In 1943 the great physicist Erwin Schrödinger, of both-dead-and-alive-cat fame, gave a series of lectures at Trinity College Dublin, published the next year as his book What Is Life? He supposed that genes must take the form of a “huge molecule” containing a “miniature code” to direct the subsequent development of the organism. Francis Crick and James Watson, inspired by Schrödinger’s work, later proved him right when they, along with Rosalind Franklin and Maurice Wilkins, discovered the structure of DNA. But Schrödinger’s central question remains unanswered. There is still no agreed-on definition of what life is, let alone how it started. Maybe, some suggest, there are biology-specific laws of nature that we have yet to identify. Indeed, Schrödinger himself argued that “living matter, while not eluding the ‘laws of physics’ as established up to date, is likely to involve ‘other laws of physics’ hitherto unknown”. One fashionable approach now in biology is to suppose that these laws have something to do with “information”. In the age of mechanical inventions, it was thought that animals were like marvellous clockwork machines, and the entire universe was a sort of fabulous Meccano construction designed by God. Now we are in the information age, it seems obvious to us that the human brain – even, in some theorists’ view, the cosmos as a whole – must be a computer, and that information itself somehow underlies reality. The conceptual problem here is that the idea of “information” makes sense only in the context of an observer for whom something out there, in the indiscriminate jumble of the world, counts as information. Before life exists, there cannot be any such thing as information. It is to the credit of the physicist Paul Davies, then, that in this brilliantly vivid little book he is careful to remind the reader that such uses of “information” should be bracketed with provisos, even as he shows what we can do with them. It seems irresistible to say, to begin with, that cells “signal” to one another chemically, or that flocking birds and shoaling fish are exchanging “information” with their neighbours about speed and direction. But things get a lot weirder when Davies applies to biology ideas from thermodynamics and the mathematical theory of information. James Clerk Maxwell, originator of Maxwell’s Demon. Photograph: Baldwin H Ward & Kathryn C Ward/Corbis The “demon” of the title is Maxwell’s Demon, named after a thought experiment by the 19th-century Scottish physicist James Clerk Maxwell. Imagine a box of gas with a partition containing a tiny door. A supernatural intelligence could open the door to let fast-moving particles go one way and slow-moving particles the other. This would eventually result in two different temperatures of gas either side of the partition, reversing entropy and enabling work to get done free. The big idea is that nature itself might take advantage of the superefficiency of a demonic approach to information, and understanding the information flow in organisms might be the missing part of our scientific jigsaw puzzle. Davies proceeds to explain the maths of cellular autonoma, the ridiculously fine-tuned machinery of the cell and the workings of the “hive mind” in social insects. The information flow in genetics, too, is far more complex than once thought, a point piquantly illustrated by some perverted worm-botherers. These researchers discovered that by cutting the head and tail off a worm and applying electricity – which disrupts the information flow in regrowth – you can get a worm with a head at both ends. If you then cut that worm in half, just for lolz, you get two new two-headed worms, even though they have exactly the same DNA as the original one-headed worm. The informational approach, in Davies’s elegant and lucid exposition, is extremely promising, but it remains highly speculative, as he himself laudably emphasises while offering his own final thoughts on consciousness (as “integrated information”), and the possibility that “laws of nature” themselves evolve through time. Perhaps, he adds, these laws might, in some way not yet understood, be inherently “bio-friendly”. This is a maverick idea, but not a new one. The philosopher Thomas Nagel was widely ridiculed by scientists a few years ago when, in his book Mind and Cosmos, he suggested that there might be “teleological” laws ensuring that consciousness would arise in the universe. Teleology – the ancient idea that things strive towards a purpose – is not now respectable, and Davies himself refers to it as a “problem” to be avoided. And yet right at the end of this book, he suggests that “the emergence of life, and perhaps mind, are etched into the underlying lawfulness of nature”. That idea is nothing if not teleological – which is no good reason, by itself, to think it untrue. • The Demon in the Machine: How Hidden Webs of Information Are Solving the Mystery of Life is published by Allen Lane. To order a copy for £17.60 (RRP £20) go to or call 0330 333 6846. Free UK p&p over £15, online orders only. Phone orders min p&p of £1.99.