Mutants

  • Armand Marie Leroi
Viking: 2003. 320 pp. $25.95

Nature and nurture have a capricious power to alter body form, often with monstrous outcomes. Only relatively recently has it become morally unacceptable to collect and exhibit human examples. At the same time, huge strides have been made in understanding the molecular events that pattern and define the form of living creatures. It is perhaps ironic that this understanding has often been based on the deliberate creation of equally deformed model organisms.

Armand Leroi has realized that our expanding knowledge of the molecular underpinnings of development means that we may now be able to revisit these unfortunate humans, no longer to gape and stare, but to see if we can apply our understanding to the only organism in which we are really interested — ourselves. The result of this realization is his new book, Mutants.

Leroi has an extraordinarily extensive familiarity with a dazzling range of information that stretches from Neolithic sculpture to molecular developmental biology in the pages of Nature in 2002, and he draws on this to detail the remarkable molecular catastrophes that have been visited upon some unfortunate humans. He seeks to relate these cases back to a modern explanation based on molecular developmental biology, and in so doing to illustrate the principles that lie behind our development.

The story unrolls in three critical chapters that cover the control of overall body form. Conjoined twins lead us through the establishment of the three basic tissue types and the power of the 'organizer' to direct their development. Next, the one-eyed Cyclops of Greek mythology and terrible images of its human counterparts lead us to the wonderful elegance and simplicity of the homeotic genes and their ability to specify the identity of body parts. A chapter on limb development and failures to control limb induction then rounds off this most fundamental level of control of body form.

So far, Mutants might sound like yet another textbook, but this could not be further from the truth. What textbook would start a section on limb development with the story of two religious dissenters, Margaret McLaughlin and Margaret Wilson, who were tied to a stake in the River Bladnoch in Scotland and left to be overwhelmed by the rising tide and the estuarine crabs? And what's it got to do with development? You may well wonder. Their executioner was supposedly 'punished' for his cruelty by his children being born with hands like crabs' claws. Leroi uses this story to tease out the controls of limb development through tales of crook-footed Hephaestus, the two-toed Wadoma tribe of Africa, the armless fiddler of Germany, the handless and footless aleijadinhos of Brazil, Le Petite Pepin with his thalidomide-like shortened limbs, and finally even Charles Darwin (for his views on polydactyly). Leroi uses this wild and exotic cast of characters as the basis for discussion.

The next four chapters gallop through the control of skeleton development (or lack of it, in the case of Harry Eastlake, who died at 40, his normal skeleton encased in another); the control of size (here we find pygmies, giants, monsters and castrato opera singers); gender (illustrated by the amazing observation that hyenas give birth through an enlarged clitoris, and by the tragic suicide of Abel Barbin, born as a girl to die as a man); and, finally, skin and hair, where we meet albinos, piebalds and the hairy Shwe-Mong and his children at home in the Burmese court.

At this point, with only the briefest pause for breath, Leroi charges into the penultimate chapter, on ageing. This is a departure from the more morphological focus of the work so far and, for me, is less exciting. Ageing has all the features of being an innate property of an organism's biological constraints, and I confess to being prejudiced — it is too hard for us right now and is better left alone.

The final chapter, though, is wonderful. We all choose, or are driven, to be excited not by all of science itself, but by some more limited domain; Leroi is driven by a fascination with the morphology of race and, more personally still, by the biology of beauty. I too know the effect of a mutation in the MC1R gene, which is responsible for redheads, and I know that it is beautiful. Leroi draws tight his net of wonderful human diversity and gracefully displays its contents, and I am full of admiration for his willingness to build on his declared prejudice.

Despite its subject matter, Mutants is an exquisitely life-enhancing book. It captures what we know of the development of what makes us human, and it recognizes the random tragedy inflicted by nature and nurture. Read the book and you will be exposed to both a scientific world that no longer exists and to that of the twenty-first century. Read it and you will know a tiny part of what it is that has made you the person you are. Read it and enjoy words written carefully, elegantly and with sensibility. Read it and marvel.