The Discovery and Impact of DNA

What is the force at the heart of life? What is the engine that drives it forward? That links all living things from the smallest to the largest. That links families through generations in looks, in personality, in health. and in sickness. Scientists had searched for the answer for hundreds of years, until 1953 when two young men ran into a British pub shouting that they'd discovered the secret of life. If you see the most beautiful girl in the world, you're going to see her again. It was great. The secret was DNA. A microscopic strand of only four chemicals, but capable of such infinite variety, that it carries the blueprint and directs the growth of every living thing on Earth. The genetic revolution was about to begin. For the next 50 years, whole new fields of science and technology burst into being as our understanding of the genetic code buried in DNA grew. It's going to transform everything. Just the bare surface has been... Science will never be the same. There were hopes for healthier lives. That stuff kept me alive and is keeping me alive right now. Promises of an end to inherited disease. I think I've mapped a gene for inherited breast cancer. I don't have to say anything. I'm going to cure cancer. The excitement of discovery. Dizzying. Sometimes when I start to talk about it, I get giddy. Science is like falling in love. I just want to work all the time. I don't want to go home. And the fear of scientists playing God. Contamination. The most dangerous and outrageous experiment. We're worried about things that could fall out of a laboratory such as a Frankenstein. If we don't play God, who will? Even the course of human evolution may soon be ours to control. This is potentially the most important organized scientific effort that the human species has ever mounted. Aspects of society will never be the same again. This is the personal story of the scientists whose struggles and breakthroughs are transforming our biological future. The first generation to live and work in the age of DNA. This was a hard time. I want to go home. Jail plates were contaminated. Most intense hostility. Pestuous discussion. Selfish laughter. It was like running a marathon race that lasts for four years. It's absolutely fascinating. The DNA story begins more than half a century ago. With a group of brilliant, competitive, and temperamental young scientists, all driven to uncover the same elusive mystery. And with Francis Crick and James Watson, two complete unknowns who somehow found what they were all looking for. The secret of life. To appreciate what Watson and Crick did, we have to imagine we're in the 1950s, and all that is known about life is what can be seen through a microscope. Cells divide. They divide and divide again until somehow they eventually form a plant, a penguin, or a person. But how? How do the cells know what to do? Most believed there was a magical life force that would forever elude science. But some had faith in a more rational answer. To tell the story of how the extraordinary breakthrough was made, one has to come to Cambridge University in England. It's a place where many great discoveries have been made during the past 700 years. But if the place has the hallmarks of greatness, Watson and Crick did not. Today, Francis Crick has a house on the edge of the Mojave Desert in California. And he's become a little reclusive when it comes to discussing the early days of DNA. Some say it's because he's ill. They say he finds the whole subject uncomfortable, or maybe he's just busy with his more recent work, studying the chemical nature of dreams. Whatever the reason, he rarely gives interviews. But Jim Watson does. Today he's 74 years old, world famous, and a multimillionaire. But he was just a 22-year-old junior researcher when he set out to explain life in scientific terms. Still, all these years later, one gets a sense of the brash young man who was planning to overthrow the old ways of thinking. You know, if you looked at Cambridge, you know, we were products of God. The statement that life could be understood finally in terms of molecules, people say it was a hypothesis. Francis and I, once united, I just thought religion was wrong. Not necessarily silly, but wrong. There was no God and humans had to make our own rules. Not just obey rules because someone said they came from God. You realize that people thought we were slightly crazy. But we didn't think we were, we thought the other people were dull. Dull or not, the other people at Cambridge didn't hold out much hope of Watson and Crick doing anything at all, let alone finding the secret of life. Watson, this geeky American kid, with his friend Crick, who acted like some dandy English gentleman, a splendid talker who had never quite managed to finish his Ph.D. They were seen as lazy jokers, but they shared the same dream. Like other scientists of the time, they believed that there was some kind of a script or instruction that told cells what to do. The search for this script focused on the chromosomes, right in the middle of every cell. But that was as far as they could see. Still, it was known that chromosomes were made of two discrete ingredients, proteins and DNA. Most scientists expected to find the script in the proteins because they're really complicated and made up of lots of different chemicals. So they distracted the best minds. But Watson and Crick decided to look at the simpler DNA. DNA is composed of only four ingredients. They thought if they could work out how the atoms of these four ingredients were arranged in physical space, they might be able to work out what they did. They had a hunch that the three-dimensional structure of DNA might reveal its function. But while Watson and Crick had never found the structure of anything, 60 miles away in London worked another pair of scientists who had. Rosalind Franklin and Morris Wilkins. Rosalind Franklin is often seen as the heroine of this story. She was Jewish from a wealthy background and had attended the best schools in England. She had chosen to become an expert in taking photographs of things that are too small to see. She's been called the Dark Lady of DNA, as she died without ever getting credit for her part in the discovery. Some say she was betrayed by her colleague at King's College, London. If you go to King's, along a remote corridor, and down these stairs, 50 years later, you'll still find that colleague, Morris Wilkins. And on the walls of his office are clues which hint at what he's been through. During the Second World War, he helped to create the atom bomb. The night it was dropped on Hiroshima, he was at a party celebrating the culmination of that work when a man came up to him and said something that would change his life. It was being Monday when the bomb went off and he said, I call it Black Monday, I always hoped it wouldn't work. I sort of stood there and felt a bit small and then said, yes, I think you're quite right. But it did work, and so we are living kind of in the aftermath of that. Disillusioned with the science of death, he chose the science of life instead. And that's why he decided to look for the structure of DNA. Here is one of the x-ray generators we're using in this work. Here is the x-ray tube. Wilkins' strange contraption is in fact a kind of camera. It's used in a technique called x-ray crystallography. A crystalline form of DNA is placed inside the camera, and when x-rays are fired through it, they scatter onto photographic paper and form a regular pattern. It's a bit like shining a spotlight at a chandelier. Light hits the crystals and then diffracts onto the wall. Now imagine you can't see the chandelier. You can only see the light on the wall. From that you have to guess the shape of the chandelier. And that's what these photographs are. Taken by Morris Wilkins, they were the first clue to the structure of DNA. But his boss realized he was on to something big and decided to bring in an expert, Rosalind Franklin. Suddenly it wasn't just Wilkins taking photographs of DNA. So Watson and Crick were looking for the structure of DNA in Cambridge and Wilkins and Franklin were doing the same in London. But there was someone else lurking out there, someone with a formidable reputation. The brilliant American chemist Linus Pauling. He died years ago, but his son witnessed the dramatic events, and we found him in the middle of Wales, miles from the nearest town. In this house is Peter Pauling. It's very often in science that the times are right, and people have, different people have the same idea. You know, at roughly the same time. And getting in first somehow is important. They were in a race. Peter Pauling knew them all and watched this piece of history unfold. His father, who was about to become a double Nobel Prize winner, certainly had the best credentials. Pa did very few things by accident. He did things... He had a reason for doing things. To Pa, DNA was just a substance like sodium chloride. Linus Pauling looked for the structures of many molecules, and he usually found them too. That's why in the world of 1950s science, he was one of the most recognizable figures. I like to understand the world. I like to learn about new ideas. But I also like very much having new ideas myself, or making discoveries myself. This pleases me immensely. He had a different approach. He was going to guess the structure by building ball and spoke models that looked like a child's tinker toy set. The balls represent the atoms. The spokes determine how far apart the atoms must be from each other according to the laws of physics. Linus Pauling would work at seeing how they fit together. Solving a structure this way was like doing a three-dimensional jigsaw puzzle. So Watson and Crick had a choice. To do the painstaking X-ray work or try their luck building models like Linus Pauling? For them, the choice was simple. To build models. It was only a question when you started to build models. Would you do it after you collected years of experimental data or would you try and build the model with a minimum of data? They went for model building with the minimum of data. Some might say a more leisurely approach, but that was the Cambridge style. And Watson and Crick seemed to be the epitome of that. Wiling away the hours, chatting about the secret of life. People would laugh at us and say, oh, we weren't doing experiments. Just take these long walks at lunch and constantly talking instead of experimentally. Happy days. People see you do no experiments. It was sort of thought, you know, we were parasites. Other people did the work and we got the glory. But the truth was, you know, complicated. In fact, Watson and Crick were asking all the right questions. What was common to all forms of life? What finally seemed to become into all forms of life was there was a script. We'd been thinking it was DNA, but we didn't know the shape of the script. And always the big problem was the copying. Who copied it? There weren't any, you know, little monks inside the cell copying the script. By not getting bogged down in the details of experiments, their minds were free to concentrate on the big ideas. Three teams, three different approaches, and Watson and Crick weren't the favorites. I would say that Watson and Crick were number two. And at that time, I would put my money on this crowd. King's College London should have been the place to find the structure of DNA. King's had cutting-edge equipment and a team of dedicated experts working on the problem. But trouble was brewing. While Morris Wilkins blended into the shadows... Rosalind Franklin was making a big impression on those around her. She was of medium height and had black hair, which she wore straight, just in no particular... arrangement, but she had the most startling dark eyes which showed the intense nature of her personality. Most of the young men who worked with her were half in love with her. One of these young men was Raymond Gosling. At the time, he was a lowly lab assistant working for Rosalind Franklin. Looking back on it, I think I was very privileged to have been there. I only wish I had known at the time that it was that important. I might have remembered more, worked harder, and who knows? I might have tried building a few models secretly. Model building was in the air, but her view was you could build models all day, but how did you prove which one was right? On the other hand, if you made the measurements... you did all the corrective geometry, and you put them into the equations, you would let the data speak for itself. And out of that would come a definitive structure. But there was a problem. Wilkins was under the impression that DNA was his project. Their boss had told Franklin it was hers. No mention was ever made of the fact that Wilkins was the overarching person concerned in the lab. She certainly felt she was coming in, she was taking over that defraction work. So at opposite ends of the corridor, Morris Wilkins and Rosalind Franklin worked on DNA. Occasionally, they would announce their results to the department. One afternoon in November 1951, Franklin was to reveal her latest DNA data to a select group of King's College scientists and one outsider. This is where I came in, early November 1951, to hear Rosalind Franklin talk about her newest results on DNA. And I was terribly keen to know. what she'd done because I wanted to build a model. I thought I would learn possibly something about the structure. There were probably 30 people in the room and I slipped in. It was inside us, like a spy. And Rosalind was seemingly much in control. I generally never took notes. My memory was good. Having taken in as much as he could of the X-ray data, Watson rushed back to Cambridge to tell Crick what he'd heard. For the next two weeks they worked on a model and on November 28th, 1951, Watson and Crick announced that they had found the structure of DNA. Francis rang me up and said we've made a model. Come have a look. So I went to the others and we all went up. It was a pretty ugly structure. Francis liked that, I don't know. You know, he called off the people at King's and said, we've done something clever, and I was a bit worried. Feeling apprehensive, the King's team left for Cambridge. Rosalind Franklin took one look at the model and... She laughed at them. Much to their discomfiture, I think, and said, oh, look, you've got it inside out. Watson's memory had let him down over how much water was absorbed in the DNA crystals. The water... ...content is vital to the structure, so their model was a complete disaster. Rosalind was tickled pink. She was right. The building of a model of a crystal structure was a waste of time until you'd let diffraction speak for itself. And that was hard work. I don't know, I mean, one might say, well, why not? I mean, it's an exploration. to make a model. I mean, make a model, and if you make a bit of a fool of yourself in the process, why worry? You might be lucky. The most strange thing about science is how stupid people can be so much of the time. And so Frances and I were really stupid. Worse than that, they'd incurred the wrath of the London team's boss, Sir John Randall, who called up Watson and Crick's boss, Sir Lawrence Bragg, to complain about their behavior. And Bragg was furious. In those days, it wasn't gentlemanly to have knowledge of somebody's current unpublished work and to make use of that, working on the same problem. It was rather like having an affair with his wife. I mean, it happened, but you didn't really take much credit in doing it. Watson and Crick were kicked off the case. And even their model-building equipment was sent to King's. Watson and Crick were officially barred from the race. The way should have been open for the King's College team, but Morris and Rosalind didn't get along. With the stakes so high, why couldn't they just resolve their differences? Morris was so shy that when he was talking to you and he didn't know you, he habitually talked at an angle. So you might find that you were addressing the back of his head. I think scientists in particular tend to be rather... Well, I don't know, sort of bottled up with serious thoughts and wonderful theories that... and the secret of life or something. He would slide... into a room and mumble something and be very diffident about it. He was never going to come in and say, well, I'm glad you've joined my team, and say, this is the way we do it, spit, spot, bang, which had he done. would have cleared the air. You know, he wasn't able to talk to her. He should have made, as the more senior, made the effort to bring her into the camp and that he sulked in his tent far too often. I think he knows this and it's haunted him. Today, Rosalind Franklin is an icon. Outside a dormitory for female students that bears her name stands her statue. The only thing that survives, that gives a sense of what she was like, are her letters. In one that she wrote to her religious father, she argues for the importance of science in understanding the world. Science for me gives a partial explanation of life. Insofar as it goes, it's based on fact, experience and experiment. Your theories are those which you and many other people find easiest and pleasantest to believe. But as far as I can see, they have no foundation, other than that they lead to a pleasant view of life and an exaggerated view of our own importance. Anyone able to believe in all that religion implies obviously must have such faith. But I maintain that faith in this world is perfectly possible without faith in another world. The picture, to me, seemed to say something about Rosalind. Rosalind has sometimes seemed a bit sort of heavy in appearance. I mean, not always, but sometimes. and I thought, well, it would have been nice if she'd been able to sort of trip around on her toes and look pretty and cheerful. But I think it was very sad because we had thought we might be all able to join together, you see, in the scientific work. It's... it had two sides to the whole thing. Back in Cambridge, Watson was down in the dumps. Banned from working on DNA, his dream of showing that it was the secret of life was slipping away. But Crick had some good news. Someone was coming to dinner in Cambridge who could help them. Erwin Chargaff had never intended to help Watson and Crick. Even at 96 years old, he's still bitter about what had happened. Chargaff was an expert in the chemistry of DNA. Over dinner, Watson and Crick tried to plumb him for information. They were fishing, really. But that, I get the impression, they did all the time. I think Watson really was a fisherman. I mean, he sort of brought the news to Crick. Crick was apparently the man who had the ideas. Well, I think we didn't like him because he... Sort of didn't, you know, warm up to our saying, you know, you could solve the structure of DNA by model building, you know. They both showed an extreme contempt for chemistry. That was what struck me. They were more like children in their behavior. He was just a born enemy. Despite his extreme dislike for them, he did explain his Chargaff rules that state the relative amounts of the four basic ingredients of DNA. By comparing samples from three different species, he discovered a strange correlation. No matter what the life form, the amount of A equaled the amount of T, and the amount of C equaled the amount of G. This suggested the chemicals somehow went together in pairs. For Chargaff, this was an interesting correlation, but for Watson and Crick, it was the first clue to the structure. I think DNA to him was an objective whose time had not yet come. Oh yes, good, yes, there's the unichem. Excellent. On this desk is the original equipment that helped reveal the structure of DNA. So this is the first camera, this is the first DNA. It's worth a fortune today. I mean, putting them in a frame like that, they look much better than just sort of lying on a table, don't they? The X-rays go in here. Photographic film is put on the inside here. Then that is... It is put down around the DNA. Like everything with Morris, there's more to it than meets the eye. Now, you want to say something about these? These are small-scale models. Morris had also wanted to build models based on the X-ray data, but Roslund had all the best DNA samples, and they weren't talking. No one else at King's really had the imagination to help him. At King's, if anybody did perhaps see the overarching picture, Wilkins did, because he often said, you know, we should all wake up, we should all try a number of different things instead of plodding along trying to solve the X-ray diffraction pattern, because we are in a race. It is an important problem. And there are other people. I mean, there was this bogeyman sitting in America called Linus Pauling who already had a problem. he had two Nobel Prizes, not one, and he was thinking about it. By now, Linus Pauling had turned his full attention to DNA. Suspiciously, this coincided with a certain young playboy travelling from California to England to work in Watson and Crick's office. In those days, Linus had a son who was about the same age as Watson, and knew Watson. And Powling came across, came to our lab, and he went and stayed with Watson and Crick. And I think he put the fear of God into them, that Dad was thinking about this. I had the feeling, what was he doing in the laboratory of his father's big... I was accused of being a double agent, but I don't accept that because I'd write to Pa and just say what I'm doing, and he'd write back, you know, what he was interested in. And Pa was not only writing back to Peter, he was busy writing other letters, too. I wrote to Wilkins at King's College asking if I could have... prints of the photographs that he had obtained, but my effort was not successful. Back at King's College, London, they had made an astonishing discovery. The scattered dots of light that suggest how the atoms of DNA might be arranged were coming into sharp focus. Rosalind Franklin had taken this, the clearest picture yet. The X pattern indicated that DNA ingredients are arranged in a spiral, what scientists call a helix. But Rosalind Franklin wasn't letting anyone else see it. So Linus Pauling never got his hands on this X pattern. Could he have come up with the right answer without seeing the king's data? Of course, I hoped he couldn't. It wasn't until, you know, about the last day of January that Peter came in after lunch and... I had a manuscript. I had a letter from my father in December of 52 saying he had proposed a structure for DNA. So I told the boys. Oh, they rushed over. My stomach sank and I was scared to death. What was going to be in it? I opened it and read it and they discovered that it was wrong. What if... What if... I didn't align us. Pauling's model not only didn't fit the data, it also failed to explain anything about what DNA did. He had blundered by trying to get the structure with too little information. There wasn't any envy good as to whether Linus was right or wrong. He said Linus was wrong. So we were both pleased and a bit scared because... Maybe someone at Caltech's group would tell Linus this is chemical nonsense. Little do we know that no one at Caltech really had the courage to tell Linus it was wrong. Linus was like the Pope. Linus wasn't used to people saying he was wrong. So I've had a very fortunate life. I thought the people at King's should be relieved. So without being asked, I said, well, I'll just take the manuscript down to King's. It's just bubbling over with the fact that we have another chance. Polling it got us wrong and we should go into action fast. Watson was still not even supposed to be working on DNA, but he took the risk of going to King's again. I didn't have that much time. I wanted something to happen now. So I went down and looked for Morris and didn't spot him, and someone told me where Rosalind's office was. So I went toward it and walked in. She wasn't there. I wasn't trying to read the letters on her desk or anything like that, but obviously I was looking around and she came in. Someone had told her that I was looking for her. She had a very negative reaction to me and fury was rising. She didn't think I should be there. So I got out of the room as fast as possible, and then Morris Wilkins had heard I was around, and there he was. And I said, oh, I thought she was going to hit me. And he said, oh, I thought she was going to do that to me once. And so... So I went to, he took me to his office and opened a drawer and took out a photo, and there it was, the cross, which I had never seen, and which they had basically weren't talking about. It showed this sort of X type of... ...oxo type of cross pattern which was an indication of a helix. I was at a big high. I mean, it was the most beautiful photograph. You know, it's as if you've seen the most beautiful girl in the world and you're going to see her again. You know, it was great. If I got excited about the results, I'd head to pass them on. I don't know, I think it... I didn't feel there was any sort of bombshell in this. Well, the picture kept sort of racing through my brain, and I wanted to be sure I had it right, so I wrote it down. It was just a super reflection of 3.4 angstroms, and boom, boom, boom. No one could look at it and say it's not a helix. And the reason that Watson realized that it was a helix? So as you get across in the diffraction pattern... Well, it just so happened that Crick knew this bit of X-ray diffraction theory and had told Watson that an X indicated a helix. This wasn't his specialty, but Crick's mind was able to absorb ideas from many disciplines, and now it was paying off. You know, I felt, you know, maybe we'll get the answer, you know. Until then, I didn't feel we were close. I felt, that picture means we're close. Wilkins undoubtedly, and I think... If you ask him, he will say that he feels that he did. If there were any cats to be let out of any bags, he'd done it. Well, that's perfectly true, but I think this science isn't supposed to be kept in bags, no more than cats. I mean, I don't know what he means, but I don't like it as a scientist, sort of working away and sort of saying, oh, no, tell the other scientists or something. I think it's the way to be working. Science ought to be an open activity, so you can work as a community. It would have been impossible not to have bottles after seeing that picture. Spring came early to Cambridge in 1953. Watson and Crick were given official permission to return to their work on DNA. And by now they had managed to acquire all the information they needed. Chargaff's data suggested that the four chemicals in DNA might go together in pairs. It was time to see how these pairs would fit together, to discover whether the shape of DNA would tell them what it did. The Cavendish shop was to build us some tin models, and that took too long. And, you know, finally in desperation, I made some other cardboard. I sort of finished the job on Friday and didn't get back into the Cavendish probably until much before 9.30 on Saturday morning. So I came in the morning and I began moving them around. And I wanted an arrangement, you know, where I had a big and a small. So, how did you do it? Somehow you had to form link bonds. So here's A and here's T. And I wanted this hydrogen. I point directly at this nitrogen, so I had something like this. Oh! So then I went to the pair, and I wanted this nitrogen to point to this one. I went like this. Whoa! They look the same. So we had two base pairs identical in shape. And, boy, I could hardly believe it. Franklin's photo suggested these pairs had to fit into some kind of helix. And when they saw that the pairs were the same shape, they realized that they could stack on top of each other. You can put one right on top of the other. And they realized that to form a helix, they not only stacked on top of each other, but they also twisted around, like the steps in a spiral staircase, onwards and upwards. In their minds, the double helix structure of DNA emerged. So you can have a small one, a big one, a small one, any sequence. We knew we could just, you know, even if we go up to the ceiling, we were building a tiny fraction of a molecule. 100 million of these base tests in one molecule. So unbelievably all united by this either AT or TA, GC, CG, all fitting into this wonderful symmetry which we saw the morning of February 28, 1953. The double helix was a structure that revealed far more about the way life works than they could ever have dreamed of. They'd been looking for something that could divide, just like cells do, and it was easy to see how a double helix could unwind and form two more double helixes. They'd been trying to find out if DNA was the script or instructions for all living things. They realized that the millions of G's, A's, T's, and C's must be written in some kind of code, the script of life. And they even saw how the script could be copied exactly as the As the double helix unwinds, each of the letters forms a new pair. And because A always goes with T and G always goes with C, the resulting two pieces of DNA are exact copies of the original, enabling the script to be passed from cell to cell and ultimately from generation to generation. It was clear now, DNA was the molecule that controlled all living things. Watson and Crick ran straight to the pub, where their news was going to be hard to believe. It was hard to contain the fact that, you know, maybe we had a gigantic breakthrough. We'd done something really important. We had discovered the secret of life. You could say that day was the beginning of the new genetics. They had the idea, but now they wanted to check that it was right. They set about building a tin model as quickly as they could, cross-checking their coordinates with the King's data. It all fit. Then we had to tell the people at King's, and... We were a bit apprehensive because we didn't want to say, well, we've beaten you. You have to remember that I'd been up before and seen the model that was wrong. And that gave us a buzz and a high. And then you go up there and you see this thing. It looked right when you saw it. It was so brilliantly, elegantly simple. I thought, oh, my God, we got scooped. Because I really thought we were going to come up with something like that ourselves. It was terrible, you know, for Morris. I said that the double helix was somewhat similar to... a young baby standing there all alive and saying, I don't care what you say or what you think. I know I am right. Rosalind would have been appalled to learn that they had taken quite so much detail of her current work and put it into their model. Arguing whether we behave right or wrong or we're good or bad guys depends on your set of values and the facts you have. The extent to which Rosalind Franklin was badly treated is still debated to this day. She's an enigmatic character who kept her distance from the other people in this story. She spent her time working alone in her lab. People have wondered how close she came to finding the structure of DNA. The only way to know is to visit this archive in Cambridge, where her notebooks are kept. Her notes suggest that she nearly got there. In one of her final entries, she's thinking in terms of a two-chain or double helix. But that's as far as she got. She died five years later in 1958, without ever being told the extent to which Watson and Crick had used her data. And when the Nobel Prizes were awarded for the discovery, they went to Watson and Crick and Morris Wilkins. She didn't get one because Nobel Prizes can't be awarded posthumously. People who knew her say that... what she cared about most was that her work moved science forward. It was one of the few things she had in common with Morris Wilkins. Without their work, Watson and Crick could not have built this model. And the model was just the beginning. Over the next two days, she was able to build a model For decades, scientists delved into the molecular world of DNA and discovered how it actually controls life. The genius who did more than anyone to unravel its mysteries was Francis Crick. Today, he's at the Salk Institute in California. In one interview that has never before been broadcast, Crick did talk about what for him came after the double helix. It involves thinking beyond what he calls the narrow limits of normal human experience. Now, when you want to understand the world, you have to go beyond those narrow limits, both up and down, both in space and time. And then you find that there's a uniformity and extraordinary things happening which you'd no idea of just looking at the world. And this is the fascination of science really, I think, to uncover so much which is not apparent just in everyday life. Today we have a way to see the molecular world. This is what DNA looks like when you put the very latest scientific data into a computer simulator. It's a long way from Tinker Toy models. What is apparent is that everything in the molecular world is more strange and sophisticated than anyone had thought. Biological systems are the result of evolution, and they produce very complicated things. Now, the reason that DNA looks so beautiful and simple is it goes right back to near the origins of life, where things had to be simple. But if you actually look at the actual process of DNA replication, it isn't at all the way that we used to describe it. All sorts of funny things happen. You have to have proteins which will unwind the helix and nick it and then join it together again. You get an enormously, very complicated apparatus, which one might say molecular gadgetry, which actually does the job. This is the incredible way DNA copies itself. But DNA is much more than a self-replicating molecule. It is the essence of life, carrying from generation to generation the information needed to make all living things, written in the DNA language of A's, C's, G's, and T's. Francis Crick wanted to crack this genetic code to understand the complete process of life. To achieve this would involve deconstructing the gadgets of the molecular world. He started by working backwards. What's sometimes called reverse engineering. It happens in the commercial world when one firm produces a gadget and another firm buys it and tries to take it to pieces and find how it works. That's called reverse engineering. But in our case, it's reverse engineering in what you might call a foreign culture. As a result of that process, today it's possible to see how DNA makes living things. How DNA's code is turned into flesh and blood. And for scientists, life is no longer a mystery. The blue molecule racing down the DNA unzips the double helix and copies one of the two strands. This copy is then released for the next stage of the process. process. The yellow copy feeds into another machine which deciphers the code and orders up the right components one unit at a time from the surrounding chemical soup. The product of this machine is protein. This could be a thousandth of an eyebrow. The same process could make a tiger's claw or part of the wings of a dove. It's the same for all life. What is made is all down to the DNA, the specific order of the chemical code. And today, these machines can read that DNA code. How a person is made is being revealed. How our brains are built is being explained. In the G's, A's, T's and C's, they're beginning to read differences in our characters and personality. The genetics of human nature is slowly unfolding. Even our story can be seen in this way. The fate of our characters determined by their... individual natures. I thought the problem would last me my lifetime. I had no idea it would be solved within 20 years. You see, I was, I mean it was embarrassing almost to got to the stage where instead of this problem lasting for one's life, one had to look around for another problem. Now Francis Crick is trying to find out how the brain works. He's always only been interested in making new discoveries. Jim Watson runs Cold Spring Harbor Laboratories on Long Island in New York. He employs 800 people and is still at the cutting edge of DNA science. He had a house built on the grounds and erected an enormous sculpture of the double helix. He travels the world giving lectures and arguing for the benefits of genetic engineering. Our people say, well, we're playing God. You know, I have a straightforward answer. If we don't play God, who will? And Morris Wilkins couldn't be more different. Having worked on the atomic bomb, he chose to study DNA because he thought it wouldn't be controversial. Today, as the newspapers talk of creating designer babies and the birth of human clones, he lectures at King's College London about the social responsibility of science. He hopes the human race will use this knowledge wisely.

and in sickness. Scientists had searched for the answer for hundreds of years, until 1953 when two young men ran into a British pub shouting that they'd discovered the secret of life. If you see the most beautiful girl in the world, you're going to see her again. It was great. The secret was DNA.

A microscopic strand of only four chemicals, but capable of such infinite variety, that it carries the blueprint and directs the growth of every living thing on Earth. The genetic revolution was about to begin. For the next 50 years, whole new fields of science and technology burst into being as our understanding of the genetic code buried in DNA grew.

It's going to transform everything. Just the bare surface has been... Science will never be the same. There were hopes for healthier lives.

That stuff kept me alive and is keeping me alive right now. Promises of an end to inherited disease. I think I've mapped a gene for inherited breast cancer.

I don't have to say anything. I'm going to cure cancer. The excitement of discovery. Dizzying. Sometimes when I start to talk about it, I get giddy.

Science is like falling in love. I just want to work all the time. I don't want to go home. And the fear of scientists playing God.

Contamination. The most dangerous and outrageous experiment. We're worried about things that could fall out of a laboratory such as a Frankenstein.

If we don't play God, who will? Even the course of human evolution may soon be ours to control. This is potentially the most important organized scientific effort that the human species has ever mounted. Aspects of society will never be the same again. This is the personal story of the scientists whose struggles and breakthroughs are transforming our biological future.

The first generation to live and work in the age of DNA. This was a hard time. I want to go home.

Jail plates were contaminated. Most intense hostility. Pestuous discussion.

Selfish laughter. It was like running a marathon race that lasts for four years. It's absolutely fascinating. The DNA story begins more than half a century ago. With a group of brilliant, competitive, and temperamental young scientists, all driven to uncover the same elusive mystery.

And with Francis Crick and James Watson, two complete unknowns who somehow found what they were all looking for. The secret of life. To appreciate what Watson and Crick did, we have to imagine we're in the 1950s, and all that is known about life is what can be seen through a microscope. Cells divide. They divide and divide again until somehow they eventually form a plant, a penguin, or a person.

But how? How do the cells know what to do? Most believed there was a magical life force that would forever elude science.

But some had faith in a more rational answer. To tell the story of how the extraordinary breakthrough was made, one has to come to Cambridge University in England. It's a place where many great discoveries have been made during the past 700 years. But if the place has the hallmarks of greatness, Watson and Crick did not. Today, Francis Crick has a house on the edge of the Mojave Desert in California.

And he's become a little reclusive when it comes to discussing the early days of DNA. Some say it's because he's ill. They say he finds the whole subject uncomfortable, or maybe he's just busy with his more recent work, studying the chemical nature of dreams.

Whatever the reason, he rarely gives interviews. But Jim Watson does. Today he's 74 years old, world famous, and a multimillionaire.

But he was just a 22-year-old junior researcher when he set out to explain life in scientific terms. Still, all these years later, one gets a sense of the brash young man who was planning to overthrow the old ways of thinking. You know, if you looked at Cambridge, you know, we were products of God.

The statement that life could be understood finally in terms of molecules, people say it was a hypothesis. Francis and I, once united, I just thought religion was wrong. Not necessarily silly, but wrong.

There was no God and humans had to make our own rules. Not just obey rules because someone said they came from God. You realize that people thought we were slightly crazy.

But we didn't think we were, we thought the other people were dull. Dull or not, the other people at Cambridge didn't hold out much hope of Watson and Crick doing anything at all, let alone finding the secret of life. Watson, this geeky American kid, with his friend Crick, who acted like some dandy English gentleman, a splendid talker who had never quite managed to finish his Ph.D. They were seen as lazy jokers, but they shared the same dream.

Like other scientists of the time, they believed that there was some kind of a script or instruction that told cells what to do. The search for this script focused on the chromosomes, right in the middle of every cell. But that was as far as they could see. Still, it was known that chromosomes were made of two discrete ingredients, proteins and DNA. Most scientists expected to find the script in the proteins because they're really complicated and made up of lots of different chemicals.

So they distracted the best minds. But Watson and Crick decided to look at the simpler DNA. DNA is composed of only four ingredients. They thought if they could work out how the atoms of these four ingredients were arranged in physical space, they might be able to work out what they did.

They had a hunch that the three-dimensional structure of DNA might reveal its function. But while Watson and Crick had never found the structure of anything, 60 miles away in London worked another pair of scientists who had. Rosalind Franklin and Morris Wilkins. Rosalind Franklin is often seen as the heroine of this story.

She was Jewish from a wealthy background and had attended the best schools in England. She had chosen to become an expert in taking photographs of things that are too small to see. She's been called the Dark Lady of DNA, as she died without ever getting credit for her part in the discovery. Some say she was betrayed by her colleague at King's College, London. If you go to King's, along a remote corridor, and down these stairs, 50 years later, you'll still find that colleague, Morris Wilkins.

And on the walls of his office are clues which hint at what he's been through. During the Second World War, he helped to create the atom bomb. The night it was dropped on Hiroshima, he was at a party celebrating the culmination of that work when a man came up to him and said something that would change his life.

It was being Monday when the bomb went off and he said, I call it Black Monday, I always hoped it wouldn't work. I sort of stood there and felt a bit small and then said, yes, I think you're quite right. But it did work, and so we are living kind of in the aftermath of that.

Disillusioned with the science of death, he chose the science of life instead. And that's why he decided to look for the structure of DNA. Here is one of the x-ray generators we're using in this work. Here is the x-ray tube. Wilkins' strange contraption is in fact a kind of camera.

It's used in a technique called x-ray crystallography. A crystalline form of DNA is placed inside the camera, and when x-rays are fired through it, they scatter onto photographic paper and form a regular pattern. It's a bit like shining a spotlight at a chandelier.

Light hits the crystals and then diffracts onto the wall. Now imagine you can't see the chandelier. You can only see the light on the wall. From that you have to guess the shape of the chandelier. And that's what these photographs are.

Taken by Morris Wilkins, they were the first clue to the structure of DNA. But his boss realized he was on to something big and decided to bring in an expert, Rosalind Franklin. Suddenly it wasn't just Wilkins taking photographs of DNA.

So Watson and Crick were looking for the structure of DNA in Cambridge and Wilkins and Franklin were doing the same in London. But there was someone else lurking out there, someone with a formidable reputation. The brilliant American chemist Linus Pauling.

He died years ago, but his son witnessed the dramatic events, and we found him in the middle of Wales, miles from the nearest town. In this house is Peter Pauling. It's very often in science that the times are right, and people have, different people have the same idea. You know, at roughly the same time. And getting in first somehow is important.

They were in a race. Peter Pauling knew them all and watched this piece of history unfold. His father, who was about to become a double Nobel Prize winner, certainly had the best credentials.

Pa did very few things by accident. He did things... He had a reason for doing things.

To Pa, DNA was just a substance like sodium chloride. Linus Pauling looked for the structures of many molecules, and he usually found them too. That's why in the world of 1950s science, he was one of the most recognizable figures. I like to understand the world. I like to learn about new ideas.

But I also like very much having new ideas myself, or making discoveries myself. This pleases me immensely. He had a different approach.

He was going to guess the structure by building ball and spoke models that looked like a child's tinker toy set. The balls represent the atoms. The spokes determine how far apart the atoms must be from each other according to the laws of physics. Linus Pauling would work at seeing how they fit together.

Solving a structure this way was like doing a three-dimensional jigsaw puzzle. So Watson and Crick had a choice. To do the painstaking X-ray work or try their luck building models like Linus Pauling? For them, the choice was simple.

To build models. It was only a question when you started to build models. Would you do it after you collected years of experimental data or would you try and build the model with a minimum of data?

They went for model building with the minimum of data. Some might say a more leisurely approach, but that was the Cambridge style. And Watson and Crick seemed to be the epitome of that.

Wiling away the hours, chatting about the secret of life. People would laugh at us and say, oh, we weren't doing experiments. Just take these long walks at lunch and constantly talking instead of experimentally.

Happy days. People see you do no experiments. It was sort of thought, you know, we were parasites.

Other people did the work and we got the glory. But the truth was, you know, complicated. In fact, Watson and Crick were asking all the right questions.

What was common to all forms of life? What finally seemed to become into all forms of life was there was a script. We'd been thinking it was DNA, but we didn't know the shape of the script. And always the big problem was the copying.

Who copied it? There weren't any, you know, little monks inside the cell copying the script. By not getting bogged down in the details of experiments, their minds were free to concentrate on the big ideas.

Three teams, three different approaches, and Watson and Crick weren't the favorites. I would say that Watson and Crick were number two. And at that time, I would put my money on this crowd. King's College London should have been the place to find the structure of DNA.

King's had cutting-edge equipment and a team of dedicated experts working on the problem. But trouble was brewing. While Morris Wilkins blended into the shadows... Rosalind Franklin was making a big impression on those around her. She was of medium height and had black hair, which she wore straight, just in no particular...

arrangement, but she had the most startling dark eyes which showed the intense nature of her personality. Most of the young men who worked with her were half in love with her. One of these young men was Raymond Gosling.

At the time, he was a lowly lab assistant working for Rosalind Franklin. Looking back on it, I think I was very privileged to have been there. I only wish I had known at the time that it was that important. I might have remembered more, worked harder, and who knows? I might have tried building a few models secretly.

Model building was in the air, but her view was you could build models all day, but how did you prove which one was right? On the other hand, if you made the measurements... you did all the corrective geometry, and you put them into the equations, you would let the data speak for itself. And out of that would come a definitive structure. But there was a problem.

Wilkins was under the impression that DNA was his project. Their boss had told Franklin it was hers. No mention was ever made of the fact that Wilkins was the overarching person concerned in the lab.

She certainly felt she was coming in, she was taking over that defraction work. So at opposite ends of the corridor, Morris Wilkins and Rosalind Franklin worked on DNA. Occasionally, they would announce their results to the department.

One afternoon in November 1951, Franklin was to reveal her latest DNA data to a select group of King's College scientists and one outsider. This is where I came in, early November 1951, to hear Rosalind Franklin talk about her newest results on DNA. And I was terribly keen to know. what she'd done because I wanted to build a model.

I thought I would learn possibly something about the structure. There were probably 30 people in the room and I slipped in. It was inside us, like a spy. And Rosalind was seemingly much in control. I generally never took notes.

My memory was good. Having taken in as much as he could of the X-ray data, Watson rushed back to Cambridge to tell Crick what he'd heard. For the next two weeks they worked on a model and on November 28th, 1951, Watson and Crick announced that they had found the structure of DNA.

Francis rang me up and said we've made a model. Come have a look. So I went to the others and we all went up.

It was a pretty ugly structure. Francis liked that, I don't know. You know, he called off the people at King's and said, we've done something clever, and I was a bit worried.

Feeling apprehensive, the King's team left for Cambridge. Rosalind Franklin took one look at the model and... She laughed at them. Much to their discomfiture, I think, and said, oh, look, you've got it inside out. Watson's memory had let him down over how much water was absorbed in the DNA crystals.

The water... ...content is vital to the structure, so their model was a complete disaster. Rosalind was tickled pink. She was right. The building of a model of a crystal structure was a waste of time until you'd let diffraction speak for itself.

And that was hard work. I don't know, I mean, one might say, well, why not? I mean, it's an exploration. to make a model. I mean, make a model, and if you make a bit of a fool of yourself in the process, why worry?

You might be lucky. The most strange thing about science is how stupid people can be so much of the time. And so Frances and I were really stupid.

Worse than that, they'd incurred the wrath of the London team's boss, Sir John Randall, who called up Watson and Crick's boss, Sir Lawrence Bragg, to complain about their behavior. And Bragg was furious. In those days, it wasn't gentlemanly to have knowledge of somebody's current unpublished work and to make use of that, working on the same problem.

It was rather like having an affair with his wife. I mean, it happened, but you didn't really take much credit in doing it. Watson and Crick were kicked off the case.

And even their model-building equipment was sent to King's. Watson and Crick were officially barred from the race. The way should have been open for the King's College team, but Morris and Rosalind didn't get along. With the stakes so high, why couldn't they just resolve their differences? Morris was so shy that when he was talking to you and he didn't know you, he habitually talked at an angle.

So you might find that you were addressing the back of his head. I think scientists in particular tend to be rather... Well, I don't know, sort of bottled up with serious thoughts and wonderful theories that...

and the secret of life or something. He would slide... into a room and mumble something and be very diffident about it. He was never going to come in and say, well, I'm glad you've joined my team, and say, this is the way we do it, spit, spot, bang, which had he done.

would have cleared the air. You know, he wasn't able to talk to her. He should have made, as the more senior, made the effort to bring her into the camp and that he sulked in his tent far too often.

I think he knows this and it's haunted him. Today, Rosalind Franklin is an icon. Outside a dormitory for female students that bears her name stands her statue.

The only thing that survives, that gives a sense of what she was like, are her letters. In one that she wrote to her religious father, she argues for the importance of science in understanding the world. Science for me gives a partial explanation of life. Insofar as it goes, it's based on fact, experience and experiment. Your theories are those which you and many other people find easiest and pleasantest to believe.

But as far as I can see, they have no foundation, other than that they lead to a pleasant view of life and an exaggerated view of our own importance. Anyone able to believe in all that religion implies obviously must have such faith. But I maintain that faith in this world is perfectly possible without faith in another world.

The picture, to me, seemed to say something about Rosalind. Rosalind has sometimes seemed a bit sort of heavy in appearance. I mean, not always, but sometimes. and I thought, well, it would have been nice if she'd been able to sort of trip around on her toes and look pretty and cheerful. But I think it was very sad because we had thought we might be all able to join together, you see, in the scientific work.

It's... it had two sides to the whole thing. Back in Cambridge, Watson was down in the dumps.

Banned from working on DNA, his dream of showing that it was the secret of life was slipping away. But Crick had some good news. Someone was coming to dinner in Cambridge who could help them. Erwin Chargaff had never intended to help Watson and Crick. Even at 96 years old, he's still bitter about what had happened.

Chargaff was an expert in the chemistry of DNA. Over dinner, Watson and Crick tried to plumb him for information. They were fishing, really.

But that, I get the impression, they did all the time. I think Watson really was a fisherman. I mean, he sort of brought the news to Crick. Crick was apparently the man who had the ideas. Well, I think we didn't like him because he...

Sort of didn't, you know, warm up to our saying, you know, you could solve the structure of DNA by model building, you know. They both showed an extreme contempt for chemistry. That was what struck me.

They were more like children in their behavior. He was just a born enemy. Despite his extreme dislike for them, he did explain his Chargaff rules that state the relative amounts of the four basic ingredients of DNA. By comparing samples from three different species, he discovered a strange correlation. No matter what the life form, the amount of A equaled the amount of T, and the amount of C equaled the amount of G.

This suggested the chemicals somehow went together in pairs. For Chargaff, this was an interesting correlation, but for Watson and Crick, it was the first clue to the structure. I think DNA to him was an objective whose time had not yet come.

Oh yes, good, yes, there's the unichem. Excellent. On this desk is the original equipment that helped reveal the structure of DNA. So this is the first camera, this is the first DNA.

It's worth a fortune today. I mean, putting them in a frame like that, they look much better than just sort of lying on a table, don't they? The X-rays go in here.

Photographic film is put on the inside here. Then that is... It is put down around the DNA. Like everything with Morris, there's more to it than meets the eye.

Now, you want to say something about these? These are small-scale models. Morris had also wanted to build models based on the X-ray data, but Roslund had all the best DNA samples, and they weren't talking.

No one else at King's really had the imagination to help him. At King's, if anybody did perhaps see the overarching picture, Wilkins did, because he often said, you know, we should all wake up, we should all try a number of different things instead of plodding along trying to solve the X-ray diffraction pattern, because we are in a race. It is an important problem. And there are other people.

I mean, there was this bogeyman sitting in America called Linus Pauling who already had a problem. he had two Nobel Prizes, not one, and he was thinking about it. By now, Linus Pauling had turned his full attention to DNA. Suspiciously, this coincided with a certain young playboy travelling from California to England to work in Watson and Crick's office. In those days, Linus had a son who was about the same age as Watson, and knew Watson.

And Powling came across, came to our lab, and he went and stayed with Watson and Crick. And I think he put the fear of God into them, that Dad was thinking about this. I had the feeling, what was he doing in the laboratory of his father's big...

I was accused of being a double agent, but I don't accept that because I'd write to Pa and just say what I'm doing, and he'd write back, you know, what he was interested in. And Pa was not only writing back to Peter, he was busy writing other letters, too. I wrote to Wilkins at King's College asking if I could have... prints of the photographs that he had obtained, but my effort was not successful. Back at King's College, London, they had made an astonishing discovery.

The scattered dots of light that suggest how the atoms of DNA might be arranged were coming into sharp focus. Rosalind Franklin had taken this, the clearest picture yet. The X pattern indicated that DNA ingredients are arranged in a spiral, what scientists call a helix. But Rosalind Franklin wasn't letting anyone else see it.

So Linus Pauling never got his hands on this X pattern. Could he have come up with the right answer without seeing the king's data? Of course, I hoped he couldn't. It wasn't until, you know, about the last day of January that Peter came in after lunch and... I had a manuscript.

I had a letter from my father in December of 52 saying he had proposed a structure for DNA. So I told the boys. Oh, they rushed over.

My stomach sank and I was scared to death. What was going to be in it? I opened it and read it and they discovered that it was wrong. What if... What if...

I didn't align us. Pauling's model not only didn't fit the data, it also failed to explain anything about what DNA did. He had blundered by trying to get the structure with too little information. There wasn't any envy good as to whether Linus was right or wrong. He said Linus was wrong.

So we were both pleased and a bit scared because... Maybe someone at Caltech's group would tell Linus this is chemical nonsense. Little do we know that no one at Caltech really had the courage to tell Linus it was wrong.

Linus was like the Pope. Linus wasn't used to people saying he was wrong. So I've had a very fortunate life. I thought the people at King's should be relieved.

So without being asked, I said, well, I'll just take the manuscript down to King's. It's just bubbling over with the fact that we have another chance. Polling it got us wrong and we should go into action fast.

Watson was still not even supposed to be working on DNA, but he took the risk of going to King's again. I didn't have that much time. I wanted something to happen now.

So I went down and looked for Morris and didn't spot him, and someone told me where Rosalind's office was. So I went toward it and walked in. She wasn't there.

I wasn't trying to read the letters on her desk or anything like that, but obviously I was looking around and she came in. Someone had told her that I was looking for her. She had a very negative reaction to me and fury was rising.

She didn't think I should be there. So I got out of the room as fast as possible, and then Morris Wilkins had heard I was around, and there he was. And I said, oh, I thought she was going to hit me.

And he said, oh, I thought she was going to do that to me once. And so... So I went to, he took me to his office and opened a drawer and took out a photo, and there it was, the cross, which I had never seen, and which they had basically weren't talking about.

It showed this sort of X type of... ...oxo type of cross pattern which was an indication of a helix. I was at a big high.

I mean, it was the most beautiful photograph. You know, it's as if you've seen the most beautiful girl in the world and you're going to see her again. You know, it was great. If I got excited about the results, I'd head to pass them on.

I don't know, I think it... I didn't feel there was any sort of bombshell in this. Well, the picture kept sort of racing through my brain, and I wanted to be sure I had it right, so I wrote it down. It was just a super reflection of 3.4 angstroms, and boom, boom, boom. No one could look at it and say it's not a helix.

And the reason that Watson realized that it was a helix? So as you get across in the diffraction pattern... Well, it just so happened that Crick knew this bit of X-ray diffraction theory and had told Watson that an X indicated a helix.

This wasn't his specialty, but Crick's mind was able to absorb ideas from many disciplines, and now it was paying off. You know, I felt, you know, maybe we'll get the answer, you know. Until then, I didn't feel we were close. I felt, that picture means we're close. Wilkins undoubtedly, and I think...

If you ask him, he will say that he feels that he did. If there were any cats to be let out of any bags, he'd done it. Well, that's perfectly true, but I think this science isn't supposed to be kept in bags, no more than cats. I mean, I don't know what he means, but I don't like it as a scientist, sort of working away and sort of saying, oh, no, tell the other scientists or something. I think it's the way to be working.

Science ought to be an open activity, so you can work as a community. It would have been impossible not to have bottles after seeing that picture. Spring came early to Cambridge in 1953. Watson and Crick were given official permission to return to their work on DNA. And by now they had managed to acquire all the information they needed. Chargaff's data suggested that the four chemicals in DNA might go together in pairs.

It was time to see how these pairs would fit together, to discover whether the shape of DNA would tell them what it did. The Cavendish shop was to build us some tin models, and that took too long. And, you know, finally in desperation, I made some other cardboard.

I sort of finished the job on Friday and didn't get back into the Cavendish probably until much before 9.30 on Saturday morning. So I came in the morning and I began moving them around. And I wanted an arrangement, you know, where I had a big and a small.

So, how did you do it? Somehow you had to form link bonds. So here's A and here's T. And I wanted this hydrogen. I point directly at this nitrogen, so I had something like this.

Oh! So then I went to the pair, and I wanted this nitrogen to point to this one. I went like this.

Whoa! They look the same. So we had two base pairs identical in shape. And, boy, I could hardly believe it. Franklin's photo suggested these pairs had to fit into some kind of helix.

And when they saw that the pairs were the same shape, they realized that they could stack on top of each other. You can put one right on top of the other. And they realized that to form a helix, they not only stacked on top of each other, but they also twisted around, like the steps in a spiral staircase, onwards and upwards.

In their minds, the double helix structure of DNA emerged. So you can have a small one, a big one, a small one, any sequence. We knew we could just, you know, even if we go up to the ceiling, we were building a tiny fraction of a molecule. 100 million of these base tests in one molecule. So unbelievably all united by this either AT or TA, GC, CG, all fitting into this wonderful symmetry which we saw the morning of February 28, 1953. The double helix was a structure that revealed far more about the way life works than they could ever have dreamed of.

They'd been looking for something that could divide, just like cells do, and it was easy to see how a double helix could unwind and form two more double helixes. They'd been trying to find out if DNA was the script or instructions for all living things. They realized that the millions of G's, A's, T's, and C's must be written in some kind of code, the script of life.

And they even saw how the script could be copied exactly as the As the double helix unwinds, each of the letters forms a new pair. And because A always goes with T and G always goes with C, the resulting two pieces of DNA are exact copies of the original, enabling the script to be passed from cell to cell and ultimately from generation to generation. It was clear now, DNA was the molecule that controlled all living things.

Watson and Crick ran straight to the pub, where their news was going to be hard to believe. It was hard to contain the fact that, you know, maybe we had a gigantic breakthrough. We'd done something really important. We had discovered the secret of life. You could say that day was the beginning of the new genetics.

They had the idea, but now they wanted to check that it was right. They set about building a tin model as quickly as they could, cross-checking their coordinates with the King's data. It all fit. Then we had to tell the people at King's, and... We were a bit apprehensive because we didn't want to say, well, we've beaten you.

You have to remember that I'd been up before and seen the model that was wrong. And that gave us a buzz and a high. And then you go up there and you see this thing.

It looked right when you saw it. It was so brilliantly, elegantly simple. I thought, oh, my God, we got scooped. Because I really thought we were going to come up with something like that ourselves.

It was terrible, you know, for Morris. I said that the double helix was somewhat similar to... a young baby standing there all alive and saying, I don't care what you say or what you think. I know I am right.

Rosalind would have been appalled to learn that they had taken quite so much detail of her current work and put it into their model. Arguing whether we behave right or wrong or we're good or bad guys depends on your set of values and the facts you have. The extent to which Rosalind Franklin was badly treated is still debated to this day. She's an enigmatic character who kept her distance from the other people in this story.

She spent her time working alone in her lab. People have wondered how close she came to finding the structure of DNA. The only way to know is to visit this archive in Cambridge, where her notebooks are kept. Her notes suggest that she nearly got there. In one of her final entries, she's thinking in terms of a two-chain or double helix.

But that's as far as she got. She died five years later in 1958, without ever being told the extent to which Watson and Crick had used her data. And when the Nobel Prizes were awarded for the discovery, they went to Watson and Crick and Morris Wilkins.

She didn't get one because Nobel Prizes can't be awarded posthumously. People who knew her say that... what she cared about most was that her work moved science forward.

It was one of the few things she had in common with Morris Wilkins. Without their work, Watson and Crick could not have built this model. And the model was just the beginning. Over the next two days, she was able to build a model For decades, scientists delved into the molecular world of DNA and discovered how it actually controls life. The genius who did more than anyone to unravel its mysteries was Francis Crick.

Today, he's at the Salk Institute in California. In one interview that has never before been broadcast, Crick did talk about what for him came after the double helix. It involves thinking beyond what he calls the narrow limits of normal human experience.

Now, when you want to understand the world, you have to go beyond those narrow limits, both up and down, both in space and time. And then you find that there's a uniformity and extraordinary things happening which you'd no idea of just looking at the world. And this is the fascination of science really, I think, to uncover so much which is not apparent just in everyday life.

Today we have a way to see the molecular world. This is what DNA looks like when you put the very latest scientific data into a computer simulator. It's a long way from Tinker Toy models. What is apparent is that everything in the molecular world is more strange and sophisticated than anyone had thought.

Biological systems are the result of evolution, and they produce very complicated things. Now, the reason that DNA looks so beautiful and simple is it goes right back to near the origins of life, where things had to be simple. But if you actually look at the actual process of DNA replication, it isn't at all the way that we used to describe it.

All sorts of funny things happen. You have to have proteins which will unwind the helix and nick it and then join it together again. You get an enormously, very complicated apparatus, which one might say molecular gadgetry, which actually does the job.

This is the incredible way DNA copies itself. But DNA is much more than a self-replicating molecule. It is the essence of life, carrying from generation to generation the information needed to make all living things, written in the DNA language of A's, C's, G's, and T's. Francis Crick wanted to crack this genetic code to understand the complete process of life.

To achieve this would involve deconstructing the gadgets of the molecular world. He started by working backwards. What's sometimes called reverse engineering. It happens in the commercial world when one firm produces a gadget and another firm buys it and tries to take it to pieces and find how it works.

That's called reverse engineering. But in our case, it's reverse engineering in what you might call a foreign culture. As a result of that process, today it's possible to see how DNA makes living things.

How DNA's code is turned into flesh and blood. And for scientists, life is no longer a mystery. The blue molecule racing down the DNA unzips the double helix and copies one of the two strands.

This copy is then released for the next stage of the process. process. The yellow copy feeds into another machine which deciphers the code and orders up the right components one unit at a time from the surrounding chemical soup.

The product of this machine is protein. This could be a thousandth of an eyebrow. The same process could make a tiger's claw or part of the wings of a dove. It's the same for all life. What is made is all down to the DNA, the specific order of the chemical code.

And today, these machines can read that DNA code. How a person is made is being revealed. How our brains are built is being explained.

In the G's, A's, T's and C's, they're beginning to read differences in our characters and personality. The genetics of human nature is slowly unfolding. Even our story can be seen in this way.

The fate of our characters determined by their... individual natures. I thought the problem would last me my lifetime.

I had no idea it would be solved within 20 years. You see, I was, I mean it was embarrassing almost to got to the stage where instead of this problem lasting for one's life, one had to look around for another problem. Now Francis Crick is trying to find out how the brain works.

He's always only been interested in making new discoveries. Jim Watson runs Cold Spring Harbor Laboratories on Long Island in New York. He employs 800 people and is still at the cutting edge of DNA science. He had a house built on the grounds and erected an enormous sculpture of the double helix.

He travels the world giving lectures and arguing for the benefits of genetic engineering. Our people say, well, we're playing God. You know, I have a straightforward answer. If we don't play God, who will? And Morris Wilkins couldn't be more different.

Having worked on the atomic bomb, he chose to study DNA because he thought it wouldn't be controversial. Today, as the newspapers talk of creating designer babies and the birth of human clones, he lectures at King's College London about the social responsibility of science. He hopes the human race will use this knowledge wisely.

Transcript for:The Discovery and Impact of DNA

Transcript for:
The Discovery and Impact of DNA