Joseph Jebelli reviews ‘Wetware: a computer in every living cell’, by Dennis Bray.
Sir Paul Nurse, Nobel prize-winning biologist and President of the Royal Society, gave a fascinating lecture at the Royal Institution earlier this year on one of biology’s ‘great ideas’ – the Cell. Taking over 200 years to fully develop, the idea of all life being composed of cells is still not fully appreciated. “This was a major milestone in biology; we don’t recognise nor celebrate it enough,” explained Sir Nurse. But Dennis Bray, Professor of computational biology at Cambridge University, does exactly that in his beautifully crafted book, ‘Wetware: a computer in every living cell’.
Drawing on analogies from simple computer games, such as Pacman, Bray begins by discussing the peculiar feeding behaviours of single-celled organisms. Whilst the scholarly tone of his writing soon becomes apparent, Bray does well to ease the reader into to a complex subject by describing cells at their most basic level of organisation. He argues that humans are usually reluctant to ascribe subjective states, such as hunger, pain, or fear, to single-celled organisms. But does, for instance, an Amoeba’s rudimentary anatomy really lead to functional simplicity? As we learn more about these microscopic creatures, it is clear that even at this level, cells are nevertheless complex, organised systems that must have a high degree of knowledge about themselves and their surroundings.
Bray quickly descends into the molecular realm of the cell, wherein he likens chemical diffusion and enzyme biochemistry to the conditional connections inside a computer. Proteins, he argues, represent the ‘wires’ between different processes of a cell, akin in many respects to the circuitry of the human brain. The digital nature of DNA, exemplified by its reduction to a two-digit binary code, is also employed to bolster Brays overarching idea that biological systems use ‘computational elements’ to carry out logical operations. His point is that the cell is not just a haphazard ragbag of chemistry; there is something deeper, more intuitive, and highly non-random about how cells operate that we still cannot explain.
Developing the analogy of nerve cell circuitry, Bray goes on to explain how molecules can function in a similar fashion to neural networks, and thus be modelled computationally to understand how systems of proteins convey information about their environment. Over billions of years of evolution these networks have been refined, trained, and modified by experience to give rise to the higher human faculties, including memory, self-awareness, and consciousness. The prose inevitably becomes more philosophical towards the end, drawing on the thoughts of other complexity scientists such as Stuart Kauffman, who suggests that Darwinism is not enough to explain the kinds of spontaneous order we see in the natural world.
This book has been criticised by some for being too vague, and for not delving deep enough into the regulatory systems and mechanics underlying cellular intelligence. But they have clearly missed the point entirely. If you want detail, seek out a cell biology or biochemistry textbook. As the author puts it, ‘Fortunately, I do not need to know every detail of every last molecule for my argument’. Indeed, wetware is about the bigger picture, and by broadly discussing different aspects of cell function, Bray brings some long overdue theory back into biology.
As Sir Nurse declared, “Until this date, biological explanations have tended to be in a common sense world, but the complexity I think we’re going to see in biology may move us into a stranger world.” Strange, subtle, and exquisitely sophisticated, life at the molecular level is fast becoming an impenetrable chaos of complexity. In Wetware, Bray steps back to take stock of what two hundred years of research, and a few billion years of evolution has done for life as we know it today.
Joseph Jebelli is a Neuroscience PhD Candidate at University College London (UCL) studying the cellular and molecular mechanisms of neurodegenerative disease.