BOOK REVIEW / A gene's-eye view of the whole of creation: How the leopard changed its spots: The Evolution of Complexity by Brian Goodwin, Weidenfeld pounds 18.99

Click to follow
The Independent Culture
LIKE all animals, each one of us began as a single spherical cell, a minuscule fertilised egg that developed into an embryo and then an adult. The idea is completely familiar, yet the mysteries of development are still largely unexplained. How does one cell give rise to millions of cells, with differing functions, and in exactly the right proportions? How do these various types of cell become organised into elaborate complete structures such as limbs, eyes, kidneys, hearts and brains? How do these patterns remain stable down the generations? And where and how is all the necessary information stored or encoded in that egg?

These are some of the most fundamental and important questions in modern biology, ones which Brian Goodwin tackles head-on in this intelligent and fascinating - if unorthodox and often infuriating - new book. Most biologists working on these problems consider organisms to be essentially survival machines acting at the behest of their genes, whose goal is to leave more copies of themselves, a view brilliantly popularised by Richard Dawkins. Genes dictate which proteins are made in the cell, whereas proteins determine which chemical reactions take place and which structures will be present. This is the way genes control behaviour. The challenge, then, is to understand the relationships between the genes and the body's structure and properties: simply put, if we knew in detail all the genetic information contained in an egg, could we ever compute just how the embryo would develop?

Professor Goodwin says no. Although the genetic programme may tell us where and when in the developing embryo particular proteins and other molecules are made, this knowledge, he argues, is insufficient to predict what the adult body will turn out like. Basic chemistry illustrates why.

Carbon atoms can be linked or stacked together to produce diamond, graphite, or the football-shaped molecule baroquely termed 'buckminsterfullerene': one substance, several forms. The final form cannot be determined from the composition - we also need to know the conditions under which it was made. Similarly, Goodwin contends, 'organisms cannot be reduced to the properties of their genes, and have to be understood as dynamical systems which have distinctive properties that characterise the living state'.

So what kind of physical processes can give rise to life's bewildering complexity? Goodwin goes on to discuss the similarities between the complex spatial patterns of activity that crop up in heart cells, neurons, ant colonies and much more. The key to the idea is that intricate and unpredictable structures or behaviour can arise from following a few simple rules: that is, the properties of a system can be more than the sum of its parts - the developing embryo is more than the aggregate of its cells. Goodwin cites a wealth of mathematical and computer models to demonstrate several ways in which order may emerge in plants and animals from an ocean of possibilities. According to him, biological science - the leopard in his title - is changing its spots, moving 'beyond reductionism' to the study of 'dynamic wholes'. This is what he calls a 'science of qualities' (as opposed to quantities) that focuses on 'the unique qualities of organisms that give us a sense of their distinctive value and what it means to seek quality in life'.

Most of this impressive new science of complexity remains theoretical and is done on computers at the hip and sunny Santa Fe Institute in New Mexico. We are still awaiting hard experimental evidence from mundane living creatures. More seriously, Goodwin seems so obsessed with grand unifying concepts that he neglects to consider what the parts of the whole actually look like. For him, 'reductionism' is a dirty word, but for most scientists this method of answering big questions by studying small problems has enormous benefits: it is simple, it can be tested and it works.

In particular, his superfluous attacks on natural selection and 'gene-centred biology' fail to convince: complexity theory is, in fact, entirely compatible with Darwinian principles and molecular genetics, and genes almost certainly have more than a backseat role in development. By blinkering the gene's-eye view, Goodwin sadly glosses over the remarkable progress that has recently been made in our understanding of how cells work and communicate with each other, and how genes control these activities.

We have a lot more to learn about the developmental programme, but grubby experimental biology is already beginning to reveal some of its main themes - which is more than can be said for most of the theorists working at the 'edge of chaos'.

(Photograph omitted)

Comments