author : Brian C. Goodwin

Goodwin wants to put the organism back into biology, ousting, or at least complementing, the role of the genes.

Ever since Darwin the story has been growing that we, and all creatures, are a product of our genes, and that evolution acting on those genes steers creatures in the direction of greater fitness. But this description concentrates on the genes at the expense of the organism itself. It also seems to miss several points about organism structure. Goodwin provides varied examples of structure that seem to be caused mostly by the dynamic processes occurring as the organism develops, and only tweaked by any genetic component. For example the whorls that continually appear and then disappear on the stalk of Acetabularia in the early stages of its development have no very obvious adaptive explanation, but can be explained as a natural consequence of symmetry breaking and dynamical processes during the growth of the stalk.

Goodwin emphasises process over state. The dynamic process of an organism developing is more important, more interesting, than the state it develops into. And that process is more determined by the physical environment, the morphogenetic field it occurs in, than by the genes. These dynamical process, and their basins of attraction, constrain the forms the organism can take, and also only make sense in terms of the entire organism and its development.

Goodwin also shows how the metaphors we use affect the way we think about biological processes. As a very simple example, our talk of biological fitness peaks (rather than physical minimum energy valleys, say), leads naturally to a metaphor of an effortful struggling to climb those peaks (rather than a principle of least action, of effortlessly rolling down into the valleys). He also argues that the emphasis on genes and struggle arose so readily because it fit so naturally with then pre-existing cultural myths, especially of the Fall, sin and redemption. That has led to a "competitive" metaphor that may be harmful. The metaphors associated with complex dynamical systems may be less harmful "cooperative" emergent ones.

Towards the end of the book Goodwin leaves the biology of individual organisms, and looks at how the same principles of dynamical systems might apply to groups of individuals -- to societies. This is interesting, but rather underdeveloped, as it takes up only part of a single chapter. He concludes with a comment that this new biology of organisms leads to the idea that their value is intrinsic to their very existence, in contrast to a biology concentrating on genes, with only extrinsic value from what they do, and whether they succeed. He hopes that this will lead to a more sympathetic view of the rest of life on this planet.

Goodwin's biological arguments are certainly convincing. This is an excellent description of how important dynamical processes are to biological systems, and how biology is changing to a more theoretical, less "historical", science. He provides a T. Ingold quote that sums up what are the key features of this new science (not just biology, but all of complex systems theory):

Selected quotes

of the Beloussov-Zhabotinsky reaction:

This is a fascinating account of the laws of complexity, and how they are exhibited in various biological systems. We get accounts of physiology, of the brain, of social insects, of ecological webs, and of evolution. The book forms a good bridge between coffee table popularisations and detailed research papers. It includes technical details, but separated off into boxes, to make them easy to skip if so inclined. [The boxes are more difficult to read than they need be, though, using a font unsuitable for mathematics, in black on a dark grey background.]

We learn that genes aren't everything: that the interaction of the organism with its environment, self organising to the edge of chaos, provides a strong framework within which the genes can tinker.

We learn that dynamics is an important feature of these systems: brains are not simply passive recognisers, but active systems.

We learn of the importance of social insects.

We learn how the environment plays a large role in the observed complexity of social insects. Indeed, the differences in the environment alone may be sufficient to explain different behaviours in different specifies of ants.

There are some lovely examples of using 3D cellular automata to model nest building behaviour, again showing how it is the interaction with the environment can profoundly affect behaviour.

We learn that examining single species does not tell us enough about the dynamics of complex ecological systems. Multiple species interact in non-linear an non-intuitive ways.

We learn that adding a spatial dimension to the models has a dramatic effect on the solutions possible. New solutions become possible, by allowing waves of interactions to propagate through the space. This point is made by discussing solutions to non-spatial equations, where certain parasitic behaviours are non-viable, then adding a spatial component (usually only two dimensions) and diffusion or percolation, and showing that viable solutions are now possible. [Unfortunately, some later arguments are then given for the simpler non-spatial cases only, leaving me wondering if the results are meaningful.]

The book could do with better editing. It is somewhat stodgily written in places, there are typos, and in one chapter many of the reference numbers are off by one. Despite this, Signs of Life is well worth the effort of reading. It covers a great range of biological examples, showing how many kinds of complex behaviours, non-linear processes, and emergent properties occur. Although the maths is boxed off to protect the faint hearted, the actual equations discussed are very simple -- yet displaying that astounding complexity and subtlety of solution that pervades this whole subject. And the references to more detailed literature let you follow up specific cases of interest, should you want to.

Further selected quotes: