Category
📺
TVTranscript
00:00In 2009, a new species of spider was identified.
00:28A spider with superpowers.
00:35It was named exactly 150 years after the publication of Darwin's On the Origin of Species,
00:50in which he explained why life on earth is so diverse and so complex.
00:55Darwin's theory of evolution by natural selection was built on the work of naturalists who were
01:09discovering thousands of new species across the world.
01:12That process of finding species new to science and naming them continues to this day,
01:22and it's recognised in the name of this newly discovered arachnid.
01:28Darwin's bark spider.
01:35The spider occupies a unique niche. It can hunt where no other spider can.
01:44That spider creates the largest webs found anywhere on earth,
01:48and in order to do that, it has to produce the strongest silk of any spider.
01:52They can span over 25 metres across lakes and rivers,
01:57and actually no one knows how they get their webs across such a large distance.
02:09But Darwin's bark spider is just one of thousands of unique species of animals and plants
02:15that you find in Madagascar.
02:18The rainforests here are one of the most biodiverse places on the planet.
02:31And each year, more discoveries are made as researchers try to understand why
02:36this tiny corner of the universe is so prolific.
02:42All of these living things were found within a five-minute walk of this field station,
02:46and the diversity is remarkable.
02:50There's a chameleon there.
02:52These are orchids. This big green leaf is a traveller's palm.
02:56There are four species of mushroom on that branch alone.
03:07Across Madagascar, there are over 14,000 species of plants.
03:12There are hundreds of species of mammals and birds and reptiles,
03:16and over 90% of them are unique to this island.
03:31How could it be that so many diverse living things,
03:35so beautifully adapted to their environment,
03:38could have emerged from a universe that's governed by a simple set of natural laws?
03:47The fact that we know the answer to that question
03:49is one of the greatest achievements in science.
03:53And in this film, I want to explore how these endless forms,
03:57most beautiful, have emerged from a lifeless cosmos.
04:46Africa, a whole continent full of creatures
04:50utterly different from those in Madagascar.
04:59But the diversity of life doesn't stop at what you see,
05:03because within each individual lies another hidden world of complexity.
05:16This, believe it or not, is the top predator in Africa.
05:19It's a huge predator.
05:21It's a huge predator.
05:22It's a huge predator.
05:24It's a huge predator.
05:25It's a huge predator.
05:27It's a huge predator.
05:28It's a huge predator.
05:29It's a huge predator.
05:31It's a huge predator.
05:32It's a huge predator.
05:34It's a huge predator.
05:35It's a huge predator.
05:37It's a huge predator.
05:38It's a huge predator.
05:40It's a huge predator.
05:41It's a huge predator.
05:42It's a huge predator.
05:44It's a huge predator.
05:45It's a huge predator.
05:47It's a huge predator.
05:48It's a huge predator.
05:50It's a huge predator.
05:51It's a huge predator.
05:52It's a huge predator.
05:54It's a huge predator.
05:56It's a huge predator.
05:57It's a huge predator.
05:59It's a huge predator.
06:00It's a huge predator.
06:02It's a huge predator.
06:04It's a huge predator.
06:05It's a huge predator.
06:07It's a huge predator.
06:08It's a huge predator.
06:10It's a huge predator.
06:12It's a huge predator.
06:13It's a huge predator.
06:16We have an animation called opsin which is bound to a pigment
06:19which allow her to see in colour and also allow her to see very well at night.
06:23which allow her to see in colour and also allow her to see very well at night.
06:35which are the things that allow her to run away.
06:47The proteins in a lion come in countless different forms.
06:53But they all share something in common.
06:57A backbone of carbon.
07:00An atom that's able to form long, complex molecules.
07:08Of all the 92 elements, there really is only one
07:12that has that appetite for bonding its four electrons
07:18to share them with other molecules.
07:20Carbon will share those electrons with nitrogen,
07:24with oxygen, with hydrogen,
07:26and, critically, with other carbon.
07:29It's these carbons to build up these immensely complex chains,
07:34the amino acids and the proteins,
07:36which are the building blocks of life.
07:40So, to understand our planet's endless diversity,
07:44we must begin by considering this life-giving element.
07:48I've got a few scratches now because of you.
07:51Because of your proteins.
07:54After all, to build a lion, you must first build carbon.
07:59And that's a story that stretches back to a time
08:02long before there were even stars in the universe.
08:1313.5 billion years ago,
08:16just a few hundred million years after the Big Bang,
08:20the universe was a carbon-free zone.
08:24An infinite, sterile gloom of hydrogen and helium clouds.
08:31Until, one day, those vast clouds began to collapse
08:35under the force of gravity.
08:42And long before the solar system, Earth, or life existed,
08:48the first stars were born.
08:54MUSIC PLAYS
09:09The birth of the first stars did much more than just illuminate the universe
09:13because that set in train a sequence of events
09:17which, ultimately, is necessary for the existence of life in the universe.
09:24MUSIC CONTINUES
09:28And we can still see that process playing out in the universe today.
09:37This is the brand-new South African Large Telescope.
09:48Its mirror is 11 metres wide,
09:51making it the largest optical telescope in the Southern Hemisphere.
09:57And it recently helped to pin down what's happening in an object
10:01some 650 million light-years from Earth.
10:10This beautiful, almost lifelike system is known simply as the bird.
10:17It's the spectacular result of what we used to think were two galaxies colliding.
10:27It's events happening in the head of the bird
10:29that are most interesting from the perspective of life in the universe
10:33because the head is formed by another galaxy, a third galaxy,
10:38an island of billions and billions of stars,
10:41colliding with the two galaxies that form the wings and the body
10:46at a speed of around 250 miles a second.
10:50Now, the turbulence, the disturbance that that creates
10:54is causing many new stars to be formed.
11:03These stars begin their lives by burning hydrogen
11:07to produce ever more helium.
11:11But as they age, as the hydrogen runs out,
11:14they lose more helium.
11:18The temperature at their core rises,
11:20increasing the chances of three helium nuclei fusing together
11:25to form a new element, carbon.
11:31That process has been going on for almost the entire history of the universe
11:36back 13 billion years,
11:38and it's the formation of stars that is the vital first step
11:44because stars produce the heavy elements in the universe,
11:48including carbon.
11:57From the universe's earliest times,
12:00carbon has been created inside ageing stars.
12:08And over time, this carbon has built up,
12:12drifting through the cosmos as dust
12:16until some of it was caught up
12:18in the formation of a planet called Earth.
12:27And it's here that we can see this ancient carbon
12:31brought vividly to life.
12:42Today, the universe is old enough
12:44that countless stars have lived and died,
12:47and so there's been plenty of time
12:49to synthesise the primordial hydrogen and helium
12:52into the heavy elements.
12:55The question now is,
12:57how does that carbon get into the web of life?
13:01Well, today, it enters via one ingredient.
13:06The ingredient is carbon dioxide,
13:09which plays a key role in photosynthesis.
13:15Each night, the carbon dioxide concentration increases,
13:19filling the air with carbon dioxide,
13:22which is then released into the atmosphere.
13:27The air is filled with carbon dioxide,
13:30which is then released into the atmosphere.
13:34Each night, the carbon dioxide concentration increases,
13:38filling the air around the leaves at the top of the trees.
13:45Now, this balloon has a carbon dioxide monitor in it
13:48which is going to measure the change in the levels of CO2
13:52at the top of the forest canopy as night turns to day.
13:57As the sun rises,
13:59the trees begin to photosynthesise.
14:03Now, at 6pm last night,
14:05so just after sunset,
14:07the concentration was around 350 parts per million.
14:11Around 10pm, so four hours after sunset,
14:14the concentration had risen to about 400 parts per million.
14:19And now, at about midday,
14:21the concentration has gone down to about 400 parts per million.
14:27The concentration back down to about 345 parts per million.
14:32So that's a variation over a period of 18 hours
14:36of, what, around 10% in the concentration of carbon dioxide
14:40just in that piece of atmosphere at the top of the forest canopy.
14:44So what you're seeing there is photosynthesis in action.
14:48Every day across the planet,
14:51photosynthesis uses sunlight
14:54to turn carbon dioxide and water into simple sugars.
15:02The overwhelming majority of the carbon
15:05is locked up inside long chains of sugar,
15:08molecules called cellulose and lignin.
15:12Now, lignin is the stuff that gives wood its strength.
15:16So in this form, and remember, that is most of it,
15:20it is very difficult indeed for animals to access.
15:28For the energy and nutrients locked away
15:30inside these long carbon chains
15:32to move through the food web,
15:34the carbon dioxide and water
15:36are the main sources of energy.
15:40And the best place to see that process in action
15:43is out on the open plain.
15:47It's one vast larder for all manner of organisms.
15:57But by far the most effective harvester of carbon,
16:01it's the food web.
16:04But by far the most effective harvester of carbon
16:08is actually one of the smallest creatures on the savannah.
16:17Termites are social insects
16:19working together to form a characteristic site
16:22seen all over the bush.
16:25That's a termite mound.
16:27Actually, it's a tip of the iceberg.
16:30The termite city extends way beyond that underground
16:34and its function is fascinating.
16:37It's essentially an air conditioning system.
16:40What it does is maintain very specific conditions
16:43inside the mound,
16:45the conditions of the rainforest.
16:50When the termites first colonised the savannah
16:53some 30 million years ago,
16:55they brought the rainforest with them
16:57to support a form of life
16:59that was already wonderfully adapted
17:01to living off dead wood.
17:03This is what these termite mounds are all about.
17:06Can you see those structures there,
17:08those white honeycomb-like structures?
17:11Those are called fungal combs.
17:13They are wood pulp
17:15and possibly bits of dead grass
17:17that the termites bring in
17:19and build into that structure.
17:21And the reason the conditions
17:23have to be the same as the rainforest
17:26is because they grow a particular
17:28genus of fungus
17:30called termitomyces
17:32around those honeycombs.
17:38The job of that fungus
17:40is to break down the lignin
17:42and the cellulose inside the wood
17:44and convert it into a form
17:46that the termites can eat
17:48which actually you can see there
17:50that are little white nodules
17:52just present on the honeycomb structure.
17:56The termites lack the enzymes
17:58to break down the wood efficiently
18:00so they've become farmers
18:02tending to one
18:04giant social stomach.
18:08So there's a very intense
18:10relationship between the termites
18:12and the fungus.
18:14You don't find that fungus anywhere else
18:16actually in the world
18:18as far as we know
18:20other than inside termite mounds.
18:26And it's thought that up to 90%
18:28of the carbon locked up
18:30in lignin in this part of Africa
18:32is released back into
18:34the food chain again
18:36solely by those termites
18:38and that fungus.
18:56So the termites
18:58deal with most of the lignin
19:00but that still leaves
19:02a vast store of carbon
19:04in the form of cellulose.
19:06Across Africa
19:08herds of mammals
19:10graze on grasses and leaves
19:12turning this cellulose
19:14into meat.
19:20Many are a type of mammal
19:22known as a ruminant
19:25the largest of which
19:27is one of the easiest animals
19:29to spot on safari.
19:55Giraffes live off a diet
19:57that's similar to termites.
19:59They eat cellulose
20:01primarily actually
20:03the tops of the acacia trees
20:05that you see here scattering
20:07the African savannah
20:09and they face that same problem
20:11they've got to break those
20:13difficult carbon bonds down
20:15and they come up with a very
20:17similar solution which is to
20:19cultivate bacteria
20:21and fungi
20:24but they do it inside their stomachs
20:26and ruminants
20:28like giraffes
20:30have had to build a very complex
20:32system in order to do that
20:34they've got four stomachs
20:36one of them contains their culture
20:38of bacteria and fungi
20:40and they allow them to digest
20:42that difficult cellulose.
20:48Even with all this hardware
20:50ruminants must feed
20:53for over two thirds of the day
20:59but there are other creatures here
21:01that have found a shortcut
21:03after all if plant fibres
21:05are hard to digest
21:07why not let someone else do the work
21:09and simply steal a meal
21:19He's coming for us
21:21Oh my god
21:35Look what we've just found
21:37We were out looking for a giraffe this morning
21:39we've found about ten of them
21:41just over there
21:43but in looking for the giraffe
21:45we've just found a leopard
21:47this is one of the top predators out here
21:50he's got very little to fear
21:52apart from other leopards and baby lions
21:54he's having a good look
21:56he certainly doesn't care about us
22:02he's around two years old
22:04and at the moment
22:06he doesn't have his own territory
22:08he's too young for that
22:10and so he's lying low
22:13He'll have to make about two kills a week
22:15to stay in good condition
22:17so maybe catch an impala
22:19every three or four days
22:21and he's obviously
22:23doing that
22:25because
22:27look at him
22:31Now he's looking for protein
22:35and I'm a little bit worried
22:37because I don't know
22:39if he's got enough protein
22:42and I'm a little bit worried
22:44because I'm protein
22:50He's coming really close to us
22:52because he's after the sound man's boom pole
22:54which is
22:56that's incredible
23:12From its origin
23:14in the death of stars
23:24it's capture
23:26by plants
23:34through insects
23:36mammals and on
23:39The carbon cycle
23:41is the real circle of life
23:49Out there tonight
23:51the relentless recycling of carbon
23:53through the food chain
23:55will continue
23:57as night falls
23:59you can almost see
24:01the cycle of life
24:03and the cycle of life
24:05and the cycle of life
24:07You can almost sense it
24:09the change in the sounds
24:11and the atmosphere
24:15Some will die
24:17so that others can live
24:19as carbon leaps
24:21from branch to branch
24:23across the great tree of life
24:25and guiding it
24:27on its way
24:29is just one very special
24:31form of chemistry
24:33Every living thing
24:36will be home for carbon atoms
24:38that existed long before
24:40there was life on earth
24:42and will exist long after
24:44Africa and earth are gone
24:50But the pattern of life
24:52the information needed
24:54to build a zebra
24:56or a tree
24:58or a human being
25:00or a lion
25:02persists, it's passed on
25:05A helical molecule
25:07with a backbone of carbon
25:09called DNA
25:35There was a time
25:37when earth appeared empty
25:53Yet despite appearances
25:553.8 billion years ago
25:57life was already underway
25:59in the form of tiny living specks
26:01that probably all shared
26:04the same biochemistry
26:06We know that every living thing
26:08on the planet today
26:10so every piece of food you eat
26:12every animal you've seen
26:14everyone you've ever known
26:16or will know
26:18in fact every living thing
26:20that will ever exist
26:22on this planet
26:24was descended from that one speck
26:27We call it the last universal
26:29common ancestor
26:31or LUCA
26:33So just as the universe
26:35had its origin at the Big Bang
26:37all life on this planet
26:39had its origin
26:41in that one moment
26:47Less than a billion years
26:49after its formation
26:51there was already life on earth
26:53It's possible that some of it
26:55used biochemistry
26:57utterly different from the life
26:59we see today
27:01If so
27:03it has long been extinct
27:07It's also possible
27:09that the first life
27:11may not have been cellular
27:13just living chemistry
27:15in the porous rocks
27:17of some ancient ocean
27:19It's also possible
27:22We're not sure
27:24but what's certain
27:26is that one day
27:28a population of organisms
27:30showed up with biochemistry
27:32that we would recognize
27:34This
27:36was LUCA
27:38The first expression of a form of life
27:40that would in time
27:42throw up a group of humans
27:44who left their mark
27:46in this part of Africa
27:49Now
27:51we don't know what LUCA
27:53looked like, we don't know
27:55precisely where it lived or how it lived
27:57but we do know this
27:59If you start to trace
28:01my ancestral line
28:03back to my parents
28:05to their parents, to their parents, to their parents
28:07all the way back
28:09through geological time scales
28:11over hundreds of thousands
28:13of millions and billions
28:15of years, there will be
28:17some broken line from me
28:19all the way back
28:21to LUCA
28:25We know that because
28:27every living thing on the planet today
28:29shares the same biochemistry
28:31We all have DNA
28:33It's made of the same bases
28:35A, C, T
28:37and G
28:39They code for the same amino acids
28:41Those amino acids build the same proteins
28:43which do very similar jobs
28:45whether you're a plant, a bacterium
28:47or a bipedal hominid
28:49like me
28:55So all life uses
28:57the same fundamental biology
29:01Those four bases
29:03A, C, G and T
29:05which code for just 20 amino acids
29:07which in turn
29:09build each and every one
29:11of life's proteins
29:15Be you bacteria
29:17plant, bug
29:19or beast
29:21your design comes from your DNA
29:25So it's this molecule
29:27that must hold the key
29:29to understanding why life today
29:31is so diverse
29:35We now know that the answer
29:37to the question, why is life on Earth so
29:39varied, is actually
29:41the answer to the question, why is the
29:43DNA molecule itself
29:45so varied? What are the natural
29:47processes that cause the
29:49structure of DNA to change?
29:51Well, part of the answer
29:53actually doesn't lie on Earth at all
29:55It lies up there
29:57amongst the stars
29:59and I can show you what I mean
30:01using this, which is
30:03a cloud chamber, a piece of apparatus
30:05that has a unique
30:07place in the history of physics
30:09I'm going to cool it down
30:11using dry ice
30:13frozen carbon dioxide
30:15just below minus 70 degrees
30:17Celsius
30:23I'll put the top on
30:27Hear that?
30:29That's the metal at the bottom of the tank
30:31cooling down very rapidly
30:33to minus 70
30:37The cloud chamber works by having
30:39a super-saturated
30:41vapour of alcohol
30:43inside the chamber
30:45Plenty on there
30:47Now, I want to get that alcohol
30:49I want to boil it off to get the vapour
30:51into the chamber, so I'm going to put a hot water
30:53bottle on top
30:55This is the first
30:57genuine particle physics detector
30:59It's the piece of apparatus
31:01that first saw antimatter
31:03and it really does consist
31:05only of a fish tank
31:07some alcohol, a bit of paper
31:09and a hot water bottle
31:33There, look at that
31:35cloud, that vapour trail
31:39That's a cosmic ray
31:41That was initiated
31:43by a particle
31:45probably a proton
31:47that hit the Earth's atmosphere
31:51It almost
31:53certainly originated
31:55outside our solar system
31:57and was accelerated by the magnetic fields
31:59of our galaxy
32:01It may even have begun its life
32:03beyond our galaxy
32:19Now, imagine
32:21if one of those hits the DNA
32:23of a living thing
32:25What that will do is cause a mutation
32:27That mutation
32:29may be detrimental
32:31or very, very occasionally
32:33it might be beneficial
32:39And I think it's quite
32:41wonderful to imagine
32:43that maybe
32:45one of the key mutations
32:47that was selected for over the millennia
32:49that led to some trait in me
32:51was caused by some
32:53particle that began its life
32:55perhaps in a massive supernova
32:57explosion
32:59outside our galaxy
33:01and went and hit the DNA of something
33:03and caused some kind of
33:05beneficial mutation
33:07We don't know, but you can dream, can't you?
33:17Mutations
33:19are an inevitable part of living
33:21on a planet like Earth
33:25They're the first hint
33:27that DNA and the genes
33:29that code for every living thing
33:31change from generation
33:33to generation
33:51Mutations are the spring
33:53from which innovation in the living world
33:55flows
33:59But cosmic rays
34:01are not the only way
34:03in which DNA can be altered
34:05There's natural background radiation
34:07from the rocks
34:09There's the action of chemicals
34:11and free radicals
34:13There can be errors when the code is copied
34:15and then all those changes
34:17can be shuffled by sex
34:19and indeed whole pieces of the code
34:21can be transferred from species
34:23to species
34:25So bit by bit, in tiny steps
34:27from generation to generation
34:29the code is constantly
34:31randomly changing
34:35Now whilst there's
34:37no doubt that random mutation
34:39does alter DNA
34:41evolution is anything
34:43but random
34:45It can't be, because the chances
34:47of something with DNA as complex
34:49as this, appearing by
34:51look alone, are vanishingly
34:53small
34:55Imagine you just changed one position
34:57in the code at random, a random
34:59mutation. There are four letters
35:01A, T, C and G, so there are
35:03four possible combinations
35:05If there are two places
35:07in the code, there are four combinations
35:09for each one, so that makes
35:1116. If there are three
35:13then there are 64 possibilities
35:15By the time you get
35:17to a code with 150
35:19letters in it, then there are more
35:21possible combinations
35:23in the code than there are atoms
35:25in the observable universe
35:29Now
35:31a hippo has a code
35:33with around 3 billion
35:35different letters
35:37So the number of combinations
35:39of those letters, the
35:41chances of producing that code
35:43at random are
35:45absolutely infinitesimally
35:47small. It's impossible
35:53So there must be
35:55a non-random element to evolution
35:57A natural
35:59process, which greatly
36:01restricts this universe of
36:03possibilities and shapes the
36:05outcome
36:07We call it natural selection
36:09And to see it
36:11in action, let's return to
36:13where we began, on the island
36:15of Madagascar
36:45Around
36:4765 million years ago, a group of
36:49seafarers were nearing the end of a long
36:51journey across the Indian Ocean
36:53These were
36:55accidental travellers, a group
36:57of creatures from Africa
36:59trapped on a natural raft
37:01and carried by the ocean currents
37:11The land they found
37:13was verging green territory
37:15Plants,
37:17insects, reptiles and birds
37:19had established themselves
37:21but there were none of their
37:23own kind
37:27They were caught up in a saga that
37:29tells of the great shifting of
37:31Earth's continental plates
37:39It's impossible to understand the diversity
37:41of life on Earth today without understanding
37:43the shifting geography of our
37:45planet
37:47Here's a map of Earth's southern
37:49hemisphere, as it was 150
37:51million years ago, and you see it's dominated
37:53by a single landmass
37:55called Gondwana
37:57And then, 90 million years ago
37:59Gondwana had begun
38:01to break up, to separate
38:03into something that looks
38:05quite recognisably like Africa
38:07And these two islands
38:09Madagascar and India
38:11Now, subsequently, India has
38:13drifted northwards and bumped
38:15into Eurasia, raising the Himalayas
38:17But, crucially,
38:19Madagascar has remained
38:21isolated. It's been
38:23an island surrounded by ocean
38:25for almost 90 million years
38:35So, when those seafarers
38:37arrived on their raft of
38:39trees and twigs and leaves
38:41they had a blank
38:43canvas. This two,
38:45three, maybe even a single
38:47pregnant individuals
38:49had a whole island to roam across
38:51And, over 65
38:53million years, they have
38:55blossomed into hundreds and
38:57thousands of individuals and become
38:59Madagascar's most iconic animals
39:07Madagascar
39:37Madagascar
39:39Madagascar
39:41Madagascar
39:43Finding the descendants
39:45of those ancient mariners is not easy
39:47But local guide
39:49Joseph has been tracking them for years
39:51and is going to help me
39:53find them
40:07There at the top of the tree
40:09is an Indri, which is the largest
40:11lemur in Madagascar
40:13And
40:15he's just sat there
40:17watching us
40:19quietly at the moment
40:25This lemur here is a very special
40:27lemur. He has a name
40:29He's called David
40:31And
40:33he has a name
40:35After
40:37Sir David Attenborough
41:05Now we can only do this because
41:07Joseph has spent a lot of time
41:09with these lemurs
41:11So they trust him
41:13And therefore it seems
41:15they trust me
41:36It's an enormous ant
41:41The reason it's thought that
41:43we find lemurs here in Madagascar
41:45and Madagascar alone is
41:47because there are no
41:49simians, there are no
41:51chimpanzees, none of my
41:53ancestral family
41:55dating back tens of millions of years
41:57to out-compete them
41:59So what's thought happened
42:01is that
42:03around 65 million years ago
42:05one of the lemurs'
42:07ancestors
42:09managed to sail across
42:11the Mozambique Channel
42:13and landed here
42:15There were none of those competitors here
42:17and so the lemurs have flourished
42:19ever since
42:21There are now over 90 species
42:23of lemur, or subspecies
42:25in Madagascar
42:27No species
42:29of my lineage
42:31The simians
42:45Over a vast
42:47sweep of time, the lemurs
42:49have diversified to fill
42:51all manner of different habitats
42:55From the arid, spiny
42:57forests of the south
42:59to the rocky canyons
43:01in the north
43:03There is something about this island
43:05that is allowing the lemurs' DNA
43:07to change in the most
43:09amazing ways
43:29We're on the hunt for an aye-aye
43:31the most closely
43:33related of all the surviving
43:35lemurs to their common ancestor
43:59I just shut the light off
44:01and saw these absolutely
44:03two bright, bright red eyes
44:05shining out
44:07very high up in the mist
44:13They're on all these sides
44:15in this forest
44:17which is very dark and dense
44:21The team have located
44:23a female aye-aye
44:25and her son
44:27They want to attach radio collars
44:29to track their movements
44:31and better understand how far
44:33they range through these forests
44:35But first
44:37they must sedate them
44:39with a dart
44:41What I'm trying to do
44:43is wait for it to come down low enough
44:45to get that clean shot
44:47I mean, how do you get a clean shot
44:49in this?
44:51I have no idea
44:58After two hours
45:00of traipsing through
45:02the treacherous forest
45:04the aye-ayes remain at large
45:28Well, here is the aye-aye
45:30that was tranquilized last night
45:32They finally got her
45:34about half an hour after we left
45:36I think it was probably
45:38because we were disturbing her
45:40Apparently, as soon as we'd gone
45:42she came down the tree
45:44and she was tranquilized
45:46And as you can see
45:48she's pretty well sedated now
45:50which is fortunate for me
45:52because she has certain adaptations
45:54that I wouldn't like to be deployed
45:56You can see there
45:58her teeth
46:00Her teeth are very unusual
46:02for a primate
46:04In fact, unique
46:06because they carry on growing
46:08So she's much more like a rodent
46:10in that respect
46:12And that's so she can gnaw into wood
46:14See, aye-ayes have filled
46:16a unique niche on Madagascar
46:18It's a niche that's filled
46:20by woodpeckers in many other areas
46:22of the world
46:24And to do that
46:26she has several unique adaptations
46:28of which her teeth are one
46:30The most startling
46:32is this central finger here
46:34It's bizarre
46:36It's got a ball and socket joint
46:38for a start
46:40So it has complete 360 degree movement
46:42It feels to me
46:44almost as if it's broken
46:46but it isn't
46:48You can move it around in any direction
46:50And she uses that finger initially
46:52to tap the trunk of the tree
46:54and then listening to the echo
46:56from that tapping
46:58with these huge ears
47:00she can detect where the grubs are
47:02And then she gnaws through the wood
47:04with those rodent-like teeth
47:06and then uses this finger again
47:08to reach inside the hole
47:10and get the bugs out
47:12So the question is
47:14why?
47:16How could an animal
47:18be so precisely adapted
47:20to this particular lifestyle?
47:22She's waking up now
47:24And the answer is
47:26natural selection
47:28See, what must have happened
47:30is way back
47:32when the ancestors of the lemurs
47:34the limeriforms arrived in Madagascar
47:36there must have been a mutation
47:38that lengthened
47:40the middle finger
47:42ever so slightly
47:44of one of those lemurs
47:46and that must have given it an advantage
47:48to reach into little holes
47:50and search for grubs
47:52There's some reason why that lengthened middle finger
47:54meant that that gene
47:56was more likely to be passed
47:58to the next generation
48:00and then down to the next generation
48:02So that landscape of possibilities
48:04is narrowed
48:06because that gene persists
48:08and it's persisted now
48:10for at least 40 million years
48:12because this species
48:14has been on one branch
48:16tree of life now
48:18for over 40 million years
48:20and so over those years
48:22that middle finger has got more and more specialised
48:26Natural selection
48:28has allowed the aye-aye's wonderfully
48:30mutated finger to spread
48:32through the population
48:36And this same law applies to all life
48:40If you have a mutation
48:42that helps you in the struggle to survive
48:44you are more likely to leave more offspring
48:46and in the next generation
48:48that mutation
48:50is more likely to survive
48:56So this animal
48:58is a beautiful example
49:00probably one of the best in the world
49:02of how the sieve
49:04of natural selection
49:06produces animals that are perfectly adapted
49:08to live in their environment
49:14There are many reasons
49:16to study the aye-aye
49:18but here's a good one
49:20In the 1970s
49:22it was thought the aye-aye
49:24was extinct
49:26Now we know
49:28there are many reasons
49:30to study the aye-aye
49:32but here's a good one
49:34In the 1970s
49:36it was thought the aye-aye
49:38was extinct
49:40Now we know
49:42there are several thousand
49:44in the forest of Madagascar
49:465, 6, 7 thousand
49:48certainly less than 10 thousand
49:50but over the last 50 years
49:5250% of this forest has vanished
50:08This is an animal
50:10that's been around as a species
50:12for over 40 million years
50:14so
50:16it's important to know
50:18how these animals are doing
50:20and how they're surviving
50:22in this diminishing habitat
50:24The aye-aye
50:38Whilst natural selection
50:40explains how the aye-aye evolved
50:42it alone
50:44can't explain how a small group
50:46of individuals over 60 million
50:48years ago
50:50gave rise to over 90 different
50:52species of lemur today
50:58But there is another form of life
51:00that can offer us a clue
51:04Up here in the high forest canopy
51:06we're in a very different environment
51:08to the one down there
51:10on the forest floor
51:12It's a more arid environment
51:14It's almost like a desert
51:16It's exposed to the sun
51:18Water is harder to come by
51:20This is a sea of different niches
51:22that are able to be occupied
51:24and exploited
51:26by animals that are different
51:28to the ones you'll find down there
51:30on the floor
51:32So in a very real sense
51:34this is an island
51:36an island to be colonised
51:38And sure enough
51:40there are settlers to be found
51:42even here
51:44You see that thing
51:46that looks like a muddy ball
51:48That's an ant's nest
51:50It's home to a species of chromatogaster ants
51:52that are unique
51:54not only to Madagascar
51:56but to the forest canopy
51:58You see what makes those ants unique
52:00is that they can build their own nests
52:02There are very few species of ants
52:04that can do that
52:06So that is an island
52:08that is a niche
52:10and it's allowed that species of ants
52:12to develop because they're isolated
52:14from the rest of the ecosystem
52:16And astonishingly
52:18within this niche
52:20another form of life
52:22new to science has been discovered
52:26A beetle
52:28that manages to survive here
52:30unharmed by the ants
52:32How it does it
52:34is a mystery
52:36But what is known
52:38is that this particular species
52:40has only ever been found
52:42inside these nests
52:44So that really is
52:46its own mini ecosystem
52:48with species living in it
52:50that are unique to that island
53:04We live on an ever-shifting
53:06dynamic world
53:08that creates islands
53:10in abundance
53:14Earth's mountain ranges
53:16river valleys
53:18and canyons
53:20all create islands
53:22for life
53:28And it's these islands
53:30that those ancestors of the lemurs
53:32found when they arrived
53:34in Madagascar
53:45Empty niches
53:47where populations became isolated
53:49and over great swathes
53:51of time
53:53evolved into such wonderfully
53:55diverse forms
54:15150 years on
54:17from the origin of species
54:19the subtlety
54:21and beauty of Darwin's insight
54:23is still revealing itself to us
54:28It describes
54:30how our beautiful
54:32complex tree of life
54:34has grown from a once
54:36desolate universe
54:38The chemistry of carbon
54:40allows for the existence
54:42of a molecule
54:44that is able to replicate itself
54:46and pass information on
54:48from generation to generation
54:50There can be random changes
54:52in the structure of that molecule
54:54mutations
54:56and they are tested
54:58by their interaction
55:00with the environment
55:02and other living things
55:04The ones that pass that test
55:06survive and the ones
55:08that fail that test are lost
55:10The separation and isolation
55:12of living things onto islands
55:14which may be physical
55:16like Madagascar
55:18or just the single branch
55:20of a single tree
55:22results in speciation
55:24the explosion of living forms
55:26highly specialized to occupy
55:28niches within niches
55:30and this is the explanation
55:32for the diversity of life on Earth
55:34There is grandeur
55:36in this view of life
55:38and understanding
55:40how it happened
55:42surely only adds to the wonder
55:52As precise as Einstein's
55:54theories of relativity
55:56and as profound as thermodynamics
56:00Darwin has given us
56:02another universal law
56:08evolution by natural selection
56:20and if evolution is the law
56:22on this island
56:24then it will apply
56:26throughout the cosmos
56:30which begs a big question
56:32Could there be other
56:34trees of life
56:36most beautiful
56:38amongst the stars?
56:48In 2011
56:50we discovered a rocky planet
56:52orbiting around a distant star
56:54with daytime temperatures
56:56not too dissimilar
56:58to those found on Earth
57:00Now there must be
57:02millions if not billions
57:04of such planets out there
57:06in the universe
57:08and it's inconceivable to me
57:10that none of them will have
57:12trees of life as complex
57:14or even more complex
57:16than our own
57:18but that doesn't devalue
57:20the existence of our tree
57:22because our tree is unique
57:24it consists of thousands
57:26of branches all interdependent
57:28and the precise structure
57:30depends on chance events
57:32like the passage of the lemurs
57:34across the ocean 65 million years ago
57:44So when you go outside tomorrow
57:46just take a look at a little
57:48piece of your world
57:50a corner of your garden
57:52or a park
57:54or even the grass that's growing
57:56it's unique in the pavement
57:58because there will be life there
58:00and it will be unique
58:02there will be nowhere like that
58:04anywhere else in the universe
58:06and that makes our tree
58:08from the sturdiest branch
58:10to the most fragile twig
58:12indescribably valuable
58:26I wonder if the stars will laugh at me
58:30I wonder if the stars regret me
58:34I'm sure they'd like me if you only met me
58:40Stay with BBC HD tonight
58:42for highlights of the Man U game
58:44versus Everton and Aston Villa
58:46up against West Ham
58:48Match of the Day 2 is coming up next