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March 29, 2013 6:14 pm
Creation: The Origin of Life / The Future of Life, by Adam Rutherford, Viking £18.99, 272 pages
The best books about biological evolution have probably already appeared. Authors from Charles Darwin to Richard Dawkins have written masterly accounts of “descent with modification” through natural selection.
So Adam Rutherford, an up-and-coming British science writer and broadcaster, opted instead to write the “prequel and sequel” to evolution on Earth over the past 4bn years: how life began, and how humans are beginning to supplement or override nature by engineering synthetic life forms.
Rutherford’s chosen device is a “flip book” of two halves. He invites the reader to begin with either the origin or the future of life and then to turn the volume over. I imagine that almost everyone will begin like me with the origins – making the flip seem a bit gimmicky. If the author had written a conventional two-part book, with the future following on from the origins, he would have avoided the duplicative explanations, for example of how DNA works, that are inevitable in his format.
Even so, I warmly recommend Creation. Rutherford’s academic background in genetics gives him a firm grasp of the intricacies of biochemistry – and he translates these superbly into clear English.
Placing the origin of life firmly on Earth, he rejects “panspermia”, the idea that microbes or even biological precursor molecules such as DNA might have seeded Earth from space. Although simple organic chemicals are known to form in space, there is no evidence that more complex biological molecules could withstand interstellar travel. The precise chemical pathway that first created replicating, evolving molecules and led to simple living cells remains unknown. But recent experiments, combined with computer modelling, are showing how this process could have occurred in the hot, wet conditions of the young Earth.
The first self-replicating molecules were probably combinations of nucleic acids, the chemical units of genetic information in all life today. Initially these would have combined into short random sequences of RNA – perhaps within interstices of porous rock – and then converted into a primitive genetic code by selection pressures. Later the evolving RNA molecules would have associated with amino acids, the components of proteins, in microscopic bubbles that led to the first cells. “We now see emergent properties that are not improbable at all and are a lot less mysterious than we once thought,” Rutherford writes boldly. “The conditions of the infant Earth, tested in modern labs, render self-creation unavoidable.”
He insists that all life today must descend from one single entity, the Last Universal Common Ancestor or Luca. The evidence for this is that all organisms share not only the same genetic code but the same detailed biochemistry, and the chances of this having arisen independently more than once are minuscule. (It is possible that other evolutionary processes started several times on Earth but died out aeons ago.)
The common origin of all biology on Earth allows scientists to move genes between bacteria, plants and people – the starting point for Rutherford’s exploration of the man-made future of life. So far the commercial application of genetic engineering, for example to produce human proteins from microbial cell cultures or to make insect-resistant GM crops, has involved the transfer of a few genes at a time. The new field of synthetic biology is based on much more extensive re-engineering of living cells.
Its best-known practitioner, Craig Venter, has used lab chemicals to recreate the genome of an existing bacterium from scratch (with tiny alterations). He is now trying to make a microbe that does not exist in nature, as a living chassis for doing useful things like producing biofuels.
While Venter reinterprets the existing vocabulary of life, other scientists are trying to go further – changing the genetic code by inserting unnatural nucleic acids and making proteins from amino acids that do not exist in nature.
While recognising that some readers will be alarmed by this prospect, Rutherford adopts a gung-ho attitude. Essentially he argues that new life forms generated by synthetic biology are designed not to thrive in the wild and will not be robust enough to compete with organisms produced by 4bn years of natural evolution. We – or our descendants – shall see.
Clive Cookson is the FT’s science editor
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