0:00:03 > 0:00:07What does it take to be a scientific pioneer?
0:00:10 > 0:00:13To reframe and popularise evolutionary theory?
0:00:16 > 0:00:20To reveal a new material, and win science's most coveted prize?
0:00:22 > 0:00:26To discover one of palaeontology's elusive missing links?
0:00:29 > 0:00:35Is the key to brilliance talent, ego or just plain good luck?
0:00:35 > 0:00:39What makes a beautiful scientific mind?
0:00:39 > 0:00:42Professor Jenny Clack is a world-renowned palaeontologist,
0:00:42 > 0:00:48who solved one of the greatest riddles in the history of life on our planet.
0:00:48 > 0:00:52One of the big questions that people had been trying to answer was,
0:00:52 > 0:00:57how do you get from an animal that lives in the water and has fins,
0:00:57 > 0:01:01to an animal that walks on land and has limbs with fingers and toes?
0:01:04 > 0:01:09In the late 1980s, she found and described the fossil Acanthostega,
0:01:09 > 0:01:11an ancient creature which offered new evidence
0:01:11 > 0:01:16of how fish evolved legs and made the transition onto land.
0:01:17 > 0:01:21Her talent for seeing what others had missed rewrote the textbooks
0:01:21 > 0:01:24and led to global recognition for her work.
0:01:26 > 0:01:27She's the great pioneer.
0:01:27 > 0:01:30She's the one who led the way
0:01:30 > 0:01:34and opened up this area that we others have come into.
0:01:34 > 0:01:36We do talk about the Clack theory of the origin of tetrapods.
0:01:36 > 0:01:41It does sometimes do to think about things that you take for granted.
0:01:41 > 0:01:45What if it's not this way, but it's the other way?
0:01:45 > 0:01:50But becoming a pioneer was by no means inevitable.
0:01:50 > 0:01:53She's not a person with sharp elbows. That's not it at all.
0:01:53 > 0:01:58It was quite clear she didn't have a great deal of confidence in herself.
0:01:59 > 0:02:02Clack had to find the courage to take on
0:02:02 > 0:02:07the stifling academic etiquette that had hampered research for decades.
0:02:07 > 0:02:12The field had become moribund, and now it's been completely unlocked.
0:02:12 > 0:02:17Answering one of evolution's greatest mysteries would mean
0:02:17 > 0:02:19travelling to almost the ends of the earth for fossil evidence.
0:02:20 > 0:02:24I was actually terrified, but discovery of those materials
0:02:24 > 0:02:28was probably the most exciting thing after falling in love.
0:02:30 > 0:02:33Just what does it take to turn accepted thinking on its head,
0:02:33 > 0:02:36and make the palaeontological discovery of a generation?
0:02:49 > 0:02:54Jenny Clack has made a life's work out of trying to find traces of a world
0:02:54 > 0:02:58hundreds of millions of years ago, before even the dinosaurs.
0:03:01 > 0:03:05Her passion is for the very first creatures that emerged from the seas
0:03:05 > 0:03:06to conquer the Earth.
0:03:08 > 0:03:12For me, trying to imagine what these animals were like,
0:03:12 > 0:03:16it's a sense of mystery, where the animals are totally different
0:03:16 > 0:03:17from anything that we have today.
0:03:17 > 0:03:19It's trying to just imagine what they were like and what they were
0:03:20 > 0:03:26doing, and what life was like for them, and just wanting to be there.
0:03:28 > 0:03:30But the evidence is elusive.
0:03:31 > 0:03:33With only scant fossilised remains to go on,
0:03:33 > 0:03:37seeing into the rocks poses a creative challenge.
0:03:38 > 0:03:42That has a lot to do with wanting to see something else
0:03:42 > 0:03:45in the specimen that nobody's ever seen before,
0:03:45 > 0:03:48and being able to see a little bit more about it.
0:03:48 > 0:03:51It all goes into this sort of imagination
0:03:51 > 0:03:53of what the animal would have been like.
0:03:58 > 0:04:02Jenny's fascination for this era, known as the Devonian,
0:04:02 > 0:04:05has fuelled her imagination since early childhood.
0:04:09 > 0:04:13What sparked my interest in palaeontology
0:04:13 > 0:04:16was an illustrated book called Prehistoric Animals,
0:04:16 > 0:04:20and it had sections on the earliest part of the fossil record,
0:04:20 > 0:04:25and it was always those earlier sections that really intrigued me,
0:04:25 > 0:04:30and I remember flicking through this book, starting at the beginning,
0:04:30 > 0:04:37and listening to the slow movement of Shostakovich's Fifth Symphony,
0:04:37 > 0:04:43and if you do that, the music fits the pictures perfectly.
0:04:43 > 0:04:46And if you know that piece of music,
0:04:46 > 0:04:50that kind of sums up how I imagine the Devonian to be.
0:04:54 > 0:04:57The story of the colonisation of the land by the creatures that
0:04:57 > 0:05:00emerged from the swamps and pools of the Devonian Period
0:05:00 > 0:05:05is one of the most fascinating episodes in the history of life.
0:05:05 > 0:05:09But this mysterious world was a long way from the Manchester suburb
0:05:09 > 0:05:10where Jenny grew up.
0:05:17 > 0:05:20It wasn't a particularly special household.
0:05:20 > 0:05:23A simple terraced house, fronting onto a road.
0:05:23 > 0:05:25My parents were not at all academic.
0:05:25 > 0:05:28In fact, they were very poorly educated,
0:05:28 > 0:05:30and I don't remember the house being full of books, for example,
0:05:30 > 0:05:33apart from the ones I borrowed from the library.
0:05:33 > 0:05:36But we had the great advantage that,
0:05:36 > 0:05:40across the road from where I lived, was a pond,
0:05:40 > 0:05:44and in that pond were sticklebacks and tadpoles and all sorts
0:05:44 > 0:05:50of wonderful things, and I used to bring home sticklebacks and newts.
0:05:50 > 0:05:53My mother hated newts, but she let me keep them anyway.
0:05:53 > 0:05:55And that was just a wonderful resource.
0:05:55 > 0:06:00I was an only child, so I would go there regularly by myself.
0:06:00 > 0:06:04Intrigued by the primitive-looking animals she found on her doorstep,
0:06:04 > 0:06:07Jenny soon discovered there was another way
0:06:07 > 0:06:10she could connect with creatures from the distant past.
0:06:11 > 0:06:12Through fossils.
0:06:15 > 0:06:18The remains of these animals will be down in the rocks,
0:06:18 > 0:06:19well below the surface of the Earth,
0:06:19 > 0:06:22but where cliffs like this have broken away,
0:06:22 > 0:06:28then the rocks are exposed, and we can see where the animals' remains are.
0:06:28 > 0:06:31By the time I was 11 or 12,
0:06:31 > 0:06:35I'd heard of this great Victorian fossil hunter called Mary Anning,
0:06:35 > 0:06:37who lived and worked at Lyme Regis,
0:06:37 > 0:06:41and found some wonderful specimens like the fish lizards,
0:06:41 > 0:06:46ichthyosaurs, and I decided that I wanted to be the new Mary Anning.
0:06:46 > 0:06:49So we duly went to Lyme Regis.
0:06:59 > 0:07:02While most children were playing on the beach,
0:07:02 > 0:07:05Jenny was engrossed by the fossils.
0:07:05 > 0:07:09I didn't find any ichthyosaurs, but we did find lots of ammonites,
0:07:09 > 0:07:12and I thought to myself, "Wow, that sounds wonderful.
0:07:12 > 0:07:13"I really want to do that."
0:07:16 > 0:07:19Jenny had found her life's passion,
0:07:19 > 0:07:21but for a girl growing up in the 1950s,
0:07:21 > 0:07:25palaeontology wasn't seen as an obvious choice.
0:07:25 > 0:07:29'Science plays an important part in the curriculum, these days.
0:07:29 > 0:07:33'But girls who may be among the leading biologists must also
0:07:33 > 0:07:37'be able to use their hands, and that's a useful experience
0:07:37 > 0:07:41'when it comes to shopping in the future.'
0:07:41 > 0:07:43When I was in my secondary school,
0:07:43 > 0:07:47I actually felt very much of an also-ran.
0:07:47 > 0:07:49I don't think I was considered anything special.
0:07:49 > 0:07:54Certainly, it was never suggested that I would take the Oxbridge exams.
0:07:54 > 0:07:58When it came to A-levels, they weren't as good as expected,
0:07:58 > 0:08:03and I actually got into my fourth choice, Newcastle upon Tyne,
0:08:03 > 0:08:09chosen really on the list at all because, one, it had a palaeontology option,
0:08:09 > 0:08:13and two, it had a Gilbert and Sullivan society.
0:08:14 > 0:08:15Don't let's be downhearted!
0:08:15 > 0:08:19There's a silver lining to every cloud.
0:08:19 > 0:08:22Certainly! Let's be perfectly happy!
0:08:22 > 0:08:25By all means! Let's thoroughly enjoy ourselves!
0:08:25 > 0:08:27It's absurd to cry.
0:08:27 > 0:08:28Quite ridiculous!
0:08:28 > 0:08:30Jenny's fourth choice turned out to be a lucky one.
0:08:30 > 0:08:34The palaeontology option was thriving at Newcastle,
0:08:34 > 0:08:37under the leadership of the forward-thinking Dr Alec Panchen.
0:08:38 > 0:08:40'At Newcastle University Department of Zoology,
0:08:40 > 0:08:44'Dr Alec Panchen talks about the difficulty of deciding
0:08:44 > 0:08:49'how the first reptiles may have emerged from amphibian ancestors.'
0:08:49 > 0:08:54If one looks at a reptile, such as a lizard,
0:08:54 > 0:08:58and then an amphibian, such as a newt or a salamander,
0:08:58 > 0:09:02the differences between the two aren't so obvious.
0:09:02 > 0:09:06Dr Panchen's lab was one of the few places in the world
0:09:06 > 0:09:09looking at the origin of tetrapods,
0:09:09 > 0:09:13the broad term used for all four-limbed vertebrates,
0:09:13 > 0:09:15from amphibians to mammals.
0:09:17 > 0:09:20He was studying the earliest known tetrapods,
0:09:20 > 0:09:23from over 300 million years ago,
0:09:23 > 0:09:28precisely the era that had fired Jenny's childhood imagination.
0:09:28 > 0:09:30But Dr Panchen set a high bar.
0:09:32 > 0:09:35Alec Panchen was a very meticulous worker.
0:09:37 > 0:09:38His papers have immense detail.
0:09:38 > 0:09:42His drawings, beautiful reconstructions of skulls,
0:09:42 > 0:09:44incredibly detailed.
0:09:44 > 0:09:46Quite intimidatingly, for his students.
0:09:46 > 0:09:49We all felt we had to try and draw like that
0:09:49 > 0:09:53or we would be failures, and it certainly pulled us up a lot.
0:09:53 > 0:09:55Although keen to study with Panchen,
0:09:55 > 0:09:58Jenny found it hard to attract his attention.
0:09:58 > 0:10:02I actually found him quite difficult to talk to.
0:10:02 > 0:10:05He's very, very reserved.
0:10:05 > 0:10:11When you get two people who are quite reserved together,
0:10:11 > 0:10:14the conversation doesn't always flow freely, shall we say.
0:10:14 > 0:10:20Panchen's elite group of PhD students seemed out of reach.
0:10:20 > 0:10:23Well, she was very reserved, and in that sense,
0:10:23 > 0:10:26maybe she didn't feel confident enough,
0:10:26 > 0:10:29but there was no indication that she had talents
0:10:29 > 0:10:32that would get her where it finally did.
0:10:32 > 0:10:37When I got to my final year, I would have liked to do a PhD
0:10:37 > 0:10:39in palaeontology,
0:10:39 > 0:10:43but I was also told that Panchen didn't take anybody on
0:10:43 > 0:10:45who hadn't got a first,
0:10:45 > 0:10:48and I thought I was unlikely to get a first.
0:10:48 > 0:10:50And, in fact, I didn't.
0:10:50 > 0:10:52And so, I sort of gave up on that idea.
0:10:54 > 0:10:59Instead of applying to join Dr Panchen's exclusive circle
0:10:59 > 0:11:02of research graduates, Jenny opted for a less challenging job
0:11:02 > 0:11:05in a regional museum in Birmingham.
0:11:07 > 0:11:10My first job was a display technician.
0:11:10 > 0:11:14Well, I wasn't altogether happy as a museum education person,
0:11:14 > 0:11:16because I'm not that comfortable with children,
0:11:16 > 0:11:19and of course a lot of the job was working with children.
0:11:19 > 0:11:21I don't really know how to deal with them.
0:11:21 > 0:11:25And she might have stayed in that job without the encouragement
0:11:25 > 0:11:28that came from a chance meeting.
0:11:31 > 0:11:34When I was working in Birmingham, I got interested in motorcycles.
0:11:36 > 0:11:40And while I was at motorcycle club, I was part of a folk group,
0:11:40 > 0:11:47and this guy was doing a floor spot, singing by himself with a guitar,
0:11:47 > 0:11:49and I don't know what brought this subject up,
0:11:49 > 0:11:55I don't know why he mentioned it, but he said the word dimetrodon.
0:11:59 > 0:12:04She heard the magic word and pricked up her ears, and it really
0:12:04 > 0:12:08was just a matter of time before we actually met from then on.
0:12:08 > 0:12:11"What is this guy doing mentioning dimetrodon?"
0:12:11 > 0:12:14Pretty soon we got to know each other.
0:12:14 > 0:12:18So, yes, we never looked back.
0:12:20 > 0:12:24Jenny's future husband Rob didn't only share her passion for bikes.
0:12:24 > 0:12:29Soon the couple were hitting the road as fossil hunters.
0:12:33 > 0:12:37We certainly would take our holidays on the back of a bike,
0:12:37 > 0:12:41going up to Scotland to look for fossils.
0:12:43 > 0:12:45And Rob would prove to be a vital support
0:12:45 > 0:12:49at times when Jenny was uncertain how to progress.
0:12:49 > 0:12:56It was quite clear, in those days, that she didn't have a great deal of confidence in herself.
0:12:56 > 0:13:00But, looking back on it, that was simply a lack of experience.
0:13:00 > 0:13:05With Rob's encouragement, Jenny kept nurturing her passion for fossils,
0:13:05 > 0:13:09and it wasn't long before she spotted an opportunity.
0:13:09 > 0:13:14My boss at the time knew that I wasn't entirely content in that job,
0:13:14 > 0:13:19so she suggested that I do some private study,
0:13:19 > 0:13:24because the local authority actually allowed staff to take off
0:13:24 > 0:13:27three weeks a year to do some private study,
0:13:27 > 0:13:29and so I took a chance.
0:13:31 > 0:13:34Jenny knew that Bradford City Museum owned a fossil
0:13:34 > 0:13:38that had been discovered in a local coal mine.
0:13:39 > 0:13:44It was of a 300 million-year-old creature called Pholiderpeton,
0:13:44 > 0:13:47thought to be one of the first tetrapods to venture onto land.
0:13:48 > 0:13:54Jenny's old university tutor, Alec Panchen, had tried without success to get his hands on it.
0:13:54 > 0:13:56Many years before, they had put it on display
0:13:56 > 0:13:59embedded in a block of concrete,
0:13:59 > 0:14:02and they would never take it out of the concrete for Alec,
0:14:02 > 0:14:05and he was always very upset that this was the one specimen
0:14:05 > 0:14:07he had never been allowed to work on.
0:14:12 > 0:14:15Jenny hatched an idea that she thought just might impress him.
0:14:16 > 0:14:23Using her museum connections, she promptly went and borrowed it, so she had it.
0:14:23 > 0:14:27She recognised the power of having a good hand of cards
0:14:27 > 0:14:29when you negotiate something.
0:14:29 > 0:14:33Her hunch proved right.
0:14:33 > 0:14:38Intrigued, Dr Panchen invited her to join him in Newcastle to inspect the specimen.
0:14:39 > 0:14:42But it wasn't an easy fossil to get to grips with.
0:14:43 > 0:14:46I remember a colleague of mine having a look at the specimen,
0:14:46 > 0:14:49and he's used to dealing with roadkills, but he said,
0:14:49 > 0:14:50"My Goodness, that's a mess!"
0:14:50 > 0:14:54That was his reaction to the specimen.
0:14:56 > 0:14:59But it turned out to be much more interesting
0:14:59 > 0:15:01than you might have expected.
0:15:02 > 0:15:06Despite having little time to impress her old tutor,
0:15:06 > 0:15:09Jenny's sharp eye began to reveal itself.
0:15:10 > 0:15:16I was preparing it, and looking at the bits that hadn't been exposed to the surface before,
0:15:16 > 0:15:19and I found this peculiar chunky bone,
0:15:19 > 0:15:23and I showed this to Alec, and I remember his precise words.
0:15:23 > 0:15:26He said, "Well, I'm damned. It's a braincase."
0:15:27 > 0:15:31And then, a few seconds later, "There could be a PhD in this.
0:15:32 > 0:15:35"I could probably get a grant for you, if you're interested."
0:15:37 > 0:15:38Can a duck swim?
0:15:41 > 0:15:44Jenny promptly quit her museum job
0:15:44 > 0:15:47and headed to Newcastle to begin a new life of academic research.
0:15:50 > 0:15:56The Bradford fossil Pholiderpeton would form the basis of years of painstaking examination.
0:16:00 > 0:16:03'Here in the Department of Zoology at Newcastle University in England,
0:16:03 > 0:16:08'a research student is working on the fossil remains of one early amphibian.'
0:16:08 > 0:16:13This animal lived 300 million years ago, and one can only be
0:16:13 > 0:16:16fascinated and curious about what life was like in those days.
0:16:18 > 0:16:23I'm, in fact, the first person to restudy this animal since 1926.
0:16:24 > 0:16:27'She first of all cleans away parts of the matrix surrounding
0:16:27 > 0:16:31'the fossil using a dental mallet, then further cleaning up
0:16:31 > 0:16:35'by blasting with a jet of sodium bicarbonate particles.'
0:16:36 > 0:16:40You're exposing things that have never been seen by anybody before.
0:16:40 > 0:16:44It's compulsive. Your sense of time just disappears.
0:16:46 > 0:16:49And unless somebody comes and knocks on the door and says,
0:16:49 > 0:16:51"Time for a cup of tea," you could just stay there.
0:16:55 > 0:16:58When you go to sleep at night, and you close your eyes,
0:16:58 > 0:16:59you can see it in front of you.
0:17:01 > 0:17:02It's a bit like watching a movie.
0:17:05 > 0:17:07If you prepare your own material,
0:17:07 > 0:17:11it does give you an intimate view of what you've got.
0:17:11 > 0:17:16And this Bradford fossil was a rather strange specimen.
0:17:16 > 0:17:19It had, probably underwater,
0:17:19 > 0:17:24crawled inside a hollow tree trunk and died,
0:17:24 > 0:17:28and then decomposed, and you knew it was all one animal,
0:17:28 > 0:17:31and you knew that you had all the bits.
0:17:31 > 0:17:35If only you could take it apart and put them together the right way.
0:17:35 > 0:17:39As she put the pieces together, Jenny made a startling discovery.
0:17:43 > 0:17:45It was one Friday evening.
0:17:45 > 0:17:46I was working on the airbrasive,
0:17:46 > 0:17:51and there was a little bone right at the tip of the specimen,
0:17:51 > 0:17:57rather apart from all the other bones, so I sat and I prepared it.
0:17:57 > 0:17:59So, this thing is about yay long.
0:18:03 > 0:18:05Like nothing I'd ever seen before.
0:18:06 > 0:18:08And I thought, "Now, wait a minute.
0:18:08 > 0:18:12"The only bones that I can think of which have got holes
0:18:12 > 0:18:16"through like that that aren't vertebrae
0:18:16 > 0:18:21"would be one of the braincase bones at the back called the exoccipital,
0:18:21 > 0:18:24"or a stapes."
0:18:25 > 0:18:30My mind actually couldn't believe it to start with.
0:18:30 > 0:18:34The stapes is a tiny bone in the ear of modern vertebrates.
0:18:34 > 0:18:37Its ability to vibrate is critical to hearing.
0:18:38 > 0:18:41No-one had ever discovered a stapes in an early tetrapod before,
0:18:41 > 0:18:46as the bone was thought to be too small to survive fossilisation.
0:18:46 > 0:18:49But there was something strange about this stapes.
0:18:50 > 0:18:53What the stapes showed that I found
0:18:53 > 0:18:56was that it was completely the wrong shape,
0:18:56 > 0:19:02and it was fixed in a way that meant it couldn't transmit vibrations.
0:19:02 > 0:19:04It wasn't free to vibrate.
0:19:05 > 0:19:08So something odd was going on.
0:19:08 > 0:19:11A stapes that was too big and solid to vibrate
0:19:11 > 0:19:14would be useless for hearing in air.
0:19:14 > 0:19:16But the prevailing theory
0:19:16 > 0:19:19was that early land-dwelling tetrapods must be able to hear.
0:19:20 > 0:19:23Jenny wondered if there was another way of looking at it.
0:19:25 > 0:19:30It does sometimes do to think about things that you take for granted
0:19:30 > 0:19:31and turn them on their heads.
0:19:33 > 0:19:37What if it's not this way, but it's the other way?
0:19:37 > 0:19:42The assumption had been that as fish evolved into tetrapods,
0:19:42 > 0:19:44a bone in the jaw had rapidly transformed
0:19:44 > 0:19:47into the tiny stapes that could vibrate.
0:19:49 > 0:19:52Jenny's discovery suggested that this transformation had not
0:19:52 > 0:19:56occurred as early as previously thought.
0:19:56 > 0:20:01So, the stapes that I found is a step along the way into making
0:20:01 > 0:20:05a modern ear in something like modern reptiles.
0:20:05 > 0:20:08But it doesn't do it straight away.
0:20:09 > 0:20:12Jenny wondered whether the bone she'd identified was in fact
0:20:12 > 0:20:18evidence of a whole sense, hearing, in the process of evolving.
0:20:18 > 0:20:20What if these animals couldn't yet hear?
0:20:23 > 0:20:24Think about it like this.
0:20:25 > 0:20:28What was there for it to listen to?
0:20:28 > 0:20:35There weren't any creaking insects, there weren't any birds,
0:20:35 > 0:20:37no animals were making noises.
0:20:37 > 0:20:40The only sounds would have been the wind in the trees,
0:20:40 > 0:20:43leaves blowing about, that kind of thing.
0:20:43 > 0:20:47She began to trawl through decades of academic descriptions
0:20:47 > 0:20:51of the ears of early tetrapods,
0:20:51 > 0:20:53and soon realised that many of them did have stapes.
0:20:53 > 0:20:56Jenny had spotted something that had been right under peoples' noses
0:20:56 > 0:21:01all along, but simply dismissed as an unimportant scrap of bone.
0:21:01 > 0:21:08Alec Panchen had been working on another related animal for some time.
0:21:08 > 0:21:10There was a stapes, only Alec hadn't described it,
0:21:10 > 0:21:15and Jenny pointed it out to him, you know, there, and it looks the same,
0:21:15 > 0:21:20and he admitted that he had passed over it in embarrassed silence.
0:21:24 > 0:21:28Jenny's work on stapes updated the textbooks.
0:21:28 > 0:21:31Her unique way of seeing was yielding results.
0:21:31 > 0:21:36One of the interesting things about it is to show
0:21:36 > 0:21:40how what you see is governed by what you expect to see.
0:21:41 > 0:21:44And that happens all the time, actually.
0:21:44 > 0:21:48You don't always see what's there, because you've got a certain predisposition.
0:21:48 > 0:21:53It certainly had been excellent training for her,
0:21:53 > 0:21:57and it was clear that this was somebody who was capable of
0:21:57 > 0:22:00changing the way we thought about some of these animals.
0:22:00 > 0:22:03Well, it was at that point that I thought perhaps there were
0:22:03 > 0:22:06other things that people have always taken for granted
0:22:06 > 0:22:08that aren't the way we thought they were, and yes,
0:22:08 > 0:22:12that was a lesson that I've continued to apply.
0:22:14 > 0:22:17That certainly stood me in good stead.
0:22:20 > 0:22:22Jenny was beginning to get noticed.
0:22:23 > 0:22:25She landed a prestigious job
0:22:25 > 0:22:29as a curator at Cambridge University's Museum of Zoology.
0:22:32 > 0:22:36I was quite amazed when I got a job in Cambridge because,
0:22:36 > 0:22:40not having been considered as a candidate for Oxbridge at school,
0:22:40 > 0:22:43there's no way I was going to get into Cambridge.
0:22:43 > 0:22:48I sort of felt that I'd got in by the back door,
0:22:48 > 0:22:51via the museum connection.
0:22:51 > 0:22:55In those days, many of the staff at Cambridge
0:22:55 > 0:23:01still looked down on anyone who was "redbrick", and I think Jenny
0:23:01 > 0:23:05had a lot more problems from being a redbrick than being a woman.
0:23:06 > 0:23:10And certainly, several of them would always refer to her as Mrs Clack, not Dr Clack.
0:23:11 > 0:23:15Aware that critical eyes were upon her,
0:23:15 > 0:23:17and with the freedom now to pursue her own research,
0:23:17 > 0:23:20Jenny chose to tackle one of the biggest mysteries
0:23:20 > 0:23:22in our evolutionary story.
0:23:24 > 0:23:28One that had taxed some of the greatest minds in palaeontology
0:23:28 > 0:23:30for decades.
0:23:32 > 0:23:35One of the big questions that people had been trying to answer,
0:23:35 > 0:23:38in various ways,
0:23:38 > 0:23:44was how do you get from an animal that lives in the water and has fins,
0:23:44 > 0:23:48to an animal that walks on land and has limbs with fingers and toes?
0:23:49 > 0:23:54And the evidence was simply absent.
0:23:54 > 0:23:56Many of us would say it's more radical than anything that's
0:23:56 > 0:24:01taken place on land, and that the origin of reptiles,
0:24:01 > 0:24:05the origin of birds, the origin of mammals are all, really,
0:24:05 > 0:24:08less radical than this fish-to-tetrapod transition.
0:24:12 > 0:24:15It was thought that this important transition
0:24:15 > 0:24:21from fish to vertebrates with limbs occurred during the Devonian era,
0:24:21 > 0:24:23which began 400 million years ago.
0:24:24 > 0:24:28But there was precious little evidence of how it had happened.
0:24:29 > 0:24:32Imagination is very important in any science.
0:24:32 > 0:24:37You have to be able to think about things that you can't see,
0:24:37 > 0:24:42but exist in your head, and for a palaeontologist,
0:24:42 > 0:24:48it's a question of imagining such a world as we've never been a part of.
0:24:48 > 0:24:54The earliest evidence palaeontologists had was Eusthenopteron,
0:24:54 > 0:24:58a fish with the precursors of our major limb bones,
0:24:58 > 0:25:01dating from 380 million years ago.
0:25:01 > 0:25:04But the next complete fossil specimen came after
0:25:04 > 0:25:06a whopping gap in the record.
0:25:06 > 0:25:09We have an animal called Eryops,
0:25:09 > 0:25:13which is perhaps 80 million years later,
0:25:13 > 0:25:19which has got perfectly robust limbs with fingers and toes, so those two
0:25:19 > 0:25:25animals between them formed the sort of icons of the transition,
0:25:25 > 0:25:27with the fish at one end of the spectrum,
0:25:27 > 0:25:29and the tetrapod at the other end.
0:25:29 > 0:25:35A major anatomical transformation had taken place during this time.
0:25:35 > 0:25:37In the absence of hard evidence,
0:25:37 > 0:25:41palaeontologists settled on the theory that periods of drought
0:25:41 > 0:25:44had driven fish with proto-limbs onto land.
0:25:45 > 0:25:50It was very much seen that an animal like Eusthenopteron,
0:25:50 > 0:25:54while hopping from one drying pool to another, like a mud skipper,
0:25:54 > 0:25:58would actually enhance its capabilities on land,
0:25:58 > 0:26:01and that legs evolved from the fins
0:26:01 > 0:26:05while it was on land, trying to do this hop, skip and a jump.
0:26:05 > 0:26:09This is a hypothesis that kind of captured the public imagination,
0:26:09 > 0:26:14and it really had a big influence on people's thinking for several decades from about the 1950s.
0:26:14 > 0:26:19The only thing that could establish what actually happened was evidence.
0:26:19 > 0:26:22Fossils of a creature from the middle of this gap,
0:26:22 > 0:26:25which could reveal how the transition took place,
0:26:25 > 0:26:28but there was one candidate for the role.
0:26:29 > 0:26:35The only thing between Eusthenopteron and Carboniferous tetrapods with legs
0:26:35 > 0:26:39was, for many decades, Ichthyostega.
0:26:39 > 0:26:42Literally, that was all.
0:26:44 > 0:26:50Ichthyostega was an intriguing tetrapod from 360 million years ago,
0:26:50 > 0:26:53right in the middle of the fossil gap.
0:26:53 > 0:26:57Its anatomy seemed to nod to the fish that came before
0:26:57 > 0:26:59and the land animals that came later.
0:27:00 > 0:27:04But the only specimen in existence was frustratingly off-limits.
0:27:08 > 0:27:15Ichthyostega was in the hands of an eminent Swedish researcher, Erik Jarvik,
0:27:15 > 0:27:17who had unearthed a cache of well-preserved fossils
0:27:17 > 0:27:21on a pioneering expedition to Greenland in the 1930s.
0:27:22 > 0:27:25In those early days,
0:27:25 > 0:27:29these expeditions were really quite heroic, and it's a remarkable thing
0:27:29 > 0:27:31that they brought back the material they were able to.
0:27:31 > 0:27:35Conditions were really much more, how can I put it, primitive than today.
0:27:37 > 0:27:39On his return from Greenland,
0:27:39 > 0:27:41Jarvik set about a painstaking
0:27:41 > 0:27:43investigation of this new discovery.
0:28:01 > 0:28:05Jarvik was very hard-working and very single-minded,
0:28:05 > 0:28:09and he was also quite talented, but not immensely talented.
0:28:09 > 0:28:14Many things he got right, quite a few things he got wrong,
0:28:14 > 0:28:17and he would never change his mind.
0:28:17 > 0:28:20With Ichthyostega, Jarvik struggled,
0:28:20 > 0:28:25and there were parts of the anatomy that he was never able to make sense of,
0:28:25 > 0:28:28and he published it very, very slowly.
0:28:36 > 0:28:40But the academic convention of the time meant that if other
0:28:40 > 0:28:44researchers wanted to study this animal, they'd simply have to wait.
0:28:46 > 0:28:49Because Jarvik had charge of the material,
0:28:49 > 0:28:52it was felt to be his territory.
0:28:52 > 0:28:56The etiquette of the time was really quite distinctive.
0:28:56 > 0:29:00If somebody's in the middle of working actively on something,
0:29:00 > 0:29:03in particular if it is stuff that they have collected themselves,
0:29:03 > 0:29:04you don't just muscle in.
0:29:04 > 0:29:06That would be considered very poor form.
0:29:06 > 0:29:10The Stockholm crew had complete sovereign rights over
0:29:10 > 0:29:15not only the material they had collected,
0:29:15 > 0:29:18but really, the late Devonian of Greenland as a concept.
0:29:20 > 0:29:23Other researchers' response to Jarvik's initial findings
0:29:23 > 0:29:25only added to the delay.
0:29:25 > 0:29:31When Jarvik published his work, British and American workers ridiculed it.
0:29:31 > 0:29:33He was a sensitive chap,
0:29:33 > 0:29:36and the result was a lot of bottled-up anger.
0:29:36 > 0:29:41And it coloured his view of scientists outside Sweden
0:29:41 > 0:29:43for the rest of his career.
0:29:43 > 0:29:48And at this point, he felt disinclined to satisfy them
0:29:48 > 0:29:51by publishing any more about it.
0:29:51 > 0:29:53And he took the view that they could now wait
0:29:53 > 0:29:58and he would work very slowly for several decades.
0:29:58 > 0:30:03And he finally published his monograph in 1995,
0:30:03 > 0:30:06having outlived most of his first generation of critics.
0:30:06 > 0:30:12Jarvik's long silence left the field effectively closed.
0:30:12 > 0:30:14This was immense frustration,
0:30:14 > 0:30:18because the problem is that you can't really work on this kind of thing
0:30:18 > 0:30:20without the material.
0:30:20 > 0:30:23And if people aren't prepared to lend it to you,
0:30:23 > 0:30:26because they are "working on it",
0:30:26 > 0:30:29there's very little you can do about it.
0:30:29 > 0:30:33He would frequently sit at conferences and not speak to anyone.
0:30:33 > 0:30:36And he showed very little wish to engage in conversation.
0:30:36 > 0:30:41Somebody did try to suggest that he should pass it on.
0:30:41 > 0:30:44In fact, to Alec Panchen.
0:30:44 > 0:30:48But this caused an immense rift between Jarvik and Panchen.
0:30:48 > 0:30:53Not that Panchen felt it. But Jarvik did.
0:30:53 > 0:30:56And that scuppered anybody else's chances
0:30:56 > 0:30:59of getting their hands on it as well.
0:30:59 > 0:31:05So you had this huge gap between a fish at 380 million years
0:31:05 > 0:31:10and fairly well-known land animals at about 330-300 million years.
0:31:10 > 0:31:13And in between, you had Ichthyostega
0:31:13 > 0:31:15which was not very well-known at all.
0:31:15 > 0:31:20It meant that nobody else could really think about it.
0:31:20 > 0:31:22It was out of bounds.
0:31:22 > 0:31:27And the subject remained moribund for decades.
0:31:27 > 0:31:33Jenny knew that the only way to overcome the stifling etiquette
0:31:33 > 0:31:35would be to somehow find different samples.
0:31:35 > 0:31:38But Greenland was one of the only places in the world
0:31:38 > 0:31:41with the right kind of Devonian rock.
0:31:41 > 0:31:45It would be a very good area for an ambitious palaeontologist
0:31:45 > 0:31:48to get into, IF you can find the specimens.
0:31:48 > 0:31:54And the fact that Ichthyostega was known only from Greenland
0:31:54 > 0:31:58which meant, at the very least, an expensive expedition,
0:31:58 > 0:32:00meant that for many people
0:32:00 > 0:32:04this was probably too onerous and complicated to envisage.
0:32:09 > 0:32:11Then Jenny had an extraordinary breakthrough.
0:32:11 > 0:32:15Brooding about Greenland,
0:32:15 > 0:32:17she decided to ask the geologists
0:32:17 > 0:32:21at the Earth Sciences Department over the road
0:32:21 > 0:32:22about any trips they'd made there.
0:32:22 > 0:32:27One recalled that a student had been to Jarvik's area of Greenland
0:32:27 > 0:32:32in the early '70s, and had left some specimens in their storeroom.
0:32:32 > 0:32:34In notes from a student, it said,
0:32:34 > 0:32:37"We found tetrapods at three localities."
0:32:40 > 0:32:42And that triggered an alarm.
0:32:42 > 0:32:45Where is this material?
0:32:45 > 0:32:49Jenny went down to the basement to see if she could find the fossils
0:32:49 > 0:32:51that had been of little interest to the geologist.
0:32:51 > 0:32:55And he pulled out a drawer full of this material.
0:32:55 > 0:32:59He had no idea what it was he'd found.
0:32:59 > 0:33:04It turns out that what the student had found was actually material,
0:33:04 > 0:33:09not of Ichthyostega, but of a second animal
0:33:09 > 0:33:11called Acanthostega,
0:33:11 > 0:33:15which hitherto had only been known from two fragmentary specimens.
0:33:15 > 0:33:19And what the student had found was a block
0:33:19 > 0:33:25with three skulls of this animal together in a row.
0:33:25 > 0:33:29I was blown away. Absolutely blown away.
0:33:29 > 0:33:31I thought, "Oh, gosh!"
0:33:31 > 0:33:37She was tremendously excited, because suddenly this
0:33:37 > 0:33:44represented an opportunity to study a completely different animal.
0:33:44 > 0:33:48A contemporary of Ichthyostega's, but obviously just from the skull
0:33:48 > 0:33:51you could see that it was a very different animal.
0:33:51 > 0:33:56And so it had to tell us lots of interesting, new information
0:33:56 > 0:33:59about the evolution of tetrapods from fish.
0:34:01 > 0:34:03Keen to know more,
0:34:03 > 0:34:07Jenny managed to track down the student's field notebook.
0:34:07 > 0:34:11In his scrappy notes
0:34:11 > 0:34:16were altitudes and mountains,
0:34:16 > 0:34:20and exactly how he'd found this material.
0:34:20 > 0:34:24So we then knew pretty much where to go back and find this.
0:34:24 > 0:34:29So, I mean, the obvious thing to do was try and get back there.
0:34:29 > 0:34:31And go to the same locality.
0:34:31 > 0:34:35The future rolled out in front of me.
0:34:35 > 0:34:38I saw...I saw the future.
0:34:38 > 0:34:42What was likely to happen.
0:34:42 > 0:34:45It was astonishing that the only collection
0:34:45 > 0:34:51of other Devonian tetrapod material was about 200-300 yards
0:34:51 > 0:34:54from where she'd been working, and she didn't know about it.
0:34:54 > 0:34:56None of us did.
0:34:56 > 0:35:01That's luck, I'm afraid, by anybody's standard.
0:35:01 > 0:35:05Well, luck and timing play into it in a big way.
0:35:05 > 0:35:09But I think the key component, in a sense, one of the key components,
0:35:09 > 0:35:13is spotting the chances when they come up, and leaping for them.
0:35:13 > 0:35:19The next move was to get in touch with people in Copenhagen...
0:35:20 > 0:35:25..and try to get them to agree to organise a joint expedition.
0:35:25 > 0:35:27To go to Greenland,
0:35:27 > 0:35:31Jenny would need permission from the Danish authorities.
0:35:31 > 0:35:33Something no-one had ever previously managed,
0:35:33 > 0:35:37owing to academic sensitivities.
0:35:37 > 0:35:39They were always denied access.
0:35:39 > 0:35:44This was because people in the museum in Copenhagen
0:35:44 > 0:35:46didn't want to upset Jarvik.
0:35:46 > 0:35:51So there's quite a lot of political activity behind this, as well.
0:35:51 > 0:35:54Jenny saw that she had only one option.
0:35:54 > 0:35:56To go and meet Jarvik, face to face.
0:35:56 > 0:36:00Jenny and I went to a congress in Prague in 1985.
0:36:00 > 0:36:01He was there.
0:36:01 > 0:36:05She was, as I say, not a very forceful person
0:36:05 > 0:36:08in initial conversation.
0:36:08 > 0:36:11She's quite reserved, she's quite careful.
0:36:11 > 0:36:14Where others had failed, Jenny's calm approach
0:36:14 > 0:36:18and willingness to search for a fossil other than Ichthyostega
0:36:18 > 0:36:22apparently won Jarvik round.
0:36:22 > 0:36:25Although the conversation may have been initially a bit difficult,
0:36:25 > 0:36:27I suspect Jarvik recognised in some ways
0:36:27 > 0:36:29a slightly kindred personality type.
0:36:29 > 0:36:34And not a sort of person who would go around ridiculing him
0:36:34 > 0:36:36or in any way threatening him.
0:36:36 > 0:36:38And in that sense,
0:36:38 > 0:36:41I think she managed to charm him in a subtle sort of way.
0:36:41 > 0:36:43And he was fine.
0:36:43 > 0:36:47And that being the case,
0:36:47 > 0:36:52the people in Copenhagen were very willing to come on board
0:36:52 > 0:36:58and help get an expedition together to go back to Greenland.
0:37:03 > 0:37:09Jenny now faced organising the most challenging fossil hunt of her life.
0:37:09 > 0:37:11Enlisting her husband Rob,
0:37:11 > 0:37:14and her PhD student, Per Ahlberg, to help her.
0:37:14 > 0:37:18We'd never done anything like this before. I was actually terrified.
0:37:18 > 0:37:20I had no idea really what to expect,
0:37:20 > 0:37:22except that it's going to be difficult.
0:37:22 > 0:37:27We were going in helicopters, and everybody knows helicopters crashed.
0:37:27 > 0:37:29And polar bears eat you.
0:37:29 > 0:37:32We knew this was going to be a hard trip.
0:37:32 > 0:37:34We knew that we would be out in the field,
0:37:34 > 0:37:36camping 300km inside the Arctic Circle.
0:37:36 > 0:37:38We knew it was going to be cold.
0:37:38 > 0:37:41We knew it was going to be hard work, climbing up mountains.
0:37:41 > 0:37:42And we knew we were not very fit.
0:37:42 > 0:37:45My girlfriend knitted me a nice, warm, new jumper.
0:37:45 > 0:37:48I've still got it, too. It's got fish on it.
0:37:48 > 0:37:51I've still got the same girlfriend, too.
0:37:51 > 0:37:57In July 1987, a Danish support team deposited Jenny, Per and Rob
0:37:57 > 0:38:01on the side of Stensio Bjerg, in the remote northeast of Greenland.
0:38:06 > 0:38:08Now suddenly, here you are.
0:38:08 > 0:38:12There's nobody for 100 miles in any direction.
0:38:13 > 0:38:15That is isolated.
0:38:15 > 0:38:18Having set up camp and made things work on that level,
0:38:18 > 0:38:21we now had to go out and find something.
0:38:21 > 0:38:24And if we didn't find anything of any significance,
0:38:24 > 0:38:26it would be rather embarrassing
0:38:26 > 0:38:29and rather a lot of money spent for nothing.
0:38:32 > 0:38:36Looking for fossils can be a thankless task.
0:38:36 > 0:38:39Because most of the time, you don't find anything.
0:38:44 > 0:38:47For the first few days, we couldn't find where we were supposed to be.
0:38:47 > 0:38:49We weren't even sure we were on the right mountain.
0:38:49 > 0:38:50And we thought,
0:38:50 > 0:38:53"We're here for 6 weeks and not going to go back with anything?"
0:38:53 > 0:38:59We were walking on very steep scree slope,
0:38:59 > 0:39:01made up of small slivers of rock.
0:39:01 > 0:39:04Very loose, very insecure.
0:39:04 > 0:39:08And at the bottom, we could see what appeared to be a sheer cliff
0:39:08 > 0:39:10waiting for us to fall over it.
0:39:10 > 0:39:12So we gave up.
0:39:12 > 0:39:15And the three of us trudged back down the mountain,
0:39:15 > 0:39:18feeling very depressed and ashamed, as you can imagine.
0:39:18 > 0:39:21Jenny, as I recall, was getting quite worried about
0:39:21 > 0:39:25whether anything useful was going to come out of this.
0:39:25 > 0:39:32Because we were looking for white bone in darkish brown rock.
0:39:32 > 0:39:38So anything white caught our eyes and we thought for an instant,
0:39:38 > 0:39:40"I've found a fossil."
0:39:40 > 0:39:43But a lot of the time, it was bird shit.
0:39:46 > 0:39:49Almost one week in, the exhausted party
0:39:49 > 0:39:52launched a third attempt on the mountain,
0:39:52 > 0:39:54approaching it at a different level.
0:39:54 > 0:39:56One of us, I forget who now,
0:39:56 > 0:40:00picked up a little slab with a piece of bone on it,
0:40:00 > 0:40:02showed it to Jenny, who gave a kind of whoop,
0:40:02 > 0:40:07because this was part of the back of the skull of Acanthostega.
0:40:07 > 0:40:10It was a piece of the same fossil animal
0:40:10 > 0:40:13that Jenny had found in the drawer in Cambridge.
0:40:13 > 0:40:16She realised that they must be close to the area
0:40:16 > 0:40:18described in the student's notes.
0:40:18 > 0:40:21As we started hacking at the rock,
0:40:21 > 0:40:24hack a block off, break it up...
0:40:24 > 0:40:26another skull.
0:40:26 > 0:40:30We realised we are in this big kind of apron of fallen material
0:40:30 > 0:40:32from some locality higher up.
0:40:32 > 0:40:35We kept going up and it kept getting richer and richer,
0:40:35 > 0:40:38and I found a lower jaw actually disappearing into the rock.
0:40:38 > 0:40:43So there we were, and we had found the locality.
0:40:43 > 0:40:45Now, of course, once we'd done that,
0:40:45 > 0:40:48then we were really in business.
0:40:48 > 0:40:51The team had discovered a whole strata of rock
0:40:51 > 0:40:54full of Acanthostega remains.
0:40:54 > 0:40:58And it looked like it contained more than just scattered bones.
0:41:01 > 0:41:04The dream of the vertebrate palaeontologist
0:41:04 > 0:41:06is to find a complete, articulated specimen,
0:41:06 > 0:41:10with every bone in place, so you tip it out the rock and you can see what's going on.
0:41:10 > 0:41:13One of the specimens that we found,
0:41:13 > 0:41:16it was clear that it was a head at one end
0:41:16 > 0:41:18and then leading back from there,
0:41:18 > 0:41:24in sort of a glancing sunlight, was a row of bumps,
0:41:24 > 0:41:27which looked as though they might be vertebrae.
0:41:27 > 0:41:30We didn't know what we'd found.
0:41:30 > 0:41:32But we knew it was going to be exciting.
0:41:32 > 0:41:37It looked as if they had found one of palaeontology's holy grails.
0:41:37 > 0:41:38The first complete specimen
0:41:38 > 0:41:41of an early Devonian tetrapod.
0:41:41 > 0:41:44This was it. This was the key, really,
0:41:44 > 0:41:47to the rest of my career.
0:41:47 > 0:41:51The discovery of those materials was probably the most exciting thing
0:41:51 > 0:41:53after falling in love.
0:41:56 > 0:42:02The party packed a metric tonne of fossils into crates
0:42:02 > 0:42:06and returned to Cambridge.
0:42:14 > 0:42:17DRILLING
0:42:17 > 0:42:21Once home, they faced the monumental task
0:42:21 > 0:42:25of bringing the rocks to life.
0:42:25 > 0:42:27Here, you are dealing with an animal
0:42:27 > 0:42:29and you don't know what it's going to look like.
0:42:29 > 0:42:32Nobody knows what it's going to look like.
0:42:32 > 0:42:34And you are able to piece together for the first time
0:42:34 > 0:42:37a style of creature that nobody perhaps has previously seen.
0:42:37 > 0:42:41Trying to imagine what these animals were like in life
0:42:41 > 0:42:45is really what it's about for me.
0:42:45 > 0:42:48I kind of wish we had a time machine.
0:42:48 > 0:42:51That we could go back and look at the animals.
0:42:51 > 0:42:54Because a lot of us are zoologists at heart.
0:42:54 > 0:42:56These are animals that happen to be in the rocks.
0:42:56 > 0:43:00Jenny now assembled another team
0:43:00 > 0:43:05to undertake the painstaking work of fossil preparation.
0:43:05 > 0:43:07When I started working on that material
0:43:07 > 0:43:10using the adapted dental equipment that we use,
0:43:10 > 0:43:13picks and drills and so forth,
0:43:13 > 0:43:16I realised this was going to, er...
0:43:16 > 0:43:19This was going to take a hell of a long time.
0:43:19 > 0:43:24The Greenland rock is very hard, so it takes a long time to get
0:43:24 > 0:43:27a very small amount of material out of the specimen.
0:43:27 > 0:43:29You had these long periods of relatively
0:43:29 > 0:43:31methodical preparation,
0:43:31 > 0:43:34punctuated by great periods of excitement, so...
0:43:34 > 0:43:37You're obsessive in doing this work,
0:43:37 > 0:43:40because you don't know what you're going to find next.
0:43:40 > 0:43:41And it's absorbing.
0:43:41 > 0:43:44It can be nerve-wracking
0:43:44 > 0:43:49because you don't really know where the bone is.
0:43:49 > 0:43:55You have to be extremely careful and take it down bit by bit.
0:43:55 > 0:43:57It's all a matter of colour and texture,
0:43:57 > 0:44:00and being able to see subtle differences
0:44:00 > 0:44:03as you expose different levels.
0:44:05 > 0:44:09Finding out whether the Acanthostega fossils had legs was critical.
0:44:09 > 0:44:14They could be the key to understanding how limbs had evolved.
0:44:17 > 0:44:21I think we were pretty open-minded about it in the first place
0:44:21 > 0:44:25because for all we knew, it could have had a fin instead of a limb.
0:44:25 > 0:44:29I mean, other features of the anatomy suggested
0:44:29 > 0:44:31that it really was quite primitive.
0:44:31 > 0:44:36Jenny gave Mike Coates the job of preparing the body
0:44:36 > 0:44:40of the most complete-looking specimen.
0:44:40 > 0:44:42How much of the animal was there, we weren't sure.
0:44:42 > 0:44:46So, of course, part of the rest of that was unpacking blocks.
0:44:46 > 0:44:48Again, sitting in dusty museum basements
0:44:48 > 0:44:51just trying to fit these things back together again,
0:44:51 > 0:44:53how they'd been in the field before they'd been broken up.
0:44:53 > 0:45:01He started work on what we thought was going to be a humerus arm bone.
0:45:01 > 0:45:04And, indeed, that's what it turned out to be.
0:45:04 > 0:45:08And it was pretty comparable with the humerus of a tetrapod.
0:45:08 > 0:45:11The upper arm suggested
0:45:11 > 0:45:15that this must be a land-walking amphibian.
0:45:15 > 0:45:18But to their surprise, when Mike uncovered the lower arm bones,
0:45:18 > 0:45:22these resembled those of Eusthenopteron, the fish ancestor.
0:45:22 > 0:45:25It was an astonishing mix.
0:45:25 > 0:45:29So then he started working on the adjoining block,
0:45:29 > 0:45:31starting from the edge and working in.
0:45:31 > 0:45:35And the first thing he found is a digit.
0:45:35 > 0:45:42A row of elements joined one to the other, like fingers.
0:45:42 > 0:45:43So he found a finger.
0:45:43 > 0:45:48Digits meant a hand or a foot, not present in Eusthenopteron.
0:45:48 > 0:45:50But that wasn't all.
0:45:50 > 0:45:53So he went a bit further, found another one.
0:45:54 > 0:45:56And another one.
0:45:56 > 0:45:59And another one. And another one.
0:46:00 > 0:46:03And he thought, "Ah, I've found five.
0:46:03 > 0:46:06"Shall I carry on, or shall I just leave it?"
0:46:06 > 0:46:10So he thought, "Just for the sake of completeness, I'll do a bit more."
0:46:10 > 0:46:14And he went round and eventually came up with eight of them.
0:46:14 > 0:46:17And that was...
0:46:17 > 0:46:19when the fun really started.
0:46:19 > 0:46:22The assumption had always been
0:46:22 > 0:46:26that tetrapods had evolved with five digits.
0:46:26 > 0:46:29It made a huge impact, because it seemed so outlandish.
0:46:29 > 0:46:33And there were one or two people who wondered initially
0:46:33 > 0:46:35whether what they had found was simply the two limbs
0:46:35 > 0:46:37lying on top of each other,
0:46:37 > 0:46:39giving that effect. Understandably enough.
0:46:39 > 0:46:42But very quickly, when a few people had seen the materials,
0:46:42 > 0:46:46it was acknowledged that this was in fact exactly what they said it was.
0:46:46 > 0:46:51There had been a big debate for many decades about how digits had arisen
0:46:51 > 0:46:54and why they look the way they do.
0:46:54 > 0:46:56And the eight-digited limb of Acanthostega
0:46:56 > 0:46:59landed kind of smack in this.
0:47:00 > 0:47:02Jenny began to wonder
0:47:02 > 0:47:06whether she needed to rethink the most basic assumptions.
0:47:06 > 0:47:11I think as Mike was preparing the forelimb,
0:47:11 > 0:47:14it just became obvious
0:47:14 > 0:47:16that the forearms stretched out like that.
0:47:16 > 0:47:18Really couldn't bend very far.
0:47:18 > 0:47:22They just do not look like weight-bearing limbs.
0:47:22 > 0:47:27So we began to think of what else it could do.
0:47:27 > 0:47:30What was it being used for?
0:47:30 > 0:47:31It was a confusing picture.
0:47:31 > 0:47:33The arms didn't bend in a way
0:47:33 > 0:47:35that would allow Acanthostega to walk.
0:47:35 > 0:47:37And the eight-toed hand
0:47:37 > 0:47:41looked more like a paddle than a foot it could stand on.
0:47:41 > 0:47:43Then Jenny had a radical thought.
0:47:43 > 0:47:49What if Acanthostega's limbs and feet hadn't evolved on land?
0:47:49 > 0:47:55Perhaps limbs evolved before walking. Perhaps for some other purpose.
0:47:55 > 0:47:57Swimming.
0:48:00 > 0:48:05That idea, that limbs evolved in water first,
0:48:05 > 0:48:09was quite revolutionary.
0:48:09 > 0:48:13Maybe making their way through swampy, reedy, mucky streams.
0:48:13 > 0:48:16Paddling in water, rather than walking on land.
0:48:16 > 0:48:19In other words, something entirely different first.
0:48:19 > 0:48:22And then only later used for walking with.
0:48:22 > 0:48:25Just as she had with the stapes earlier in her career,
0:48:25 > 0:48:31Jenny's creative vision was turning the received wisdom on its head.
0:48:31 > 0:48:35But she knew she needed further proof.
0:48:35 > 0:48:38She focused on the skull.
0:48:38 > 0:48:40Inside the throat
0:48:40 > 0:48:43were a series of gill bars,
0:48:43 > 0:48:48which looked just the same as those that you find in fish.
0:48:48 > 0:48:51So it's gill breathing. And then Mike found the tail.
0:48:51 > 0:48:55Which had got long, long fin rays.
0:48:55 > 0:48:57Which is useless out of water,
0:48:57 > 0:48:59so that sort of completes the picture
0:48:59 > 0:49:01of primitive tetrapods
0:49:01 > 0:49:04living in water, being mainly aquatic,
0:49:04 > 0:49:07and using their limbs for swimming.
0:49:07 > 0:49:08Everybody expected Acanthostega
0:49:08 > 0:49:11to look like a terrestrial animal from the neck back.
0:49:11 > 0:49:13Nobody expected it to have gills.
0:49:13 > 0:49:15It was a paradigm shift.
0:49:15 > 0:49:17The decades-old textbook image
0:49:17 > 0:49:19of a fish lumbering onto land on its fins
0:49:19 > 0:49:21could only be wrong.
0:49:24 > 0:49:27Other fossil evidence of plant life supported the idea
0:49:27 > 0:49:30that these creatures lived in newly-formed marshland.
0:49:32 > 0:49:37It seemed that the very first legs evolved not for walking,
0:49:37 > 0:49:42but as a tactic for moving through dense vegetation in swamps.
0:49:42 > 0:49:46Things can be evolved for one purpose
0:49:46 > 0:49:48and then used later
0:49:48 > 0:49:51in a slightly modified form for another thing.
0:49:51 > 0:49:53And the idea that limbs
0:49:53 > 0:49:55were not originally used for walking
0:49:55 > 0:49:57might be counterintuitive.
0:49:57 > 0:50:01But I think that's only because as humans and as terrestrial animals,
0:50:01 > 0:50:04we kind of think walking must be
0:50:04 > 0:50:07the be all and end all of what limbs are for.
0:50:07 > 0:50:08But, of course, it isn't.
0:50:10 > 0:50:15Once Jenny was ready to publish, her findings were well received.
0:50:15 > 0:50:17I think she realised pretty quickly
0:50:17 > 0:50:20that this was Nature-standard material.
0:50:20 > 0:50:22That the journal, Nature,
0:50:22 > 0:50:26which is one of the most prestigious scientific journals,
0:50:26 > 0:50:29would actually publish this sort of stuff.
0:50:29 > 0:50:36From when we started publishing the full descriptions of Acanthostega,
0:50:36 > 0:50:38the head, the body, the limbs,
0:50:38 > 0:50:44it became the model for a Devonian tetrapod.
0:50:44 > 0:50:50Or a primitive tetrapod that could have given rise to later ones.
0:50:50 > 0:50:52And Ichthyostega was marginalised.
0:50:52 > 0:50:56But there was a remaining mystery about Ichthyostega.
0:50:56 > 0:50:59Jarvik, the Swedish researcher
0:50:59 > 0:51:02who had hung on to the only specimen for 50 years,
0:51:02 > 0:51:04had described his animal
0:51:04 > 0:51:07as having five toes.
0:51:07 > 0:51:11We'd also found a hind limb of Ichthyostega
0:51:11 > 0:51:13in the same expedition.
0:51:13 > 0:51:20And preparation of that showed that it had seven digits on its foot.
0:51:20 > 0:51:26So putting that together, a pattern of more than five digits
0:51:26 > 0:51:30seemed to be what early tetrapods had.
0:51:30 > 0:51:32If you go back and look Jarvik's specimen,
0:51:32 > 0:51:34what he thought was one big toe, cracked,
0:51:34 > 0:51:37with a lot of cracks in it, is actually these three toes.
0:51:37 > 0:51:39So again, I think he was a little bit annoyed
0:51:39 > 0:51:41that she'd interpreted it and he hadn't.
0:51:41 > 0:51:46Jenny Clack had again seen what others had missed.
0:51:46 > 0:51:51But Jarvik was unwilling to accept that science had moved on.
0:51:51 > 0:51:57He finally published his definitive text on Ichthyostega.
0:51:57 > 0:52:01And in it, he used photographic evidence of his own
0:52:01 > 0:52:04to dismiss Clack's specimens as freaks.
0:52:04 > 0:52:08Jarvik didn't really believe our story,
0:52:08 > 0:52:12or our interpretation of the evidence.
0:52:12 > 0:52:14So he considered that the material
0:52:14 > 0:52:16of Ichthyostega and Acanthostega
0:52:16 > 0:52:20were both mutants that we happen to have found.
0:52:20 > 0:52:24You know, we know how rare mutants are in normal life.
0:52:24 > 0:52:29And the idea that we had found two of them was a bit silly.
0:52:29 > 0:52:35He just had the mindset that he had this safe knowledge
0:52:35 > 0:52:39and that what we had found contradicted that.
0:52:39 > 0:52:40So it was wrong.
0:52:40 > 0:52:42Jenny's not like that at all.
0:52:42 > 0:52:44She's very open-minded about her work.
0:52:44 > 0:52:48One of the things that I appreciated very much being her student
0:52:48 > 0:52:53was the sense that the student was always welcome to disagree
0:52:53 > 0:52:55with the supervisors.
0:52:55 > 0:52:58I don't imagine Jenny has ever thought herself to be infallible
0:52:58 > 0:53:00in any aspect of this stuff.
0:53:00 > 0:53:03This, of course, is the mark of a really good scientist.
0:53:03 > 0:53:07Because that way, your science becomes self-correcting.
0:53:07 > 0:53:10You're not going to veer off to the side and land in the ditch
0:53:10 > 0:53:13which, in a sense, is what happened with Jarvik and his interpretations.
0:53:13 > 0:53:18You will continue to head onwards towards a more and more
0:53:18 > 0:53:22accurate understanding of the animals you're working with.
0:53:22 > 0:53:26Other palaeontologists embraced Clack's theory
0:53:26 > 0:53:28of the aquatic origin of limbs,
0:53:28 > 0:53:31opening up a whole new area of research.
0:53:31 > 0:53:35All of a sudden, Devonian tetrapods went from being
0:53:35 > 0:53:38a marginal subject area to one of the hottest areas in palaeontology.
0:53:38 > 0:53:40It's catalysed the whole thing.
0:53:40 > 0:53:44We are now finding Devonian tetrapods worldwide.
0:53:44 > 0:53:46And if you look at a graph
0:53:46 > 0:53:50of the number of taxa known of Devonian tetrapods,
0:53:50 > 0:53:51it's gone like that.
0:53:51 > 0:53:54So it's almost exponential increase.
0:53:54 > 0:53:56It's had a huge impact.
0:53:56 > 0:54:00It's as though the field had become moribund,
0:54:00 > 0:54:04and now it's been completely unlocked, and it's vibrant.
0:54:04 > 0:54:06It was pretty radical.
0:54:06 > 0:54:09Yeah, we rewrote the textbooks, effectively.
0:54:09 > 0:54:12How long that will last, I'm not sure.
0:54:12 > 0:54:14But that remains to be seen.
0:54:18 > 0:54:20The self-deprecating girl
0:54:20 > 0:54:22who never expected to do a PhD
0:54:22 > 0:54:26had reached the pinnacle of her field.
0:54:26 > 0:54:28Whoever you asked in the subject would say
0:54:28 > 0:54:30Jenny is the world leader
0:54:30 > 0:54:32in research on the origin of tetrapods.
0:54:32 > 0:54:33She's the great pioneer.
0:54:33 > 0:54:37She's the one who led the way and opened up this area
0:54:37 > 0:54:39that we others have kind of come in to
0:54:39 > 0:54:42and continue to contribute to.
0:54:42 > 0:54:46And she continues to drive that subject forward to this day.
0:54:46 > 0:54:50She is, for most of us, the leading worker in this field.
0:54:50 > 0:54:53And as a measure of this,
0:54:53 > 0:54:58we do talk about the Clack theory of the origin of tetrapods.
0:54:58 > 0:55:02And there are very few other workers in vertebrate palaeontology
0:55:02 > 0:55:07where a theory, a current theory, is immediately understood
0:55:07 > 0:55:11by virtue of the name of the person who came up with it.
0:55:11 > 0:55:16I think Jenny definitely deserves all the awards
0:55:16 > 0:55:18and status that she's getting.
0:55:18 > 0:55:21I'm sure she'd say she doesn't, but I think she does.
0:55:21 > 0:55:27It's characteristic of a really good palaeontologist that they have,
0:55:27 > 0:55:30how can I put it, the imagination
0:55:30 > 0:55:36to understand these wretched remains as a one-time living organism.
0:55:36 > 0:55:39And Jenny is very good at this.
0:55:39 > 0:55:45Jenny became Professor Clack in 1997.
0:55:45 > 0:55:48But her greatest accolade came when she was invited to become
0:55:48 > 0:55:51the first woman in her field to join the Royal Society.
0:55:54 > 0:55:58I suppose I had secretly wanted that for years
0:55:58 > 0:55:59but never thought it would happen.
0:55:59 > 0:56:06And I was nominated by the director of the museum at the time,
0:56:06 > 0:56:12and I thought, "It's not going to get anywhere."
0:56:12 > 0:56:16But it did. It was one of the most thrilling days of my life,
0:56:16 > 0:56:17when I got that letter.
0:56:17 > 0:56:20I don't think she made a great fuss about it.
0:56:20 > 0:56:23I don't think she went round saying, "Hey, look at me!"
0:56:23 > 0:56:27That's just not in her persona.
0:56:28 > 0:56:32I was immensely proud, and I went round shouting, "Hey, look at her!"
0:56:32 > 0:56:38But I'm still constantly amazed by how my career has gone.
0:56:38 > 0:56:41And it's not finished yet, of course.
0:56:41 > 0:56:43But, erm...truly astonishing.
0:56:46 > 0:56:50Since describing Acanthostega, Professor Clack has remained
0:56:50 > 0:56:53at the forefront of tetrapod research,
0:56:53 > 0:56:57with over 140 publications.
0:56:57 > 0:57:00And she continues to make new discoveries
0:57:00 > 0:57:02that fill the gaps in the fossil record.
0:57:02 > 0:57:06But she accepts that her theories could yet be superseded.
0:57:06 > 0:57:08All our discoveries...
0:57:08 > 0:57:09Fossils will remain,
0:57:09 > 0:57:13but the interpretations can be overturned any day.
0:57:13 > 0:57:15All this knowledge is provisional.
0:57:15 > 0:57:18And this is something that people don't really
0:57:18 > 0:57:19understand about science.
0:57:19 > 0:57:21That it's not about certainty.
0:57:21 > 0:57:24It's not necessarily even about facts.
0:57:24 > 0:57:27It's about questions. And the answers that you give.
0:57:27 > 0:57:31A lesson in life's impermanence,
0:57:31 > 0:57:34that perhaps only palaeontology's long perspective
0:57:34 > 0:57:36could have given her.
0:57:36 > 0:57:43We should remember that we are only here temporarily.
0:57:43 > 0:57:47We do need to bear in mind that
0:57:47 > 0:57:53something will evolve to take our place at some point.
0:57:53 > 0:57:54And I like to speculate about
0:57:54 > 0:57:57which group of animals that might come from.
0:57:58 > 0:58:00My betting is on rodents, actually.
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