Unravelling the Double Helix The Lost Heroes of DNA

Most people will at least be mildly familiar with the story of how the structure of DNA was discovered. Francis Crick and James D. Watson are household names in this story as they went on to win a Nobel Prize. But can you name the third person to share it with them? Most people will also have heard of Rosalind Franklin, but as Gareth Williams shows, so many other people were relevant to this story. Watson and Crick only put the finishing cherry on the cake. Unravelling the Double Helix covers the preceding 85 years of breakthroughs, blind alleys, near-misses, and “beautifully executed bellyflops” by some of the greatest scientists of their time.

Williams takes 1868 as his starting point. We find Swiss doctor Friedrich Miescher washing pus-soaked bandages. He discovered a fluffy grey precipitate that could be isolated from cell nuclei that was definitely not a protein. He dubbed it nuclein, and though he had some awfully accurate hunches as to what it might be, he was never able in his lifetime to gather convincing evidence. A “lethal cocktail of indecision and perfectionism” prevented him from finishing much of anything.

From these humble beginnings, the reader is taken on a chronological journey of discovery. Williams has dug deep into books, archives, correspondence, academic articles, and society publications during the writing of Unravelling the Double Helix, adding over 70 pages of notes. A very helpful timeline and who’s who open the book, a feature I wish more history books like this would include. In 26 relatively short chapters, usually no more than 20 pages each, he combines lively biographical sketches of researchers with a neat and clear overview of how their research contributed to the bigger picture.

This includes, of course, Gregor Mendel, the monk whose name is immortalised in concepts such as Mendelian inheritance. His story has been told at length elsewhere. Far more noteworthy is the diverse cast of now largely forgotten scientists. Take Walther Flemming, who in the 1870s observed and drew the careful choreography of chromosomes during cell division. Or Thomas Hunt Morgan, who spearheaded the legendary Fly Room at Columbia University, New York, where he mapped mutations and provided the first insight that genes have a fixed location on chromosomes. Albrecht Kossel, who extracted and named the four nucleobases of DNA: guanine, adenine, thymine, and cytosine (plus uracil found in RNA). The father-and-son duo of William and Lawrence Bragg, pioneers of X-ray crystallography. Ray Gosling, who took the first X-ray photograph of DNA that was suggestive of its regular structure and worked with Rosalind Franklin. And many, many others besides.

Though Williams does a great job of bringing his subjects back to life, shining a light on both their careers and their personal lives, the real highlight of the book for me was the insight it offered into how science progresses. Sure, we all know the stereotype of science as a lot of groping in the dark. But Williams shows what this meant in practice with remarkable clarity. He warns the reader repeatedly how, with the benefit of hindsight, it is easy to be haughty and wonder why people did not figure things out sooner.

One conviction that held the field of genetics back for decades was that proteins rather than nucleic acids were the carriers of hereditary information. Zimmer briefly mentioned this in She Has Her Mother's Laugh, but Unravelling the Double Helix gives the full story. Four nucleic acids were simply thought not to be diverse enough to carry all the instructions to grow complex organisms, whereas the almost 20 amino acids then known could be combined in many more ways to build proteins, like letters in the alphabet.

I was fascinated to read how scientists reasoned their way through various faulty iterations of concepts. From the idea that each of the four bases combined into a tetranucleotide, with DNA consisting of many such linked units (like a stack of pennies), to the idea of a triple helix, or the discovery of base pairing – for the longest time people were slowly expanding their understanding of DNA’s structure without really knowing what it actually did. It was often relegated to a structural role, like scaffolding holding up the business end of genes: the proteins. Even as data started piling up suggesting otherwise, resistance to this idea remained fierce, notably by Alfred Mirsky who shuffled of this mortal coil in full denial of the importance of that other coil.

Some people came frustratingly close, but failed to see the potential of their ideas, unwittingly burying them in long papers in obscure journals. Others let themselves be cowed by the big and the famous. And there was plenty of back-room politics, fierce competition, and barely concealed backstabbing going on. Williams makes no attempt to airbrush people’s actions or characters to smooth out the rough edges, providing a captivating, true-to-life picture of the ongoing “rat race with some notable rats”. This is clearest in the final part of the book where the story focuses on the sprint towards the finish line by Crick, Watson, and others.

This story has been told extensively elsewhere and all three Nobel prize winners have shared their version of it in autobiographies (first Watson in his inflammatory The Double Helix, then Crick in What Mad Pursuit, and finally Maurice Wilkins in The Third Man of the Double Helix). Much, too, has been written about the unfair dismissal of Rosalind Franklin’s contribution. Williams, with the benefit of hindsight, gives a fair portrayal of events, while also highlighting where the different versions of the story contradict each other.

I admit that I have not read any of the above-mentioned biographies, so I might end up shooting myself in the foot by claiming Unravelling the Double Helix to be “the definitive story”. Let me just say that I would be very surprised if people claimed otherwise, as, to all appearances, Williams’s scholarship is incredibly thorough and his coverage fair and impartial. He shows people and their actions warts and all without picking favourites.

Outside of the “big names”, very few other scientists have received the attention they deserved, perhaps except for X-ray crystallography pioneer William Astbury (see The Man in the Monkeynut Coat). Providing that perspective on the long arc of history is Williams’s biggest and most valuable contribution. If you enjoyed other chunky books on the history of genetics such as She Has Her Mother’s Laugh, Genetics in the Madhouse, or The Gene: An Intimate History, this book is a must-read.