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In 1953 James Watson and Francis Crick, with the help of Rosalind Franklin and Maurice Wilkins, described the structure of the molecule at the heart of life. Deoxyribonucleic acid, better known as DNA, was, they said, a double helix, two spirals joined across the middle by pairs of four chemical bases, like a twisted ladder. That work earned Messrs Crick, Watson and Wilkins a Nobel prize and a place in the history books. The image of the double helix now often stands for biology, or even science, itself.

But this was merely the most visible breakthrough in a long struggle to understand the engine of life—how traits are inherited, mutated and weeded out by natural selection, and how the whole mysterious process works at the biochemical level. It is that lesser-known history that Matthew Cobb, a professor of animal behaviour at the University of Manchester, aims to sketch in his book, which has been shortlisted for the Royal Society’s Winton prize for science writing.

The result is a fascinating reminder of just how hard-won are the seemingly obvious facts of modern biology. The development of genetics was a tale of confusion, accident, frustration and the occasional flash of insight. It was, says Dr Cobb, as important as the Manhattan or Apollo projects, but with no government support and little money, carried out by scientists interested in the question for its own sake.

The researchers started from almost total ignorance. William Harvey, better known for describing the circulation of the blood, wondered in the 17th century what could explain why children’s skin colour was often a blend of their parents’, whereas they share a sex with only one, and can have an eye colour different from either.

In the late 19th century a monk, Gregor Mendel, established, through experiments on pea plants, the basic rules of inherited traits. A Danish biologist, Wilhelm Johannsen, coined the term “gene” in 1909 to describe whatever it was that Mendel had found. But as late as 1933 scientists were still debating whether genes were physical things or just useful abstractions, and how they could transmit traits. Scientists knew that DNA existed, but many considered it a boring bit of scaffolding in the cell. Proteins, which come in zillions of different varieties, were seen by many as the only things exciting enough to account for all the diversity seen in life.

After the second world war, ideas from information theory, arising out of wartime work on computers and automation, percolated into biology. Once the structure of DNA had been established, those ideas helped crack the problem of how the four chemical bases do their job. Proteins are built by stringing together 20 different sorts of amino acid. Strings of three bases within a DNA molecule represent these amino acids, but with 64 such triplets, there is much redundancy which information theory alone could not fully explain. Years of painstaking lab-work were needed to reconcile theory with reality.

Dr Cobb is good on the human side of the story, showing science as fuelled by rivalry, jealousy, competitiveness and wonder. The only downside is that he must marshal hundreds of scientists across several disciplines into around 300 pages of narrative. The results can sometimes be dense, and readers without a command of biological jargon will frequently find themselves consulting the glossary for guidance. But the cracking of the code of life is a great story, of which this is an accomplished telling.