[A] fascinating and immensely readable book

Financial Times

Freak out: a genetic lottery can make any one of us a mutant or a model.

There is a building on the outskirts of Amsterdam that has rooms of terrible things — specimen jars contains the teratological collection of 19th century physician Willem Vrolik. They hold the preserved bodies of infants, mostly stillborn, with hideous deformities. One has a melon-like head; others had their backs cleaved open or their brains spilling out. A pair of conjoined twins floats in fluid, the smaller a "parasite" that protrudes from the roof the mouth of the larger.

Ancient writers invested such mutants with moral significance and spun myths about the living ones — the Cyclopes with a single eye, the Sciapodes with a single, enormous foot.

We have long abandoned superstitious notions about deformed births being ill omens for kings or besieged cities. We know that they derive from errors in proof reading, mistakes in the gene code, which in turn disrupt the unimaginably complex process of turning a single, fertilised cell into a baby. And today, severely deformed human beings appear to belong to a vanished era. Ultrasound scans, legalised abortion and greater sensitively about disability man that few of us see such things. This is the irony at the heart of Armand Leroi's fascinating and immensely readable book. A t the same time that they have become invisible to the public, mutants are thrust into prominence by molecular genetic research. As Leroi, a reader in evolutionary developmental biology at Imperial College London, lucidly demonstrates, mutants lie at one end of a spectrum that stretches from the hideously deformed to the breathtakingly beautiful.

At conception we each enter a genetic lottery, one in which virtually all the tickets carry penalties. Every embryo has about 100 mutations unique to itself of which about three will be harmful, albeit usually only mildly. This is on top of its mutational legacy. "The average newly conceived human," Leroi says, "bears 300 mutations that impair its health in some fashion." Some can be mild, such as having one rather than two canine teeth, while a few may be socially desirable — the "loss of function MCIR mutation gave the model for Dante Gabriel Rossetti's painting "La Ghirlandata" her glorious red hair. A the other end of the spectrum, foetuses with a single cyclopic eye, for instance, have a fatal alteration in a developmental gene which means their brains fail to divide into two hemispheres.

Much of the book is taken up with tracing the effects of these mutations. Leroi skilfully interweaves this with stories of extreme mutants such as Elizabeth Ovitz, who had "pseudo-achondroplastic dwarfism" and survived the sadistic attentions of Joseph Mengele in Auschwitz, or biological pioneers such as a researcher who spent years trying to fuse newt embryos surgically.

Genetic research is made possible by the fact that genes are remarkably conservative across the animal kingdom. The same genes that control the development of segments of a fruit fly's body also issue instructions for the building of a mouse spine. Research is therefore dependent on the creation of a mutant mouse mountain. For every one of a human's 30,000 or so genes, geneticists breed several hundred mice and rates with that gene knocked out to see what problems it causes. The number of knock-out rodents required is expected to exceed 60 million. Inevitably, most animal research is devoted to uncovering the changes underlying diseases and deformity. But the logic of Leroi's mutation spectrum is that the winners in the genetic lottery are every bit as biologically interesting as the losers. Why do we find some people beautiful and why does beauty have such power? Leroi suggests it is because it tells us something valuable about mutations. Perfectly proportioned faces and flawless cheekbones broadcast a vital piece of evolutional information — I am a winner in the mutant lottery.

Jerome Burne
Financial Times (15 May 2004)