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00:00Imagine a land so hostile that you'd need special equipment just to breathe.
00:30Where there's no shade and where the solar radiation would kill you in minutes.
00:38At night, temperatures plummet to sub-zero. You could freeze or fry in the same day.
00:50I'm not talking about a far away planet. I'm talking about Earth.
00:54500 million years ago, this was what the land was like to all life forms, alien and uninhabitable.
01:07Back then, life was only to be found in the sea.
01:10So how did it conquer this hostile world, taking an evolutionary journey that would one day lead to us?
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01:32Over the millennia, this harsh new world was invaded by a few pioneering lifeforms.
01:51These evolved into a multitude of animal designs, able to cope with the extremes of life on land.
02:02Our family, the mammals, is just one of the results.
02:18Every living thing is linked by the branches on the tree of life.
02:29I'm going to find out just how this extraordinary variety of animals arose, and how we are connected
02:41to each and every one of them.
02:48It's a story full of surprises, which leads from a fish to you and me.
03:00And if it hadn't been for one giant twist of fate, the dinosaurs might still rule supreme
03:08today.
03:13In the beginning, dry land was a no-go area for life.
03:21As well as deadly temperature extremes, there was the crushing effect of gravity.
03:27Setting foot on this new world would be an enormous challenge.
03:30It would be like trying to live on another planet.
03:39That's because all life started in the sea, where the temperature hardly changes and the water
03:44protects against the pull of gravity and the burning power of the sun.
03:51The sea was the first laboratory of life, and for more than three-quarters of life's history,
03:56it was home to every living thing.
04:02This was mostly a gentle era of soft-bodied creatures like jellyfish.
04:11Fish are 95% water and have no skeleton at all.
04:17Unlike us, they don't need one, because being underwater is like being in space.
04:35Water buoys you up, suspending all life in a three-dimensional world.
04:39It enables these kelp fronds to tower 30 metres upwards from the ocean bed.
05:04In fact, just like animals, for hundreds of millions of years, plants could only have
05:08only exist in the sea.
05:21On land, this watery support would all be gone.
05:25So what would happen then?
05:27Everything would collapse.
05:28Oh!
05:29Thrown back onto land.
05:30I'm suddenly aware of just how heavy all this kit is, and my own body weight.
05:44It's hard work, just even trying to get up.
05:48Gravity is definitely dragging me down.
05:53And for a jellyfish, the force of gravity is fatal.
05:57Once they collapse, they die.
06:06So how could any animal designed for life in the sea ever get out of the water?
06:11There was one group of animals in the sea that had just the right kit to get up and go onto
06:17the land.
06:25The arthropods had hard jointed skeletons.
06:30This living suit of armour holds their body up, so gravity can't pull it down.
06:50However gave the arthropods the staying power they needed to make it on land.
07:18Armour has made the crabs expert land grabbers.
07:35Some have now evolved to live far from the sea.
07:43These blue land crabs in Florida are found up to three miles from the beach.
07:51Crabs are actually well adapted to life on land.
07:54Their jointed outer skeletons may have evolved in the sea, but it also supports their weight
07:58on land, making it easy for them to get around.
08:02And it stops them from drying out.
08:14On the other side of the world, in the Indian Ocean, there's a land where the crabs have
08:18really made themselves at home.
08:24Christmas Island is completely overrun with red land crabs.
08:29A hundred and twenty million live on this small island, outnumbering the human residents by 300,000 to
08:38one.
08:42Once a year, vast numbers hit the road.
08:54They're heading for the beach.
09:04A hundred and twenty million live on this small island.
09:05A hundred and twenty million live on this small island.
09:08Because despite their armour, they can't shake off their ties to the sea.
09:25As a vital purpose to this mass manoeuvre, the females clasp thousands of soft eggs underneath
09:32them.
09:42Like all land crabs, they have to return to the water to release their eggs.
09:47Their young must grow up in the sea.
10:08But the first creatures ever to venture on land lived long before crabs even came into
10:13existence when the land was barren and lifeless.
10:17How do we know?
10:19Well, because like me, they're left footprints.
10:37Preserved in the rock in what is now Ontario, Canada, are the oldest footprints anywhere on
10:42earth.
10:49Just a few small steps for a bug, but one giant leap for life.
10:56These prints are 500 million years old.
10:59Their maker is thought to have been another armoured arthropod that looked like a giant
11:04woodlouse more than a foot long.
11:11But what made this ancient trailblazer drag itself ashore onto the barren land?
11:19Well, 500 million years ago, there were so many tooled up and hungry predators that the
11:24ocean had become a dangerous place to be.
11:28For the first time in the history of life, there was good reason to leave the crowded seas.
11:41And another ancient creature still retraces those first pioneering steps each year.
11:58The horseshoe crab has been around for hundreds of millions of years.
12:05And once a year, it still makes a dramatic pilgrimage to the beaches of North America.
12:11To breed.
12:12Horseshoe crabs lay their eggs on land to put them out of reach of marine predators.
12:28And it's likely that those early trailblazers first took to the beaches for the same reason.
12:40Job done.
12:41The horseshoe crabs turn around and crawl straight back into the sea.
12:47So those first trackmakers were probably just visitors too.
12:54But about 430 million years ago, another group of arthropods abandoned the sea for good.
13:04The colonisation of the land had truly begun.
13:07And it was creatures like millipedes that led the way.
13:12Others soon followed.
13:14Almost 100 million years before our ancestors left the sea.
13:19Today, more than 90% of all land dwellers are armoured arthropods.
13:25Including spiders, millipedes and insects.
13:28Making them the most successful group of animals on earth.
13:33The vast majority are insects, like ants, that have cracked the problems of breeding on dry land.
13:45Ants keep their eggs and young moist in nests underground.
13:49Where they're constantly cleaned by the adults.
13:54Driver ants now have sophisticated strategies to breed and feed on land.
13:59By massing in their millions around the nest.
14:02They raise its temperature and speed up the development of the young inside.
14:06Their sturdy skeletons carry them easily across the ground.
14:11And stop them drying out.
14:13These fearsome jaws have made them deadly hunters.
14:29Thousands work together as one giant predator.
14:32Devouring everything in its way.
14:34Many jaws make light work of animals far bigger than themselves.
14:41But the arthropod's jointed construction does have its drawbacks.
14:50Land crabs are amongst the most impressive land-based arthropods around today.
15:00And thankfully for me, they don't get much bigger than this.
15:03Because this one's already a handful.
15:05Because the bigger they get, the heavier their armour and the harder it is for them to breathe.
15:10So funnily enough, the adaptations that allowed them to leave the water in the first place,
15:15have now limited their size on land.
15:19Off you go.
15:21But there was another group of animals, built to a very different design.
15:34One that allowed them to get much, much bigger.
15:42It all started around 550 million years ago, with a tiny worm-like creature that lived at the bottom of the sea.
15:50This is its closest living relative.
15:53It's the Lancelot.
15:57It doesn't look like much, does it?
15:59So why is it so special?
16:02Well, the Lancelot has a revolutionary feature that was vital to our evolution.
16:08It's the notochord.
16:10A stiff rod running through the body.
16:12The beginnings of a backbone.
16:15A strong yet flexible lever for muscles to pull against.
16:19Having your skeleton inside also allows you to grow much, much bigger.
16:32Incredibly, the backbone evolved just once.
16:35But this one lucky break was a crucial turning point in the journey of life.
16:41It led to a completely new family of animals.
17:00The vertebrates.
17:02That's fish, amphibians, reptiles, birds and mammals.
17:14And that includes you and me.
17:17So the backbone, which evolved to help animals swim, would eventually help them to colonise the land.
17:26But to walk, you need legs.
17:29How did they evolve?
17:34Underwater, mudskippers look much like other fish.
17:37But watch what they can do with their fins.
17:50A fish that walks.
17:53Well, almost.
17:54The mudskipper can shuffle overland using two pairs of modified fins.
18:08This is how we once thought backbone creatures left the water.
18:15Ancient fish propped themselves up onto fins.
18:19And once ashore, the fins turned into legs.
18:22We now know that something rather more surprising happened.
18:31Legs actually evolved for use in the water.
18:35But how?
18:39The oceans are home to other bizarre creatures that appear to walk across the seabed.
18:46Rosy-lipped batfish never leave the sea.
18:50And they're perfectly good swimmers.
18:53But they also use their fins like pairs of legs.
19:02By stalking prey on stilt-like feet, they don't stir up the water or sand.
19:16So this shrimp doesn't have a clue.
19:35The frogfish has also evolved two pairs of modified fin feet.
19:40To help it navigate the nooks and crannies of the ocean floor.
19:43So fishy fin feet weren't a new idea.
19:55But evolution didn't really run with it until around 370 million years ago.
20:01When the climate changed.
20:06The earth warmed up and became covered in shallow, weedy swamps.
20:10Where normal fins got in the way.
20:14Over time, the paired fins started to evolve a better shape for pushing through the weeds.
20:23Until they ended up more like 4 feet.
20:25And those early four-footed creatures left a legacy which can be traced throughout the tree of life.
20:36Right up to the present day.
20:37They were the ancestors of all land-living, backboned animals.
20:49The four-legged blueprint had been set.
21:02And all vertebrates that have ever lived on land have followed the same basic pattern.
21:06And if for some reason our ancestral fish hadn't had two sets of fins, I might have ended up with two legs and no arms.
21:16Or even an extra set of arms.
21:17Which might have been quite useful round about now.
21:26Whoa, whoa.
21:28And not only that, we now know that we could have ended up with more fingers and toes as well.
21:33Having five might be just a fluke of nature.
21:35Fossils show that some of those early four-legged creatures that crawled through the swamps had six, seven or even eight fingers.
21:51But the one successful species that became the ancestor of all the later vertebrates just happened to have five fingers and toes.
22:10So having five fingers and four limbs is an ancient blueprint all land-living animals inherited.
22:17But what about animals such as horses, you might ask?
22:23Surely they don't have five fingers?
22:26Well, they don't have today.
22:29But their ancestors used to.
22:31They started off with five fingers like me.
22:34And then gradually over millions of years, they lost the use of four of them.
22:38Leaving them with this central digit here.
22:40Now the nail turned into the horse's hoof.
22:42And these three bones that are present in the finger are still present in the horse's leg today.
22:48And this big long bone is the same bone that's hidden within my hand.
22:52And surprisingly, my wrist is exactly the same joint as the horse's knee.
22:58OK, big fella.
22:59And some of those lost digits are still present at the start of every horse's life.
23:12For the first months inside the womb, a fold still has two extra toes.
23:18But in a replay of its evolutionary past, they fold back into the central cannon bone before it's born.
23:24We now know how our underwater ancestors evolved to walk.
23:43But there were other challenges they had to face in leaving the water for the hostile land.
23:48To start with, how would they manage to breathe?
24:01I can only breathe down here because of this, an aqualung.
24:06In the same way that I'd drown down here without this diving gear,
24:11life on land for fish is equally suffocating.
24:14Remarkably, though, there are some fish that can breathe air just like us,
24:22as they have done for 400 million years.
24:29Lungfish, still found in Africa and Australia today.
24:33For those first sea creatures that came ashore, it took the winning formula of lungs,
24:54and legs to make the quantum leap from ocean to land.
25:03Enter the first four-legged air breathers, our ancestors.
25:08But even these ground-breaking creatures couldn't conquer dry land just yet.
25:23First, the land itself would have to change.
25:26The drying and burning effects of the sun are potentially lethal,
25:41especially when you're exposed like this, with no shade.
25:57I have to drink about two litres of water a day just to compensate.
26:01And I've got a relatively waterproof skin.
26:06For the first four-legged creatures with their delicate skins,
26:12this was an even bigger problem than it is for us.
26:15They needed moisture and they needed shade.
26:17They had to wait for another invasion of the land.
26:22That of woody plants.
26:31Early plants were tiny algae, and like every other form of life, confined to water.
26:37Just like animals, to make it on the land, they had to combat gravity.
26:42They evolved a skeleton made up of rings of lignin.
26:45The plant's equivalent of bone.
26:51Now they could leave water and stand alone.
26:56Lignin gave the plant cells strength to keep on growing up and up.
27:05Reaching towards the sunlight.
27:15Lignin eventually expanded to fill up the cell walls and form wood.
27:32And wood allowed plants to really make it big.
27:36They evolved into the incredible hoax of the land.
27:44The trees.
27:45Eventually, the battle for light led to lush forests.
27:55Cool, shady and moist.
27:57Ideal conditions for delicate creatures like our ancestors.
27:58So lignin created wood.
27:59And wood created forests.
28:00Without which, we wouldn't exist.
28:01Without which, we wouldn't exist.
28:02So lignin created wood.
28:03And wood created forests.
28:04Without which, we wouldn't exist.
28:05Lignin created wood.
28:06So lignin created wood.
28:07And wood created forests.
28:08Without which, we wouldn't exist.
28:13And those 어�инons created oluşly transformate.
28:21These trees in the middle of nature.
28:22And these trees would let us love the stuff,
28:24we had such a big surprise.
28:28That is the sperr if we could live in here.
28:36Is all the seeds from the nature of one place.
28:40And those early four-legged animals had a whole new world to explore, with all the moisture
28:47and shade they needed.
29:00Damp forests everywhere are still inhabited by their descendants, the soft-skinned amphibians.
29:10There are now more than 4,000 species, but even today, some 350 million years later, amphibians
29:19can't escape the pull of their aquatic roots.
29:29Every spring, just after the snow melts, there's an extraordinary mass migration through the
29:34forests of North East America.
29:36Thousands of spotted salamanders that have spent the past year hidden underground emerge
29:47with one mission in mind.
29:51To get to water for a single night of passion.
29:58Then, the females spawn.
30:20Amphibian eggs are soft and dry out quickly in the air, which is why spotted salamanders
30:37must still return to the water to breed.
30:45But ever since their ancestors first crawled out of the swamps, amphibians have come up
30:50with all kinds of weird and wonderful ways to break free from the water.
31:09The mountains of northern Spain, a rocky, barren landscape.
31:19But the midwife toad is perfectly at home.
31:22It has evolved to live and breed on dry land.
31:28So what do midwife toads do that salamanders don't?
31:38A pair meet up and start to mate.
31:45The male's embrace squeezes the female until she releases her eggs.
31:57She catches them in her back legs, where he fertilises them.
32:05But there's no water here.
32:07How will the eggs survive?
32:11The male midwife toad is one of nature's new men.
32:14He hoists the eggs up his legs, as if putting on a pair of shorts with no hands.
32:29From now on, the eggs are his responsibility.
32:32He carries them away and burrows under a rock to keep them moist.
32:40The male holds up for several weeks.
32:46Then he has to go off to search for a pond.
32:54He must return to water, where the tadpoles wriggle free and grow up, just like other toads.
33:00In this forest in Costa Rica, I can hear frogs calling to their mates all around me.
33:24But there are no pools or streams that I can see.
33:29How do they manage to breed here?
33:35This is the strawberry poison arrow frog.
33:38And on its back is a tadpole.
33:41It hatched on the ground, but now it gets a piggyback from mum, as she begins a mother
33:46of a climb.
33:50She carries her tadpole all the way up into the trees, to its own cradle in the canopy.
34:13In these hanging gardens, up to 20 feet above the forest floor, an egg-cup-sized pond is
34:19all this mother needs.
34:34And after all this effort, her work still isn't finished.
34:38A few days later, she has to make the same climb all over again.
34:46Because although her tadpole has water in its tree-top nursery, it has no food.
34:52So it waits for her, like a chick in its nest.
35:00As she lowers herself in, it headbutts her, even gives her a little nip.
35:07Until she gives it what it wants.
35:11She lays an infertile egg for it to eat.
35:18With regular meals from mum, the tadpole has all it needs in its tiny world to grow into
35:23a frog.
35:32Strawberry poison arrow frogs may be the hardest-working frog mothers on earth, but another frog takes
35:37the award for the most devoted frog father.
35:48Guess where the Darwin's frog keeps his tadpoles?
35:58The male's throat is the nursery where the tadpoles grow.
36:06He gives birth by spitting out the froglets fully formed.
36:16So the Darwin's frog has reduced its need for water by carrying its own pond around inside
36:22it.
36:24But despite all these extraordinary solutions, almost all amphibians are still basically tied
36:30to water, just as their early ancestors were.
36:35So how did the first land-living animals colonise the deserts and dry lands?
36:41The entire spawning process had to be transformed.
36:50These evolved their own internal life support system, and at the same time shells developed
36:56that could hold water.
37:03The arrival of the hard-shelled egg was one giant step forward on the journey of life.
37:13Each egg provided the growing youngster with its own portable pond.
37:17Eggs could now be laid on dry land, and this led to a whole new group of animals.
37:24The reptiles.
37:36The reptile eggs contain more food reserves than those of amphibians, giving their babies
37:41a head start in life.
37:59Australian bearded dragons hatch out fully formed and ready to take on the world, just
38:04as they've done for millions of years.
38:20The reptiles evolved into many families, including one of the most impressive dynasties ever to
38:26dominate the land.
38:36The smash hit that was the hard-shelled egg led to the age of the dinosaurs.
39:06The dinosaurs ruled the earth for about 180 million years.
39:16There were as many as 700 species, from the size of a rat to that of a whale.
39:26But the egg wasn't the reptile's only strength.
39:29They had another trick up their sleeve.
39:32Their skin.
39:34A tough, scaly armour that could withstand the driest conditions on earth.
39:42And you don't get much drier than the sand dunes of Namibia.
39:53But even here, reptiles have solved the problem of drying out.
40:00And they can turn the power of the sun to their advantage.
40:07Last thing in the morning, the cold-blooded chameleon heats up its side by facing it to the sun.
40:24Once it's recharged its solar batteries, it's ready to go hunting.
40:36Here, armoured arthropods have met their match.
40:39Despite arriving more than 100 million years later, reptiles now appear to have the upper claw.
40:58But even reptiles have their limitations, because they slow down as the temperature drops.
41:10And when the sun is gone, it can get very cold.
41:17But for us and other mammals, temperature does not limit where we can live.
41:22We can be active whether it's hot or cold.
41:26We do it by heating ourselves from the inside.
41:30And we do that by burning up food.
41:36The reason my face is white-hot and hers is a cool red is because I'm generating heat inside.
41:48Whereas she is cooling down as she loses the heat that she's absorbed from the sun during the day.
41:55But it's no good having an internal heating system if all that heat is simply lost.
42:05Which is what's happening to me right now.
42:07You'd have to eat non-stop just to stay alive.
42:19What you need is good insulation.
42:25So there would have to be another breakthrough before land animals could reach the coldest corners of the world.
42:46About 200 million years ago, a reptile-like ancestor of mammals started growing fine barbs underneath its skin.
42:54Over many generations they became finer and longer until eventually they turned into hair and fur.
43:03The mammals had arrived and now they were ready to take on the elements anywhere.
43:17Musk oxen have the ultimate fur coats.
43:22Their insulation is so good they can survive at temperatures of minus 40 degrees Celsius.
43:32Warmed by their central heating and stoked up by regular meals,
43:36most oxen have managed to beat the elements and eat their way north to the fringes of the Arctic Ocean.
43:43We haven't been in England because these are currently in the Middle East.
43:46We have a natural and
44:12to the icy reaches of the poles.
44:27And this must be the ultimate test.
44:36Dense fur allows the baby seal to undergo the biggest temperature shock experienced
44:41by any animal on earth.
44:45That's from around 40 degrees inside its mother's body to as low as minus 30 when it's born
44:52and it hits the ice.
44:55The miracle of this baby's survival here depends not just on fur but on its mother's dedication.
45:02She provides the fuel that keeps it warm inside.
45:07But the mammal that really takes parenting to the extreme is the elephant.
45:31It takes nearly 22 months to make a baby elephant, longer than any other animal.
45:50During that time, the embryo floats in its own centrally heated world, an echo of life's
46:06earliest existence in warm primeval seas.
46:09And it's safer than inside an egg, mum has total control over the baby's growth.
46:20After investing all that effort even before birth, it's not surprising mammals take exceptional
46:25care of their young.
46:41For a mammal mother, birth is just the start of a long and demanding job.
46:45A mammal mother is a mobile milk bar, and delivering enough of the white stuff to build up baby is
47:05an even greater drain on her than pregnancy.
47:10Milk is highly nutritious, and at this stage it's the only food the baby needs.
47:17As long as no one tries to nick it.
47:26Like all mammals, baby elephants learn through play, and it's a good excuse to mess around.
47:33For a while, the birds are the same, or the birds of the sea.
47:45The birds of the sea are a great source of the wild, and the birds of the sea are a great
48:01It's been an extraordinary journey.
48:05We've evolved a backbone, lungs and four limbs.
48:13With five fingers and toes.
48:19We've grown fur and developed central heating
48:22to cope with extremes of temperature on land.
48:26But the mammals needed other changes to a body design
48:29which originally evolved in the sea.
48:33Our eyes work fine underwater.
48:36We can even taste there.
48:38But hearing is a different matter.
48:45Sound travels very differently
48:47because water is 800 times as dense as air.
48:52So animals living on land
48:54had to develop a totally new way of hearing.
48:59And when it comes to ears,
49:14few mammals are more advanced than the bat-eared fox.
49:17It lives in the South African bush, where it scans the ground, listening for a meal.
49:32It hears in the same way as all mammals do.
49:35It's just more sensitive.
49:36Broad outer ears capture the sound waves in the air
49:43and funnel them through to the eardrum, making it vibrate.
49:49Tiny bones in the middle ear transmit and amplify these vibrations.
49:53The sound waves are then converted into nerve impulses and sent to the brain.
50:11Bat-eared foxes can hear grubs and termites moving nearly a foot below the ground.
50:16Bad news for arthropods.
50:17A mammal's ear is a high-tech triumph.
50:31So how did the chance workings of evolution create such a remarkable device?
50:35Well, believe it or not, it all began in the solid jaws of prehistoric reptilian animals.
50:43Over millions of years, two of the jaw bones became detached, shrank and moved upwards to become the key components of the mammal ear.
50:52They were hijacked by evolution for an entirely different use.
50:56It's amazing to think that these delicate ear bones have evolved from bones that were originally designed so our reptile-like ancestors could bite their prey.
51:08If you don't believe me, try eating an apple.
51:13We can sense echoes of our evolutionary past every time we chew.
51:18We hear every crunch through our jaw bone.
51:21It's not only mammal senses that have been perfected through evolution.
51:27Mammals, and I include myself here, have also become the cleverest animals on Earth.
51:37And there aren't many more intelligent than baboons.
51:41They lead a complex social life.
51:44It's not just who you know, but what you do with that knowledge that counts.
51:47Male baboons use brains, as well as brawn, to get their way.
52:05If one male is threatened by another, he'll pick up a baby as a living shield.
52:09He knows that no baboon will risk hurting the youngster by attacking him.
52:15As well as being devious, baboons use their intelligence to find new things to eat.
52:32Some have learnt the art of ambush, to get much larger meals.
52:49All right.
52:52Pardon theте fromんだ.
52:54What do you eat?
52:56Do not Oooh, what do you eat?
52:59Not to do sometimes times to spend a pound of slave cuman being a heavy dog's.
53:01What do you eat?
53:16Don't do some strength in the city either.
53:19Mammals are now one of the most successful of all groups of animals.
53:47They can cope with the most extreme climates on the planet, from the scorching heat of
53:52barren deserts to the steaming rainforests, and from the deepest seas to great cities.
54:01It could have been very different.
54:18More than a hundred million years after our mammal ancestors had arrived, the land was
54:23still ruled by dinosaurs.
54:28Most of the early mammals were shrew-like creatures that ventured out mainly at night.
54:34The dramas of their lives took place entirely in the shadow of the giants.
54:51The
54:51the
54:52the
54:54the
54:58the
55:00the
55:04But one event 65 million years ago played right into the mammal's hands.
55:34A massive meteorite collided with the Earth, and 85% of all land-dwelling animals were snuffed
55:57out. The dinosaurs became extinct over just a few thousand years. But among the animals
56:07that did survive were mammals. Perhaps that was because they fed on the other major group
56:18of survivors, the armoured arthropods. With the dinosaurs gone, the mammals seized their
56:26chance, diversifying and expanding to fill the world.
56:34The mammal line exploded into the wonderful variety we see today.
56:53Ultimately, that led to us. If that meteorite had missed the Earth, we probably wouldn't
57:02be here. We've come a long way since our ancestors first crawled out of the sea. We've coped with
57:10everything that this hostile new world can throw at us.
57:17Can we call ourselves the true inheritors of the Earth?
57:24No. It's the armoured arthropods. They colonised the land 100 million years before we vertebrates.
57:36And today, they outnumber all other animals combined. Many have hardly changed in over 200 million years.
57:48On their journey of life, the land-grabbing arthropods developed an almost bomb-proof design.
57:57And no doubt they'll still be here, long after we've gone.
58:16Next week on The Journey of Life, I'll find out how life grew wings and conquered the skies.
58:22The Journey of Life
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