0:00:14 > 0:00:20I'm on a fantastic journey to look for the origins of life.
0:00:20 > 0:00:24I shall be travelling not only around the world, but back in time,
0:00:24 > 0:00:26to try and build a picture
0:00:26 > 0:00:30of what life was like in that very early period.
0:00:31 > 0:00:34It will be a journey full of wonders.
0:00:34 > 0:00:37Parts of it were unknown until only a few years ago.
0:00:37 > 0:00:42In 50 years of programme-making, I've been lucky enough to explore
0:00:42 > 0:00:45the living world in all its splendour and complexity.
0:00:49 > 0:00:55The blue whale! The biggest creature that exists on the planet!
0:00:59 > 0:01:03Now, I'm off to explore the origins of all this.
0:01:03 > 0:01:07To look for the very first living creatures that appeared on the planet.
0:01:10 > 0:01:15In recent years, scientists have unearthed dramatic evidence of what those first creatures were like.
0:01:15 > 0:01:20We can also find clues in living animals.
0:01:22 > 0:01:25And this enchanting little creature
0:01:25 > 0:01:27is what we were looking for.
0:01:27 > 0:01:32Using the latest technology, it's possible to bring those first animals to life
0:01:32 > 0:01:36for the first time in half a billion years.
0:01:37 > 0:01:40From the moment they appeared
0:01:40 > 0:01:43to the time that they took their pioneering steps on land,
0:01:43 > 0:01:47we can deduce how animals acquired bodies that move,
0:01:47 > 0:01:52eyes that saw and mouths that ate.
0:01:55 > 0:01:59And we can understand how those first organisms
0:01:59 > 0:02:03laid the foundations for modern animals as we know them today.
0:02:05 > 0:02:07Hello, old boy. How are you?
0:02:07 > 0:02:10'Including you and me.'
0:02:20 > 0:02:25My 40,000 mile journey begins very close to home, in Britain.
0:02:26 > 0:02:32This is the Charnwood Forest in Leicestershire in the middle of England.
0:02:32 > 0:02:35As a schoolboy, I grew up near here.
0:02:35 > 0:02:38And in these rocks, a discovery was made
0:02:38 > 0:02:41that transformed our understanding
0:02:41 > 0:02:45of that mystery of mysteries, the origin of life.
0:02:50 > 0:02:55The history of life can be thought of as a many-branched tree,
0:02:55 > 0:02:57with all the species alive today
0:02:57 > 0:03:00related to common ancestors down near the base.
0:03:02 > 0:03:08The five kingdoms of life, the main branches, were established early on.
0:03:08 > 0:03:11Bacteria.
0:03:11 > 0:03:14Protists - amoeba-like creatures.
0:03:16 > 0:03:18Fungi.
0:03:19 > 0:03:23Plants.
0:03:23 > 0:03:28And animals. That for me is the most fascinating question of all.
0:03:28 > 0:03:33How and when did they first appear?
0:03:33 > 0:03:36The answers are only now beginning to emerge -
0:03:36 > 0:03:41and some of the first clues came from here in Charnwood Forest.
0:03:42 > 0:03:46I was a passionate fossil collector.
0:03:46 > 0:03:50But I never came to look for them in this part of Charnwood,
0:03:50 > 0:03:54because the rocks here are among the most ancient in the world.
0:03:54 > 0:03:56Around 600 million years old, in fact.
0:03:56 > 0:04:01And every geologist knew or at least was convinced that rocks of
0:04:01 > 0:04:07such extreme age couldn't possibly contain fossils of any kind.
0:04:07 > 0:04:12And then a boy from my very own school, just a few years after I left it,
0:04:12 > 0:04:15made an astounding discovery.
0:04:16 > 0:04:19Against all the predictions of scientific know-alls,
0:04:19 > 0:04:24he found a fossil in these ancient Leicestershire rocks.
0:04:24 > 0:04:27And this is it.
0:04:27 > 0:04:32It's called and is known around the world as Charnia,
0:04:32 > 0:04:35after the forest in which it was discovered.
0:04:35 > 0:04:36But what is it?
0:04:36 > 0:04:39Is it animal or plant?
0:04:39 > 0:04:42The fact is it comes from such a remote period
0:04:42 > 0:04:47that the distinction between those two forms of life was not yet clear.
0:04:47 > 0:04:49But one thing is certain.
0:04:49 > 0:04:51It clearly was alive.
0:04:53 > 0:04:57Charnia was a marine organism, part of an ancient community
0:04:57 > 0:05:02of living things that lived in darkness at the bottom of an ocean.
0:05:02 > 0:05:05That much we do know.
0:05:05 > 0:05:08But what was this strange creature?
0:05:08 > 0:05:11When did it first appear?
0:05:11 > 0:05:14And how is it related to modern animals?
0:05:14 > 0:05:18The answers to these questions are only now beginning to emerge.
0:05:21 > 0:05:26There were further finds in Charnwood forest, like this disk,
0:05:26 > 0:05:28which was probably the holdfast
0:05:28 > 0:05:32which secured the frond of Charnia to the sea floor.
0:05:32 > 0:05:37And then people began to look in rocks of this great age
0:05:37 > 0:05:39all around the world.
0:05:39 > 0:05:43And lo and behold they discovered a whole range of fossils
0:05:43 > 0:05:48that enable us now to put together in extraordinary detail
0:05:48 > 0:05:51the first chapters in the history of life.
0:05:51 > 0:05:56That all happened a very long time ago.
0:05:56 > 0:06:00Imagine travelling back through time.
0:06:09 > 0:06:15Humans have been around for two million years.
0:06:15 > 0:06:21The dinosaurs were wiped out 65 million years ago.
0:06:28 > 0:06:32Charnia is more than eight times older than the oldest dinosaur.
0:06:32 > 0:06:36It lived about 560 million years ago.
0:06:39 > 0:06:44But compared with the age of life itself, that's nothing.
0:06:44 > 0:06:48Before Charnia and other complex organisms existed,
0:06:48 > 0:06:53the only living things were microscopic single cells.
0:06:53 > 0:06:57They first appeared about three and a half billion years ago
0:06:57 > 0:07:00when the Earth was a very different place.
0:07:05 > 0:07:07The early continents were still forming.
0:07:10 > 0:07:14The days were a mere six hours long, because at that time
0:07:14 > 0:07:19the Earth was spinning much faster on its axis than it does today.
0:07:29 > 0:07:33The land was dominated by volcanoes -
0:07:33 > 0:07:36hostile and lifeless.
0:07:45 > 0:07:50But deep in the oceans, life had begun.
0:07:50 > 0:07:55The latest theory is that chemicals spewing from underwater volcanic vents
0:07:55 > 0:07:59solidified and created towers like these,
0:07:59 > 0:08:03and this produced the conditions needed for the first cells to form.
0:08:05 > 0:08:12Some of these began to harness the energy of sunlight, just as plants do today, and formed colonies.
0:08:13 > 0:08:17These rocky stromatolites in western Australia
0:08:17 > 0:08:21have been constructed by very similar photosynthesising bacteria.
0:08:27 > 0:08:31Others managed to survive by extracting nourishment directly
0:08:31 > 0:08:37from the environment, like the fungi and animals that would later evolve.
0:08:42 > 0:08:47This state of affairs continued for a vast period of time.
0:08:51 > 0:08:57For some three billion years, simple microscopic organisms
0:08:57 > 0:09:00were the most advanced form of life on the planet.
0:09:00 > 0:09:05That's way over half the entire history of life on Earth.
0:09:05 > 0:09:10And then suddenly, within the space of a few million years, a mere
0:09:10 > 0:09:15blink of the eye in evolutionary terms, advanced organisms appeared.
0:09:15 > 0:09:18Why is a mystery,
0:09:18 > 0:09:24but we may find some clues to it on the coastline down here.
0:09:25 > 0:09:30On the Eastern coast of Canada, there is evidence of an event that
0:09:30 > 0:09:34may well have been the spark that started the evolution of animals.
0:09:36 > 0:09:41These rocks have been dated by radioactivity
0:09:41 > 0:09:45to just before the moment that life became very complex.
0:09:45 > 0:09:51So if we can understand the circumstances under which these rocks were formed,
0:09:51 > 0:09:56we may get a clue as to why it was that life suddenly became more complex.
0:09:58 > 0:10:04Fragments of red stone are embedded in the darker rock.
0:10:04 > 0:10:06They look out of place.
0:10:06 > 0:10:08And, in fact, they are.
0:10:10 > 0:10:13Geologists call them drop stones.
0:10:13 > 0:10:18They were transported here by glaciers.
0:10:18 > 0:10:19As the ice moved off the land,
0:10:19 > 0:10:22it floated out over the sea in a great shelf,
0:10:22 > 0:10:26carrying with it stones that it had gathered on the continents.
0:10:26 > 0:10:28And when the ice eventually melted,
0:10:28 > 0:10:32the stones fell into the sediments on the sea floor.
0:10:32 > 0:10:35This wasn't the only place covered by ice.
0:10:35 > 0:10:40Drop stones of the same age have been found in deposits all over the world.
0:10:41 > 0:10:46The evidence points to a global spread of glaciation.
0:10:46 > 0:10:51Just before complex life appeared, the world was in the grip
0:10:51 > 0:10:54of the biggest ice age in its entire history.
0:11:29 > 0:11:33It's been called Snowball Earth.
0:11:37 > 0:11:40The Earth was plunged into a deep freeze
0:11:40 > 0:11:43so severe it probably extended
0:11:43 > 0:11:44from pole to pole.
0:11:44 > 0:11:47The surface of the seas were frozen over.
0:11:47 > 0:11:51On the continents, ice caps and glaciers developed.
0:11:51 > 0:11:55In places, the ice was probably a kilometre or so thick.
0:11:55 > 0:11:59We still don't know enough about the details, but it's likely that
0:11:59 > 0:12:03those conditions lasted for millions of years.
0:12:07 > 0:12:12Stromatolites and similar bacterial colonies that dominated the Earth
0:12:12 > 0:12:15were crushed under the advancing glaciers.
0:12:20 > 0:12:25Life was nearly annihilated before it had truly begun.
0:12:29 > 0:12:34It's difficult to imagine how life managed to survive in those circumstances.
0:12:34 > 0:12:37But survive it did.
0:12:42 > 0:12:44Microbiologist Dr Hazel Barton
0:12:44 > 0:12:49believes that modern glaciers can tell us how it did so.
0:12:51 > 0:12:55She has come to the Columbia Icefield in the Rocky Mountains
0:12:55 > 0:13:01in search of organisms that are still able to endure such extremes today.
0:13:01 > 0:13:02The thing about being here
0:13:02 > 0:13:05is it looks like everything's been wiped clean,
0:13:05 > 0:13:08the glacier's come through and it's destroyed all life,
0:13:08 > 0:13:10there's nothing living.
0:13:10 > 0:13:12But to a microbiologist this looks a bit like a rainforest.
0:13:12 > 0:13:16From here you can see discolouration on the surface of the ice,
0:13:16 > 0:13:18but that's not dirt -
0:13:18 > 0:13:22that is photosynthetic bacteria that are surviving there
0:13:22 > 0:13:24and that creates an ecosystem where you have plants
0:13:24 > 0:13:28and you have predators come in and feed on those organisms.
0:13:28 > 0:13:31So even though it looks dead, it's actually wildly alive with life.
0:13:33 > 0:13:37The kind of life you can see here is pretty ancient.
0:13:37 > 0:13:41They've had to adapt to a lot of global catastrophes.
0:13:41 > 0:13:44They had to adapt to Snowball Earth.
0:13:45 > 0:13:49Microorganisms that live in these harsh environments we call extremophiles.
0:13:49 > 0:13:55They have an amazing amount of adaptability that's hardwired in their genomes.
0:13:55 > 0:13:59You can freeze them, you can bury them a mile down in ice
0:13:59 > 0:14:02and its not much of a hindrance because of their adaptable nature.
0:14:06 > 0:14:12We owe our existence to ice-dwelling extremophiles.
0:14:12 > 0:14:15Snowball Earth almost extinguished life,
0:14:15 > 0:14:20but tiny organisms like these hung on for millions of years.
0:14:22 > 0:14:24I think what you had is
0:14:24 > 0:14:27organisms that could withstand extreme environments
0:14:27 > 0:14:30conditioning themselves to this changing ecosystem.
0:14:30 > 0:14:33You had a skin of microbes on the surface of the planet,
0:14:33 > 0:14:38and you had these organisms living between where the, the glaciers contacted the rock,
0:14:38 > 0:14:41and that was enough life trickling over so that
0:14:41 > 0:14:45when those conditions retreated, and it became more favourable,
0:14:45 > 0:14:48then it was like, pff, and everything took off again.
0:14:56 > 0:14:59Finally, Snowball Earth began to warm.
0:15:05 > 0:15:08There is evidence that around this time,
0:15:08 > 0:15:12there was a global surge in volcanic activity.
0:15:16 > 0:15:21Eruptions punched through the ice, spewing carbon dioxide into the air.
0:15:25 > 0:15:29As it spread through the atmosphere, it produced a greenhouse effect,
0:15:29 > 0:15:34trapping heat so that the earth warmed and the ice melted.
0:15:55 > 0:15:58We still have a lot to discover about what happened next,
0:15:58 > 0:16:03but it seems likely that it was the melting of Snowball Earth
0:16:03 > 0:16:06that led to the next great development of life.
0:16:18 > 0:16:21As the glaciers retreated,
0:16:21 > 0:16:26so nutrient-rich meltwater flooded into the oceans.
0:16:41 > 0:16:47For the surviving cells, this flood of ground-up rock was a bonanza.
0:16:47 > 0:16:51For the microbes that could photosynthesise,
0:16:51 > 0:16:54the pulverised rock was a potent fertiliser.
0:16:54 > 0:17:01And their growth would have a direct influence on early animal cells.
0:17:01 > 0:17:05Cyanobacteria and other oxygen-producing microbes
0:17:05 > 0:17:08began to bloom across the globe.
0:17:11 > 0:17:15These flourished in colonies of plant-like microbes
0:17:15 > 0:17:18that pumped out enormous volumes of oxygen.
0:17:20 > 0:17:22And it was this increase in oxygen
0:17:22 > 0:17:26that was the key to the rise of the animal kingdom.
0:17:28 > 0:17:31Now, simple microscopic life
0:17:31 > 0:17:36had the fuel it needed to develop into something bigger.
0:17:40 > 0:17:44After billions of years of single-celled life,
0:17:44 > 0:17:47something amazing happened in the deep sea.
0:17:49 > 0:17:54Up to this moment, living cells that had been produced by division
0:17:54 > 0:17:57simply drifted away from one another.
0:18:01 > 0:18:04But now, with the aid of increased oxygen,
0:18:04 > 0:18:07some cells were sticking together.
0:18:09 > 0:18:13Some of these clumps ultimately evolved into animals.
0:18:15 > 0:18:18To find out how oxygen drove this process,
0:18:18 > 0:18:21I have come to Australia's Barrier Reef,
0:18:21 > 0:18:24to look at one of the most primitive of animals alive today -
0:18:24 > 0:18:27one that can truly be called a living fossil.
0:18:30 > 0:18:34It is one of the simplest multi-celled organisms that we know,
0:18:34 > 0:18:37but its basic body structure has nonetheless enabled it
0:18:37 > 0:18:43to survive virtually unchanged for around 600 million years.
0:18:43 > 0:18:45It's a sponge.
0:18:45 > 0:18:50Sponges are just collections of simple cells
0:18:50 > 0:18:53that have clumped together and got stuck together.
0:18:53 > 0:18:57They don't have a digestive system or a nervous system
0:18:57 > 0:18:59or a blood circulatory system,
0:18:59 > 0:19:02and they get their food and their oxygen
0:19:02 > 0:19:07by just pumping seawater through channels in the body.
0:19:07 > 0:19:12But they can give us an indication of how it was that cells
0:19:12 > 0:19:17first clumped together to form bodies of any real size.
0:19:19 > 0:19:22At the microscopic level, sponge cells are bound together
0:19:22 > 0:19:28by a tangle of hairy, stringy protein molecules called collagen.
0:19:29 > 0:19:35This collagen glue is found only animals, and nowhere else.
0:19:37 > 0:19:43Collagen is sometimes called the sticky tape of the animal world.
0:19:43 > 0:19:46It's the commonest protein in our body.
0:19:46 > 0:19:49It forms the framework of our skins.
0:19:49 > 0:19:52Plastic surgeons use it to pump up our lips.
0:19:52 > 0:19:56You need oxygen to manufacture collagen
0:19:56 > 0:19:59and with the rising amount of oxygen in the atmosphere
0:19:59 > 0:20:04at the end of Snowball Earth, cells were able to manufacture it.
0:20:07 > 0:20:11At the Research Station on Heron Island on the Great Barrier Reef,
0:20:11 > 0:20:13scientists are working to understand
0:20:13 > 0:20:16how it was that multi-celled organisms
0:20:16 > 0:20:18began to colonise the earth.
0:20:19 > 0:20:23To find the answer, marine biologist Professor Bernard Degnan
0:20:23 > 0:20:27is studying sponges.
0:20:27 > 0:20:30The things that connect sponges to the rest of the animal kingdom
0:20:30 > 0:20:34we can find at the level of the cell and the gene.
0:20:34 > 0:20:38When we look at its genes, it's clearly an animal.
0:20:38 > 0:20:41We look for the things that bind all animals together,
0:20:42 > 0:20:45so what does a human share not only with a chimpanzee
0:20:45 > 0:20:49and for that matter a tiger but what it shares with a sponge.
0:20:50 > 0:20:52If we can find any common threads,
0:20:52 > 0:20:55we're getting really to the heart of the matter of multicellularity
0:20:55 > 0:20:58in the animal kingdom, so that's the key.
0:21:02 > 0:21:06A classic experiment gives us some insight.
0:21:06 > 0:21:11First, a sponge is cut into small pieces.
0:21:17 > 0:21:21Then it is pushed through a sieve on the end of a syringe.
0:21:21 > 0:21:25This breaks the animal down into its individual cells.
0:21:29 > 0:21:33This may seem a brutal thing to do to a living organism,
0:21:33 > 0:21:36but to a sponge this is of no consequence.
0:21:39 > 0:21:44In response, it does something quite astonishing.
0:21:46 > 0:21:50The cells begin to move...
0:21:50 > 0:21:53and then they form clumps.
0:21:55 > 0:21:58Soon the clumps form bigger clumps,
0:21:58 > 0:22:05until three weeks later, a miniature sponge has formed.
0:22:05 > 0:22:10Sponges have this amazing capacity to regenerate themselves.
0:22:12 > 0:22:15And what we can do is actually rebuild a sponge
0:22:15 > 0:22:17from the cell level up.
0:22:24 > 0:22:27From this experiment, we can maybe infer a few things
0:22:27 > 0:22:31that happened 600 million years ago with the very first animals.
0:22:31 > 0:22:36We can infer that there were cells coming together,
0:22:36 > 0:22:39they could adhere to each other, they used extracellular proteins
0:22:39 > 0:22:43like collagen to glue themselves together.
0:22:43 > 0:22:46They had the ability to communicate with each other
0:22:46 > 0:22:50and a certain amount of flexibility that allowed them to interact
0:22:50 > 0:22:54to give rise to something that's bigger and greater,
0:22:54 > 0:22:58a large macroscopic multicellular animal.
0:22:59 > 0:23:04The advantages of being multi-celled were many.
0:23:04 > 0:23:06Colonies of cells could collect more food,
0:23:06 > 0:23:09control their internal environment
0:23:09 > 0:23:12and act efficiently by working as a team.
0:23:14 > 0:23:16It was just the beginning.
0:23:19 > 0:23:21In Canada, there is an extraordinary place
0:23:21 > 0:23:24that reveals what happened next.
0:23:25 > 0:23:30Here you can see how just a few million years after the melting of Snowball Earth,
0:23:30 > 0:23:35the earliest multi-celled organisms became much more sophisticated...
0:23:35 > 0:23:37and much bigger.
0:23:41 > 0:23:44This is Mistaken Point in Newfoundland.
0:23:44 > 0:23:50It got that name because in years gone by sailors coming up the eastern coast of North America
0:23:50 > 0:23:52but lost in the fogs that are so frequent here
0:23:52 > 0:23:55would head north for the open ocean
0:23:55 > 0:23:57but be wrecked on these savage rocks.
0:23:59 > 0:24:05But today Mistaken Point has a completely different reputation.
0:24:05 > 0:24:07Today it is recognized as one of
0:24:07 > 0:24:13the most important fossil-bearing sites in all the world.
0:24:13 > 0:24:17For here you can see fossils
0:24:17 > 0:24:22of the very first animals that evolved on this planet.
0:24:36 > 0:24:41The fossils in these rocks are both wonderful and bizarre.
0:24:45 > 0:24:47When the sun is low in the sky,
0:24:47 > 0:24:51the slanting light shows up their structure in great detail.
0:24:54 > 0:24:56Organisms were no longer
0:24:56 > 0:25:01just clumps of undifferentiated cells, like sponges.
0:25:01 > 0:25:05They were organized into defined shapes.
0:25:05 > 0:25:09And among them are some that look exactly like Charnia
0:25:09 > 0:25:13that had been first recognised in Charnwood Forest.
0:25:15 > 0:25:19Here, there are not only hundreds of examples of Charnia,
0:25:19 > 0:25:22but a whole community of other strange creatures.
0:25:22 > 0:25:27Everywhere you look there are complex markings and indentations
0:25:27 > 0:25:29of one kind or another -
0:25:29 > 0:25:33it's almost as though children have been playing in wet sand.
0:25:33 > 0:25:37It's like walking through a carpet of ancient creatures.
0:25:37 > 0:25:42It's difficult to imagine that 565 million years ago
0:25:42 > 0:25:45this was the bottom of the ocean
0:25:45 > 0:25:49and these were some of the first animals to live on this planet.
0:26:04 > 0:26:07Here at Mistaken Point,
0:26:07 > 0:26:11exceptional conditions have preserved these delicate life forms.
0:26:16 > 0:26:19Each one of these layers of rock
0:26:19 > 0:26:24was once mud lying at the bottom of an ocean.
0:26:25 > 0:26:29An ocean so deep it was very cold,
0:26:29 > 0:26:31and very poor in oxygen,
0:26:31 > 0:26:36so any organism that died here took a very long time to decay.
0:26:36 > 0:26:40But those that did have been preserved
0:26:40 > 0:26:43with an astonishing degree of perfection.
0:26:43 > 0:26:46What makes this place so different?
0:26:50 > 0:26:55There was a volcano rising from the sea floor close by,
0:26:55 > 0:26:58and it spewed out millions of tons of ash.
0:27:09 > 0:27:11The ash sank to the bottom,
0:27:11 > 0:27:15blanketing everything like a sub-marine Pompeii.
0:27:17 > 0:27:22Over millions of years, the ash itself was buried by muddy sediments
0:27:22 > 0:27:25and then all was turned into rock.
0:27:25 > 0:27:28And then, over hundreds of millions of years,
0:27:28 > 0:27:32mountain-building forces thrust the whole sea-floor upwards
0:27:32 > 0:27:35to its present position on the coast of Canada.
0:27:38 > 0:27:42Dr Guy Narbonne is a world expert on the fossils of Mistaken Point.
0:27:45 > 0:27:48What you can see on this surface
0:27:48 > 0:27:52is the grey is the muddy sea bottom
0:27:52 > 0:27:55and this is where the creatures all lived.
0:27:55 > 0:28:01And they were knocked down and covered by a bed of volcanic ash.
0:28:01 > 0:28:06And you can see it here and all of this pink and white
0:28:06 > 0:28:09speckled stuff is volcanic ash.
0:28:09 > 0:28:12The volcanic ash cast every part of them,
0:28:12 > 0:28:16like putting plaster around your arm if you break it,
0:28:16 > 0:28:20and that led to a perfect preservation
0:28:20 > 0:28:23of every detail of the outside.
0:28:25 > 0:28:29Radioactivity in this light-coloured ash layer
0:28:29 > 0:28:33allows Guy Narbonne to date precisely the eruptions,
0:28:33 > 0:28:35and therefore the fossils.
0:28:35 > 0:28:40Some are as old as 579 million years.
0:28:40 > 0:28:44Here we can see one of the best of the fossils on the surface.
0:28:44 > 0:28:50It consists of disks, and they all have these pustules
0:28:50 > 0:28:55on them and that's why we rather affectionately call them pizza disks.
0:28:55 > 0:28:58And they were very simple in form,
0:28:58 > 0:29:03but the first truly large creatures in Earth evolution.
0:29:06 > 0:29:10The pizza discs are only one of the species found here.
0:29:13 > 0:29:18Most are fern-like fronds, like this enormous species of Charnia.
0:29:21 > 0:29:23This is a two-metre-long frond.
0:29:23 > 0:29:26- Astounding! - And this is not the biggest.
0:29:26 > 0:29:29We have about 200 specimens of this here.
0:29:31 > 0:29:35The frond of Charnia found in Charnwood was isolated.
0:29:37 > 0:29:43But here at Mistaken Point, a whole community of organisms has been preserved together...
0:29:43 > 0:29:48and that could give us new information.
0:29:48 > 0:29:52You're calling this an animal but is it justified to call it an animal?
0:29:52 > 0:29:54- Well...- It's rather plant-like.
0:29:54 > 0:29:57Well, "What is it?" is a big question.
0:29:57 > 0:30:00We know for a fact it can't be a plant
0:30:00 > 0:30:03because we're in water thousands of metres deep,
0:30:03 > 0:30:06there wouldn't have been enough light to read a newspaper.
0:30:06 > 0:30:11We're several orders of magnitude too little light for photosynthesis.
0:30:11 > 0:30:14OK, so it's not photosynthesising because it's too deep
0:30:14 > 0:30:17and therefore it's not a plant. What's it living on?
0:30:17 > 0:30:23What we believe they're living on is dissolved carbon and other nutrients in the deep oceans.
0:30:23 > 0:30:29So it's absorbing these nutrients through its entire body.
0:30:29 > 0:30:34Very thin. Probably not much thicker than your thumbnail.
0:30:34 > 0:30:37Very primitive.
0:30:39 > 0:30:43These organisms were very simple animals.
0:30:43 > 0:30:49Beyond the reach of light, they had to survive by absorbing chemical sustenance.
0:30:49 > 0:30:54But most animals we know today are able to move about.
0:30:54 > 0:30:58Even sponges and corals have swimming larvae.
0:30:58 > 0:31:01But there's no evidence of that here.
0:31:03 > 0:31:06The creatures were all immobile.
0:31:06 > 0:31:08Nothing could move.
0:31:08 > 0:31:10Nothing had a mouth,
0:31:10 > 0:31:13nothing had muscles.
0:31:14 > 0:31:17Probably none of them had colour,
0:31:17 > 0:31:21probably an eerie whiteish colour to everything.
0:31:23 > 0:31:29These are the oldest large multi-cellular creatures on Earth,
0:31:29 > 0:31:32the oldest things that might be called proto-animals.
0:31:34 > 0:31:38This is not like anything that exists on earth today.
0:31:38 > 0:31:41Even though they're not directly related to us,
0:31:41 > 0:31:47like some distant relative, they provide us with a view of our own beginnings.
0:31:50 > 0:31:55One of the most peculiar things about these wonderful proto-animals
0:31:55 > 0:31:58is the way they constructed their bodies.
0:32:00 > 0:32:05Unlike modern creatures, they had a very simple pattern of branching.
0:32:10 > 0:32:14Despite their size, these are still very simple animals.
0:32:14 > 0:32:18They can be put together with just six to eight genetic commands,
0:32:18 > 0:32:25as against some 25,000 such commands that were needed to construct a mammal like me.
0:32:25 > 0:32:28You can see this if you look at them in detail.
0:32:28 > 0:32:31You see that they are made up of a series of very small modules
0:32:31 > 0:32:35which are attached to one another in a number of different ways.
0:32:37 > 0:32:43Their modular or fractal way of building their bodies is one of Guy Narbonne's main areas of research.
0:32:46 > 0:32:50His study is centred on one particular species.
0:32:51 > 0:32:53This is Fractofusus.
0:32:53 > 0:32:56It's the most common fossil in the Mistaken Point assemblage.
0:32:56 > 0:32:58We have literally thousands of specimens.
0:32:58 > 0:33:01And it would have lain on the sea bottom like you see there.
0:33:01 > 0:33:05A spindle-shaped mass, very thin.
0:33:05 > 0:33:08It consists of these elements.
0:33:08 > 0:33:10And there are 20 of them on either side.
0:33:10 > 0:33:13And if you look at an individual element,
0:33:13 > 0:33:15it's remarkably finely-branched.
0:33:15 > 0:33:18It's a style we called fractal or self-similar.
0:33:20 > 0:33:24These fractal organisms grew by repetitive branching,
0:33:24 > 0:33:27with each branch exactly the same as its predecessor
0:33:27 > 0:33:30from the microscopic level upwards.
0:33:32 > 0:33:37It was a simple, yet extremely, effective way of building a body.
0:33:44 > 0:33:50Such finely-divided branches gave the organism a huge surface area,
0:33:50 > 0:33:55and this allowed them to absorb nutrients directly without mouths and without guts.
0:33:58 > 0:34:02This simple fractal body plan proved very successful.
0:34:03 > 0:34:09So animals using it grew large for the first time in the history of life on Earth.
0:34:13 > 0:34:19Fractal design was perfect for getting these earliest creatures off and running
0:34:19 > 0:34:21and its easy to see why.
0:34:21 > 0:34:26It takes a minimum of genetic programming in order to make one.
0:34:26 > 0:34:29You could probably do it with six or eight codes in your PC
0:34:29 > 0:34:32to make something that was fractally branching.
0:34:32 > 0:34:37And then combining them to make up larger elements is literally child's play,
0:34:37 > 0:34:43like a toddler might take Lego blocks and put them all together in order to make up a larger structure.
0:34:47 > 0:34:54The fossils of Mistaken Point provide a detailed record of fractal animals.
0:34:54 > 0:35:00But the absence of anything like them in more recent rocks is very significant.
0:35:02 > 0:35:07Just a few million years after they first evolved, they vanished.
0:35:09 > 0:35:11They have no living descendents.
0:35:11 > 0:35:14They were an evolutionary dead end.
0:35:15 > 0:35:17And the reason?
0:35:17 > 0:35:21The very simplicity of their fractal way of growing.
0:35:22 > 0:35:30They utterly dominate about the first 20 million years of the evolution of complex multi-cellular proto-animals.
0:35:30 > 0:35:34However, this fast start was also their demise.
0:35:34 > 0:35:38Because they were incapable of evolving things like
0:35:38 > 0:35:43guts and brains and muscles and teeth that later animals did.
0:35:45 > 0:35:49If animals were to acquire these things,
0:35:49 > 0:35:53they would have to build their bodies in a completely different way.
0:35:53 > 0:35:58And eventually, animals appeared that did exactly that.
0:36:00 > 0:36:05To see them, I'm travelling south from Newfoundland across the equator
0:36:05 > 0:36:06to South Australia.
0:36:12 > 0:36:15The Ediacara Hills.
0:36:17 > 0:36:25Here lie animals whose body plans are fundamentally the same as those of almost all animals alive today...
0:36:25 > 0:36:27including us.
0:36:29 > 0:36:35The creatures that are preserved here lived just after fractal animals began to die out.
0:36:41 > 0:36:48And about 550 million years ago, their differently-organised bodies gave them something quite new...
0:36:52 > 0:36:53..mobility.
0:36:56 > 0:37:01But how and why did animals first begin to move?
0:37:01 > 0:37:06Scientists are beginning to find answers to those fascinating questions.
0:37:06 > 0:37:11And much of the detail comes from these extraordinary fossils behind me.
0:37:15 > 0:37:20A team of scientists, led by palaeontologist Dr Jim Gehling
0:37:20 > 0:37:23is uncovering the evidence in great detail.
0:37:25 > 0:37:27When you have these beds covered in red clay
0:37:27 > 0:37:31you have a good chance of the beds having well-preserved fossils.
0:37:31 > 0:37:34This is the original sea floor.
0:37:36 > 0:37:42And this sea-floor was very different from that in the deep waters of Mistaken Point.
0:37:42 > 0:37:44This was once a shallow reef.
0:37:44 > 0:37:47It is 550 million years old.
0:37:48 > 0:37:53The surface of the ocean floor was covered with organic ooze.
0:37:53 > 0:37:56It may have even been green or orange. We don't know the colour.
0:37:56 > 0:38:03But there was a lot of organic material made up by bacteria and all sorts of microorganisms.
0:38:03 > 0:38:10But sitting in and amongst that garden of slime, we would have seen these strange creatures.
0:38:13 > 0:38:16Jim Gehling's team is working to decipher the fossils.
0:38:16 > 0:38:21But it is not easy because these creatures still lacked any hard parts to their bodies.
0:38:25 > 0:38:29If I was working on dinosaurs, I'd go to a spot,
0:38:29 > 0:38:34find the bones and carefully dig them up, take them back into the lab, reconstruct the dinosaur.
0:38:34 > 0:38:40But I'm not dealing with bones. I'm dealing with soft-bodied creatures.
0:38:40 > 0:38:46All you've got are imprints of squishy things living flat on the seafloor.
0:38:47 > 0:38:52Despite the challenges, Jim has discovered compelling evidence here
0:38:52 > 0:38:55that these animals had begun to move.
0:38:58 > 0:39:02On this fossil bed, we find something very interesting.
0:39:02 > 0:39:06It's a series of faint, but very definite circles.
0:39:06 > 0:39:11They are almost identical in size and they overlap quite often.
0:39:11 > 0:39:15And then when you go to the end of the series of discs,
0:39:15 > 0:39:21you find a hollow with the imprint of a very distinct fossil,
0:39:21 > 0:39:23that of Dickinsonia.
0:39:25 > 0:39:28Dickinsonia was a cushion-like creature
0:39:28 > 0:39:31that lay flat on the seafloor.
0:39:31 > 0:39:36It ranged from the size of a penny to that of a bath mat.
0:39:39 > 0:39:43These imprints represent something very important.
0:39:43 > 0:39:45They are the first evidence
0:39:45 > 0:39:48of a kind of mobility of animals on the seafloor.
0:39:50 > 0:39:56The first animal movements were undoubtedly slow, but perhaps even too slow to notice.
0:39:56 > 0:40:00To see them in action, you have to speed them up.
0:40:04 > 0:40:08Dickinsonia crept from one feeding place to the next,
0:40:08 > 0:40:13absorbing the organic matter beneath it and then moving on once again.
0:40:13 > 0:40:19Perhaps it moved with the help of hundreds of tiny tubular feet, as starfish do today.
0:40:24 > 0:40:32The excavations at Ediacara reveal that Dickinsonia wasn't the only mobile creature around.
0:40:32 > 0:40:37Animals everywhere were on the move, actively seeking food.
0:40:37 > 0:40:45This shape here is a resting place of a slug-like animal called Kimberella.
0:40:45 > 0:40:50And these here, marks, are showing how it fed.
0:40:50 > 0:40:52It had a proboscis, a snout,
0:40:52 > 0:40:59and it fed by sifting through the mud, making these scratch marks.
0:40:59 > 0:41:03But it tells us more than how this animal fed.
0:41:03 > 0:41:07It also tells us how it moved because if you look back this way,
0:41:07 > 0:41:09this is where is started feeding
0:41:09 > 0:41:13and then it moved along here with more feeding marks and grooves,
0:41:13 > 0:41:16and then it settled down here
0:41:16 > 0:41:19into the mud where its final resting place was.
0:41:19 > 0:41:23So this shows that the animal not only fed like that,
0:41:23 > 0:41:25it actually moved like that.
0:41:27 > 0:41:32Kimberella was a very early ancestor of today's molluscs.
0:41:32 > 0:41:34It probably had a single muscular foot,
0:41:34 > 0:41:37just as snails and slugs have today
0:41:37 > 0:41:41with which it pulled itself along the sea bottom.
0:41:41 > 0:41:45Our speeded-up view of the Ediacaran seafloor
0:41:45 > 0:41:48gives an idea of what a busy place the oceans had now become.
0:42:01 > 0:42:05Whether that movement is by creeping or crawling over the seafloor,
0:42:05 > 0:42:07it doesn't matter because that animal
0:42:07 > 0:42:12has advantages over an animal that is fixed to the seafloor.
0:42:12 > 0:42:14It can move away from danger.
0:42:14 > 0:42:18It can move towards richer sources of food.
0:42:18 > 0:42:23It can move away from places which are over-colonised by its neighbours.
0:42:23 > 0:42:28That gives it an enormous advantage in the history of life.
0:42:38 > 0:42:45This new mobility was only made possible by a major change in the layout of animals' bodies.
0:42:46 > 0:42:51When we get to Ediacara, we still have some of those beautiful fractal-like forms
0:42:51 > 0:42:59that you see at Mistaken Point but in the Ediacara Hills we see something very different
0:42:59 > 0:43:01and that is, for the first time,
0:43:01 > 0:43:08you see a blueprint for all animals from then on, including ourselves.
0:43:09 > 0:43:15'The modern animal body plan is called bilateral symmetry.'
0:43:15 > 0:43:17What we see here is Spriggina.
0:43:21 > 0:43:23Let's make a cast of the fossil.
0:43:25 > 0:43:30Spriggina represents the first ever animal
0:43:30 > 0:43:33which had clear bilateral symmetry.
0:43:33 > 0:43:38It had a body with a head at one end, a tail at the other.
0:43:38 > 0:43:42And almost identical halves, if you split it down the middle.
0:43:45 > 0:43:48We see these together with other creatures
0:43:48 > 0:43:52which have this kind of body form.
0:43:52 > 0:43:56Spriggina is just one of countless kinds of fossils
0:43:56 > 0:44:00in the Ediacara Hills that had developed in this way.
0:44:01 > 0:44:07It had a head and a tail, and so it moved in a particular direction.
0:44:10 > 0:44:16It's quite likely that they had sensory organs concentrated in the head.
0:44:16 > 0:44:20Now why does my nose occur near my mouth?
0:44:20 > 0:44:24It's a very good reason. I want to smell the food before I ingest it.
0:44:24 > 0:44:27Why are my eyes above my mouth?
0:44:27 > 0:44:29So I can see what I'm eating.
0:44:29 > 0:44:36This head demonstrates that sensory capacity had evolved.
0:44:36 > 0:44:41It was able to sense where food was likely to be on the seafloor.
0:44:41 > 0:44:47And, therefore, clearly had a mechanism for actually moving towards that food.
0:44:49 > 0:44:54Bilateral animals like Spriggina had another advantage.
0:44:54 > 0:44:58Between the head and the tail, there are numerous segments.
0:45:00 > 0:45:06So these animals could increase in size by simply adding more segments.
0:45:06 > 0:45:11What is more, each segment could do a particular job.
0:45:11 > 0:45:13Once you start to move,
0:45:13 > 0:45:16you develop a front end and that becomes your head.
0:45:16 > 0:45:19And you also, by definition, have a back end.
0:45:19 > 0:45:23And in between, segments on which you can add appendages.
0:45:23 > 0:45:26On that basic pattern, you can add further features.
0:45:26 > 0:45:30On the front end, that's where you need sense organs, eyes, feelers.
0:45:30 > 0:45:34On the appendages, you can modify them to be hooks and claws
0:45:34 > 0:45:36that would help you to catch things.
0:45:36 > 0:45:42And at the back end, there will be a pore from which you excrete the waste products.
0:45:42 > 0:45:48And that is the basic body plan of almost all the animals that are alive on Earth today.
0:45:50 > 0:45:57It had taken 3,000 million years for multi-celled organisms to appear for the first time.
0:45:57 > 0:46:03But now, less than 100 million years later, an evolutionary blink of an eye,
0:46:03 > 0:46:09animals had appeared that had the same basic body plan as most that live today.
0:46:09 > 0:46:13They had heads and tails and segmented bodies.
0:46:13 > 0:46:16And they were able to move to find food.
0:46:17 > 0:46:21How was it that animals had suddenly become so complex?
0:46:24 > 0:46:29The Ediacara Hills may hold the evidence for an answer to that question.
0:46:34 > 0:46:38Living organisms don't live forever.
0:46:38 > 0:46:46If a species is to survive it has to reproduce and the first simple animals did that very simply,
0:46:46 > 0:46:48by straightforwardly dividing.
0:46:48 > 0:46:56But if a species is to survive it also has to have the ability to change with a changing environment.
0:46:56 > 0:47:01And to do that involves reproducing in a rather different way.
0:47:01 > 0:47:09Evidence of how that happened can also be seen is these very ancient Australian rocks.
0:47:20 > 0:47:25In 2007, palaeontologist Dr Mary Droser
0:47:25 > 0:47:30discovered in these 550-million-year-old deposits
0:47:30 > 0:47:34evidence that animals had started to reproduce sexually.
0:47:36 > 0:47:41The animal concerned is called Funisia.
0:47:44 > 0:47:48If Droser's theory is right, this wormlike creature produced offspring
0:47:48 > 0:47:53by exchanging genetic material with other individuals.
0:47:53 > 0:47:56This gene-swapping, or sex,
0:47:56 > 0:48:02shuffles the genetic pack, greatly accelerating variation and therefore evolution.
0:48:07 > 0:48:10Sexual reproduction is absolutely one of the most fundamental steps
0:48:10 > 0:48:12in the history of life.
0:48:12 > 0:48:14It is why we have the diversity that we have.
0:48:14 > 0:48:16It's the birds and the bees.
0:48:16 > 0:48:20As far as we know, this is the first evidence of animals' sexual reproduction,
0:48:20 > 0:48:24and we're not catching the animal in the act of it,
0:48:24 > 0:48:29we're looking at the product of what we conclude was sexual reproduction.
0:48:29 > 0:48:33This fossil is key to Mary Droser's argument.
0:48:33 > 0:48:37The small circles show where the animals were anchored to the ground.
0:48:38 > 0:48:43You can see that these attachment structures are basically all the same size.
0:48:43 > 0:48:46They're all about a couple of millimetres in diameter.
0:48:46 > 0:48:51And you could go to another bed, and all the Funisia are half a centimetre in diameter.
0:48:51 > 0:48:54So the same size are all occurring together.
0:48:54 > 0:48:59This uniformity of size in a particular place is, Mary Droser believes,
0:48:59 > 0:49:04strong evidence that a new way of reproducing had arrived.
0:49:04 > 0:49:06We link this to sexual reproduction
0:49:06 > 0:49:11because if you look in modern environments, when you have this kind of size groupings,
0:49:11 > 0:49:16that is 99.9% of the time a product of sexual reproduction.
0:49:18 > 0:49:25To understand why, I'm travelling 2,000 miles northeast of Ediacara to the Great Barrier Reef.
0:49:29 > 0:49:35Here, there are modern creatures that reproduce in the way that Funisia is thought to have done.
0:49:35 > 0:49:38They're corals.
0:49:46 > 0:49:51Corals, like Funisia, are anchored to the seabed.
0:49:51 > 0:49:56They feed by filtering food from the water.
0:49:58 > 0:50:04And the way they breed creates one of nature's greatest annual spectacles.
0:50:06 > 0:50:11Once a year, there's an important event among the corals.
0:50:11 > 0:50:13We're not sure how it's coordinated.
0:50:13 > 0:50:16It probably has something to do with the moon.
0:50:16 > 0:50:22But it gives us a hint as to how sexual reproduction might have first appeared.
0:50:30 > 0:50:33At exactly the same time,
0:50:33 > 0:50:38the corals release countless millions of sperm and eggs all at once.
0:50:48 > 0:50:52The event is precisely timed to maximise the chances
0:50:52 > 0:50:54of fertilisation.
0:50:56 > 0:50:59Millions of offspring are simultaneously conceived.
0:51:05 > 0:51:09So, as the coral grows, the individuals that make up
0:51:09 > 0:51:15the colonies are all of exactly the same age and size,
0:51:15 > 0:51:17just like Funisia.
0:51:22 > 0:51:26It's unlikely that Funisia was the first animal to reproduce sexually.
0:51:26 > 0:51:33But its discovery suggests that many other animals are also reproducing by mixing their genes.
0:51:33 > 0:51:39And that might explain how complex animals evolved so quickly.
0:51:44 > 0:51:48The arrival of sexual reproduction speeded evolution.
0:51:48 > 0:51:53Here was a mechanism that produced greater genetic variation more quickly.
0:51:53 > 0:51:59So, over many generations, species were able to adapt to their changing environments.
0:52:01 > 0:52:07550 million years ago, animal life was on the verge of a major advance.
0:52:09 > 0:52:15In an environment where animals were becoming more mobile, they would have to adapt fast.
0:52:15 > 0:52:19Movement requires a lot of energy.
0:52:19 > 0:52:22Simply absorbing nutrients through the surface of the body
0:52:22 > 0:52:26as Dickinsonia did was much too slow a process.
0:52:28 > 0:52:32Mobile animals would need to consume huge quantities of food.
0:52:32 > 0:52:37And they would do that by evolving the very first stomachs, mouths and teeth.
0:52:39 > 0:52:44You can see how they might have done so in Switzerland...
0:52:48 > 0:52:53..where a new kind of technology provides a window into the past.
0:53:00 > 0:53:06This stadium-sized building houses one of the world's most powerful microscopes.
0:53:11 > 0:53:14It's called the synchrotron.
0:53:19 > 0:53:25Professor Philip Donoghue is preparing the tiniest of fossils for the synchrotron.
0:53:27 > 0:53:33These miniscule balls were excavated from a quarry in South China.
0:53:33 > 0:53:38Each and every one of them is the fossilised embryo of an ancient creature.
0:53:42 > 0:53:45If we really want to understand these fossils,
0:53:45 > 0:53:48what we need to do is not just to look at the surface
0:53:48 > 0:53:50which we can do with an electron microscope.
0:53:50 > 0:53:51We need to look inside.
0:53:51 > 0:53:56We have to use some form of X-ray tomography, a bit like CAT scanners in hospitals.
0:53:56 > 0:54:03But we have to use one that allows us to look at the very tiniest details down to a thousandth of a millimetre.
0:54:03 > 0:54:06The synchrotron is the only X-ray type machine that provides
0:54:06 > 0:54:11the kinds of resolution that we need to see all the tiny details within the fossilised embryos.
0:54:13 > 0:54:15KLAXON SOUNDS
0:54:17 > 0:54:21It was astonishing, I mean it was a real eureka moment
0:54:21 > 0:54:26that you could get to the very finest levels of fossilisation,
0:54:26 > 0:54:30the very finest detail that the fossil record could ever give up using this technology.
0:54:38 > 0:54:46Powerful generators fire high-energy electrons around a circular tube at close to the speed of light.
0:54:50 > 0:54:58After one million orbits, the electrons emit X-rays so powerful, they can penetrate solid rock
0:54:58 > 0:55:00or these tiny fossils.
0:55:02 > 0:55:05Donoghue uses data from the synchrotron
0:55:05 > 0:55:08to build a three-dimensional picture of the fossils.
0:55:10 > 0:55:15We know it's a fossil embryo because it's surrounded by a preserved egg sac.
0:55:15 > 0:55:20And using tomography we can see inside to the developing animal.
0:55:25 > 0:55:30This fossil is the embryo of a tiny marine worm called Markuelia.
0:55:32 > 0:55:36It lived just twenty million years after the animals of Ediacara.
0:55:43 > 0:55:48Using his 3D model, Donoghue is able to see inside it
0:55:48 > 0:55:51and there he found evidence of something new.
0:55:53 > 0:55:58These fossils provide the first clear evidence for a gut within animals.
0:55:58 > 0:56:03We can clearly see that there's a mouth right at one end
0:56:03 > 0:56:06surrounded by rings of teeth that extend inside the mouth.
0:56:06 > 0:56:10And then there's a gut that extends all the way through to an anus at the other end.
0:56:12 > 0:56:20Internal digestion enabled Markuelia to extract energy from its food in a very efficient way.
0:56:23 > 0:56:29And the fact that it had teeth suggests that it had a new diet -
0:56:29 > 0:56:30other animals.
0:56:33 > 0:56:38The fact that it's got rings of teeth arranged by its mouth, that it would have averted out
0:56:38 > 0:56:43or it would have ejected out of its mouth to grasp prey items, tells us that this thing was a predator.
0:56:47 > 0:56:50For the first time, there were hunters in the oceans.
0:56:50 > 0:56:55And that had enormous evolutionary implications.
0:57:04 > 0:57:11There was about to be an explosion of life that would lay the foundations for modern animals.
0:57:16 > 0:57:19In another wave of evolution,
0:57:19 > 0:57:23the animal basic body plan became more and more elaborate.
0:57:23 > 0:57:27Fearsome predators appeared in the seas,
0:57:27 > 0:57:33great monsters on the land and animals became masters of the Earth.
0:57:36 > 0:57:42Next time I continue my journey in the Rocky Mountains of Canada,
0:57:42 > 0:57:45the deserts of North Africa
0:57:45 > 0:57:49and the tropical rainforests of Australia.
0:57:49 > 0:57:56I will discover how and why animals evolved skeletons and shells.
0:57:56 > 0:57:59How they developed true, picture-forming eyes.
0:58:01 > 0:58:04How others went to extraordinary lengths
0:58:04 > 0:58:08to protect themselves from attack.
0:58:08 > 0:58:14And I shall discover the first animals that moved out of the sea to conquer the land and the air.
0:58:36 > 0:58:39Subtitles by Red Bee Media Ltd
0:58:39 > 0:58:42E-mail subtitling@bbc.co.uk