Beautifully written and always engrossing...often recalls Foucault at his most lurid and gothic.

Daily Telegraph, London

Everyone's got quirks

Armand Marie Leroi presents this elegant and queasy account of mutants as a kind of detour, claiming to be less interested in the twisted, the hairy or the conjoined than in the average human. The errors are relegated to third place, as though an afterthought.

Can we believe Leroi? His book dwells so long on the pickled bodies of two-snouted pigs and human cyclops that one is reminded of the historian and philosopher Michel Foucault, whose vaunted interest in reason and justice led to books stuffed with graphic descriptions of insane asylums and bodies hung, drawn and quartered.

It is seldom one discovers a work as finely written as Mutants, yet so capable of causing distress. The descriptions of the processes that cause deformities are so vivid that I defy anyone to read it without imagining each individual cell prickling inside one's body. And the life stories of Leroi's mutants are just as hard on the sensitive mind, frequently ending in the freak show. Which is what happened to the hairy-faced family of Shwe-Maong who, in three generations, moved from the jungles of Laos to the court of King Bagydaw of Burma to the Egyptian Hall in Piccadilly and the stage of the Folies Bergère.

Mutants often recalls Foucault at his most lurid and gothic. Yet, while the two writers share a theatricality, Foucault was concerned with dramatising a decisive change in human affairs. Modern treatment of the crazed or the criminal, he argued, does not reflect universal human truths but, rather, is contingent on a new vision of ourselves as caring and rational creatures: a premise Foucault regarded as shaky. In contrast, Leroi is a scientist and Mutants is not a history but a positivist account of the way foetuses develop in the womb, with separate chapters on skin, on bones, on limbs, on gender, and so on.

In the chapter on embryos, we learn that the first two weeks after conception are not aimed at baby-building but at erecting the scaffolding for the future embryo: the placenta, the umbilical cord and, crucially, the keystone upon which everything will rest, a small disc with a groove along it known as the "primitive streak" (so evocative a term and yet, somehow, so punk rock).

As Leroi details the way that cells coalesce and organise along the primitive streak, the reason for his detour through mutation becomes apparent. By studying the way this process has failed, geneticists learnt to speculate on why it so often works out right. For instance, most of us carry our hearts on the left of our bodies, but one in 8,500 of us are reversed, with hearts on the right. Post-mortems of conjoined twins reveal that about half also exhibit this reversal, but in only one of the twins. Anything with a 50-50 chance looks suspiciously arbitrary, and so it proves.

The reason - and here we must get technical - is that little wiggly things laid down along the primitive streak will indicate which way round we should be orientated by waving. If these wigglers malfunction then it becomes a toss-up as to whether we beat on the right or left. The geneticists conjecture that in conjoined twins, the dominant wigglers overwhelm those of the weaker sibling. Among un-twinned right-handers, it is likely that the wigglers simply do not work, a conclusion supported by the fact that the wigglers are similar to the tails of sperm and to the structures that waft in our nasal passages ­ and right-hand-hearted men tend to be infertile with a poor sense of smell.

Leroi is a scientist, but he resembles Foucault in so far as his work intrudes upon philosophy. His broader thesis is that the genetic processes in the womb are so complex - contingent on so many variables in which infinitesimally small bits and bobs can play multiple roles, abandoning some functions and assuming others - that we are all mutants. This fact was brought home to me on a visit to the hair salon when the stylist pointed out the patch of colourless hair at the back of my head. I have had this patch all my life but, thanks to Leroi, I now recognise it as a mutation, as there is no world in which it could be an advantage or play a role in natural or sexual selection.

Leroi calculates that we all carry upwards of 200 mutations in our genes. By focusing on the most visible of mutations, and on the people we describe as mutants, he can ask about the meaning of human appearance. These thoughts come in an epilogue, but they are of such interest that one hopes the author swiftly follows this book with another.

Leroi broaches two questions: race and beauty. Geneticists have largely abandoned the question of race because there is no deep meaning to it, just surface similarities with quirky contingent roots. If race is a matter of appearance, rather than blood in the sense used by older theories, it may be trivial - but it is the kind of triviality that fascinates us. It is, surely, a sign of a cosmopolitan nature, rather than backwoods racism, to be able to detect the small similarities that distinguish people from the same part of the world.

In contrast, beauty is a matter of difference. Beyond the commonplace that an appearance of youth and health are desirable traits in sexual selection, how can we talk of startling beauty when, as Leroi's admirable book shows, there is no ideal geometry to the human physiognomy. Heart-stopping beauty is as freakish as any other mutation, but it touches upon a transcendental question: the creation of value where no value exists, exalted for its own sake.

In a world where Foucault's pessimism so often seems justified, any talk of transcendental value seems like a good thing. One hopes that Leroi receives the attention he deserves for Mutants, a beautifully written and always engrossing book. And one hopes the encouragement speeds him towards the next work, on beauties.

Nicholas Blincoe
Daily Telegraph, London (May 22 2004)