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		2.6.1— The Advantages of Chaos

		We are often impressed by the exquisite detail and sophisticated function of biological systems. Thus we might think that the complex and unpredictable output of a chaotic system would be useless or even dangerous to living things. In fact, chaotic systems can provide important characteristics needed by biological systems.

		1— Variability

		The variability in the output generated by a chaotic system means that the variables of the system will span a wider range of values. This variability can be useful to biological systems.

		For example, in learning, chaotic processes in the brain could explore a wide range of new neural connections to encode the new information. In remembering, chaotic processes could search a wide range of memories to find the goal of the search. Chaotic processes in the heart could increase the variability of the heart rate to help it adjust to changing internal and external demands.

		A lack of variability may characterize an unhealthy state. For example, the rhythmic seizures in epilepsy or some of the rhythmic patterns of the beating of a diseased heart represent a lack of variability.

		2— Control

		Paradoxically, the most surprising advantage of chaos is that it allows both finer and faster control of systems.

		In linear systems, small changes in the input produce small changes in the output. To produce a big change in the output therefore requires a big change in the input.

		However, chaotic systems have sensitivity to initial conditions and bifurcations in behavior with small changes in parameters. A delicate adjustment of the input can make a dramatic change in the output.

		Thus chaotic systems can be controlled finer and faster, with less energy, than linear systems.

 

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