What Is Life? By Paul Nurse

This “little” book—almost pocket size—and written by one of the greatest living biomedical scientists—deals with a fundamental question of many dimensions. Naturally, it takes a personal approach but has a healthy enjoyable amount of historical context. It is very easy to read and should appeal to a broad readership from teenage enthusiasts to professional biologists.

The subtitle is “Understanding Biology in Five Steps,” the first of which is the cell. It is said of the “atom of biology” that the outer membrane is a critically important part. This is indeed the case and, coming from the field of bioelectricity, I immediately looked for a mention of the membrane potential, a force of up to some 10,000,000 V/m, found in every cell in the body, even red blood cells without a nucleus. It was not there, but I was glad to see that the second law of thermodynamics does get a mention.

 David Fickling Books, Oxford, UK (2020).

The cell leads to the gene and Sir Paul continues in his unassuming style, often citing family connections, for example, in relation to genetics (he was recently reported to be using a commercial service to dig into his own ancestry). As is to be expected from a geneticist, DNA gets good coverage and alongside some well-known names, we hear about Raymond Gosling, a PhD student of Rosalind Franklin who also played a significant role in the crystallization of DNA. This could be a quiet yet powerful message to PhD students, whose lives are not always easy, that it is possible to make a positive impact and find a place in history even at an early stage of a scientific career.

We also learn that there are at least 500 genes involved in the cell cycle of fission yeast, the author's favorite model. It is fascinating to read how, starting one wet Edinburgh night, riding his bicycle up the hill to reach the laboratory, his curiosity led to the discovery of cdc2, one of the key cell cycle genes. This makes an intriguing tale of the science and the way Sir Paul advanced it, all the way to a Nobel Prize.

But this book is not all about the past. Sir Paul brings us up to date with our 22,000 genes and the need to understand how subtle differences in their sequences can lead to marked differences in our personalities and behavioral traits. This logically leads to “Evolution by Natural Selection,” the intensely creative process that has produced us, and the extraordinary diversity of other living creatures. He describes an initially frightening eye-to-eye encounter with a silverback gorilla in a Ugandan rainforest, which was followed by a sensation of affinity, attributed to the sharing 96% of the gorilla's genes. This remarkable “commonality” of genes also manifests itself years later, when Sir Paul's student discovers that a homologue of the cdc2 gene is expressed in humans and relates directly to the uncontrolled proliferation of cells that can give rise to cancer. This unexpected finding also illustrates the power of using model systems in biology.

“Life as Chemistry” is the fourth section, covering enzymes and cellular metabolism. Some of the author's early heroes are Antoine Lavoisier and Louis Pasteur. We now learn about the electrical charges of molecules and their involvement in the chemical reactions that drive the frantic metabolic activities of the cell (animal and plant)—so perhaps the author can be forgiven for neglecting to mention the membrane potential earlier! There is a particularly insightful account of the work of Peter Mitchell on the mechanism cells use to produce the energy-rich compound, adenosine triphosphate. Amazingly, Mitchell carried a lot of his work in his private laboratory. We also learn how Mitchell ignored his doubters and went on to prove that his unusual concept (at the time) of chemiosmotic pumping of protons in mitochondria was correct, leading to a Nobel Prize for Chemistry in 1978.

Sydney Brenner apparently said, “We are drowning in data but thirsty for knowledge.” How true, even today! This takes the book to the fifth chapter on “Life as Information.” We do not hear about bioinformatics or artificial intelligence, but about how DNA molecules encode the information that ultimately enables the synthesis of the 200,000 proteins that our lives depend on. Sir Paul also discussed “what is life” over a Parisian lunch with François Jacob, who, with Jacques Monod, studied how information flows from gene sequence to protein to cellular function. The author understood more of the meaning of life when he was diagnosed with a serious heart condition that was treated successfully by surgery. Of course, no account of information processing would be complete without a mention of Alan Turing—including his little-known theory of spatial information flow within developing embryos.

The book finishes with two concluding chapters. In “Changing the World,” Sir Paul deals with a diverse range of current topics including the UK National Health Service, COVID-19, antibiotic resistance, cancer, and even modern farming practices and their impact on life. He complements these by covering revolutionary molecular techniques such as CRISPR-Cas9 and synthetic biology.

Finally, he returns to the theme of “What is Life”, highlighting his guiding principles, almost as a physicist would do with certain elegance. His answer rests upon three prerequisites – ability to evolve, being separate from the environment (but connected to it), and having the machinery (including genes) to grow and to reproduce. Thus, Sir Paul elucidates one of the most fundamental questions of biology and defends a series of messages of survival value to mankind. To my delight, he cites my old friend the late Sir George Porter (another Nobel Prize winner), as saying, “To feed applied science by starving basic science is economizing on the foundations of a building so that it may be built higher. It is only a matter of time before the whole edifice crumbles.” This book is constructed on solid foundations and rests on the shoulders of giants.