Misread in tooth and claw

At the foot of this book's dust-jacket is a disclaimer to the effect that this work is in no way connected with the books or films entitled Jurassic Park and The Lost World. So what is it all about? The films have their origins in the writings of Michael Crichton, whose plot revolves around the notion that it is possible to rebuild dinosaurs by isolating their DNA from dinosaur blood, which was sucked into the stomachs of biting insects at the time when they lived (between 200 and 65 million years ago). These insects have been preserved by getting stuck in the sap exuded from conifer trees (which hardened to form amber).

This neat sleight of hand formed the basis for an exciting novel and two hugely popular films. The hype created by them has been enormous, as those who work on dinosaurs have discovered, and the time spent trying to introduce a modicum of objectivity into discussions concerning the prospects of bringing dinosaurs back to life has been distressing. So it was with some reticence that I replied to the request to review this book, given its title. However, I was mistaken. This is an excellent book and one that aficionados of Jurassic Park as well as the slightly loopier members of the press should be forced to read.

One of the authors, Rob DeSalle, is an associate curator at the American Museum of Natural History in New York and has been involved in the isolation and identification of ancient DNA molecules from amber-entombed insects, and is thus supremely familiar with the techniques associated with such work. The other, David Lindley, has worked as an editor with two of the top international science journals Nature and Science and has written a couple of books on the popular understanding of physics. Neither of course is a dinosaur expert, but one can analyse the techniques espoused by Crichton and the other can put the information across clearly to a lay audience.

The book opens with an interesting piece of theatre. The viewers settle down to view Jurassic Park ... the VCR is on, the popcorn is to hand, off we go. But the story is punctuated by questions from one of those know-it-alls in the audience - you know, the one who comes up with those irritating little facts that get in the way of a good story: the setting for Dominican amber mines is wrong, the age of Dominican amber is wrong, etc. So little improvements are made to the plot and eventually our explorers discover some amber in less exotic New Jersey (of the right age, with an insect preserved inside) -the Isle of Wight might have done for the English audience - but no matter, the purpose of this little exercise was to get to the point where a beautifully preserved insect in amber has been discovered - the starting point from which the Jurassic Park story unfolds.

In succeeding chapters the authors tease the whole story apart in a delightfully thorough manner. An introductory section skates across some aspects of DNA research, which shows that a tiny fragment of DNA from a beetle that lived in dinosaur times has been identified already - thus showing that biological molecules can be preserved for more than 100 million years - if the conditions are right.

There is also a rapid gallop through some aspects of dinosaurian research and our current understanding of the group as a whole. A cautionary resume of this section points out that despite incredible advances in molecular biology and genetics there is still an awful lot that is not known about development: for example how chicken DNA performs the transformation from egg to adult chicken and the fact that a myriad of steps are involved in the production means that the opportunity for failure because of missing links in this chain is astonishingly high.

The remainder of the book then proceeds to run, step by step, through the processes by which a real scientist might go about obtaining DNA from an amber-embedded insect. The laboratory protocols are explained in a logical and user-friendly way, as are the techniques used for chemical extraction of potential DNA. As the narrative progresses, it becomes increasingly obvious that the problems surrounding the scenario of collecting dinosaur blood from blood-sucking insects entombed in amber are basically insurmountable and alternative scenarios have to be created. A lump of muscle tissue torn from a fighting dinosaur is imagined to have plopped into some sap/amber - and this has been discovered. Given as many favourable circumstances as possible, the authors can conceive of the possibility of obtaining a series of fragments of dinosaur DNA.

But yet again that is merely the beginning of the problem. Taking a few fragments of DNA back to an entire DNA molecule, and in turn back to the chromosomal make-up of the original dinosaur requires a template that does not exist, and can only be guessed at. Even if you obtained a whole genome, how could the genome be made to express itself without its normal host egg and the appropriate chemical signalling and regulation which were responsible for the correct expression of the genome to cause growth and development of the embryo? If all this could be overcome how would the animal be grown (could you synthesise something as "simple" as an egg of the correct dimensions to allow the embryo to grow correctly)? How would a hatchling be reared? How would it learn its behavioural repertoire? How could it cope with its immediate biological environment?

The questions, without answers are almost endless. DeSalle and Lindley go on to consider some of the chaos-theory notions generated by one of the characters in the plot, and use this to examine some of the ecological absurdities created by the film. Some of these ideas indicate that neither author was a dinosaur expert - but in truth the problems encountered by considering the Jurassic Park scenario as serious science are preposterously large, as any right-minded palaeobiologist, or developmental or molecular biologist would agree. DeSalle and Lindley tell you so, and tell you precisely why. They also pause near the end to consider briefly the ethics of this sort of experimentation, and the potential that is being unleashed by genetic and molecular biology for a subtle form of eugenics, which makes all the hype about "can we/should we bring dinosaurs back to life?" pale into insignificance.

This is a truly excellent book. It candidly dissects the scientific notions that lie behind Jurassic Park and does so in a way that anyone with an interest in the topic should be able to follow reasonably closely. It debunks the whole scenario very effectively and is a perfect antidote to all the ridiculous hype surrounding these films. Steven Spielberg is a fantastically successful film-maker; he has created some of the best fantasy movies ever; and that is all that Jurassic Park and The Lost World are - pure fantasy, no more, no less. If anyone says otherwise, give them a copy of this book for Christmas.

David Norman is director, Sedgwick Museum of Geology, University of Cambridge.