In Our Time - Fossils

Episode Date: March 22, 2001

Melvyn Bragg and guests discuss the significance of fossils. In the middle of the nineteenth century the discoveries of the fossil hunters used to worry poor Ruskin to death, he wrote in a letter in 1851, “my faith, which was never strong, is being beaten to gold leaf…If only those Geologists would let me alone I could do very well, but those dreadful Hammers! I hear the clink of them at the end of every cadence of the Bible verses.”The testimony of fossils over the ages has been remarkably eloquent when we have wanted to listen; and now with mass spectrometers, electron microscopes and secondary X-ray detectors, these long dead organisms can speak to us of the past in ways they never could before.With Richard Corfield, Research Associate in the Department of Earth Sciences at Oxford University; Dianne Edwards, Distinguished Research Professor in Palaeobotany at Cardiff University; Richard Fortey, Senior Research Palaeontologist at the Natural History Museum.

This BBC podcast is supported by ads outside the UK. Thanks for downloading the In Our Time podcast. For more details about In Our Time and for our terms of use, please go to BBC.co.com.uk forward slash radio four. I hope you enjoy the programme. Hello, in the middle of the 19th century, the discoverers of the fossil hunters worried John Ruskin greatly. He wrote in a letter in 1851,

My faith, which was never strong, is being beaten to gold leaf. If only those geologists would let me alone, I could do very well. But those dreadful hammers, I hear the clink of them at the end of every cadence of the Bible verses. The testimony of fossils has been remarkably eloquent when we've wanted to listen. And now with mass spectrometers, electron microscopes, and secondary X-ray detectors, these long-dead organisms can speak to us of the past in ways they never could before. With me to discuss the place of fossils in history and the impact of the latest techniques in understanding them, is Richard Corfield,

research associate in the Department of Earth Sciences at Oxford University, an author of a new book called Architects of Eternity, The New Science of Fossils. Also with us is Diane Edwards, distinguished research professor in paleobotany at Cardiff University, and Richard Forty, senior research paleontologist at the Natural History Museum, and author of Trillabyte, exclamation mark, eyewitness to evolution.

Richard Forty, great breakthroughs in paleontology were happening in John Ruskin's time, as we've learned. But the evidence of some of the fossil record has been plainly on display for thousands of years. Can we start with the Greeks in this as so much else? I mean, what did they make of the fossils in the rocks? Well, there was a common belief that the remains of large fossil mammals that were eroded out of cliffs in the Greek islands were the evidence for the gigantomachi,

the battle between the gods and giants, with the gods triumphant. and other fossils were regarded as physical proof of the existence of gigantic heroes. There was very little in the way of what you might call scientific study of fossils, although, as usual, Aristotle had a few wise words to say, but the scientific appreciation of fossils was ignored, really, in classical times. But there was something from, as I understand it, and I've just been reading up at this, obviously, from Pythagoras and Herodotus and Anaxia.

Amanda, that fossils were to do with water, that they'd come from water. Is that right? Yes, I think it was recognised that water must have once occupied areas, which it did no longer. But even in the Renaissance, there were scholars, Leonardo da Vinci, for example, really recognized quite presciently that there were major inundations that must have covered. of the land. But his line really wasn't taken up until really until the 17th century.

So the story is sort of very spread. Little Greek, less Latin, nothing much else until the Renaissance. Yes, it was a very late developing science, if you compare it with, say, astronomy or physics. Did again, did Leonardo, just to tease out the history a little bit more, did Leonardo say

anything which, as it was set it on its course or something you can draw now as saying, yes, he kicked that bit off? Well, I think it was unpublished, it was in his notebooks, and like many of his notebook's writings, they seem prescient in retrospect, but were rather ignored at the time. What were there, though? What did you say? I believe he noticed that some of the shells were of similar types to things that could be found around the Mediterranean today, and that therefore

the disposition of land and sea must have changed. Is there any accounting for the lack of interest in what has become such a fascinating and interesting topic over the last, say, 100, 150 years, Diane Edwards. I personally don't know of one, but it does seem that things started happening in the middle of the 17th century. And an unsung hero of paleobotany might be Robert Hook, who's known as a physicist these days, but he was polymathic. And he was the first person who actually looked at petrified wood, wood that's preserved as a rock, and worked out how it formed. He had a microscope, and he also looked at decaying vegetable matter

and said, well, not much of this is going to become fossil. And then this was taken up by later workers. So they had a very good grasp of what was going on then, but I think very many of them were reluctant, on religious grounds to actually come out and say what they actually thought fossils were. But I think they believed it. Yes, but looking just one more thing,

before we get on to the 17th and the 18th century, many men and women must have seen the fish in rocks, and they could account for this if they were very religious by the flood. Were there any other subversive accounts that you can think of over those nearly 1,500,000 years? I don't know of any. Perhaps you do, Richard, too, how many could research this? I'm just thinking about it. One of the interesting things about the history of paleontology is this enormous dead zone between the time of the ancient Greeks and the 17th century,

which is when the ball started rolling and sort of reached takeoff velocity in the 19th century, because Herodotus, Pythagoras, Empedocles, and Anaximander had noticed that there were invertebrate fossils on land. The remains of what were clearly gastropods, types of mollocks, which were only known from ocean waters, and they were on land, and so they made this connection that there must once have been sea where now there was land, and Pliny and one or two of the Romans took it up, and then interest in paleontology just kind of dissolved for another thousand

years, more than a thousand years, until in the 13th century, Ristora Arezzo came up with the idea of the deluge, and of course this immediately gained currency, especially in a kind of clergy-driven environment of the day, and stayed there until Leonardo da Vinci in the 15th century, who actually reconnected with the Greeks and, you know, was dissatisfied with the deluge theory than what became known as the Neptunian theory. And there was also, you know, a kind of popular idea of the day, a pop culture idea for the explanation of fossils in the sort of early medieval period is that just that they were sports of nature put there by God, you know, as a bit of a joke just to keep people on their metal. But it was Leonardo who really, you know,

reconnected with the Greeks and established fossils or paleontology on a firm scientific footing. His notes are in his thousands and thousands of words in mirror writing. And then from then you had Agricola in the 16th century who actually coined the term fossils. And that's where we have the term from. And it started to develop from that. But really, as I've said, accelerated only in the 19th century. Agricola's interests, of course, were mostly mineralogical.

And he really set the science of mineralogy, which of course is part of geology on a modern course. and had relatively little to say about fossils themselves. But it was all part of a general revival in the interest of the earth as an object of scientific study, which kind of set the scene for other scientific explanations to follow. You could argue that paleontology and geology at the time of agricula in the 16th century hadn't really separated into two separate disciplines. Well, let's move forward quite steadily in this.

In the 17th century, we have Samuel Pr. peeps praising somebody called Edward Cluid in his diary. Now, what was Diane Edwards? What was he praising about Clued? What was Cluid's theory of fossils? Well, Edward Lloyd was the deputy curator or keeper at the Ashmolean Museum, which had a collection of both animal and plant fossils as well as minerals. And he produced the first catalogue for the Ashmolean.

He was a very poor man. He came from Montserestray in North Wales. He was a great naturalist, a linguist. but he needed money to publish this catalogue. And so he enlisted the help of people like Sir Hans Sloan, Samuel Pepys, Isaac Newton, and they all got together, and they paid for the publication of this small catalogue, which has the first illustrations of fossil plants, as far as I know in it,

and these are Welsh plants. And Samuel Pepys and Hans Sloan are said to have drunk a toast on the day that it went to press. What was his explanation of the theory of how fossils had arrived, where they arrived. He thought they were freaks of nature. He thought they'd been put in place by God. Yes. He had a colleague called John Ray, who was a great botanist

and a chap interested in classification, and he predated Linnaeus in this. And John Ray knew what fossils were. And they had long discussions on this. But Floyd never really came out and said that they actually were living organisms. He had a strange idea called the spermatic principle, which was that, you know, inside the tip of it, every male sperm there was a little homunculus and that this could only come out when it was fertilised.

And his idea was that fossils were kind of sports of nature because the womb of Mother Earth had sort of semi-fertilized this spermatic principle. And so this is where fossils had come from and why they were found in such so often fragmented because they were partially formed by, as it were, inadequate fertilization procedures. He did like the scenario for the next American blois.

He did find the first trilobite too, around, or figure the first trilobite, around the town of Flendilo. And he referred to them as diverse flatfish. So in the 18th century, it's gathering force in this country, anyway. And this country seems to be playing quite a big part. This country, I mean, the United Kingdom seems to be playing quite a big part, a part. A lot of people are engaged in this. Richard Corfield, when do you think it comes of age, does it begin to gather together in the 18th century? pushing it forward then what are they telling us

we've mentioned Linnaeus or Dehoun's mentioned Linneus already I mean without pushing to plug Oxford too much I mean one of the foci for foci for you know the coalescence of what I now call the new science of fossils was the University Museum

but even before that there were great paleontologists and geologists working in and around Oxford associated with the clergy it has to be said and thinking about Buckland and William Smith and William Smith was the father of the geological map, which is an often denigrated part of paleontology and geology in present day.

But in fact, is a way of seeing the way time passes simply if you walk across the landscape because rocks of different age outcrop in different places. And in certain places in the present day, I'm thinking about the classical Bottagiani Gorge section in central Italy, you can simply walk up a road and walk through time. So these were the kind of ideas which were being established at the beginning of the 19th century. William Smith, of course, used this as a pragmatical guide to strata. He had himself no particular religious axe to grind. He was a practical man, a driver of canals and a surveyor.

He used the strata as a very practical means, and the fossils in the strata, as a very practical means to know where he should drive his next canal. And the incorporation of his ideas about the succession of time into the scientific world was quite a protracted one. Who was this practical man to come along and tell us how we should think about the great workings of God? But the implications of the map and the succession of strata, of course, lie at the base of understanding geological time itself. Is this time, is this the time when the conflict is beginning to arise

between the earth as dated as it were by the theologist, Archbishop Usher, 4,04bc, and the fossil paleontologists saying, something else of a different order is going on? I think it was probably much earlier than that. I think Floyd himself appreciated that sedimentation, from looking at landfalls, probably took a lot longer. They appreciated that it would take an awful lot of time to actually produce all these.

successive deposits with fossils in them and that it was far greater than Ashbridge-Bersh would have calculated. So yes, I think there was a gradual awareness throughout this period, right from the end of the 17th century. I think that it's a sort of symptomatic of the tension which was existing between the clergy and a sort of nascent science, which actually wanted to look in a different way more or less objectively as far as scientists are able to do that. the evidence of the fossil record. But the recognition of absolute time

is, of course, the 20th century invention, Ernest Rutherford and Frederick Soddy. And there's this Oxford laying on of hands of a paleontologist, as you describe in your book very well. Let's just come to the end of this at a very brief historical run through. Do you think it comes of age in the sense of gathering real force

about the time of Huxley? I do. You do, Richard Cawford. Could you tell us why you think that? Huxley, Darwin's Bulldog, and so on. Well, to me, you know, the Victorians had really recognised,

or at least were recognising a new theology, if you like, which was their interest in science. And the Oxford University Museum is nothing, if it's not a temple to that particular Victorian theology. And, of course, Darwin had, in the 1850s published origin of species by natural selection and his great champion, because Darwin himself was quite a retiring,

not to mention man of ill health. Huxley was his champion and, in fact, encouraged him to go further than he did. I'm reminded of a line that Darwin had included in an early version of origin of species. Natura non-facet salt of nature does not make leaps. And Huxley said, well, you know, why do you hobble yourself thus unnecessarily?

You know, why does nature not make leaps? And of course, Darwin was a product of his times, as Steve Gould has noted on more, than one occasion and liked the idea of gradual notions. It sort of fitted in with the mores of the age. But Huxley was a visionary in the sense that there was no need to hobble yourself to this kind of social context. And of course it was 100 years later that Steve Gould himself and Niles Eldridge

came up with the theory of punctuated equilibrium, which vindicated Huxley's idea. Then in fact we now know that under certain circumstances, evolution can proceed in Leaves. But from my perspective, the great debate of 18, when Huxley had a run in with the Bishop of Oxford. Yeah, Soapy Sam, he was called by the gutter press of the day for his slick tongue. And this was, in a sense, it's a kind of media fabrication.

There's several different accounts of it. But it appears that the undergraduates of the day then as now like to see their academic elders, as it were, have a good verbal fisticuff. And they goaded Wilberforce into asking Huxley, who had not even intended to attend that debate that day, whether it was through his grandfathers or his grandmother's side that he claimed dissent from an ape. This immediately showed that Wilberforce A had not understood very much

about the theory of evolution as promulgated by Darwin and understood even less about the nature and magnitude of geological time. And Huxley is reputed to have said, the Lord hath delivered him into my hands, and standing up, said that if the question was, would he rather claim dissent from an ape, or be related to a man who used his mental intellects to ridicule a reason scientific debate,

why then he unhesitatingly affirmed his preference for the ape. Do you, Diamond, do you think that Huxley is a keyer figure in paleontology as Richard Corfield claims he is? I wouldn't have thought that Huxley was a great paleontologist, but he certainly was a great advocate for the subject. He was not a paleobotanist, and my main interest is in paleobotony. And paleobotany with Huxley and his cronies really wasn't considered at all. And most of the work then was being done on the continent.

The great monographs were being developed in paleobotany at that time and they were accumulating a lot of data. But it is interesting that I think the roots of modern paleobotany are in those people who are constructing the monographs because they went a lot further than naming and describing their fossils. Right. Can we come to what fossils tell us now? Richard Fordy, can you just say briefly how a fossil is formed? To preserve a fossil, you need something with hard parts that is capable of being preserved in a sediment.

The vast majority of fossils are of things like bones, leaves, skeletons, teeth, shells. They are deposited in a sediment, which is covered by more sediment, which ultimately becomes rock. The rocks are then very often through earth movements elevated above sea level, where you can wander along with your geological hammer, tap the rock and take out the fossil. Just occasionally you get very special geological circumstances that preserve whole faunas or flora's. That is, you will get delicate, soft tissues preserved.

And these rare occurrences, of course, are immensely important in understanding the richness of life. Normally, fossils give us a partial view, the view of only those animals and plants, with hard, preservable parts. But they're not uncommon. There's a common misconception that fossils are rare things, but actually, as soon as you start looking for fossils, you will find them.

They're not, the record of life is extraordinarily prolific. In your book Trilobite, you write about your researches under this evolutionary forerunner of the horseshoe crab, and you write, I have pushed half of Europe across half an Atlantic. I've closed ancient seaways and opened up others. I've been able to name an ocean greater than the Mediterranean and then condemned it to perdition. So what is it about the trilobite

that enables you to act as it were, people would say, sort of a bit like God, really? I mean, can you tell us what a trilobite is and why it is so useful and enables you to write a sentence like that? Well, we're going back a very long way into the past. We're going back to three or four hundred million years into the past. and this is a time when we know little or comparatively little about geography.

Most people these days, most educated people have heard of Pangaea, the time when all the continents were conjoined in one great mass, which then split apart to give us our present-day continents. Well, with the Trilobites, we're going back to a time even before Pangia, when the continents were once again dispersed, and we used the trilobites. Can you just tell us what the trial... Tell everyone what a trial is. Trilobite is a distant relative of the crustaceans and the insects,

one of the jointed-legged animals. It was a marine creature with thousands and thousands of different species that were, if you like, one of the dominant life forms of the Paleozoic of the period beginning about 540 million years ago and going up to about 250. A long period of time. They had 300 million years of wandering about the oceans. Now, because they were so diverse, and because they had species that were confined to particular ancient continents, you could use them in a sense almost like postage stamps issued by those ancient continents to define their limits.

So I could use trilobites to draw out maps of the world, starting with a trilobite in your hand, you finish up with something which embraces most of the world. We could recognize the existence of former oceans because they separated two great areas of different types of trilobite faunas. So, I mean, the point I was making there is that study of fossils may seem to some people slightly esoteric, but from such studies you can go to things which have global significance. Same points made by Richard in his book,

that starting with something as humble as a phoromipherin, you can study past climates, past atmospheres, major changes. Can we just stick to this idea of measuring time from fossils? I mean, how is it Richard Corfield? How is it possible accurately to measure time? You spoke to Richard Forty in your book about half a million years and so on, well, that seems a bit rough and ready. Can we just talk about how clear you get to measure?

measuring time. I think... How near you get to measuring time accurately? Yeah, I think, well, the thing to recognize that there's two types of time in the fossil record, there's relative time, and that's the province of a sub-discipline of paleontology known as a

stratigraphy, and this is the way that rocks as seen in the field or down core in an ocean core are divided up, and there's various ways of recognizing the passage of time. Biostrategography is by recognizing evolution of different groups and

and different lineages of organisms within groups. And one of my favourite stories in architects is concerns two fine Edwardian ladies, Gertie Ellis and Ethel Wood, who used a particular group, another ICT group, I'm afraid, of fossils called graptolites, to divide time in the lower Paleozoic, 540 million years to about 400 million years. And they worked with a guy called Charles Lapworth, the University of Birmingham,

and tramped all over Wales on the Welsh borderland. recognizing that these tiny fossils, which look like nothing more than a hacksaw blade in the rock, changed their form sufficiently quickly that you could in fact use these distinctive types of form to recognize different layers of time in the rock, and then you could go elsewhere, for example, to Sweden and Estonia, the Baltic provinces, and recognize the same succession of forms, and so it was possible to recognize the same slice of time in different parts of the world. And this is the recognition of relative time.

The question of how you then make the transition from relative to absolute time is dependent on the discovery of radioactivity and the discovery of radioactive decay specifically, which is discovered by Rutherford and Soddy at the beginning of the 20th century. And they discovered that certain elements decay spontaneously, and I'm talking about uranium and thorium, which were the elements that they were particularly interested in, into other elements and varieties of elements,

which are actually called isotopes. And this decay chain, if you like, has a constant statistical time associated with it and ends up at a stable end product, which is normally a variety of lead. And so this might be for 100,000 years, for example, no, 400 million years, for example, is a good decay constant for uranium to lead.

And by recognising the amount of, as it were, starting product in the rock, and then the end product in the rock, the proportions of the two, uranium to lead, you actually know how long the rock has been there. And if you can bracket biostratographically dated rock, relatively dated rock, then you have the passage of time. Dynum, could I have your comment on this measurements of time in these vast ways?

What's your view of this? Well, unfortunately, it's only in recent sediments that we can actually date fossils, themselves accurately. And this is where another element comes in, and this is carbon. And we can, I think, now, how far can we go back with carbon? 70,000. Yes, yes.

And this is where technology has improved enormously, so we actually take very small fragments of fossils now in the recent past and actually date them to a few tens of years almost. So this technology has made a big difference in actually dating fossils. And when you date them to within 10 years almost? Well, it's a bit... All right, 20. I'm just quoting you.

When you do, what can you tell around them? What do that, how can you, to use the wrong word, how can you flesh that out? What can you get from it? Can you give us an example of, yes, I know this happened 65,000 years ago at about this particular time. And from that, I can conclude this about what life was like and what... Certainly using radiocarbon dating, we can find out a lot about the quaternary period, which is the period of ice ages, where we have successive periods of very cold climates and warm climates.

And we can take the interglacial, the warmest part of that, and we can actually look at cores through peats and sediments and take out plants from these and date them. And so we can actually find out how long it might have taken to become colder. Yeah. And this is refined by other isotope work. But that's something we can actually do by taking plant parts. In terms of our own history, of course, this is vital

because man, our own species, was spreading out and retreating from the advancing and retreating ice sheets and probably glacial history, as revealed by the fossil chronometers, is one way of unpicking our own early history in Europe and Asia and so on. You think we were determined by ice? Well, there is some people maintain that Neanderthal man, for example, now recognised as a separate species, was cold adapted,

a specialist for coping with icy conditions. So our own history has been uniquely bound in with climatic oscillations in, geologically speaking, the relatively recent past. You know, for us, people around this table, a million years is not very much time. I mean, which I gather we've had ten ice ages in the last million years, but can I come back to this time?

Can I come back to this idea with you, Diane Edwards? is it Carl W-O-E-S-E-C? How do you pronounce the name? Carl Woz? Well, I suppose if I have a German, I'd say Versa. Versa, yeah. Wos said to have discovered that there's a clock in every cell, every cell. And it tells us how long it's been since that cell moved away from its common ancestor.

And therefore that gives us an entry point to notions of time, which is very illuminating. Now, can you just unravel that a bit, please? Well, this is based on the sequences of nucleotides and the rate at which these bases change through time. And if we assume that they change uniformly through time, then we can look at examples of living organisms which one would suspect have evolved at different periods in the past

and actually calculate at what time they diverged. How does it work in this cell? It seems extraordinary. Every cell has this clock in it. I mean, a clock is a very graphic word. Can you just spell it out a bit more? Well, everyone knows about DNA, and we all know that DNA is composed of chains of nucleotides. And these are his clocks.

If we actually change a base, then the protein that's created, or the enzyme that's created from that sequence of bases might change, and then for have an influence in either the development or the appearance of an organism. And so by knowing the timing of the changing of these bases, then this is your clock. Anything tried Richard Forty on that? Well, one of the extraordinary discoveries of the last few years

is that we share common genes right down the evolutionary tree. It's the final confirmation that evolution must have happened, if you like. We have genes in common with the humblest bacterium. So common ancestry, which was one of the great debating points in the 19th century, is no longer in doubt. And we can scale the changes that have occurred to the genome. This is what this clock is. Changes have been cumulative. The genome, by and large, has got bigger.

Complex changes have been acquired. And you can trace this almost like a genealogy. So it's another way of getting at time. And in this case, it gets to really. really deep time, because these divergence at the cellular level happens not merely hundreds of millions of years ago, but thousands of millions of years ago. I was going to get on, I was going to try to tackle deep time, so here we go. Deep time, we're talking about 2,500 million years ago, which is, frankly, as far as I'm

concerned, inconceivable, but that's what you're talking about. Now, can you tell us how fossils can give us real insights, that is, insights that, yeah, real into deep time and how what's going on there Richard Calfield. The problem of course is that 2.5 billion as I prefer to think of it. Actually an easier way of thinking about the passage of time is to remember that the earth is 4.5 billion years old and that 2.5 is approximately halfway between the formation of the earth and now. And then if you scale that by thinking that fossil life on earth started 540 million years ago, 0.54 billion, then it gives you an idea of where we are in time.

In other words, we're two-thirds of the way back, approximately to the beginning of the Earth, the formation of the Earth. And the problem, of course, is that the fossil record at timescales of 2.5 billion years is not very helpful at all because it's at a time before Shelley fossils had evolved. In fact, Shelley fossils,

on which most of 20th century and certainly 19th century paleontology was based, in fact, turned out to be. very unhelpful when you're contemplating deep time, which incidentally is a phrase originating from the American writer John McPhee. It's almost a paleo cliche these days, but it was John McPhee who coined it. And Richard's quite right when he talks about the molecular clock. Technically, it's known as ribosomal RNA, so I'll explain in just a second, is the only way of getting at these events, the divergence, for example, of the most fundamental.

differences between animals, the protostomes and the deuterostomes, which occurred way, way back at about 2.5 billion years ago. You can only get at this through looking at cellular clocks. And the cellular clock works in much the same way as the uranium clock, which I talked about earlier. Statistically, mutations will accumulate an approximately constant rate given enough time. and if you look at certain parts of the cell which are highly conservative, i.e. absolutely vital for the functioning of all life, which is what this ribosermal RNA is, then you know that we have it today

and that the very earliest organisms, bacteria and pre-bacteria, must have had it too, because this RNA, as it's colloquially known, is part of the mechanics by which the DNA is translated into the functional chemistry of the cells, the proteins. So our RNA clocks are a different way of addressing deep time and a more flexible way than fossils. I think it would be wrong to give the impression that there were no fossils in these early periods of time. In the pre-Cambrian there are fossils that go back well to 2.5 billion years. They're

very simple fossils. They're mostly matte-like forms called tromatolites that form strange cushions. and from inside the stromatolites in exceptional circumstances, you can find the fossils of bacterial and even algal cells that give us a real record of this very early history of life. Can I ask a final question of you, Richard 40, about this deep time? Henry G, talking about this concept, said that it's sort of cocktail party talk. I think that was actually his phrase on a radio program.

These are merely isolated points which can't be connected what we're finding out about deep time from fossil evidence. Well, I think G's assertion is actually absurd. The story of paleontology over the last 20 years has been of progressively investigating deeper levels of time. And in the right circumstances, finding out extraordinarily intimate details of events that happened a long time ago. Just because something is distant doesn't mean to say it's unapproachable. That is, we can still find a geological record of something which enables us to study it. there are, of course, there are gaps, and those gaps have to be filled in by other means,

such as molecular means, such as Richard was describing. But it's very hard to grasp 2,500 million years. All of us find a problem with that. But that's not the same thing as saying it's impossible to find out about it. It would be like saying, oh, we can't find out about the origin of the universe because it happened so long ago and so far away. Of course, you can ask the right questions, the right scientific questions, and you can find out a surprising amount.

Let's come back to what most paleontologists do, which is a garden, book of fossils. And I'd like to talk to Diane Edwards now about the place in Aberdeenshire, the Rine Ely Clart. Can you tell us why that is so important and what it gives? Well, this is one of these rare events where whole ecosystems are preserved. I work on the earliest land plants, and these are the plants that transatlantic. third terrestrial environments and also change the atmosphere. And in Riney in Aberdeenshire, we have 400 million years ago a hot spring deposit. The hot springs would have been very similar to those in Yellowstone today.

And so plants that are growing around the hot springs were actually flooded by this water, which was rich in silica. The silica preserved around the plants. And so not only do we have the plants themselves, but we have the animals that lived in the debris. We have spiders sitting in sporad. eating mites. We have algae growing in the pools.

We have shrimps in the pools. We can see the development of soils. It's an absolute godsend to paleo potany. It's, well, I think probably the most single, most important paleo-botanical site that we have in Britain and in the world. So this is 400 million years ago. Yes. So we're getting rather familiar with this now after a deep time. Just down the road, really.

Can you give us some examples of what you can draw from this clearly? intensive, a unique site. What sort of information does it give you that you can give us pictures of what's been going on now? Well, those plants were quite unlike anything we have today except for one group, and so if we didn't have this fossil

record, we would not know what the earliest land plants were like. The molecular people can tell us when they arrived, but we do need the fossils to tell us that they were just collections of stems. But recent research has shown us that we can look a little at the physiology of these plants. We can see how they were growing. We can see

that they suffered major water stress from the way the cells are constructed. We can even say something about the carbon dioxide concentration of the atmosphere by looking at the ways in which they were taking up carbon dioxide. These things had very few pores in the surface to absorb carbon dioxide, and this fits in with the models that suggest

that carbon dioxide concentration then were 10, 15 times higher than they are today. And so we can use these plants not only to reconstruct the affidities, we can actually look at their ecology, their reproductive biology, and even the ways in which ultimately plants can relate to the drawdown of CO2 in the atmosphere in the Paleozerg. And in the Rhinichurch as well, there are animals, which show that certain elements of the ecosystem were already present. Oh, absolutely.

There were almost certainly predatory spiders. There were mites that served to break down plant tissue. so we have the beginnings of a terrestrial ecology, even then, right at the beginning, that we can still recognise today. So these kind of insights into geological past are truly wonderful and indispensable, really. Is it true, Diana, just to finish with this particular part,

would you say that that is an infinite resource up there in Aberdeenshire that you will just discover more and more about it, the more you can bring to bear in it through modern technology of examination? I don't think technology has helped us very much with the Rani Chert. What I would like to know is whether or not these plants were acting as Yellowstone plants do today in accumulating heavy metals from this environment with modern technology with lasers and various kinds of analysis.

I could do that. But no, we've been doing the same sort of thing with the Rani Chirte. It's a very small exposure. It's just one field. We are still finding out new things about the plants. for example, if we look at a fern today, there are two parts to its life cycle. There's the fern that we know and grow,

and then there's a very tiny, very delicate part, which is the sexual part of the life cycle, which is a separate plant. And it's been a very long-standing controversy since the last century in botany as to what this tiny, delicate part was when plants first came out onto land. And lo and behold, for the first time,

we actually have the first parts, the sexual part of the life cycle of these fern ancestors in the Rhinetert. So we're still discovering. But ideally what I would like to find is the Rhinichert in the Ordovician, for example, would be no plants first got onto the land. It's around about 450 million years ago. There we just have the spores of the plants,

and the plants themselves have completely disappeared. We have no fossils. So we need more than Rhinicherts, but they're a long time coming. Briefly, Richard Cawfield, can you briefly tell us what is new about paleontology now? You talk about the new signs of false. I personally think that we actually use a lot of new technology to investigate paleontology today. I mean, we've talked a bit about ribosomal RNA techniques, this thing that Carl Woz developed as recently as 1977.

Mass spectrometry has been around somewhat longer. This is this technique for recognizing these different varieties of elements known as isotopes. And we've talked about the spontaneous decay of uranium to lead as a chronometer of deep time. But in fact, we can also use a different variety of isotope, the so-called stable isotopes, which do not spontaneously decay, to investigate the temperature change in ancient oceans, as long ago as 400 million years, in fact, at the time of the Rhinie Church,

we now know something about the way the temperature changed in those oceans and those atmospheres through looking at isotopes. And through another suite of isotopes, the carbon isotopes, we've been able to track carbon dioxide changes. very well in fact over the last 100 million years which is between now to well into the time of the dinosaurs and in fact it's through the use of carbon isotopes in the geological record this aspect of the new science of fossils where we take an organism

which I'm particularly fond of the planktonic pheromina and we digest them break them down into their component atoms and measure the atoms that we're able to know the carbon atoms that we're able to know that the greenhouse effect actually exists there's no debate that the greenhouse effect exists. The debate in the present day is how fast our greenhouse gas concentration and our atmosphere is changing. And one of the things that we've been doing in Oxford is to look at a time which appears to be a mirror image of our current greenhouse plight, which occurred 55 million years ago when the earth warmed by 8 degrees centigrade. And this is twice the

temperature difference between now and the last glaciation. And it's only through these new techniques applied to the science of fossils, what I call the new science of fossils, that we can actually address climatic, for example, questions. Richard Fortier, do you see many benefits coming from applying the latest technology to paleontology? Well, curiously, it serves to invert a classic phrase. We used to say the geologist's dictum was, the present is the key to the past, and it seems that for the future, the past may yet prove to be the key to the present as we investigate global warming.

Global warming, of course, you said very briefly, I don't. You said this is rather good for you. It releases more sites. I'm not sure I did say that. Global warming certainly could be good for plants, and we can use plants to track global warming in the past, and this has been done. I think one of the breakthroughs for paleontology has been the discovery that these pores in the surfaces of the leaves can actually change

and the higher the carbon dioxide concentration, the temperature, the fewer the pores. I'm afraid that's all we have time for. Thank you for listening. We hope you've enjoyed this Radio 4 podcast. You can find hundreds of other programmes about history, science and philosophy at BBC.com.com.com.com.com.