DNA is a modern day marvel. In a short amount of time, a whole new branch of research has evolved, and grown into an enormous industry. The extent of knowledge at the present time would have been unthinkable (and - pun intended - "inconceivable") 40 years ago. The pace of research in this very fruitful field will probably make similar huge advances in the next same time frame.This book scratches at the surface of the field, and lifts the lid a little. For me, the real shame is that it does not give more detail. Anna Mayer's work was published in 2005, and since that time there has been a steady stream of criminal cases where DNA preserved for over 20 years has been analysed with modern techniques. Consequently, previous suspects have been shown to be either innocent or guilty.The tone that Mayer adopts is a little too chatty for my liking. However, the book as a whole works together well, and the linking between the discreet topic-based chapters words well. The scope, though, is limited, and can seem repetitive within that.  What is surprising is that DNA can exist outside of living organisms for surprising amounts of time. Here the timescale is not just for 10 minutes, 10 days or 10 weeks, but 10 years, or even 10,000 years.Mayer presents the cases that were trumpeted in the popular press at the time for DNA remaining present for far longer periods. This would make not only a true Frankenstein possible, but also the creation of a Jurassic Park, or Arthur Conan Doyle's The Lost World. In her analysis, she discusses the replication of a small DNA sample into many identical copies, and the terror of researchers, test contamination. If Jurassic park is a step too far, though, it may be possible to bring recently extinct species, by DNA extraction. Mayer rightly points out some of the moral dilemmas in doing this. I would have liked to see more analysis and concentration on other areas of (possible) moral conflict.One part that does work well is the historical perspective given to some genetic problems of identity. That aside, Mayer indicates that such cases can be solved in the same way that paternity suits are solved. Unfortunately, there is insufficient detail for me of how such cases are actually solved.I can understand the double helix in concept, but for me, a portion of the double helix is either present or not. Mayer does not adequately explain how a portion that is extracted (e.g. from a frozen Mammoth carcass) can be `broken' or incomplete. Therefore, it is hard to understand how finding only a bit of DNA is a problem. The book can seem both `thin', and quite repetitive. To sum up, Anna Mayer presents the idea of DNA existing for a long time, and that as such it could help with solving some problems. Does it solve them? Yes, No, Yes, No.Mayer lifts the veil on DNA, particularly on what she describes as ancient DNA, but tantalisingly, it is not lifted very far. It left me wanting more, which may well be a good thing. I have no intention of turning to a life of crime, but some of the insights into possible lines of investigation caused me to be AFRAID to commit even small crimes. Perhaps this is a good reason to recommend the book to some members of the global community. Whether they would read it is another matter. Peter Morgan, Bath, UK (morganp@supanet.com)

Hunting the Double Helix: How DNA Is Solving Puzzles of the Past PDF

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