It is now possible to allow artificial evolution to manipulate directly a real physical semiconductor medium to construct automatically electronic circuits that satisfy an engineering specification. Once preconceptions from conventional design methods are rigorously rejected, the silicon electronic medium can be exploited in a way that is truly natural to its properties, resulting in highly efficient circuits. Freely exploiting the physical properties of a medium has its pitfalls, and one is that the evolved circuit may be unable to operate over a sufficient range of temperatures to be of wide applicability. Natural evolution must have faced the same problem, and this paper aims to learn lessons from it. We shall see that there are strong correspondences between the natural and electronic cases at every stage of the discussion, with highly suggestive consequences.
The motivation behind this research is to improve evolutionary electronics as an engineering technique. However, there are broader implications for ALife researchers, and these will be identified in the penultimate section. There is a lot of biology in this paper, but I am not a biologist. The biological information is taken from [1] except where indicated otherwise by citations, but any errors are my own responsibility.
The next section summarises a recent experiment in evolutionary electronics to illustrate the motivation for this research. We then consider the fundamentals of how temperature influences biological and silicon systems. The subsequent sections consider first how a system may cope with temperature change (`Temperature Compensation') and then how a system's internal temperature can be stabilised (`Thermal Regulation'). Both are effective methods of sustaining operationality in the face of changing external temperature, and they can be used together. Finally, some implications for ALife modelling are noted.