 > 0:32:54There were new species of birds, like the Calliope hummingbird,
0:32:54 > 0:32:56with beaks perfect for trumpet-shaped flowers.
0:32:59 > 0:33:03And predators, such as these toucans, that ate the pollinators.
0:33:04 > 0:33:08Between 120 and about 90 million years ago,
0:33:08 > 0:33:10all thanks to flowering plants,
0:33:10 > 0:33:16evolution had entered the most explosive phase in the Earth's history.
0:33:27 > 0:33:29By now Pangaea had split up,
0:33:29 > 0:33:33creating the continents so familiar to us today,
0:33:33 > 0:33:36and flowers dominated them.
0:33:37 > 0:33:41They'd conquered the ancient conifers and ferns, and covered half the Earth.
0:33:46 > 0:33:49But it wasn't just life they were changing.
0:33:50 > 0:33:54Because they started altering the very shape of the planet itself.
0:34:01 > 0:34:04This is Ha Long Bay in Vietnam.
0:34:04 > 0:34:08I'm here because it's evidence of how flowers unleashed
0:34:08 > 0:34:11some of the most powerful forces on Earth.
0:34:12 > 0:34:15This whole landscape just dwarfs you.
0:34:15 > 0:34:20You can see these pinnacles of limestone just soaring upwards,
0:34:20 > 0:34:22limestone that you get all over Vietnam.
0:34:22 > 0:34:28And it gives this really distinctive, even iconic landscape called karst.
0:34:28 > 0:34:31The thing is, when you look at things as huge as that
0:34:31 > 0:34:35you look for huge geological processes to create them,
0:34:35 > 0:34:37but it's not always the case.
0:34:42 > 0:34:44That's because 90 million years ago,
0:34:44 > 0:34:47flowers began to build an empire across the planet...
0:34:50 > 0:34:53..in a totally unexpected way.
0:34:57 > 0:35:01They did it by creating vast tropical rainforests.
0:35:14 > 0:35:18Almost all the trees are really giant flowering plants.
0:35:18 > 0:35:21You can see one here in flower.
0:35:21 > 0:35:25And all the trees are doing one thing.
0:35:31 > 0:35:33Breathe out on a piece of glass
0:35:33 > 0:35:36and it's pretty obvious that there's moisture in your breath.
0:35:36 > 0:35:39And in a funny kind of way, plants are breathing out moisture too.
0:35:39 > 0:35:41It's just much harder to see.
0:35:44 > 0:35:49But take a look at this. If I tie a clear plastic bag over this big leaf,
0:35:49 > 0:35:55then we should be able to actually see the plant breathing away.
0:35:55 > 0:35:59And all we need to do now is... wait a couple of hours.
0:36:07 > 0:36:10Look how much moisture this single banana leaf produces.
0:36:14 > 0:36:17It's losing water, or transpiring,
0:36:17 > 0:36:21through tiny pores in the leaf called stomata.
0:36:24 > 0:36:27Close up, you can see the veins of the leaf,
0:36:27 > 0:36:30which transport water around the plant.
0:36:31 > 0:36:35Leaves of flowering plants contain four times more veins
0:36:35 > 0:36:36than other plants.
0:36:43 > 0:36:46Because they share the same type of special vein leaves,
0:36:46 > 0:36:50trees like these act as kind of giant water pumps
0:36:50 > 0:36:54drawing moisture up from the soil and pumping it into the atmosphere.
0:36:54 > 0:36:58Some of these trees chuck out five tonnes of water every day.
0:37:07 > 0:37:11All this transpiration meant that 90 million years ago,
0:37:11 > 0:37:15flowering plants were creating more clouds...
0:37:19 > 0:37:21..which led to more rain.
0:37:21 > 0:37:23(THUNDER CRACKS)
0:37:24 > 0:37:26Water that, when it fell,
0:37:26 > 0:37:30was then drawn up from the forest floor by the same trees,
0:37:30 > 0:37:35forming a self-sustaining cycle of almost perpetual rainfall.
0:37:37 > 0:37:41In fact, 80% of the water in the rainforests
0:37:41 > 0:37:44came from the flowering plants themselves.
0:37:47 > 0:37:49In this new age of rain,
0:37:49 > 0:37:53water became an ever powerful sculpting force.
0:37:56 > 0:38:01And today, you can see its effects in an astonishing hidden world.
0:38:15 > 0:38:19Deep beneath the rainforest in central Vietnam
0:38:19 > 0:38:21are the caverns of Hang Son Doong.
0:38:23 > 0:38:27We are the first British film crew to explore them.
0:38:32 > 0:38:37Hang Son Doong is the largest cave passage ever discovered
0:38:37 > 0:38:39anywhere on Earth.
0:39:04 > 0:39:08This single cavern is nearly two kilometres long.
0:39:09 > 0:39:14All carved from solid rock by nothing more than water.
0:39:22 > 0:39:25All of which has trickled down from a single source -
0:39:25 > 0:39:28the vast jungle above.
0:39:30 > 0:39:34It is a relentless force that has carved out a dozen enormous caverns.
0:39:37 > 0:39:41An underground monument to the power of flowering plants.
0:39:51 > 0:39:55And deep in this labyrinth is what, for me, is perhaps the greatest
0:39:55 > 0:39:58of all the wonders of the plant world.
0:40:08 > 0:40:14Here, at the heart of the cave, a whole rainforest.
0:40:24 > 0:40:26Where the roof has collapsed,
0:40:26 > 0:40:29flowering plants have made their home...
0:40:33 > 0:40:36..200 metres below ground level.
0:40:40 > 0:40:42It is like a lost world.
0:40:42 > 0:40:48The thing is, just a few minutes ago, there was me in a cool, dark cave,
0:40:48 > 0:40:52and then ejected into this place with streaming sunlight.
0:40:52 > 0:40:55Hot and sticky rainforest.
0:40:57 > 0:41:01And where there's water and light, flowers have produced life.
0:41:13 > 0:41:16Plants such as this banana flower thrive,
0:41:16 > 0:41:19which in turn attracts butterflies and other animals.
0:41:22 > 0:41:25It's a thriving ecosystem here.
0:41:25 > 0:41:27And the whole thing is fed, really,
0:41:27 > 0:41:31everything, this whole food chain, is fed by the flowering plants.
0:41:36 > 0:41:40Flowering plants have created a small but perfect version
0:41:40 > 0:41:42of the rainforest above.
0:41:49 > 0:41:51Look at that mist.
0:41:51 > 0:41:54There's a whole weird microclimate in here.
0:41:54 > 0:41:57Clouds of moisture envelope everything.
0:41:57 > 0:42:00And the plants just soak up that moisture,
0:42:00 > 0:42:03just draw it up and then pass it out.
0:42:03 > 0:42:05So that cycle of transpiration
0:42:05 > 0:42:08that we see on a big scale up in the tropical forests
0:42:08 > 0:42:10is captured in miniature down here.
0:42:15 > 0:42:19Caves formed under all the world's great rainforests.
0:42:20 > 0:42:25And this extra water even began to transform the global climate.
0:42:28 > 0:42:32As water evaporates, it absorbs heat and cools the planet.
0:42:33 > 0:42:39The Amazon rainforest alone keeps its whole region five degrees colder.
0:42:39 > 0:42:43Across the planet, water injected into the water cycle
0:42:43 > 0:42:46was eroding deep canyons,
0:42:46 > 0:42:48carving high mountains,
0:42:48 > 0:42:52and sculpting the karst towers so iconic of Asia.
0:42:56 > 0:42:59It's extraordinary, isn't it?
0:42:59 > 0:43:01Especially when you think that all this
0:43:01 > 0:43:04comes not from huge forces deep underground,
0:43:04 > 0:43:09but in part from tiny changes on the leaves of flowering plants.
0:43:15 > 0:43:2065 million years ago was the age of the rainforests.
0:43:22 > 0:43:25They'd spread from the equator to cover most of the Earth.
0:43:26 > 0:43:32It meant three quarters of all plants were now flowers.
0:43:32 > 0:43:36A rich, lush home for millions of new animals.
0:43:38 > 0:43:43The dominance of the flowering plants seemed unassailable.
0:43:43 > 0:43:45But it was not to last.
0:43:51 > 0:43:58A 10km-wide asteroid coming from deep space was on a collision course.
0:44:06 > 0:44:10It hit the Earth with a force of a billion Hiroshima bombs.
0:44:10 > 0:44:1670 billion tonnes of pulverised rock were blasted into a low orbit.
0:44:20 > 0:44:25Scientists called it ejector and travelling at supersonic speeds
0:44:25 > 0:44:29its friction with the atmosphere heated the Earth up
0:44:29 > 0:44:31by over 200 degrees Celsius.
0:44:33 > 0:44:37It spontaneously triggered fires across the land.
0:44:42 > 0:44:47It was one of the worst mass extinctions in the history of the Earth.
0:44:50 > 0:44:53And famously killed off the dinosaurs.
0:45:01 > 0:45:05But less well known is the immediate impact on plants.
0:45:08 > 0:45:10Scientists believe that for them,
0:45:10 > 0:45:14the effect of the asteroid was also devastating.
0:45:16 > 0:45:19Not only were there fires,
0:45:19 > 0:45:23but the ejector created clouds of nitric and sulphur dioxide...
0:45:25 > 0:45:29..which fell as acid rain...
0:45:31 > 0:45:34..destroying plants from the roots up.
0:45:50 > 0:45:52I think it's really hard to imagine
0:45:52 > 0:45:55what the most recent and powerful extinction event must've been like,
0:45:55 > 0:45:59but perhaps the closest you can get to it is a newly-erupted volcano,
0:45:59 > 0:46:01like here in White Island, New Zealand.
0:46:04 > 0:46:06I think it's just the desolation, really.
0:46:07 > 0:46:12The bleakness, that sense that life's just been...obliterated.
0:46:15 > 0:46:17For plants,
0:46:17 > 0:46:21the aftermath of the asteroid impact must have been similar.
0:46:21 > 0:46:22Here on White Island,
0:46:22 > 0:46:25vegetation has been incinerated by successive eruptions.
0:46:27 > 0:46:32And the volcanic fumes create acid rain, just like after the asteroid.
0:46:34 > 0:46:36For flowering plants, it was a disaster.
0:46:36 > 0:46:39That close, almost inseparable relationship with insects
0:46:39 > 0:46:41was now their Achilles heel,
0:46:41 > 0:46:45because even if a flowering plant had survived the initial calamity,
0:46:45 > 0:46:48it needed a specific animal to pollinate it,
0:46:48 > 0:46:51and often they'd simply been wiped out.
0:47:01 > 0:47:03But flowers weren't beaten yet.
0:47:04 > 0:47:07All those evolutionary devices
0:47:07 > 0:47:10that had allowed them to thrive on a hostile planet in the first place
0:47:10 > 0:47:14now became their ultimate tools for survival.
0:47:16 > 0:47:20Coloured petals to attract the few surviving pollinators.
0:47:21 > 0:47:25Nectar to repay them in desperate times.
0:47:27 > 0:47:32Above all, flowers could rely on those superb survival capsules
0:47:32 > 0:47:36that could have been purpose-built for just such an apocalypse...
0:47:37 > 0:47:38..seeds.
0:47:48 > 0:47:51Now, following the asteroid impact,
0:47:51 > 0:47:54seeds helped flowers to re-colonise the Earth.
0:47:55 > 0:47:57And as they did so,
0:47:57 > 0:48:02once again flowers formed an inseparable relationship with animals.
0:48:02 > 0:48:09The dinosaurs had gone, but another type of animal had replaced them...
0:48:09 > 0:48:10..mammals.
0:48:15 > 0:48:18This time, flowers used mammals to help them distribute their seeds.
0:48:28 > 0:48:32Here in Thailand, this whole floating market celebrates
0:48:32 > 0:48:36the clever evolutionary device flowers came up with.
0:48:37 > 0:48:41More sophisticated flowers developed a really sneaky way
0:48:41 > 0:48:43of spreading their seeds.
0:48:43 > 0:48:47A method that didn't just disperse at metres, but kilometres.
0:48:47 > 0:48:50And to do that, they again harnessed the hunger of animals.
0:48:50 > 0:48:52They developed fruit.
0:48:58 > 0:48:59What is that?
0:48:59 > 0:49:01- Durian.- This is durian?
0:49:01 > 0:49:04- I cut. You taste.- OK, yeah.
0:49:05 > 0:49:09You can't come to Asia without trying the smelliest,
0:49:09 > 0:49:12most notorious fruit on Earth.
0:49:12 > 0:49:13Beautiful!
0:49:14 > 0:49:17I hope it tastes better than it smells, though.
0:49:18 > 0:49:21Ah! There's the seeds in there.
0:49:22 > 0:49:24And then this flesh.
0:49:24 > 0:49:26Texture's...
0:49:28 > 0:49:31THEY LAUGH
0:49:31 > 0:49:33They're all laughing. They're laughing.
0:49:33 > 0:49:36It's like an off avocado, really.
0:49:37 > 0:49:40I think that's what they call an acquired taste.
0:49:41 > 0:49:44The botanical definition of a fruit
0:49:44 > 0:49:48is that it must actually develop from the flower itself.
0:49:49 > 0:49:54The fleshy coating was once the ovary, as it grew around the maturing seeds.
0:49:54 > 0:49:57Lovely. Incredibly sweet.
0:49:57 > 0:49:59Very subtle.
0:50:00 > 0:50:04Isn't that great? The way all of them hide this inside, this little seed.
0:50:06 > 0:50:09You can see why some warm-blooded mammal or bird
0:50:09 > 0:50:12would want to eat this - it's just packed with nutrition.
0:50:12 > 0:50:14And of course, as you do that...
0:50:14 > 0:50:16you...
0:50:16 > 0:50:18you swallow the seed.
0:50:19 > 0:50:23And then later on you pass that out somewhere, miles away,
0:50:23 > 0:50:26dumped in some little dollop of manure.
0:50:26 > 0:50:29But that's really the point of all of these different types.
0:50:29 > 0:50:33All this diversity is designed to attract animals to eat it.
0:50:45 > 0:50:50Fruit is one of the most remarkable transformations in nature.
0:50:52 > 0:50:56What begins as an advertisement for an insect, a flower,
0:50:56 > 0:51:00becomes a protective covering for the seeds inside.
0:51:02 > 0:51:08And then a final burst... swells into the juicy flesh of a fruit.
0:51:24 > 0:51:2955 million years ago, one group of early mammals was evolving
0:51:29 > 0:51:32that relied almost entirely on fruit.
0:51:32 > 0:51:37In fact, without it, they'd probably never have existed.
0:51:42 > 0:51:48It was an animal which would directly link flowers to our human story.
0:51:52 > 0:51:56They live here in Thailand's Khao Sok National Park.
0:51:56 > 0:52:00Somewhere in these trees there are primates.
0:52:00 > 0:52:02GIBBONS CALLING
0:52:02 > 0:52:04I'm sure they're up there.
0:52:04 > 0:52:07You see the trees just... The branches moving but...
0:52:07 > 0:52:13trying to pinpoint the actual gibbons is...really tricky.
0:52:13 > 0:52:14Oh, there's one.
0:52:16 > 0:52:20Do you see it? It's kind of silhouetted in the branches just up there.
0:52:22 > 0:52:25I'm sure it... Yeah, it's moving.
0:52:25 > 0:52:28My first gibbon.
0:52:29 > 0:52:32The primates - lemurs, monkeys and apes -
0:52:32 > 0:52:36evolved an inseparable partnership with the fruit from flowers.
0:52:36 > 0:52:40And it determined their whole anatomy.
0:52:40 > 0:52:43Primates have got the perfect tools for reaching fruit.
0:52:43 > 0:52:45They've got these really strong hands which,
0:52:45 > 0:52:49along with their powerful chest and shoulder muscles,
0:52:49 > 0:52:51allow them to get up into the trees.
0:52:52 > 0:52:58All these are important traits that we human primates have inherited today.
0:52:59 > 0:53:01And all came from the need
0:53:01 > 0:53:05for the first primates to reach the fruit of flowering plants.
0:53:10 > 0:53:13Norberto Asensio is a primatologist.
0:53:13 > 0:53:18He studies the crucial role fruit plays in the diet of monkeys.
0:53:20 > 0:53:25For most primates, fruit is important. It's part of their diet - so what?
0:53:25 > 0:53:28Is it the core of the diet? The essential core, do you think?
0:53:28 > 0:53:29I would say so.
0:53:29 > 0:53:35I would say that most of the primates will have 70% to 90% of their diet
0:53:35 > 0:53:36- on fruit.- It's quite a lot.
0:53:37 > 0:53:43But back then, flowering plants created a problem for themselves.
0:53:43 > 0:53:45Primates were so hungry for fruit...
0:53:47 > 0:53:51..they would pick it long before the seeds inside were mature.
0:53:52 > 0:53:54It meant seeds were being wasted.
0:53:57 > 0:54:00So flowers came up with a solution.
0:54:06 > 0:54:12When fruit was ripe, they made it sweet, juicy and brightly coloured.
0:54:12 > 0:54:14It was a colour-coded time delay.
0:54:15 > 0:54:21And it encouraged primates to take only fruit that was fully mature.
0:54:23 > 0:54:26Norberto studies how this colour coding
0:54:26 > 0:54:30drove changes in our ancient ancestors.
0:54:30 > 0:54:35Before now, primates, like all mammals, were colour-blind.
0:54:36 > 0:54:41This made spotting ripe fruit difficult, as I'm about to find out.
0:54:41 > 0:54:43Let's do an experiment.
0:54:43 > 0:54:49Here you have glasses that are going to turn you into a simple mammal.
0:54:49 > 0:54:51Let's see.
0:54:51 > 0:54:52Oh, gosh!
0:54:53 > 0:54:58The glasses simulate colour blindness by removing red from the picture.
0:54:59 > 0:55:02I can kind of tell the difference in contrast between some of them.
0:55:02 > 0:55:07That's gone a very funny shade of bluishness.
0:55:07 > 0:55:09The interesting ones are these reds.
0:55:09 > 0:55:12I know they're red but they just don't seem red at all.
0:55:12 > 0:55:18Overall it's just got a very... almost bland greyness to it all.
0:55:23 > 0:55:25For primates to perceive red,
0:55:25 > 0:55:28they had to evolve a more sophisticated vision system.
0:55:32 > 0:55:36In the retina are special photo receptor cells that detect colour,
0:55:36 > 0:55:38called cones.
0:55:39 > 0:55:43There are 150,000 per square mm.
0:55:44 > 0:55:49Early mammals only had two types of cone, one for green and one for blue.
0:55:50 > 0:55:52It meant they were colour-blind.
0:55:52 > 0:55:55But primates evolved a third type.
0:55:55 > 0:55:59It was sensitive to red.
0:56:00 > 0:56:03Now they could spot ripe fruit.
0:56:04 > 0:56:07Colour vision helped give primates the advantage,
0:56:07 > 0:56:12kick-starting the evolutionary journey that resulted in us humans.
0:56:12 > 0:56:15That's why we have colour vision now
0:56:15 > 0:56:18and we have this wonderful rainbow of colours
0:56:18 > 0:56:21that we can see now and enjoy it.
0:56:25 > 0:56:30Fruit drove the evolution of so many of the traits of our ancient ancestors,
0:56:30 > 0:56:34but this simple need, the ability to see if fruit was ready to eat or not,
0:56:34 > 0:56:38had given primates perhaps for the first time on our planet
0:56:38 > 0:56:43this capacity to see in full glorious technicolour.
0:56:43 > 0:56:46And it's something that I think we just take for granted.
0:56:54 > 0:56:58Since they'd evolved 140 million years ago,
0:56:58 > 0:57:01flowers had transformed our planet.
0:57:01 > 0:57:04They'd come to dominate the plant kingdom,
0:57:04 > 0:57:06sculpting the Earth itself.
0:57:07 > 0:57:12Above all, flowers drove the evolution of animals,
0:57:12 > 0:57:14especially primates,
0:57:14 > 0:57:17shaping our human evolution.
0:57:29 > 0:57:32It seems to me that we are rather animal-centric.
0:57:32 > 0:57:36That by being members of the animal kingdom ourselves,
0:57:36 > 0:57:38we somehow see them as the thing that's at the heart
0:57:38 > 0:57:41of driving changes to life on Earth,
0:57:41 > 0:57:43but I don't think that's true.
0:57:43 > 0:57:46Most of the big changes to life on the planet
0:57:46 > 0:57:48have been brought around by flowers.
0:57:48 > 0:57:52They are the ones that are more manipulative, more inventive,
0:57:52 > 0:57:55more powerful than any of the animals that they are interacting with.
0:57:55 > 0:58:00Most animals are only here because of flowers, including us.
0:58:00 > 0:58:05It's an intriguing thought for next time you're out doing the roses.
0:58:06 > 0:58:10Next, we reveal the epic battle between the forests
0:58:10 > 0:58:13and their greatest challenger, a new type of plant...
0:58:13 > 0:58:15the grasses.
0:58:15 > 0:58:19It was a conflict that would set the world on fire.
0:58:19 > 0:58:23The victor would force our ancient ape ancestors out of the forests
0:58:23 > 0:58:25and into the savanna.
0:58:26 > 0:58:31And go on to trigger the birth of human civilisation.
0:58:37 > 0:58:40Subtitles by Red Bee Media Ltd
0:58:40 > 0:58:43Email subtitling@bbc.co.uk