Wonders of Life (2013) s01e03 Episode Script

1 In 2009, a new species of spider was identified.
A spider with superpowers.
It was named exactly 150 years after the publication of Darwin's On The Origin Of Species, in which he explained why life on Earth is so diverse and so complex.
Darwin's theory of evolution by natural selection was built on the work of naturalists who were discovering thousands of new species across the world.
That process of finding species new to science and naming them continues to this day.
And it's recognised in the name of this newly discovered arachnid.
Darwin's bark spider.
The spider occupies a unique niche.
It can hunt where no other spider can.
That spider creates the largest webs found anywhere on Earth.
In order to do that, it has to produce the strongest silk of any spider.
They can span over 25 metres across lakes and rivers.
And actually, no-one knows how they get their webs across such a large distance.
But Darwin's bark spider is one of thousands of unique species of animals and plants that you find in Madagascar.
The rainforests here are one of the most bio-diverse places on the planet.
And each year, more discoveries are made as researchers try to understand why this tiny corner of the universe is so prolific.
All of these living things were found within a five-minute walk of this field station.
And the diversity is remarkable.
There's a chameleon there.
These are orchids.
This big green leaf is a traveller's palm.
There are four species of mushroom on that branch alone.
Across Madagascar, there are over 14,000 species of plants, there are hundreds of species of mammals, birds and reptiles and over 90% of them are unique to this island.
How could it be that so many diverse living things, so beautifully adapted to their environment, could've emerged from a universe that's governed by a simple set of natural laws? The fact that we know the answer to that question is one of the greatest achievements in science.
In this film, I want to explore how these endless forms, most beautiful, have emerged from a lifeless cosmos.
Africa.
A whole continent full of creatures utterly different from those in Madagascar.
But the diversity of life doesn't stop at what you see.
Because within each individual lies another world of complexity.
This, believe it or not, is the top predator in Africa.
Or she will be when she's older.
She's only about eight weeks old now.
Her body is built from a host of different molecules and by far the most diverse group are known as proteins.
We can see the proteins here.
Those claws, so vital for a lion's survival, are made of a protein called keratin.
Her eyes, also absolutely vital for her survival, have a protein called opsin which is bound to a pigment to make structures called rhodopsins which allow her to see in colour and also to allow her to see very well at night when she's hunting.
There are also proteins in her muscles myosin and actin, which are the things that allow her to run away.
The proteins in a lion come in countless different forms.
But they all share something in common.
A backbone of carbon.
An atom that's able to form long, complex molecules.
Of all the 92 elements, there really is only one that has that appetite for bonding its four electrons - to share them with other molecules.
Carbon will share those electrons with nitrogen, oxygen, hydrogen, and critically, with other carbons, to build up these immensely complex chains, the amino acids and the proteins which are the building blocks of life.
So to understand our planet's endless diversity, we must begin by considering this life-giving element.
I've got a few scratches now because of you! Because of your proteins! After all, to build a lion, you must first build carbon.
And that's a story that stretches back to a time long before there were even stars in the universe.
13.
5 billion years ago, just a few hundred million years after the Big Bang, the universe was a carbon-free zone.
An infinite, sterile gloom of hydrogen and helium clouds.
Until, one day, those vast clouds began to collapse under the force of gravity.
Long before the solar system, Earth or life existed the first stars were born.
The birth of the first stars did much more than illuminate the universe, because that set in train a sequence of events which is necessary for the existence of life in the universe.
And we can still see that process playing out in the universe today.
This is the brand-new South African Large Telescope.
Number three amps, gear right, gear box.
Its mirror is 11 metres wide, making it the largest optical telescope in the southern hemisphere.
And it recently helped to pin down what's happening in an object some 650 million light years from Earth.
This beautiful, almost lifelike system is known simply as the Bird.
It's the spectacular result of what we used to think was two galaxies colliding.
It's events happening in the head of the Bird that are most interesting from a perspective of life in the universe.
Because the head is formed by another galaxy, a third galaxy, an island of billions and billions of stars, colliding with two galaxies that form the wings and the body at a speed of around 250 miles a second.
The turbulence, the disturbance, that that creates is causing many new stars to be formed.
These stars begin their lives by burning hydrogen, to produce ever more helium.
But as they age, as the hydrogen runs out, they turn to this helium.
The temperature at their core rises increasing the chances of three helium nuclei fusing together to form a new element - carbon.
That process has been going on for almost the entire history of the universe, back 13 billion years, and it's the formation of stars that is the vital first step in the formation of life, because stars produce the heavy elements in the universe including carbon.
From the universe's earliest times, carbon has been created inside ageing stars.
And over time, this carbon has built up, drifting through the cosmos as dust until some of it was caught up in the formation of a planet called Earth.
And it's here that we can see this ancient carbon brought vividly to life.
Today, the universe is old enough that countless stars have lived and died.
So, there's been plenty of time to synthesise the primordial hydrogen and helium into the heavy elements.
The question now is, how does that carbon get into the web of life? Well, today, it enters via one ingredient and I'm going to measure it using this balloon.
The ingredient is carbon dioxide, which plays a key role in photosynthesis.
Each night the carbon dioxide concentration increases, filling the air around the leaves at the top of the trees.
This balloon has a carbon dioxide monitor in it which is going to measure the change in the levels of CO2 at the top of the forest canopy as night turns to day.
As the sun rises, the trees begin to photosynthesise.
At 6pm last night, just after sunset, the concentration was around 350 parts per million.
Around 10pm, around four hours after sunset, the concentration had risen to about 400 parts per million.
Now, at about midday, the concentration's back down to about 345 parts per million.
So that's a variation over a period of about 18 hours of 10% in the concentration of carbon dioxide, just in that piece of atmosphere at the top of the forest canopy.
What you are seeing there is photosynthesis in action.
Every day, across the planet, photosynthesis uses sunlight to turn carbon dioxide and water into simple sugars.
The overwhelming majority of the carbon is locked up inside long chains of sugar molecules called cellulose and lignin.
Lignin is the stuff that gives wood its strength.
So, in this form, remember, that is most of it, it is very difficult indeed for animals to access.
For the energy and nutrients locked away in these long carbon chains to move through the food web, they must be broken down.
The best place to see that process in action is out on the open plain.
It's one vast larder for all manner of organisms.
By far the most effective harvester of carbon is actually one of the smallest creatures on the savanna.
Termites are social insects, working together to form a characteristic sight, seen all over the bush.
That's a termite mound.
Actually, it's the tip of the iceberg.
The termite city extends way beyond that underground.
And its function is fascinating.
It's essentially an air-conditioning system.
What it does is maintain specific conditions inside the mound - the conditions of the rainforest.
When the termites first colonised the savanna 30 million years ago, they brought the rainforest with them to support a form of life that was already wonderfully adapted to living off dead wood.
This is what these termite mounds are all about.
Can you see those structures, those white honeycomb-like structures? Those are called fungal combs.
They're wood pulp and possibly bits of dead grass that the termites bring in and build into that structure.
And the reason the conditions have to be the same as the rainforest is because they grow a particular genus of fungus called termitomyces around those honeycombs.
The job of that fungus is to break down the lignin and cellulose inside the wood and convert it into a form that the termites can eat, which you can see there, the little white nodules, just present on the honeycomb structure.
The termites lack the enzymes to break down the wood efficiently, so they have become farmers, tending to one giant social stomach.
There's a very intense relationship between the termites and the fungus.
You don't find that fungus anywhere else in the world as far as we know, other than inside termite mounds.
It's thought that up to 90% of the carbon locked up in lignin in this part of Africa is released back into the food chain again, solely by those termites and that fungus.
So the termites deal with most of the lignin, but that still leaves a vast store of carbon in the form of cellulose.
Across Africa, herds of mammals graze on grasses and leaves, turning the cellulose into meat.
Many are a type of mammal known as a ruminant the largest of which is one of the easiest animals to spot on safari.
There's a giraffe there as well.
Giraffes live off a diet similar to termites.
They eat cellulose.
Primarily the tops of the acacia trees that you see scattering the African savanna.
And they face that same problem, they've got to break those difficult carbon bonds down and they've come up with a very similar solution which is to cultivate bacteria and fungi.
But they do it inside their stomachs and ruminants like giraffes have had to build a very complex system in order to do that.
They've got four stomachs, one of them contains their culture of bacteria and fungi, and they allow them to digest that difficult cellulose.
Even with all this hardware, ruminants must feed for over two thirds of the day.
But there are other creatures here that have found a short cut, after all, if plant fibres are hard to digest, why not let someone else do the work and simply steal a meal? It's coming for us.
Oh, my God Look what we've just found.
We were out looking for giraffe this morning, and we found about ten of them over there, but in looking for the giraffe, we've just found a leopard.
This is one of the top predators out here.
He's got very little to fear apart from other leopards and maybe lions.
He's having a good look, he certainly doesn't care about us.
He's around two years old and at the moment, he doesn't have his own territory, he's too young for that.
So he's lying low.
He'll have to make about two kills a week, to stay in good condition.
So, maybe he'll catch an impala every three to four days, and he's obviously doing that.
Because, look at him! He's looking for protein.
He likes your boom.
And I'm a little bit worried, cos I'm protein! Oh, wow.
He's after your boom, George.
He's coming really close to us because he's after the sound man's boom pole.
Which is oh! That's incredible.
I just He's taken it From its origin in the death of stars its capture by plants through insects, mammals and on.
The carbon cycle is the real circle of life.
Out there tonight, the relentless recycling of carbon through the food chain will continue.
As night falls, you can almost sense it - the change in the sounds and the atmosphere.
Some will die, so that others can live, as carbon leaps from branch to branch across the great tree of life.
And guiding it along its way is just one very special form of chemistry.
Every living thing is just a temporary home for carbon atoms that existed long before there was life on Earth and will exist long after Africa and Earth are gone.
But, the pattern of life, the information needed to build a zebra, or a tree, or a human being or a lion persists.
It's passed on from generation to generation, in a molecule.
A helical molecule with a backbone of carbon called DNA.
"Atmosphere" by Joy Division There was a time when Earth appeared empty.
Walk In silence Don't walk away In silence Yet despite appearances, 3.
8 billion years ago life was already under way, in the form of tiny living specks that probably all shared the same biochemistry.
We know that every living thing on the planet today - so every piece of food you eat, every animal you've seen, everyone you've ever known or will know, in fact every living thing that WILL ever exist on this planet - was descended from that one speck.
Walk In silence We call it the last universal common ancestor, or LUCA.
So, just as the universe had its origin at the Big Bang, all life on this planet had its origin in that one moment.
Less than a billion years after its formation, there was already life on Earth.
It's possible that some of it used biochemistry utterly different from the life we see today.
If so, it has long been extinct.
It's also possible that the first life may not have been cellular - just living chemistry in the porous rocks of some ancient ocean.
We're not sure, but what's certain is that one day, a population of organisms showed up with biochemistry that we WOULD recognise.
This was LUCA.
The first expression of a form of life that would in time throw up a group of humans who left their mark in this part of Africa.
Now, we don't know what LUCA looked like, we don't know precisely where it lived or how it lived.
But we do know this.
If you start to trace my ancestral line back to my parents, to their parents, to their parents, to their parents, all the way back through geological timescales over hundreds of thousands of millions and billions of years, there will be an unbroken line from me all the way back to LUCA.
We know that, because every living thing on the planet today shares the same biochemistry.
We all have DNA.
It's made of the same bases, A, C, T and G.
They code for the same amino acids.
Those amino acids build the same proteins, which do very similar jobs, whether you're a plant, a bacterium, or a bipedal hominid, like me.
So all life uses the same fundamental biology those four bases, A, C, T and G, which code for just 20 amino acids, which in turn build each and every one of life's proteins.
Be you bacteria, plant, bug or beast, your design comes from your DNA.
So it's this molecule that must hold the key to understanding why life today is so diverse.
We now know that the answer to the question, "Why is life on Earth so varied?" is actually the answer to the question, "Why is the DNA molecule itself so varied?" What are the natural processes that cause the structure of DNA to change? Well, part of the answer actually doesn't lie on Earth at all.
It lies up there amongst the stars.
And I can show you what I mean, using this, which is a cloud chamber, a piece of apparatus that has a unique place in the history of physics.
I'm going to cool it down using dry ice, frozen carbon dioxide, just below -70 degrees Celsius.
I'll put the top on.
Hear that? That's the metal at the bottom of the tank cooling down very rapidly to -70.
The cloud chamber works by having a super-saturated vapour of alcohol inside the chamber.
Plenty on there Now, I want to get that alcohol, I want to boil it off, to get the vapour into the chamber.
So I'm going to put a hot water bottle on top.
This is the first genuine particle physics detector.
It's the piece of apparatus that first saw antimatter.
And it really does consist only of a fish tank, some alcohol, a bit of paper, and a hot water bottle.
There, look at that.
Do you see that? Cloud vapour trail.
That's a cosmic ray.
That was initiated by a particle, probably a proton, that hit the Earth's atmosphere.
It almost certainly originated outside our solar system and was accelerated by the magnetic fields of our galaxy.
It may even have begun its life BEYOND our galaxy.
Now, imagine if one of those hits the DNA of a living thing.
What that will do is cause a mutation.
That mutation may be detrimental, or, very, very occasionally it might be beneficial.
And I think it's quite wonderful to imagine that maybe one of the key mutations that was selected for over the millennia that led to some trait in ME was caused by some particle that began its life perhaps in a massive supernova explosion, perhaps outside our galaxy and went and hit the DNA of something and caused some kind of beneficial mutation.
We don't know, but you can dream, can't you? Mutations are an inevitable part of living on a planet like Earth.
They're the first hint at how DNA and the genes that code for every living thing change from generation to generation.
Mutations are the spring from which innovation in the living world flows.
But cosmic rays are not the only way in which DNA can be altered.
There's natural background radiation from the rocks, there's the action of chemicals and free radicals.
There can be errors when the code is copied.
And then all those changes can be shuffled by sex, and indeed whole pieces of the code can be transferred from species to species.
So, bit by bit, in tiny steps from generation to generation, the code is constantly randomly changing.
Now, whilst there's no doubt that random mutation does alter DNA, evolution is anything but random.
It can't be, because the chances of something with DNA as complex as this appearing by luck alone are vanishingly small.
Imagine you just changed one position in the code at random, a random mutation.
There are four letters, A, T, C and G, so there are four possible combinations.
If there are two places in the code, there are four combinations for each one.
So that makes 16.
If there are three, then there are 64 possibilities.
By the time you get to a code with 150 letters in it, then there are more possible combinations in the code than there are atoms in the observable universe.
Now, a hippo has a code with around three billion different letters.
So the number of combinations of those letters, the chances of producing that code at random, are absolutely, infinitesimally small.
It's impossible.
So there must be a non-random element to evolution a natural process, which greatly restricts this universe of possibilities, and shapes the outcome.
We call it natural selection.
And to see it in action, let's return to where we began on the island of Madagascar.
Around 65 million years ago, a group of seafarers were nearing the end of a long journey across the Indian Ocean.
These were accidental travellers, a group of creatures from Africa, trapped on a natural raft and carried by the ocean currents.
The land they found was virgin green territory.
Plants, insects, reptiles and birds had established themselves, but there were none of their own kind.
They were caught up in a saga that tells of the great shifting of Earth's continental plates.
It's impossible to understand the diversity of life on Earth today without understanding the shifting geography of our planet.
Here's a map of Earth's southern hemisphere as it was 150 million years ago, and you see it's dominated by a single landmass called Gondwana.
And then, 90 million years ago, Gondwana had begun to break up, to separate, into something that looks quite recognisably like Africa, and these two islands, Madagascar and India.
Now, subsequently India has drifted northwards and bumped into Eurasia, raising the Himalayas.
But, crucially, Madagascar has remained isolated.
It's been an island surrounded by ocean for almost 90 million years.
So, when those seafarers arrived on their raft of trees and twigs and leaves, they had a blank canvas - two, three, maybe even a single pregnant individual had a whole island to roam across.
And over 65 million years, they have blossomed into hundreds and thousands of individuals, and become Madagascar's most iconic animals.
Finding the descendants of those ancient mariners is not easy.
But local guide Joseph has been tracking them for years.
And he's going to help me find them.
There at the top of the tree is an indri, which is the largest lemur in Madagascar.
He's just sat there watching us quietly at the moment.
This lemur here is a very special lemur.
He has a name, he's called David.
After Sir David Attenborough.
Now, we can only do this because Joseph has spent a lot of time with these lemurs.
So they trust him.
And therefore, it seems, they trust me.
Its enormous hands! The reason, it's thought, that we find lemurs here in Madagascar and Madagascar alone is because there are no simians, there are no chimpanzees, none of my ancestral family, dating back tens of millions of years, to out-compete them.
So what's thought to have happened is that around 65 million years ago one of the lemur's ancestors managed to sail across the Mozambique Channel, and landed here.
There were none of those competitors here, and so the lemurs have flourished ever since.
There are now over 90 species of lemur, or subspecies, in Madagascar, and no species of my lineage, the simians.
Over a vast sweep of time, the lemurs have diversified to fill all manner of different habitats.
From the arid, spiny forests of the south to the rocky canyons in the north, there is something about this island that is allowing the lemur's DNA to change in the most amazing ways.
We're on the hunt for an aye-aye, the most closely related of all the surviving lemurs to their common ancestor.
Oh, yes Oh, yeah.
Just shone the light up, and we saw these absolutely Two bright red eyes, shining out.
She's very high up at the moment.
Don't want to lose sight of her in this forest, which is very dark and dense.
The team have located a female aye-aye, and her son.
They want to attach radio collars to track their movements, and better understand how far they range through these forests.
But first, they must sedate them with a dart.
He's waiting for it to come down low enough to get that clean shot - I mean, how you get a clean shot in this I have no idea.
After two hours of traipsing through the treacherous forest, the aye-ayes remain at large.
Well, here is the aye-aye that was tranquillised last night.
They finally got her about half an hour after we left.
I think it was probably because we were disturbing her.
Apparently as soon as we'd gone, she came down the tree and she was tranquillised.
And as you can see she's pretty well sedated now, which is fortunate for me because she has certain adaptations that I wouldn't like to be deployed.
You can see there her teeth.
Her teeth are very unusual for a primate - in fact, unique, because they carry on growing, so she's much more like a rodent in that respect.
And that's so she can gnaw into wood.
You see, aye-ayes have filled a unique niche on Madagascar.
It's a niche that's filled by woodpeckers in many other areas of the world.
What she does is she feeds on grubs and bugs inside trees, and to do that, she has several unique adaptations of which her teeth are one.
The most startling is this central finger here.
It's bizarre.
It's got a ball and socket joint, for a start, so it has complete 360-degree movement.
It feels to me almost as if it's broken, but it isn't, it's just, you can move it around in any direction.
And she uses that finger initially to tap on the trunk of the tree, and then, listening to the echo from that tapping, with these huge ears she can detect where the grubs are.
And then, she gnaws through the wood with those rodent-like teeth, and then uses this finger again to reach inside the hole and get the bugs out.
So the question is, why? How could an animal be so precisely adapted to a particular lifestyle? She's waking up now! And the answer is natural selection.
See, what must have happened is way back, when the ancestors of the lemurs - the Lemuriformes - arrived in Madagascar, there must have been a mutation that lengthened the middle finger ever so slightly of one of those lemurs.
And that must have given it an advantage.
That must have allowed it perhaps to reach into little holes and search for grubs.
There's some reason why that lengthened middle finger meant that that gene was more likely to be passed to the next generation and then down to the next generation.
So that landscape of possibilities is narrowed, it's narrowed because that gene persists.
And it's persisted now for at least 40 million years, because this species has been on one branch of the tree of life now for over 40 million years.
And so, over those years that middle finger has got more and more specialised.
Natural selection has allowed the aye-aye's wonderfully mutated finger to spread through the population.
And this same law applies to all life.
If you have a mutation that helps you in the struggle to survive, you are more likely to leave more offspring.
And in the next generation, that mutation is more likely to survive.
So this animal is a beautiful example, probably one of the best in the world, of how the sieve of natural selection produces animals that are perfectly adapted to live in their environment.
Now, there are many reasons to study the aye-aye.
But here's a good one.
In the 1970s, it was thought the aye-aye was extinct.
Now, we know there are several thousand in the forests of Madagascar - 5,000, 6,000, 7,000, certainly less than 10,000 - but over the last 50 years, 50% of this forest has vanished.
This is an animal that's been around as a species for over 40 million years.
So it's important to know how these animals are doing, and how they're surviving in this diminishing habitat.
Whilst natural selection explains why the aye-aye evolved, it alone can't explain how a small group of individuals, over 60 million years ago, gave rise to over 90 different species of lemur today.
But there is another form of life that can offer us a clue.
Up here in the high forest canopy, we're in a very different environment to the one down there on the forest floor.
It's a more arid environment, it's almost like a desert.
It's exposed to the sun, water is harder to come by.
And so, this is a sea of different niches, that are able to be occupied and exploited by animals that are different to the ones you'll find down there on the floor.
So, in a very real sense, this is an island, an island to be colonised.
And sure enough, there are settlers to be found, even here.
You see that thing that looks like a muddy ball there, on the branch? Well, that's an ants' nest, it's home to a species of Crematogaster ants that are unique not only to Madagascar, but to the forest canopy.
You see, what makes those ants unique is that they can build their own nests.
There are very few species of ants that can do that.
So that is an island, that is a niche, and it's allowed that species of ant to develop because they're isolated from the rest of the ecosystem.
And astonishingly, within this niche, another form of life new to science has been discovered a beetle that manages to survive here unharmed by the ants.
How it does it is a mystery.
But what IS known is that this particular species has only ever been found inside these nests.
So, that really is its own mini-ecosystem, with species living in it that are unique to that island.
We live on an ever-shifting, dynamic world that creates islands in abundance.
Earth's mountain ranges, river valleys and canyons all create islands for life.
And it's these islands that those ancestors of the lemurs found when they arrived in Madagascar.
Empty niches, where populations became isolated, and over great swathes of time involved into such wonderfully diverse forms.
150 years on from the Origin Of Species, the subtlety and beauty of Darwin's insight is still revealing itself to us.
It describes how our beautiful, complex tree of life has grown from a once desolate universe.
The chemistry of carbon allows for the existence of a molecule that is able to replicate itself, and pass information on from generation to generation.
There can be random changes in the structure of that molecule - mutations - and they are tested by their interaction with the environment and with living things.
The ones that pass that test survive, and the ones that fail that test are lost.
The separation and isolation of living things onto islands - which may be physical, like Madagascar, or just the single branch of a single tree - results in speciation, the explosion of living forms highly specialised to occupy niches within niches.
And this is the explanation for the diversity of life on Earth.
"There is grandeur in this view of life," as Darwin wrote, and understanding how it happened surely only adds to the wonder.
As precise as Einstein's theories of relativity, and as profound as thermodynamics, Darwin has given us another universal law.
Evolution by natural selection.
And if evolution is the law on this island, then it will apply throughout the cosmos.
Which begs a big question.
Could there be other "trees of life most beautiful" amongst the stars? In 2011, we discovered a rocky planet orbiting around a distant star, with daytime temperatures not too dissimilar to those found on Earth.
Now, there must be millions if not billions of such planets out there in the universe, and it's inconceivable to me that none of them will have trees of life as complex or even more complex than our own.
But that doesn't devalue the existence of OUR tree, because our tree is unique.
It consists of thousands of branches, all interdependent on thousands of others, and the precise structure depends on chance events, like the passage of the lemurs across the ocean 65 million years ago.
So when you go outside tomorrow, just take a look at a little piece of your world.
A corner of your garden, or a park, or even the grass that's growing in a crack in the pavement.
Because there will be life there, and it will be unique.
There will be nowhere like that anywhere else in the universe.
And that makes our tree, from the sturdiest branch to the most fragile twig, indescribably valuable.
"Underneath the Stars" by Kate Rusby Underneath the stars you met me And underneath the stars you left me I wonder if the stars regret me I'm sure they'd like me if they only met me They come and go of their own free will Go gently