Review by Kevin Orrman-Rossiter

Life on the Edge: The coming of age of quantum biology
by Johnjoe McFadden and Jim Al-Khalili

“What is life?” is quintessentially the most thought-provoking question ever asked by humankind. Often confused with “What is the meaning to life?” the answers, from the mystical to the mundane, have never proved to be compelling. The suggestion that quantum mechanics may lie at the defining edge between ‘live’ and ‘not-alive’ may at first seem to be akin to the world-view the 19th century vitalists than 21st century modern scientists. That however, in Life on the Edge, is what McFadden and Al-Khahili are proposing; “at least one of the missing pieces in the puzzle of life is found within the world of quantum mechanics.”

In Life on the Edge, McFadden and Al-Khalili, introduce two of the fascinating quantum physics phenomena, quantum tunnelling and quantum superposition, via a number of seemingly commonplace biological topics: the homing precision of a migrating Robin, enzyme reactions at ‘normal’ temperatures, photosynthesis, and the anatomy of smelling. Many people would be familiar with quantum phenomena because they lie at the heart nuclear fusion in the sun and technologies such as electron microscopes and MRI scanners. The weirdness of particles in quantum systems to be a superposition of states until an observation is made has passed into common culture thanks to Einstein’s “Schrödinger’s cat” thought experiment. The act of observing the cat, is it alive or dead? forces the quantum states to become only one. This ‘decoherence’ of states is what separates the quantum world from the classical physics of our everyday world.

So shouldn’t we expect quantum mechanics to be at the heart of biology, which is after all a form of applied chemistry, which is a kind of applied physics? However this connection is usually taken only in its trivial sense. The macro world of biology, and everyday other occurrences, is shielded from the weird quantum stuff via thermodynamics – the randomising effects of scattering, vibrations and motions – and means we can get by without quantum mechanics most of the time…but not always.

The not always becomes apparent in the new science of quantum biology. Many animals employ the Earth’s magnetic field to navigate by. It has been proposed that magnetite, found in the tissues of some migrating species such as bees and some birds, may provide the ability to sense weak magnetic fields. However in 2004 the first experimental evidence was provided in support of the idea birds use quantum entanglement to navigate around the globe. An eye pigment, cryptochrome, acts as a chemical compass depending on free radical pairs being in a superposition of singlet and triplet states. This quantum entanglement is familiar to physicists from esoteric experiments involving particles in isolated systems, not the messy turbulent world of biology. This ‘decoherence’ of quantum reactions comes about because of the ‘noise’ of large thermodynamic systems. Nonetheless the evidence is compelling, even if the mechanisms are not fully understood, some properties of living systems depend on quantum mechanical phenomena such as tunnelling, coherence and entanglement.

As Erwin Schrödinger pointed out more than sixty years ago life is different from the inorganic world because it is structured and orderly even at the molecular level. What these studies are showing, and that McFadden and Al-Khalili bring to life in an engaging and accessible manner, is that living systems seem to be able to maintain quantum coherence in the warm, wet environment of living cells. These squishy, flexible structures would be expected to shatter the delicate arrangement that particles need to maintain their quantum behaviour.

In addition to this homing ability of birds, other systems, photosynthesis and enzyme reactions, are given a compelling discussion in Life on the edge. The evidence of these diverse findings strongly suggests that biological systems employ quantum phenomena at the heart of their macro behaviour. This has huge implications for the study of large-scale quantum systems and their possible technological innovations. More importantly, in my mind and that of the present authors, it poses interesting questions for our understanding of life. McFadden and Al-Khalili conclude that a description of living systems must include this remarkable ability, where living systems retain a connection with the deeper quantum realm by harnessing thermodynamics – life literally exists on the edge of a thermodynamic storm.

Life on the Edge is aimed at a lay audience, and in this it succeeds admirably. As the first book in a cross-disciplinary area of science it manages to explain in sufficient depth and sufficient clarity all the science that is needed to paint a clear picture for the reader. The book, as expected from Al-Khalili, is accurate and suitably referenced, sufficient to encourage further reading and back up the scientific claims. Jim Al-Khalili is theoretical physicist at the University of Surrey and in addition an author of a number of popular science books, including a personal favourite Pathfinders: The golden age of Arabic science. Jonjoe McFadden is also a professor at the University of Surrey, specialising in molecular genetics and is the author and editor of leading textbooks on molecular and systems biology.

A complement to Life on the Edge is Erwin Schrödinger’s What is Life? written in 1943, based on a series of public lectures given at Trinity College Dublin and spoken of with almost reverence by McFadden and Al-Khalili. Both James Watson and Francis Crick, co-discoverers of the structure of DNA, respectively acknowledged What is Life? as a source of inspiration for their initial researches. If you are then curious about the scientific search for the origin of life, the search for the how life can spring from non-life, A brief history of creation by Bill Messler and H. James Cleaves II, although for a more lay audience than Life on the Edge, is also recommended.

Life on the Edge is a well-written introduction to one of the most fascinating areas of modern science – quantum biology. For readers intrigued by the quintessential question “What is life?” – then Life on the Edge will enthral you.

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Kevin Orrman-Rossiter

Kevin Orrman-Rossiter is a freelance science writer and reviewer. His writing has features in COSMOS magazine, Books&Publishing, and online on Australian Science lucid thoughts and dragon laughing . Originally studying physics, Kevin had a successful research career, reaching the heady heights of an ARC Queen Elizabeth II Fellow, then after being lured into the fascinating world of industry research, he ended up some years later, in marketing and strategy. When not writing, reviewing, or reading books to review, Kevin is now found; forming links between Australian industry and researchers at the University of Melbourne, reading (what a lovely quaint term) History & Philosophy of Science at University of Melbourne, and, in defiance of ageing gracefully, trail running .