Self-Organization in Biological Systems

This book deals with self-organization in biological systems and constitutes a much-needed supplement to the mainstream treatment of behavioural ecology by Krebs & Davies (1997). In combination with Termites, Turtles and Traffic Jams by Michel Resnick (1994), it is an excellent textbook for courses on self-organized biological and social systems. In an admirable way it combines detailed experiments with mathematical models of behavioural ecology. Models based on differential equations are supplemented by individual-based models in Starlogo which can be downloaded from Camazine’s web site. Examples mainly concern social insects (such as ants and bees), but there are also chapters devoted to bacterial aggregates and fish shoals. The first seven chapters describe and analyse selforganization. Examples of self-organized behaviour are set against the usual explanations, which involve a leader, a blueprint, a recipe and a template. The authors also indicate how self-organization of behaviour may be studied experimentally, mathematically and by the combination of the two methods (Chapter 6). They introduce various types of models. As regards the evolution of behaviour, they suggest that self-organization and natural selection act together and that it is through selforganization that evolution becomes truly efficient (Chapter 7). Chapters 8–20 illustrate the process of self-organization with examples of grouping, foraging, dominance hierarchies, behavioural synchronization, building of nests and thermoregulation of swarms. The authors emphasize the operation of positive and negative feedback in all these processes. Chapter 8 shows the importance of chemotaxis (following increased concentrations of a chemical) in the life cycle of the famous slime mould, which alternates between phases in which single amoebae are solitary and ‘collective’ phases in which a great number of amoebae form a single, slug-like body. They describe, for instance, how a positive feedback mechanism brings (hungry) amoebae together and how this is accompanied by waves of c-AMP which may be concentric or have a spiral form (a curious difference that unfortunately is not explained). Three of the following chapters (9, 13 and 14) continue with the effects of chemotaxis, which may lead to the clustering of beetle larvae (Chapter 9), to the efficient way in which ants forage (Chapter 13) and to the complex patterns of swarming of the huge colonies of army ants (Chapter 14). In all this both a positive and a negative feedback are involved. The positive one implies that a larger group of organisms attracts more members, because